1 <?xml version="1.0" encoding="utf-8"?>
2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "/usr/share/xml/docbook/schema/dtd/4.5/docbookx.dtd">
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>1.3.2</revnumber>
45 <date>24 January 2014</date>
47 Bug fixes for TeleMega and AltosUI.
51 <revnumber>1.3.1</revnumber>
52 <date>21 January 2014</date>
54 Bug fixes for TeleMega and TeleMetrum v2.0 along with a few
55 small UI improvements.
59 <revnumber>1.3</revnumber>
60 <date>12 November 2013</date>
62 Updated for software version 1.3. Version 1.3 adds support
63 for TeleMega, TeleMetrum v2.0, TeleMini v2.0 and EasyMini
64 and fixes bugs in AltosUI and the AltOS firmware.
68 <revnumber>1.2.1</revnumber>
69 <date>21 May 2013</date>
71 Updated for software version 1.2. Version 1.2 adds support
72 for TeleBT and AltosDroid. It also adds a few minor features
73 and fixes bugs in AltosUI and the AltOS firmware.
77 <revnumber>1.2</revnumber>
78 <date>18 April 2013</date>
80 Updated for software version 1.2. Version 1.2 adds support
81 for MicroPeak and the MicroPeak USB interface.
85 <revnumber>1.1.1</revnumber>
86 <date>16 September 2012</date>
88 Updated for software version 1.1.1 Version 1.1.1 fixes a few
89 bugs found in version 1.1.
93 <revnumber>1.1</revnumber>
94 <date>13 September 2012</date>
96 Updated for software version 1.1. Version 1.1 has new
97 features but is otherwise compatible with version 1.0.
101 <revnumber>1.0</revnumber>
102 <date>24 August 2011</date>
104 Updated for software version 1.0. Note that 1.0 represents a
105 telemetry format change, meaning both ends of a link
106 (TeleMetrum/TeleMini and TeleDongle) must be updated or
107 communications will fail.
111 <revnumber>0.9</revnumber>
112 <date>18 January 2011</date>
114 Updated for software version 0.9. Note that 0.9 represents a
115 telemetry format change, meaning both ends of a link (TeleMetrum and
116 TeleDongle) must be updated or communications will fail.
120 <revnumber>0.8</revnumber>
121 <date>24 November 2010</date>
122 <revremark>Updated for software version 0.8 </revremark>
127 <title>Acknowledgments</title>
129 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing “The
130 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
131 Kit” which formed the basis of the original Getting Started chapter
132 in this manual. Bob was one of our first customers for a production
133 TeleMetrum, and his continued enthusiasm and contributions
134 are immensely gratifying and highly appreciated!
137 And thanks to Anthony (AJ) Towns for major contributions including
138 the AltosUI graphing and site map code and associated documentation.
139 Free software means that our customers and friends can become our
140 collaborators, and we certainly appreciate this level of
144 Have fun using these products, and we hope to meet all of you
145 out on the rocket flight line somewhere.
148 NAR #87103, TRA #12201
150 Keith Packard, KD7SQG
151 NAR #88757, TRA #12200
156 <title>Introduction and Overview</title>
158 Welcome to the Altus Metrum community! Our circuits and software reflect
159 our passion for both hobby rocketry and Free Software. We hope their
160 capabilities and performance will delight you in every way, but by
161 releasing all of our hardware and software designs under open licenses,
162 we also hope to empower you to take as active a role in our collective
166 The first device created for our community was TeleMetrum, a dual
167 deploy altimeter with fully integrated GPS and radio telemetry
168 as standard features, and a “companion interface” that will
169 support optional capabilities in the future. The latest version
170 of TeleMetrum, v2.0, has all of the same features but with
171 improved sensors and radio to offer increased performance.
174 Our second device was TeleMini, a dual deploy altimeter with
175 radio telemetry and radio direction finding. The first version
176 of this device was only 13mm by 38mm (½ inch by 1½ inches) and
177 could fit easily in an 18mm air-frame. The latest version, v2.0,
178 includes a beeper, USB data download and extended on-board
179 flight logging, along with an improved barometric sensor.
182 TeleMega is our most sophisticated device, including six pyro
183 channels (four of which are fully programmable), integrated GPS,
184 integrated gyroscopes for staging/air-start inhibit and high
185 performance telemetry.
188 EasyMini is a dual-deploy altimeter with logging and built-in
192 TeleDongle was our first ground station, providing a USB to RF
193 interfaces for communicating with the altimeters. Combined with
194 your choice of antenna and notebook computer, TeleDongle and our
195 associated user interface software form a complete ground
196 station capable of logging and displaying in-flight telemetry,
197 aiding rocket recovery, then processing and archiving flight
198 data for analysis and review.
201 For a slightly more portable ground station experience that also
202 provides direct rocket recovery support, TeleBT offers flight
203 monitoring and data logging using a Bluetooth™ connection between
204 the receiver and an Android device that has the AltosDroid
205 application installed from the Google Play store.
208 More products will be added to the Altus Metrum family over time, and
209 we currently envision that this will be a single, comprehensive manual
210 for the entire product family.
214 <title>Getting Started</title>
216 The first thing to do after you check the inventory of parts in your
217 “starter kit” is to charge the battery.
220 For TeleMetrum and TeleMega, the battery can be charged by plugging it into the
221 corresponding socket of the device and then using the USB
222 cable to plug the flight computer into your computer's USB socket. The
223 on-board circuitry will charge the battery whenever it is plugged
224 in, because the on-off switch does NOT control the
228 On TeleMetrum v1 boards, when the GPS chip is initially
229 searching for satellites, TeleMetrum will consume more current
230 than it pulls from the USB port, so the battery must be
231 attached in order to get satellite lock. Once GPS is locked,
232 the current consumption goes back down enough to enable charging
233 while running. So it's a good idea to fully charge the battery
234 as your first item of business so there is no issue getting and
235 maintaining satellite lock. The yellow charge indicator led
236 will go out when the battery is nearly full and the charger goes
237 to trickle charge. It can take several hours to fully recharge a
238 deeply discharged battery.
241 TeleMetrum v2.0 and TeleMega use a higher power battery charger,
242 allowing them to charge the battery while running the board at
243 maximum power. When the battery is charging, or when the board
244 is consuming a lot of power, the red LED will be lit. When the
245 battery is fully charged, the green LED will be lit. When the
246 battery is damaged or missing, both LEDs will be lit, which
250 The Lithium Polymer TeleMini and EasyMini battery can be charged by
251 disconnecting it from the board and plugging it into a
252 standalone battery charger such as the LipoCharger product
253 included in TeleMini Starter Kits, and connecting that via a USB
254 cable to a laptop or other USB power source.
257 You can also choose to use another battery with TeleMini v2.0
258 and EasyMini, anything supplying between 4 and 12 volts should
259 work fine (like a standard 9V battery), but if you are planning
260 to fire pyro charges, ground testing is required to verify that
261 the battery supplies enough current to fire your chosen e-matches.
264 The other active device in the starter kit is the TeleDongle USB to
265 RF interface. If you plug it in to your Mac or Linux computer it should
266 “just work”, showing up as a serial port device. Windows systems need
267 driver information that is part of the AltOS download to know that the
268 existing USB modem driver will work. We therefore recommend installing
269 our software before plugging in TeleDongle if you are using a Windows
270 computer. If you are using an older version of Linux and are having
271 problems, try moving to a fresher kernel (2.6.33 or newer).
274 Next you should obtain and install the AltOS software. The AltOS
275 distribution includes the AltosUI ground station program, current
277 images for all of the hardware, and a number of standalone
278 utilities that are rarely needed. Pre-built binary packages are
279 available for Linux, Microsoft Windows, and recent MacOSX
280 versions. Full source code and build instructions are also
281 available. The latest version may always be downloaded from
282 <ulink url="http://altusmetrum.org/AltOS"/>.
285 If you're using a TeleBT instead of the TeleDongle, you'll want to
286 install the AltosDroid application from the Google Play store on an
287 Android device. You don't need a data plan to use AltosDroid, but
288 without network access, the Map view will be less useful as it
289 won't contain any map data. You can also use TeleBT connected
290 over USB with your laptop computer; it acts exactly like a
291 TeleDongle. Anywhere this manual talks about TeleDongle, you can
292 also read that as 'and TeleBT when connected via USB'.
296 <title>Handling Precautions</title>
298 All Altus Metrum products are sophisticated electronic devices.
299 When handled gently and properly installed in an air-frame, they
300 will deliver impressive results. However, as with all electronic
301 devices, there are some precautions you must take.
304 The Lithium Polymer rechargeable batteries have an
305 extraordinary power density. This is great because we can fly with
306 much less battery mass than if we used alkaline batteries or previous
307 generation rechargeable batteries... but if they are punctured
308 or their leads are allowed to short, they can and will release their
310 Thus we recommend that you take some care when handling our batteries
311 and consider giving them some extra protection in your air-frame. We
312 often wrap them in suitable scraps of closed-cell packing foam before
313 strapping them down, for example.
316 The barometric sensors used on all of our flight computers are
317 sensitive to sunlight. In normal mounting situations, the baro sensor
318 and all of the other surface mount components
319 are “down” towards whatever the underlying mounting surface is, so
320 this is not normally a problem. Please consider this when designing an
321 installation in an air-frame with a see-through plastic payload bay. It
322 is particularly important to
323 consider this with TeleMini v1.0, both because the baro sensor is on the
324 “top” of the board, and because many model rockets with payload bays
325 use clear plastic for the payload bay! Replacing these with an opaque
326 cardboard tube, painting them, or wrapping them with a layer of masking
327 tape are all reasonable approaches to keep the sensor out of direct
331 The barometric sensor sampling port must be able to “breathe”,
332 both by not being covered by foam or tape or other materials that might
333 directly block the hole on the top of the sensor, and also by having a
334 suitable static vent to outside air.
337 As with all other rocketry electronics, Altus Metrum altimeters must
338 be protected from exposure to corrosive motor exhaust and ejection
343 <title>Altus Metrum Hardware</title>
345 <title>General Usage Instructions</title>
347 Here are general instructions for hooking up an Altus Metrum
348 flight computer. Instructions specific to each model will be
349 found in the section devoted to that model below.
352 To prevent electrical interference from affecting the
353 operation of the flight computer, it's important to always
354 twist pairs of wires connected to the board. Twist the switch
355 leads, the pyro leads and the battery leads. This reduces
356 interference through a mechanism called common mode rejection.
359 <title>Hooking Up Lithium Polymer Batteries</title>
361 All Altus Metrum flight computers have a two pin JST PH
362 series connector to connect up a single-cell Lithium Polymer
363 cell (3.7V nominal). You can purchase matching batteries
364 from the Altus Metrum store, or other vendors, or you can
365 make your own. Pin 1 of the connector is positive, pin 2 is
366 negative. Spark Fun sells a cable with the connector
367 attached, which they call a <ulink
368 url="https://www.sparkfun.com/products/9914">JST Jumper 2
369 Wire Assembly</ulink>.
372 Many RC vendors also sell lithium polymer batteries with
373 this same connector. All that we have found use the opposite
374 polarity, and if you use them that way, you will damage or
375 destroy the flight computer.
379 <title>Hooking Up Pyro Charges</title>
381 Altus Metrum flight computers always have two screws for
382 each pyro charge. This means you shouldn't need to put two
383 wires into a screw terminal or connect leads from pyro
384 charges together externally.
387 On the flight computer, one lead from each charge is hooked
388 to the positive battery terminal through the power switch.
389 The other lead is connected through the pyro circuit, which
390 is connected to the negative battery terminal when the pyro
395 <title>Hooking Up a Power Switch</title>
397 Altus Metrum flight computers need an external power switch
398 to turn them on. This disconnects both the computer and the
399 pyro charges from the battery, preventing the charges from
400 firing when in the Off position. The switch is in-line with
401 the positive battery terminal.
404 <title>Using an External Active Switch Circuit</title>
406 You can use an active switch circuit, such as the
407 Featherweight Magnetic Switch, with any Altus Metrum
408 flight computer. These require three connections, one to
409 the battery, one to the positive power input on the flight
410 computer and one to ground. Find instructions on how to
411 hook these up for each flight computer below. The follow
412 the instructions that come with your active switch to
418 <title>Using a Separate Pyro Battery</title>
420 As mentioned above in the section on hooking up pyro
421 charges, one lead for each of the pyro charges is connected
422 through the power switch directly to the positive battery
423 terminal. The other lead is connected to the pyro circuit,
424 which connects it to the negative battery terminal when the
425 pyro circuit is fired. The pyro circuit on all of the flight
426 computers is designed to handle up to 16V.
429 To use a separate pyro battery, connect the negative pyro
430 battery terminal to the flight computer ground terminal,
431 the positive battery terminal to the igniter and the other
432 igniter lead to the negative pyro terminal on the flight
433 computer. When the pyro channel fires, it will complete the
434 circuit between the negative pyro terminal and the ground
435 terminal, firing the igniter. Specific instructions on how
436 to hook this up will be found in each section below.
440 <title>Using a Different Kind of Battery</title>
442 EasyMini and TeleMini v2 are designed to use either a
443 lithium polymer battery or any other battery producing
444 between 4 and 12 volts, such as a rectangular 9V
445 battery. TeleMega and TeleMetrum are not designed for this,
446 and must only be powered by a lithium polymer battery. Find
447 instructions on how to use other batteries in the EasyMini
448 and TeleMini sections below.
453 <title>Specifications</title>
455 Here's the full set of Altus Metrum products, both in
456 production and retired.
459 <title>Altus Metrum Electronics</title>
460 <?dbfo keep-together="always"?>
461 <tgroup cols='8' align='center' colsep='1' rowsep='1'>
462 <colspec align='center' colwidth='*' colname='Device'/>
463 <colspec align='center' colwidth='*' colname='Barometer'/>
464 <colspec align='center' colwidth='*' colname='Z-axis accelerometer'/>
465 <colspec align='center' colwidth='*' colname='GPS'/>
466 <colspec align='center' colwidth='*' colname='3D sensors'/>
467 <colspec align='center' colwidth='*' colname='Storage'/>
468 <colspec align='center' colwidth='*' colname='RF'/>
469 <colspec align='center' colwidth='*' colname='Battery'/>
472 <entry align='center'>Device</entry>
473 <entry align='center'>Barometer</entry>
474 <entry align='center'>Z-axis accelerometer</entry>
475 <entry align='center'>GPS</entry>
476 <entry align='center'>3D sensors</entry>
477 <entry align='center'>Storage</entry>
478 <entry align='center'>RF Output</entry>
479 <entry align='center'>Battery</entry>
484 <entry>TeleMetrum v1.0</entry>
485 <entry><para>MP3H6115 10km (33k')</para></entry>
486 <entry><para>MMA2202 50g</para></entry>
487 <entry>SkyTraq</entry>
494 <entry>TeleMetrum v1.1</entry>
495 <entry><para>MP3H6115 10km (33k')</para></entry>
496 <entry><para>MMA2202 50g</para></entry>
497 <entry>SkyTraq</entry>
504 <entry>TeleMetrum v1.2</entry>
505 <entry><para>MP3H6115 10km (33k')</para></entry>
506 <entry><para>ADXL78 70g</para></entry>
507 <entry>SkyTraq</entry>
514 <entry>TeleMetrum v2.0</entry>
515 <entry><para>MS5607 30km (100k')</para></entry>
516 <entry><para>MMA6555 102g</para></entry>
517 <entry>uBlox Max-7Q</entry>
524 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
525 <entry><para>MP3H6115 10km (33k')</para></entry>
534 <entry>TeleMini <?linebreak?>v2.0</entry>
535 <entry><para>MS5607 30km (100k')</para></entry>
541 <entry>3.7-12V</entry>
544 <entry>EasyMini <?linebreak?>v1.0</entry>
545 <entry><para>MS5607 30km (100k')</para></entry>
551 <entry>3.7-12V</entry>
554 <entry>TeleMega <?linebreak?>v1.0</entry>
555 <entry><para>MS5607 30km (100k')</para></entry>
556 <entry><para>MMA6555 102g</para></entry>
557 <entry>uBlox Max-7Q</entry>
558 <entry><para>MPU6000 HMC5883</para></entry>
567 <title>Altus Metrum Boards</title>
568 <?dbfo keep-together="always"?>
569 <tgroup cols='6' align='center' colsep='1' rowsep='1'>
570 <colspec align='center' colwidth='*' colname='Device'/>
571 <colspec align='center' colwidth='*' colname='Connectors'/>
572 <colspec align='center' colwidth='*' colname='Screw Terminals'/>
573 <colspec align='center' colwidth='*' colname='Width'/>
574 <colspec align='center' colwidth='*' colname='Length'/>
575 <colspec align='center' colwidth='*' colname='Tube Size'/>
578 <entry align='center'>Device</entry>
579 <entry align='center'>Connectors</entry>
580 <entry align='center'>Screw Terminals</entry>
581 <entry align='center'>Width</entry>
582 <entry align='center'>Length</entry>
583 <entry align='center'>Tube Size</entry>
588 <entry>TeleMetrum</entry>
592 Companion<?linebreak?>
596 <entry><para>Apogee pyro <?linebreak?>Main pyro <?linebreak?>Switch</para></entry>
597 <entry>1 inch (2.54cm)</entry>
598 <entry>2 ¾ inch (6.99cm)</entry>
599 <entry>29mm coupler</entry>
602 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
609 Apogee pyro <?linebreak?>
612 <entry>½ inch (1.27cm)</entry>
613 <entry>1½ inch (3.81cm)</entry>
614 <entry>18mm coupler</entry>
617 <entry>TeleMini <?linebreak?>v2.0</entry>
625 Apogee pyro <?linebreak?>
626 Main pyro <?linebreak?>
627 Battery <?linebreak?>
630 <entry>0.8 inch (2.03cm)</entry>
631 <entry>1½ inch (3.81cm)</entry>
632 <entry>24mm coupler</entry>
635 <entry>EasyMini</entry>
642 Apogee pyro <?linebreak?>
643 Main pyro <?linebreak?>
644 Battery <?linebreak?>
647 <entry>0.8 inch (2.03cm)</entry>
648 <entry>1½ inch (3.81cm)</entry>
649 <entry>24mm coupler</entry>
652 <entry>TeleMega</entry>
656 Companion<?linebreak?>
661 Apogee pyro <?linebreak?>
662 Main pyro<?linebreak?>
663 Pyro A-D<?linebreak?>
667 <entry>1¼ inch (3.18cm)</entry>
668 <entry>3¼ inch (8.26cm)</entry>
669 <entry>38mm coupler</entry>
676 <title>TeleMetrum</title>
680 <imagedata fileref="telemetrum-v1.1-thside.jpg" width="5.5in" scalefit="1"/>
685 TeleMetrum is a 1 inch by 2¾ inch circuit board. It was designed to
686 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
687 small in diameter may require some creativity in mounting and wiring
688 to succeed! The presence of an accelerometer means TeleMetrum should
689 be aligned along the flight axis of the airframe, and by default the ¼
690 wave UHF wire antenna should be on the nose-cone end of the board. The
691 antenna wire is about 7 inches long, and wiring for a power switch and
692 the e-matches for apogee and main ejection charges depart from the
693 fin can end of the board, meaning an ideal “simple” avionics
694 bay for TeleMetrum should have at least 10 inches of interior length.
697 <title>TeleMetrum Screw Terminals</title>
699 TeleMetrum has six screw terminals on the end of the board
700 opposite the telemetry antenna. Two are for the power
701 switch, and two each for the apogee and main igniter
702 circuits. Using the picture above and starting from the top,
703 the terminals are as follows:
706 <title>TeleMetrum Screw Terminals</title>
707 <?dbfo keep-together="always"?>
708 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
709 <colspec align='center' colwidth='*' colname='Pin #'/>
710 <colspec align='center' colwidth='2*' colname='Pin Name'/>
711 <colspec align='left' colwidth='5*' colname='Description'/>
714 <entry align='center'>Terminal #</entry>
715 <entry align='center'>Terminal Name</entry>
716 <entry align='center'>Description</entry>
722 <entry>Switch Output</entry>
723 <entry>Switch connection to flight computer</entry>
727 <entry>Switch Input</entry>
728 <entry>Switch connection to positive battery terminal</entry>
732 <entry>Main +</entry>
733 <entry>Main pyro channel common connection to battery +</entry>
737 <entry>Main -</entry>
738 <entry>Main pyro channel connection to pyro circuit</entry>
742 <entry>Apogee +</entry>
743 <entry>Apogee pyro channel common connection to battery +</entry>
747 <entry>Apogee -</entry>
748 <entry>Apogee pyro channel connection to pyro circuit</entry>
755 <title>Using a Separate Pyro Battery with TeleMetrum</title>
757 As described above, using an external pyro battery involves
758 connecting the negative battery terminal to the flight
759 computer ground, connecting the positive battery terminal to
760 one of the igniter leads and connecting the other igniter
761 lead to the per-channel pyro circuit connection.
764 To connect the negative battery terminal to the TeleMetrum
765 ground, insert a small piece of wire, 24 to 28 gauge
766 stranded, into the GND hole just above the screw terminal
767 strip and solder it in place.
770 Connecting the positive battery terminal to the pyro
771 charges must be done separate from TeleMetrum, by soldering
772 them together or using some other connector.
775 The other lead from each pyro charge is then inserted into
776 the appropriate per-pyro channel screw terminal (terminal 4 for the
777 Main charge, terminal 6 for the Apogee charge).
781 <title>Using an Active Switch with TeleMetrum</title>
783 As explained above, an external active switch requires three
784 connections, one to the positive battery terminal, one to
785 the flight computer positive input and one to ground.
788 The positive battery terminal is available on screw terminal
789 2, the positive flight computer input is on terminal 1. To
790 hook a lead to ground, solder a piece of wire, 24 to 28
791 gauge stranded, to the GND hole just above terminal 1.
796 <title>TeleMini v1.0</title>
800 <imagedata fileref="telemini-v1-top.jpg" width="5.5in" scalefit="1"/>
805 TeleMini v1.0 is ½ inches by 1½ inches. It was
806 designed to fit inside an 18mm air-frame tube, but using it in
807 a tube that small in diameter may require some creativity in
808 mounting and wiring to succeed! Since there is no
809 accelerometer, TeleMini can be mounted in any convenient
810 orientation. The default ¼ wave UHF wire antenna attached to
811 the center of one end of the board is about 7 inches long. Two
812 wires for the power switch are connected to holes in the
813 middle of the board. Screw terminals for the e-matches for
814 apogee and main ejection charges depart from the other end of
815 the board, meaning an ideal “simple” avionics bay for TeleMini
816 should have at least 9 inches of interior length.
819 <title>TeleMini v1.0 Screw Terminals</title>
821 TeleMini v1.0 has four screw terminals on the end of the
822 board opposite the telemetry antenna. Two are for the apogee
823 and two are for main igniter circuits. There are also wires
824 soldered to the board for the power switch. Using the
825 picture above and starting from the top for the terminals
826 and from the left for the power switch wires, the
827 connections are as follows:
830 <title>TeleMini v1.0 Connections</title>
831 <?dbfo keep-together="always"?>
832 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
833 <colspec align='center' colwidth='*' colname='Pin #'/>
834 <colspec align='center' colwidth='2*' colname='Pin Name'/>
835 <colspec align='left' colwidth='5*' colname='Description'/>
838 <entry align='center'>Terminal #</entry>
839 <entry align='center'>Terminal Name</entry>
840 <entry align='center'>Description</entry>
846 <entry>Apogee -</entry>
847 <entry>Apogee pyro channel connection to pyro circuit</entry>
851 <entry>Apogee +</entry>
852 <entry>Apogee pyro channel common connection to battery +</entry>
856 <entry>Main -</entry>
857 <entry>Main pyro channel connection to pyro circuit</entry>
861 <entry>Main +</entry>
862 <entry>Main pyro channel common connection to battery +</entry>
866 <entry>Switch Output</entry>
867 <entry>Switch connection to flight computer</entry>
871 <entry>Switch Input</entry>
872 <entry>Switch connection to positive battery terminal</entry>
879 <title>Using a Separate Pyro Battery with TeleMini v1.0</title>
881 As described above, using an external pyro battery involves
882 connecting the negative battery terminal to the flight
883 computer ground, connecting the positive battery terminal to
884 one of the igniter leads and connecting the other igniter
885 lead to the per-channel pyro circuit connection. Because
886 there is no solid ground connection to use on TeleMini, this
890 The only available ground connection on TeleMini v1.0 are
891 the two mounting holes next to the telemetry
892 antenna. Somehow connect a small piece of wire to one of
893 those holes and hook it to the negative pyro battery terminal.
896 Connecting the positive battery terminal to the pyro
897 charges must be done separate from TeleMini v1.0, by soldering
898 them together or using some other connector.
901 The other lead from each pyro charge is then inserted into
902 the appropriate per-pyro channel screw terminal (terminal 3 for the
903 Main charge, terminal 1 for the Apogee charge).
907 <title>Using an Active Switch with TeleMini v1.0</title>
909 As explained above, an external active switch requires three
910 connections, one to the positive battery terminal, one to
911 the flight computer positive input and one to ground. Again,
912 because TeleMini doesn't have any good ground connection,
913 this is not recommended.
916 The positive battery terminal is available on the Right
917 power switch wire, the positive flight computer input is on
918 the left power switch wire. Hook a lead to either of the
919 mounting holes for a ground connection.
924 <title>TeleMini v2.0</title>
928 <imagedata fileref="telemini-v2-top.jpg" width="5.5in" scalefit="1"/>
933 TeleMini v2.0 is 0.8 inches by 1½ inches. It adds more
934 on-board data logging memory, a built-in USB connector and
935 screw terminals for the battery and power switch. The larger
936 board fits in a 24mm coupler. There's also a battery connector
937 for a LiPo battery if you want to use one of those.
940 <title>TeleMini v2.0 Screw Terminals</title>
942 TeleMini v2.0 has two sets of four screw terminals on the end of the
943 board opposite the telemetry antenna. Using the picture
944 above, the top four have connections for the main pyro
945 circuit and an external battery and the bottom four have
946 connections for the apogee pyro circuit and the power
947 switch. Counting from the left, the connections are as follows:
950 <title>TeleMini v2.0 Connections</title>
951 <?dbfo keep-together="always"?>
952 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
953 <colspec align='center' colwidth='*' colname='Pin #'/>
954 <colspec align='center' colwidth='2*' colname='Pin Name'/>
955 <colspec align='left' colwidth='5*' colname='Description'/>
958 <entry align='center'>Terminal #</entry>
959 <entry align='center'>Terminal Name</entry>
960 <entry align='center'>Description</entry>
966 <entry>Main -</entry>
967 <entry>Main pyro channel connection to pyro circuit</entry>
971 <entry>Main +</entry>
972 <entry>Main pyro channel common connection to battery +</entry>
976 <entry>Battery +</entry>
977 <entry>Positive external battery terminal</entry>
981 <entry>Battery -</entry>
982 <entry>Negative external battery terminal</entry>
985 <entry>Bottom 1</entry>
986 <entry>Apogee -</entry>
987 <entry>Apogee pyro channel connection to pyro circuit</entry>
990 <entry>Bottom 2</entry>
991 <entry>Apogee +</entry>
992 <entry>Apogee pyro channel common connection to
996 <entry>Bottom 3</entry>
997 <entry>Switch Output</entry>
998 <entry>Switch connection to flight computer</entry>
1001 <entry>Bottom 4</entry>
1002 <entry>Switch Input</entry>
1003 <entry>Switch connection to positive battery terminal</entry>
1010 <title>Using a Separate Pyro Battery with TeleMini v2.0</title>
1012 As described above, using an external pyro battery involves
1013 connecting the negative battery terminal to the flight
1014 computer ground, connecting the positive battery terminal to
1015 one of the igniter leads and connecting the other igniter
1016 lead to the per-channel pyro circuit connection.
1019 To connect the negative pyro battery terminal to TeleMini
1020 ground, connect it to the negative external battery
1021 connection, top terminal 4.
1024 Connecting the positive battery terminal to the pyro
1025 charges must be done separate from TeleMini v2.0, by soldering
1026 them together or using some other connector.
1029 The other lead from each pyro charge is then inserted into
1030 the appropriate per-pyro channel screw terminal (top
1031 terminal 1 for the Main charge, bottom terminal 1 for the
1036 <title>Using an Active Switch with TeleMini v2.0</title>
1038 As explained above, an external active switch requires three
1039 connections, one to the positive battery terminal, one to
1040 the flight computer positive input and one to ground. Use
1041 the negative external battery connection, top terminal 4 for
1045 The positive battery terminal is available on bottom
1046 terminal 4, the positive flight computer input is on the
1052 <title>EasyMini</title>
1056 <imagedata fileref="easymini-top.jpg" width="5.5in" scalefit="1"/>
1061 EasyMini is built on a 0.8 inch by 1½ inch circuit board. It's
1062 designed to fit in a 24mm coupler tube. The connectors and
1063 screw terminals match TeleMini v2.0, so you can easily swap between
1064 EasyMini and TeleMini.
1067 <title>EasyMini Screw Terminals</title>
1069 EasyMini has two sets of four screw terminals on the end of the
1070 board opposite the telemetry antenna. Using the picture
1071 above, the top four have connections for the main pyro
1072 circuit and an external battery and the bottom four have
1073 connections for the apogee pyro circuit and the power
1074 switch. Counting from the left, the connections are as follows:
1077 <title>EasyMini Connections</title>
1078 <?dbfo keep-together="always"?>
1079 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
1080 <colspec align='center' colwidth='*' colname='Pin #'/>
1081 <colspec align='center' colwidth='2*' colname='Pin Name'/>
1082 <colspec align='left' colwidth='5*' colname='Description'/>
1085 <entry align='center'>Terminal #</entry>
1086 <entry align='center'>Terminal Name</entry>
1087 <entry align='center'>Description</entry>
1092 <entry>Top 1</entry>
1093 <entry>Main -</entry>
1094 <entry>Main pyro channel connection to pyro circuit</entry>
1097 <entry>Top 2</entry>
1098 <entry>Main +</entry>
1099 <entry>Main pyro channel common connection to battery +</entry>
1102 <entry>Top 3</entry>
1103 <entry>Battery +</entry>
1104 <entry>Positive external battery terminal</entry>
1107 <entry>Top 4</entry>
1108 <entry>Battery -</entry>
1109 <entry>Negative external battery terminal</entry>
1112 <entry>Bottom 1</entry>
1113 <entry>Apogee -</entry>
1114 <entry>Apogee pyro channel connection to pyro circuit</entry>
1117 <entry>Bottom 2</entry>
1118 <entry>Apogee +</entry>
1119 <entry>Apogee pyro channel common connection to
1123 <entry>Bottom 3</entry>
1124 <entry>Switch Output</entry>
1125 <entry>Switch connection to flight computer</entry>
1128 <entry>Bottom 4</entry>
1129 <entry>Switch Input</entry>
1130 <entry>Switch connection to positive battery terminal</entry>
1137 <title>Using a Separate Pyro Battery with EasyMini</title>
1139 As described above, using an external pyro battery involves
1140 connecting the negative battery terminal to the flight
1141 computer ground, connecting the positive battery terminal to
1142 one of the igniter leads and connecting the other igniter
1143 lead to the per-channel pyro circuit connection.
1146 To connect the negative pyro battery terminal to TeleMini
1147 ground, connect it to the negative external battery
1148 connection, top terminal 4.
1151 Connecting the positive battery terminal to the pyro
1152 charges must be done separate from EasyMini, by soldering
1153 them together or using some other connector.
1156 The other lead from each pyro charge is then inserted into
1157 the appropriate per-pyro channel screw terminal (top
1158 terminal 1 for the Main charge, bottom terminal 1 for the
1163 <title>Using an Active Switch with EasyMini</title>
1165 As explained above, an external active switch requires three
1166 connections, one to the positive battery terminal, one to
1167 the flight computer positive input and one to ground. Use
1168 the negative external battery connection, top terminal 4 for
1172 The positive battery terminal is available on bottom
1173 terminal 4, the positive flight computer input is on the
1179 <title>TeleMega</title>
1183 <imagedata fileref="telemega-v1.0-top.jpg" width="5.5in" scalefit="1"/>
1188 TeleMega is a 1¼ inch by 3¼ inch circuit board. It was
1189 designed to easily fit in a 38mm coupler. Like TeleMetrum,
1190 TeleMega has an accelerometer and so it must be mounted so that
1191 the board is aligned with the flight axis. It can be mounted
1192 either antenna up or down.
1195 <title>TeleMega Screw Terminals</title>
1197 TeleMega has two sets of nine screw terminals on the end of
1198 the board opposite the telemetry antenna. They are as follows:
1201 <title>TeleMega Screw Terminals</title>
1202 <?dbfo keep-together="always"?>
1203 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
1204 <colspec align='center' colwidth='*' colname='Pin #'/>
1205 <colspec align='center' colwidth='2*' colname='Pin Name'/>
1206 <colspec align='left' colwidth='5*' colname='Description'/>
1209 <entry align='center'>Terminal #</entry>
1210 <entry align='center'>Terminal Name</entry>
1211 <entry align='center'>Description</entry>
1216 <entry>Top 1</entry>
1217 <entry>Switch Input</entry>
1218 <entry>Switch connection to positive battery terminal</entry>
1221 <entry>Top 2</entry>
1222 <entry>Switch Output</entry>
1223 <entry>Switch connection to flight computer</entry>
1226 <entry>Top 3</entry>
1228 <entry>Ground connection for use with external active switch</entry>
1231 <entry>Top 4</entry>
1232 <entry>Main -</entry>
1233 <entry>Main pyro channel connection to pyro circuit</entry>
1236 <entry>Top 5</entry>
1237 <entry>Main +</entry>
1238 <entry>Main pyro channel common connection to battery +</entry>
1241 <entry>Top 6</entry>
1242 <entry>Apogee -</entry>
1243 <entry>Apogee pyro channel connection to pyro circuit</entry>
1246 <entry>Top 7</entry>
1247 <entry>Apogee +</entry>
1248 <entry>Apogee pyro channel common connection to battery +</entry>
1251 <entry>Top 8</entry>
1253 <entry>D pyro channel connection to pyro circuit</entry>
1256 <entry>Top 9</entry>
1258 <entry>D pyro channel common connection to battery +</entry>
1261 <entry>Bottom 1</entry>
1263 <entry>Ground connection for negative pyro battery terminal</entry>
1266 <entry>Bottom 2</entry>
1268 <entry>Positive pyro battery terminal</entry>
1271 <entry>Bottom 3</entry>
1274 Power switch output. Use to connect main battery to
1279 <entry>Bottom 4</entry>
1281 <entry>A pyro channel connection to pyro circuit</entry>
1284 <entry>Bottom 5</entry>
1286 <entry>A pyro channel common connection to battery +</entry>
1289 <entry>Bottom 6</entry>
1291 <entry>B pyro channel connection to pyro circuit</entry>
1294 <entry>Bottom 7</entry>
1296 <entry>B pyro channel common connection to battery +</entry>
1299 <entry>Bottom 8</entry>
1301 <entry>C pyro channel connection to pyro circuit</entry>
1304 <entry>Bottom 9</entry>
1306 <entry>C pyro channel common connection to battery +</entry>
1313 <title>Using a Separate Pyro Battery with TeleMega</title>
1315 TeleMega provides explicit support for an external pyro
1316 battery. All that is required is to remove the jumper
1317 between the lipo terminal (Bottom 3) and the pyro terminal
1318 (Bottom 2). Then hook the negative pyro battery terminal to ground
1319 (Bottom 1) and the positive pyro battery to the pyro battery
1320 input (Bottom 2). You can then use the existing pyro screw
1321 terminals to hook up all of the pyro charges.
1325 <title>Using Only One Battery With TeleMega</title>
1327 Because TeleMega has built-in support for a separate pyro
1328 battery, if you want to fly with just one battery running
1329 both the computer and firing the charges, you need to
1330 connect the flight computer battery to the pyro
1331 circuit. TeleMega has two screw terminals for this—hook a
1332 wire from the Lipo terminal (Bottom 3) to the Pyro terminal
1337 <title>Using an Active Switch with TeleMega</title>
1339 As explained above, an external active switch requires three
1340 connections, one to the positive battery terminal, one to
1341 the flight computer positive input and one to ground.
1344 The positive battery terminal is available on Top terminal
1345 1, the positive flight computer input is on Top terminal
1346 2. Ground is on Top terminal 3.
1351 <title>Flight Data Recording</title>
1353 Each flight computer logs data at 100 samples per second
1354 during ascent and 10 samples per second during descent, except
1355 for TeleMini v1.0, which records ascent at 10 samples per
1356 second and descent at 1 sample per second. Data are logged to
1357 an on-board flash memory part, which can be partitioned into
1358 several equal-sized blocks, one for each flight.
1361 <title>Data Storage on Altus Metrum altimeters</title>
1362 <?dbfo keep-together="always"?>
1363 <tgroup cols='4' align='center' colsep='1' rowsep='1'>
1364 <colspec align='center' colwidth='*' colname='Device'/>
1365 <colspec align='center' colwidth='*' colname='Bytes per sample'/>
1366 <colspec align='center' colwidth='*' colname='Total storage'/>
1367 <colspec align='center' colwidth='*' colname='Minutes of
1371 <entry align='center'>Device</entry>
1372 <entry align='center'>Bytes per Sample</entry>
1373 <entry align='center'>Total Storage</entry>
1374 <entry align='center'>Minutes at Full Rate</entry>
1379 <entry>TeleMetrum v1.0</entry>
1385 <entry>TeleMetrum v1.1 v1.2</entry>
1391 <entry>TeleMetrum v2.0</entry>
1397 <entry>TeleMini v1.0</entry>
1403 <entry>TeleMini v2.0</entry>
1409 <entry>EasyMini</entry>
1415 <entry>TeleMega</entry>
1424 The on-board flash is partitioned into separate flight logs,
1425 each of a fixed maximum size. Increase the maximum size of
1426 each log and you reduce the number of flights that can be
1427 stored. Decrease the size and you can store more flights.
1430 Configuration data is also stored in the flash memory on
1431 TeleMetrum v1.x, TeleMini and EasyMini. This consumes 64kB
1432 of flash space. This configuration space is not available
1433 for storing flight log data. TeleMetrum v2.0 and TeleMega
1434 store configuration data in a bit of eeprom available within
1435 the processor chip, leaving that space available in flash for
1439 To compute the amount of space needed for a single flight, you
1440 can multiply the expected ascent time (in seconds) by 100
1441 times bytes-per-sample, multiply the expected descent time (in
1442 seconds) by 10 times the bytes per sample and add the two
1443 together. That will slightly under-estimate the storage (in
1444 bytes) needed for the flight. For instance, a TeleMetrum v2.0 flight spending
1445 20 seconds in ascent and 150 seconds in descent will take
1446 about (20 * 1600) + (150 * 160) = 56000 bytes of storage. You
1447 could store dozens of these flights in the on-board flash.
1450 The default size allows for several flights on each flight
1451 computer, except for TeleMini v1.0, which only holds data for a
1452 single flight. You can adjust the size.
1455 Altus Metrum flight computers will not overwrite existing
1456 flight data, so be sure to download flight data and erase it
1457 from the flight computer before it fills up. The flight
1458 computer will still successfully control the flight even if it
1459 cannot log data, so the only thing you will lose is the data.
1463 <title>Installation</title>
1465 A typical installation involves attaching
1466 only a suitable battery, a single pole switch for
1467 power on/off, and two pairs of wires connecting e-matches for the
1468 apogee and main ejection charges. All Altus Metrum products are
1469 designed for use with single-cell batteries with 3.7 volts
1470 nominal. TeleMini v2.0 and EasyMini may also be used with other
1471 batteries as long as they supply between 4 and 12 volts.
1474 The battery connectors are a standard 2-pin JST connector and
1475 match batteries sold by Spark Fun. These batteries are
1476 single-cell Lithium Polymer batteries that nominally provide 3.7
1477 volts. Other vendors sell similar batteries for RC aircraft
1478 using mating connectors, however the polarity for those is
1479 generally reversed from the batteries used by Altus Metrum
1480 products. In particular, the Tenergy batteries supplied for use
1481 in Featherweight flight computers are not compatible with Altus
1482 Metrum flight computers or battery chargers. <emphasis>Check
1483 polarity and voltage before connecting any battery not purchased
1484 from Altus Metrum or Spark Fun.</emphasis>
1487 By default, we use the unregulated output of the battery directly
1488 to fire ejection charges. This works marvelously with standard
1489 low-current e-matches like the J-Tek from MJG Technologies, and with
1490 Quest Q2G2 igniters. However, if you want or need to use a separate
1491 pyro battery, check out the “External Pyro Battery” section in this
1492 manual for instructions on how to wire that up. The altimeters are
1493 designed to work with an external pyro battery of no more than 15 volts.
1496 Ejection charges are wired directly to the screw terminal block
1497 at the aft end of the altimeter. You'll need a very small straight
1498 blade screwdriver for these screws, such as you might find in a
1499 jeweler's screwdriver set.
1502 Except for TeleMini v1.0, the flight computers also use the
1503 screw terminal block for the power switch leads. On TeleMini v1.0,
1504 the power switch leads are soldered directly to the board and
1505 can be connected directly to a switch.
1508 For most air-frames, the integrated antennas are more than
1509 adequate. However, if you are installing in a carbon-fiber or
1510 metal electronics bay which is opaque to RF signals, you may need to
1511 use off-board external antennas instead. In this case, you can
1512 replace the stock UHF antenna wire with an edge-launched SMA connector,
1513 and, on TeleMetrum v1, you can unplug the integrated GPS
1514 antenna and select an appropriate off-board GPS antenna with
1515 cable terminating in a U.FL connector.
1520 <title>System Operation</title>
1522 <title>Firmware Modes </title>
1524 The AltOS firmware build for the altimeters has two
1525 fundamental modes, “idle” and “flight”. Which of these modes
1526 the firmware operates in is determined at start up time. For
1527 TeleMetrum and TeleMega, which have accelerometers, the mode is
1528 controlled by the orientation of the
1529 rocket (well, actually the board, of course...) at the time
1530 power is switched on. If the rocket is “nose up”, then
1531 the flight computer assumes it's on a rail or rod being prepared for
1532 launch, so the firmware chooses flight mode. However, if the
1533 rocket is more or less horizontal, the firmware instead enters
1534 idle mode. Since TeleMini v2.0 and EasyMini don't have an
1535 accelerometer we can use to determine orientation, “idle” mode
1536 is selected if the board is connected via USB to a computer,
1537 otherwise the board enters “flight” mode. TeleMini v1.0
1538 selects “idle” mode if it receives a command packet within the
1539 first five seconds of operation.
1542 At power on, the altimeter will beep out the battery voltage
1543 to the nearest tenth of a volt. Each digit is represented by
1544 a sequence of short “dit” beeps, with a pause between
1545 digits. A zero digit is represented with one long “dah”
1546 beep. Then there will be a short pause while the altimeter
1547 completes initialization and self test, and decides which mode
1551 Here's a short summary of all of the modes and the beeping (or
1552 flashing, in the case of TeleMini v1) that accompanies each
1553 mode. In the description of the beeping pattern, “dit” means a
1554 short beep while "dah" means a long beep (three times as
1555 long). “Brap” means a long dissonant tone.
1557 <title>AltOS Modes</title>
1558 <?dbfo keep-together="always"?>
1559 <tgroup cols='4' align='center' colsep='1' rowsep='1'>
1560 <colspec align='center' colwidth='*' colname='Mode Name'/>
1561 <colspec align='center' colwidth='*' colname='Letter'/>
1562 <colspec align='center' colwidth='*' colname='Beeps'/>
1563 <colspec align='center' colwidth='*' colname='Description'/>
1566 <entry>Mode Name</entry>
1567 <entry>Abbreviation</entry>
1568 <entry>Beeps</entry>
1569 <entry>Description</entry>
1574 <entry>Startup</entry>
1576 <entry>battery voltage in decivolts</entry>
1579 Calibrating sensors, detecting orientation.
1586 <entry>dit dit</entry>
1589 Ready to accept commands over USB or radio link.
1596 <entry>dit dah dah dit</entry>
1599 Waiting for launch. Not listening for commands.
1604 <entry>Boost</entry>
1606 <entry>dah dit dit dit</entry>
1609 Accelerating upwards.
1616 <entry>dit dit dah dit</entry>
1619 Decelerating, but moving faster than 200m/s.
1624 <entry>Coast</entry>
1626 <entry>dah dit dah dit</entry>
1629 Decelerating, moving slower than 200m/s
1634 <entry>Drogue</entry>
1636 <entry>dah dit dit</entry>
1639 Descending after apogee. Above main height.
1646 <entry>dah dah</entry>
1649 Descending. Below main height.
1654 <entry>Landed</entry>
1656 <entry>dit dah dit dit</entry>
1659 Stable altitude for at least ten seconds.
1664 <entry>Sensor error</entry>
1666 <entry>dah dit dit dah</entry>
1669 Error detected during sensor calibration.
1678 In flight or “pad” mode, the altimeter engages the flight
1679 state machine, goes into transmit-only mode to send telemetry,
1680 and waits for launch to be detected. Flight mode is indicated
1681 by an “di-dah-dah-dit” (“P” for pad) on the beeper or lights,
1682 followed by beeps or flashes indicating the state of the
1683 pyrotechnic igniter continuity. One beep/flash indicates
1684 apogee continuity, two beeps/flashes indicate main continuity,
1685 three beeps/flashes indicate both apogee and main continuity,
1686 and one longer “brap” sound which is made by rapidly
1687 alternating between two tones indicates no continuity. For a
1688 dual deploy flight, make sure you're getting three beeps or
1689 flashes before launching! For apogee-only or motor eject
1690 flights, do what makes sense.
1693 If idle mode is entered, you will hear an audible “di-dit” or
1694 see two short flashes (“I” for idle), and the flight state
1695 machine is disengaged, thus no ejection charges will fire.
1696 The altimeters also listen for the radio link when in idle
1697 mode for requests sent via TeleDongle. Commands can be issued
1698 in idle mode over either USB or the radio link
1699 equivalently. TeleMini v1.0 only has the radio link. Idle
1700 mode is useful for configuring the altimeter, for extracting
1701 data from the on-board storage chip after flight, and for
1702 ground testing pyro charges.
1705 In “Idle” and “Pad” modes, once the mode indication
1706 beeps/flashes and continuity indication has been sent, if
1707 there is no space available to log the flight in on-board
1708 memory, the flight computer will emit a warbling tone (much
1709 slower than the “no continuity tone”)
1712 Here's a summary of all of the “pad” and “idle” mode indications.
1714 <title>Pad/Idle Indications</title>
1715 <?dbfo keep-together="always"?>
1716 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
1717 <colspec align='center' colwidth='*' colname='Name'/>
1718 <colspec align='center' colwidth='*' colname='Beeps'/>
1719 <colspec align='center' colwidth='*' colname='Description'/>
1723 <entry>Beeps</entry>
1724 <entry>Description</entry>
1729 <entry>Neither</entry>
1733 No continuity detected on either apogee or main
1739 <entry>Apogee</entry>
1743 Continuity detected only on apogee igniter.
1749 <entry>dit dit</entry>
1752 Continuity detected only on main igniter.
1758 <entry>dit dit dit</entry>
1761 Continuity detected on both igniters.
1766 <entry>Storage Full</entry>
1767 <entry>warble</entry>
1770 On-board data logging storage is full. This will
1771 not prevent the flight computer from safely
1772 controlling the flight or transmitting telemetry
1773 signals, but no record of the flight will be
1774 stored in on-board flash.
1783 Once landed, the flight computer will signal that by emitting
1784 the “Landed” sound described above, after which it will beep
1785 out the apogee height (in meters). Each digit is represented
1786 by a sequence of short “dit” beeps, with a pause between
1787 digits. A zero digit is represented with one long “dah”
1788 beep. The flight computer will continue to report landed mode
1789 and beep out the maximum height until turned off.
1792 One “neat trick” of particular value when TeleMetrum or TeleMega are used with
1793 very large air-frames, is that you can power the board up while the
1794 rocket is horizontal, such that it comes up in idle mode. Then you can
1795 raise the air-frame to launch position, and issue a 'reset' command
1796 via TeleDongle over the radio link to cause the altimeter to reboot and
1797 come up in flight mode. This is much safer than standing on the top
1798 step of a rickety step-ladder or hanging off the side of a launch
1799 tower with a screw-driver trying to turn on your avionics before
1800 installing igniters!
1803 TeleMini v1.0 is configured solely via the radio link. Of course, that
1804 means you need to know the TeleMini radio configuration values
1805 or you won't be able to communicate with it. For situations
1806 when you don't have the radio configuration values, TeleMini v1.0
1807 offers an 'emergency recovery' mode. In this mode, TeleMini is
1808 configured as follows:
1812 Sets the radio frequency to 434.550MHz
1817 Sets the radio calibration back to the factory value.
1822 Sets the callsign to N0CALL
1827 Does not go to 'pad' mode after five seconds.
1833 To get into 'emergency recovery' mode, first find the row of
1834 four small holes opposite the switch wiring. Using a short
1835 piece of small gauge wire, connect the outer two holes
1836 together, then power TeleMini up. Once the red LED is lit,
1837 disconnect the wire and the board should signal that it's in
1838 'idle' mode after the initial five second startup period.
1844 TeleMetrum and TeleMega include a complete GPS receiver. A
1845 complete explanation of how GPS works is beyond the scope of
1846 this manual, but the bottom line is that the GPS receiver
1847 needs to lock onto at least four satellites to obtain a solid
1848 3 dimensional position fix and know what time it is.
1851 The flight computers provide backup power to the GPS chip any time a
1852 battery is connected. This allows the receiver to “warm start” on
1853 the launch rail much faster than if every power-on were a GPS
1854 “cold start”. In typical operations, powering up
1855 on the flight line in idle mode while performing final air-frame
1856 preparation will be sufficient to allow the GPS receiver to cold
1857 start and acquire lock. Then the board can be powered down during
1858 RSO review and installation on a launch rod or rail. When the board
1859 is turned back on, the GPS system should lock very quickly, typically
1860 long before igniter installation and return to the flight line are
1865 <title>Controlling An Altimeter Over The Radio Link</title>
1867 One of the unique features of the Altus Metrum system is the
1868 ability to create a two way command link between TeleDongle
1869 and an altimeter using the digital radio transceivers
1870 built into each device. This allows you to interact with the
1871 altimeter from afar, as if it were directly connected to the
1875 Any operation which can be performed with a flight computer can
1876 either be done with the device directly connected to the
1877 computer via the USB cable, or through the radio
1878 link. TeleMini v1.0 doesn't provide a USB connector and so it is
1879 always communicated with over radio. Select the appropriate
1880 TeleDongle device when the list of devices is presented and
1881 AltosUI will interact with an altimeter over the radio link.
1884 One oddity in the current interface is how AltosUI selects the
1885 frequency for radio communications. Instead of providing
1886 an interface to specifically configure the frequency, it uses
1887 whatever frequency was most recently selected for the target
1888 TeleDongle device in Monitor Flight mode. If you haven't ever
1889 used that mode with the TeleDongle in question, select the
1890 Monitor Flight button from the top level UI, and pick the
1891 appropriate TeleDongle device. Once the flight monitoring
1892 window is open, select the desired frequency and then close it
1893 down again. All radio communications will now use that frequency.
1898 Save Flight Data—Recover flight data from the rocket without
1904 Configure altimeter apogee delays, main deploy heights
1905 and additional pyro event conditions
1906 to respond to changing launch conditions. You can also
1907 'reboot' the altimeter. Use this to remotely enable the
1908 flight computer by turning TeleMetrum or TeleMega on in “idle” mode,
1909 then once the air-frame is oriented for launch, you can
1910 reboot the altimeter and have it restart in pad mode
1911 without having to climb the scary ladder.
1916 Fire Igniters—Test your deployment charges without snaking
1917 wires out through holes in the air-frame. Simply assemble the
1918 rocket as if for flight with the apogee and main charges
1919 loaded, then remotely command the altimeter to fire the
1925 Operation over the radio link for configuring an altimeter, ground
1926 testing igniters, and so forth uses the same RF frequencies as flight
1927 telemetry. To configure the desired TeleDongle frequency, select
1928 the monitor flight tab, then use the frequency selector and
1929 close the window before performing other desired radio operations.
1932 The flight computers only enable radio commanding in 'idle' mode.
1933 TeleMetrum and TeleMega use the accelerometer to detect which orientation they
1934 start up in, so make sure you have the flight computer lying horizontally when you turn
1935 it on. Otherwise, it will start in 'pad' mode ready for
1936 flight, and will not be listening for command packets from TeleDongle.
1939 TeleMini listens for a command packet for five seconds after
1940 first being turned on, if it doesn't hear anything, it enters
1941 'pad' mode, ready for flight and will no longer listen for
1942 command packets. The easiest way to connect to TeleMini is to
1943 initiate the command and select the TeleDongle device. At this
1944 point, the TeleDongle will be attempting to communicate with
1945 the TeleMini. Now turn TeleMini on, and it should immediately
1946 start communicating with the TeleDongle and the desired
1947 operation can be performed.
1950 You can monitor the operation of the radio link by watching the
1951 lights on the devices. The red LED will flash each time a packet
1952 is transmitted, while the green LED will light up on TeleDongle when
1953 it is waiting to receive a packet from the altimeter.
1957 <title>Ground Testing </title>
1959 An important aspect of preparing a rocket using electronic deployment
1960 for flight is ground testing the recovery system. Thanks
1961 to the bi-directional radio link central to the Altus Metrum system,
1962 this can be accomplished in a TeleMega, TeleMetrum or TeleMini equipped rocket
1963 with less work than you may be accustomed to with other systems. It
1967 Just prep the rocket for flight, then power up the altimeter
1968 in “idle” mode (placing air-frame horizontal for TeleMetrum or TeleMega, or
1969 selecting the Configure Altimeter tab for TeleMini). This will cause
1970 the firmware to go into “idle” mode, in which the normal flight
1971 state machine is disabled and charges will not fire without
1972 manual command. You can now command the altimeter to fire the apogee
1973 or main charges from a safe distance using your computer and
1974 TeleDongle and the Fire Igniter tab to complete ejection testing.
1978 <title>Radio Link </title>
1980 Our flight computers all incorporate an RF transceiver, but
1981 it's not a full duplex system... each end can only be transmitting or
1982 receiving at any given moment. So we had to decide how to manage the
1986 By design, the altimeter firmware listens for the radio link when
1987 it's in “idle mode”, which
1988 allows us to use the radio link to configure the rocket, do things like
1989 ejection tests, and extract data after a flight without having to
1990 crack open the air-frame. However, when the board is in “flight
1991 mode”, the altimeter only
1992 transmits and doesn't listen at all. That's because we want to put
1993 ultimate priority on event detection and getting telemetry out of
1995 the radio in case the rocket crashes and we aren't able to extract
1999 We don't generally use a 'normal packet radio' mode like APRS
2000 because they're just too inefficient. The GFSK modulation we
2001 use is FSK with the base-band pulses passed through a Gaussian
2002 filter before they go into the modulator to limit the
2003 transmitted bandwidth. When combined with forward error
2004 correction and interleaving, this allows us to have a very
2005 robust 19.2 kilobit data link with only 10-40 milliwatts of
2006 transmit power, a whip antenna in the rocket, and a hand-held
2007 Yagi on the ground. We've had flights to above 21k feet AGL
2008 with great reception, and calculations suggest we should be
2009 good to well over 40k feet AGL with a 5-element yagi on the
2010 ground with our 10mW units and over 100k feet AGL with the
2011 40mW devices. We hope to fly boards to higher altitudes over
2012 time, and would of course appreciate customer feedback on
2013 performance in higher altitude flights!
2019 TeleMetrum v2.0 and TeleMega can send APRS if desired, and the
2020 interval between APRS packets can be configured. As each APRS
2021 packet takes a full second to transmit, we recommend an
2022 interval of at least 5 seconds to avoid consuming too much
2023 battery power or radio channel bandwidth. You can configure
2024 the APRS interval using AltosUI; that process is described in
2025 the Configure Altimeter section of the AltosUI chapter.
2028 AltOS uses the APRS compressed position report data format,
2029 which provides for higher position precision and shorter
2030 packets than the original APRS format. It also includes
2031 altitude data, which is invaluable when tracking rockets. We
2032 haven't found a receiver which doesn't handle compressed
2033 positions, but it's just possible that you have one, so if you
2034 have an older device that can receive the raw packets but
2035 isn't displaying position information, it's possible that this
2039 The APRS packet format includes a comment field that can have
2040 arbitrary text in it. AltOS uses this to send status
2041 information about the flight computer. It sends four fields as
2042 shown in the following table.
2045 <title>Altus Metrum APRS Comments</title>
2046 <?dbfo keep-together="always"?>
2047 <tgroup cols='3' align='center' colsep='1' rowsep='1'>
2048 <colspec align='center' colwidth='*' colname='Field'/>
2049 <colspec align='center' colwidth='*' colname='Example'/>
2050 <colspec align='center' colwidth='4*' colname='Description'/>
2053 <entry align='center'>Field</entry>
2054 <entry align='center'>Example</entry>
2055 <entry align='center'>Description</entry>
2062 <entry>GPS Status U for unlocked, L for locked</entry>
2067 <entry>Number of Satellites in View</entry>
2072 <entry>Altimeter Battery Voltage</entry>
2077 <entry>Apogee Igniter Voltage</entry>
2082 <entry>Main Igniter Voltage</entry>
2088 Here's an example of an APRS comment showing GPS lock with 6
2089 satellites in view, a primary battery at 4.0V, and
2090 apogee and main igniters both at 3.7V.
2096 Make sure your primary battery is above 3.8V, any connected
2097 igniters are above 3.5V and GPS is locked with at least 5 or 6
2098 satellites in view before flying. If GPS is switching between
2099 L and U regularly, then it doesn't have a good lock and you
2100 should wait until it becomes stable.
2103 If the GPS receiver loses lock, the APRS data transmitted will
2104 contain the last position for which GPS lock was
2105 available. You can tell that this has happened by noticing
2106 that the GPS status character switches from 'L' to 'U'. Before
2107 GPS has locked, APRS will transmit zero for latitude,
2108 longitude and altitude.
2112 <title>Configurable Parameters</title>
2114 Configuring an Altus Metrum altimeter for flight is very
2115 simple. Even on our baro-only TeleMini and EasyMini boards,
2116 the use of a Kalman filter means there is no need to set a
2117 “mach delay”. The few configurable parameters can all be set
2118 using AltosUI over USB or or radio link via TeleDongle. Read
2119 the Configure Altimeter section in the AltosUI chapter below
2120 for more information.
2123 <title>Radio Frequency</title>
2125 Altus Metrum boards support radio frequencies in the 70cm
2126 band. By default, the configuration interface provides a
2127 list of 10 “standard” frequencies in 100kHz channels starting at
2128 434.550MHz. However, the firmware supports use of
2129 any 50kHz multiple within the 70cm band. At any given
2130 launch, we highly recommend coordinating when and by whom each
2131 frequency will be used to avoid interference. And of course, both
2132 altimeter and TeleDongle must be configured to the same
2133 frequency to successfully communicate with each other.
2137 <title>Callsign</title>
2139 This sets the callsign used for telemetry, APRS and the
2140 packet link. For telemetry and APRS, this is used to
2141 identify the device. For the packet link, the callsign must
2142 match that configured in AltosUI or the link will not
2143 work. This is to prevent accidental configuration of another
2144 Altus Metrum flight computer operating on the same frequency nearby.
2148 <title>Telemetry/RDF/APRS Enable</title>
2150 You can completely disable the radio while in flight, if
2151 necessary. This doesn't disable the packet link in idle
2156 <title>APRS Interval</title>
2158 This selects how often APRS packets are transmitted. Set
2159 this to zero to disable APRS without also disabling the
2160 regular telemetry and RDF transmissions. As APRS takes a
2161 full second to transmit a single position report, we
2162 recommend sending packets no more than once every 5 seconds.
2166 <title>Apogee Delay</title>
2168 Apogee delay is the number of seconds after the altimeter detects flight
2169 apogee that the drogue charge should be fired. In most cases, this
2170 should be left at the default of 0. However, if you are flying
2171 redundant electronics such as for an L3 certification, you may wish
2172 to set one of your altimeters to a positive delay so that both
2173 primary and backup pyrotechnic charges do not fire simultaneously.
2176 The Altus Metrum apogee detection algorithm fires exactly at
2177 apogee. If you are also flying an altimeter like the
2178 PerfectFlite MAWD, which only supports selecting 0 or 1
2179 seconds of apogee delay, you may wish to set the MAWD to 0
2180 seconds delay and set the TeleMetrum to fire your backup 2
2181 or 3 seconds later to avoid any chance of both charges
2182 firing simultaneously. We've flown several air-frames this
2183 way quite happily, including Keith's successful L3 cert.
2187 <title>Apogee Lockout</title>
2189 Apogee lockout is the number of seconds after boost where
2190 the flight computer will not fire the apogee charge, even if
2191 the rocket appears to be at apogee. This is often called
2192 'Mach Delay', as it is intended to prevent a flight computer
2193 from unintentionally firing apogee charges due to the pressure
2194 spike that occurrs across a mach transition. Altus Metrum
2195 flight computers include a Kalman filter which is not fooled
2196 by this sharp pressure increase, and so this setting should
2197 be left at the default value of zero to disable it.
2201 <title>Main Deployment Altitude</title>
2203 By default, the altimeter will fire the main deployment charge at an
2204 elevation of 250 meters (about 820 feet) above ground. We think this
2205 is a good elevation for most air-frames, but feel free to change this
2206 to suit. In particular, if you are flying two altimeters, you may
2208 deployment elevation for the backup altimeter to be something lower
2209 than the primary so that both pyrotechnic charges don't fire
2214 <title>Maximum Flight Log</title>
2216 Changing this value will set the maximum amount of flight
2217 log storage that an individual flight will use. The
2218 available storage is divided into as many flights of the
2219 specified size as can fit in the available space. You can
2220 download and erase individual flight logs. If you fill up
2221 the available storage, future flights will not get logged
2222 until you erase some of the stored ones.
2225 Even though our flight computers (except TeleMini v1.0) can store
2226 multiple flights, we strongly recommend downloading and saving
2227 flight data after each flight.
2231 <title>Ignite Mode</title>
2233 Instead of firing one charge at apogee and another charge at
2234 a fixed height above the ground, you can configure the
2235 altimeter to fire both at apogee or both during
2236 descent. This was added to support an airframe Bdale designed that
2237 had two altimeters, one in the fin can and one in the nose.
2240 Providing the ability to use both igniters for apogee or
2241 main allows some level of redundancy without needing two
2242 flight computers. In Redundant Apogee or Redundant Main
2243 mode, the two charges will be fired two seconds apart.
2247 <title>Pad Orientation</title>
2249 TeleMetrum and TeleMega measure acceleration along the axis
2250 of the board. Which way the board is oriented affects the
2251 sign of the acceleration value. Instead of trying to guess
2252 which way the board is mounted in the air frame, the
2253 altimeter must be explicitly configured for either Antenna
2254 Up or Antenna Down. The default, Antenna Up, expects the end
2255 of the board connected to the 70cm antenna to be nearest the
2256 nose of the rocket, with the end containing the screw
2257 terminals nearest the tail.
2261 <title>Configurable Pyro Channels</title>
2263 In addition to the usual Apogee and Main pyro channels,
2264 TeleMega has four additional channels that can be configured
2265 to activate when various flight conditions are
2266 satisfied. You can select as many conditions as necessary;
2267 all of them must be met in order to activate the
2268 channel. The conditions available are:
2273 Acceleration away from the ground. Select a value, and
2274 then choose whether acceleration should be above or
2275 below that value. Acceleration is positive upwards, so
2276 accelerating towards the ground would produce negative
2277 numbers. Acceleration during descent is noisy and
2278 inaccurate, so be careful when using it during these
2279 phases of the flight.
2284 Vertical speed. Select a value, and then choose whether
2285 vertical speed should be above or below that
2286 value. Speed is positive upwards, so moving towards the
2287 ground would produce negative numbers. Speed during
2288 descent is a bit noisy and so be careful when using it
2289 during these phases of the flight.
2294 Height. Select a value, and then choose whether the
2295 height above the launch pad should be above or below
2301 Orientation. TeleMega contains a 3-axis gyroscope and
2302 accelerometer which is used to measure the current
2303 angle. Note that this angle is not the change in angle
2304 from the launch pad, but rather absolute relative to
2305 gravity; the 3-axis accelerometer is used to compute the
2306 angle of the rocket on the launch pad and initialize the
2307 system. Because this value is computed by integrating
2308 rate gyros, it gets progressively less accurate as the
2309 flight goes on. It should have an accumulated error of
2310 less than 0.2°/second (after 10 seconds of flight, the
2311 error should be less than 2°).
2314 The usual use of the orientation configuration is to
2315 ensure that the rocket is traveling mostly upwards when
2316 deciding whether to ignite air starts or additional
2317 stages. For that, choose a reasonable maximum angle
2318 (like 20°) and set the motor igniter to require an angle
2319 of less than that value.
2324 Flight Time. Time since boost was detected. Select a
2325 value and choose whether to activate the pyro channel
2326 before or after that amount of time.
2331 Ascending. A simple test saying whether the rocket is
2332 going up or not. This is exactly equivalent to testing
2333 whether the speed is > 0.
2338 Descending. A simple test saying whether the rocket is
2339 going down or not. This is exactly equivalent to testing
2340 whether the speed is < 0.
2345 After Motor. The flight software counts each time the
2346 rocket starts accelerating (presumably due to a motor or
2347 motors igniting). Use this value to count ignitions for
2348 multi-staged or multi-airstart launches.
2353 Delay. This value doesn't perform any checks, instead it
2354 inserts a delay between the time when the other
2355 parameters become true and when the pyro channel is
2361 Flight State. The flight software tracks the flight
2362 through a sequence of states:
2366 Boost. The motor has lit and the rocket is
2367 accelerating upwards.
2372 Fast. The motor has burned out and the rocket is
2373 decelerating, but it is going faster than 200m/s.
2378 Coast. The rocket is still moving upwards and
2379 decelerating, but the speed is less than 200m/s.
2384 Drogue. The rocket has reached apogee and is heading
2385 back down, but is above the configured Main
2391 Main. The rocket is still descending, and is below
2397 Landed. The rocket is no longer moving.
2403 You can select a state to limit when the pyro channel
2404 may activate; note that the check is based on when the
2405 rocket transitions <emphasis>into</emphasis> the state, and so checking for
2406 “greater than Boost” means that the rocket is currently
2407 in boost or some later state.
2410 When a motor burns out, the rocket enters either Fast or
2411 Coast state (depending on how fast it is moving). If the
2412 computer detects upwards acceleration again, it will
2413 move back to Boost state.
2422 <title>AltosUI</title>
2426 <imagedata fileref="altosui.png" width="4.6in"/>
2431 The AltosUI program provides a graphical user interface for
2432 interacting with the Altus Metrum product family. AltosUI can
2433 monitor telemetry data, configure devices and many other
2434 tasks. The primary interface window provides a selection of
2435 buttons, one for each major activity in the system. This chapter
2436 is split into sections, each of which documents one of the tasks
2437 provided from the top-level toolbar.
2440 <title>Monitor Flight</title>
2441 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
2443 Selecting this item brings up a dialog box listing all of the
2444 connected TeleDongle devices. When you choose one of these,
2445 AltosUI will create a window to display telemetry data as
2446 received by the selected TeleDongle device.
2451 <imagedata fileref="device-selection.png" width="3.1in"/>
2456 All telemetry data received are automatically recorded in
2457 suitable log files. The name of the files includes the current
2458 date and rocket serial and flight numbers.
2461 The radio frequency being monitored by the TeleDongle device is
2462 displayed at the top of the window. You can configure the
2463 frequency by clicking on the frequency box and selecting the desired
2464 frequency. AltosUI remembers the last frequency selected for each
2465 TeleDongle and selects that automatically the next time you use
2469 Below the TeleDongle frequency selector, the window contains a few
2470 significant pieces of information about the altimeter providing
2471 the telemetry data stream:
2475 <para>The configured call-sign</para>
2478 <para>The device serial number</para>
2481 <para>The flight number. Each altimeter remembers how many
2487 The rocket flight state. Each flight passes through several
2488 states including Pad, Boost, Fast, Coast, Drogue, Main and
2494 The Received Signal Strength Indicator value. This lets
2495 you know how strong a signal TeleDongle is receiving. The
2496 radio inside TeleDongle operates down to about -99dBm;
2497 weaker signals may not be receivable. The packet link uses
2498 error detection and correction techniques which prevent
2499 incorrect data from being reported.
2504 The age of the displayed data, in seconds since the last
2505 successfully received telemetry packet. In normal operation
2506 this will stay in the low single digits. If the number starts
2507 counting up, then you are no longer receiving data over the radio
2508 link from the flight computer.
2513 Finally, the largest portion of the window contains a set of
2514 tabs, each of which contain some information about the rocket.
2515 They're arranged in 'flight order' so that as the flight
2516 progresses, the selected tab automatically switches to display
2517 data relevant to the current state of the flight. You can select
2518 other tabs at any time. The final 'table' tab displays all of
2519 the raw telemetry values in one place in a spreadsheet-like format.
2522 <title>Launch Pad</title>
2526 <imagedata fileref="launch-pad.png" width="5.5in"/>
2531 The 'Launch Pad' tab shows information used to decide when the
2532 rocket is ready for flight. The first elements include red/green
2533 indicators, if any of these is red, you'll want to evaluate
2534 whether the rocket is ready to launch:
2537 <term>Battery Voltage</term>
2540 This indicates whether the Li-Po battery powering the
2541 flight computer has sufficient charge to last for
2542 the duration of the flight. A value of more than
2543 3.8V is required for a 'GO' status.
2548 <term>Apogee Igniter Voltage</term>
2551 This indicates whether the apogee
2552 igniter has continuity. If the igniter has a low
2553 resistance, then the voltage measured here will be close
2554 to the Li-Po battery voltage. A value greater than 3.2V is
2555 required for a 'GO' status.
2560 <term>Main Igniter Voltage</term>
2563 This indicates whether the main
2564 igniter has continuity. If the igniter has a low
2565 resistance, then the voltage measured here will be close
2566 to the Li-Po battery voltage. A value greater than 3.2V is
2567 required for a 'GO' status.
2572 <term>On-board Data Logging</term>
2575 This indicates whether there is
2576 space remaining on-board to store flight data for the
2577 upcoming flight. If you've downloaded data, but failed
2578 to erase flights, there may not be any space
2579 left. Most of our flight computers can store multiple
2580 flights, depending on the configured maximum flight log
2581 size. TeleMini v1.0 stores only a single flight, so it
2583 downloaded and erased after each flight to capture
2584 data. This only affects on-board flight logging; the
2585 altimeter will still transmit telemetry and fire
2586 ejection charges at the proper times even if the flight
2587 data storage is full.
2592 <term>GPS Locked</term>
2595 For a TeleMetrum or TeleMega device, this indicates whether the GPS receiver is
2596 currently able to compute position information. GPS requires
2597 at least 4 satellites to compute an accurate position.
2602 <term>GPS Ready</term>
2605 For a TeleMetrum or TeleMega device, this indicates whether GPS has reported at least
2606 10 consecutive positions without losing lock. This ensures
2607 that the GPS receiver has reliable reception from the
2615 The Launchpad tab also shows the computed launch pad position
2616 and altitude, averaging many reported positions to improve the
2617 accuracy of the fix.
2621 <title>Ascent</title>
2625 <imagedata fileref="ascent.png" width="5.5in"/>
2630 This tab is shown during Boost, Fast and Coast
2631 phases. The information displayed here helps monitor the
2632 rocket as it heads towards apogee.
2635 The height, speed, acceleration and tilt are shown along
2636 with the maximum values for each of them. This allows you to
2637 quickly answer the most commonly asked questions you'll hear
2641 The current latitude and longitude reported by the GPS are
2642 also shown. Note that under high acceleration, these values
2643 may not get updated as the GPS receiver loses position
2644 fix. Once the rocket starts coasting, the receiver should
2645 start reporting position again.
2648 Finally, the current igniter voltages are reported as in the
2649 Launch Pad tab. This can help diagnose deployment failures
2650 caused by wiring which comes loose under high acceleration.
2654 <title>Descent</title>
2658 <imagedata fileref="descent.png" width="5.5in"/>
2663 Once the rocket has reached apogee and (we hope) activated the
2664 apogee charge, attention switches to tracking the rocket on
2665 the way back to the ground, and for dual-deploy flights,
2666 waiting for the main charge to fire.
2669 To monitor whether the apogee charge operated correctly, the
2670 current descent rate is reported along with the current
2671 height. Good descent rates vary based on the choice of recovery
2672 components, but generally range from 15-30m/s on drogue and should
2673 be below 10m/s when under the main parachute in a dual-deploy flight.
2676 With GPS-equipped flight computers, you can locate the rocket in the
2677 sky using the elevation and bearing information to figure
2678 out where to look. Elevation is in degrees above the
2679 horizon. Bearing is reported in degrees relative to true
2680 north. Range can help figure out how big the rocket will
2681 appear. Ground Distance shows how far it is to a point
2682 directly under the rocket and can help figure out where the
2683 rocket is likely to land. Note that all of these values are
2684 relative to the pad location. If the elevation is near 90°,
2685 the rocket is over the pad, not over you.
2688 Finally, the igniter voltages are reported in this tab as
2689 well, both to monitor the main charge as well as to see what
2690 the status of the apogee charge is. Note that some commercial
2691 e-matches are designed to retain continuity even after being
2692 fired, and will continue to show as green or return from red to
2697 <title>Landed</title>
2701 <imagedata fileref="landed.png" width="5.5in"/>
2706 Once the rocket is on the ground, attention switches to
2707 recovery. While the radio signal is often lost once the
2708 rocket is on the ground, the last reported GPS position is
2709 generally within a short distance of the actual landing location.
2712 The last reported GPS position is reported both by
2713 latitude and longitude as well as a bearing and distance from
2714 the launch pad. The distance should give you a good idea of
2715 whether to walk or hitch a ride. Take the reported
2716 latitude and longitude and enter them into your hand-held GPS
2717 unit and have that compute a track to the landing location.
2720 Our flight computers will continue to transmit RDF
2721 tones after landing, allowing you to locate the rocket by
2722 following the radio signal if necessary. You may need to get
2723 away from the clutter of the flight line, or even get up on
2724 a hill (or your neighbor's RV roof) to receive the RDF signal.
2727 The maximum height, speed and acceleration reported
2728 during the flight are displayed for your admiring observers.
2729 The accuracy of these immediate values depends on the quality
2730 of your radio link and how many packets were received.
2731 Recovering the on-board data after flight may yield
2732 more precise results.
2735 To get more detailed information about the flight, you can
2736 click on the 'Graph Flight' button which will bring up a
2737 graph window for the current flight.
2741 <title>Table</title>
2745 <imagedata fileref="table.png" width="5.5in"/>
2750 The table view shows all of the data available from the
2751 flight computer. Probably the most useful data on
2752 this tab is the detailed GPS information, which includes
2753 horizontal dilution of precision information, and
2754 information about the signal being received from the satellites.
2758 <title>Site Map</title>
2762 <imagedata fileref="site-map.png" width="5.5in"/>
2767 When the TeleMetrum has a GPS fix, the Site Map tab will map
2768 the rocket's position to make it easier for you to locate the
2769 rocket, both while it is in the air, and when it has landed. The
2770 rocket's state is indicated by color: white for pad, red for
2771 boost, pink for fast, yellow for coast, light blue for drogue,
2772 dark blue for main, and black for landed.
2775 The map's scale is approximately 3m (10ft) per pixel. The map
2776 can be dragged using the left mouse button. The map will attempt
2777 to keep the rocket roughly centered while data is being received.
2780 Images are fetched automatically via the Google Maps Static API,
2781 and cached on disk for reuse. If map images cannot be downloaded,
2782 the rocket's path will be traced on a dark gray background
2786 You can pre-load images for your favorite launch sites
2787 before you leave home; check out the 'Preload Maps' section below.
2792 <title>Save Flight Data</title>
2794 The altimeter records flight data to its internal flash memory.
2795 TeleMetrum data is recorded at a much higher rate than the telemetry
2796 system can handle, and is not subject to radio drop-outs. As
2797 such, it provides a more complete and precise record of the
2798 flight. The 'Save Flight Data' button allows you to read the
2799 flash memory and write it to disk.
2802 Clicking on the 'Save Flight Data' button brings up a list of
2803 connected flight computers and TeleDongle devices. If you select a
2804 flight computer, the flight data will be downloaded from that
2805 device directly. If you select a TeleDongle device, flight data
2806 will be downloaded from a flight computer over radio link via the
2807 specified TeleDongle. See the chapter on Controlling An Altimeter
2808 Over The Radio Link for more information.
2811 After the device has been selected, a dialog showing the
2812 flight data saved in the device will be shown allowing you to
2813 select which flights to download and which to delete. With
2814 version 0.9 or newer firmware, you must erase flights in order
2815 for the space they consume to be reused by another
2816 flight. This prevents accidentally losing flight data
2817 if you neglect to download data before flying again. Note that
2818 if there is no more space available in the device, then no
2819 data will be recorded during the next flight.
2822 The file name for each flight log is computed automatically
2823 from the recorded flight date, altimeter serial number and
2824 flight number information.
2828 <title>Replay Flight</title>
2830 Select this button and you are prompted to select a flight
2831 record file, either a .telem file recording telemetry data or a
2832 .eeprom file containing flight data saved from the altimeter
2836 Once a flight record is selected, the flight monitor interface
2837 is displayed and the flight is re-enacted in real time. Check
2838 the Monitor Flight chapter above to learn how this window operates.
2842 <title>Graph Data</title>
2844 Select this button and you are prompted to select a flight
2845 record file, either a .telem file recording telemetry data or a
2846 .eeprom file containing flight data saved from
2850 Note that telemetry files will generally produce poor graphs
2851 due to the lower sampling rate and missed telemetry packets.
2852 Use saved flight data in .eeprom files for graphing where possible.
2855 Once a flight record is selected, a window with multiple tabs is
2859 <title>Flight Graph</title>
2863 <imagedata fileref="graph.png" width="6in" scalefit="1"/>
2868 By default, the graph contains acceleration (blue),
2869 velocity (green) and altitude (red).
2872 The graph can be zoomed into a particular area by clicking and
2873 dragging down and to the right. Once zoomed, the graph can be
2874 reset by clicking and dragging up and to the left. Holding down
2875 control and clicking and dragging allows the graph to be panned.
2876 The right mouse button causes a pop-up menu to be displayed, giving
2877 you the option save or print the plot.
2881 <title>Configure Graph</title>
2885 <imagedata fileref="graph-configure.png" width="6in" scalefit="1"/>
2890 This selects which graph elements to show, and, at the
2891 very bottom, lets you switch between metric and
2896 <title>Flight Statistics</title>
2900 <imagedata fileref="graph-stats.png" width="6in" scalefit="1"/>
2905 Shows overall data computed from the flight.
2913 <imagedata fileref="graph-map.png" width="6in" scalefit="1"/>
2918 Shows a satellite image of the flight area overlaid
2919 with the path of the flight. The red concentric
2920 circles mark the launch pad, the black concentric
2921 circles mark the landing location.
2926 <title>Export Data</title>
2928 This tool takes the raw data files and makes them available for
2929 external analysis. When you select this button, you are prompted to
2930 select a flight data file, which can be either a .eeprom or .telem.
2931 The .eeprom files contain higher resolution and more continuous data,
2932 while .telem files contain receiver signal strength information.
2933 Next, a second dialog appears which is used to select
2934 where to write the resulting file. It has a selector to choose
2935 between CSV and KML file formats.
2938 <title>Comma Separated Value Format</title>
2940 This is a text file containing the data in a form suitable for
2941 import into a spreadsheet or other external data analysis
2942 tool. The first few lines of the file contain the version and
2943 configuration information from the altimeter, then
2944 there is a single header line which labels all of the
2945 fields. All of these lines start with a '#' character which
2946 many tools can be configured to skip over.
2949 The remaining lines of the file contain the data, with each
2950 field separated by a comma and at least one space. All of
2951 the sensor values are converted to standard units, with the
2952 barometric data reported in both pressure, altitude and
2953 height above pad units.
2957 <title>Keyhole Markup Language (for Google Earth)</title>
2959 This is the format used by Google Earth to provide an overlay
2960 within that application. With this, you can use Google Earth to
2961 see the whole flight path in 3D.
2966 <title>Configure Altimeter</title>
2970 <imagedata fileref="configure-altimeter.png" width="3.6in" scalefit="1"/>
2975 Select this button and then select either an altimeter or
2976 TeleDongle Device from the list provided. Selecting a TeleDongle
2977 device will use the radio link to configure a remote altimeter.
2980 The first few lines of the dialog provide information about the
2981 connected device, including the product name,
2982 software version and hardware serial number. Below that are the
2983 individual configuration entries.
2986 At the bottom of the dialog, there are four buttons:
2993 This writes any changes to the
2994 configuration parameter block in flash memory. If you don't
2995 press this button, any changes you make will be lost.
3003 This resets the dialog to the most recently saved values,
3004 erasing any changes you have made.
3012 This reboots the device. Use this to
3013 switch from idle to pad mode by rebooting once the rocket is
3014 oriented for flight, or to confirm changes you think you saved
3023 This closes the dialog. Any unsaved changes will be
3030 The rest of the dialog contains the parameters to be configured.
3033 <title>Main Deploy Altitude</title>
3035 This sets the altitude (above the recorded pad altitude) at
3036 which the 'main' igniter will fire. The drop-down menu shows
3037 some common values, but you can edit the text directly and
3038 choose whatever you like. If the apogee charge fires below
3039 this altitude, then the main charge will fire two seconds
3040 after the apogee charge fires.
3044 <title>Apogee Delay</title>
3046 When flying redundant electronics, it's often important to
3047 ensure that multiple apogee charges don't fire at precisely
3048 the same time, as that can over pressurize the apogee deployment
3049 bay and cause a structural failure of the air-frame. The Apogee
3050 Delay parameter tells the flight computer to fire the apogee
3051 charge a certain number of seconds after apogee has been
3056 <title>Radio Frequency</title>
3058 This configures which of the frequencies to use for both
3059 telemetry and packet command mode. Note that if you set this
3060 value via packet command mode, the TeleDongle frequency will
3061 also be automatically reconfigured to match so that
3062 communication will continue afterwards.
3066 <title>RF Calibration</title>
3068 The radios in every Altus Metrum device are calibrated at the
3069 factory to ensure that they transmit and receive on the
3070 specified frequency. If you need to you can adjust the calibration
3071 by changing this value. Do not do this without understanding what
3072 the value means, read the appendix on calibration and/or the source
3073 code for more information. To change a TeleDongle's calibration,
3074 you must reprogram the unit completely.
3078 <title>Telemetry/RDF/APRS Enable</title>
3080 Enables the radio for transmission during flight. When
3081 disabled, the radio will not transmit anything during flight
3086 <title>APRS Interval</title>
3088 How often to transmit GPS information via APRS (in
3089 seconds). When set to zero, APRS transmission is
3090 disabled. This option is available on TeleMetrum v2 and
3091 TeleMega boards. TeleMetrum v1 boards cannot transmit APRS
3092 packets. Note that a single APRS packet takes nearly a full
3093 second to transmit, so enabling this option will prevent
3094 sending any other telemetry during that time.
3098 <title>Callsign</title>
3100 This sets the call sign included in each telemetry packet. Set this
3101 as needed to conform to your local radio regulations.
3105 <title>Maximum Flight Log Size</title>
3107 This sets the space (in kilobytes) allocated for each flight
3108 log. The available space will be divided into chunks of this
3109 size. A smaller value will allow more flights to be stored,
3110 a larger value will record data from longer flights.
3114 <title>Ignite Mode</title>
3116 TeleMetrum and TeleMini provide two igniter channels as they
3117 were originally designed as dual-deploy flight
3118 computers. This configuration parameter allows the two
3119 channels to be used in different configurations.
3123 <term>Dual Deploy</term>
3126 This is the usual mode of operation; the
3127 'apogee' channel is fired at apogee and the 'main'
3128 channel at the height above ground specified by the
3129 'Main Deploy Altitude' during descent.
3134 <term>Redundant Apogee</term>
3137 This fires both channels at
3138 apogee, the 'apogee' channel first followed after a two second
3139 delay by the 'main' channel.
3144 <term>Redundant Main</term>
3147 This fires both channels at the
3148 height above ground specified by the Main Deploy
3149 Altitude setting during descent. The 'apogee'
3150 channel is fired first, followed after a two second
3151 delay by the 'main' channel.
3158 <title>Pad Orientation</title>
3160 Because they include accelerometers, TeleMetrum and
3161 TeleMega are sensitive to the orientation of the board. By
3162 default, they expect the antenna end to point forward. This
3163 parameter allows that default to be changed, permitting the
3164 board to be mounted with the antenna pointing aft instead.
3168 <term>Antenna Up</term>
3171 In this mode, the antenna end of the
3172 flight computer must point forward, in line with the
3173 expected flight path.
3178 <term>Antenna Down</term>
3181 In this mode, the antenna end of the
3182 flight computer must point aft, in line with the
3183 expected flight path.
3190 <title>Configure Pyro Channels</title>
3194 <imagedata fileref="configure-pyro.png" width="6in" scalefit="1"/>
3199 This opens a separate window to configure the additional
3200 pyro channels available on TeleMega. One column is
3201 presented for each channel. Each row represents a single
3202 parameter, if enabled the parameter must meet the specified
3203 test for the pyro channel to be fired. See the Pyro Channels
3204 section in the System Operation chapter above for a
3205 description of these parameters.
3208 Select conditions and set the related value; the pyro
3209 channel will be activated when <emphasis>all</emphasis> of the
3210 conditions are met. Each pyro channel has a separate set of
3211 configuration values, so you can use different values for
3212 the same condition with different channels.
3215 Once you have selected the appropriate configuration for all
3216 of the necessary pyro channels, you can save the pyro
3217 configuration along with the rest of the flight computer
3218 configuration by pressing the 'Save' button in the main
3219 Configure Flight Computer window.
3224 <title>Configure AltosUI</title>
3228 <imagedata fileref="configure-altosui.png" width="2.4in" scalefit="1"/>
3233 This button presents a dialog so that you can configure the AltosUI global settings.
3236 <title>Voice Settings</title>
3238 AltosUI provides voice announcements during flight so that you
3239 can keep your eyes on the sky and still get information about
3240 the current flight status. However, sometimes you don't want
3247 <para>Turns all voice announcements on and off</para>
3251 <term>Test Voice</term>
3254 Plays a short message allowing you to verify
3255 that the audio system is working and the volume settings
3263 <title>Log Directory</title>
3265 AltosUI logs all telemetry data and saves all TeleMetrum flash
3266 data to this directory. This directory is also used as the
3267 staring point when selecting data files for display or export.
3270 Click on the directory name to bring up a directory choosing
3271 dialog, select a new directory and click 'Select Directory' to
3272 change where AltosUI reads and writes data files.
3276 <title>Callsign</title>
3278 This value is transmitted in each command packet sent from
3279 TeleDongle and received from an altimeter. It is not used in
3280 telemetry mode, as the callsign configured in the altimeter board
3281 is included in all telemetry packets. Configure this
3282 with the AltosUI operators call sign as needed to comply with
3283 your local radio regulations.
3286 Note that to successfully command a flight computer over the radio
3287 (to configure the altimeter, monitor idle, or fire pyro charges),
3288 the callsign configured here must exactly match the callsign
3289 configured in the flight computer. This matching is case
3294 <title>Imperial Units</title>
3296 This switches between metric units (meters) and imperial
3297 units (feet and miles). This affects the display of values
3298 use during flight monitoring, configuration, data graphing
3299 and all of the voice announcements. It does not change the
3300 units used when exporting to CSV files, those are always
3301 produced in metric units.
3305 <title>Font Size</title>
3307 Selects the set of fonts used in the flight monitor
3308 window. Choose between the small, medium and large sets.
3312 <title>Serial Debug</title>
3314 This causes all communication with a connected device to be
3315 dumped to the console from which AltosUI was started. If
3316 you've started it from an icon or menu entry, the output
3317 will simply be discarded. This mode can be useful to debug
3318 various serial communication issues.
3322 <title>Manage Frequencies</title>
3324 This brings up a dialog where you can configure the set of
3325 frequencies shown in the various frequency menus. You can
3326 add as many as you like, or even reconfigure the default
3327 set. Changing this list does not affect the frequency
3328 settings of any devices, it only changes the set of
3329 frequencies shown in the menus.
3334 <title>Configure Groundstation</title>
3338 <imagedata fileref="configure-groundstation.png" width="3.1in" scalefit="1"/>
3343 Select this button and then select a TeleDongle Device from the list provided.
3346 The first few lines of the dialog provide information about the
3347 connected device, including the product name,
3348 software version and hardware serial number. Below that are the
3349 individual configuration entries.
3352 Note that the TeleDongle itself doesn't save any configuration
3353 data, the settings here are recorded on the local machine in
3354 the Java preferences database. Moving the TeleDongle to
3355 another machine, or using a different user account on the same
3356 machine will cause settings made here to have no effect.
3359 At the bottom of the dialog, there are three buttons:
3366 This writes any changes to the
3367 local Java preferences file. If you don't
3368 press this button, any changes you make will be lost.
3376 This resets the dialog to the most recently saved values,
3377 erasing any changes you have made.
3385 This closes the dialog. Any unsaved changes will be
3392 The rest of the dialog contains the parameters to be configured.
3395 <title>Frequency</title>
3397 This configures the frequency to use for both telemetry and
3398 packet command mode. Set this before starting any operation
3399 involving packet command mode so that it will use the right
3400 frequency. Telemetry monitoring mode also provides a menu to
3401 change the frequency, and that menu also sets the same Java
3402 preference value used here.
3406 <title>Radio Calibration</title>
3408 The radios in every Altus Metrum device are calibrated at the
3409 factory to ensure that they transmit and receive on the
3410 specified frequency. To change a TeleDongle's calibration,
3411 you must reprogram the unit completely, so this entry simply
3412 shows the current value and doesn't allow any changes.
3417 <title>Flash Image</title>
3419 This reprograms Altus Metrum devices with new
3420 firmware. TeleMetrum v1.x, TeleDongle, TeleMini and TeleBT are
3421 all reprogrammed by using another similar unit as a
3422 programming dongle (pair programming). TeleMega, TeleMetrum v2
3423 and EasyMini are all programmed directly over their USB ports
3424 (self programming). Please read the directions for flashing
3425 devices in the Updating Device Firmware chapter below.
3429 <title>Fire Igniter</title>
3433 <imagedata fileref="fire-igniter.png" width="1.2in" scalefit="1"/>
3438 This activates the igniter circuits in the flight computer to help
3439 test recovery systems deployment. Because this command can operate
3440 over the Packet Command Link, you can prepare the rocket as
3441 for flight and then test the recovery system without needing
3442 to snake wires inside the air-frame.
3445 Selecting the 'Fire Igniter' button brings up the usual device
3446 selection dialog. Pick the desired device. This brings up another
3447 window which shows the current continuity test status for all
3448 of the pyro channels.
3451 Next, select the desired igniter to fire. This will enable the
3455 Select the 'Arm' button. This enables the 'Fire' button. The
3456 word 'Arm' is replaced by a countdown timer indicating that
3457 you have 10 seconds to press the 'Fire' button or the system
3458 will deactivate, at which point you start over again at
3459 selecting the desired igniter.
3463 <title>Scan Channels</title>
3467 <imagedata fileref="scan-channels.png" width="3.2in" scalefit="1"/>
3472 This listens for telemetry packets on all of the configured
3473 frequencies, displaying information about each device it
3474 receives a packet from. You can select which of the three
3475 telemetry formats should be tried; by default, it only listens
3476 for the standard telemetry packets used in v1.0 and later
3481 <title>Load Maps</title>
3485 <imagedata fileref="load-maps.png" width="5.2in" scalefit="1"/>
3490 Before heading out to a new launch site, you can use this to
3491 load satellite images in case you don't have internet
3492 connectivity at the site. This loads a fairly large area
3493 around the launch site, which should cover any flight you're likely to make.
3496 There's a drop-down menu of launch sites we know about; if
3497 your favorites aren't there, please let us know the lat/lon
3498 and name of the site. The contents of this list are actually
3499 downloaded from our server at run-time, so as new sites are sent
3500 in, they'll get automatically added to this list.
3503 If the launch site isn't in the list, you can manually enter the lat/lon values
3506 Clicking the 'Load Map' button will fetch images from Google
3507 Maps; note that Google limits how many images you can fetch at
3508 once, so if you load more than one launch site, you may get
3509 some gray areas in the map which indicate that Google is tired
3510 of sending data to you. Try again later.
3514 <title>Monitor Idle</title>
3516 This brings up a dialog similar to the Monitor Flight UI,
3517 except it works with the altimeter in “idle” mode by sending
3518 query commands to discover the current state rather than
3519 listening for telemetry packets. Because this uses command
3520 mode, it needs to have the TeleDongle and flight computer
3521 callsigns match exactly. If you can receive telemetry, but
3522 cannot manage to run Monitor Idle, then it's very likely that
3523 your callsigns are different in some way.
3528 <title>AltosDroid</title>
3530 AltosDroid provides the same flight monitoring capabilities as
3531 AltosUI, but runs on Android devices and is designed to connect
3532 to a TeleBT receiver over Bluetooth™. AltosDroid monitors
3533 telemetry data, logging it to internal storage in the Android
3534 device, and presents that data in a UI the same way the 'Monitor
3535 Flight' window does in AltosUI.
3538 This manual will explain how to configure AltosDroid, connect
3539 to TeleBT, operate the flight monitoring interface and describe
3540 what the displayed data means.
3543 <title>Installing AltosDroid</title>
3545 AltosDroid is available from the Google Play store. To install
3546 it on your Android device, open the Google Play Store
3547 application and search for “altosdroid”. Make sure you don't
3548 have a space between “altos” and “droid” or you probably won't
3549 find what you want. That should bring you to the right page
3550 from which you can download and install the application.
3554 <title>Connecting to TeleBT</title>
3556 Press the Android 'Menu' button or soft-key to see the
3557 configuration options available. Select the 'Connect a device'
3558 option and then the 'Scan for devices' entry at the bottom to
3559 look for your TeleBT device. Select your device, and when it
3560 asks for the code, enter '1234'.
3563 Subsequent connections will not require you to enter that
3564 code, and your 'paired' device will appear in the list without
3569 <title>Configuring AltosDroid</title>
3571 The only configuration option available for AltosDroid is
3572 which frequency to listen on. Press the Android 'Menu' button
3573 or soft-key and pick the 'Select radio frequency' entry. That
3574 brings up a menu of pre-set radio frequencies; pick the one
3575 which matches your altimeter.
3579 <title>AltosDroid Flight Monitoring</title>
3581 AltosDroid is designed to mimic the AltosUI flight monitoring
3582 display, providing separate tabs for each stage of your rocket
3583 flight along with a tab containing a map of the local area
3584 with icons marking the current location of the altimeter and
3590 The 'Launch Pad' tab shows information used to decide when the
3591 rocket is ready for flight. The first elements include red/green
3592 indicators, if any of these is red, you'll want to evaluate
3593 whether the rocket is ready to launch:
3596 <term>Battery Voltage</term>
3599 This indicates whether the Li-Po battery
3600 powering the TeleMetrum has sufficient charge to last for
3601 the duration of the flight. A value of more than
3602 3.8V is required for a 'GO' status.
3607 <term>Apogee Igniter Voltage</term>
3610 This indicates whether the apogee
3611 igniter has continuity. If the igniter has a low
3612 resistance, then the voltage measured here will be close
3613 to the Li-Po battery voltage. A value greater than 3.2V is
3614 required for a 'GO' status.
3619 <term>Main Igniter Voltage</term>
3622 This indicates whether the main
3623 igniter has continuity. If the igniter has a low
3624 resistance, then the voltage measured here will be close
3625 to the Li-Po battery voltage. A value greater than 3.2V is
3626 required for a 'GO' status.
3631 <term>On-board Data Logging</term>
3634 This indicates whether there is
3635 space remaining on-board to store flight data for the
3636 upcoming flight. If you've downloaded data, but failed
3637 to erase flights, there may not be any space
3638 left. TeleMetrum can store multiple flights, depending
3639 on the configured maximum flight log size. TeleMini
3640 stores only a single flight, so it will need to be
3641 downloaded and erased after each flight to capture
3642 data. This only affects on-board flight logging; the
3643 altimeter will still transmit telemetry and fire
3644 ejection charges at the proper times.
3649 <term>GPS Locked</term>
3652 For a TeleMetrum or TeleMega device, this indicates whether the GPS receiver is
3653 currently able to compute position information. GPS requires
3654 at least 4 satellites to compute an accurate position.
3659 <term>GPS Ready</term>
3662 For a TeleMetrum or TeleMega device, this indicates whether GPS has reported at least
3663 10 consecutive positions without losing lock. This ensures
3664 that the GPS receiver has reliable reception from the
3672 The Launchpad tab also shows the computed launch pad position
3673 and altitude, averaging many reported positions to improve the
3674 accuracy of the fix.
3679 <title>Downloading Flight Logs</title>
3681 AltosDroid always saves every bit of telemetry data it
3682 receives. To download that to a computer for use with AltosUI,
3683 simply remove the SD card from your Android device, or connect
3684 your device to your computer's USB port and browse the files
3685 on that device. You will find '.telem' files in the TeleMetrum
3686 directory that will work with AltosUI directly.
3691 <title>Using Altus Metrum Products</title>
3693 <title>Being Legal</title>
3695 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
3696 other authorization to legally operate the radio transmitters that are part
3701 <title>In the Rocket</title>
3703 In the rocket itself, you just need a flight computer and
3704 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
3705 850mAh battery weighs less than a 9V alkaline battery, and will
3706 run a TeleMetrum or TeleMega for hours.
3707 A 110mAh battery weighs less than a triple A battery and is a good
3708 choice for use with TeleMini.
3711 By default, we ship flight computers with a simple wire antenna.
3712 If your electronics bay or the air-frame it resides within is made
3713 of carbon fiber, which is opaque to RF signals, you may prefer to
3714 install an SMA connector so that you can run a coaxial cable to an
3715 antenna mounted elsewhere in the rocket. However, note that the
3716 GPS antenna is fixed on all current products, so you really want
3717 to install the flight computer in a bay made of RF-transparent
3718 materials if at all possible.
3722 <title>On the Ground</title>
3724 To receive the data stream from the rocket, you need an antenna and short
3725 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. If possible, use an SMA to BNC
3726 adapter instead of feedline between the antenna feedpoint and
3727 TeleDongle, as this will give you the best performance. The
3728 TeleDongle in turn plugs directly into the USB port on a notebook
3729 computer. Because TeleDongle looks like a simple serial port, your computer
3730 does not require special device drivers... just plug it in.
3733 The GUI tool, AltosUI, is written in Java and runs across
3734 Linux, Mac OS and Windows. There's also a suite of C tools
3735 for Linux which can perform most of the same tasks.
3738 Alternatively, a TeleBT attached with an SMA to BNC adapter at the
3739 feed point of a hand-held yagi used in conjunction with an Android
3740 device running AltosDroid makes an outstanding ground station.
3743 After the flight, you can use the radio link to extract the more detailed data
3744 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
3745 TeleMetrum board directly. Pulling out the data without having to open up
3746 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
3747 battery, so you'll want one of those anyway... the same cable used by lots
3748 of digital cameras and other modern electronic stuff will work fine.
3751 If your rocket lands out of sight, you may enjoy having a hand-held
3752 GPS receiver, so that you can put in a way-point for the last
3753 reported rocket position before touch-down. This makes looking for
3754 your rocket a lot like Geo-Caching... just go to the way-point and
3755 look around starting from there. AltosDroid on an Android device
3756 with GPS receiver works great for this, too!
3759 You may also enjoy having a ham radio “HT” that covers the 70cm band... you
3760 can use that with your antenna to direction-find the rocket on the ground
3761 the same way you can use a Walston or Beeline tracker. This can be handy
3762 if the rocket is hiding in sage brush or a tree, or if the last GPS position
3763 doesn't get you close enough because the rocket dropped into a canyon, or
3764 the wind is blowing it across a dry lake bed, or something like that... Keith
3765 currently uses a Yaesu VX-7R, Bdale has a Baofung UV-5R
3766 which isn't as nice, but was a whole lot cheaper.
3769 So, to recap, on the ground the hardware you'll need includes:
3770 <orderedlist inheritnum='inherit' numeration='arabic'>
3773 an antenna and feed-line or adapter
3788 optionally, a hand-held GPS receiver
3793 optionally, an HT or receiver covering 435 MHz
3799 The best hand-held commercial directional antennas we've found for radio
3800 direction finding rockets are from
3801 <ulink url="http://www.arrowantennas.com/" >
3804 The 440-3 and 440-5 are both good choices for finding a
3805 TeleMetrum- or TeleMini- equipped rocket when used with a suitable
3806 70cm HT. TeleDongle and an SMA to BNC adapter fit perfectly
3807 between the driven element and reflector of Arrow antennas.
3811 <title>Data Analysis</title>
3813 Our software makes it easy to log the data from each flight, both the
3814 telemetry received during the flight itself, and the more
3815 complete data log recorded in the flash memory on the altimeter
3816 board. Once this data is on your computer, our post-flight tools make it
3817 easy to quickly get to the numbers everyone wants, like apogee altitude,
3818 max acceleration, and max velocity. You can also generate and view a
3819 standard set of plots showing the altitude, acceleration, and
3820 velocity of the rocket during flight. And you can even export a TeleMetrum data file
3821 usable with Google Maps and Google Earth for visualizing the flight path
3822 in two or three dimensions!
3825 Our ultimate goal is to emit a set of files for each flight that can be
3826 published as a web page per flight, or just viewed on your local disk with
3831 <title>Future Plans</title>
3833 We've designed a simple GPS based radio tracker called TeleGPS.
3834 If all goes well, we hope to introduce this in the first
3838 We have designed and prototyped several “companion boards” that
3839 can attach to the companion connector on TeleMetrum and TeleMega
3840 flight computers to collect more data, provide more pyro channels,
3841 and so forth. We do not yet know if or when any of these boards
3842 will be produced in enough quantity to sell. If you have specific
3843 interests for data collection or control of events in your rockets
3844 beyond the capabilities of our existing productions, please let
3848 Because all of our work is open, both the hardware designs and the
3849 software, if you have some great idea for an addition to the current
3850 Altus Metrum family, feel free to dive in and help! Or let us know
3851 what you'd like to see that we aren't already working on, and maybe
3852 we'll get excited about it too...
3856 <ulink url="http://altusmetrum.org/">web site</ulink> for more news
3857 and information as our family of products evolves!
3862 <title>Altimeter Installation Recommendations</title>
3864 Building high-power rockets that fly safely is hard enough. Mix
3865 in some sophisticated electronics and a bunch of radio energy
3866 and some creativity and/or compromise may be required. This chapter
3867 contains some suggestions about how to install Altus Metrum
3868 products into a rocket air-frame, including how to safely and
3869 reliably mix a variety of electronics into the same air-frame.
3872 <title>Mounting the Altimeter</title>
3874 The first consideration is to ensure that the altimeter is
3875 securely fastened to the air-frame. For most of our products, we
3876 prefer nylon standoffs and nylon screws; they're good to at least 50G
3877 and cannot cause any electrical issues on the board. Metal screws
3878 and standoffs are fine, too, just be careful to avoid electrical
3879 shorts! For TeleMini v1.0, we usually cut small pieces of 1/16 inch
3881 under the screw holes, and then take 2x56 nylon screws and
3882 screw them through the TeleMini mounting holes, through the
3883 balsa and into the underlying material.
3885 <orderedlist inheritnum='inherit' numeration='arabic'>
3888 Make sure accelerometer-equipped products like TeleMetrum and
3889 TeleMega are aligned precisely along the axis of
3890 acceleration so that the accelerometer can accurately
3891 capture data during the flight.
3896 Watch for any metal touching components on the
3897 board. Shorting out connections on the bottom of the board
3898 can cause the altimeter to fail during flight.
3904 <title>Dealing with the Antenna</title>
3906 The antenna supplied is just a piece of solid, insulated,
3907 wire. If it gets damaged or broken, it can be easily
3908 replaced. It should be kept straight and not cut; bending or
3909 cutting it will change the resonant frequency and/or
3910 impedance, making it a less efficient radiator and thus
3911 reducing the range of the telemetry signal.
3914 Keeping metal away from the antenna will provide better range
3915 and a more even radiation pattern. In most rockets, it's not
3916 entirely possible to isolate the antenna from metal
3917 components; there are often bolts, all-thread and wires from other
3918 electronics to contend with. Just be aware that the more stuff
3919 like this around the antenna, the lower the range.
3922 Make sure the antenna is not inside a tube made or covered
3923 with conducting material. Carbon fiber is the most common
3924 culprit here -- CF is a good conductor and will effectively
3925 shield the antenna, dramatically reducing signal strength and
3926 range. Metallic flake paint is another effective shielding
3927 material which should be avoided around any antennas.
3930 If the ebay is large enough, it can be convenient to simply
3931 mount the altimeter at one end and stretch the antenna out
3932 inside. Taping the antenna to the sled can keep it straight
3933 under acceleration. If there are metal rods, keep the
3934 antenna as far away as possible.
3937 For a shorter ebay, it's quite practical to have the antenna
3938 run through a bulkhead and into an adjacent bay. Drill a small
3939 hole in the bulkhead, pass the antenna wire through it and
3940 then seal it up with glue or clay. We've also used acrylic
3941 tubing to create a cavity for the antenna wire. This works a
3942 bit better in that the antenna is known to stay straight and
3943 not get folded by recovery components in the bay. Angle the
3944 tubing towards the side wall of the rocket and it ends up
3945 consuming very little space.
3948 If you need to place the UHF antenna at a distance from the
3949 altimeter, you can replace the antenna with an edge-mounted
3950 SMA connector, and then run 50Ω coax from the board to the
3951 antenna. Building a remote antenna is beyond the scope of this
3956 <title>Preserving GPS Reception</title>
3958 The GPS antenna and receiver used in TeleMetrum and TeleMega is
3959 highly sensitive and normally have no trouble tracking enough
3960 satellites to provide accurate position information for
3961 recovering the rocket. However, there are many ways the GPS signal
3962 can end up attenuated, negatively affecting GPS performance.
3963 <orderedlist inheritnum='inherit' numeration='arabic'>
3966 Conductive tubing or coatings. Carbon fiber and metal
3967 tubing, or metallic paint will all dramatically attenuate the
3968 GPS signal. We've never heard of anyone successfully
3969 receiving GPS from inside these materials.
3974 Metal components near the GPS patch antenna. These will
3975 de-tune the patch antenna, changing the resonant frequency
3976 away from the L1 carrier and reduce the effectiveness of the
3977 antenna. You can place as much stuff as you like beneath the
3978 antenna as that's covered with a ground plane. But, keep
3979 wires and metal out from above the patch antenna.
3986 <title>Radio Frequency Interference</title>
3988 Any altimeter will generate RFI; the digital circuits use
3989 high-frequency clocks that spray radio interference across a
3990 wide band. Altus Metrum altimeters generate intentional radio
3991 signals as well, increasing the amount of RF energy around the board.
3994 Rocketry altimeters also use precise sensors measuring air
3995 pressure and acceleration. Tiny changes in voltage can cause
3996 these sensor readings to vary by a huge amount. When the
3997 sensors start mis-reporting data, the altimeter can either
3998 fire the igniters at the wrong time, or not fire them at all.
4001 Voltages are induced when radio frequency energy is
4002 transmitted from one circuit to another. Here are things that
4003 influence the induced voltage and current:
4008 Keep wires from different circuits apart. Moving circuits
4009 further apart will reduce RFI.
4014 Avoid parallel wires from different circuits. The longer two
4015 wires run parallel to one another, the larger the amount of
4016 transferred energy. Cross wires at right angles to reduce
4022 Twist wires from the same circuits. Two wires the same
4023 distance from the transmitter will get the same amount of
4024 induced energy which will then cancel out. Any time you have
4025 a wire pair running together, twist the pair together to
4026 even out distances and reduce RFI. For altimeters, this
4027 includes battery leads, switch hookups and igniter
4033 Avoid resonant lengths. Know what frequencies are present
4034 in the environment and avoid having wire lengths near a
4035 natural resonant length. Altus Metrum products transmit on the
4036 70cm amateur band, so you should avoid lengths that are a
4037 simple ratio of that length; essentially any multiple of ¼
4038 of the wavelength (17.5cm).
4044 <title>The Barometric Sensor</title>
4046 Altusmetrum altimeters measure altitude with a barometric
4047 sensor, essentially measuring the amount of air above the
4048 rocket to figure out how high it is. A large number of
4049 measurements are taken as the altimeter initializes itself to
4050 figure out the pad altitude. Subsequent measurements are then
4051 used to compute the height above the pad.
4054 To accurately measure atmospheric pressure, the ebay
4055 containing the altimeter must be vented outside the
4056 air-frame. The vent must be placed in a region of linear
4057 airflow, have smooth edges, and away from areas of increasing or
4058 decreasing pressure.
4061 All barometric sensors are quite sensitive to chemical damage from
4062 the products of APCP or BP combustion, so make sure the ebay is
4063 carefully sealed from any compartment which contains ejection
4068 <title>Ground Testing</title>
4070 The most important aspect of any installation is careful
4071 ground testing. Bringing an air-frame up to the LCO table which
4072 hasn't been ground tested can lead to delays or ejection
4073 charges firing on the pad, or, even worse, a recovery system
4077 Do a 'full systems' test that includes wiring up all igniters
4078 without any BP and turning on all of the electronics in flight
4079 mode. This will catch any mistakes in wiring and any residual
4080 RFI issues that might accidentally fire igniters at the wrong
4081 time. Let the air-frame sit for several minutes, checking for
4082 adequate telemetry signal strength and GPS lock. If any igniters
4083 fire unexpectedly, find and resolve the issue before loading any
4087 Ground test the ejection charges. Prepare the rocket for
4088 flight, loading ejection charges and igniters. Completely
4089 assemble the air-frame and then use the 'Fire Igniters'
4090 interface through a TeleDongle to command each charge to
4091 fire. Make sure the charge is sufficient to robustly separate
4092 the air-frame and deploy the recovery system.
4097 <title>Updating Device Firmware</title>
4099 TeleMega, TeleMetrum v2 and EasyMini are all programmed directly
4100 over their USB connectors (self programming). TeleMetrum v1, TeleMini and
4101 TeleDongle are all programmed by using another device as a
4102 programmer (pair programming). It's important to recognize which
4103 kind of devices you have before trying to reprogram them.
4106 You may wish to begin by ensuring you have current firmware images.
4107 These are distributed as part of the AltOS software bundle that
4108 also includes the AltosUI ground station program. Newer ground
4109 station versions typically work fine with older firmware versions,
4110 so you don't need to update your devices just to try out new
4111 software features. You can always download the most recent
4112 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
4115 If you need to update the firmware on a TeleDongle, we recommend
4116 updating the altimeter first, before updating TeleDongle. However,
4117 note that TeleDongle rarely need to be updated. Any firmware version
4118 1.0.1 or later will work, version 1.2.1 may have improved receiver
4119 performance slightly.
4122 Self-programmable devices (TeleMega, TeleMetrum v2 and EasyMini)
4123 are reprogrammed by connecting them to your computer over USB
4127 Updating TeleMega, TeleMetrum v2 or EasyMini Firmware
4129 <orderedlist inheritnum='inherit' numeration='arabic'>
4132 Attach a battery and power switch to the target
4133 device. Power up the device.
4138 Using a Micro USB cable, connect the target device to your
4139 computer's USB socket.
4144 Run AltosUI, and select 'Flash Image' from the File menu.
4149 Select the target device in the Device Selection dialog.
4154 Select the image you want to flash to the device, which
4155 should have a name in the form
4156 <product>-v<product-version>-<software-version>.ihx, such
4157 as TeleMega-v1.0-1.3.0.ihx.
4162 Make sure the configuration parameters are reasonable
4163 looking. If the serial number and/or RF configuration
4164 values aren't right, you'll need to change them.
4169 Hit the 'OK' button and the software should proceed to flash
4170 the device with new firmware, showing a progress bar.
4175 Verify that the device is working by using the 'Configure
4176 Altimeter' item to check over the configuration.
4181 <title>Recovering From Self-Flashing Failure</title>
4183 If the firmware loading fails, it can leave the device
4184 unable to boot. Not to worry, you can force the device to
4185 start the boot loader instead, which will let you try to
4186 flash the device again.
4189 On each device, connecting two pins from one of the exposed
4190 connectors will force the boot loader to start, even if the
4191 regular operating system has been corrupted in some way.
4195 <term>TeleMega</term>
4198 Connect pin 6 and pin 1 of the companion connector. Pin 1
4199 can be identified by the square pad around it, and then
4200 the pins could sequentially across the board. Be very
4201 careful to <emphasis>not</emphasis> short pin 8 to
4202 anything as that is connected directly to the battery. Pin
4203 7 carries 3.3V and the board will crash if that is
4204 connected to pin 1, but shouldn't damage the board.
4209 <term>TeleMetrum v2</term>
4212 Connect pin 6 and pin 1 of the companion connector. Pin 1
4213 can be identified by the square pad around it, and then
4214 the pins could sequentially across the board. Be very
4215 careful to <emphasis>not</emphasis> short pin 8 to
4216 anything as that is connected directly to the battery. Pin
4217 7 carries 3.3V and the board will crash if that is
4218 connected to pin 1, but shouldn't damage the board.
4223 <term>EasyMini</term>
4226 Connect pin 6 and pin 1 of the debug connector, which is
4227 the six holes next to the beeper. Pin 1 can be identified
4228 by the square pad around it, and then the pins could
4229 sequentially across the board, making Pin 6 the one on the
4230 other end of the row.
4238 <title>Pair Programming</title>
4240 The big concept to understand is that you have to use a
4241 TeleMega, TeleMetrum or TeleDongle as a programmer to update a
4242 pair programmed device. Due to limited memory resources in the
4243 cc1111, we don't support programming directly over USB for these
4248 <title>Updating TeleMetrum v1.x Firmware</title>
4249 <orderedlist inheritnum='inherit' numeration='arabic'>
4252 Find the 'programming cable' that you got as part of the starter
4253 kit, that has a red 8-pin MicroMaTch connector on one end and a
4254 red 4-pin MicroMaTch connector on the other end.
4259 Take the 2 screws out of the TeleDongle case to get access
4260 to the circuit board.
4265 Plug the 8-pin end of the programming cable to the
4266 matching connector on the TeleDongle, and the 4-pin end to the
4267 matching connector on the TeleMetrum.
4268 Note that each MicroMaTch connector has an alignment pin that
4269 goes through a hole in the PC board when you have the cable
4275 Attach a battery to the TeleMetrum board.
4280 Plug the TeleDongle into your computer's USB port, and power
4286 Run AltosUI, and select 'Flash Image' from the File menu.
4291 Pick the TeleDongle device from the list, identifying it as the
4297 Select the image you want put on the TeleMetrum, which should have a
4298 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
4299 in the default directory, if not you may have to poke around
4300 your system to find it.
4305 Make sure the configuration parameters are reasonable
4306 looking. If the serial number and/or RF configuration
4307 values aren't right, you'll need to change them.
4312 Hit the 'OK' button and the software should proceed to flash
4313 the TeleMetrum with new firmware, showing a progress bar.
4318 Confirm that the TeleMetrum board seems to have updated OK, which you
4319 can do by plugging in to it over USB and using a terminal program
4320 to connect to the board and issue the 'v' command to check
4326 If something goes wrong, give it another try.
4332 <title>Updating TeleMini Firmware</title>
4333 <orderedlist inheritnum='inherit' numeration='arabic'>
4336 You'll need a special 'programming cable' to reprogram the
4337 TeleMini. You can make your own using an 8-pin MicroMaTch
4338 connector on one end and a set of four pins on the other.
4343 Take the 2 screws out of the TeleDongle case to get access
4344 to the circuit board.
4349 Plug the 8-pin end of the programming cable to the matching
4350 connector on the TeleDongle, and the 4-pins into the holes
4351 in the TeleMini circuit board. Note that the MicroMaTch
4352 connector has an alignment pin that goes through a hole in
4353 the PC board when you have the cable oriented correctly, and
4354 that pin 1 on the TeleMini board is marked with a square pad
4355 while the other pins have round pads.
4360 Attach a battery to the TeleMini board.
4365 Plug the TeleDongle into your computer's USB port, and power
4371 Run AltosUI, and select 'Flash Image' from the File menu.
4376 Pick the TeleDongle device from the list, identifying it as the
4382 Select the image you want put on the TeleMini, which should have a
4383 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
4384 in the default directory, if not you may have to poke around
4385 your system to find it.
4390 Make sure the configuration parameters are reasonable
4391 looking. If the serial number and/or RF configuration
4392 values aren't right, you'll need to change them.
4397 Hit the 'OK' button and the software should proceed to flash
4398 the TeleMini with new firmware, showing a progress bar.
4403 Confirm that the TeleMini board seems to have updated OK, which you
4404 can do by configuring it over the radio link through the TeleDongle, or
4405 letting it come up in “flight” mode and listening for telemetry.
4410 If something goes wrong, give it another try.
4416 <title>Updating TeleDongle Firmware</title>
4418 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
4419 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
4421 <orderedlist inheritnum='inherit' numeration='arabic'>
4424 Find the 'programming cable' that you got as part of the starter
4425 kit, that has a red 8-pin MicroMaTch connector on one end and a
4426 red 4-pin MicroMaTch connector on the other end.
4431 Find the USB cable that you got as part of the starter kit, and
4432 plug the “mini” end in to the mating connector on TeleMetrum or TeleDongle.
4437 Take the 2 screws out of the TeleDongle case to get access
4438 to the circuit board.
4443 Plug the 8-pin end of the programming cable to the
4444 matching connector on the programmer, and the 4-pin end to the
4445 matching connector on the TeleDongle.
4446 Note that each MicroMaTch connector has an alignment pin that
4447 goes through a hole in the PC board when you have the cable
4453 Attach a battery to the TeleMetrum board if you're using one.
4458 Plug both the programmer and the TeleDongle into your computer's USB
4459 ports, and power up the programmer.
4464 Run AltosUI, and select 'Flash Image' from the File menu.
4469 Pick the programmer device from the list, identifying it as the
4475 Select the image you want put on the TeleDongle, which should have a
4476 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
4477 in the default directory, if not you may have to poke around
4478 your system to find it.
4483 Make sure the configuration parameters are reasonable
4484 looking. If the serial number and/or RF configuration
4485 values aren't right, you'll need to change them. The TeleDongle
4486 serial number is on the “bottom” of the circuit board, and can
4487 usually be read through the translucent blue plastic case without
4488 needing to remove the board from the case.
4493 Hit the 'OK' button and the software should proceed to flash
4494 the TeleDongle with new firmware, showing a progress bar.
4499 Confirm that the TeleDongle board seems to have updated OK, which you
4500 can do by plugging in to it over USB and using a terminal program
4501 to connect to the board and issue the 'v' command to check
4502 the version, etc. Once you're happy, remove the programming cable
4503 and put the cover back on the TeleDongle.
4508 If something goes wrong, give it another try.
4513 Be careful removing the programming cable from the locking 8-pin
4514 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
4515 screwdriver or knife blade to gently pry the locking ears out
4516 slightly to extract the connector. We used a locking connector on
4517 TeleMetrum to help ensure that the cabling to companion boards
4518 used in a rocket don't ever come loose accidentally in flight.
4523 <title>Hardware Specifications</title>
4526 TeleMega Specifications
4531 Recording altimeter for model rocketry.
4536 Supports dual deployment and four auxiliary pyro channels
4537 (a total of 6 events).
4542 70cm 40mW ham-band transceiver for telemetry down-link.
4547 Barometric pressure sensor good to 100k feet MSL.
4552 1-axis high-g accelerometer for motor characterization, capable of
4558 9-axis IMU including integrated 3-axis accelerometer,
4559 3-axis gyroscope and 3-axis magnetometer.
4564 On-board, integrated uBlox Max 7 GPS receiver with 5Hz update rate capability.
4569 On-board 8 Megabyte non-volatile memory for flight data storage.
4574 USB interface for battery charging, configuration, and data recovery.
4579 Fully integrated support for Li-Po rechargeable batteries.
4584 Can use either main system Li-Po or optional separate pyro battery
4590 3.25 x 1.25 inch board designed to fit inside 38mm air-frame coupler tube.
4597 TeleMetrum v2 Specifications
4602 Recording altimeter for model rocketry.
4607 Supports dual deployment (can fire 2 ejection charges).
4612 70cm, 40mW ham-band transceiver for telemetry down-link.
4617 Barometric pressure sensor good to 100k feet MSL.
4622 1-axis high-g accelerometer for motor characterization, capable of
4628 On-board, integrated uBlox Max 7 GPS receiver with 5Hz update rate capability.
4633 On-board 8 Megabyte non-volatile memory for flight data storage.
4638 USB interface for battery charging, configuration, and data recovery.
4643 Fully integrated support for Li-Po rechargeable batteries.
4648 Uses Li-Po to fire e-matches, can be modified to support
4649 optional separate pyro battery if needed.
4654 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
4660 <title>TeleMetrum v1 Specifications</title>
4664 Recording altimeter for model rocketry.
4669 Supports dual deployment (can fire 2 ejection charges).
4674 70cm, 10mW ham-band transceiver for telemetry down-link.
4679 Barometric pressure sensor good to 45k feet MSL.
4684 1-axis high-g accelerometer for motor characterization, capable of
4685 +/- 50g using default part.
4690 On-board, integrated GPS receiver with 5Hz update rate capability.
4695 On-board 1 megabyte non-volatile memory for flight data storage.
4700 USB interface for battery charging, configuration, and data recovery.
4705 Fully integrated support for Li-Po rechargeable batteries.
4710 Uses Li-Po to fire e-matches, can be modified to support
4711 optional separate pyro battery if needed.
4716 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
4723 TeleMini v2.0 Specifications
4728 Recording altimeter for model rocketry.
4733 Supports dual deployment (can fire 2 ejection charges).
4738 70cm, 10mW ham-band transceiver for telemetry down-link.
4743 Barometric pressure sensor good to 100k feet MSL.
4748 On-board 1 megabyte non-volatile memory for flight data storage.
4753 USB interface for configuration, and data recovery.
4758 Support for Li-Po rechargeable batteries (using an
4759 external charger), or any 3.7-15V external battery.
4764 Uses Li-Po to fire e-matches, can be modified to support
4765 optional separate pyro battery if needed.
4770 1.5 x .8 inch board designed to fit inside 24mm air-frame coupler tube.
4777 TeleMini v1.0 Specifications
4782 Recording altimeter for model rocketry.
4787 Supports dual deployment (can fire 2 ejection charges).
4792 70cm, 10mW ham-band transceiver for telemetry down-link.
4797 Barometric pressure sensor good to 45k feet MSL.
4802 On-board 5 kilobyte non-volatile memory for flight data storage.
4807 RF interface for configuration, and data recovery.
4812 Support for Li-Po rechargeable batteries, using an external charger.
4817 Uses Li-Po to fire e-matches, can be modified to support
4818 optional separate pyro battery if needed.
4823 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
4830 EasyMini Specifications
4835 Recording altimeter for model rocketry.
4840 Supports dual deployment (can fire 2 ejection charges).
4845 Barometric pressure sensor good to 100k feet MSL.
4850 On-board 1 megabyte non-volatile memory for flight data storage.
4855 USB interface for configuration, and data recovery.
4860 Support for Li-Po rechargeable batteries (using an
4861 external charger), or any 3.7-15V external battery.
4866 Uses Li-Po to fire e-matches, can be modified to support
4867 optional separate pyro battery if needed.
4872 1.5 x .8 inch board designed to fit inside 24mm air-frame coupler tube.
4881 <emphasis>TeleMetrum seems to shut off when disconnected from the
4882 computer.</emphasis> <?linebreak?>
4883 Make sure the battery is adequately charged. Remember the
4884 unit will pull more power than the USB port can deliver before the
4885 GPS enters “locked” mode. The battery charges best when TeleMetrum
4889 <emphasis>It's impossible to stop the TeleDongle when it's in “p” mode, I have
4890 to unplug the USB cable? </emphasis><?linebreak?>
4891 Make sure you have tried to “escape out” of
4892 this mode. If this doesn't work the reboot procedure for the
4893 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
4894 outgoing buffer IF your “escape out” ('~~') does not work.
4895 At this point using either 'ao-view' (or possibly
4896 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
4900 <emphasis>The amber LED (on the TeleMetrum) lights up when both
4901 battery and USB are connected. Does this mean it's charging?
4902 </emphasis><?linebreak?>
4903 Yes, the yellow LED indicates the charging at the 'regular' rate.
4904 If the led is out but the unit is still plugged into a USB port,
4905 then the battery is being charged at a 'trickle' rate.
4908 <emphasis>There are no “dit-dah-dah-dit” sound or lights like the manual
4909 mentions?</emphasis><?linebreak?>
4910 That's the “pad” mode. Weak batteries might be the problem.
4911 It is also possible that the flight computer is horizontal and the
4913 is instead a “dit-dit” meaning 'idle'. For TeleMini, it's possible that
4914 it received a command packet which would have left it in “pad” mode.
4917 <emphasis>How do I save flight data?</emphasis><?linebreak?>
4918 Live telemetry is written to file(s) whenever AltosUI is connected
4919 to the TeleDongle. The file area defaults to ~/TeleMetrum
4920 but is easily changed using the menus in AltosUI. The files that
4921 are written end in '.telem'. The after-flight
4922 data-dumped files will end in .eeprom and represent continuous data
4923 unlike the .telem files that are subject to losses
4924 along the RF data path.
4925 See the above instructions on what and how to save the eeprom stored
4926 data after physically retrieving your altimeter. Make sure to save
4927 the on-board data after each flight; while the TeleMetrum can store
4928 multiple flights, you never know when you'll lose the altimeter...
4932 <title>Notes for Older Software</title>
4935 Before AltosUI was written, using Altus Metrum devices required
4936 some finesse with the Linux command line. There was a limited
4937 GUI tool, ao-view, which provided functionality similar to the
4938 Monitor Flight window in AltosUI, but everything else was a
4939 fairly 80's experience. This appendix includes documentation for
4940 using that software.
4944 Both TeleMetrum and TeleDongle can be directly communicated
4945 with using USB ports. The first thing you should try after getting
4946 both units plugged into to your computer's USB port(s) is to run
4947 'ao-list' from a terminal-window to see what port-device-name each
4948 device has been assigned by the operating system.
4949 You will need this information to access the devices via their
4950 respective on-board firmware and data using other command line
4951 programs in the AltOS software suite.
4954 TeleMini can be communicated with through a TeleDongle device
4955 over the radio link. When first booted, TeleMini listens for a
4956 TeleDongle device and if it receives a packet, it goes into
4957 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
4958 launched. The easiest way to get it talking is to start the
4959 communication link on the TeleDongle and the power up the
4963 To access the device's firmware for configuration you need a terminal
4964 program such as you would use to talk to a modem. The software
4965 authors prefer using the program 'cu' which comes from the UUCP package
4966 on most Unix-like systems such as Linux. An example command line for
4967 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
4968 indicated from running the
4969 ao-list program. Another reasonable terminal program for Linux is
4970 'cutecom'. The default 'escape'
4971 character used by CU (i.e. the character you use to
4972 issue commands to cu itself instead of sending the command as input
4973 to the connected device) is a '~'. You will need this for use in
4974 only two different ways during normal operations. First is to exit
4975 the program by sending a '~.' which is called a 'escape-disconnect'
4976 and allows you to close-out from 'cu'. The
4977 second use will be outlined later.
4980 All of the Altus Metrum devices share the concept of a two level
4981 command set in their firmware.
4982 The first layer has several single letter commands. Once
4983 you are using 'cu' (or 'cutecom') sending (typing) a '?'
4984 returns a full list of these
4985 commands. The second level are configuration sub-commands accessed
4986 using the 'c' command, for
4987 instance typing 'c?' will give you this second level of commands
4988 (all of which require the
4989 letter 'c' to access). Please note that most configuration options
4990 are stored only in Flash memory; TeleDongle doesn't provide any storage
4991 for these options and so they'll all be lost when you unplug it.
4994 Try setting these configuration ('c' or second level menu) values. A good
4995 place to start is by setting your call sign. By default, the boards
4996 use 'N0CALL' which is cute, but not exactly legal!
4997 Spend a few minutes getting comfortable with the units, their
4998 firmware, and 'cu' (or possibly 'cutecom').
4999 For instance, try to send
5000 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
5001 Verify you can connect and disconnect from the units while in your
5002 terminal program by sending the escape-disconnect mentioned above.
5005 To set the radio frequency, use the 'c R' command to specify the
5006 radio transceiver configuration parameter. This parameter is computed
5007 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
5008 the standard calibration reference frequency, 'S', (normally 434.550MHz):
5012 Round the result to the nearest integer value.
5013 As with all 'c' sub-commands, follow this with a 'c w' to write the
5014 change to the parameter block in the on-board flash on
5015 your altimeter board if you want the change to stay in place across reboots.
5018 To set the apogee delay, use the 'c d' command.
5019 As with all 'c' sub-commands, follow this with a 'c w' to write the
5020 change to the parameter block in the on-board DataFlash chip.
5023 To set the main deployment altitude, use the 'c m' command.
5024 As with all 'c' sub-commands, follow this with a 'c w' to write the
5025 change to the parameter block in the on-board DataFlash chip.
5028 To calibrate the radio frequency, connect the UHF antenna port to a
5029 frequency counter, set the board to 434.550MHz, and use the 'C'
5030 command to generate a CW carrier. Wait for the transmitter temperature
5031 to stabilize and the frequency to settle down.
5032 Then, divide 434.550 MHz by the
5033 measured frequency and multiply by the current radio cal value show
5034 in the 'c s' command. For an unprogrammed board, the default value
5035 is 1186611 for cc1111 based products and 7119667 for cc1120
5036 based products. Take the resulting integer and program it using the 'c f'
5037 command. Testing with the 'C' command again should show a carrier
5038 within a few tens of Hertz of the intended frequency.
5039 As with all 'c' sub-commands, follow this with a 'c w' to write the
5040 change to the configuration memory.
5043 Note that the 'reboot' command, which is very useful on the altimeters,
5044 will likely just cause problems with the dongle. The *correct* way
5045 to reset the dongle is just to unplug and re-plug it.
5048 A fun thing to do at the launch site and something you can do while
5049 learning how to use these units is to play with the radio link access
5050 between an altimeter and the TeleDongle. Be aware that you *must* create
5051 some physical separation between the devices, otherwise the link will
5052 not function due to signal overload in the receivers in each device.
5055 Now might be a good time to take a break and read the rest of this
5056 manual, particularly about the two “modes” that the altimeters
5057 can be placed in. TeleMetrum uses the position of the device when booting
5058 up will determine whether the unit is in “pad” or “idle” mode. TeleMini
5059 enters “idle” mode when it receives a command packet within the first 5 seconds
5060 of being powered up, otherwise it enters “pad” mode.
5063 You can access an altimeter in idle mode from the TeleDongle's USB
5064 connection using the radio link
5065 by issuing a 'p' command to the TeleDongle. Practice connecting and
5066 disconnecting ('~~' while using 'cu') from the altimeter. If
5067 you cannot escape out of the “p” command, (by using a '~~' when in
5068 CU) then it is likely that your kernel has issues. Try a newer version.
5071 Using this radio link allows you to configure the altimeter, test
5072 fire e-matches and igniters from the flight line, check pyro-match
5073 continuity and so forth. You can leave the unit turned on while it
5074 is in 'idle mode' and then place the
5075 rocket vertically on the launch pad, walk away and then issue a
5076 reboot command. The altimeter will reboot and start sending data
5077 having changed to the “pad” mode. If the TeleDongle is not receiving
5078 this data, you can disconnect 'cu' from the TeleDongle using the
5079 procedures mentioned above and THEN connect to the TeleDongle from
5080 inside 'ao-view'. If this doesn't work, disconnect from the
5081 TeleDongle, unplug it, and try again after plugging it back in.
5084 In order to reduce the chance of accidental firing of pyrotechnic
5085 charges, the command to fire a charge is intentionally somewhat
5086 difficult to type, and the built-in help is slightly cryptic to
5087 prevent accidental echoing of characters from the help text back at
5088 the board from firing a charge. The command to fire the apogee
5089 drogue charge is 'i DoIt drogue' and the command to fire the main
5090 charge is 'i DoIt main'.
5093 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
5094 and 'ao-view' will both auditorily announce and visually indicate
5096 Now you can launch knowing that you have a good data path and
5097 good satellite lock for flight data and recovery. Remember
5098 you MUST tell ao-view to connect to the TeleDongle explicitly in
5099 order for ao-view to be able to receive data.
5102 The altimeters provide RDF (radio direction finding) tones on
5103 the pad, during descent and after landing. These can be used to
5104 locate the rocket using a directional antenna; the signal
5105 strength providing an indication of the direction from receiver to rocket.
5108 TeleMetrum also provides GPS tracking data, which can further simplify
5109 locating the rocket once it has landed. (The last good GPS data
5110 received before touch-down will be on the data screen of 'ao-view'.)
5113 Once you have recovered the rocket you can download the eeprom
5114 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
5115 either a USB cable or over the radio link using TeleDongle.
5116 And by following the man page for 'ao-postflight' you can create
5117 various data output reports, graphs, and even KML data to see the
5118 flight trajectory in Google-earth. (Moving the viewing angle making
5119 sure to connect the yellow lines while in Google-earth is the proper
5123 As for ao-view.... some things are in the menu but don't do anything
5124 very useful. The developers have stopped working on ao-view to focus
5125 on a new, cross-platform ground station program. So ao-view may or
5126 may not be updated in the future. Mostly you just use
5127 the Log and Device menus. It has a wonderful display of the incoming
5128 flight data and I am sure you will enjoy what it has to say to you
5129 once you enable the voice output!
5133 <title>Drill Templates</title>
5135 These images, when printed, provide precise templates for the
5136 mounting holes in Altus Metrum flight computers
5139 <title>TeleMega template</title>
5141 TeleMega has overall dimensions of 1.250 x 3.250 inches, and
5142 the mounting holes are sized for use with 4-40 or M3 screws.
5145 <mediaobject id="TeleMegaTemplate">
5147 <imagedata format="SVG" fileref="telemega.svg"
5148 scalefit="0" scale="100" align="center" />
5154 <title>TeleMetrum template</title>
5156 TeleMetrum has overall dimensions of 1.000 x 2.750 inches, and the
5157 mounting holes are sized for use with 4-40 or M3 screws.
5160 <mediaobject id="TeleMetrumTemplate">
5162 <imagedata format="SVG" fileref="telemetrum.svg"
5163 scalefit="0" scale="100" align="center" />
5169 <title>TeleMini v2/EasyMini template</title>
5171 TeleMini v2 and EasyMini have overall dimensions of 0.800 x 1.500 inches, and the
5172 mounting holes are sized for use with 4-40 or M3 screws.
5175 <mediaobject id="MiniTemplate">
5177 <imagedata format="SVG" fileref="easymini.svg"
5178 scalefit="0" scale="100" align="center" />
5184 <title>TeleMini v1 template</title>
5186 TeleMini has overall dimensions of 0.500 x 1.500 inches, and the
5187 mounting holes are sized for use with 2-56 or M2 screws.
5190 <mediaobject id="TeleMiniTemplate">
5192 <imagedata format="SVG" fileref="telemini.svg"
5193 scalefit="0" scale="100" align="center" />
5200 <title>Calibration</title>
5202 There are only two calibrations required for TeleMetrum and
5203 TeleMega, and only one for TeleDongle, TeleMini and EasyMini.
5204 All boards are shipped from the factory pre-calibrated, but
5205 the procedures are documented here in case they are ever
5206 needed. Re-calibration is not supported by AltosUI, you must
5207 connect to the board with a serial terminal program and
5208 interact directly with the on-board command interpreter to
5212 <title>Radio Frequency</title>
5214 The radio frequency is synthesized from a clock based on the
5215 crystal on the board. The actual frequency of this oscillator
5216 must be measured to generate a calibration constant. While our
5218 bandwidth is wide enough to allow boards to communicate even when
5219 their oscillators are not on exactly the same frequency, performance
5220 is best when they are closely matched.
5221 Radio frequency calibration requires a calibrated frequency counter.
5222 Fortunately, once set, the variation in frequency due to aging and
5223 temperature changes is small enough that re-calibration by customers
5224 should generally not be required.
5227 To calibrate the radio frequency, connect the UHF antenna
5228 port to a frequency counter, set the board to 434.550MHz,
5229 and use the 'C' command in the on-board command interpreter
5230 to generate a CW carrier. For USB-enabled boards, this is
5231 best done over USB. For TeleMini v1, note that the only way
5232 to escape the 'C' command is via power cycle since the board
5233 will no longer be listening for commands once it starts
5234 generating a CW carrier.
5237 Wait for the transmitter temperature to stabilize and the frequency
5238 to settle down. Then, divide 434.550 MHz by the
5239 measured frequency and multiply by the current radio cal value show
5240 in the 'c s' command. For an unprogrammed board, the default value
5241 is 1186611. Take the resulting integer and program it using the 'c f'
5242 command. Testing with the 'C' command again should show a carrier
5243 within a few tens of Hertz of the intended frequency.
5244 As with all 'c' sub-commands, follow this with a 'c w' to write the
5245 change to the parameter block in the on-board storage chip.
5248 Note that any time you re-do the radio frequency calibration, the
5249 radio frequency is reset to the default 434.550 Mhz. If you want
5250 to use another frequency, you will have to set that again after
5251 calibration is completed.
5255 <title>TeleMetrum and TeleMega Accelerometers</title>
5257 While barometric sensors are factory-calibrated,
5258 accelerometers are not, and so each must be calibrated once
5259 installed in a flight computer. Explicitly calibrating the
5260 accelerometers also allows us to load any compatible device.
5261 We perform a two-point calibration using gravity.
5264 To calibrate the acceleration sensor, use the 'c a 0' command. You
5265 will be prompted to orient the board vertically with the UHF antenna
5266 up and press a key, then to orient the board vertically with the
5267 UHF antenna down and press a key. Note that the accuracy of this
5268 calibration depends primarily on how perfectly vertical and still
5269 the board is held during the cal process. As with all 'c'
5270 sub-commands, follow this with a 'c w' to write the
5271 change to the parameter block in the on-board DataFlash chip.
5274 The +1g and -1g calibration points are included in each telemetry
5275 frame and are part of the header stored in onboard flash to be
5276 downloaded after flight. We always store and return raw ADC
5277 samples for each sensor... so nothing is permanently “lost” or
5278 “damaged” if the calibration is poor.
5281 In the unlikely event an accel cal goes badly, it is possible
5282 that TeleMetrum or TeleMega may always come up in 'pad mode'
5283 and as such not be listening to either the USB or radio link.
5284 If that happens, there is a special hook in the firmware to
5285 force the board back in to 'idle mode' so you can re-do the
5286 cal. To use this hook, you just need to ground the SPI clock
5287 pin at power-on. This pin is available as pin 2 on the 8-pin
5288 companion connector, and pin 1 is ground. So either
5289 carefully install a fine-gauge wire jumper between the two
5290 pins closest to the index hole end of the 8-pin connector, or
5291 plug in the programming cable to the 8-pin connector and use
5292 a small screwdriver or similar to short the two pins closest
5293 to the index post on the 4-pin end of the programming cable,
5294 and power up the board. It should come up in 'idle mode'
5295 (two beeps), allowing a re-cal.
5300 <title>Release Notes</title>
5302 <title>Version 1.3.2</title>
5304 xmlns:xi="http://www.w3.org/2001/XInclude"
5305 href="release-notes-1.3.2.xsl"
5306 xpointer="xpointer(/article/*)"/>
5309 <title>Version 1.3.1</title>
5311 xmlns:xi="http://www.w3.org/2001/XInclude"
5312 href="release-notes-1.3.1.xsl"
5313 xpointer="xpointer(/article/*)"/>
5316 <title>Version 1.3</title>
5318 xmlns:xi="http://www.w3.org/2001/XInclude"
5319 href="release-notes-1.3.xsl"
5320 xpointer="xpointer(/article/*)"/>
5323 <title>Version 1.2.1</title>
5325 xmlns:xi="http://www.w3.org/2001/XInclude"
5326 href="release-notes-1.2.1.xsl"
5327 xpointer="xpointer(/article/*)"/>
5330 <title>Version 1.2</title>
5332 xmlns:xi="http://www.w3.org/2001/XInclude"
5333 href="release-notes-1.2.xsl"
5334 xpointer="xpointer(/article/*)"/>
5337 <title>Version 1.1.1</title>
5339 xmlns:xi="http://www.w3.org/2001/XInclude"
5340 href="release-notes-1.1.1.xsl"
5341 xpointer="xpointer(/article/*)"/>
5344 <title>Version 1.1</title>
5346 xmlns:xi="http://www.w3.org/2001/XInclude"
5347 href="release-notes-1.1.xsl"
5348 xpointer="xpointer(/article/*)"/>
5351 <title>Version 1.0.1</title>
5353 xmlns:xi="http://www.w3.org/2001/XInclude"
5354 href="release-notes-1.0.1.xsl"
5355 xpointer="xpointer(/article/*)"/>
5358 <title>Version 0.9.2</title>
5360 xmlns:xi="http://www.w3.org/2001/XInclude"
5361 href="release-notes-0.9.2.xsl"
5362 xpointer="xpointer(/article/*)"/>
5365 <title>Version 0.9</title>
5367 xmlns:xi="http://www.w3.org/2001/XInclude"
5368 href="release-notes-0.9.xsl"
5369 xpointer="xpointer(/article/*)"/>
5372 <title>Version 0.8</title>
5374 xmlns:xi="http://www.w3.org/2001/XInclude"
5375 href="release-notes-0.8.xsl"
5376 xpointer="xpointer(/article/*)"/>
5379 <title>Version 0.7.1</title>
5381 xmlns:xi="http://www.w3.org/2001/XInclude"
5382 href="release-notes-0.7.1.xsl"
5383 xpointer="xpointer(/article/*)"/>
5388 <!-- LocalWords: Altusmetrum
projects / fw / altos / blob