1 <?xml version="1.0" encoding="utf-8"?>
2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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5 <title>The Altus Metrum System</title>
6 <subtitle>An Owner's Manual for Altus Metrum Rocketry Electronics</subtitle>
9 <firstname>Bdale</firstname>
10 <surname>Garbee</surname>
13 <firstname>Keith</firstname>
14 <surname>Packard</surname>
17 <firstname>Bob</firstname>
18 <surname>Finch</surname>
21 <firstname>Anthony</firstname>
22 <surname>Towns</surname>
26 <holder>Bdale Garbee and Keith Packard</holder>
30 <imagedata fileref="../themes/background.png" width="6.0in"/>
35 This document is released under the terms of the
36 <ulink url="http://creativecommons.org/licenses/by-sa/3.0/">
37 Creative Commons ShareAlike 3.0
44 <revnumber>1.6.1</revnumber>
45 <date>15 July 2015</date>
47 Minor release adding TeleBT v3.0 support.
51 <revnumber>1.6</revnumber>
52 <date>8 January 2015</date>
54 Major release adding TeleDongle v3.0 support.
58 <revnumber>1.5</revnumber>
59 <date>6 September 2014</date>
61 Major release adding EasyMega support.
65 <revnumber>1.4.1</revnumber>
66 <date>20 June 2014</date>
68 Minor release fixing some installation bugs.
72 <revnumber>1.4</revnumber>
73 <date>15 June 2014</date>
75 Major release adding TeleGPS support.
79 <revnumber>1.3.2</revnumber>
80 <date>24 January 2014</date>
82 Bug fixes for TeleMega and AltosUI.
86 <revnumber>1.3.1</revnumber>
87 <date>21 January 2014</date>
89 Bug fixes for TeleMega and TeleMetrum v2.0 along with a few
90 small UI improvements.
94 <revnumber>1.3</revnumber>
95 <date>12 November 2013</date>
97 Updated for software version 1.3. Version 1.3 adds support
98 for TeleMega, TeleMetrum v2.0, TeleMini v2.0 and EasyMini
99 and fixes bugs in AltosUI and the AltOS firmware.
103 <revnumber>1.2.1</revnumber>
104 <date>21 May 2013</date>
106 Updated for software version 1.2. Version 1.2 adds support
107 for TeleBT and AltosDroid. It also adds a few minor features
108 and fixes bugs in AltosUI and the AltOS firmware.
112 <revnumber>1.2</revnumber>
113 <date>18 April 2013</date>
115 Updated for software version 1.2. Version 1.2 adds support
116 for MicroPeak and the MicroPeak USB interface.
120 <revnumber>1.1.1</revnumber>
121 <date>16 September 2012</date>
123 Updated for software version 1.1.1 Version 1.1.1 fixes a few
124 bugs found in version 1.1.
128 <revnumber>1.1</revnumber>
129 <date>13 September 2012</date>
131 Updated for software version 1.1. Version 1.1 has new
132 features but is otherwise compatible with version 1.0.
136 <revnumber>1.0</revnumber>
137 <date>24 August 2011</date>
139 Updated for software version 1.0. Note that 1.0 represents a
140 telemetry format change, meaning both ends of a link
141 (TeleMetrum/TeleMini and TeleDongle) must be updated or
142 communications will fail.
146 <revnumber>0.9</revnumber>
147 <date>18 January 2011</date>
149 Updated for software version 0.9. Note that 0.9 represents a
150 telemetry format change, meaning both ends of a link (TeleMetrum and
151 TeleDongle) must be updated or communications will fail.
155 <revnumber>0.8</revnumber>
156 <date>24 November 2010</date>
157 <revremark>Updated for software version 0.8 </revremark>
162 <title>Acknowledgments</title>
164 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing “The
165 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
166 Kit” which formed the basis of the original Getting Started chapter
167 in this manual. Bob was one of our first customers for a production
168 TeleMetrum, and his continued enthusiasm and contributions
169 are immensely gratifying and highly appreciated!
172 And thanks to Anthony (AJ) Towns for major contributions including
173 the AltosUI graphing and site map code and associated documentation.
174 Free software means that our customers and friends can become our
175 collaborators, and we certainly appreciate this level of
179 Have fun using these products, and we hope to meet all of you
180 out on the rocket flight line somewhere.
183 NAR #87103, TRA #12201
185 Keith Packard, KD7SQG
186 NAR #88757, TRA #12200
191 <title>Introduction and Overview</title>
193 Welcome to the Altus Metrum community! Our circuits and software reflect
194 our passion for both hobby rocketry and Free Software. We hope their
195 capabilities and performance will delight you in every way, but by
196 releasing all of our hardware and software designs under open licenses,
197 we also hope to empower you to take as active a role in our collective
201 The first device created for our community was TeleMetrum, a dual
202 deploy altimeter with fully integrated GPS and radio telemetry
203 as standard features, and a “companion interface” that will
204 support optional capabilities in the future. The latest version
205 of TeleMetrum, v2.0, has all of the same features but with
206 improved sensors and radio to offer increased performance.
209 Our second device was TeleMini, a dual deploy altimeter with
210 radio telemetry and radio direction finding. The first version
211 of this device was only 13mm by 38mm (½ inch by 1½ inches) and
212 could fit easily in an 18mm air-frame. The latest version, v2.0,
213 includes a beeper, USB data download and extended on-board
214 flight logging, along with an improved barometric sensor.
217 TeleMega is our most sophisticated device, including six pyro
218 channels (four of which are fully programmable), integrated GPS,
219 integrated gyroscopes for staging/air-start inhibit and high
220 performance telemetry.
223 EasyMini is a dual-deploy altimeter with logging and built-in
227 EasyMega is essentially a TeleMega board with the GPS receiver
228 and telemetry transmitter removed. It offers the same 6 pyro
229 channels and integrated gyroscopes for staging/air-start inhibit.
232 TeleDongle v0.2 was our first ground station, providing a USB to RF
233 interfaces for communicating with the altimeters. Combined with
234 your choice of antenna and notebook computer, TeleDongle and our
235 associated user interface software form a complete ground
236 station capable of logging and displaying in-flight telemetry,
237 aiding rocket recovery, then processing and archiving flight
238 data for analysis and review. The latest version, TeleDongle
239 v3, has all new electronics with a higher performance radio
243 For a slightly more portable ground station experience that also
244 provides direct rocket recovery support, TeleBT offers flight
245 monitoring and data logging using a Bluetooth™ connection between
246 the receiver and an Android device that has the AltosDroid
247 application installed from the Google Play store.
250 More products will be added to the Altus Metrum family over time, and
251 we currently envision that this will be a single, comprehensive manual
252 for the entire product family.
256 <title>Getting Started</title>
258 The first thing to do after you check the inventory of parts in your
259 “starter kit” is to charge the battery.
262 For TeleMetrum, TeleMega and EasyMega, the battery can be charged by plugging it into the
263 corresponding socket of the device and then using the USB
264 cable to plug the flight computer into your computer's USB socket. The
265 on-board circuitry will charge the battery whenever it is plugged
266 in, because the on-off switch does NOT control the
270 On TeleMetrum v1 boards, when the GPS chip is initially
271 searching for satellites, TeleMetrum will consume more current
272 than it pulls from the USB port, so the battery must be
273 attached in order to get satellite lock. Once GPS is locked,
274 the current consumption goes back down enough to enable charging
275 while running. So it's a good idea to fully charge the battery
276 as your first item of business so there is no issue getting and
277 maintaining satellite lock. The yellow charge indicator led
278 will go out when the battery is nearly full and the charger goes
279 to trickle charge. It can take several hours to fully recharge a
280 deeply discharged battery.
283 TeleMetrum v2.0, TeleMega and EasyMega use a higher power battery charger,
284 allowing them to charge the battery while running the board at
285 maximum power. When the battery is charging, or when the board
286 is consuming a lot of power, the red LED will be lit. When the
287 battery is fully charged, the green LED will be lit. When the
288 battery is damaged or missing, both LEDs will be lit, which
292 The Lithium Polymer TeleMini and EasyMini battery can be charged by
293 disconnecting it from the board and plugging it into a
294 standalone battery charger such as the LipoCharger product
295 included in TeleMini Starter Kits, and connecting that via a USB
296 cable to a laptop or other USB power source.
299 You can also choose to use another battery with TeleMini v2.0
300 and EasyMini, anything supplying between 4 and 12 volts should
301 work fine (like a standard 9V battery), but if you are planning
302 to fire pyro charges, ground testing is required to verify that
303 the battery supplies enough current to fire your chosen e-matches.
306 The other active device in the starter kit is the TeleDongle USB to
307 RF interface. If you plug it in to your Mac or Linux computer it should
308 “just work”, showing up as a serial port device. Windows systems need
309 driver information that is part of the AltOS download to know that the
310 existing USB modem driver will work. We therefore recommend installing
311 our software before plugging in TeleDongle if you are using a Windows
312 computer. If you are using an older version of Linux and are having
313 problems, try moving to a fresher kernel (2.6.33 or newer).
316 Next you should obtain and install the AltOS software. The AltOS
317 distribution includes the AltosUI ground station program, current
319 images for all of the hardware, and a number of standalone
320 utilities that are rarely needed. Pre-built binary packages are
321 available for Linux, Microsoft Windows, and recent MacOSX
322 versions. Full source code and build instructions are also
323 available. The latest version may always be downloaded from
324 <ulink url="http://altusmetrum.org/AltOS"/>.
327 If you're using a TeleBT instead of the TeleDongle, you'll want to
328 install the AltosDroid application from the Google Play store on an
329 Android device. You don't need a data plan to use AltosDroid, but
330 without network access, the Map view will be less useful as it
331 won't contain any map data. You can also use TeleBT connected
332 over USB with your laptop computer; it acts exactly like a
333 TeleDongle. Anywhere this manual talks about TeleDongle, you can
334 also read that as 'and TeleBT when connected via USB'.
338 <title>Handling Precautions</title>
340 All Altus Metrum products are sophisticated electronic devices.
341 When handled gently and properly installed in an air-frame, they
342 will deliver impressive results. However, as with all electronic
343 devices, there are some precautions you must take.
346 The Lithium Polymer rechargeable batteries have an
347 extraordinary power density. This is great because we can fly with
348 much less battery mass than if we used alkaline batteries or previous
349 generation rechargeable batteries... but if they are punctured
350 or their leads are allowed to short, they can and will release their
352 Thus we recommend that you take some care when handling our batteries
353 and consider giving them some extra protection in your air-frame. We
354 often wrap them in suitable scraps of closed-cell packing foam before
355 strapping them down, for example.
358 The barometric sensors used on all of our flight computers are
359 sensitive to sunlight. In normal mounting situations, the baro sensor
360 and all of the other surface mount components
361 are “down” towards whatever the underlying mounting surface is, so
362 this is not normally a problem. Please consider this when designing an
363 installation in an air-frame with a see-through plastic payload bay. It
364 is particularly important to
365 consider this with TeleMini v1.0, both because the baro sensor is on the
366 “top” of the board, and because many model rockets with payload bays
367 use clear plastic for the payload bay! Replacing these with an opaque
368 cardboard tube, painting them, or wrapping them with a layer of masking
369 tape are all reasonable approaches to keep the sensor out of direct
373 The barometric sensor sampling port must be able to “breathe”,
374 both by not being covered by foam or tape or other materials that might
375 directly block the hole on the top of the sensor, and also by having a
376 suitable static vent to outside air.
379 As with all other rocketry electronics, Altus Metrum altimeters must
380 be protected from exposure to corrosive motor exhaust and ejection
385 <title>Altus Metrum Hardware</title>
387 <title>General Usage Instructions</title>
389 Here are general instructions for hooking up an Altus Metrum
390 flight computer. Instructions specific to each model will be
391 found in the section devoted to that model below.
394 To prevent electrical interference from affecting the
395 operation of the flight computer, it's important to always
396 twist pairs of wires connected to the board. Twist the switch
397 leads, the pyro leads and the battery leads. This reduces
398 interference through a mechanism called common mode rejection.
401 <title>Hooking Up Lithium Polymer Batteries</title>
403 All Altus Metrum flight computers have a two pin JST PH
404 series connector to connect up a single-cell Lithium Polymer
405 cell (3.7V nominal). You can purchase matching batteries
406 from the Altus Metrum store, or other vendors, or you can
407 make your own. Pin 1 of the connector is positive, pin 2 is
408 negative. Spark Fun sells a cable with the connector
409 attached, which they call a <ulink
410 url="https://www.sparkfun.com/products/9914">JST Jumper 2
411 Wire Assembly</ulink>.
414 Many RC vendors also sell lithium polymer batteries with
415 this same connector. All that we have found use the opposite
416 polarity, and if you use them that way, you will damage or
417 destroy the flight computer.
421 <title>Hooking Up Pyro Charges</title>
423 Altus Metrum flight computers always have two screws for
424 each pyro charge. This means you shouldn't need to put two
425 wires into a screw terminal or connect leads from pyro
426 charges together externally.
429 On the flight computer, one lead from each charge is hooked
430 to the positive battery terminal through the power switch.
431 The other lead is connected through the pyro circuit, which
432 is connected to the negative battery terminal when the pyro
437 <title>Hooking Up a Power Switch</title>
439 Altus Metrum flight computers need an external power switch
440 to turn them on. This disconnects both the computer and the
441 pyro charges from the battery, preventing the charges from
442 firing when in the Off position. The switch is in-line with
443 the positive battery terminal.
446 <title>Using an External Active Switch Circuit</title>
448 You can use an active switch circuit, such as the
449 Featherweight Magnetic Switch, with any Altus Metrum
450 flight computer. These require three connections, one to
451 the battery, one to the positive power input on the flight
452 computer and one to ground. Find instructions on how to
453 hook these up for each flight computer below. The follow
454 the instructions that come with your active switch to
460 <title>Using a Separate Pyro Battery</title>
462 As mentioned above in the section on hooking up pyro
463 charges, one lead for each of the pyro charges is connected
464 through the power switch directly to the positive battery
465 terminal. The other lead is connected to the pyro circuit,
466 which connects it to the negative battery terminal when the
467 pyro circuit is fired. The pyro circuit on all of the flight
468 computers is designed to handle up to 16V.
471 To use a separate pyro battery, connect the negative pyro
472 battery terminal to the flight computer ground terminal,
473 the positive battery terminal to the igniter and the other
474 igniter lead to the negative pyro terminal on the flight
475 computer. When the pyro channel fires, it will complete the
476 circuit between the negative pyro terminal and the ground
477 terminal, firing the igniter. Specific instructions on how
478 to hook this up will be found in each section below.
482 <title>Using a Different Kind of Battery</title>
484 EasyMini and TeleMini v2 are designed to use either a
485 lithium polymer battery or any other battery producing
486 between 4 and 12 volts, such as a rectangular 9V
487 battery. TeleMega, EasyMega and TeleMetrum are not designed for this,
488 and must only be powered by a lithium polymer battery. Find
489 instructions on how to use other batteries in the EasyMini
490 and TeleMini sections below.
495 <title>Specifications</title>
497 Here's the full set of Altus Metrum products, both in
498 production and retired.
501 <title>Altus Metrum Electronics</title>
502 <?dbfo keep-together="always"?>
503 <tgroup cols='8' align='center' colsep='1' rowsep='1'>
504 <colspec align='center' colwidth='*' colname='Device'/>
505 <colspec align='center' colwidth='*' colname='Barometer'/>
506 <colspec align='center' colwidth='*' colname='Z-axis accelerometer'/>
507 <colspec align='center' colwidth='*' colname='GPS'/>
508 <colspec align='center' colwidth='*' colname='3D sensors'/>
509 <colspec align='center' colwidth='*' colname='Storage'/>
510 <colspec align='center' colwidth='*' colname='RF'/>
511 <colspec align='center' colwidth='*' colname='Battery'/>
514 <entry align='center'>Device</entry>
515 <entry align='center'>Barometer</entry>
516 <entry align='center'>Z-axis accelerometer</entry>
517 <entry align='center'>GPS</entry>
518 <entry align='center'>3D sensors</entry>
519 <entry align='center'>Storage</entry>
520 <entry align='center'>RF Output</entry>
521 <entry align='center'>Battery</entry>
526 <entry>TeleMetrum v1.0</entry>
527 <entry><para>MP3H6115 10km (33k')</para></entry>
528 <entry><para>MMA2202 50g</para></entry>
529 <entry>SkyTraq</entry>
536 <entry>TeleMetrum v1.1</entry>
537 <entry><para>MP3H6115 10km (33k')</para></entry>
538 <entry><para>MMA2202 50g</para></entry>
539 <entry>SkyTraq</entry>
546 <entry>TeleMetrum v1.2</entry>
547 <entry><para>MP3H6115 10km (33k')</para></entry>
548 <entry><para>ADXL78 70g</para></entry>
549 <entry>SkyTraq</entry>
556 <entry>TeleMetrum v2.0</entry>
557 <entry><para>MS5607 30km (100k')</para></entry>
558 <entry><para>MMA6555 102g</para></entry>
559 <entry>uBlox Max-7Q</entry>
566 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
567 <entry><para>MP3H6115 10km (33k')</para></entry>
576 <entry>TeleMini <?linebreak?>v2.0</entry>
577 <entry><para>MS5607 30km (100k')</para></entry>
583 <entry>3.7-12V</entry>
586 <entry>EasyMini <?linebreak?>v1.0</entry>
587 <entry><para>MS5607 30km (100k')</para></entry>
593 <entry>3.7-12V</entry>
596 <entry>TeleMega <?linebreak?>v1.0</entry>
597 <entry><para>MS5607 30km (100k')</para></entry>
598 <entry><para>MMA6555 102g</para></entry>
599 <entry>uBlox Max-7Q</entry>
600 <entry><para>MPU6000 HMC5883</para></entry>
606 <entry>EasyMega <?linebreak?>v1.0</entry>
607 <entry><para>MS5607 30km (100k')</para></entry>
608 <entry><para>MMA6555 102g</para></entry>
610 <entry><para>MPU6000 HMC5883</para></entry>
619 <title>Altus Metrum Boards</title>
620 <?dbfo keep-together="always"?>
621 <tgroup cols='6' align='center' colsep='1' rowsep='1'>
622 <colspec align='center' colwidth='*' colname='Device'/>
623 <colspec align='center' colwidth='*' colname='Connectors'/>
624 <colspec align='center' colwidth='*' colname='Screw Terminals'/>
625 <colspec align='center' colwidth='*' colname='Width'/>
626 <colspec align='center' colwidth='*' colname='Length'/>
627 <colspec align='center' colwidth='*' colname='Tube Size'/>
630 <entry align='center'>Device</entry>
631 <entry align='center'>Connectors</entry>
632 <entry align='center'>Screw Terminals</entry>
633 <entry align='center'>Width</entry>
634 <entry align='center'>Length</entry>
635 <entry align='center'>Tube Size</entry>
640 <entry>TeleMetrum</entry>
644 Companion<?linebreak?>
648 <entry><para>Apogee pyro <?linebreak?>Main pyro <?linebreak?>Switch</para></entry>
649 <entry>1 inch (2.54cm)</entry>
650 <entry>2 ¾ inch (6.99cm)</entry>
651 <entry>29mm coupler</entry>
654 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
661 Apogee pyro <?linebreak?>
664 <entry>½ inch (1.27cm)</entry>
665 <entry>1½ inch (3.81cm)</entry>
666 <entry>18mm coupler</entry>
669 <entry>TeleMini <?linebreak?>v2.0</entry>
677 Apogee pyro <?linebreak?>
678 Main pyro <?linebreak?>
679 Battery <?linebreak?>
682 <entry>0.8 inch (2.03cm)</entry>
683 <entry>1½ inch (3.81cm)</entry>
684 <entry>24mm coupler</entry>
687 <entry>EasyMini</entry>
694 Apogee pyro <?linebreak?>
695 Main pyro <?linebreak?>
696 Battery <?linebreak?>
699 <entry>0.8 inch (2.03cm)</entry>
700 <entry>1½ inch (3.81cm)</entry>
701 <entry>24mm coupler</entry>
704 <entry>TeleMega</entry>
708 Companion<?linebreak?>
713 Apogee pyro <?linebreak?>
714 Main pyro<?linebreak?>
715 Pyro A-D<?linebreak?>
719 <entry>1¼ inch (3.18cm)</entry>
720 <entry>3¼ inch (8.26cm)</entry>
721 <entry>38mm coupler</entry>
724 <entry>EasyMega</entry>
727 Companion<?linebreak?>
732 Apogee pyro <?linebreak?>
733 Main pyro<?linebreak?>
734 Pyro A-D<?linebreak?>
738 <entry>1¼ inch (3.18cm)</entry>
739 <entry>2¼ inch (5.62cm)</entry>
740 <entry>38mm coupler</entry>
747 <title>TeleMetrum</title>
751 <imagedata fileref="telemetrum-v1.1-thside.jpg" width="5.5in" scalefit="1"/>
756 TeleMetrum is a 1 inch by 2¾ inch circuit board. It was designed to
757 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
758 small in diameter may require some creativity in mounting and wiring
759 to succeed! The presence of an accelerometer means TeleMetrum should
760 be aligned along the flight axis of the airframe, and by default the ¼
761 wave UHF wire antenna should be on the nose-cone end of the board. The
762 antenna wire is about 7 inches long, and wiring for a power switch and
763 the e-matches for apogee and main ejection charges depart from the
764 fin can end of the board, meaning an ideal “simple” avionics
765 bay for TeleMetrum should have at least 10 inches of interior length.
768 <title>TeleMetrum Screw Terminals</title>
770 TeleMetrum has six screw terminals on the end of the board
771 opposite the telemetry antenna. Two are for the power
772 switch, and two each for the apogee and main igniter
773 circuits. Using the picture above and starting from the top,
774 the terminals are as follows:
777 <title>TeleMetrum Screw Terminals</title>
778 <?dbfo keep-together="always"?>
779 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
780 <colspec align='center' colwidth='*' colname='Pin #'/>
781 <colspec align='center' colwidth='2*' colname='Pin Name'/>
782 <colspec align='left' colwidth='5*' colname='Description'/>
785 <entry align='center'>Terminal #</entry>
786 <entry align='center'>Terminal Name</entry>
787 <entry align='center'>Description</entry>
793 <entry>Switch Output</entry>
794 <entry>Switch connection to flight computer</entry>
798 <entry>Switch Input</entry>
799 <entry>Switch connection to positive battery terminal</entry>
803 <entry>Main +</entry>
804 <entry>Main pyro channel common connection to battery +</entry>
808 <entry>Main -</entry>
809 <entry>Main pyro channel connection to pyro circuit</entry>
813 <entry>Apogee +</entry>
814 <entry>Apogee pyro channel common connection to battery +</entry>
818 <entry>Apogee -</entry>
819 <entry>Apogee pyro channel connection to pyro circuit</entry>
826 <title>Using a Separate Pyro Battery with TeleMetrum</title>
828 As described above, using an external pyro battery involves
829 connecting the negative battery terminal to the flight
830 computer ground, connecting the positive battery terminal to
831 one of the igniter leads and connecting the other igniter
832 lead to the per-channel pyro circuit connection.
835 To connect the negative battery terminal to the TeleMetrum
836 ground, insert a small piece of wire, 24 to 28 gauge
837 stranded, into the GND hole just above the screw terminal
838 strip and solder it in place.
841 Connecting the positive battery terminal to the pyro
842 charges must be done separate from TeleMetrum, by soldering
843 them together or using some other connector.
846 The other lead from each pyro charge is then inserted into
847 the appropriate per-pyro channel screw terminal (terminal 4 for the
848 Main charge, terminal 6 for the Apogee charge).
852 <title>Using an Active Switch with TeleMetrum</title>
854 As explained above, an external active switch requires three
855 connections, one to the positive battery terminal, one to
856 the flight computer positive input and one to ground.
859 The positive battery terminal is available on screw terminal
860 2, the positive flight computer input is on terminal 1. To
861 hook a lead to ground, solder a piece of wire, 24 to 28
862 gauge stranded, to the GND hole just above terminal 1.
867 <title>TeleMini v1.0</title>
871 <imagedata fileref="telemini-v1-top.jpg" width="5.5in" scalefit="1"/>
876 TeleMini v1.0 is ½ inches by 1½ inches. It was
877 designed to fit inside an 18mm air-frame tube, but using it in
878 a tube that small in diameter may require some creativity in
879 mounting and wiring to succeed! Since there is no
880 accelerometer, TeleMini can be mounted in any convenient
881 orientation. The default ¼ wave UHF wire antenna attached to
882 the center of one end of the board is about 7 inches long. Two
883 wires for the power switch are connected to holes in the
884 middle of the board. Screw terminals for the e-matches for
885 apogee and main ejection charges depart from the other end of
886 the board, meaning an ideal “simple” avionics bay for TeleMini
887 should have at least 9 inches of interior length.
890 <title>TeleMini v1.0 Screw Terminals</title>
892 TeleMini v1.0 has four screw terminals on the end of the
893 board opposite the telemetry antenna. Two are for the apogee
894 and two are for main igniter circuits. There are also wires
895 soldered to the board for the power switch. Using the
896 picture above and starting from the top for the terminals
897 and from the left for the power switch wires, the
898 connections are as follows:
901 <title>TeleMini v1.0 Connections</title>
902 <?dbfo keep-together="always"?>
903 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
904 <colspec align='center' colwidth='*' colname='Pin #'/>
905 <colspec align='center' colwidth='2*' colname='Pin Name'/>
906 <colspec align='left' colwidth='5*' colname='Description'/>
909 <entry align='center'>Terminal #</entry>
910 <entry align='center'>Terminal Name</entry>
911 <entry align='center'>Description</entry>
917 <entry>Apogee -</entry>
918 <entry>Apogee pyro channel connection to pyro circuit</entry>
922 <entry>Apogee +</entry>
923 <entry>Apogee pyro channel common connection to battery +</entry>
927 <entry>Main -</entry>
928 <entry>Main pyro channel connection to pyro circuit</entry>
932 <entry>Main +</entry>
933 <entry>Main pyro channel common connection to battery +</entry>
937 <entry>Switch Output</entry>
938 <entry>Switch connection to flight computer</entry>
942 <entry>Switch Input</entry>
943 <entry>Switch connection to positive battery terminal</entry>
950 <title>Using a Separate Pyro Battery with TeleMini v1.0</title>
952 As described above, using an external pyro battery involves
953 connecting the negative battery terminal to the flight
954 computer ground, connecting the positive battery terminal to
955 one of the igniter leads and connecting the other igniter
956 lead to the per-channel pyro circuit connection. Because
957 there is no solid ground connection to use on TeleMini, this
961 The only available ground connection on TeleMini v1.0 are
962 the two mounting holes next to the telemetry
963 antenna. Somehow connect a small piece of wire to one of
964 those holes and hook it to the negative pyro battery terminal.
967 Connecting the positive battery terminal to the pyro
968 charges must be done separate from TeleMini v1.0, by soldering
969 them together or using some other connector.
972 The other lead from each pyro charge is then inserted into
973 the appropriate per-pyro channel screw terminal (terminal 3 for the
974 Main charge, terminal 1 for the Apogee charge).
978 <title>Using an Active Switch with TeleMini v1.0</title>
980 As explained above, an external active switch requires three
981 connections, one to the positive battery terminal, one to
982 the flight computer positive input and one to ground. Again,
983 because TeleMini doesn't have any good ground connection,
984 this is not recommended.
987 The positive battery terminal is available on the Right
988 power switch wire, the positive flight computer input is on
989 the left power switch wire. Hook a lead to either of the
990 mounting holes for a ground connection.
995 <title>TeleMini v2.0</title>
999 <imagedata fileref="telemini-v2-top.jpg" width="5.5in" scalefit="1"/>
1004 TeleMini v2.0 is 0.8 inches by 1½ inches. It adds more
1005 on-board data logging memory, a built-in USB connector and
1006 screw terminals for the battery and power switch. The larger
1007 board fits in a 24mm coupler. There's also a battery connector
1008 for a LiPo battery if you want to use one of those.
1011 <title>TeleMini v2.0 Screw Terminals</title>
1013 TeleMini v2.0 has two sets of four screw terminals on the end of the
1014 board opposite the telemetry antenna. Using the picture
1015 above, the top four have connections for the main pyro
1016 circuit and an external battery and the bottom four have
1017 connections for the apogee pyro circuit and the power
1018 switch. Counting from the left, the connections are as follows:
1021 <title>TeleMini v2.0 Connections</title>
1022 <?dbfo keep-together="always"?>
1023 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
1024 <colspec align='center' colwidth='*' colname='Pin #'/>
1025 <colspec align='center' colwidth='2*' colname='Pin Name'/>
1026 <colspec align='left' colwidth='5*' colname='Description'/>
1029 <entry align='center'>Terminal #</entry>
1030 <entry align='center'>Terminal Name</entry>
1031 <entry align='center'>Description</entry>
1036 <entry>Top 1</entry>
1037 <entry>Main -</entry>
1038 <entry>Main pyro channel connection to pyro circuit</entry>
1041 <entry>Top 2</entry>
1042 <entry>Main +</entry>
1043 <entry>Main pyro channel common connection to battery +</entry>
1046 <entry>Top 3</entry>
1047 <entry>Battery +</entry>
1048 <entry>Positive external battery terminal</entry>
1051 <entry>Top 4</entry>
1052 <entry>Battery -</entry>
1053 <entry>Negative external battery terminal</entry>
1056 <entry>Bottom 1</entry>
1057 <entry>Apogee -</entry>
1058 <entry>Apogee pyro channel connection to pyro circuit</entry>
1061 <entry>Bottom 2</entry>
1062 <entry>Apogee +</entry>
1063 <entry>Apogee pyro channel common connection to
1067 <entry>Bottom 3</entry>
1068 <entry>Switch Output</entry>
1069 <entry>Switch connection to flight computer</entry>
1072 <entry>Bottom 4</entry>
1073 <entry>Switch Input</entry>
1074 <entry>Switch connection to positive battery terminal</entry>
1081 <title>Using a Separate Pyro Battery with TeleMini v2.0</title>
1083 As described above, using an external pyro battery involves
1084 connecting the negative battery terminal to the flight
1085 computer ground, connecting the positive battery terminal to
1086 one of the igniter leads and connecting the other igniter
1087 lead to the per-channel pyro circuit connection.
1090 To connect the negative pyro battery terminal to TeleMini
1091 ground, connect it to the negative external battery
1092 connection, top terminal 4.
1095 Connecting the positive battery terminal to the pyro
1096 charges must be done separate from TeleMini v2.0, by soldering
1097 them together or using some other connector.
1100 The other lead from each pyro charge is then inserted into
1101 the appropriate per-pyro channel screw terminal (top
1102 terminal 1 for the Main charge, bottom terminal 1 for the
1107 <title>Using an Active Switch with TeleMini v2.0</title>
1109 As explained above, an external active switch requires three
1110 connections, one to the positive battery terminal, one to
1111 the flight computer positive input and one to ground. Use
1112 the negative external battery connection, top terminal 4 for
1116 The positive battery terminal is available on bottom
1117 terminal 4, the positive flight computer input is on the
1123 <title>EasyMini</title>
1127 <imagedata fileref="easymini-top.jpg" width="5.5in" scalefit="1"/>
1132 EasyMini is built on a 0.8 inch by 1½ inch circuit board. It's
1133 designed to fit in a 24mm coupler tube. The connectors and
1134 screw terminals match TeleMini v2.0, so you can easily swap between
1135 EasyMini and TeleMini.
1138 <title>EasyMini Screw Terminals</title>
1140 EasyMini has two sets of four screw terminals on the end of the
1141 board opposite the telemetry antenna. Using the picture
1142 above, the top four have connections for the main pyro
1143 circuit and an external battery and the bottom four have
1144 connections for the apogee pyro circuit and the power
1145 switch. Counting from the left, the connections are as follows:
1148 <title>EasyMini Connections</title>
1149 <?dbfo keep-together="always"?>
1150 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
1151 <colspec align='center' colwidth='*' colname='Pin #'/>
1152 <colspec align='center' colwidth='2*' colname='Pin Name'/>
1153 <colspec align='left' colwidth='5*' colname='Description'/>
1156 <entry align='center'>Terminal #</entry>
1157 <entry align='center'>Terminal Name</entry>
1158 <entry align='center'>Description</entry>
1163 <entry>Top 1</entry>
1164 <entry>Main -</entry>
1165 <entry>Main pyro channel connection to pyro circuit</entry>
1168 <entry>Top 2</entry>
1169 <entry>Main +</entry>
1170 <entry>Main pyro channel common connection to battery +</entry>
1173 <entry>Top 3</entry>
1174 <entry>Battery +</entry>
1175 <entry>Positive external battery terminal</entry>
1178 <entry>Top 4</entry>
1179 <entry>Battery -</entry>
1180 <entry>Negative external battery terminal</entry>
1183 <entry>Bottom 1</entry>
1184 <entry>Apogee -</entry>
1185 <entry>Apogee pyro channel connection to pyro circuit</entry>
1188 <entry>Bottom 2</entry>
1189 <entry>Apogee +</entry>
1190 <entry>Apogee pyro channel common connection to
1194 <entry>Bottom 3</entry>
1195 <entry>Switch Output</entry>
1196 <entry>Switch connection to flight computer</entry>
1199 <entry>Bottom 4</entry>
1200 <entry>Switch Input</entry>
1201 <entry>Switch connection to positive battery terminal</entry>
1208 <title>Using a Separate Pyro Battery with EasyMini</title>
1210 As described above, using an external pyro battery involves
1211 connecting the negative battery terminal to the flight
1212 computer ground, connecting the positive battery terminal to
1213 one of the igniter leads and connecting the other igniter
1214 lead to the per-channel pyro circuit connection.
1217 To connect the negative pyro battery terminal to TeleMini
1218 ground, connect it to the negative external battery
1219 connection, top terminal 4.
1222 Connecting the positive battery terminal to the pyro
1223 charges must be done separate from EasyMini, by soldering
1224 them together or using some other connector.
1227 The other lead from each pyro charge is then inserted into
1228 the appropriate per-pyro channel screw terminal (top
1229 terminal 1 for the Main charge, bottom terminal 1 for the
1234 <title>Using an Active Switch with EasyMini</title>
1236 As explained above, an external active switch requires three
1237 connections, one to the positive battery terminal, one to
1238 the flight computer positive input and one to ground. Use
1239 the negative external battery connection, top terminal 4 for
1243 The positive battery terminal is available on bottom
1244 terminal 4, the positive flight computer input is on the
1250 <title>TeleMega</title>
1254 <imagedata fileref="telemega-v1.0-top.jpg" width="5.5in" scalefit="1"/>
1259 TeleMega is a 1¼ inch by 3¼ inch circuit board. It was
1260 designed to easily fit in a 38mm coupler. Like TeleMetrum,
1261 TeleMega has an accelerometer and so it must be mounted so that
1262 the board is aligned with the flight axis. It can be mounted
1263 either antenna up or down.
1266 <title>TeleMega Screw Terminals</title>
1268 TeleMega has two sets of nine screw terminals on the end of
1269 the board opposite the telemetry antenna. They are as follows:
1272 <title>TeleMega Screw Terminals</title>
1273 <?dbfo keep-together="always"?>
1274 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
1275 <colspec align='center' colwidth='*' colname='Pin #'/>
1276 <colspec align='center' colwidth='2*' colname='Pin Name'/>
1277 <colspec align='left' colwidth='5*' colname='Description'/>
1280 <entry align='center'>Terminal #</entry>
1281 <entry align='center'>Terminal Name</entry>
1282 <entry align='center'>Description</entry>
1287 <entry>Top 1</entry>
1288 <entry>Switch Input</entry>
1289 <entry>Switch connection to positive battery terminal</entry>
1292 <entry>Top 2</entry>
1293 <entry>Switch Output</entry>
1294 <entry>Switch connection to flight computer</entry>
1297 <entry>Top 3</entry>
1299 <entry>Ground connection for use with external active switch</entry>
1302 <entry>Top 4</entry>
1303 <entry>Main -</entry>
1304 <entry>Main pyro channel connection to pyro circuit</entry>
1307 <entry>Top 5</entry>
1308 <entry>Main +</entry>
1309 <entry>Main pyro channel common connection to battery +</entry>
1312 <entry>Top 6</entry>
1313 <entry>Apogee -</entry>
1314 <entry>Apogee pyro channel connection to pyro circuit</entry>
1317 <entry>Top 7</entry>
1318 <entry>Apogee +</entry>
1319 <entry>Apogee pyro channel common connection to battery +</entry>
1322 <entry>Top 8</entry>
1324 <entry>D pyro channel connection to pyro circuit</entry>
1327 <entry>Top 9</entry>
1329 <entry>D pyro channel common connection to battery +</entry>
1332 <entry>Bottom 1</entry>
1334 <entry>Ground connection for negative pyro battery terminal</entry>
1337 <entry>Bottom 2</entry>
1339 <entry>Positive pyro battery terminal</entry>
1342 <entry>Bottom 3</entry>
1345 Power switch output. Use to connect main battery to
1350 <entry>Bottom 4</entry>
1352 <entry>A pyro channel connection to pyro circuit</entry>
1355 <entry>Bottom 5</entry>
1357 <entry>A pyro channel common connection to battery +</entry>
1360 <entry>Bottom 6</entry>
1362 <entry>B pyro channel connection to pyro circuit</entry>
1365 <entry>Bottom 7</entry>
1367 <entry>B pyro channel common connection to battery +</entry>
1370 <entry>Bottom 8</entry>
1372 <entry>C pyro channel connection to pyro circuit</entry>
1375 <entry>Bottom 9</entry>
1377 <entry>C pyro channel common connection to battery +</entry>
1384 <title>Using a Separate Pyro Battery with TeleMega</title>
1386 TeleMega provides explicit support for an external pyro
1387 battery. All that is required is to remove the jumper
1388 between the lipo terminal (Bottom 3) and the pyro terminal
1389 (Bottom 2). Then hook the negative pyro battery terminal to ground
1390 (Bottom 1) and the positive pyro battery to the pyro battery
1391 input (Bottom 2). You can then use the existing pyro screw
1392 terminals to hook up all of the pyro charges.
1396 <title>Using Only One Battery With TeleMega</title>
1398 Because TeleMega has built-in support for a separate pyro
1399 battery, if you want to fly with just one battery running
1400 both the computer and firing the charges, you need to
1401 connect the flight computer battery to the pyro
1402 circuit. TeleMega has two screw terminals for this—hook a
1403 wire from the Lipo terminal (Bottom 3) to the Pyro terminal
1408 <title>Using an Active Switch with TeleMega</title>
1410 As explained above, an external active switch requires three
1411 connections, one to the positive battery terminal, one to
1412 the flight computer positive input and one to ground.
1415 The positive battery terminal is available on Top terminal
1416 1, the positive flight computer input is on Top terminal
1417 2. Ground is on Top terminal 3.
1422 <title>EasyMega</title>
1426 <imagedata fileref="easymega-v1.0-top.jpg" width="4.5in" scalefit="1"/>
1431 EasyMega is a 1¼ inch by 2¼ inch circuit board. It was
1432 designed to easily fit in a 38mm coupler. Like TeleMetrum,
1433 EasyMega has an accelerometer and so it must be mounted so that
1434 the board is aligned with the flight axis. It can be mounted
1435 either antenna up or down.
1438 <title>EasyMega Screw Terminals</title>
1440 EasyMega has two sets of nine screw terminals on the end of
1441 the board opposite the telemetry antenna. They are as follows:
1444 <title>EasyMega Screw Terminals</title>
1445 <?dbfo keep-together="always"?>
1446 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
1447 <colspec align='center' colwidth='*' colname='Pin #'/>
1448 <colspec align='center' colwidth='2*' colname='Pin Name'/>
1449 <colspec align='left' colwidth='5*' colname='Description'/>
1452 <entry align='center'>Terminal #</entry>
1453 <entry align='center'>Terminal Name</entry>
1454 <entry align='center'>Description</entry>
1459 <entry>Top 1</entry>
1460 <entry>Switch Input</entry>
1461 <entry>Switch connection to positive battery terminal</entry>
1464 <entry>Top 2</entry>
1465 <entry>Switch Output</entry>
1466 <entry>Switch connection to flight computer</entry>
1469 <entry>Top 3</entry>
1471 <entry>Ground connection for use with external active switch</entry>
1474 <entry>Top 4</entry>
1475 <entry>Main -</entry>
1476 <entry>Main pyro channel connection to pyro circuit</entry>
1479 <entry>Top 5</entry>
1480 <entry>Main +</entry>
1481 <entry>Main pyro channel common connection to battery +</entry>
1484 <entry>Top 6</entry>
1485 <entry>Apogee -</entry>
1486 <entry>Apogee pyro channel connection to pyro circuit</entry>
1489 <entry>Top 7</entry>
1490 <entry>Apogee +</entry>
1491 <entry>Apogee pyro channel common connection to battery +</entry>
1494 <entry>Top 8</entry>
1496 <entry>D pyro channel connection to pyro circuit</entry>
1499 <entry>Top 9</entry>
1501 <entry>D pyro channel common connection to battery +</entry>
1504 <entry>Bottom 1</entry>
1506 <entry>Ground connection for negative pyro battery terminal</entry>
1509 <entry>Bottom 2</entry>
1511 <entry>Positive pyro battery terminal</entry>
1514 <entry>Bottom 3</entry>
1517 Power switch output. Use to connect main battery to
1522 <entry>Bottom 4</entry>
1524 <entry>A pyro channel connection to pyro circuit</entry>
1527 <entry>Bottom 5</entry>
1529 <entry>A pyro channel common connection to battery +</entry>
1532 <entry>Bottom 6</entry>
1534 <entry>B pyro channel connection to pyro circuit</entry>
1537 <entry>Bottom 7</entry>
1539 <entry>B pyro channel common connection to battery +</entry>
1542 <entry>Bottom 8</entry>
1544 <entry>C pyro channel connection to pyro circuit</entry>
1547 <entry>Bottom 9</entry>
1549 <entry>C pyro channel common connection to battery +</entry>
1556 <title>Using a Separate Pyro Battery with EasyMega</title>
1558 EasyMega provides explicit support for an external pyro
1559 battery. All that is required is to remove the jumper
1560 between the lipo terminal (Bottom 3) and the pyro terminal
1561 (Bottom 2). Then hook the negative pyro battery terminal to ground
1562 (Bottom 1) and the positive pyro battery to the pyro battery
1563 input (Bottom 2). You can then use the existing pyro screw
1564 terminals to hook up all of the pyro charges.
1568 <title>Using Only One Battery With EasyMega</title>
1570 Because EasyMega has built-in support for a separate pyro
1571 battery, if you want to fly with just one battery running
1572 both the computer and firing the charges, you need to
1573 connect the flight computer battery to the pyro
1574 circuit. EasyMega has two screw terminals for this—hook a
1575 wire from the Lipo terminal (Bottom 3) to the Pyro terminal
1580 <title>Using an Active Switch with EasyMega</title>
1582 As explained above, an external active switch requires three
1583 connections, one to the positive battery terminal, one to
1584 the flight computer positive input and one to ground.
1587 The positive battery terminal is available on Top terminal
1588 1, the positive flight computer input is on Top terminal
1589 2. Ground is on Top terminal 3.
1594 <title>Flight Data Recording</title>
1596 Each flight computer logs data at 100 samples per second
1597 during ascent and 10 samples per second during descent, except
1598 for TeleMini v1.0, which records ascent at 10 samples per
1599 second and descent at 1 sample per second. Data are logged to
1600 an on-board flash memory part, which can be partitioned into
1601 several equal-sized blocks, one for each flight.
1604 <title>Data Storage on Altus Metrum altimeters</title>
1605 <?dbfo keep-together="always"?>
1606 <tgroup cols='4' align='center' colsep='1' rowsep='1'>
1607 <colspec align='center' colwidth='*' colname='Device'/>
1608 <colspec align='center' colwidth='*' colname='Bytes per sample'/>
1609 <colspec align='center' colwidth='*' colname='Total storage'/>
1610 <colspec align='center' colwidth='*' colname='Minutes of
1614 <entry align='center'>Device</entry>
1615 <entry align='center'>Bytes per Sample</entry>
1616 <entry align='center'>Total Storage</entry>
1617 <entry align='center'>Minutes at Full Rate</entry>
1622 <entry>TeleMetrum v1.0</entry>
1628 <entry>TeleMetrum v1.1 v1.2</entry>
1634 <entry>TeleMetrum v2.0</entry>
1640 <entry>TeleMini v1.0</entry>
1646 <entry>TeleMini v2.0</entry>
1652 <entry>EasyMini</entry>
1658 <entry>TeleMega</entry>
1664 <entry>EasyMega</entry>
1673 The on-board flash is partitioned into separate flight logs,
1674 each of a fixed maximum size. Increase the maximum size of
1675 each log and you reduce the number of flights that can be
1676 stored. Decrease the size and you can store more flights.
1679 Configuration data is also stored in the flash memory on
1680 TeleMetrum v1.x, TeleMini and EasyMini. This consumes 64kB
1681 of flash space. This configuration space is not available
1682 for storing flight log data. TeleMetrum v2.0, TeleMega and EasyMega
1683 store configuration data in a bit of eeprom available within
1684 the processor chip, leaving that space available in flash for
1688 To compute the amount of space needed for a single flight, you
1689 can multiply the expected ascent time (in seconds) by 100
1690 times bytes-per-sample, multiply the expected descent time (in
1691 seconds) by 10 times the bytes per sample and add the two
1692 together. That will slightly under-estimate the storage (in
1693 bytes) needed for the flight. For instance, a TeleMetrum v2.0 flight spending
1694 20 seconds in ascent and 150 seconds in descent will take
1695 about (20 * 1600) + (150 * 160) = 56000 bytes of storage. You
1696 could store dozens of these flights in the on-board flash.
1699 The default size allows for several flights on each flight
1700 computer, except for TeleMini v1.0, which only holds data for a
1701 single flight. You can adjust the size.
1704 Altus Metrum flight computers will not overwrite existing
1705 flight data, so be sure to download flight data and erase it
1706 from the flight computer before it fills up. The flight
1707 computer will still successfully control the flight even if it
1708 cannot log data, so the only thing you will lose is the data.
1712 <title>Installation</title>
1714 A typical installation involves attaching
1715 only a suitable battery, a single pole switch for
1716 power on/off, and two pairs of wires connecting e-matches for the
1717 apogee and main ejection charges. All Altus Metrum products are
1718 designed for use with single-cell batteries with 3.7 volts
1719 nominal. TeleMini v2.0 and EasyMini may also be used with other
1720 batteries as long as they supply between 4 and 12 volts.
1723 The battery connectors are a standard 2-pin JST connector and
1724 match batteries sold by Spark Fun. These batteries are
1725 single-cell Lithium Polymer batteries that nominally provide 3.7
1726 volts. Other vendors sell similar batteries for RC aircraft
1727 using mating connectors, however the polarity for those is
1728 generally reversed from the batteries used by Altus Metrum
1729 products. In particular, the Tenergy batteries supplied for use
1730 in Featherweight flight computers are not compatible with Altus
1731 Metrum flight computers or battery chargers. <emphasis>Check
1732 polarity and voltage before connecting any battery not purchased
1733 from Altus Metrum or Spark Fun.</emphasis>
1736 By default, we use the unregulated output of the battery directly
1737 to fire ejection charges. This works marvelously with standard
1738 low-current e-matches like the J-Tek from MJG Technologies, and with
1739 Quest Q2G2 igniters. However, if you want or need to use a separate
1740 pyro battery, check out the “External Pyro Battery” section in this
1741 manual for instructions on how to wire that up. The altimeters are
1742 designed to work with an external pyro battery of no more than 15 volts.
1745 Ejection charges are wired directly to the screw terminal block
1746 at the aft end of the altimeter. You'll need a very small straight
1747 blade screwdriver for these screws, such as you might find in a
1748 jeweler's screwdriver set.
1751 Except for TeleMini v1.0, the flight computers also use the
1752 screw terminal block for the power switch leads. On TeleMini v1.0,
1753 the power switch leads are soldered directly to the board and
1754 can be connected directly to a switch.
1757 For most air-frames, the integrated antennas are more than
1758 adequate. However, if you are installing in a carbon-fiber or
1759 metal electronics bay which is opaque to RF signals, you may need to
1760 use off-board external antennas instead. In this case, you can
1761 replace the stock UHF antenna wire with an edge-launched SMA connector,
1762 and, on TeleMetrum v1, you can unplug the integrated GPS
1763 antenna and select an appropriate off-board GPS antenna with
1764 cable terminating in a U.FL connector.
1769 <title>System Operation</title>
1771 <title>Firmware Modes </title>
1773 The AltOS firmware build for the altimeters has two
1774 fundamental modes, “idle” and “flight”. Which of these modes
1775 the firmware operates in is determined at start up time. For
1776 TeleMetrum, TeleMega and EasyMega, which have accelerometers, the mode is
1777 controlled by the orientation of the
1778 rocket (well, actually the board, of course...) at the time
1779 power is switched on. If the rocket is “nose up”, then
1780 the flight computer assumes it's on a rail or rod being prepared for
1781 launch, so the firmware chooses flight mode. However, if the
1782 rocket is more or less horizontal, the firmware instead enters
1783 idle mode. Since TeleMini v2.0 and EasyMini don't have an
1784 accelerometer we can use to determine orientation, “idle” mode
1785 is selected if the board is connected via USB to a computer,
1786 otherwise the board enters “flight” mode. TeleMini v1.0
1787 selects “idle” mode if it receives a command packet within the
1788 first five seconds of operation.
1791 At power on, the altimeter will beep out the battery voltage
1792 to the nearest tenth of a volt. Each digit is represented by
1793 a sequence of short “dit” beeps, with a pause between
1794 digits. A zero digit is represented with one long “dah”
1795 beep. Then there will be a short pause while the altimeter
1796 completes initialization and self test, and decides which mode
1800 Here's a short summary of all of the modes and the beeping (or
1801 flashing, in the case of TeleMini v1) that accompanies each
1802 mode. In the description of the beeping pattern, “dit” means a
1803 short beep while "dah" means a long beep (three times as
1804 long). “Brap” means a long dissonant tone.
1806 <title>AltOS Modes</title>
1807 <?dbfo keep-together="always"?>
1808 <tgroup cols='4' align='center' colsep='1' rowsep='1'>
1809 <colspec align='center' colwidth='*' colname='Mode Name'/>
1810 <colspec align='center' colwidth='*' colname='Letter'/>
1811 <colspec align='center' colwidth='*' colname='Beeps'/>
1812 <colspec align='center' colwidth='*' colname='Description'/>
1815 <entry>Mode Name</entry>
1816 <entry>Abbreviation</entry>
1817 <entry>Beeps</entry>
1818 <entry>Description</entry>
1823 <entry>Startup</entry>
1825 <entry>battery voltage in decivolts</entry>
1828 Calibrating sensors, detecting orientation.
1835 <entry>dit dit</entry>
1838 Ready to accept commands over USB or radio link.
1845 <entry>dit dah dah dit</entry>
1848 Waiting for launch. Not listening for commands.
1853 <entry>Boost</entry>
1855 <entry>dah dit dit dit</entry>
1858 Accelerating upwards.
1865 <entry>dit dit dah dit</entry>
1868 Decelerating, but moving faster than 200m/s.
1873 <entry>Coast</entry>
1875 <entry>dah dit dah dit</entry>
1878 Decelerating, moving slower than 200m/s
1883 <entry>Drogue</entry>
1885 <entry>dah dit dit</entry>
1888 Descending after apogee. Above main height.
1895 <entry>dah dah</entry>
1898 Descending. Below main height.
1903 <entry>Landed</entry>
1905 <entry>dit dah dit dit</entry>
1908 Stable altitude for at least ten seconds.
1913 <entry>Sensor error</entry>
1915 <entry>dah dit dit dah</entry>
1918 Error detected during sensor calibration.
1927 In flight or “pad” mode, the altimeter engages the flight
1928 state machine, goes into transmit-only mode to send telemetry,
1929 and waits for launch to be detected. Flight mode is indicated
1930 by an “di-dah-dah-dit” (“P” for pad) on the beeper or lights,
1931 followed by beeps or flashes indicating the state of the
1932 pyrotechnic igniter continuity. One beep/flash indicates
1933 apogee continuity, two beeps/flashes indicate main continuity,
1934 three beeps/flashes indicate both apogee and main continuity,
1935 and one longer “brap” sound which is made by rapidly
1936 alternating between two tones indicates no continuity. For a
1937 dual deploy flight, make sure you're getting three beeps or
1938 flashes before launching! For apogee-only or motor eject
1939 flights, do what makes sense.
1942 If idle mode is entered, you will hear an audible “di-dit” or
1943 see two short flashes (“I” for idle), and the flight state
1944 machine is disengaged, thus no ejection charges will fire.
1945 The altimeters also listen for the radio link when in idle
1946 mode for requests sent via TeleDongle. Commands can be issued
1947 in idle mode over either USB or the radio link
1948 equivalently. TeleMini v1.0 only has the radio link. Idle
1949 mode is useful for configuring the altimeter, for extracting
1950 data from the on-board storage chip after flight, and for
1951 ground testing pyro charges.
1954 In “Idle” and “Pad” modes, once the mode indication
1955 beeps/flashes and continuity indication has been sent, if
1956 there is no space available to log the flight in on-board
1957 memory, the flight computer will emit a warbling tone (much
1958 slower than the “no continuity tone”)
1961 Here's a summary of all of the “pad” and “idle” mode indications.
1963 <title>Pad/Idle Indications</title>
1964 <?dbfo keep-together="always"?>
1965 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
1966 <colspec align='center' colwidth='*' colname='Name'/>
1967 <colspec align='center' colwidth='*' colname='Beeps'/>
1968 <colspec align='center' colwidth='*' colname='Description'/>
1972 <entry>Beeps</entry>
1973 <entry>Description</entry>
1978 <entry>Neither</entry>
1982 No continuity detected on either apogee or main
1988 <entry>Apogee</entry>
1992 Continuity detected only on apogee igniter.
1998 <entry>dit dit</entry>
2001 Continuity detected only on main igniter.
2007 <entry>dit dit dit</entry>
2010 Continuity detected on both igniters.
2015 <entry>Storage Full</entry>
2016 <entry>warble</entry>
2019 On-board data logging storage is full. This will
2020 not prevent the flight computer from safely
2021 controlling the flight or transmitting telemetry
2022 signals, but no record of the flight will be
2023 stored in on-board flash.
2032 Once landed, the flight computer will signal that by emitting
2033 the “Landed” sound described above, after which it will beep
2034 out the apogee height (in meters). Each digit is represented
2035 by a sequence of short “dit” beeps, with a pause between
2036 digits. A zero digit is represented with one long “dah”
2037 beep. The flight computer will continue to report landed mode
2038 and beep out the maximum height until turned off.
2041 One “neat trick” of particular value when TeleMetrum, TeleMega
2042 or EasyMega are used with
2043 very large air-frames, is that you can power the board up while the
2044 rocket is horizontal, such that it comes up in idle mode. Then you can
2045 raise the air-frame to launch position, and issue a 'reset' command
2046 via TeleDongle over the radio link to cause the altimeter to reboot and
2047 come up in flight mode. This is much safer than standing on the top
2048 step of a rickety step-ladder or hanging off the side of a launch
2049 tower with a screw-driver trying to turn on your avionics before
2050 installing igniters!
2053 TeleMini v1.0 is configured solely via the radio link. Of course, that
2054 means you need to know the TeleMini radio configuration values
2055 or you won't be able to communicate with it. For situations
2056 when you don't have the radio configuration values, TeleMini v1.0
2057 offers an 'emergency recovery' mode. In this mode, TeleMini is
2058 configured as follows:
2062 Sets the radio frequency to 434.550MHz
2067 Sets the radio calibration back to the factory value.
2072 Sets the callsign to N0CALL
2077 Does not go to 'pad' mode after five seconds.
2083 To get into 'emergency recovery' mode, first find the row of
2084 four small holes opposite the switch wiring. Using a short
2085 piece of small gauge wire, connect the outer two holes
2086 together, then power TeleMini up. Once the red LED is lit,
2087 disconnect the wire and the board should signal that it's in
2088 'idle' mode after the initial five second startup period.
2094 TeleMetrum and TeleMega include a complete GPS receiver. A
2095 complete explanation of how GPS works is beyond the scope of
2096 this manual, but the bottom line is that the GPS receiver
2097 needs to lock onto at least four satellites to obtain a solid
2098 3 dimensional position fix and know what time it is.
2101 The flight computers provide backup power to the GPS chip any time a
2102 battery is connected. This allows the receiver to “warm start” on
2103 the launch rail much faster than if every power-on were a GPS
2104 “cold start”. In typical operations, powering up
2105 on the flight line in idle mode while performing final air-frame
2106 preparation will be sufficient to allow the GPS receiver to cold
2107 start and acquire lock. Then the board can be powered down during
2108 RSO review and installation on a launch rod or rail. When the board
2109 is turned back on, the GPS system should lock very quickly, typically
2110 long before igniter installation and return to the flight line are
2115 <title>Controlling An Altimeter Over The Radio Link</title>
2117 One of the unique features of the Altus Metrum system is the
2118 ability to create a two way command link between TeleDongle
2119 and an altimeter using the digital radio transceivers
2120 built into each device. This allows you to interact with the
2121 altimeter from afar, as if it were directly connected to the
2125 Any operation which can be performed with a flight computer can
2126 either be done with the device directly connected to the
2127 computer via the USB cable, or through the radio
2128 link. TeleMini v1.0 doesn't provide a USB connector and so it is
2129 always communicated with over radio. Select the appropriate
2130 TeleDongle device when the list of devices is presented and
2131 AltosUI will interact with an altimeter over the radio link.
2134 One oddity in the current interface is how AltosUI selects the
2135 frequency for radio communications. Instead of providing
2136 an interface to specifically configure the frequency, it uses
2137 whatever frequency was most recently selected for the target
2138 TeleDongle device in Monitor Flight mode. If you haven't ever
2139 used that mode with the TeleDongle in question, select the
2140 Monitor Flight button from the top level UI, and pick the
2141 appropriate TeleDongle device. Once the flight monitoring
2142 window is open, select the desired frequency and then close it
2143 down again. All radio communications will now use that frequency.
2148 Save Flight Data—Recover flight data from the rocket without
2154 Configure altimeter apogee delays, main deploy heights
2155 and additional pyro event conditions
2156 to respond to changing launch conditions. You can also
2157 'reboot' the altimeter. Use this to remotely enable the
2158 flight computer by turning TeleMetrum or TeleMega on in “idle” mode,
2159 then once the air-frame is oriented for launch, you can
2160 reboot the altimeter and have it restart in pad mode
2161 without having to climb the scary ladder.
2166 Fire Igniters—Test your deployment charges without snaking
2167 wires out through holes in the air-frame. Simply assemble the
2168 rocket as if for flight with the apogee and main charges
2169 loaded, then remotely command the altimeter to fire the
2175 Operation over the radio link for configuring an altimeter, ground
2176 testing igniters, and so forth uses the same RF frequencies as flight
2177 telemetry. To configure the desired TeleDongle frequency, select
2178 the monitor flight tab, then use the frequency selector and
2179 close the window before performing other desired radio operations.
2182 The flight computers only enable radio commanding in 'idle' mode.
2183 TeleMetrum and TeleMega use the accelerometer to detect which orientation they
2184 start up in, so make sure you have the flight computer lying horizontally when you turn
2185 it on. Otherwise, it will start in 'pad' mode ready for
2186 flight, and will not be listening for command packets from TeleDongle.
2189 TeleMini listens for a command packet for five seconds after
2190 first being turned on, if it doesn't hear anything, it enters
2191 'pad' mode, ready for flight and will no longer listen for
2192 command packets. The easiest way to connect to TeleMini is to
2193 initiate the command and select the TeleDongle device. At this
2194 point, the TeleDongle will be attempting to communicate with
2195 the TeleMini. Now turn TeleMini on, and it should immediately
2196 start communicating with the TeleDongle and the desired
2197 operation can be performed.
2200 You can monitor the operation of the radio link by watching the
2201 lights on the devices. The red LED will flash each time a packet
2202 is transmitted, while the green LED will light up on TeleDongle when
2203 it is waiting to receive a packet from the altimeter.
2207 <title>Ground Testing </title>
2209 An important aspect of preparing a rocket using electronic deployment
2210 for flight is ground testing the recovery system. Thanks
2211 to the bi-directional radio link central to the Altus Metrum system,
2212 this can be accomplished in a TeleMega, TeleMetrum or TeleMini equipped rocket
2213 with less work than you may be accustomed to with other systems. It
2217 Just prep the rocket for flight, then power up the altimeter
2218 in “idle” mode (placing air-frame horizontal for TeleMetrum or TeleMega, or
2219 selecting the Configure Altimeter tab for TeleMini). This will cause
2220 the firmware to go into “idle” mode, in which the normal flight
2221 state machine is disabled and charges will not fire without
2222 manual command. You can now command the altimeter to fire the apogee
2223 or main charges from a safe distance using your computer and
2224 TeleDongle and the Fire Igniter tab to complete ejection testing.
2228 <title>Radio Link </title>
2230 Our flight computers all incorporate an RF transceiver, but
2231 it's not a full duplex system... each end can only be transmitting or
2232 receiving at any given moment. So we had to decide how to manage the
2236 By design, the altimeter firmware listens for the radio link when
2237 it's in “idle mode”, which
2238 allows us to use the radio link to configure the rocket, do things like
2239 ejection tests, and extract data after a flight without having to
2240 crack open the air-frame. However, when the board is in “flight
2241 mode”, the altimeter only
2242 transmits and doesn't listen at all. That's because we want to put
2243 ultimate priority on event detection and getting telemetry out of
2245 the radio in case the rocket crashes and we aren't able to extract
2249 We don't generally use a 'normal packet radio' mode like APRS
2250 because they're just too inefficient. The GFSK modulation we
2251 use is FSK with the base-band pulses passed through a Gaussian
2252 filter before they go into the modulator to limit the
2253 transmitted bandwidth. When combined with forward error
2254 correction and interleaving, this allows us to have a very
2255 robust 19.2 kilobit data link with only 10-40 milliwatts of
2256 transmit power, a whip antenna in the rocket, and a hand-held
2257 Yagi on the ground. We've had flights to above 21k feet AGL
2258 with great reception, and calculations suggest we should be
2259 good to well over 40k feet AGL with a 5-element yagi on the
2260 ground with our 10mW units and over 100k feet AGL with the
2261 40mW devices. We hope to fly boards to higher altitudes over
2262 time, and would of course appreciate customer feedback on
2263 performance in higher altitude flights!
2269 TeleMetrum v2.0 and TeleMega can send APRS if desired, and the
2270 interval between APRS packets can be configured. As each APRS
2271 packet takes a full second to transmit, we recommend an
2272 interval of at least 5 seconds to avoid consuming too much
2273 battery power or radio channel bandwidth. You can configure
2274 the APRS interval using AltosUI; that process is described in
2275 the Configure Altimeter section of the AltosUI chapter.
2278 AltOS uses the APRS compressed position report data format,
2279 which provides for higher position precision and shorter
2280 packets than the original APRS format. It also includes
2281 altitude data, which is invaluable when tracking rockets. We
2282 haven't found a receiver which doesn't handle compressed
2283 positions, but it's just possible that you have one, so if you
2284 have an older device that can receive the raw packets but
2285 isn't displaying position information, it's possible that this
2289 APRS packets include an SSID (Secondary Station Identifier)
2290 field that allows one operator to have multiple
2291 transmitters. AltOS allows you to set this to a single digit
2292 from 0 to 9, allowing you to fly multiple transmitters at the
2293 same time while keeping the identify of each one separate in
2294 the receiver. By default, the SSID is set to the last digit of
2295 the device serial number.
2298 The APRS packet format includes a comment field that can have
2299 arbitrary text in it. AltOS uses this to send status
2300 information about the flight computer. It sends four fields as
2301 shown in the following table.
2304 <title>Altus Metrum APRS Comments</title>
2305 <?dbfo keep-together="always"?>
2306 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
2307 <colspec align='center' colwidth='*' colname='Field'/>
2308 <colspec align='center' colwidth='*' colname='Example'/>
2309 <colspec align='center' colwidth='4*' colname='Description'/>
2312 <entry align='center'>Field</entry>
2313 <entry align='center'>Example</entry>
2314 <entry align='center'>Description</entry>
2321 <entry>GPS Status U for unlocked, L for locked</entry>
2326 <entry>Number of Satellites in View</entry>
2331 <entry>Altimeter Battery Voltage</entry>
2336 <entry>Apogee Igniter Voltage</entry>
2341 <entry>Main Igniter Voltage</entry>
2346 <entry>Device Serial Number</entry>
2352 Here's an example of an APRS comment showing GPS lock with 6
2353 satellites in view, a primary battery at 4.0V, and
2354 apogee and main igniters both at 3.7V from device 1286.
2356 L6 B4.0 A3.7 M3.7 1286
2360 Make sure your primary battery is above 3.8V, any connected
2361 igniters are above 3.5V and GPS is locked with at least 5 or 6
2362 satellites in view before flying. If GPS is switching between
2363 L and U regularly, then it doesn't have a good lock and you
2364 should wait until it becomes stable.
2367 If the GPS receiver loses lock, the APRS data transmitted will
2368 contain the last position for which GPS lock was
2369 available. You can tell that this has happened by noticing
2370 that the GPS status character switches from 'L' to 'U'. Before
2371 GPS has locked, APRS will transmit zero for latitude,
2372 longitude and altitude.
2376 <title>Configurable Parameters</title>
2378 Configuring an Altus Metrum altimeter for flight is very
2379 simple. Even on our baro-only TeleMini and EasyMini boards,
2380 the use of a Kalman filter means there is no need to set a
2381 “mach delay”. The few configurable parameters can all be set
2382 using AltosUI over USB or or radio link via TeleDongle. Read
2383 the Configure Altimeter section in the AltosUI chapter below
2384 for more information.
2387 <title>Radio Frequency</title>
2389 Altus Metrum boards support radio frequencies in the 70cm
2390 band. By default, the configuration interface provides a
2391 list of 10 “standard” frequencies in 100kHz channels starting at
2392 434.550MHz. However, the firmware supports use of
2393 any 50kHz multiple within the 70cm band. At any given
2394 launch, we highly recommend coordinating when and by whom each
2395 frequency will be used to avoid interference. And of course, both
2396 altimeter and TeleDongle must be configured to the same
2397 frequency to successfully communicate with each other.
2401 <title>Callsign</title>
2403 This sets the callsign used for telemetry, APRS and the
2404 packet link. For telemetry and APRS, this is used to
2405 identify the device. For the packet link, the callsign must
2406 match that configured in AltosUI or the link will not
2407 work. This is to prevent accidental configuration of another
2408 Altus Metrum flight computer operating on the same frequency nearby.
2412 <title>Telemetry/RDF/APRS Enable</title>
2414 You can completely disable the radio while in flight, if
2415 necessary. This doesn't disable the packet link in idle
2420 <title>Telemetry baud rate</title>
2422 This sets the modulation bit rate for data transmission for
2423 both telemetry and packet link mode. Lower bit
2424 rates will increase range while reducing the amount of data
2425 that can be sent and increasing battery consumption. All
2426 telemetry is done using a rate 1/2 constraint 4 convolution
2427 code, so the actual data transmission rate is 1/2 of the
2428 modulation bit rate specified here.
2432 <title>APRS Interval</title>
2434 This selects how often APRS packets are transmitted. Set
2435 this to zero to disable APRS without also disabling the
2436 regular telemetry and RDF transmissions. As APRS takes a
2437 full second to transmit a single position report, we
2438 recommend sending packets no more than once every 5 seconds.
2442 <title>APRS SSID</title>
2444 This selects the SSID reported in APRS packets. By default,
2445 it is set to the last digit of the serial number, but you
2446 can change this to any value from 0 to 9.
2450 <title>Apogee Delay</title>
2452 Apogee delay is the number of seconds after the altimeter detects flight
2453 apogee that the drogue charge should be fired. In most cases, this
2454 should be left at the default of 0. However, if you are flying
2455 redundant electronics such as for an L3 certification, you may wish
2456 to set one of your altimeters to a positive delay so that both
2457 primary and backup pyrotechnic charges do not fire simultaneously.
2460 The Altus Metrum apogee detection algorithm fires exactly at
2461 apogee. If you are also flying an altimeter like the
2462 PerfectFlite MAWD, which only supports selecting 0 or 1
2463 seconds of apogee delay, you may wish to set the MAWD to 0
2464 seconds delay and set the TeleMetrum to fire your backup 2
2465 or 3 seconds later to avoid any chance of both charges
2466 firing simultaneously. We've flown several air-frames this
2467 way quite happily, including Keith's successful L3 cert.
2471 <title>Apogee Lockout</title>
2473 Apogee lockout is the number of seconds after boost where
2474 the flight computer will not fire the apogee charge, even if
2475 the rocket appears to be at apogee. This is often called
2476 'Mach Delay', as it is intended to prevent a flight computer
2477 from unintentionally firing apogee charges due to the pressure
2478 spike that occurrs across a mach transition. Altus Metrum
2479 flight computers include a Kalman filter which is not fooled
2480 by this sharp pressure increase, and so this setting should
2481 be left at the default value of zero to disable it.
2485 <title>Main Deployment Altitude</title>
2487 By default, the altimeter will fire the main deployment charge at an
2488 elevation of 250 meters (about 820 feet) above ground. We think this
2489 is a good elevation for most air-frames, but feel free to change this
2490 to suit. In particular, if you are flying two altimeters, you may
2492 deployment elevation for the backup altimeter to be something lower
2493 than the primary so that both pyrotechnic charges don't fire
2498 <title>Maximum Flight Log</title>
2500 Changing this value will set the maximum amount of flight
2501 log storage that an individual flight will use. The
2502 available storage is divided into as many flights of the
2503 specified size as can fit in the available space. You can
2504 download and erase individual flight logs. If you fill up
2505 the available storage, future flights will not get logged
2506 until you erase some of the stored ones.
2509 Even though our flight computers (except TeleMini v1.0) can store
2510 multiple flights, we strongly recommend downloading and saving
2511 flight data after each flight.
2515 <title>Ignite Mode</title>
2517 Instead of firing one charge at apogee and another charge at
2518 a fixed height above the ground, you can configure the
2519 altimeter to fire both at apogee or both during
2520 descent. This was added to support an airframe Bdale designed that
2521 had two altimeters, one in the fin can and one in the nose.
2524 Providing the ability to use both igniters for apogee or
2525 main allows some level of redundancy without needing two
2526 flight computers. In Redundant Apogee or Redundant Main
2527 mode, the two charges will be fired two seconds apart.
2531 <title>Pad Orientation</title>
2533 TeleMetrum, TeleMega and EasyMega measure acceleration along the axis
2534 of the board. Which way the board is oriented affects the
2535 sign of the acceleration value. Instead of trying to guess
2536 which way the board is mounted in the air frame, the
2537 altimeter must be explicitly configured for either Antenna
2538 Up or Antenna Down. The default, Antenna Up, expects the end
2539 of the board connected to the 70cm antenna to be nearest the
2540 nose of the rocket, with the end containing the screw
2541 terminals nearest the tail.
2545 <title>Configurable Pyro Channels</title>
2547 In addition to the usual Apogee and Main pyro channels,
2548 TeleMega and EasyMega have four additional channels that can be configured
2549 to activate when various flight conditions are
2550 satisfied. You can select as many conditions as necessary;
2551 all of them must be met in order to activate the
2552 channel. The conditions available are:
2557 Acceleration away from the ground. Select a value, and
2558 then choose whether acceleration should be above or
2559 below that value. Acceleration is positive upwards, so
2560 accelerating towards the ground would produce negative
2561 numbers. Acceleration during descent is noisy and
2562 inaccurate, so be careful when using it during these
2563 phases of the flight.
2568 Vertical speed. Select a value, and then choose whether
2569 vertical speed should be above or below that
2570 value. Speed is positive upwards, so moving towards the
2571 ground would produce negative numbers. Speed during
2572 descent is a bit noisy and so be careful when using it
2573 during these phases of the flight.
2578 Height. Select a value, and then choose whether the
2579 height above the launch pad should be above or below
2585 Orientation. TeleMega and EasyMega contain a 3-axis gyroscope and
2586 accelerometer which is used to measure the current
2587 angle. Note that this angle is not the change in angle
2588 from the launch pad, but rather absolute relative to
2589 gravity; the 3-axis accelerometer is used to compute the
2590 angle of the rocket on the launch pad and initialize the
2591 system. Because this value is computed by integrating
2592 rate gyros, it gets progressively less accurate as the
2593 flight goes on. It should have an accumulated error of
2594 less than 0.2°/second (after 10 seconds of flight, the
2595 error should be less than 2°).
2598 The usual use of the orientation configuration is to
2599 ensure that the rocket is traveling mostly upwards when
2600 deciding whether to ignite air starts or additional
2601 stages. For that, choose a reasonable maximum angle
2602 (like 20°) and set the motor igniter to require an angle
2603 of less than that value.
2608 Flight Time. Time since boost was detected. Select a
2609 value and choose whether to activate the pyro channel
2610 before or after that amount of time.
2615 Ascending. A simple test saying whether the rocket is
2616 going up or not. This is exactly equivalent to testing
2617 whether the speed is > 0.
2622 Descending. A simple test saying whether the rocket is
2623 going down or not. This is exactly equivalent to testing
2624 whether the speed is < 0.
2629 After Motor. The flight software counts each time the
2630 rocket starts accelerating and then decelerating
2631 (presumably due to a motor or motors burning). Use this
2632 value for multi-staged or multi-airstart launches.
2637 Delay. This value doesn't perform any checks, instead it
2638 inserts a delay between the time when the other
2639 parameters become true and when the pyro channel is
2645 Flight State. The flight software tracks the flight
2646 through a sequence of states:
2650 Boost. The motor has lit and the rocket is
2651 accelerating upwards.
2656 Fast. The motor has burned out and the rocket is
2657 decelerating, but it is going faster than 200m/s.
2662 Coast. The rocket is still moving upwards and
2663 decelerating, but the speed is less than 200m/s.
2668 Drogue. The rocket has reached apogee and is heading
2669 back down, but is above the configured Main
2675 Main. The rocket is still descending, and is below
2681 Landed. The rocket is no longer moving.
2687 You can select a state to limit when the pyro channel
2688 may activate; note that the check is based on when the
2689 rocket transitions <emphasis>into</emphasis> the state, and so checking for
2690 “greater than Boost” means that the rocket is currently
2691 in boost or some later state.
2694 When a motor burns out, the rocket enters either Fast or
2695 Coast state (depending on how fast it is moving). If the
2696 computer detects upwards acceleration again, it will
2697 move back to Boost state.
2706 <title>AltosUI</title>
2710 <imagedata fileref="altosui.png" width="4.6in"/>
2715 The AltosUI program provides a graphical user interface for
2716 interacting with the Altus Metrum product family. AltosUI can
2717 monitor telemetry data, configure devices and many other
2718 tasks. The primary interface window provides a selection of
2719 buttons, one for each major activity in the system. This chapter
2720 is split into sections, each of which documents one of the tasks
2721 provided from the top-level toolbar.
2724 <title>Monitor Flight</title>
2725 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
2727 Selecting this item brings up a dialog box listing all of the
2728 connected TeleDongle devices. When you choose one of these,
2729 AltosUI will create a window to display telemetry data as
2730 received by the selected TeleDongle device.
2735 <imagedata fileref="device-selection.png" width="3.1in"/>
2740 All telemetry data received are automatically recorded in
2741 suitable log files. The name of the files includes the current
2742 date and rocket serial and flight numbers.
2745 The radio frequency being monitored by the TeleDongle device is
2746 displayed at the top of the window. You can configure the
2747 frequency by clicking on the frequency box and selecting the desired
2748 frequency. AltosUI remembers the last frequency selected for each
2749 TeleDongle and selects that automatically the next time you use
2753 Below the TeleDongle frequency selector, the window contains a few
2754 significant pieces of information about the altimeter providing
2755 the telemetry data stream:
2759 <para>The configured call-sign</para>
2762 <para>The device serial number</para>
2765 <para>The flight number. Each altimeter remembers how many
2771 The rocket flight state. Each flight passes through several
2772 states including Pad, Boost, Fast, Coast, Drogue, Main and
2778 The Received Signal Strength Indicator value. This lets
2779 you know how strong a signal TeleDongle is receiving. At
2780 the default data rate, 38400 bps, in bench testing, the
2781 radio inside TeleDongle v0.2 operates down to about
2782 -106dBm, while the v3 radio works down to about -111dBm.
2783 Weaker signals, or an environment with radio noise may
2784 cause the data to not be received. The packet link uses
2785 error detection and correction techniques which prevent
2786 incorrect data from being reported.
2791 The age of the displayed data, in seconds since the last
2792 successfully received telemetry packet. In normal operation
2793 this will stay in the low single digits. If the number starts
2794 counting up, then you are no longer receiving data over the radio
2795 link from the flight computer.
2800 Finally, the largest portion of the window contains a set of
2801 tabs, each of which contain some information about the rocket.
2802 They're arranged in 'flight order' so that as the flight
2803 progresses, the selected tab automatically switches to display
2804 data relevant to the current state of the flight. You can select
2805 other tabs at any time. The final 'table' tab displays all of
2806 the raw telemetry values in one place in a spreadsheet-like format.
2809 <title>Launch Pad</title>
2813 <imagedata fileref="launch-pad.png" width="5.5in"/>
2818 The 'Launch Pad' tab shows information used to decide when the
2819 rocket is ready for flight. The first elements include red/green
2820 indicators, if any of these is red, you'll want to evaluate
2821 whether the rocket is ready to launch:
2824 <term>Battery Voltage</term>
2827 This indicates whether the Li-Po battery powering the
2828 flight computer has sufficient charge to last for
2829 the duration of the flight. A value of more than
2830 3.8V is required for a 'GO' status.
2835 <term>Apogee Igniter Voltage</term>
2838 This indicates whether the apogee
2839 igniter has continuity. If the igniter has a low
2840 resistance, then the voltage measured here will be close
2841 to the Li-Po battery voltage. A value greater than 3.2V is
2842 required for a 'GO' status.
2847 <term>Main Igniter Voltage</term>
2850 This indicates whether the main
2851 igniter has continuity. If the igniter has a low
2852 resistance, then the voltage measured here will be close
2853 to the Li-Po battery voltage. A value greater than 3.2V is
2854 required for a 'GO' status.
2859 <term>On-board Data Logging</term>
2862 This indicates whether there is
2863 space remaining on-board to store flight data for the
2864 upcoming flight. If you've downloaded data, but failed
2865 to erase flights, there may not be any space
2866 left. Most of our flight computers can store multiple
2867 flights, depending on the configured maximum flight log
2868 size. TeleMini v1.0 stores only a single flight, so it
2870 downloaded and erased after each flight to capture
2871 data. This only affects on-board flight logging; the
2872 altimeter will still transmit telemetry and fire
2873 ejection charges at the proper times even if the flight
2874 data storage is full.
2879 <term>GPS Locked</term>
2882 For a TeleMetrum or TeleMega device, this indicates whether the GPS receiver is
2883 currently able to compute position information. GPS requires
2884 at least 4 satellites to compute an accurate position.
2889 <term>GPS Ready</term>
2892 For a TeleMetrum or TeleMega device, this indicates whether GPS has reported at least
2893 10 consecutive positions without losing lock. This ensures
2894 that the GPS receiver has reliable reception from the
2902 The Launchpad tab also shows the computed launch pad position
2903 and altitude, averaging many reported positions to improve the
2904 accuracy of the fix.
2908 <title>Ascent</title>
2912 <imagedata fileref="ascent.png" width="5.5in"/>
2917 This tab is shown during Boost, Fast and Coast
2918 phases. The information displayed here helps monitor the
2919 rocket as it heads towards apogee.
2922 The height, speed, acceleration and tilt are shown along
2923 with the maximum values for each of them. This allows you to
2924 quickly answer the most commonly asked questions you'll hear
2928 The current latitude and longitude reported by the GPS are
2929 also shown. Note that under high acceleration, these values
2930 may not get updated as the GPS receiver loses position
2931 fix. Once the rocket starts coasting, the receiver should
2932 start reporting position again.
2935 Finally, the current igniter voltages are reported as in the
2936 Launch Pad tab. This can help diagnose deployment failures
2937 caused by wiring which comes loose under high acceleration.
2941 <title>Descent</title>
2945 <imagedata fileref="descent.png" width="5.5in"/>
2950 Once the rocket has reached apogee and (we hope) activated the
2951 apogee charge, attention switches to tracking the rocket on
2952 the way back to the ground, and for dual-deploy flights,
2953 waiting for the main charge to fire.
2956 To monitor whether the apogee charge operated correctly, the
2957 current descent rate is reported along with the current
2958 height. Good descent rates vary based on the choice of recovery
2959 components, but generally range from 15-30m/s on drogue and should
2960 be below 10m/s when under the main parachute in a dual-deploy flight.
2963 With GPS-equipped flight computers, you can locate the rocket in the
2964 sky using the elevation and bearing information to figure
2965 out where to look. Elevation is in degrees above the
2966 horizon. Bearing is reported in degrees relative to true
2967 north. Range can help figure out how big the rocket will
2968 appear. Ground Distance shows how far it is to a point
2969 directly under the rocket and can help figure out where the
2970 rocket is likely to land. Note that all of these values are
2971 relative to the pad location. If the elevation is near 90°,
2972 the rocket is over the pad, not over you.
2975 Finally, the igniter voltages are reported in this tab as
2976 well, both to monitor the main charge as well as to see what
2977 the status of the apogee charge is. Note that some commercial
2978 e-matches are designed to retain continuity even after being
2979 fired, and will continue to show as green or return from red to
2984 <title>Landed</title>
2988 <imagedata fileref="landed.png" width="5.5in"/>
2993 Once the rocket is on the ground, attention switches to
2994 recovery. While the radio signal is often lost once the
2995 rocket is on the ground, the last reported GPS position is
2996 generally within a short distance of the actual landing location.
2999 The last reported GPS position is reported both by
3000 latitude and longitude as well as a bearing and distance from
3001 the launch pad. The distance should give you a good idea of
3002 whether to walk or hitch a ride. Take the reported
3003 latitude and longitude and enter them into your hand-held GPS
3004 unit and have that compute a track to the landing location.
3007 Our flight computers will continue to transmit RDF
3008 tones after landing, allowing you to locate the rocket by
3009 following the radio signal if necessary. You may need to get
3010 away from the clutter of the flight line, or even get up on
3011 a hill (or your neighbor's RV roof) to receive the RDF signal.
3014 The maximum height, speed and acceleration reported
3015 during the flight are displayed for your admiring observers.
3016 The accuracy of these immediate values depends on the quality
3017 of your radio link and how many packets were received.
3018 Recovering the on-board data after flight may yield
3019 more precise results.
3022 To get more detailed information about the flight, you can
3023 click on the 'Graph Flight' button which will bring up a
3024 graph window for the current flight.
3028 <title>Table</title>
3032 <imagedata fileref="table.png" width="5.5in"/>
3037 The table view shows all of the data available from the
3038 flight computer. Probably the most useful data on
3039 this tab is the detailed GPS information, which includes
3040 horizontal dilution of precision information, and
3041 information about the signal being received from the satellites.
3045 <title>Site Map</title>
3049 <imagedata fileref="site-map.png" width="5.5in"/>
3054 When the TeleMetrum has a GPS fix, the Site Map tab will map
3055 the rocket's position to make it easier for you to locate the
3056 rocket, both while it is in the air, and when it has landed. The
3057 rocket's state is indicated by color: white for pad, red for
3058 boost, pink for fast, yellow for coast, light blue for drogue,
3059 dark blue for main, and black for landed.
3062 The map's default scale is approximately 3m (10ft) per pixel. The map
3063 can be dragged using the left mouse button. The map will attempt
3064 to keep the rocket roughly centered while data is being received.
3067 You can adjust the style of map and the zoom level with
3068 buttons on the right side of the map window. You can draw a
3069 line on the map by moving the mouse over the map with a
3070 button other than the left one pressed, or by pressing the
3071 left button while also holding down the shift key. The
3072 length of the line in real-world units will be shown at the
3076 Images are fetched automatically via the Google Maps Static API,
3077 and cached on disk for reuse. If map images cannot be downloaded,
3078 the rocket's path will be traced on a dark gray background
3082 You can pre-load images for your favorite launch sites
3083 before you leave home; check out the 'Preload Maps' section below.
3087 <title>Ignitor</title>
3091 <imagedata fileref="ignitor.png" width="5.5in"/>
3096 TeleMega includes four additional programmable pyro
3097 channels. The Ignitor tab shows whether each of them has
3098 continuity. If an ignitor has a low resistance, then the
3099 voltage measured here will be close to the pyro battery
3100 voltage. A value greater than 3.2V is required for a 'GO'
3106 <title>Save Flight Data</title>
3108 The altimeter records flight data to its internal flash memory.
3109 TeleMetrum data is recorded at a much higher rate than the telemetry
3110 system can handle, and is not subject to radio drop-outs. As
3111 such, it provides a more complete and precise record of the
3112 flight. The 'Save Flight Data' button allows you to read the
3113 flash memory and write it to disk.
3116 Clicking on the 'Save Flight Data' button brings up a list of
3117 connected flight computers and TeleDongle devices. If you select a
3118 flight computer, the flight data will be downloaded from that
3119 device directly. If you select a TeleDongle device, flight data
3120 will be downloaded from a flight computer over radio link via the
3121 specified TeleDongle. See the chapter on Controlling An Altimeter
3122 Over The Radio Link for more information.
3125 After the device has been selected, a dialog showing the
3126 flight data saved in the device will be shown allowing you to
3127 select which flights to download and which to delete. With
3128 version 0.9 or newer firmware, you must erase flights in order
3129 for the space they consume to be reused by another
3130 flight. This prevents accidentally losing flight data
3131 if you neglect to download data before flying again. Note that
3132 if there is no more space available in the device, then no
3133 data will be recorded during the next flight.
3136 The file name for each flight log is computed automatically
3137 from the recorded flight date, altimeter serial number and
3138 flight number information.
3142 <title>Replay Flight</title>
3144 Select this button and you are prompted to select a flight
3145 record file, either a .telem file recording telemetry data or a
3146 .eeprom file containing flight data saved from the altimeter
3150 Once a flight record is selected, the flight monitor interface
3151 is displayed and the flight is re-enacted in real time. Check
3152 the Monitor Flight chapter above to learn how this window operates.
3156 <title>Graph Data</title>
3158 Select this button and you are prompted to select a flight
3159 record file, either a .telem file recording telemetry data or a
3160 .eeprom file containing flight data saved from
3164 Note that telemetry files will generally produce poor graphs
3165 due to the lower sampling rate and missed telemetry packets.
3166 Use saved flight data in .eeprom files for graphing where possible.
3169 Once a flight record is selected, a window with multiple tabs is
3173 <title>Flight Graph</title>
3177 <imagedata fileref="graph.png" width="6in" scalefit="1"/>
3182 By default, the graph contains acceleration (blue),
3183 velocity (green) and altitude (red).
3186 The graph can be zoomed into a particular area by clicking and
3187 dragging down and to the right. Once zoomed, the graph can be
3188 reset by clicking and dragging up and to the left. Holding down
3189 control and clicking and dragging allows the graph to be panned.
3190 The right mouse button causes a pop-up menu to be displayed, giving
3191 you the option save or print the plot.
3195 <title>Configure Graph</title>
3199 <imagedata fileref="graph-configure.png" width="6in" scalefit="1"/>
3204 This selects which graph elements to show, and, at the
3205 very bottom, lets you switch between metric and
3210 <title>Flight Statistics</title>
3214 <imagedata fileref="graph-stats.png" width="6in" scalefit="1"/>
3219 Shows overall data computed from the flight.
3227 <imagedata fileref="graph-map.png" width="6in" scalefit="1"/>
3232 Shows a satellite image of the flight area overlaid
3233 with the path of the flight. The red concentric
3234 circles mark the launch pad, the black concentric
3235 circles mark the landing location.
3240 <title>Export Data</title>
3242 This tool takes the raw data files and makes them available for
3243 external analysis. When you select this button, you are prompted to
3244 select a flight data file, which can be either a .eeprom or .telem.
3245 The .eeprom files contain higher resolution and more continuous data,
3246 while .telem files contain receiver signal strength information.
3247 Next, a second dialog appears which is used to select
3248 where to write the resulting file. It has a selector to choose
3249 between CSV and KML file formats.
3252 <title>Comma Separated Value Format</title>
3254 This is a text file containing the data in a form suitable for
3255 import into a spreadsheet or other external data analysis
3256 tool. The first few lines of the file contain the version and
3257 configuration information from the altimeter, then
3258 there is a single header line which labels all of the
3259 fields. All of these lines start with a '#' character which
3260 many tools can be configured to skip over.
3263 The remaining lines of the file contain the data, with each
3264 field separated by a comma and at least one space. All of
3265 the sensor values are converted to standard units, with the
3266 barometric data reported in both pressure, altitude and
3267 height above pad units.
3271 <title>Keyhole Markup Language (for Google Earth)</title>
3273 This is the format used by Google Earth to provide an overlay
3274 within that application. With this, you can use Google Earth to
3275 see the whole flight path in 3D.
3280 <title>Configure Altimeter</title>
3284 <imagedata fileref="configure-altimeter.png" width="3.6in" scalefit="1"/>
3289 Select this button and then select either an altimeter or
3290 TeleDongle Device from the list provided. Selecting a TeleDongle
3291 device will use the radio link to configure a remote altimeter.
3294 The first few lines of the dialog provide information about the
3295 connected device, including the product name,
3296 software version and hardware serial number. Below that are the
3297 individual configuration entries.
3300 At the bottom of the dialog, there are four buttons:
3307 This writes any changes to the
3308 configuration parameter block in flash memory. If you don't
3309 press this button, any changes you make will be lost.
3317 This resets the dialog to the most recently saved values,
3318 erasing any changes you have made.
3326 This reboots the device. Use this to
3327 switch from idle to pad mode by rebooting once the rocket is
3328 oriented for flight, or to confirm changes you think you saved
3337 This closes the dialog. Any unsaved changes will be
3344 The rest of the dialog contains the parameters to be configured.
3347 <title>Main Deploy Altitude</title>
3349 This sets the altitude (above the recorded pad altitude) at
3350 which the 'main' igniter will fire. The drop-down menu shows
3351 some common values, but you can edit the text directly and
3352 choose whatever you like. If the apogee charge fires below
3353 this altitude, then the main charge will fire two seconds
3354 after the apogee charge fires.
3358 <title>Apogee Delay</title>
3360 When flying redundant electronics, it's often important to
3361 ensure that multiple apogee charges don't fire at precisely
3362 the same time, as that can over pressurize the apogee deployment
3363 bay and cause a structural failure of the air-frame. The Apogee
3364 Delay parameter tells the flight computer to fire the apogee
3365 charge a certain number of seconds after apogee has been
3370 <title>Apogee Lockoug</title>
3372 Apogee lockout is the number of seconds after boost where
3373 the flight computer will not fire the apogee charge, even if
3374 the rocket appears to be at apogee. This is often called
3375 'Mach Delay', as it is intended to prevent a flight computer
3376 from unintentionally firing apogee charges due to the pressure
3377 spike that occurrs across a mach transition. Altus Metrum
3378 flight computers include a Kalman filter which is not fooled
3379 by this sharp pressure increase, and so this setting should
3380 be left at the default value of zero to disable it.
3384 <title>Frequency</title>
3386 This configures which of the frequencies to use for both
3387 telemetry and packet command mode. Note that if you set this
3388 value via packet command mode, the TeleDongle frequency will
3389 also be automatically reconfigured to match so that
3390 communication will continue afterwards.
3394 <title>RF Calibration</title>
3396 The radios in every Altus Metrum device are calibrated at the
3397 factory to ensure that they transmit and receive on the
3398 specified frequency. If you need to you can adjust the calibration
3399 by changing this value. Do not do this without understanding what
3400 the value means, read the appendix on calibration and/or the source
3401 code for more information. To change a TeleDongle's calibration,
3402 you must reprogram the unit completely.
3406 <title>Telemetry/RDF/APRS Enable</title>
3408 Enables the radio for transmission during flight. When
3409 disabled, the radio will not transmit anything during flight
3414 <title>Telemetry baud rate</title>
3416 This sets the modulation bit rate for data transmission for
3417 both telemetry and packet link mode. Lower bit
3418 rates will increase range while reducing the amount of data
3419 that can be sent and increasing battery consumption. All
3420 telemetry is done using a rate 1/2 constraint 4 convolution
3421 code, so the actual data transmission rate is 1/2 of the
3422 modulation bit rate specified here.
3426 <title>APRS Interval</title>
3428 How often to transmit GPS information via APRS (in
3429 seconds). When set to zero, APRS transmission is
3430 disabled. This option is available on TeleMetrum v2 and
3431 TeleMega boards. TeleMetrum v1 boards cannot transmit APRS
3432 packets. Note that a single APRS packet takes nearly a full
3433 second to transmit, so enabling this option will prevent
3434 sending any other telemetry during that time.
3438 <title>APRS SSID</title>
3440 Which SSID to report in APRS packets. By default, this is
3441 set to the last digit of the serial number, but can be
3442 configured to any value from 0 to 9.
3446 <title>Callsign</title>
3448 This sets the call sign included in each telemetry packet. Set this
3449 as needed to conform to your local radio regulations.
3453 <title>Maximum Flight Log Size</title>
3455 This sets the space (in kilobytes) allocated for each flight
3456 log. The available space will be divided into chunks of this
3457 size. A smaller value will allow more flights to be stored,
3458 a larger value will record data from longer flights.
3462 <title>Ignitor Firing Mode</title>
3464 This configuration parameter allows the two standard ignitor
3465 channels (Apogee and Main) to be used in different
3470 <term>Dual Deploy</term>
3473 This is the usual mode of operation; the
3474 'apogee' channel is fired at apogee and the 'main'
3475 channel at the height above ground specified by the
3476 'Main Deploy Altitude' during descent.
3481 <term>Redundant Apogee</term>
3484 This fires both channels at
3485 apogee, the 'apogee' channel first followed after a two second
3486 delay by the 'main' channel.
3491 <term>Redundant Main</term>
3494 This fires both channels at the
3495 height above ground specified by the Main Deploy
3496 Altitude setting during descent. The 'apogee'
3497 channel is fired first, followed after a two second
3498 delay by the 'main' channel.
3505 <title>Pad Orientation</title>
3507 Because they include accelerometers, TeleMetrum,
3508 TeleMega and EasyMega are sensitive to the orientation of the board. By
3509 default, they expect the antenna end to point forward. This
3510 parameter allows that default to be changed, permitting the
3511 board to be mounted with the antenna pointing aft instead.
3515 <term>Antenna Up</term>
3518 In this mode, the antenna end of the
3519 flight computer must point forward, in line with the
3520 expected flight path.
3525 <term>Antenna Down</term>
3528 In this mode, the antenna end of the
3529 flight computer must point aft, in line with the
3530 expected flight path.
3537 <title>Beeper Frequency</title>
3539 The beeper on all Altus Metrum flight computers works best
3540 at 4000Hz, however if you have more than one flight computer
3541 in a single airframe, having all of them sound at the same
3542 frequency can be confusing. This parameter lets you adjust
3543 the base beeper frequency value.
3547 <title>Configure Pyro Channels</title>
3551 <imagedata fileref="configure-pyro.png" width="6in" scalefit="1"/>
3556 This opens a separate window to configure the additional
3557 pyro channels available on TeleMega and EasyMega. One column is
3558 presented for each channel. Each row represents a single
3559 parameter, if enabled the parameter must meet the specified
3560 test for the pyro channel to be fired. See the Pyro Channels
3561 section in the System Operation chapter above for a
3562 description of these parameters.
3565 Select conditions and set the related value; the pyro
3566 channel will be activated when <emphasis>all</emphasis> of the
3567 conditions are met. Each pyro channel has a separate set of
3568 configuration values, so you can use different values for
3569 the same condition with different channels.
3572 At the bottom of the window, the 'Pyro Firing Time'
3573 configuration sets the length of time (in seconds) which
3574 each of these pyro channels will fire for.
3577 Once you have selected the appropriate configuration for all
3578 of the necessary pyro channels, you can save the pyro
3579 configuration along with the rest of the flight computer
3580 configuration by pressing the 'Save' button in the main
3581 Configure Flight Computer window.
3586 <title>Configure AltosUI</title>
3590 <imagedata fileref="configure-altosui.png" width="2.4in" scalefit="1"/>
3595 This button presents a dialog so that you can configure the AltosUI global settings.
3598 <title>Voice Settings</title>
3600 AltosUI provides voice announcements during flight so that you
3601 can keep your eyes on the sky and still get information about
3602 the current flight status. However, sometimes you don't want
3609 <para>Turns all voice announcements on and off</para>
3613 <term>Test Voice</term>
3616 Plays a short message allowing you to verify
3617 that the audio system is working and the volume settings
3625 <title>Log Directory</title>
3627 AltosUI logs all telemetry data and saves all TeleMetrum flash
3628 data to this directory. This directory is also used as the
3629 staring point when selecting data files for display or export.
3632 Click on the directory name to bring up a directory choosing
3633 dialog, select a new directory and click 'Select Directory' to
3634 change where AltosUI reads and writes data files.
3638 <title>Callsign</title>
3640 This value is transmitted in each command packet sent from
3641 TeleDongle and received from an altimeter. It is not used in
3642 telemetry mode, as the callsign configured in the altimeter board
3643 is included in all telemetry packets. Configure this
3644 with the AltosUI operators call sign as needed to comply with
3645 your local radio regulations.
3648 Note that to successfully command a flight computer over the radio
3649 (to configure the altimeter, monitor idle, or fire pyro charges),
3650 the callsign configured here must exactly match the callsign
3651 configured in the flight computer. This matching is case
3656 <title>Imperial Units</title>
3658 This switches between metric units (meters) and imperial
3659 units (feet and miles). This affects the display of values
3660 use during flight monitoring, configuration, data graphing
3661 and all of the voice announcements. It does not change the
3662 units used when exporting to CSV files, those are always
3663 produced in metric units.
3667 <title>Font Size</title>
3669 Selects the set of fonts used in the flight monitor
3670 window. Choose between the small, medium and large sets.
3674 <title>Serial Debug</title>
3676 This causes all communication with a connected device to be
3677 dumped to the console from which AltosUI was started. If
3678 you've started it from an icon or menu entry, the output
3679 will simply be discarded. This mode can be useful to debug
3680 various serial communication issues.
3684 <title>Manage Frequencies</title>
3686 This brings up a dialog where you can configure the set of
3687 frequencies shown in the various frequency menus. You can
3688 add as many as you like, or even reconfigure the default
3689 set. Changing this list does not affect the frequency
3690 settings of any devices, it only changes the set of
3691 frequencies shown in the menus.
3696 <title>Configure Groundstation</title>
3700 <imagedata fileref="configure-groundstation.png" width="3.1in" scalefit="1"/>
3705 Select this button and then select a TeleDongle or TeleBT Device from the list provided.
3708 The first few lines of the dialog provide information about the
3709 connected device, including the product name,
3710 software version and hardware serial number. Below that are the
3711 individual configuration entries.
3714 Note that TeleDongle and TeleBT don't save any configuration
3715 data, the settings here are recorded on the local machine in
3716 the Java preferences database. Moving the device to
3717 another machine, or using a different user account on the same
3718 machine will cause settings made here to have no effect.
3721 At the bottom of the dialog, there are three buttons:
3728 This writes any changes to the
3729 local Java preferences file. If you don't
3730 press this button, any changes you make will be lost.
3738 This resets the dialog to the most recently saved values,
3739 erasing any changes you have made.
3747 This closes the dialog. Any unsaved changes will be
3754 The rest of the dialog contains the parameters to be configured.
3757 <title>Frequency</title>
3759 This configures the frequency to use for both telemetry and
3760 packet command mode. Set this before starting any operation
3761 involving packet command mode so that it will use the right
3762 frequency. Telemetry monitoring mode also provides a menu to
3763 change the frequency, and that menu also sets the same Java
3764 preference value used here.
3768 <title>RF Calibration</title>
3770 The radios in every Altus Metrum device are calibrated at the
3771 factory to ensure that they transmit and receive on the
3772 specified frequency. To change a TeleDongle or TeleBT's calibration,
3773 you must reprogram the unit completely, so this entry simply
3774 shows the current value and doesn't allow any changes.
3778 <title>Telemetry Rate</title>
3780 This lets you match the telemetry and packet link rate from
3781 the transmitter. If they don't match, the device won't
3787 <title>Flash Image</title>
3789 This reprograms Altus Metrum devices with new
3790 firmware. TeleMetrum v1.x, TeleDongle v0.2, TeleMini and
3791 TeleBT are all reprogrammed by using another similar unit as a
3792 programming dongle (pair programming). TeleMega, EasyMega,
3793 TeleMetrum v2, EasyMini and TeleDongle v3 are all programmed
3794 directly over their USB ports (self programming). Please read
3795 the directions for flashing devices in the Updating Device
3796 Firmware chapter below.
3800 <title>Fire Igniter</title>
3804 <imagedata fileref="fire-igniter.png" width="1.2in" scalefit="1"/>
3809 This activates the igniter circuits in the flight computer to help
3810 test recovery systems deployment. Because this command can operate
3811 over the Packet Command Link, you can prepare the rocket as
3812 for flight and then test the recovery system without needing
3813 to snake wires inside the air-frame.
3816 Selecting the 'Fire Igniter' button brings up the usual device
3817 selection dialog. Pick the desired device. This brings up another
3818 window which shows the current continuity test status for all
3819 of the pyro channels.
3822 Next, select the desired igniter to fire. This will enable the
3826 Select the 'Arm' button. This enables the 'Fire' button. The
3827 word 'Arm' is replaced by a countdown timer indicating that
3828 you have 10 seconds to press the 'Fire' button or the system
3829 will deactivate, at which point you start over again at
3830 selecting the desired igniter.
3834 <title>Scan Channels</title>
3838 <imagedata fileref="scan-channels.png" width="3.2in" scalefit="1"/>
3843 This listens for telemetry packets on all of the configured
3844 frequencies, displaying information about each device it
3845 receives a packet from. You can select which of the baud rates
3846 and telemetry formats should be tried; by default, it only listens
3847 at 38400 baud with the standard telemetry format used in v1.0 and later
3852 <title>Load Maps</title>
3856 <imagedata fileref="load-maps.png" width="5.2in" scalefit="1"/>
3861 Before heading out to a new launch site, you can use this to
3862 load satellite images in case you don't have internet
3863 connectivity at the site.
3866 There's a drop-down menu of launch sites we know about; if
3867 your favorites aren't there, please let us know the lat/lon
3868 and name of the site. The contents of this list are actually
3869 downloaded from our server at run-time, so as new sites are sent
3870 in, they'll get automatically added to this list.
3871 If the launch site isn't in the list, you can manually enter the lat/lon values
3874 There are four different kinds of maps you can view; you can
3875 select which to download by selecting as many as you like from
3876 the available types:
3882 A combination of satellite imagery and road data. This
3883 is the default view.
3888 <term>Satellite</term>
3891 Just the satellite imagery without any annotation.
3896 <term>Roadmap</term>
3899 Roads, political boundaries and a few geographic features.
3904 <term>Terrain</term>
3907 Contour intervals and shading that show hills and
3915 You can specify the range of zoom levels to download; smaller
3916 numbers show more area with less resolution. The default
3917 level, 0, shows about 3m/pixel. One zoom level change
3918 doubles or halves that number. Larger zoom levels show more
3919 detail, smaller zoom levels less.
3922 The Map Radius value sets how large an area around the center
3923 point to download. Select a value large enough to cover any
3924 plausible flight from that site. Be aware that loading a large
3925 area with a high maximum zoom level can attempt to download a
3926 lot of data. Loading hybrid maps with a 10km radius at a
3927 minimum zoom of -2 and a maximum zoom of 2 consumes about
3928 120MB of space. Terrain and road maps consume about 1/10 as
3929 much space as satellite or hybrid maps.
3932 Clicking the 'Load Map' button will fetch images from Google
3933 Maps; note that Google limits how many images you can fetch at
3934 once, so if you load more than one launch site, you may get
3935 some gray areas in the map which indicate that Google is tired
3936 of sending data to you. Try again later.
3940 <title>Monitor Idle</title>
3944 <imagedata fileref="monitor-idle.png" width="5.2in" scalefit="1"/>
3949 This brings up a dialog similar to the Monitor Flight UI,
3950 except it works with the altimeter in “idle” mode by sending
3951 query commands to discover the current state rather than
3952 listening for telemetry packets. Because this uses command
3953 mode, it needs to have the TeleDongle and flight computer
3954 callsigns match exactly. If you can receive telemetry, but
3955 cannot manage to run Monitor Idle, then it's very likely that
3956 your callsigns are different in some way.
3959 You can change the frequency and callsign used to communicate
3960 with the flight computer; they must both match the
3961 configuration in the flight computer exactly.
3966 <title>AltosDroid</title>
3968 AltosDroid provides the same flight monitoring capabilities as
3969 AltosUI, but runs on Android devices. AltosDroid is designed to connect
3970 to a TeleBT receiver over Bluetooth™ and (on Android devices supporting
3971 USB On-the-go) TeleDongle and TeleBT devices over USB. AltosDroid monitors
3972 telemetry data, logging it to internal storage in the Android
3973 device, and presents that data in a UI similar to the 'Monitor
3974 Flight' window in AltosUI.
3977 This manual will explain how to configure AltosDroid, connect to
3978 TeleBT or TeleDongle, operate the flight monitoring interface
3979 and describe what the displayed data means.
3982 <title>Installing AltosDroid</title>
3984 AltosDroid is available from the Google Play store. To install
3985 it on your Android device, open the Google Play Store
3986 application and search for “altosdroid”. Make sure you don't
3987 have a space between “altos” and “droid” or you probably won't
3988 find what you want. That should bring you to the right page
3989 from which you can download and install the application.
3993 <title>Connecting to TeleBT over Bluetooth™</title>
3995 Press the Android 'Menu' button or soft-key to see the
3996 configuration options available. Select the 'Connect a device'
3997 option and then the 'Scan for devices' entry at the bottom to
3998 look for your TeleBT device. Select your device, and when it
3999 asks for the code, enter '1234'.
4002 Subsequent connections will not require you to enter that
4003 code, and your 'paired' device will appear in the list without
4008 <title>Connecting to TeleDongle or TeleBT over USB</title>
4010 Get a special USB On-the-go adapter cable. These cables have a USB
4011 micro-B male connector on one end and a standard A female
4012 connector on the other end. Plug in your TeleDongle or TeleBT
4013 device to the adapter cable and the adapter cable into your
4014 phone and AltosDroid should automatically start up. If it
4015 doesn't, the most likely reason is that your Android device
4016 doesn't support USB On-the-go.
4020 <title>Configuring AltosDroid</title>
4022 There are several configuration and operation parameters
4023 available in the AltosDroid menu.
4026 <title>Select radio frequency</title>
4028 This selects which frequency to listen on by bringing up a
4029 menu of pre-set radio frequencies. Pick the one which matches
4034 <title>Select data rate</title>
4036 Altus Metrum transmitters can be configured to operate at
4037 lower data rates to improve transmission range. If you have
4038 configured your device to do this, this menu item allows you
4039 to change the receiver to match.
4043 <title>Change units</title>
4045 This toggles between metric and imperial units.
4049 <title>Load maps</title>
4051 Brings up a dialog allowing you to download offline map
4052 tiles so that you can have maps available even if you have
4053 no network connectivity at the launch site.
4057 <title>Map type</title>
4059 Displays a menu of map types and lets you select one. Hybrid
4060 maps include satellite images with a roadmap
4061 overlaid. Satellite maps dispense with the roadmap
4062 overlay. Roadmap shows just the roads. Terrain includes
4063 roads along with shadows indicating changes in elevation,
4064 and other geographical features.
4068 <title>Toggle Online/Offline maps</title>
4070 Switches between online and offline maps. Online maps will
4071 show a 'move to current position' icon in the upper right
4072 corner, while offline maps will have copyright information
4073 all over the map. Otherwise, they're pretty similar.
4077 <title>Select Tracker</title>
4079 Switches the information displays to show data for a
4080 different transmitting device. The map will always show all
4081 of the devices in view. Trackers are shown and selected by
4082 serial number, so make sure you note the serial number of
4083 devices in each airframe.
4087 <title>Delete Track</title>
4089 Deletes all information about a transmitting device.
4094 <title>AltosDroid Flight Monitoring</title>
4096 AltosDroid is designed to mimic the AltosUI flight monitoring
4097 display, providing separate tabs for each stage of your rocket
4098 flight along with a tab containing a map of the local area
4099 with icons marking the current location of the altimeter and
4105 The 'Pad' tab shows information used to decide when the
4106 rocket is ready for flight. The first elements include red/green
4107 indicators, if any of these is red, you'll want to evaluate
4108 whether the rocket is ready to launch.
4111 When the pad tab is selected, the voice responses will
4112 include status changes to the igniters and GPS reception,
4113 letting you know if the rocket is still ready for launch.
4117 <term>Battery</term>
4120 This indicates whether the Li-Po battery
4121 powering the transmitter has sufficient charge to last for
4122 the duration of the flight. A value of more than
4123 3.8V is required for a 'GO' status.
4128 <term>Receiver Battery</term>
4131 This indicates whether the Li-Po battery
4132 powering the TeleBT has sufficient charge to last for
4133 the duration of the flight. A value of more than
4134 3.8V is required for a 'GO' status.
4139 <term>Data Logging</term>
4142 This indicates whether there is space remaining
4143 on-board to store flight data for the upcoming
4144 flight. If you've downloaded data, but failed to
4145 erase flights, there may not be any space
4146 left. TeleMetrum and TeleMega can store multiple
4147 flights, depending on the configured maximum flight
4148 log size. TeleGPS logs data continuously. TeleMini
4149 stores only a single flight, so it will need to be
4150 downloaded and erased after each flight to capture
4151 data. This only affects on-board flight logging; the
4152 altimeter will still transmit telemetry and fire
4153 ejection charges at the proper times.
4158 <term>GPS Locked</term>
4161 For a TeleMetrum or TeleMega device, this indicates whether the GPS receiver is
4162 currently able to compute position information. GPS requires
4163 at least 4 satellites to compute an accurate position.
4168 <term>GPS Ready</term>
4171 For a TeleMetrum or TeleMega device, this indicates whether GPS has reported at least
4172 10 consecutive positions without losing lock. This ensures
4173 that the GPS receiver has reliable reception from the
4179 <term>Apogee Igniter</term>
4182 This indicates whether the apogee
4183 igniter has continuity. If the igniter has a low
4184 resistance, then the voltage measured here will be close
4185 to the Li-Po battery voltage. A value greater than 3.2V is
4186 required for a 'GO' status.
4191 <term>Main Igniter</term>
4194 This indicates whether the main
4195 igniter has continuity. If the igniter has a low
4196 resistance, then the voltage measured here will be close
4197 to the Li-Po battery voltage. A value greater than 3.2V is
4198 required for a 'GO' status.
4203 <term>Igniter A-D</term>
4206 This indicates whether the indicated additional pyro
4207 channel igniter has continuity. If the igniter has a
4208 low resistance, then the voltage measured here will
4209 be close to the Li-Po battery voltage. A value
4210 greater than 3.2V is required for a 'GO' status.
4216 The Pad tab also shows the location of the Android device.
4220 <title>Flight</title>
4222 The 'Flight' tab shows information used to evaluate and spot
4223 a rocket while in flight. It displays speed and height data
4224 to monitor the health of the rocket, along with elevation,
4225 range and bearing to help locate the rocket in the sky.
4228 While the Flight tab is displayed, the voice announcements
4229 will include current speed, height, elevation and bearing
4237 Shows current vertical speed. During descent, the
4238 speed values are averaged over a fairly long time to
4239 try and make them steadier.
4247 Shows the current height above the launch pad.
4252 <term>Max Speed</term>
4255 Shows the maximum vertical speed seen during the flight.
4260 <term>Max Height</term>
4263 Shows the maximum height above launch pad.
4268 <term>Elevation</term>
4271 This is the angle above the horizon from the android
4272 devices current position.
4280 The total distance from the android device to the
4281 rocket, including both ground distance and
4282 difference in altitude. Use this to gauge how large
4283 the rocket is likely to appear in the sky.
4288 <term>Bearing</term>
4291 This is the aziumuth from true north for the rocket
4292 from the android device. Use this in combination
4293 with the Elevation value to help locate the rocket
4294 in the sky, or at least to help point the antenna in
4295 the general direction. This is provided in both
4296 degrees and a compass point (like West South
4297 West). You'll want to know which direction is true
4298 north before launching your rocket.
4303 <term>Ground Distance</term>
4306 This shows the distance across the ground to the
4307 lat/lon where the rocket is located. Use this to
4308 estimate what is currently under the rocket.
4313 <term>Latitude/Longitude</term>
4316 Displays the last known location of the rocket.
4321 <term>Apogee Igniter</term>
4324 This indicates whether the apogee
4325 igniter has continuity. If the igniter has a low
4326 resistance, then the voltage measured here will be close
4327 to the Li-Po battery voltage. A value greater than 3.2V is
4328 required for a 'GO' status.
4333 <term>Main Igniter</term>
4336 This indicates whether the main
4337 igniter has continuity. If the igniter has a low
4338 resistance, then the voltage measured here will be close
4339 to the Li-Po battery voltage. A value greater than 3.2V is
4340 required for a 'GO' status.
4347 <title>Recover</title>
4349 The 'Recover' tab shows information used while recovering the
4350 rocket on the ground after flight.
4353 While the Recover tab is displayed, the voice announcements
4354 will include distance along with either bearing or
4355 direction, depending on whether you are moving.
4359 <term>Bearing</term>
4362 This is the aziumuth from true north for the rocket
4363 from the android device. Use this in combination
4364 with the Elevation value to help locate the rocket
4365 in the sky, or at least to help point the antenna in
4366 the general direction. This is provided in both
4367 degrees and a compass point (like West South
4368 West). You'll want to know which direction is true
4369 north before launching your rocket.
4374 <term>Direction</term>
4377 When you are in motion, this provides the angle from
4378 your current direction of motion towards the rocket.
4383 <term>Distance</term>
4386 Distance over the ground to the rocket.
4391 <term>Tar Lat/Tar Lon</term>
4394 Displays the last known location of the rocket.
4399 <term>My Lat/My Lon</term>
4402 Displays the location of the Android device.
4407 <term>Max Height</term>
4410 Shows the maximum height above launch pad.
4415 <term>Max Speed</term>
4418 Shows the maximum vertical speed seen during the flight.
4423 <term>Max Accel</term>
4426 Shows the maximum vertical acceleration seen during the flight.
4435 The 'Map' tab shows a map of the area around the rocket
4436 being tracked along with information needed to recover it.
4439 On the map itself, icons showing the location of the android
4440 device along with the last known location of each tracker. A
4441 blue line is drawn from the android device location to the
4442 currently selected tracker.
4445 Below the map, the distance and either bearing or direction
4446 along with the lat/lon of the target and the android device
4450 The Map tab provides the same voice announcements as the
4456 <title>Downloading Flight Logs</title>
4458 AltosDroid always saves every bit of telemetry data it
4459 receives. To download that to a computer for use with AltosUI,
4460 remove the SD card from your Android device, or connect your
4461 device to your computer's USB port and browse the files on
4462 that device. You will find '.telem' files in the TeleMetrum
4463 directory that will work with AltosUI directly.
4468 <title>Using Altus Metrum Products</title>
4470 <title>Being Legal</title>
4472 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
4473 other authorization to legally operate the radio transmitters that are part
4478 <title>In the Rocket</title>
4480 In the rocket itself, you just need a flight computer and
4481 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
4482 850mAh battery weighs less than a 9V alkaline battery, and will
4483 run a TeleMetrum, TeleMega or EasyMega for hours.
4484 A 110mAh battery weighs less than a triple A battery and is a good
4485 choice for use with TeleMini or EasyMini.
4488 By default, we ship TeleMini, TeleMetrum and TeleMega flight computers with a simple wire antenna.
4489 If your electronics bay or the air-frame it resides within is made
4490 of carbon fiber, which is opaque to RF signals, you may prefer to
4491 install an SMA connector so that you can run a coaxial cable to an
4492 antenna mounted elsewhere in the rocket. However, note that the
4493 GPS antenna is fixed on all current products, so you really want
4494 to install the flight computer in a bay made of RF-transparent
4495 materials if at all possible.
4499 <title>On the Ground</title>
4501 To receive the data stream from the rocket, you need an antenna and short
4502 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. If possible, use an SMA to BNC
4503 adapter instead of feedline between the antenna feedpoint and
4504 TeleDongle, as this will give you the best performance. The
4505 TeleDongle in turn plugs directly into the USB port on a notebook
4506 computer. Because TeleDongle looks like a simple serial port, your computer
4507 does not require special device drivers... just plug it in.
4510 The GUI tool, AltosUI, is written in Java and runs across
4511 Linux, Mac OS and Windows. There's also a suite of C tools
4512 for Linux which can perform most of the same tasks.
4515 Alternatively, a TeleBT attached with an SMA to BNC adapter at the
4516 feed point of a hand-held yagi used in conjunction with an Android
4517 device running AltosDroid makes an outstanding ground station.
4520 After the flight, you can use the radio link to extract the more detailed data
4521 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
4522 TeleMetrum board directly. Pulling out the data without having to open up
4523 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
4524 battery, so you'll want one of those anyway... the same cable used by lots
4525 of digital cameras and other modern electronic stuff will work fine.
4528 If your rocket lands out of sight, you may enjoy having a hand-held
4529 GPS receiver, so that you can put in a way-point for the last
4530 reported rocket position before touch-down. This makes looking for
4531 your rocket a lot like Geo-Caching... just go to the way-point and
4532 look around starting from there. AltosDroid on an Android device
4533 with GPS receiver works great for this, too!
4536 You may also enjoy having a ham radio “HT” that covers the 70cm band... you
4537 can use that with your antenna to direction-find the rocket on the ground
4538 the same way you can use a Walston or Beeline tracker. This can be handy
4539 if the rocket is hiding in sage brush or a tree, or if the last GPS position
4540 doesn't get you close enough because the rocket dropped into a canyon, or
4541 the wind is blowing it across a dry lake bed, or something like that... Keith
4542 currently uses a Yaesu FT1D, Bdale has a Yaesu VX-7R, which
4543 is a nicer radio in most ways but doesn't support APRS.
4546 So, to recap, on the ground the hardware you'll need includes:
4547 <orderedlist inheritnum='inherit' numeration='arabic'>
4550 an antenna and feed-line or adapter
4565 optionally, a hand-held GPS receiver
4570 optionally, an HT or receiver covering 435 MHz
4576 The best hand-held commercial directional antennas we've found for radio
4577 direction finding rockets are from
4578 <ulink url="http://www.arrowantennas.com/" >
4581 The 440-3 and 440-5 are both good choices for finding a
4582 TeleMetrum- or TeleMini- equipped rocket when used with a suitable
4583 70cm HT. TeleDongle and an SMA to BNC adapter fit perfectly
4584 between the driven element and reflector of Arrow antennas.
4588 <title>Data Analysis</title>
4590 Our software makes it easy to log the data from each flight, both the
4591 telemetry received during the flight itself, and the more
4592 complete data log recorded in the flash memory on the altimeter
4593 board. Once this data is on your computer, our post-flight tools make it
4594 easy to quickly get to the numbers everyone wants, like apogee altitude,
4595 max acceleration, and max velocity. You can also generate and view a
4596 standard set of plots showing the altitude, acceleration, and
4597 velocity of the rocket during flight. And you can even export a TeleMetrum data file
4598 usable with Google Maps and Google Earth for visualizing the flight path
4599 in two or three dimensions!
4602 Our ultimate goal is to emit a set of files for each flight that can be
4603 published as a web page per flight, or just viewed on your local disk with
4608 <title>Future Plans</title>
4610 We have designed and prototyped several “companion boards” that
4611 can attach to the companion connector on TeleMetrum,
4612 TeleMega and EasyMega
4613 flight computers to collect more data, provide more pyro channels,
4614 and so forth. We do not yet know if or when any of these boards
4615 will be produced in enough quantity to sell. If you have specific
4616 interests for data collection or control of events in your rockets
4617 beyond the capabilities of our existing productions, please let
4621 Because all of our work is open, both the hardware designs and the
4622 software, if you have some great idea for an addition to the current
4623 Altus Metrum family, feel free to dive in and help! Or let us know
4624 what you'd like to see that we aren't already working on, and maybe
4625 we'll get excited about it too...
4629 <ulink url="http://altusmetrum.org/">web site</ulink> for more news
4630 and information as our family of products evolves!
4635 <title>Altimeter Installation Recommendations</title>
4637 Building high-power rockets that fly safely is hard enough. Mix
4638 in some sophisticated electronics and a bunch of radio energy
4639 and some creativity and/or compromise may be required. This chapter
4640 contains some suggestions about how to install Altus Metrum
4641 products into a rocket air-frame, including how to safely and
4642 reliably mix a variety of electronics into the same air-frame.
4645 <title>Mounting the Altimeter</title>
4647 The first consideration is to ensure that the altimeter is
4648 securely fastened to the air-frame. For most of our products, we
4649 prefer nylon standoffs and nylon screws; they're good to at least 50G
4650 and cannot cause any electrical issues on the board. Metal screws
4651 and standoffs are fine, too, just be careful to avoid electrical
4652 shorts! For TeleMini v1.0, we usually cut small pieces of 1/16 inch
4654 under the screw holes, and then take 2x56 nylon screws and
4655 screw them through the TeleMini mounting holes, through the
4656 balsa and into the underlying material.
4658 <orderedlist inheritnum='inherit' numeration='arabic'>
4661 Make sure accelerometer-equipped products like TeleMetrum,
4662 TeleMega and EasyMega are aligned precisely along the axis of
4663 acceleration so that the accelerometer can accurately
4664 capture data during the flight.
4669 Watch for any metal touching components on the
4670 board. Shorting out connections on the bottom of the board
4671 can cause the altimeter to fail during flight.
4677 <title>Dealing with the Antenna</title>
4679 The antenna supplied is just a piece of solid, insulated,
4680 wire. If it gets damaged or broken, it can be easily
4681 replaced. It should be kept straight and not cut; bending or
4682 cutting it will change the resonant frequency and/or
4683 impedance, making it a less efficient radiator and thus
4684 reducing the range of the telemetry signal.
4687 Keeping metal away from the antenna will provide better range
4688 and a more even radiation pattern. In most rockets, it's not
4689 entirely possible to isolate the antenna from metal
4690 components; there are often bolts, all-thread and wires from other
4691 electronics to contend with. Just be aware that the more stuff
4692 like this around the antenna, the lower the range.
4695 Make sure the antenna is not inside a tube made or covered
4696 with conducting material. Carbon fiber is the most common
4697 culprit here -- CF is a good conductor and will effectively
4698 shield the antenna, dramatically reducing signal strength and
4699 range. Metallic flake paint is another effective shielding
4700 material which should be avoided around any antennas.
4703 If the ebay is large enough, it can be convenient to simply
4704 mount the altimeter at one end and stretch the antenna out
4705 inside. Taping the antenna to the sled can keep it straight
4706 under acceleration. If there are metal rods, keep the
4707 antenna as far away as possible.
4710 For a shorter ebay, it's quite practical to have the antenna
4711 run through a bulkhead and into an adjacent bay. Drill a small
4712 hole in the bulkhead, pass the antenna wire through it and
4713 then seal it up with glue or clay. We've also used acrylic
4714 tubing to create a cavity for the antenna wire. This works a
4715 bit better in that the antenna is known to stay straight and
4716 not get folded by recovery components in the bay. Angle the
4717 tubing towards the side wall of the rocket and it ends up
4718 consuming very little space.
4721 If you need to place the UHF antenna at a distance from the
4722 altimeter, you can replace the antenna with an edge-mounted
4723 SMA connector, and then run 50Ω coax from the board to the
4724 antenna. Building a remote antenna is beyond the scope of this
4729 <title>Preserving GPS Reception</title>
4731 The GPS antenna and receiver used in TeleMetrum and TeleMega is
4732 highly sensitive and normally have no trouble tracking enough
4733 satellites to provide accurate position information for
4734 recovering the rocket. However, there are many ways the GPS signal
4735 can end up attenuated, negatively affecting GPS performance.
4736 <orderedlist inheritnum='inherit' numeration='arabic'>
4739 Conductive tubing or coatings. Carbon fiber and metal
4740 tubing, or metallic paint will all dramatically attenuate the
4741 GPS signal. We've never heard of anyone successfully
4742 receiving GPS from inside these materials.
4747 Metal components near the GPS patch antenna. These will
4748 de-tune the patch antenna, changing the resonant frequency
4749 away from the L1 carrier and reduce the effectiveness of the
4750 antenna. You can place as much stuff as you like beneath the
4751 antenna as that's covered with a ground plane. But, keep
4752 wires and metal out from above the patch antenna.
4759 <title>Radio Frequency Interference</title>
4761 Any altimeter will generate RFI; the digital circuits use
4762 high-frequency clocks that spray radio interference across a
4763 wide band. Altus Metrum altimeters generate intentional radio
4764 signals as well, increasing the amount of RF energy around the board.
4767 Rocketry altimeters also use precise sensors measuring air
4768 pressure and acceleration. Tiny changes in voltage can cause
4769 these sensor readings to vary by a huge amount. When the
4770 sensors start mis-reporting data, the altimeter can either
4771 fire the igniters at the wrong time, or not fire them at all.
4774 Voltages are induced when radio frequency energy is
4775 transmitted from one circuit to another. Here are things that
4776 influence the induced voltage and current:
4781 Keep wires from different circuits apart. Moving circuits
4782 further apart will reduce RFI.
4787 Avoid parallel wires from different circuits. The longer two
4788 wires run parallel to one another, the larger the amount of
4789 transferred energy. Cross wires at right angles to reduce
4795 Twist wires from the same circuits. Two wires the same
4796 distance from the transmitter will get the same amount of
4797 induced energy which will then cancel out. Any time you have
4798 a wire pair running together, twist the pair together to
4799 even out distances and reduce RFI. For altimeters, this
4800 includes battery leads, switch hookups and igniter
4806 Avoid resonant lengths. Know what frequencies are present
4807 in the environment and avoid having wire lengths near a
4808 natural resonant length. Altus Metrum products transmit on the
4809 70cm amateur band, so you should avoid lengths that are a
4810 simple ratio of that length; essentially any multiple of ¼
4811 of the wavelength (17.5cm).
4817 <title>The Barometric Sensor</title>
4819 Altusmetrum altimeters measure altitude with a barometric
4820 sensor, essentially measuring the amount of air above the
4821 rocket to figure out how high it is. A large number of
4822 measurements are taken as the altimeter initializes itself to
4823 figure out the pad altitude. Subsequent measurements are then
4824 used to compute the height above the pad.
4827 To accurately measure atmospheric pressure, the ebay
4828 containing the altimeter must be vented outside the
4829 air-frame. The vent must be placed in a region of linear
4830 airflow, have smooth edges, and away from areas of increasing or
4831 decreasing pressure.
4834 All barometric sensors are quite sensitive to chemical damage from
4835 the products of APCP or BP combustion, so make sure the ebay is
4836 carefully sealed from any compartment which contains ejection
4841 <title>Ground Testing</title>
4843 The most important aspect of any installation is careful
4844 ground testing. Bringing an air-frame up to the LCO table which
4845 hasn't been ground tested can lead to delays or ejection
4846 charges firing on the pad, or, even worse, a recovery system
4850 Do a 'full systems' test that includes wiring up all igniters
4851 without any BP and turning on all of the electronics in flight
4852 mode. This will catch any mistakes in wiring and any residual
4853 RFI issues that might accidentally fire igniters at the wrong
4854 time. Let the air-frame sit for several minutes, checking for
4855 adequate telemetry signal strength and GPS lock. If any igniters
4856 fire unexpectedly, find and resolve the issue before loading any
4860 Ground test the ejection charges. Prepare the rocket for
4861 flight, loading ejection charges and igniters. Completely
4862 assemble the air-frame and then use the 'Fire Igniters'
4863 interface through a TeleDongle to command each charge to
4864 fire. Make sure the charge is sufficient to robustly separate
4865 the air-frame and deploy the recovery system.
4870 <title>Updating Device Firmware</title>
4872 TeleMega, TeleMetrum v2, EasyMega, EasyMini and TeleDongle v3
4873 are all programmed directly over their USB connectors (self
4874 programming). TeleMetrum v1, TeleMini and TeleDongle v0.2 are
4875 all programmed by using another device as a programmer (pair
4876 programming). It's important to recognize which kind of devices
4877 you have before trying to reprogram them.
4880 You may wish to begin by ensuring you have current firmware images.
4881 These are distributed as part of the AltOS software bundle that
4882 also includes the AltosUI ground station program. Newer ground
4883 station versions typically work fine with older firmware versions,
4884 so you don't need to update your devices just to try out new
4885 software features. You can always download the most recent
4886 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
4889 If you need to update the firmware on a TeleDongle v0.2, we recommend
4890 updating the altimeter first, before updating TeleDongle. However,
4891 note that TeleDongle rarely need to be updated. Any firmware version
4892 1.0.1 or later will work, version 1.2.1 may have improved receiver
4893 performance slightly.
4896 Self-programmable devices (TeleMega, TeleMetrum v2, EasyMega and EasyMini)
4897 are reprogrammed by connecting them to your computer over USB
4901 Updating TeleMega, TeleMetrum v2, EasyMega, EasyMini or
4902 TeleDongle v3 Firmware
4904 <orderedlist inheritnum='inherit' numeration='arabic'>
4907 Attach a battery if necessary and power switch to the target
4908 device. Power up the device.
4913 Using a Micro USB cable, connect the target device to your
4914 computer's USB socket.
4919 Run AltosUI, and select 'Flash Image' from the File menu.
4924 Select the target device in the Device Selection dialog.
4929 Select the image you want to flash to the device, which
4930 should have a name in the form
4931 <product>-v<product-version>-<software-version>.ihx, such
4932 as TeleMega-v1.0-1.3.0.ihx.
4937 Make sure the configuration parameters are reasonable
4938 looking. If the serial number and/or RF configuration
4939 values aren't right, you'll need to change them.
4944 Hit the 'OK' button and the software should proceed to flash
4945 the device with new firmware, showing a progress bar.
4950 Verify that the device is working by using the 'Configure
4951 Altimeter' or 'Configure Groundstation' item to check over
4957 <title>Recovering From Self-Flashing Failure</title>
4959 If the firmware loading fails, it can leave the device
4960 unable to boot. Not to worry, you can force the device to
4961 start the boot loader instead, which will let you try to
4962 flash the device again.
4965 On each device, connecting two pins from one of the exposed
4966 connectors will force the boot loader to start, even if the
4967 regular operating system has been corrupted in some way.
4971 <term>TeleMega</term>
4974 Connect pin 6 and pin 1 of the companion connector. Pin 1
4975 can be identified by the square pad around it, and then
4976 the pins could sequentially across the board. Be very
4977 careful to <emphasis>not</emphasis> short pin 8 to
4978 anything as that is connected directly to the battery. Pin
4979 7 carries 3.3V and the board will crash if that is
4980 connected to pin 1, but shouldn't damage the board.
4985 <term>EasyMega</term>
4988 Connect pin 6 and pin 1 of the companion connector. Pin 1
4989 can be identified by the square pad around it, and then
4990 the pins could sequentially across the board. Be very
4991 careful to <emphasis>not</emphasis> short pin 8 to
4992 anything as that is connected directly to the battery. Pin
4993 7 carries 3.3V and the board will crash if that is
4994 connected to pin 1, but shouldn't damage the board.
4999 <term>TeleMetrum v2</term>
5002 Connect pin 6 and pin 1 of the companion connector. Pin 1
5003 can be identified by the square pad around it, and then
5004 the pins could sequentially across the board. Be very
5005 careful to <emphasis>not</emphasis> short pin 8 to
5006 anything as that is connected directly to the battery. Pin
5007 7 carries 3.3V and the board will crash if that is
5008 connected to pin 1, but shouldn't damage the board.
5013 <term>EasyMini</term>
5016 Connect pin 6 and pin 1 of the debug connector, which is
5017 the six holes next to the beeper. Pin 1 can be identified
5018 by the square pad around it, and then the pins could
5019 sequentially across the board, making Pin 6 the one on the
5020 other end of the row.
5025 <term>TeleDongle v3</term>
5028 Connect pin 32 on the CPU to ground. Pin 32 is closest
5029 to the USB wires on the row of pins towards the center
5030 of the board. Ground is available on the capacitor
5031 next to it, on the end towards the USB wires.
5037 Once you've located the right pins:
5039 <orderedlist inheritnum='inherit' numeration='arabic'>
5042 Turn the altimeter power off.
5052 Connect the indicated terminals together with a short
5053 piece of wire. Take care not to accidentally connect
5064 Turn the board power on.
5069 The board should now be visible over USB as 'AltosFlash'
5070 and be ready to receive firmware.
5075 Once the board has been powered up, you can remove the
5083 <title>Pair Programming</title>
5085 The big concept to understand is that you have to use a
5086 TeleMetrum v1.0, TeleBT v1.0 or TeleDongle v0.2 as a
5087 programmer to update a pair programmed device. Due to limited
5088 memory resources in the cc1111, we don't support programming
5089 directly over USB for these devices.
5093 <title>Updating TeleMetrum v1.x Firmware</title>
5094 <orderedlist inheritnum='inherit' numeration='arabic'>
5097 Find the 'programming cable' that you got as part of the starter
5098 kit, that has a red 8-pin MicroMaTch connector on one end and a
5099 red 4-pin MicroMaTch connector on the other end.
5104 Take the 2 screws out of the TeleDongle v0.2 or TeleBT v1.0
5105 case to get access to the circuit board.
5110 Plug the 8-pin end of the programming cable to the
5111 matching connector on the TeleDongle v0.2 or TeleBT v1.0, and the 4-pin end to the
5112 matching connector on the TeleMetrum.
5113 Note that each MicroMaTch connector has an alignment pin that
5114 goes through a hole in the PC board when you have the cable
5120 Attach a battery to the TeleMetrum board.
5125 Plug the TeleDongle v0.2 or TeleBT v1.0 into your computer's USB port, and power
5131 Run AltosUI, and select 'Flash Image' from the File menu.
5136 Pick the TeleDongle v0.2 or TeleBT v1.0 device from the list, identifying it as the
5142 Select the image you want put on the TeleMetrum, which should have a
5143 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
5144 in the default directory, if not you may have to poke around
5145 your system to find it.
5150 Make sure the configuration parameters are reasonable
5151 looking. If the serial number and/or RF configuration
5152 values aren't right, you'll need to change them.
5157 Hit the 'OK' button and the software should proceed to flash
5158 the TeleMetrum with new firmware, showing a progress bar.
5163 Confirm that the TeleMetrum board seems to have updated OK, which you
5164 can do by plugging in to it over USB and using a terminal program
5165 to connect to the board and issue the 'v' command to check
5171 If something goes wrong, give it another try.
5177 <title>Updating TeleMini Firmware</title>
5178 <orderedlist inheritnum='inherit' numeration='arabic'>
5181 You'll need a special 'programming cable' to reprogram the
5182 TeleMini. You can make your own using an 8-pin MicroMaTch
5183 connector on one end and a set of four pins on the other.
5188 Take the 2 screws out of the TeleDongle v0.2 or TeleBT v1.0 case to get access
5189 to the circuit board.
5194 Plug the 8-pin end of the programming cable to the matching
5195 connector on the TeleDongle v0.2 or TeleBT v1.0, and the 4-pins into the holes
5196 in the TeleMini circuit board. Note that the MicroMaTch
5197 connector has an alignment pin that goes through a hole in
5198 the PC board when you have the cable oriented correctly, and
5199 that pin 1 on the TeleMini board is marked with a square pad
5200 while the other pins have round pads.
5205 Attach a battery to the TeleMini board.
5210 Plug the TeleDongle v0.2 or TeleBT v1.0 into your computer's USB port, and power
5216 Run AltosUI, and select 'Flash Image' from the File menu.
5221 Pick the TeleDongle v0.2 or TeleBT v1.0 device from the list, identifying it as the
5227 Select the image you want put on the TeleMini, which should have a
5228 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
5229 in the default directory, if not you may have to poke around
5230 your system to find it.
5235 Make sure the configuration parameters are reasonable
5236 looking. If the serial number and/or RF configuration
5237 values aren't right, you'll need to change them.
5242 Hit the 'OK' button and the software should proceed to flash
5243 the TeleMini with new firmware, showing a progress bar.
5248 Confirm that the TeleMini board seems to have updated OK, which you
5249 can do by configuring it over the radio link through the TeleDongle, or
5250 letting it come up in “flight” mode and listening for telemetry.
5255 If something goes wrong, give it another try.
5261 <title>Updating TeleDongle v0.2 Firmware</title>
5263 Updating TeleDongle v0.2 firmware is just like updating
5264 TeleMetrum v1.x or TeleMini
5265 firmware, but you use either a TeleMetrum v1.x, TeleDongle
5266 v0.2 or TeleBT v1.0 as the programmer.
5268 <orderedlist inheritnum='inherit' numeration='arabic'>
5271 Find the 'programming cable' that you got as part of the starter
5272 kit, that has a red 8-pin MicroMaTch connector on one end and a
5273 red 4-pin MicroMaTch connector on the other end.
5278 Find the USB cable that you got as part of the starter kit, and
5279 plug the “mini” end in to the mating connector on TeleMetrum
5280 v1.x, TeleDongle v0.2 or TeleBT v1.0.
5285 Take the 2 screws out of the TeleDongle v0.2 or TeleBT v1.0 case to get access
5286 to the circuit board.
5291 Plug the 8-pin end of the programming cable to the
5292 matching connector on the programmer, and the 4-pin end to the
5293 matching connector on the TeleDongle v0.2.
5294 Note that each MicroMaTch connector has an alignment pin that
5295 goes through a hole in the PC board when you have the cable
5301 Attach a battery to the TeleMetrum v1.x board if you're using one.
5306 Plug both the programmer and the TeleDongle into your computer's USB
5307 ports, and power up the programmer.
5312 Run AltosUI, and select 'Flash Image' from the File menu.
5317 Pick the programmer device from the list, identifying it as the
5323 Select the image you want put on the TeleDongle v0.2, which should have a
5324 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
5325 in the default directory, if not you may have to poke around
5326 your system to find it.
5331 Make sure the configuration parameters are reasonable
5332 looking. If the serial number and/or RF configuration
5333 values aren't right, you'll need to change them. The
5335 serial number is on the “bottom” of the circuit board, and can
5336 usually be read through the translucent blue plastic case without
5337 needing to remove the board from the case.
5342 Hit the 'OK' button and the software should proceed to flash
5343 the TeleDongle v0.2 with new firmware, showing a progress bar.
5348 Confirm that the TeleDongle v0.2 board seems to have updated OK, which you
5349 can do by plugging in to it over USB and using a terminal program
5350 to connect to the board and issue the 'v' command to check
5351 the version, etc. Once you're happy, remove the programming cable
5352 and put the cover back on the TeleDongle v0.2.
5357 If something goes wrong, give it another try.
5362 Be careful removing the programming cable from the locking 8-pin
5363 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
5364 screwdriver or knife blade to gently pry the locking ears out
5365 slightly to extract the connector. We used a locking connector on
5366 TeleMetrum to help ensure that the cabling to companion boards
5367 used in a rocket don't ever come loose accidentally in flight.
5372 <title>Hardware Specifications</title>
5375 TeleMega Specifications
5380 Recording altimeter for model rocketry.
5385 Supports dual deployment and four auxiliary pyro channels
5386 (a total of 6 events).
5391 70cm 40mW ham-band transceiver for telemetry down-link.
5396 Barometric pressure sensor good to 100k feet MSL.
5401 1-axis high-g accelerometer for motor characterization, capable of
5407 9-axis IMU including integrated 3-axis accelerometer,
5408 3-axis gyroscope and 3-axis magnetometer.
5413 On-board, integrated uBlox Max 7 GPS receiver with 5Hz update rate capability.
5418 On-board 8 Megabyte non-volatile memory for flight data storage.
5423 USB interface for battery charging, configuration, and data recovery.
5428 Fully integrated support for Li-Po rechargeable batteries.
5433 Can use either main system Li-Po or optional separate pyro battery
5439 3.25 x 1.25 inch board designed to fit inside 38mm air-frame coupler tube.
5446 EasyMega Specifications
5451 Recording altimeter for model rocketry.
5456 Supports dual deployment and four auxiliary pyro channels
5457 (a total of 6 events).
5462 Barometric pressure sensor good to 100k feet MSL.
5467 1-axis high-g accelerometer for motor characterization, capable of
5473 9-axis IMU including integrated 3-axis accelerometer,
5474 3-axis gyroscope and 3-axis magnetometer.
5479 On-board 8 Megabyte non-volatile memory for flight data storage.
5484 USB interface for battery charging, configuration, and data recovery.
5489 Fully integrated support for Li-Po rechargeable batteries.
5494 Can use either main system Li-Po or optional separate pyro battery
5500 1.25 x 1.25 inch board designed to fit inside 38mm air-frame coupler tube.
5507 TeleMetrum v2 Specifications
5512 Recording altimeter for model rocketry.
5517 Supports dual deployment (can fire 2 ejection charges).
5522 70cm, 40mW ham-band transceiver for telemetry down-link.
5527 Barometric pressure sensor good to 100k feet MSL.
5532 1-axis high-g accelerometer for motor characterization, capable of
5538 On-board, integrated uBlox Max 7 GPS receiver with 5Hz update rate capability.
5543 On-board 8 Megabyte non-volatile memory for flight data storage.
5548 USB interface for battery charging, configuration, and data recovery.
5553 Fully integrated support for Li-Po rechargeable batteries.
5558 Uses Li-Po to fire e-matches, can be modified to support
5559 optional separate pyro battery if needed.
5564 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
5570 <title>TeleMetrum v1 Specifications</title>
5574 Recording altimeter for model rocketry.
5579 Supports dual deployment (can fire 2 ejection charges).
5584 70cm, 10mW ham-band transceiver for telemetry down-link.
5589 Barometric pressure sensor good to 45k feet MSL.
5594 1-axis high-g accelerometer for motor characterization, capable of
5595 +/- 50g using default part.
5600 On-board, integrated GPS receiver with 5Hz update rate capability.
5605 On-board 1 megabyte non-volatile memory for flight data storage.
5610 USB interface for battery charging, configuration, and data recovery.
5615 Fully integrated support for Li-Po rechargeable batteries.
5620 Uses Li-Po to fire e-matches, can be modified to support
5621 optional separate pyro battery if needed.
5626 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
5633 TeleMini v2.0 Specifications
5638 Recording altimeter for model rocketry.
5643 Supports dual deployment (can fire 2 ejection charges).
5648 70cm, 10mW ham-band transceiver for telemetry down-link.
5653 Barometric pressure sensor good to 100k feet MSL.
5658 On-board 1 megabyte non-volatile memory for flight data storage.
5663 USB interface for configuration, and data recovery.
5668 Support for Li-Po rechargeable batteries (using an
5669 external charger), or any 3.7-15V external battery.
5674 Uses Li-Po to fire e-matches, can be modified to support
5675 optional separate pyro battery if needed.
5680 1.5 x .8 inch board designed to fit inside 24mm air-frame coupler tube.
5687 TeleMini v1.0 Specifications
5692 Recording altimeter for model rocketry.
5697 Supports dual deployment (can fire 2 ejection charges).
5702 70cm, 10mW ham-band transceiver for telemetry down-link.
5707 Barometric pressure sensor good to 45k feet MSL.
5712 On-board 5 kilobyte non-volatile memory for flight data storage.
5717 RF interface for configuration, and data recovery.
5722 Support for Li-Po rechargeable batteries, using an external charger.
5727 Uses Li-Po to fire e-matches, can be modified to support
5728 optional separate pyro battery if needed.
5733 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
5740 EasyMini Specifications
5745 Recording altimeter for model rocketry.
5750 Supports dual deployment (can fire 2 ejection charges).
5755 Barometric pressure sensor good to 100k feet MSL.
5760 On-board 1 megabyte non-volatile memory for flight data storage.
5765 USB interface for configuration, and data recovery.
5770 Support for Li-Po rechargeable batteries (using an
5771 external charger), or any 3.7-15V external battery.
5776 Uses Li-Po to fire e-matches, can be modified to support
5777 optional separate pyro battery if needed.
5782 1.5 x .8 inch board designed to fit inside 24mm air-frame coupler tube.
5791 <emphasis>TeleMetrum seems to shut off when disconnected from the
5792 computer.</emphasis> <?linebreak?>
5793 Make sure the battery is adequately charged. Remember the
5794 unit will pull more power than the USB port can deliver before the
5795 GPS enters “locked” mode. The battery charges best when TeleMetrum
5799 <emphasis>It's impossible to stop the TeleDongle when it's in “p” mode, I have
5800 to unplug the USB cable? </emphasis><?linebreak?>
5801 Make sure you have tried to “escape out” of
5802 this mode. If this doesn't work the reboot procedure for the
5803 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
5804 outgoing buffer IF your “escape out” ('~~') does not work.
5805 At this point using either 'ao-view' (or possibly
5806 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
5810 <emphasis>The amber LED (on the TeleMetrum) lights up when both
5811 battery and USB are connected. Does this mean it's charging?
5812 </emphasis><?linebreak?>
5813 Yes, the yellow LED indicates the charging at the 'regular' rate.
5814 If the led is out but the unit is still plugged into a USB port,
5815 then the battery is being charged at a 'trickle' rate.
5818 <emphasis>There are no “dit-dah-dah-dit” sound or lights like the manual
5819 mentions?</emphasis><?linebreak?>
5820 That's the “pad” mode. Weak batteries might be the problem.
5821 It is also possible that the flight computer is horizontal and the
5823 is instead a “dit-dit” meaning 'idle'. For TeleMini, it's possible that
5824 it received a command packet which would have left it in “pad” mode.
5827 <emphasis>How do I save flight data?</emphasis><?linebreak?>
5828 Live telemetry is written to file(s) whenever AltosUI is connected
5829 to the TeleDongle. The file area defaults to ~/TeleMetrum
5830 but is easily changed using the menus in AltosUI. The files that
5831 are written end in '.telem'. The after-flight
5832 data-dumped files will end in .eeprom and represent continuous data
5833 unlike the .telem files that are subject to losses
5834 along the RF data path.
5835 See the above instructions on what and how to save the eeprom stored
5836 data after physically retrieving your altimeter. Make sure to save
5837 the on-board data after each flight; while the TeleMetrum can store
5838 multiple flights, you never know when you'll lose the altimeter...
5842 <title>Notes for Older Software</title>
5845 Before AltosUI was written, using Altus Metrum devices required
5846 some finesse with the Linux command line. There was a limited
5847 GUI tool, ao-view, which provided functionality similar to the
5848 Monitor Flight window in AltosUI, but everything else was a
5849 fairly 80's experience. This appendix includes documentation for
5850 using that software.
5854 Both TeleMetrum and TeleDongle can be directly communicated
5855 with using USB ports. The first thing you should try after getting
5856 both units plugged into to your computer's USB port(s) is to run
5857 'ao-list' from a terminal-window to see what port-device-name each
5858 device has been assigned by the operating system.
5859 You will need this information to access the devices via their
5860 respective on-board firmware and data using other command line
5861 programs in the AltOS software suite.
5864 TeleMini can be communicated with through a TeleDongle device
5865 over the radio link. When first booted, TeleMini listens for a
5866 TeleDongle device and if it receives a packet, it goes into
5867 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
5868 launched. The easiest way to get it talking is to start the
5869 communication link on the TeleDongle and the power up the
5873 To access the device's firmware for configuration you need a terminal
5874 program such as you would use to talk to a modem. The software
5875 authors prefer using the program 'cu' which comes from the UUCP package
5876 on most Unix-like systems such as Linux. An example command line for
5877 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
5878 indicated from running the
5879 ao-list program. Another reasonable terminal program for Linux is
5880 'cutecom'. The default 'escape'
5881 character used by CU (i.e. the character you use to
5882 issue commands to cu itself instead of sending the command as input
5883 to the connected device) is a '~'. You will need this for use in
5884 only two different ways during normal operations. First is to exit
5885 the program by sending a '~.' which is called a 'escape-disconnect'
5886 and allows you to close-out from 'cu'. The
5887 second use will be outlined later.
5890 All of the Altus Metrum devices share the concept of a two level
5891 command set in their firmware.
5892 The first layer has several single letter commands. Once
5893 you are using 'cu' (or 'cutecom') sending (typing) a '?'
5894 returns a full list of these
5895 commands. The second level are configuration sub-commands accessed
5896 using the 'c' command, for
5897 instance typing 'c?' will give you this second level of commands
5898 (all of which require the
5899 letter 'c' to access). Please note that most configuration options
5900 are stored only in Flash memory; TeleDongle doesn't provide any storage
5901 for these options and so they'll all be lost when you unplug it.
5904 Try setting these configuration ('c' or second level menu) values. A good
5905 place to start is by setting your call sign. By default, the boards
5906 use 'N0CALL' which is cute, but not exactly legal!
5907 Spend a few minutes getting comfortable with the units, their
5908 firmware, and 'cu' (or possibly 'cutecom').
5909 For instance, try to send
5910 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
5911 Verify you can connect and disconnect from the units while in your
5912 terminal program by sending the escape-disconnect mentioned above.
5915 To set the radio frequency, use the 'c R' command to specify the
5916 radio transceiver configuration parameter. This parameter is computed
5917 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
5918 the standard calibration reference frequency, 'S', (normally 434.550MHz):
5922 Round the result to the nearest integer value.
5923 As with all 'c' sub-commands, follow this with a 'c w' to write the
5924 change to the parameter block in the on-board flash on
5925 your altimeter board if you want the change to stay in place across reboots.
5928 To set the apogee delay, use the 'c d' command.
5929 As with all 'c' sub-commands, follow this with a 'c w' to write the
5930 change to the parameter block in the on-board DataFlash chip.
5933 To set the main deployment altitude, use the 'c m' command.
5934 As with all 'c' sub-commands, follow this with a 'c w' to write the
5935 change to the parameter block in the on-board DataFlash chip.
5938 To calibrate the radio frequency, connect the UHF antenna port to a
5939 frequency counter, set the board to 434.550MHz, and use the 'C'
5940 command to generate a CW carrier. Wait for the transmitter temperature
5941 to stabilize and the frequency to settle down.
5942 Then, divide 434.550 MHz by the
5943 measured frequency and multiply by the current radio cal value show
5944 in the 'c s' command. For an unprogrammed board, the default value
5945 is 1186611 for cc1111 based products and 7119667 for cc1120
5946 based products. Take the resulting integer and program it using the 'c f'
5947 command. Testing with the 'C' command again should show a carrier
5948 within a few tens of Hertz of the intended frequency.
5949 As with all 'c' sub-commands, follow this with a 'c w' to write the
5950 change to the configuration memory.
5953 Note that the 'reboot' command, which is very useful on the altimeters,
5954 will likely just cause problems with the dongle. The *correct* way
5955 to reset the dongle is just to unplug and re-plug it.
5958 A fun thing to do at the launch site and something you can do while
5959 learning how to use these units is to play with the radio link access
5960 between an altimeter and the TeleDongle. Be aware that you *must* create
5961 some physical separation between the devices, otherwise the link will
5962 not function due to signal overload in the receivers in each device.
5965 Now might be a good time to take a break and read the rest of this
5966 manual, particularly about the two “modes” that the altimeters
5967 can be placed in. TeleMetrum uses the position of the device when booting
5968 up will determine whether the unit is in “pad” or “idle” mode. TeleMini
5969 enters “idle” mode when it receives a command packet within the first 5 seconds
5970 of being powered up, otherwise it enters “pad” mode.
5973 You can access an altimeter in idle mode from the TeleDongle's USB
5974 connection using the radio link
5975 by issuing a 'p' command to the TeleDongle. Practice connecting and
5976 disconnecting ('~~' while using 'cu') from the altimeter. If
5977 you cannot escape out of the “p” command, (by using a '~~' when in
5978 CU) then it is likely that your kernel has issues. Try a newer version.
5981 Using this radio link allows you to configure the altimeter, test
5982 fire e-matches and igniters from the flight line, check pyro-match
5983 continuity and so forth. You can leave the unit turned on while it
5984 is in 'idle mode' and then place the
5985 rocket vertically on the launch pad, walk away and then issue a
5986 reboot command. The altimeter will reboot and start sending data
5987 having changed to the “pad” mode. If the TeleDongle is not receiving
5988 this data, you can disconnect 'cu' from the TeleDongle using the
5989 procedures mentioned above and THEN connect to the TeleDongle from
5990 inside 'ao-view'. If this doesn't work, disconnect from the
5991 TeleDongle, unplug it, and try again after plugging it back in.
5994 In order to reduce the chance of accidental firing of pyrotechnic
5995 charges, the command to fire a charge is intentionally somewhat
5996 difficult to type, and the built-in help is slightly cryptic to
5997 prevent accidental echoing of characters from the help text back at
5998 the board from firing a charge. The command to fire the apogee
5999 drogue charge is 'i DoIt drogue' and the command to fire the main
6000 charge is 'i DoIt main'.
6003 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
6004 and 'ao-view' will both auditorily announce and visually indicate
6006 Now you can launch knowing that you have a good data path and
6007 good satellite lock for flight data and recovery. Remember
6008 you MUST tell ao-view to connect to the TeleDongle explicitly in
6009 order for ao-view to be able to receive data.
6012 The altimeters provide RDF (radio direction finding) tones on
6013 the pad, during descent and after landing. These can be used to
6014 locate the rocket using a directional antenna; the signal
6015 strength providing an indication of the direction from receiver to rocket.
6018 TeleMetrum also provides GPS tracking data, which can further simplify
6019 locating the rocket once it has landed. (The last good GPS data
6020 received before touch-down will be on the data screen of 'ao-view'.)
6023 Once you have recovered the rocket you can download the eeprom
6024 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
6025 either a USB cable or over the radio link using TeleDongle.
6026 And by following the man page for 'ao-postflight' you can create
6027 various data output reports, graphs, and even KML data to see the
6028 flight trajectory in Google-earth. (Moving the viewing angle making
6029 sure to connect the yellow lines while in Google-earth is the proper
6033 As for ao-view.... some things are in the menu but don't do anything
6034 very useful. The developers have stopped working on ao-view to focus
6035 on a new, cross-platform ground station program. So ao-view may or
6036 may not be updated in the future. Mostly you just use
6037 the Log and Device menus. It has a wonderful display of the incoming
6038 flight data and I am sure you will enjoy what it has to say to you
6039 once you enable the voice output!
6043 <title>Drill Templates</title>
6045 These images, when printed, provide precise templates for the
6046 mounting holes in Altus Metrum flight computers
6049 <title>TeleMega template</title>
6051 TeleMega has overall dimensions of 1.250 x 3.250 inches, and
6052 the mounting holes are sized for use with 4-40 or M3 screws.
6055 <mediaobject id="TeleMegaTemplate">
6057 <imagedata format="SVG" fileref="telemega.svg"
6058 scalefit="0" scale="100" align="center" />
6064 <title>EasyMega template</title>
6066 EasyMega has overall dimensions of 1.250 x 2.250 inches, and
6067 the mounting holes are sized for use with 4-40 or M3 screws.
6070 <mediaobject id="EasyMegaTemplate">
6072 <imagedata format="SVG" fileref="easymega.svg"
6073 scalefit="0" scale="100" align="center" />
6079 <title>TeleMetrum template</title>
6081 TeleMetrum has overall dimensions of 1.000 x 2.750 inches, and the
6082 mounting holes are sized for use with 4-40 or M3 screws.
6085 <mediaobject id="TeleMetrumTemplate">
6087 <imagedata format="SVG" fileref="telemetrum.svg"
6088 scalefit="0" scale="100" align="center" />
6094 <title>TeleMini v2/EasyMini template</title>
6096 TeleMini v2 and EasyMini have overall dimensions of 0.800 x 1.500 inches, and the
6097 mounting holes are sized for use with 4-40 or M3 screws.
6100 <mediaobject id="MiniTemplate">
6102 <imagedata format="SVG" fileref="easymini.svg"
6103 scalefit="0" scale="100" align="center" />
6109 <title>TeleMini v1 template</title>
6111 TeleMini has overall dimensions of 0.500 x 1.500 inches, and the
6112 mounting holes are sized for use with 2-56 or M2 screws.
6115 <mediaobject id="TeleMiniTemplate">
6117 <imagedata format="SVG" fileref="telemini.svg"
6118 scalefit="0" scale="100" align="center" />
6125 <title>Calibration</title>
6127 There are only two calibrations required for TeleMetrum and
6128 TeleMega, and only one for EasyMega, TeleDongle, TeleMini and EasyMini.
6129 All boards are shipped from the factory pre-calibrated, but
6130 the procedures are documented here in case they are ever
6131 needed. Re-calibration is not supported by AltosUI, you must
6132 connect to the board with a serial terminal program and
6133 interact directly with the on-board command interpreter to
6137 <title>Radio Frequency</title>
6139 The radio frequency is synthesized from a clock based on the
6140 crystal on the board. The actual frequency of this oscillator
6141 must be measured to generate a calibration constant. While our
6143 bandwidth is wide enough to allow boards to communicate even when
6144 their oscillators are not on exactly the same frequency, performance
6145 is best when they are closely matched.
6146 Radio frequency calibration requires a calibrated frequency counter.
6147 Fortunately, once set, the variation in frequency due to aging and
6148 temperature changes is small enough that re-calibration by customers
6149 should generally not be required.
6152 To calibrate the radio frequency, connect the UHF antenna
6153 port to a frequency counter, set the board to 434.550MHz,
6154 and use the 'C' command in the on-board command interpreter
6155 to generate a CW carrier. For USB-enabled boards, this is
6156 best done over USB. For TeleMini v1, note that the only way
6157 to escape the 'C' command is via power cycle since the board
6158 will no longer be listening for commands once it starts
6159 generating a CW carrier.
6162 Wait for the transmitter temperature to stabilize and the frequency
6163 to settle down. Then, divide 434.550 MHz by the
6164 measured frequency and multiply by the current radio cal value show
6165 in the 'c s' command. For an unprogrammed board, the default value
6166 is 1186611. Take the resulting integer and program it using the 'c f'
6167 command. Testing with the 'C' command again should show a carrier
6168 within a few tens of Hertz of the intended frequency.
6169 As with all 'c' sub-commands, follow this with a 'c w' to write the
6170 change to the parameter block in the on-board storage chip.
6173 Note that any time you re-do the radio frequency calibration, the
6174 radio frequency is reset to the default 434.550 Mhz. If you want
6175 to use another frequency, you will have to set that again after
6176 calibration is completed.
6180 <title>TeleMetrum, TeleMega and EasyMega Accelerometers</title>
6182 While barometric sensors are factory-calibrated,
6183 accelerometers are not, and so each must be calibrated once
6184 installed in a flight computer. Explicitly calibrating the
6185 accelerometers also allows us to load any compatible device.
6186 We perform a two-point calibration using gravity.
6189 To calibrate the acceleration sensor, use the 'c a 0' command. You
6190 will be prompted to orient the board vertically with the UHF antenna
6191 up and press a key, then to orient the board vertically with the
6192 UHF antenna down and press a key. Note that the accuracy of this
6193 calibration depends primarily on how perfectly vertical and still
6194 the board is held during the cal process. As with all 'c'
6195 sub-commands, follow this with a 'c w' to write the
6196 change to the parameter block in the on-board DataFlash chip.
6199 The +1g and -1g calibration points are included in each telemetry
6200 frame and are part of the header stored in onboard flash to be
6201 downloaded after flight. We always store and return raw ADC
6202 samples for each sensor... so nothing is permanently “lost” or
6203 “damaged” if the calibration is poor.
6206 In the unlikely event an accel cal goes badly, it is possible
6207 that TeleMetrum, TeleMega or EasyMega may always come up in 'pad mode'
6208 and as such not be listening to either the USB or radio link.
6209 If that happens, there is a special hook in the firmware to
6210 force the board back in to 'idle mode' so you can re-do the
6211 cal. To use this hook, you just need to ground the SPI clock
6212 pin at power-on. This pin is available as pin 2 on the 8-pin
6213 companion connector, and pin 1 is ground. So either
6214 carefully install a fine-gauge wire jumper between the two
6215 pins closest to the index hole end of the 8-pin connector, or
6216 plug in the programming cable to the 8-pin connector and use
6217 a small screwdriver or similar to short the two pins closest
6218 to the index post on the 4-pin end of the programming cable,
6219 and power up the board. It should come up in 'idle mode'
6220 (two beeps), allowing a re-cal.
6225 <title>Igniter Current</title>
6227 The question "how much igniter current can Altus Metrum products
6228 handle?" comes up fairly frequently. The short answer is "more than
6229 you're likely to need", the remainder of this appendix provides a
6233 <title>Current Products</title>
6235 The FET switches we're using on all of our current products that
6236 have pyro channels are the Vishay Siliconix Si7232DN. These parts
6237 have exceptionally low Rds(on) values, better than 0.02 ohms! That
6238 means they aren't making a lot of heat... and the limit on current
6239 is "package limited", meaning it's all about how much you can heat
6240 the die before something breaks.
6243 Cutting to the chase, the Si7232DN specs are 25 amps <emphasis>continuous</emphasis> at
6244 20V at a temperature of 25C. In pulsed mode, they're rated for 40A.
6245 However, those specs are a little mis-leading because it really is
6246 all about the heat generated... you can get something like 85A
6247 through one briefly. Note that a typical commercial e-match only
6248 needed about 13 microseconds to fire in tests on my bench a couple
6252 So a great plan is to use something like an e-match as the initiator
6253 and build up pyrogen(s) as required to actually light what you're
6254 trying to light... But if you want to use a high-current igniter,
6255 we can probably handle it!
6259 <title>Version 1 Products</title>
6261 The FET switches used on TeleMetrum v1 and TeleMini v1 products
6262 were Fairchild FDS9926A. The Rds(on) values under our operating
6263 conditions are on the order of 0.04 ohms. These parts were rated
6264 for a continuous current-carrying capacity of 6.5A, and a pulsed
6265 current capacity of 20A.
6268 As with the more modern parts, the real limit is based on the heat
6269 generated in the part during the firing interval. So, while the
6270 specs on these parts aren't as good as the ones we use on current
6271 products, they were still great, and we never had a complaint about
6272 current carrying capacity with any of our v1 boards.
6277 <title>Release Notes</title>
6279 <title>Version 1.6.1</title>
6281 xmlns:xi="http://www.w3.org/2001/XInclude"
6282 href="release-notes-1.6.1.xsl"
6283 xpointer="xpointer(/article/*)"/>
6286 <title>Version 1.6</title>
6288 xmlns:xi="http://www.w3.org/2001/XInclude"
6289 href="release-notes-1.6.xsl"
6290 xpointer="xpointer(/article/*)"/>
6293 <title>Version 1.5</title>
6295 xmlns:xi="http://www.w3.org/2001/XInclude"
6296 href="release-notes-1.5.xsl"
6297 xpointer="xpointer(/article/*)"/>
6300 <title>Version 1.4.1</title>
6302 xmlns:xi="http://www.w3.org/2001/XInclude"
6303 href="release-notes-1.4.1.xsl"
6304 xpointer="xpointer(/article/*)"/>
6307 <title>Version 1.4</title>
6309 xmlns:xi="http://www.w3.org/2001/XInclude"
6310 href="release-notes-1.4.xsl"
6311 xpointer="xpointer(/article/*)"/>
6314 <title>Version 1.3.2</title>
6316 xmlns:xi="http://www.w3.org/2001/XInclude"
6317 href="release-notes-1.3.2.xsl"
6318 xpointer="xpointer(/article/*)"/>
6321 <title>Version 1.3.1</title>
6323 xmlns:xi="http://www.w3.org/2001/XInclude"
6324 href="release-notes-1.3.1.xsl"
6325 xpointer="xpointer(/article/*)"/>
6328 <title>Version 1.3</title>
6330 xmlns:xi="http://www.w3.org/2001/XInclude"
6331 href="release-notes-1.3.xsl"
6332 xpointer="xpointer(/article/*)"/>
6335 <title>Version 1.2.1</title>
6337 xmlns:xi="http://www.w3.org/2001/XInclude"
6338 href="release-notes-1.2.1.xsl"
6339 xpointer="xpointer(/article/*)"/>
6342 <title>Version 1.2</title>
6344 xmlns:xi="http://www.w3.org/2001/XInclude"
6345 href="release-notes-1.2.xsl"
6346 xpointer="xpointer(/article/*)"/>
6349 <title>Version 1.1.1</title>
6351 xmlns:xi="http://www.w3.org/2001/XInclude"
6352 href="release-notes-1.1.1.xsl"
6353 xpointer="xpointer(/article/*)"/>
6356 <title>Version 1.1</title>
6358 xmlns:xi="http://www.w3.org/2001/XInclude"
6359 href="release-notes-1.1.xsl"
6360 xpointer="xpointer(/article/*)"/>
6363 <title>Version 1.0.1</title>
6365 xmlns:xi="http://www.w3.org/2001/XInclude"
6366 href="release-notes-1.0.1.xsl"
6367 xpointer="xpointer(/article/*)"/>
6370 <title>Version 0.9.2</title>
6372 xmlns:xi="http://www.w3.org/2001/XInclude"
6373 href="release-notes-0.9.2.xsl"
6374 xpointer="xpointer(/article/*)"/>
6377 <title>Version 0.9</title>
6379 xmlns:xi="http://www.w3.org/2001/XInclude"
6380 href="release-notes-0.9.xsl"
6381 xpointer="xpointer(/article/*)"/>
6384 <title>Version 0.8</title>
6386 xmlns:xi="http://www.w3.org/2001/XInclude"
6387 href="release-notes-0.8.xsl"
6388 xpointer="xpointer(/article/*)"/>
6391 <title>Version 0.7.1</title>
6393 xmlns:xi="http://www.w3.org/2001/XInclude"
6394 href="release-notes-0.7.1.xsl"
6395 xpointer="xpointer(/article/*)"/>
6400 <!-- LocalWords: Altusmetrum
projects / fw / altos / blob