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2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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5 <title>The Altus Metrum System</title>
6 <subtitle>An Owner's Manual for Altus Metrum Rocketry Electronics</subtitle>
10 <imagedata fileref="../altosui/altusmetrum.jpg" role="top"/>
14 <firstname>Bdale</firstname>
15 <surname>Garbee</surname>
18 <firstname>Keith</firstname>
19 <surname>Packard</surname>
22 <firstname>Bob</firstname>
23 <surname>Finch</surname>
26 <firstname>Anthony</firstname>
27 <surname>Towns</surname>
31 <holder>Bdale Garbee and Keith Packard</holder>
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</revnumber>
45 <date>12 November 2013</date>
47 Updated for software version 1.3. Version 1.3 adds support
48 for TeleMega, TeleMetrum v2.0, TeleMini v2.0 and EasyMini
49 and fixes bugs in AltosUI and the AltOS firmware.
53 <revnumber>1.2.1</revnumber>
54 <date>21 May 2013</date>
56 Updated for software version 1.2. Version 1.2 adds support
57 for TeleBT and AltosDroid. It also adds a few minor features
58 and fixes bugs in AltosUI and the AltOS firmware.
62 <revnumber>1.2</revnumber>
63 <date>18 April 2013</date>
65 Updated for software version 1.2. Version 1.2 adds support
66 for MicroPeak and the MicroPeak USB interface.
70 <revnumber>1.1.1</revnumber>
71 <date>16 September 2012</date>
73 Updated for software version 1.1.1 Version 1.1.1 fixes a few
74 bugs found in version 1.1.
78 <revnumber>1.1</revnumber>
79 <date>13 September 2012</date>
81 Updated for software version 1.1. Version 1.1 has new
82 features but is otherwise compatible with version 1.0.
86 <revnumber>1.0</revnumber>
87 <date>24 August 2011</date>
89 Updated for software version 1.0. Note that 1.0 represents a
90 telemetry format change, meaning both ends of a link
91 (TeleMetrum/TeleMini and TeleDongle) must be updated or
92 communications will fail.
96 <revnumber>0.9</revnumber>
97 <date>18 January 2011</date>
99 Updated for software version 0.9. Note that 0.9 represents a
100 telemetry format change, meaning both ends of a link (TeleMetrum and
101 TeleDongle) must be updated or communications will fail.
105 <revnumber>0.8</revnumber>
106 <date>24 November 2010</date>
107 <revremark>Updated for software version 0.8 </revremark>
112 <title>Acknowledgments</title>
114 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing “The
115 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
116 Kit” which formed the basis of the original Getting Started chapter
117 in this manual. Bob was one of our first customers for a production
118 TeleMetrum, and his continued enthusiasm and contributions
119 are immensely gratifying and highly appreciated!
122 And thanks to Anthony (AJ) Towns for major contributions including
123 the AltosUI graphing and site map code and associated documentation.
124 Free software means that our customers and friends can become our
125 collaborators, and we certainly appreciate this level of
129 Have fun using these products, and we hope to meet all of you
130 out on the rocket flight line somewhere.
133 NAR #87103, TRA #12201
135 Keith Packard, KD7SQG
136 NAR #88757, TRA #12200
141 <title>Introduction and Overview</title>
143 Welcome to the Altus Metrum community! Our circuits and software reflect
144 our passion for both hobby rocketry and Free Software. We hope their
145 capabilities and performance will delight you in every way, but by
146 releasing all of our hardware and software designs under open licenses,
147 we also hope to empower you to take as active a role in our collective
151 The first device created for our community was TeleMetrum, a dual
152 deploy altimeter with fully integrated GPS and radio telemetry
153 as standard features, and a “companion interface” that will
154 support optional capabilities in the future. The latest version
155 of TeleMetrum, v2.0, has all of the same features but with
156 improved sensors and radio to offer increased performance.
159 Our second device was TeleMini, a dual deploy altimeter with
160 radio telemetry and radio direction finding. The first version
161 of this device was only 13mm by 38mm (½ inch by 1½ inches) and
162 could fit easily in an 18mm air-frame. The latest version, v2.0,
163 includes a beeper, USB data download and extended on-board
164 flight logging, along with an improved barometric sensor.
167 TeleMega is our most sophisticated device, including six pyro
168 channels (four of which are fully programmable), integrated GPS,
169 integrated gyroscopes for staging/air-start inhibit and high
170 performance telemetry.
173 EasyMini is a dual-deploy altimeter with logging and built-in
177 TeleDongle was our first ground station, providing a USB to RF
178 interfaces for communicating with the altimeters. Combined with
179 your choice of antenna and notebook computer, TeleDongle and our
180 associated user interface software form a complete ground
181 station capable of logging and displaying in-flight telemetry,
182 aiding rocket recovery, then processing and archiving flight
183 data for analysis and review.
186 For a slightly more portable ground station experience that also
187 provides direct rocket recovery support, TeleBT offers flight
188 monitoring and data logging using a Bluetooth™ connection between
189 the receiver and an Android device that has the AltosDroid
190 application installed from the Google Play store.
193 More products will be added to the Altus Metrum family over time, and
194 we currently envision that this will be a single, comprehensive manual
195 for the entire product family.
199 <title>Getting Started</title>
201 The first thing to do after you check the inventory of parts in your
202 “starter kit” is to charge the battery.
205 For TeleMetrum and TeleMega, the battery can be charged by plugging it into the
206 corresponding socket of the device and then using the USB
207 cable to plug the flight computer into your computer's USB socket. The
208 on-board circuitry will charge the battery whenever it is plugged
209 in, because the on-off switch does NOT control the
213 On TeleMetrum v1 boards, when the GPS chip is initially
214 searching for satellites, TeleMetrum will consume more current
215 than it pulls from the USB port, so the battery must be
216 attached in order to get satellite lock. Once GPS is locked,
217 the current consumption goes back down enough to enable charging
218 while running. So it's a good idea to fully charge the battery
219 as your first item of business so there is no issue getting and
220 maintaining satellite lock. The yellow charge indicator led
221 will go out when the battery is nearly full and the charger goes
222 to trickle charge. It can take several hours to fully recharge a
223 deeply discharged battery.
226 TeleMetrum v2.0 and TeleMega use a higher power battery charger,
227 allowing them to charge the battery while running the board at
228 maximum power. When the battery is charging, or when the board
229 is consuming a lot of power, the red LED will be lit. When the
230 battery is fully charged, the green LED will be lit. When the
231 battery is damaged or missing, both LEDs will be lit, which
235 The Lithium Polymer TeleMini and EasyMini battery can be charged by
236 disconnecting it from the board and plugging it into a
237 standalone battery charger such as the LipoCharger product
238 included in TeleMini Starter Kits, and connecting that via a USB
239 cable to a laptop or other USB power source.
242 You can also choose to use another battery with TeleMini v2.0
243 and EasyMini, anything supplying between 4 and 12 volts should
244 work fine (like a standard 9V battery), but if you are planning
245 to fire pyro charges, ground testing is required to verify that
246 the battery supplies enough current to fire your chosen e-matches.
249 The other active device in the starter kit is the TeleDongle USB to
250 RF interface. If you plug it in to your Mac or Linux computer it should
251 “just work”, showing up as a serial port device. Windows systems need
252 driver information that is part of the AltOS download to know that the
253 existing USB modem driver will work. We therefore recommend installing
254 our software before plugging in TeleDongle if you are using a Windows
255 computer. If you are using an older version of Linux and are having
256 problems, try moving to a fresher kernel (2.6.33 or newer).
259 Next you should obtain and install the AltOS software. The AltOS
260 distribution includes the AltosUI ground station program, current
262 images for all of the hardware, and a number of standalone
263 utilities that are rarely needed. Pre-built binary packages are
264 available for Linux, Microsoft Windows, and recent MacOSX
265 versions. Full source code and build instructions are also
266 available. The latest version may always be downloaded from
267 <ulink url="http://altusmetrum.org/AltOS"/>.
270 If you're using a TeleBT instead of the TeleDongle, you'll want to
271 install the AltosDroid application from the Google Play store on an
272 Android device. You don't need a data plan to use AltosDroid, but
273 without network access, the Map view will be less useful as it
274 won't contain any map data. You can also use TeleBT connected
275 over USB with your laptop computer; it acts exactly like a
276 TeleDongle. Anywhere this manual talks about TeleDongle, you can
277 also read that as 'and TeleBT when connected via USB'.
281 <title>Handling Precautions</title>
283 All Altus Metrum products are sophisticated electronic devices.
284 When handled gently and properly installed in an air-frame, they
285 will deliver impressive results. However, as with all electronic
286 devices, there are some precautions you must take.
289 The Lithium Polymer rechargeable batteries have an
290 extraordinary power density. This is great because we can fly with
291 much less battery mass than if we used alkaline batteries or previous
292 generation rechargeable batteries... but if they are punctured
293 or their leads are allowed to short, they can and will release their
295 Thus we recommend that you take some care when handling our batteries
296 and consider giving them some extra protection in your air-frame. We
297 often wrap them in suitable scraps of closed-cell packing foam before
298 strapping them down, for example.
301 The barometric sensors used on all of our flight computers are
302 sensitive to sunlight. In normal mounting situations, the baro sensor
303 and all of the other surface mount components
304 are “down” towards whatever the underlying mounting surface is, so
305 this is not normally a problem. Please consider this when designing an
306 installation in an air-frame with a see-through plastic payload bay. It
307 is particularly important to
308 consider this with TeleMini v1.0, both because the baro sensor is on the
309 “top” of the board, and because many model rockets with payload bays
310 use clear plastic for the payload bay! Replacing these with an opaque
311 cardboard tube, painting them, or wrapping them with a layer of masking
312 tape are all reasonable approaches to keep the sensor out of direct
316 The barometric sensor sampling port must be able to “breathe”,
317 both by not being covered by foam or tape or other materials that might
318 directly block the hole on the top of the sensor, and also by having a
319 suitable static vent to outside air.
322 As with all other rocketry electronics, Altus Metrum altimeters must
323 be protected from exposure to corrosive motor exhaust and ejection
328 <title>Altus Metrum Hardware</title>
330 <title>Overview</title>
332 Here's the full set of Altus Metrum products, both in
333 production and retired.
336 <title>Altus Metrum Electronics</title>
337 <?dbfo keep-together="always"?>
338 <tgroup cols='8' align='center' colsep='1' rowsep='1'>
339 <colspec align='center' colwidth='*' colname='Device'/>
340 <colspec align='center' colwidth='*' colname='Barometer'/>
341 <colspec align='center' colwidth='*' colname='Z-axis accelerometer'/>
342 <colspec align='center' colwidth='*' colname='GPS'/>
343 <colspec align='center' colwidth='*' colname='3D sensors'/>
344 <colspec align='center' colwidth='*' colname='Storage'/>
345 <colspec align='center' colwidth='*' colname='RF'/>
346 <colspec align='center' colwidth='*' colname='Battery'/>
349 <entry align='center'>Device</entry>
350 <entry align='center'>Barometer</entry>
351 <entry align='center'>Z-axis accelerometer</entry>
352 <entry align='center'>GPS</entry>
353 <entry align='center'>3D sensors</entry>
354 <entry align='center'>Storage</entry>
355 <entry align='center'>RF Output</entry>
356 <entry align='center'>Battery</entry>
361 <entry>TeleMetrum v1.0</entry>
362 <entry><para>MP3H6115 10km (33k')</para></entry>
363 <entry><para>MMA2202 50g</para></entry>
364 <entry>SkyTraq</entry>
371 <entry>TeleMetrum v1.1</entry>
372 <entry><para>MP3H6115 10km (33k')</para></entry>
373 <entry><para>MMA2202 50g</para></entry>
374 <entry>SkyTraq</entry>
381 <entry>TeleMetrum v1.2</entry>
382 <entry><para>MP3H6115 10km (33k')</para></entry>
383 <entry><para>ADXL78 70g</para></entry>
384 <entry>SkyTraq</entry>
391 <entry>TeleMetrum v2.0</entry>
392 <entry><para>MS5607 30km (100k')</para></entry>
393 <entry><para>MMA6555 102g</para></entry>
394 <entry>uBlox Max-7Q</entry>
401 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
402 <entry><para>MP3H6115 10km (33k')</para></entry>
411 <entry>TeleMini <?linebreak?>v2.0</entry>
412 <entry><para>MS5607 30km (100k')</para></entry>
418 <entry>3.7-12V</entry>
421 <entry>EasyMini <?linebreak?>v1.0</entry>
422 <entry><para>MS5607 30km (100k')</para></entry>
428 <entry>3.7-12V</entry>
431 <entry>TeleMega <?linebreak?>v1.0</entry>
432 <entry><para>MS5607 30km (100k')</para></entry>
433 <entry><para>MMA6555 102g</para></entry>
434 <entry>uBlox Max-7Q</entry>
435 <entry><para>MPU6000 HMC5883</para></entry>
444 <title>Altus Metrum Boards</title>
445 <?dbfo keep-together="always"?>
446 <tgroup cols='6' align='center' colsep='1' rowsep='1'>
447 <colspec align='center' colwidth='*' colname='Device'/>
448 <colspec align='center' colwidth='*' colname='Connectors'/>
449 <colspec align='center' colwidth='*' colname='Screw Terminals'/>
450 <colspec align='center' colwidth='*' colname='Width'/>
451 <colspec align='center' colwidth='*' colname='Length'/>
452 <colspec align='center' colwidth='*' colname='Tube Size'/>
455 <entry align='center'>Device</entry>
456 <entry align='center'>Connectors</entry>
457 <entry align='center'>Screw Terminals</entry>
458 <entry align='center'>Width</entry>
459 <entry align='center'>Length</entry>
460 <entry align='center'>Tube Size</entry>
465 <entry>TeleMetrum</entry>
469 Companion<?linebreak?>
473 <entry><para>Apogee pyro <?linebreak?>Main pyro <?linebreak?>Switch</para></entry>
474 <entry>1 inch (2.54cm)</entry>
475 <entry>2 ¾ inch (6.99cm)</entry>
476 <entry>29mm coupler</entry>
479 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
486 Apogee pyro <?linebreak?>
489 <entry>½ inch (1.27cm)</entry>
490 <entry>1½ inch (3.81cm)</entry>
491 <entry>18mm coupler</entry>
494 <entry>TeleMini <?linebreak?>v2.0</entry>
502 Apogee pyro <?linebreak?>
503 Main pyro <?linebreak?>
504 Battery <?linebreak?>
507 <entry>0.8 inch (2.03cm)</entry>
508 <entry>1½ inch (3.81cm)</entry>
509 <entry>24mm coupler</entry>
512 <entry>EasyMini</entry>
519 Apogee pyro <?linebreak?>
520 Main pyro <?linebreak?>
521 Battery <?linebreak?>
524 <entry>0.8 inch (2.03cm)</entry>
525 <entry>1½ inch (3.81cm)</entry>
526 <entry>24mm coupler</entry>
529 <entry>TeleMega</entry>
533 Companion<?linebreak?>
538 Apogee pyro <?linebreak?>
539 Main pyro<?linebreak?>
540 Pyro A-D<?linebreak?>
544 <entry>1¼ inch (3.18cm)</entry>
545 <entry>3¼ inch (8.26cm)</entry>
546 <entry>38mm coupler</entry>
553 <title>TeleMetrum</title>
556 <imagedata fileref="telemetrum-v1.1-thside.jpg" width="5.5in" scalefit="1"/>
560 TeleMetrum is a 1 inch by 2¾ inch circuit board. It was designed to
561 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
562 small in diameter may require some creativity in mounting and wiring
563 to succeed! The presence of an accelerometer means TeleMetrum should
564 be aligned along the flight axis of the airframe, and by default the ¼
565 wave UHF wire antenna should be on the nose-cone end of the board. The
566 antenna wire is about 7 inches long, and wiring for a power switch and
567 the e-matches for apogee and main ejection charges depart from the
568 fin can end of the board, meaning an ideal “simple” avionics
569 bay for TeleMetrum should have at least 10 inches of interior length.
573 <title>TeleMini</title>
576 <imagedata fileref="telemini-v1-top.jpg" width="5.5in" scalefit="1"/>
580 TeleMini v1.0 is ½ inches by 1½ inches. It was
581 designed to fit inside an 18mm air-frame tube, but using it in
582 a tube that small in diameter may require some creativity in
583 mounting and wiring to succeed! Since there is no
584 accelerometer, TeleMini can be mounted in any convenient
585 orientation. The default ¼ wave UHF wire antenna attached to
586 the center of one end of the board is about 7 inches long. Two
587 wires for the power switch are connected to holes in the
588 middle of the board. Screw terminals for the e-matches for
589 apogee and main ejection charges depart from the other end of
590 the board, meaning an ideal “simple” avionics bay for TeleMini
591 should have at least 9 inches of interior length.
595 <imagedata fileref="telemini-v2-top.jpg" width="5.5in" scalefit="1"/>
599 TeleMini v2.0 is 0.8 inches by 1½ inches. It adds more
600 on-board data logging memory, a built-in USB connector and
601 screw terminals for the battery and power switch. The larger
602 board fits in a 24mm coupler. There's also a battery connector
603 for a LiPo battery if you want to use one of those.
607 <title>EasyMini</title>
610 <imagedata fileref="easymini-top.jpg" width="5.5in" scalefit="1"/>
614 EasyMini is built on a 0.8 inch by 1½ inch circuit board. It's
615 designed to fit in a 24mm coupler tube. The connectors and
616 screw terminals match TeleMini v2.0, so you can easily swap between
617 EasyMini and TeleMini.
621 <title>TeleMega</title>
624 <imagedata fileref="telemega-v1.0-top.jpg" width="5.5in" scalefit="1"/>
628 TeleMega is a 1¼ inch by 3¼ inch circuit board. It was
629 designed to easily fit in a 38mm coupler. Like TeleMetrum,
630 TeleMega has an accelerometer and so it must be mounted so that
631 the board is aligned with the flight axis. It can be mounted
632 either antenna up or down.
636 <title>Flight Data Recording</title>
638 Each flight computer logs data at 100 samples per second
639 during ascent and 10 samples per second during descent, except
640 for TeleMini v1.0, which records ascent at 10 samples per
641 second and descent at 1 sample per second. Data are logged to
642 an on-board flash memory part, which can be partitioned into
643 several equal-sized blocks, one for each flight.
646 <title>Data Storage on Altus Metrum altimeters</title>
647 <?dbfo keep-together="always"?>
648 <tgroup cols='4' align='center' colsep='1' rowsep='1'>
649 <colspec align='center' colwidth='*' colname='Device'/>
650 <colspec align='center' colwidth='*' colname='Bytes per sample'/>
651 <colspec align='center' colwidth='*' colname='Total storage'/>
652 <colspec align='center' colwidth='*' colname='Minutes of
656 <entry align='center'>Device</entry>
657 <entry align='center'>Bytes per Sample</entry>
658 <entry align='center'>Total Storage</entry>
659 <entry align='center'>Minutes at Full Rate</entry>
664 <entry>TeleMetrum v1.0</entry>
670 <entry>TeleMetrum v1.1 v1.2</entry>
676 <entry>TeleMetrum v2.0</entry>
682 <entry>TeleMini v1.0</entry>
688 <entry>TeleMini v2.0</entry>
694 <entry>EasyMini</entry>
700 <entry>TeleMega</entry>
709 The on-board flash is partitioned into separate flight logs,
710 each of a fixed maximum size. Increase the maximum size of
711 each log and you reduce the number of flights that can be
712 stored. Decrease the size and you can store more flights.
715 Configuration data is also stored in the flash memory on
716 TeleMetrum v1.x, TeleMini and EasyMini. This consumes 64kB
717 of flash space. This configuration space is not available
718 for storing flight log data. TeleMetrum v2.0 and TeleMega
719 store configuration data in a bit of eeprom available within
720 the processor chip, leaving that space available in flash for
724 To compute the amount of space needed for a single flight, you
725 can multiply the expected ascent time (in seconds) by 100
726 times bytes-per-sample, multiply the expected descent time (in
727 seconds) by 10 times the bytes per sample and add the two
728 together. That will slightly under-estimate the storage (in
729 bytes) needed for the flight. For instance, a TeleMetrum v2.0 flight spending
730 20 seconds in ascent and 150 seconds in descent will take
731 about (20 * 1600) + (150 * 160) = 56000 bytes of storage. You
732 could store dozens of these flights in the on-board flash.
735 The default size allows for several flights on each flight
736 computer, except for TeleMini v1.0, which only holds data for a
737 single flight. You can adjust the size.
740 Altus Metrum flight computers will not overwrite existing
741 flight data, so be sure to download flight data and erase it
742 from the flight computer before it fills up. The flight
743 computer will still successfully control the flight even if it
744 cannot log data, so the only thing you will lose is the data.
748 <title>Installation</title>
750 A typical installation involves attaching
751 only a suitable battery, a single pole switch for
752 power on/off, and two pairs of wires connecting e-matches for the
753 apogee and main ejection charges. All Altus Metrum products are
754 designed for use with single-cell batteries with 3.7 volts
755 nominal. TeleMini v2.0 and EasyMini may also be used with other
756 batteries as long as they supply between 4 and 12 volts.
759 The battery connectors are a standard 2-pin JST connector and
760 match batteries sold by Spark Fun. These batteries are
761 single-cell Lithium Polymer batteries that nominally provide 3.7
762 volts. Other vendors sell similar batteries for RC aircraft
763 using mating connectors, however the polarity for those is
764 generally reversed from the batteries used by Altus Metrum
765 products. In particular, the Tenergy batteries supplied for use
766 in Featherweight flight computers are not compatible with Altus
767 Metrum flight computers or battery chargers. <emphasis>Check
768 polarity and voltage before connecting any battery not purchased
769 from Altus Metrum or Spark Fun.</emphasis>
772 By default, we use the unregulated output of the battery directly
773 to fire ejection charges. This works marvelously with standard
774 low-current e-matches like the J-Tek from MJG Technologies, and with
775 Quest Q2G2 igniters. However, if you want or need to use a separate
776 pyro battery, check out the “External Pyro Battery” section in this
777 manual for instructions on how to wire that up. The altimeters are
778 designed to work with an external pyro battery of no more than 15 volts.
782 Ejection charges are wired directly to the screw terminal block
783 at the aft end of the altimeter. You'll need a very small straight
784 blade screwdriver for these screws, such as you might find in a
785 jeweler's screwdriver set.
788 Except for TeleMini v1.0, the flight computers also use the
789 screw terminal block for the power switch leads. On TeleMini v1.0,
790 the power switch leads are soldered directly to the board and
791 can be connected directly to a switch.
794 For most air-frames, the integrated antennas are more than
795 adequate. However, if you are installing in a carbon-fiber or
796 metal electronics bay which is opaque to RF signals, you may need to
797 use off-board external antennas instead. In this case, you can
798 replace the stock UHF antenna wire with an edge-launched SMA connector,
799 and, on TeleMetrum v1, you can unplug the integrated GPS
800 antenna and select an appropriate off-board GPS antenna with
801 cable terminating in a U.FL connector.
806 <title>System Operation</title>
808 <title>Firmware Modes </title>
810 The AltOS firmware build for the altimeters has two
811 fundamental modes, “idle” and “flight”. Which of these modes
812 the firmware operates in is determined at start up time. For
813 TeleMetrum and TeleMega, which have accelerometers, the mode is
814 controlled by the orientation of the
815 rocket (well, actually the board, of course...) at the time
816 power is switched on. If the rocket is “nose up”, then
817 the flight computer assumes it's on a rail or rod being prepared for
818 launch, so the firmware chooses flight mode. However, if the
819 rocket is more or less horizontal, the firmware instead enters
820 idle mode. Since TeleMini v2.0 and EasyMini don't have an
821 accelerometer we can use to determine orientation, “idle” mode
822 is selected if the board is connected via USB to a computer,
823 otherwise the board enters “flight” mode. TeleMini v1.0
824 selects “idle” mode if it receives a command packet within the
825 first five seconds of operation.
828 At power on, you will hear three beeps or see three flashes
829 (“S” in Morse code for start up) and then a pause while
830 the altimeter completes initialization and self test, and decides
831 which mode to enter next.
834 In flight or “pad” mode, the altimeter engages the flight
835 state machine, goes into transmit-only mode to
836 send telemetry, and waits for launch to be detected.
837 Flight mode is indicated by an “di-dah-dah-dit” (“P” for pad)
838 on the beeper or lights, followed by beeps or flashes
839 indicating the state of the pyrotechnic igniter continuity.
840 One beep/flash indicates apogee continuity, two beeps/flashes
841 indicate main continuity, three beeps/flashes indicate both
842 apogee and main continuity, and one longer “brap” sound or
843 rapidly alternating lights indicates no continuity. For a
844 dual deploy flight, make sure you're getting three beeps or
845 flashes before launching! For apogee-only or motor eject
846 flights, do what makes sense.
849 If idle mode is entered, you will hear an audible “di-dit” or
850 see two short flashes (“I” for idle), and the flight state
851 machine is disengaged, thus no ejection charges will fire.
852 The altimeters also listen for the radio link when in idle
853 mode for requests sent via TeleDongle. Commands can be issued
854 in idle mode over either USB or the radio link
855 equivalently. TeleMini v1.0 only has the radio link. Idle
856 mode is useful for configuring the altimeter, for extracting
857 data from the on-board storage chip after flight, and for
858 ground testing pyro charges.
861 One “neat trick” of particular value when TeleMetrum or TeleMega are used with
862 very large air-frames, is that you can power the board up while the
863 rocket is horizontal, such that it comes up in idle mode. Then you can
864 raise the air-frame to launch position, and issue a 'reset' command
865 via TeleDongle over the radio link to cause the altimeter to reboot and
866 come up in flight mode. This is much safer than standing on the top
867 step of a rickety step-ladder or hanging off the side of a launch
868 tower with a screw-driver trying to turn on your avionics before
872 TeleMini v1.0 is configured solely via the radio link. Of course, that
873 means you need to know the TeleMini radio configuration values
874 or you won't be able to communicate with it. For situations
875 when you don't have the radio configuration values, TeleMini v1.0
876 offers an 'emergency recovery' mode. In this mode, TeleMini is
877 configured as follows:
881 Sets the radio frequency to 434.550MHz
886 Sets the radio calibration back to the factory value.
891 Sets the callsign to N0CALL
896 Does not go to 'pad' mode after five seconds.
902 To get into 'emergency recovery' mode, first find the row of
903 four small holes opposite the switch wiring. Using a short
904 piece of small gauge wire, connect the outer two holes
905 together, then power TeleMini up. Once the red LED is lit,
906 disconnect the wire and the board should signal that it's in
907 'idle' mode after the initial five second startup period.
913 TeleMetrum and TeleMega include a complete GPS receiver. A
914 complete explanation of how GPS works is beyond the scope of
915 this manual, but the bottom line is that the GPS receiver
916 needs to lock onto at least four satellites to obtain a solid
917 3 dimensional position fix and know what time it is.
920 The flight computers provide backup power to the GPS chip any time a
921 battery is connected. This allows the receiver to “warm start” on
922 the launch rail much faster than if every power-on were a GPS
923 “cold start”. In typical operations, powering up
924 on the flight line in idle mode while performing final air-frame
925 preparation will be sufficient to allow the GPS receiver to cold
926 start and acquire lock. Then the board can be powered down during
927 RSO review and installation on a launch rod or rail. When the board
928 is turned back on, the GPS system should lock very quickly, typically
929 long before igniter installation and return to the flight line are
934 <title>Controlling An Altimeter Over The Radio Link</title>
936 One of the unique features of the Altus Metrum system is the
937 ability to create a two way command link between TeleDongle
938 and an altimeter using the digital radio transceivers
939 built into each device. This allows you to interact with the
940 altimeter from afar, as if it were directly connected to the
944 Any operation which can be performed with a flight computer can
945 either be done with the device directly connected to the
946 computer via the USB cable, or through the radio
947 link. TeleMini v1.0 doesn't provide a USB connector and so it is
948 always communicated with over radio. Select the appropriate
949 TeleDongle device when the list of devices is presented and
950 AltosUI will interact with an altimeter over the radio link.
953 One oddity in the current interface is how AltosUI selects the
954 frequency for radio communications. Instead of providing
955 an interface to specifically configure the frequency, it uses
956 whatever frequency was most recently selected for the target
957 TeleDongle device in Monitor Flight mode. If you haven't ever
958 used that mode with the TeleDongle in question, select the
959 Monitor Flight button from the top level UI, and pick the
960 appropriate TeleDongle device. Once the flight monitoring
961 window is open, select the desired frequency and then close it
962 down again. All radio communications will now use that frequency.
967 Save Flight Data—Recover flight data from the rocket without
973 Configure altimeter apogee delays, main deploy heights
974 and additional pyro event conditions
975 to respond to changing launch conditions. You can also
976 'reboot' the altimeter. Use this to remotely enable the
977 flight computer by turning TeleMetrum or TeleMega on in “idle” mode,
978 then once the air-frame is oriented for launch, you can
979 reboot the altimeter and have it restart in pad mode
980 without having to climb the scary ladder.
985 Fire Igniters—Test your deployment charges without snaking
986 wires out through holes in the air-frame. Simply assemble the
987 rocket as if for flight with the apogee and main charges
988 loaded, then remotely command the altimeter to fire the
994 Operation over the radio link for configuring an altimeter, ground
995 testing igniters, and so forth uses the same RF frequencies as flight
996 telemetry. To configure the desired TeleDongle frequency, select
997 the monitor flight tab, then use the frequency selector and
998 close the window before performing other desired radio operations.
1001 The flight computers only enable radio commanding in 'idle' mode.
1002 TeleMetrum and TeleMega use the accelerometer to detect which orientation they
1003 start up in, so make sure you have the flight computer lying horizontally when you turn
1004 it on. Otherwise, it will start in 'pad' mode ready for
1005 flight, and will not be listening for command packets from TeleDongle.
1008 TeleMini listens for a command packet for five seconds after
1009 first being turned on, if it doesn't hear anything, it enters
1010 'pad' mode, ready for flight and will no longer listen for
1011 command packets. The easiest way to connect to TeleMini is to
1012 initiate the command and select the TeleDongle device. At this
1013 point, the TeleDongle will be attempting to communicate with
1014 the TeleMini. Now turn TeleMini on, and it should immediately
1015 start communicating with the TeleDongle and the desired
1016 operation can be performed.
1019 You can monitor the operation of the radio link by watching the
1020 lights on the devices. The red LED will flash each time a packet
1021 is transmitted, while the green LED will light up on TeleDongle when
1022 it is waiting to receive a packet from the altimeter.
1026 <title>Ground Testing </title>
1028 An important aspect of preparing a rocket using electronic deployment
1029 for flight is ground testing the recovery system. Thanks
1030 to the bi-directional radio link central to the Altus Metrum system,
1031 this can be accomplished in a TeleMega, TeleMetrum or TeleMini equipped rocket
1032 with less work than you may be accustomed to with other systems. It
1036 Just prep the rocket for flight, then power up the altimeter
1037 in “idle” mode (placing air-frame horizontal for TeleMetrum or TeleMega, or
1038 selecting the Configure Altimeter tab for TeleMini). This will cause
1039 the firmware to go into “idle” mode, in which the normal flight
1040 state machine is disabled and charges will not fire without
1041 manual command. You can now command the altimeter to fire the apogee
1042 or main charges from a safe distance using your computer and
1043 TeleDongle and the Fire Igniter tab to complete ejection testing.
1047 <title>Radio Link </title>
1049 Our flight computers all incorporate an RF transceiver, but
1050 it's not a full duplex system... each end can only be transmitting or
1051 receiving at any given moment. So we had to decide how to manage the
1055 By design, the altimeter firmware listens for the radio link when
1056 it's in “idle mode”, which
1057 allows us to use the radio link to configure the rocket, do things like
1058 ejection tests, and extract data after a flight without having to
1059 crack open the air-frame. However, when the board is in “flight
1060 mode”, the altimeter only
1061 transmits and doesn't listen at all. That's because we want to put
1062 ultimate priority on event detection and getting telemetry out of
1064 the radio in case the rocket crashes and we aren't able to extract
1068 We don't generally use a 'normal packet radio' mode like APRS
1069 because they're just too inefficient. The GFSK modulation we
1070 use is FSK with the base-band pulses passed through a Gaussian
1071 filter before they go into the modulator to limit the
1072 transmitted bandwidth. When combined with forward error
1073 correction and interleaving, this allows us to have a very
1074 robust 19.2 kilobit data link with only 10-40 milliwatts of
1075 transmit power, a whip antenna in the rocket, and a hand-held
1076 Yagi on the ground. We've had flights to above 21k feet AGL
1077 with great reception, and calculations suggest we should be
1078 good to well over 40k feet AGL with a 5-element yagi on the
1079 ground with our 10mW units and over 100k feet AGL with the
1080 40mW devices. We hope to fly boards to higher altitudes over
1081 time, and would of course appreciate customer feedback on
1082 performance in higher altitude flights!
1085 TeleMetrum v2.0 and TeleMega can send APRS if desired, and the
1086 interval between APRS packets can be configured. As each APRS
1087 packet takes a full second to transmit, we recommend an
1088 interval of at least 5 seconds to avoid consuming too much
1089 battery power or radio channel bandwidth.
1093 <title>Configurable Parameters</title>
1095 Configuring an Altus Metrum altimeter for flight is very
1096 simple. Even on our baro-only TeleMini and EasyMini boards, the use of a Kalman
1097 filter means there is no need to set a “mach delay”. The few
1098 configurable parameters can all be set using AltosUI over USB or
1099 or radio link via TeleDongle.
1102 <title>Radio Frequency</title>
1104 Altus Metrum boards support radio frequencies in the 70cm
1105 band. By default, the configuration interface provides a
1106 list of 10 “standard” frequencies in 100kHz channels starting at
1107 434.550MHz. However, the firmware supports use of
1108 any 50kHz multiple within the 70cm band. At any given
1109 launch, we highly recommend coordinating when and by whom each
1110 frequency will be used to avoid interference. And of course, both
1111 altimeter and TeleDongle must be configured to the same
1112 frequency to successfully communicate with each other.
1116 <title>Apogee Delay</title>
1118 Apogee delay is the number of seconds after the altimeter detects flight
1119 apogee that the drogue charge should be fired. In most cases, this
1120 should be left at the default of 0. However, if you are flying
1121 redundant electronics such as for an L3 certification, you may wish
1122 to set one of your altimeters to a positive delay so that both
1123 primary and backup pyrotechnic charges do not fire simultaneously.
1126 The Altus Metrum apogee detection algorithm fires exactly at
1127 apogee. If you are also flying an altimeter like the
1128 PerfectFlite MAWD, which only supports selecting 0 or 1
1129 seconds of apogee delay, you may wish to set the MAWD to 0
1130 seconds delay and set the TeleMetrum to fire your backup 2
1131 or 3 seconds later to avoid any chance of both charges
1132 firing simultaneously. We've flown several air-frames this
1133 way quite happily, including Keith's successful L3 cert.
1137 <title>Main Deployment Altitude</title>
1139 By default, the altimeter will fire the main deployment charge at an
1140 elevation of 250 meters (about 820 feet) above ground. We think this
1141 is a good elevation for most air-frames, but feel free to change this
1142 to suit. In particular, if you are flying two altimeters, you may
1144 deployment elevation for the backup altimeter to be something lower
1145 than the primary so that both pyrotechnic charges don't fire
1150 <title>Maximum Flight Log</title>
1152 Changing this value will set the maximum amount of flight
1153 log storage that an individual flight will use. The
1154 available storage is divided into as many flights of the
1155 specified size as can fit in the available space. You can
1156 download and erase individual flight logs. If you fill up
1157 the available storage, future flights will not get logged
1158 until you erase some of the stored ones.
1161 Even though our flight computers (except TeleMini v1.0) can store
1162 multiple flights, we strongly recommend downloading and saving
1163 flight data after each flight.
1167 <title>Ignite Mode</title>
1169 Instead of firing one charge at apogee and another charge at
1170 a fixed height above the ground, you can configure the
1171 altimeter to fire both at apogee or both during
1172 descent. This was added to support an airframe Bdale designed that
1173 had two altimeters, one in the fin can and one in the nose.
1176 Providing the ability to use both igniters for apogee or
1177 main allows some level of redundancy without needing two
1178 flight computers. In Redundant Apogee or Redundant Main
1179 mode, the two charges will be fired two seconds apart.
1183 <title>Pad Orientation</title>
1185 TeleMetrum and TeleMega measure acceleration along the axis
1186 of the board. Which way the board is oriented affects the
1187 sign of the acceleration value. Instead of trying to guess
1188 which way the board is mounted in the air frame, the
1189 altimeter must be explicitly configured for either Antenna
1190 Up or Antenna Down. The default, Antenna Up, expects the end
1191 of the board connected to the 70cm antenna to be nearest the
1192 nose of the rocket, with the end containing the screw
1193 terminals nearest the tail.
1197 <title>Configurable Pyro Channels</title>
1199 In addition to the usual Apogee and Main pyro channels,
1200 TeleMega has four additional channels that can be configured
1201 to activate when various flight conditions are
1202 satisfied. You can select as many conditions as necessary;
1203 all of them must be met in order to activate the
1204 channel. The conditions available are:
1209 Acceleration away from the ground. Select a value, and
1210 then choose whether acceleration should be above or
1211 below that value. Acceleration is positive upwards, so
1212 accelerating towards the ground would produce negative
1213 numbers. Acceleration during descent is noisy and
1214 inaccurate, so be careful when using it during these
1215 phases of the flight.
1220 Vertical speed. Select a value, and then choose whether
1221 vertical speed should be above or below that
1222 value. Speed is positive upwards, so moving towards the
1223 ground would produce negative numbers. Speed during
1224 descent is a bit noisy and so be careful when using it
1225 during these phases of the flight.
1230 Height. Select a value, and then choose whether the
1231 height above the launch pad should be above or below
1237 Orientation. TeleMega contains a 3-axis gyroscope and
1238 accelerometer which is used to measure the current
1239 angle. Note that this angle is not the change in angle
1240 from the launch pad, but rather absolute relative to
1241 gravity; the 3-axis accelerometer is used to compute the
1242 angle of the rocket on the launch pad and initialize the
1243 system. Because this value is computed by integrating
1244 rate gyros, it gets progressively less accurate as the
1245 flight goes on. It should have an accumulated error of
1246 less than 0.2°/second (after 10 seconds of flight, the
1247 error should be less than 2°).
1250 The usual use of the orientation configuration is to
1251 ensure that the rocket is traveling mostly upwards when
1252 deciding whether to ignite air starts or additional
1253 stages. For that, choose a reasonable maximum angle
1254 (like 20°) and set the motor igniter to require an angle
1255 of less than that value.
1260 Flight Time. Time since boost was detected. Select a
1261 value and choose whether to activate the pyro channel
1262 before or after that amount of time.
1267 Ascending. A simple test saying whether the rocket is
1268 going up or not. This is exactly equivalent to testing
1269 whether the speed is > 0.
1274 Descending. A simple test saying whether the rocket is
1275 going down or not. This is exactly equivalent to testing
1276 whether the speed is < 0.
1281 After Motor. The flight software counts each time the
1282 rocket starts accelerating (presumably due to a motor or
1283 motors igniting). Use this value to count ignitions for
1284 multi-staged or multi-airstart launches.
1289 Delay. This value doesn't perform any checks, instead it
1290 inserts a delay between the time when the other
1291 parameters become true and when the pyro channel is
1297 Flight State. The flight software tracks the flight
1298 through a sequence of states:
1302 Boost. The motor has lit and the rocket is
1303 accelerating upwards.
1308 Fast. The motor has burned out and the rocket is
1309 descellerating, but it is going faster than 200m/s.
1314 Coast. The rocket is still moving upwards and
1315 decelerating, but the speed is less than 200m/s.
1320 Drogue. The rocket has reached apogee and is heading
1321 back down, but is above the configured Main
1327 Main. The rocket is still descending, and is below
1333 Landed. The rocket is no longer moving.
1339 You can select a state to limit when the pyro channel
1340 may activate; note that the check is based on when the
1341 rocket transitions <emphasis>into</emphasis> the state, and so checking for
1342 “greater than Boost” means that the rocket is currently
1343 in boost or some later state.
1346 When a motor burns out, the rocket enters either Fast or
1347 Coast state (depending on how fast it is moving). If the
1348 computer detects upwards acceleration again, it will
1349 move back to Boost state.
1358 <title>AltosUI</title>
1360 The AltosUI program provides a graphical user interface for
1361 interacting with the Altus Metrum product family. AltosUI can
1362 monitor telemetry data, configure devices and many other
1363 tasks. The primary interface window provides a selection of
1364 buttons, one for each major activity in the system. This chapter
1365 is split into sections, each of which documents one of the tasks
1366 provided from the top-level toolbar.
1370 <imagedata fileref="altosui.png" width="5.5in"/>
1374 <title>Monitor Flight</title>
1375 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
1377 Selecting this item brings up a dialog box listing all of the
1378 connected TeleDongle devices. When you choose one of these,
1379 AltosUI will create a window to display telemetry data as
1380 received by the selected TeleDongle device.
1383 All telemetry data received are automatically recorded in
1384 suitable log files. The name of the files includes the current
1385 date and rocket serial and flight numbers.
1388 The radio frequency being monitored by the TeleDongle device is
1389 displayed at the top of the window. You can configure the
1390 frequency by clicking on the frequency box and selecting the desired
1391 frequency. AltosUI remembers the last frequency selected for each
1392 TeleDongle and selects that automatically the next time you use
1396 Below the TeleDongle frequency selector, the window contains a few
1397 significant pieces of information about the altimeter providing
1398 the telemetry data stream:
1402 <para>The configured call-sign</para>
1405 <para>The device serial number</para>
1408 <para>The flight number. Each altimeter remembers how many
1414 The rocket flight state. Each flight passes through several
1415 states including Pad, Boost, Fast, Coast, Drogue, Main and
1421 The Received Signal Strength Indicator value. This lets
1422 you know how strong a signal TeleDongle is receiving. The
1423 radio inside TeleDongle operates down to about -99dBm;
1424 weaker signals may not be receivable. The packet link uses
1425 error detection and correction techniques which prevent
1426 incorrect data from being reported.
1431 The age of the displayed data, in seconds since the last
1432 successfully received telemetry packet. In normal operation
1433 this will stay in the low single digits. If the number starts
1434 counting up, then you are no longer receiving data over the radio
1435 link from the flight computer.
1440 Finally, the largest portion of the window contains a set of
1441 tabs, each of which contain some information about the rocket.
1442 They're arranged in 'flight order' so that as the flight
1443 progresses, the selected tab automatically switches to display
1444 data relevant to the current state of the flight. You can select
1445 other tabs at any time. The final 'table' tab displays all of
1446 the raw telemetry values in one place in a spreadsheet-like format.
1449 <title>Launch Pad</title>
1451 The 'Launch Pad' tab shows information used to decide when the
1452 rocket is ready for flight. The first elements include red/green
1453 indicators, if any of these is red, you'll want to evaluate
1454 whether the rocket is ready to launch:
1457 <term>Battery Voltage</term>
1460 This indicates whether the Li-Po battery powering the
1461 flight computer has sufficient charge to last for
1462 the duration of the flight. A value of more than
1463 3.8V is required for a 'GO' status.
1468 <term>Apogee Igniter Voltage</term>
1471 This indicates whether the apogee
1472 igniter has continuity. If the igniter has a low
1473 resistance, then the voltage measured here will be close
1474 to the Li-Po battery voltage. A value greater than 3.2V is
1475 required for a 'GO' status.
1480 <term>Main Igniter Voltage</term>
1483 This indicates whether the main
1484 igniter has continuity. If the igniter has a low
1485 resistance, then the voltage measured here will be close
1486 to the Li-Po battery voltage. A value greater than 3.2V is
1487 required for a 'GO' status.
1492 <term>On-board Data Logging</term>
1495 This indicates whether there is
1496 space remaining on-board to store flight data for the
1497 upcoming flight. If you've downloaded data, but failed
1498 to erase flights, there may not be any space
1499 left. Most of our flight computers can store multiple
1500 flights, depending on the configured maximum flight log
1501 size. TeleMini v1.0 stores only a single flight, so it
1503 downloaded and erased after each flight to capture
1504 data. This only affects on-board flight logging; the
1505 altimeter will still transmit telemetry and fire
1506 ejection charges at the proper times even if the flight
1507 data storage is full.
1512 <term>GPS Locked</term>
1515 For a TeleMetrum or TeleMega device, this indicates whether the GPS receiver is
1516 currently able to compute position information. GPS requires
1517 at least 4 satellites to compute an accurate position.
1522 <term>GPS Ready</term>
1525 For a TeleMetrum or TeleMega device, this indicates whether GPS has reported at least
1526 10 consecutive positions without losing lock. This ensures
1527 that the GPS receiver has reliable reception from the
1535 The Launchpad tab also shows the computed launch pad position
1536 and altitude, averaging many reported positions to improve the
1537 accuracy of the fix.
1541 <title>Ascent</title>
1543 This tab is shown during Boost, Fast and Coast
1544 phases. The information displayed here helps monitor the
1545 rocket as it heads towards apogee.
1548 The height, speed and acceleration are shown along with the
1549 maximum values for each of them. This allows you to quickly
1550 answer the most commonly asked questions you'll hear during
1554 The current latitude and longitude reported by the GPS are
1555 also shown. Note that under high acceleration, these values
1556 may not get updated as the GPS receiver loses position
1557 fix. Once the rocket starts coasting, the receiver should
1558 start reporting position again.
1561 Finally, the current igniter voltages are reported as in the
1562 Launch Pad tab. This can help diagnose deployment failures
1563 caused by wiring which comes loose under high acceleration.
1567 <title>Descent</title>
1569 Once the rocket has reached apogee and (we hope) activated the
1570 apogee charge, attention switches to tracking the rocket on
1571 the way back to the ground, and for dual-deploy flights,
1572 waiting for the main charge to fire.
1575 To monitor whether the apogee charge operated correctly, the
1576 current descent rate is reported along with the current
1577 height. Good descent rates vary based on the choice of recovery
1578 components, but generally range from 15-30m/s on drogue and should
1579 be below 10m/s when under the main parachute in a dual-deploy flight.
1582 With GPS-equipped flight computers, you can locate the rocket in the
1583 sky using the elevation and bearing information to figure
1584 out where to look. Elevation is in degrees above the
1585 horizon. Bearing is reported in degrees relative to true
1586 north. Range can help figure out how big the rocket will
1587 appear. Ground Distance shows how far it is to a point
1588 directly under the rocket and can help figure out where the
1589 rocket is likely to land. Note that all of these values are
1590 relative to the pad location. If the elevation is near 90°,
1591 the rocket is over the pad, not over you.
1594 Finally, the igniter voltages are reported in this tab as
1595 well, both to monitor the main charge as well as to see what
1596 the status of the apogee charge is. Note that some commercial
1597 e-matches are designed to retain continuity even after being
1598 fired, and will continue to show as green or return from red to
1603 <title>Landed</title>
1605 Once the rocket is on the ground, attention switches to
1606 recovery. While the radio signal is often lost once the
1607 rocket is on the ground, the last reported GPS position is
1608 generally within a short distance of the actual landing location.
1611 The last reported GPS position is reported both by
1612 latitude and longitude as well as a bearing and distance from
1613 the launch pad. The distance should give you a good idea of
1614 whether to walk or hitch a ride. Take the reported
1615 latitude and longitude and enter them into your hand-held GPS
1616 unit and have that compute a track to the landing location.
1619 Our flight computers will continue to transmit RDF
1620 tones after landing, allowing you to locate the rocket by
1621 following the radio signal if necessary. You may need to get
1622 away from the clutter of the flight line, or even get up on
1623 a hill (or your neighbor's RV roof) to receive the RDF signal.
1626 The maximum height, speed and acceleration reported
1627 during the flight are displayed for your admiring observers.
1628 The accuracy of these immediate values depends on the quality
1629 of your radio link and how many packets were received.
1630 Recovering the on-board data after flight may yield
1631 more precise results.
1634 To get more detailed information about the flight, you can
1635 click on the 'Graph Flight' button which will bring up a
1636 graph window for the current flight.
1640 <title>Site Map</title>
1642 When the TeleMetrum has a GPS fix, the Site Map tab will map
1643 the rocket's position to make it easier for you to locate the
1644 rocket, both while it is in the air, and when it has landed. The
1645 rocket's state is indicated by color: white for pad, red for
1646 boost, pink for fast, yellow for coast, light blue for drogue,
1647 dark blue for main, and black for landed.
1650 The map's scale is approximately 3m (10ft) per pixel. The map
1651 can be dragged using the left mouse button. The map will attempt
1652 to keep the rocket roughly centered while data is being received.
1655 Images are fetched automatically via the Google Maps Static API,
1656 and cached on disk for reuse. If map images cannot be downloaded,
1657 the rocket's path will be traced on a dark gray background
1661 You can pre-load images for your favorite launch sites
1662 before you leave home; check out the 'Preload Maps' section below.
1667 <title>Save Flight Data</title>
1669 The altimeter records flight data to its internal flash memory.
1670 TeleMetrum data is recorded at a much higher rate than the telemetry
1671 system can handle, and is not subject to radio drop-outs. As
1672 such, it provides a more complete and precise record of the
1673 flight. The 'Save Flight Data' button allows you to read the
1674 flash memory and write it to disk.
1677 Clicking on the 'Save Flight Data' button brings up a list of
1678 connected flight computers and TeleDongle devices. If you select a
1679 flight computer, the flight data will be downloaded from that
1680 device directly. If you select a TeleDongle device, flight data
1681 will be downloaded from a flight computer over radio link via the
1682 specified TeleDongle. See the chapter on Controlling An Altimeter
1683 Over The Radio Link for more information.
1686 After the device has been selected, a dialog showing the
1687 flight data saved in the device will be shown allowing you to
1688 select which flights to download and which to delete. With
1689 version 0.9 or newer firmware, you must erase flights in order
1690 for the space they consume to be reused by another
1691 flight. This prevents accidentally losing flight data
1692 if you neglect to download data before flying again. Note that
1693 if there is no more space available in the device, then no
1694 data will be recorded during the next flight.
1697 The file name for each flight log is computed automatically
1698 from the recorded flight date, altimeter serial number and
1699 flight number information.
1703 <title>Replay Flight</title>
1705 Select this button and you are prompted to select a flight
1706 record file, either a .telem file recording telemetry data or a
1707 .eeprom file containing flight data saved from the altimeter
1711 Once a flight record is selected, the flight monitor interface
1712 is displayed and the flight is re-enacted in real time. Check
1713 the Monitor Flight chapter above to learn how this window operates.
1717 <title>Graph Data</title>
1719 Select this button and you are prompted to select a flight
1720 record file, either a .telem file recording telemetry data or a
1721 .eeprom file containing flight data saved from
1725 Once a flight record is selected, a window with multiple tabs is
1729 <term>Flight Graph</term>
1732 By default, the graph contains acceleration (blue),
1733 velocity (green) and altitude (red).
1738 <term>Configure Graph</term>
1741 This selects which graph elements to show, and, at the
1742 very bottom, lets you switch between metric and
1748 <term>Flight Statistics</term>
1751 Shows overall data computed from the flight.
1759 Shows a satellite image of the flight area overlaid
1760 with the path of the flight. The red concentric
1761 circles mark the launch pad, the black concentric
1762 circles mark the landing location.
1769 The graph can be zoomed into a particular area by clicking and
1770 dragging down and to the right. Once zoomed, the graph can be
1771 reset by clicking and dragging up and to the left. Holding down
1772 control and clicking and dragging allows the graph to be panned.
1773 The right mouse button causes a pop-up menu to be displayed, giving
1774 you the option save or print the plot.
1777 Note that telemetry files will generally produce poor graphs
1778 due to the lower sampling rate and missed telemetry packets.
1779 Use saved flight data in .eeprom files for graphing where possible.
1783 <title>Export Data</title>
1785 This tool takes the raw data files and makes them available for
1786 external analysis. When you select this button, you are prompted to
1787 select a flight data file, which can be either a .eeprom or .telem.
1788 The .eeprom files contain higher resolution and more continuous data,
1789 while .telem files contain receiver signal strength information.
1790 Next, a second dialog appears which is used to select
1791 where to write the resulting file. It has a selector to choose
1792 between CSV and KML file formats.
1795 <title>Comma Separated Value Format</title>
1797 This is a text file containing the data in a form suitable for
1798 import into a spreadsheet or other external data analysis
1799 tool. The first few lines of the file contain the version and
1800 configuration information from the altimeter, then
1801 there is a single header line which labels all of the
1802 fields. All of these lines start with a '#' character which
1803 many tools can be configured to skip over.
1806 The remaining lines of the file contain the data, with each
1807 field separated by a comma and at least one space. All of
1808 the sensor values are converted to standard units, with the
1809 barometric data reported in both pressure, altitude and
1810 height above pad units.
1814 <title>Keyhole Markup Language (for Google Earth)</title>
1816 This is the format used by Google Earth to provide an overlay
1817 within that application. With this, you can use Google Earth to
1818 see the whole flight path in 3D.
1823 <title>Configure Altimeter</title>
1825 Select this button and then select either an altimeter or
1826 TeleDongle Device from the list provided. Selecting a TeleDongle
1827 device will use the radio link to configure a remote altimeter.
1830 The first few lines of the dialog provide information about the
1831 connected device, including the product name,
1832 software version and hardware serial number. Below that are the
1833 individual configuration entries.
1836 At the bottom of the dialog, there are four buttons:
1843 This writes any changes to the
1844 configuration parameter block in flash memory. If you don't
1845 press this button, any changes you make will be lost.
1853 This resets the dialog to the most recently saved values,
1854 erasing any changes you have made.
1862 This reboots the device. Use this to
1863 switch from idle to pad mode by rebooting once the rocket is
1864 oriented for flight, or to confirm changes you think you saved
1873 This closes the dialog. Any unsaved changes will be
1880 The rest of the dialog contains the parameters to be configured.
1883 <title>Main Deploy Altitude</title>
1885 This sets the altitude (above the recorded pad altitude) at
1886 which the 'main' igniter will fire. The drop-down menu shows
1887 some common values, but you can edit the text directly and
1888 choose whatever you like. If the apogee charge fires below
1889 this altitude, then the main charge will fire two seconds
1890 after the apogee charge fires.
1894 <title>Apogee Delay</title>
1896 When flying redundant electronics, it's often important to
1897 ensure that multiple apogee charges don't fire at precisely
1898 the same time, as that can over pressurize the apogee deployment
1899 bay and cause a structural failure of the air-frame. The Apogee
1900 Delay parameter tells the flight computer to fire the apogee
1901 charge a certain number of seconds after apogee has been
1906 <title>Radio Frequency</title>
1908 This configures which of the frequencies to use for both
1909 telemetry and packet command mode. Note that if you set this
1910 value via packet command mode, the TeleDongle frequency will
1911 also be automatically reconfigured to match so that
1912 communication will continue afterwards.
1916 <title>RF Calibration</title>
1918 The radios in every Altus Metrum device are calibrated at the
1919 factory to ensure that they transmit and receive on the
1920 specified frequency. If you need to you can adjust the calibration
1921 by changing this value. Do not do this without understanding what
1922 the value means, read the appendix on calibration and/or the source
1923 code for more information. To change a TeleDongle's calibration,
1924 you must reprogram the unit completely.
1928 <title>Telemetry/RDF/APRS Enable</title>
1930 Enables the radio for transmission during flight. When
1931 disabled, the radio will not transmit anything during flight
1936 <title>APRS Interval</title>
1938 How often to transmit GPS information via APRS. This option
1939 is available on TeleMetrum v2 and TeleMega
1940 boards. TeleMetrum v1 boards cannot transmit APRS
1941 packets. Note that a single APRS packet takes nearly a full
1942 second to transmit, so enabling this option will prevent
1943 sending any other telemetry during that time.
1947 <title>Callsign</title>
1949 This sets the call sign included in each telemetry packet. Set this
1950 as needed to conform to your local radio regulations.
1954 <title>Maximum Flight Log Size</title>
1956 This sets the space (in kilobytes) allocated for each flight
1957 log. The available space will be divided into chunks of this
1958 size. A smaller value will allow more flights to be stored,
1959 a larger value will record data from longer flights.
1963 <title>Ignite Mode</title>
1965 TeleMetrum and TeleMini provide two igniter channels as they
1966 were originally designed as dual-deploy flight
1967 computers. This configuration parameter allows the two
1968 channels to be used in different configurations.
1972 <term>Dual Deploy</term>
1975 This is the usual mode of operation; the
1976 'apogee' channel is fired at apogee and the 'main'
1977 channel at the height above ground specified by the
1978 'Main Deploy Altitude' during descent.
1983 <term>Redundant Apogee</term>
1986 This fires both channels at
1987 apogee, the 'apogee' channel first followed after a two second
1988 delay by the 'main' channel.
1993 <term>Redundant Main</term>
1996 This fires both channels at the
1997 height above ground specified by the Main Deploy
1998 Altitude setting during descent. The 'apogee'
1999 channel is fired first, followed after a two second
2000 delay by the 'main' channel.
2007 <title>Pad Orientation</title>
2009 Because they include accelerometers, TeleMetrum and
2010 TeleMega are sensitive to the orientation of the board. By
2011 default, they expect the antenna end to point forward. This
2012 parameter allows that default to be changed, permitting the
2013 board to be mounted with the antenna pointing aft instead.
2017 <term>Antenna Up</term>
2020 In this mode, the antenna end of the
2021 flight computer must point forward, in line with the
2022 expected flight path.
2027 <term>Antenna Down</term>
2030 In this mode, the antenna end of the
2031 flight computer must point aft, in line with the
2032 expected flight path.
2039 <title>Configure Pyro Channels</title>
2041 This opens a separate window to configure the additional
2042 pyro channels available on TeleMega. One column is
2043 presented for each channel. Each row represents a single
2044 parameter, if enabled the parameter must meet the specified
2045 test for the pyro channel to be fired. See the Pyro Channels
2046 section in the System Operation chapter above for a
2047 description of these parameters.
2050 Select conditions and set the related value; the pyro
2051 channel will be activated when <emphasis>all</emphasis> of the
2052 conditions are met. Each pyro channel has a separate set of
2053 configuration values, so you can use different values for
2054 the same condition with different channels.
2057 Once you have selected the appropriate configuration for all
2058 of the necessary pyro channels, you can save the pyro
2059 configuration along with the rest of the flight computer
2060 configuration by pressing the 'Save' button in the main
2061 Configure Flight Computer window.
2066 <title>Configure AltosUI</title>
2068 This button presents a dialog so that you can configure the AltosUI global settings.
2071 <title>Voice Settings</title>
2073 AltosUI provides voice announcements during flight so that you
2074 can keep your eyes on the sky and still get information about
2075 the current flight status. However, sometimes you don't want
2080 <para>Enable—turns all voice announcements on and off</para>
2084 Test Voice—Plays a short message allowing you to verify
2085 that the audio system is working and the volume settings
2092 <title>Log Directory</title>
2094 AltosUI logs all telemetry data and saves all TeleMetrum flash
2095 data to this directory. This directory is also used as the
2096 staring point when selecting data files for display or export.
2099 Click on the directory name to bring up a directory choosing
2100 dialog, select a new directory and click 'Select Directory' to
2101 change where AltosUI reads and writes data files.
2105 <title>Callsign</title>
2107 This value is transmitted in each command packet sent from
2108 TeleDongle and received from an altimeter. It is not used in
2109 telemetry mode, as the callsign configured in the altimeter board
2110 is included in all telemetry packets. Configure this
2111 with the AltosUI operators call sign as needed to comply with
2112 your local radio regulations.
2115 Note that to successfully command a flight computer over the radio
2116 (to configure the altimeter, monitor idle, or fire pyro charges),
2117 the callsign configured here must exactly match the callsign
2118 configured in the flight computer. This matching is case
2123 <title>Imperial Units</title>
2125 This switches between metric units (meters) and imperial
2126 units (feet and miles). This affects the display of values
2127 use during flight monitoring, configuration, data graphing
2128 and all of the voice announcements. It does not change the
2129 units used when exporting to CSV files, those are always
2130 produced in metric units.
2134 <title>Font Size</title>
2136 Selects the set of fonts used in the flight monitor
2137 window. Choose between the small, medium and large sets.
2141 <title>Serial Debug</title>
2143 This causes all communication with a connected device to be
2144 dumped to the console from which AltosUI was started. If
2145 you've started it from an icon or menu entry, the output
2146 will simply be discarded. This mode can be useful to debug
2147 various serial communication issues.
2151 <title>Manage Frequencies</title>
2153 This brings up a dialog where you can configure the set of
2154 frequencies shown in the various frequency menus. You can
2155 add as many as you like, or even reconfigure the default
2156 set. Changing this list does not affect the frequency
2157 settings of any devices, it only changes the set of
2158 frequencies shown in the menus.
2163 <title>Configure Groundstation</title>
2165 Select this button and then select a TeleDongle Device from the list provided.
2168 The first few lines of the dialog provide information about the
2169 connected device, including the product name,
2170 software version and hardware serial number. Below that are the
2171 individual configuration entries.
2174 Note that the TeleDongle itself doesn't save any configuration
2175 data, the settings here are recorded on the local machine in
2176 the Java preferences database. Moving the TeleDongle to
2177 another machine, or using a different user account on the same
2178 machine will cause settings made here to have no effect.
2181 At the bottom of the dialog, there are three buttons:
2188 This writes any changes to the
2189 local Java preferences file. If you don't
2190 press this button, any changes you make will be lost.
2198 This resets the dialog to the most recently saved values,
2199 erasing any changes you have made.
2207 This closes the dialog. Any unsaved changes will be
2214 The rest of the dialog contains the parameters to be configured.
2217 <title>Frequency</title>
2219 This configures the frequency to use for both telemetry and
2220 packet command mode. Set this before starting any operation
2221 involving packet command mode so that it will use the right
2222 frequency. Telemetry monitoring mode also provides a menu to
2223 change the frequency, and that menu also sets the same Java
2224 preference value used here.
2228 <title>Radio Calibration</title>
2230 The radios in every Altus Metrum device are calibrated at the
2231 factory to ensure that they transmit and receive on the
2232 specified frequency. To change a TeleDongle's calibration,
2233 you must reprogram the unit completely, so this entry simply
2234 shows the current value and doesn't allow any changes.
2239 <title>Flash Image</title>
2241 This reprograms Altus Metrum devices with new
2242 firmware. TeleMetrum v1.x, TeleDongle, TeleMini and TeleBT are
2243 all reprogrammed by using another similar unit as a
2244 programming dongle (pair programming). TeleMega, TeleMetrum v2
2245 and EasyMini are all programmed directly over their USB ports
2246 (self programming). Please read the directions for flashing
2247 devices in the Updating Device Firmware chapter below.
2250 For “self programming”, connect USB to the device to be
2251 programmed and push the 'Flash Image' button. That will
2252 present a dialog box listing all of the connected
2253 devices. Carefully select the device to be programmed.
2256 For “pair programming”, once you have the programmer and
2257 target devices connected, push the 'Flash Image' button. That
2258 will present a dialog box listing all of the connected
2259 devices. Carefully select the programmer device, not the
2260 device to be programmed.
2263 Next, select the image to flash to the device. These are named
2264 with the product name and firmware version. The file selector
2265 will start in the directory containing the firmware included
2266 with the AltosUI package. Navigate to the directory containing
2267 the desired firmware if it isn't there.
2270 Next, a small dialog containing the device serial number and
2271 RF calibration values should appear. If these values are
2272 incorrect (possibly due to a corrupted image in the device),
2273 enter the correct values here.
2276 Finally, a dialog containing a progress bar will follow the
2277 programming process.
2280 When programming is complete, the target device will
2281 reboot. Note that if a pair programmed target device is
2282 connected via USB, you will have to unplug it and then plug it
2283 back in for the USB connection to reset so that you can
2284 communicate with the device again.
2288 <title>Fire Igniter</title>
2290 This activates the igniter circuits in the flight computer to help
2291 test recovery systems deployment. Because this command can operate
2292 over the Packet Command Link, you can prepare the rocket as
2293 for flight and then test the recovery system without needing
2294 to snake wires inside the air-frame.
2297 Selecting the 'Fire Igniter' button brings up the usual device
2298 selection dialog. Pick the desired device. This brings up another
2299 window which shows the current continuity test status for both
2300 apogee and main charges.
2303 Next, select the desired igniter to fire. This will enable the
2307 Select the 'Arm' button. This enables the 'Fire' button. The
2308 word 'Arm' is replaced by a countdown timer indicating that
2309 you have 10 seconds to press the 'Fire' button or the system
2310 will deactivate, at which point you start over again at
2311 selecting the desired igniter.
2315 <title>Scan Channels</title>
2317 This listens for telemetry packets on all of the configured
2318 frequencies, displaying information about each device it
2319 receives a packet from. You can select which of the three
2320 telemetry formats should be tried; by default, it only listens
2321 for the standard telemetry packets used in v1.0 and later
2326 <title>Load Maps</title>
2328 Before heading out to a new launch site, you can use this to
2329 load satellite images in case you don't have internet
2330 connectivity at the site. This loads a fairly large area
2331 around the launch site, which should cover any flight you're likely to make.
2334 There's a drop-down menu of launch sites we know about; if
2335 your favorites aren't there, please let us know the lat/lon
2336 and name of the site. The contents of this list are actually
2337 downloaded from our server at run-time, so as new sites are sent
2338 in, they'll get automatically added to this list.
2341 If the launch site isn't in the list, you can manually enter the lat/lon values
2344 Clicking the 'Load Map' button will fetch images from Google
2345 Maps; note that Google limits how many images you can fetch at
2346 once, so if you load more than one launch site, you may get
2347 some gray areas in the map which indicate that Google is tired
2348 of sending data to you. Try again later.
2352 <title>Monitor Idle</title>
2354 This brings up a dialog similar to the Monitor Flight UI,
2355 except it works with the altimeter in “idle” mode by sending
2356 query commands to discover the current state rather than
2357 listening for telemetry packets. Because this uses command
2358 mode, it needs to have the TeleDongle and flight computer
2359 callsigns match exactly. If you can receive telemetry, but
2360 cannot manage to run Monitor Idle, then it's very likely that
2361 your callsigns are different in some way.
2366 <title>AltosDroid</title>
2368 AltosDroid provides the same flight monitoring capabilities as
2369 AltosUI, but runs on Android devices and is designed to connect
2370 to a TeleBT receiver over Bluetooth™. AltosDroid monitors
2371 telemetry data, logging it to internal storage in the Android
2372 device, and presents that data in a UI the same way the 'Monitor
2373 Flight' window does in AltosUI.
2376 This manual will explain how to configure AltosDroid, connect
2377 to TeleBT, operate the flight monitoring interface and describe
2378 what the displayed data means.
2381 <title>Installing AltosDroid</title>
2383 AltosDroid is available from the Google Play store. To install
2384 it on your Android device, open the Google Play Store
2385 application and search for “altosdroid”. Make sure you don't
2386 have a space between “altos” and “droid” or you probably won't
2387 find what you want. That should bring you to the right page
2388 from which you can download and install the application.
2392 <title>Connecting to TeleBT</title>
2394 Press the Android 'Menu' button or soft-key to see the
2395 configuration options available. Select the 'Connect a device'
2396 option and then the 'Scan for devices' entry at the bottom to
2397 look for your TeleBT device. Select your device, and when it
2398 asks for the code, enter '1234'.
2401 Subsequent connections will not require you to enter that
2402 code, and your 'paired' device will appear in the list without
2407 <title>Configuring AltosDroid</title>
2409 The only configuration option available for AltosDroid is
2410 which frequency to listen on. Press the Android 'Menu' button
2411 or soft-key and pick the 'Select radio frequency' entry. That
2412 brings up a menu of pre-set radio frequencies; pick the one
2413 which matches your altimeter.
2417 <title>AltosDroid Flight Monitoring</title>
2419 AltosDroid is designed to mimic the AltosUI flight monitoring
2420 display, providing separate tabs for each stage of your rocket
2421 flight along with a tab containing a map of the local area
2422 with icons marking the current location of the altimeter and
2428 The 'Launch Pad' tab shows information used to decide when the
2429 rocket is ready for flight. The first elements include red/green
2430 indicators, if any of these is red, you'll want to evaluate
2431 whether the rocket is ready to launch:
2434 <term>Battery Voltage</term>
2437 This indicates whether the Li-Po battery
2438 powering the TeleMetrum has sufficient charge to last for
2439 the duration of the flight. A value of more than
2440 3.8V is required for a 'GO' status.
2445 <term>Apogee Igniter Voltage</term>
2448 This indicates whether the apogee
2449 igniter has continuity. If the igniter has a low
2450 resistance, then the voltage measured here will be close
2451 to the Li-Po battery voltage. A value greater than 3.2V is
2452 required for a 'GO' status.
2457 <term>Main Igniter Voltage</term>
2460 This indicates whether the main
2461 igniter has continuity. If the igniter has a low
2462 resistance, then the voltage measured here will be close
2463 to the Li-Po battery voltage. A value greater than 3.2V is
2464 required for a 'GO' status.
2469 <term>On-board Data Logging</term>
2472 This indicates whether there is
2473 space remaining on-board to store flight data for the
2474 upcoming flight. If you've downloaded data, but failed
2475 to erase flights, there may not be any space
2476 left. TeleMetrum can store multiple flights, depending
2477 on the configured maximum flight log size. TeleMini
2478 stores only a single flight, so it will need to be
2479 downloaded and erased after each flight to capture
2480 data. This only affects on-board flight logging; the
2481 altimeter will still transmit telemetry and fire
2482 ejection charges at the proper times.
2487 <term>GPS Locked</term>
2490 For a TeleMetrum or TeleMega device, this indicates whether the GPS receiver is
2491 currently able to compute position information. GPS requires
2492 at least 4 satellites to compute an accurate position.
2497 <term>GPS Ready</term>
2500 For a TeleMetrum or TeleMega device, this indicates whether GPS has reported at least
2501 10 consecutive positions without losing lock. This ensures
2502 that the GPS receiver has reliable reception from the
2510 The Launchpad tab also shows the computed launch pad position
2511 and altitude, averaging many reported positions to improve the
2512 accuracy of the fix.
2517 <title>Downloading Flight Logs</title>
2519 AltosDroid always saves every bit of telemetry data it
2520 receives. To download that to a computer for use with AltosUI,
2521 simply remove the SD card from your Android device, or connect
2522 your device to your computer's USB port and browse the files
2523 on that device. You will find '.telem' files in the TeleMetrum
2524 directory that will work with AltosUI directly.
2529 <title>Using Altus Metrum Products</title>
2531 <title>Being Legal</title>
2533 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
2534 other authorization to legally operate the radio transmitters that are part
2539 <title>In the Rocket</title>
2541 In the rocket itself, you just need a flight computer and
2542 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
2543 850mAh battery weighs less than a 9V alkaline battery, and will
2544 run a TeleMetrum or TeleMega for hours.
2545 A 110mAh battery weighs less than a triple A battery and is a good
2546 choice for use with TeleMini.
2549 By default, we ship flight computers with a simple wire antenna.
2550 If your electronics bay or the air-frame it resides within is made
2551 of carbon fiber, which is opaque to RF signals, you may prefer to
2552 install an SMA connector so that you can run a coaxial cable to an
2553 antenna mounted elsewhere in the rocket. However, note that the
2554 GPS antenna is fixed on all current products, so you really want
2555 to install the flight computer in a bay made of RF-transparent
2556 materials if at all possible.
2560 <title>On the Ground</title>
2562 To receive the data stream from the rocket, you need an antenna and short
2563 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. If possible, use an SMA to BNC
2564 adapter instead of feedline between the antenna feedpoint and
2565 TeleDongle, as this will give you the best performance. The
2566 TeleDongle in turn plugs directly into the USB port on a notebook
2567 computer. Because TeleDongle looks like a simple serial port, your computer
2568 does not require special device drivers... just plug it in.
2571 The GUI tool, AltosUI, is written in Java and runs across
2572 Linux, Mac OS and Windows. There's also a suite of C tools
2573 for Linux which can perform most of the same tasks.
2576 Alternatively, a TeleBT attached with an SMA to BNC adapter at the
2577 feed point of a hand-held yagi used in conjunction with an Android
2578 device running AltosDroid makes an outstanding ground station.
2581 After the flight, you can use the radio link to extract the more detailed data
2582 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
2583 TeleMetrum board directly. Pulling out the data without having to open up
2584 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
2585 battery, so you'll want one of those anyway... the same cable used by lots
2586 of digital cameras and other modern electronic stuff will work fine.
2589 If your rocket lands out of sight, you may enjoy having a hand-held
2590 GPS receiver, so that you can put in a way-point for the last
2591 reported rocket position before touch-down. This makes looking for
2592 your rocket a lot like Geo-Caching... just go to the way-point and
2593 look around starting from there. AltosDroid on an Android device
2594 with GPS receiver works great for this, too!
2597 You may also enjoy having a ham radio “HT” that covers the 70cm band... you
2598 can use that with your antenna to direction-find the rocket on the ground
2599 the same way you can use a Walston or Beeline tracker. This can be handy
2600 if the rocket is hiding in sage brush or a tree, or if the last GPS position
2601 doesn't get you close enough because the rocket dropped into a canyon, or
2602 the wind is blowing it across a dry lake bed, or something like that... Keith
2603 currently uses a Yaesu VX-7R, Bdale has a Baofung UV-5R
2604 which isn't as nice, but was a whole lot cheaper.
2607 So, to recap, on the ground the hardware you'll need includes:
2608 <orderedlist inheritnum='inherit' numeration='arabic'>
2611 an antenna and feed-line or adapter
2626 optionally, a hand-held GPS receiver
2631 optionally, an HT or receiver covering 435 MHz
2637 The best hand-held commercial directional antennas we've found for radio
2638 direction finding rockets are from
2639 <ulink url="http://www.arrowantennas.com/" >
2642 The 440-3 and 440-5 are both good choices for finding a
2643 TeleMetrum- or TeleMini- equipped rocket when used with a suitable
2644 70cm HT. TeleDongle and an SMA to BNC adapter fit perfectly
2645 between the driven element and reflector of Arrow antennas.
2649 <title>Data Analysis</title>
2651 Our software makes it easy to log the data from each flight, both the
2652 telemetry received during the flight itself, and the more
2653 complete data log recorded in the flash memory on the altimeter
2654 board. Once this data is on your computer, our post-flight tools make it
2655 easy to quickly get to the numbers everyone wants, like apogee altitude,
2656 max acceleration, and max velocity. You can also generate and view a
2657 standard set of plots showing the altitude, acceleration, and
2658 velocity of the rocket during flight. And you can even export a TeleMetrum data file
2659 usable with Google Maps and Google Earth for visualizing the flight path
2660 in two or three dimensions!
2663 Our ultimate goal is to emit a set of files for each flight that can be
2664 published as a web page per flight, or just viewed on your local disk with
2669 <title>Future Plans</title>
2671 We've designed a simple GPS based radio tracker called TeleGPS.
2672 If all goes well, we hope to introduce this in the first
2676 We have designed and prototyped several “companion boards” that
2677 can attach to the companion connector on TeleMetrum and TeleMega
2678 flight computers to collect more data, provide more pyro channels,
2679 and so forth. We do not yet know if or when any of these boards
2680 will be produced in enough quantity to sell. If you have specific
2681 interests for data collection or control of events in your rockets
2682 beyond the capabilities of our existing productions, please let
2686 Because all of our work is open, both the hardware designs and the
2687 software, if you have some great idea for an addition to the current
2688 Altus Metrum family, feel free to dive in and help! Or let us know
2689 what you'd like to see that we aren't already working on, and maybe
2690 we'll get excited about it too...
2694 <ulink url="http://altusmetrum.org/">web site</ulink> for more news
2695 and information as our family of products evolves!
2700 <title>Altimeter Installation Recommendations</title>
2702 Building high-power rockets that fly safely is hard enough. Mix
2703 in some sophisticated electronics and a bunch of radio energy
2704 and some creativity and/or compromise may be required. This chapter
2705 contains some suggestions about how to install Altus Metrum
2706 products into a rocket air-frame, including how to safely and
2707 reliably mix a variety of electronics into the same air-frame.
2710 <title>Mounting the Altimeter</title>
2712 The first consideration is to ensure that the altimeter is
2713 securely fastened to the air-frame. For most of our products, we
2714 prefer nylon standoffs and nylon screws; they're good to at least 50G
2715 and cannot cause any electrical issues on the board. Metal screws
2716 and standoffs are fine, too, just be careful to avoid electrical
2717 shorts! For TeleMini v1.0, we usually cut small pieces of 1/16 inch
2719 under the screw holes, and then take 2x56 nylon screws and
2720 screw them through the TeleMini mounting holes, through the
2721 balsa and into the underlying material.
2723 <orderedlist inheritnum='inherit' numeration='arabic'>
2726 Make sure accelerometer-equipped products like TeleMetrum and
2727 TeleMega are aligned precisely along the axis of
2728 acceleration so that the accelerometer can accurately
2729 capture data during the flight.
2734 Watch for any metal touching components on the
2735 board. Shorting out connections on the bottom of the board
2736 can cause the altimeter to fail during flight.
2742 <title>Dealing with the Antenna</title>
2744 The antenna supplied is just a piece of solid, insulated,
2745 wire. If it gets damaged or broken, it can be easily
2746 replaced. It should be kept straight and not cut; bending or
2747 cutting it will change the resonant frequency and/or
2748 impedance, making it a less efficient radiator and thus
2749 reducing the range of the telemetry signal.
2752 Keeping metal away from the antenna will provide better range
2753 and a more even radiation pattern. In most rockets, it's not
2754 entirely possible to isolate the antenna from metal
2755 components; there are often bolts, all-thread and wires from other
2756 electronics to contend with. Just be aware that the more stuff
2757 like this around the antenna, the lower the range.
2760 Make sure the antenna is not inside a tube made or covered
2761 with conducting material. Carbon fiber is the most common
2762 culprit here -- CF is a good conductor and will effectively
2763 shield the antenna, dramatically reducing signal strength and
2764 range. Metallic flake paint is another effective shielding
2765 material which should be avoided around any antennas.
2768 If the ebay is large enough, it can be convenient to simply
2769 mount the altimeter at one end and stretch the antenna out
2770 inside. Taping the antenna to the sled can keep it straight
2771 under acceleration. If there are metal rods, keep the
2772 antenna as far away as possible.
2775 For a shorter ebay, it's quite practical to have the antenna
2776 run through a bulkhead and into an adjacent bay. Drill a small
2777 hole in the bulkhead, pass the antenna wire through it and
2778 then seal it up with glue or clay. We've also used acrylic
2779 tubing to create a cavity for the antenna wire. This works a
2780 bit better in that the antenna is known to stay straight and
2781 not get folded by recovery components in the bay. Angle the
2782 tubing towards the side wall of the rocket and it ends up
2783 consuming very little space.
2786 If you need to place the UHF antenna at a distance from the
2787 altimeter, you can replace the antenna with an edge-mounted
2788 SMA connector, and then run 50Ω coax from the board to the
2789 antenna. Building a remote antenna is beyond the scope of this
2794 <title>Preserving GPS Reception</title>
2796 The GPS antenna and receiver used in TeleMetrum and TeleMega is
2797 highly sensitive and normally have no trouble tracking enough
2798 satellites to provide accurate position information for
2799 recovering the rocket. However, there are many ways the GPS signal
2800 can end up attenuated, negatively affecting GPS performance.
2801 <orderedlist inheritnum='inherit' numeration='arabic'>
2804 Conductive tubing or coatings. Carbon fiber and metal
2805 tubing, or metallic paint will all dramatically attenuate the
2806 GPS signal. We've never heard of anyone successfully
2807 receiving GPS from inside these materials.
2812 Metal components near the GPS patch antenna. These will
2813 de-tune the patch antenna, changing the resonant frequency
2814 away from the L1 carrier and reduce the effectiveness of the
2815 antenna. You can place as much stuff as you like beneath the
2816 antenna as that's covered with a ground plane. But, keep
2817 wires and metal out from above the patch antenna.
2824 <title>Radio Frequency Interference</title>
2826 Any altimeter will generate RFI; the digital circuits use
2827 high-frequency clocks that spray radio interference across a
2828 wide band. Altus Metrum altimeters generate intentional radio
2829 signals as well, increasing the amount of RF energy around the board.
2832 Rocketry altimeters also use precise sensors measuring air
2833 pressure and acceleration. Tiny changes in voltage can cause
2834 these sensor readings to vary by a huge amount. When the
2835 sensors start mis-reporting data, the altimeter can either
2836 fire the igniters at the wrong time, or not fire them at all.
2839 Voltages are induced when radio frequency energy is
2840 transmitted from one circuit to another. Here are things that
2841 influence the induced voltage and current:
2846 Keep wires from different circuits apart. Moving circuits
2847 further apart will reduce RFI.
2852 Avoid parallel wires from different circuits. The longer two
2853 wires run parallel to one another, the larger the amount of
2854 transferred energy. Cross wires at right angles to reduce
2860 Twist wires from the same circuits. Two wires the same
2861 distance from the transmitter will get the same amount of
2862 induced energy which will then cancel out. Any time you have
2863 a wire pair running together, twist the pair together to
2864 even out distances and reduce RFI. For altimeters, this
2865 includes battery leads, switch hookups and igniter
2871 Avoid resonant lengths. Know what frequencies are present
2872 in the environment and avoid having wire lengths near a
2873 natural resonant length. Altus Metrum products transmit on the
2874 70cm amateur band, so you should avoid lengths that are a
2875 simple ratio of that length; essentially any multiple of ¼
2876 of the wavelength (17.5cm).
2882 <title>The Barometric Sensor</title>
2884 Altusmetrum altimeters measure altitude with a barometric
2885 sensor, essentially measuring the amount of air above the
2886 rocket to figure out how high it is. A large number of
2887 measurements are taken as the altimeter initializes itself to
2888 figure out the pad altitude. Subsequent measurements are then
2889 used to compute the height above the pad.
2892 To accurately measure atmospheric pressure, the ebay
2893 containing the altimeter must be vented outside the
2894 air-frame. The vent must be placed in a region of linear
2895 airflow, have smooth edges, and away from areas of increasing or
2896 decreasing pressure.
2899 All barometric sensors are quite sensitive to chemical damage from
2900 the products of APCP or BP combustion, so make sure the ebay is
2901 carefully sealed from any compartment which contains ejection
2906 <title>Ground Testing</title>
2908 The most important aspect of any installation is careful
2909 ground testing. Bringing an air-frame up to the LCO table which
2910 hasn't been ground tested can lead to delays or ejection
2911 charges firing on the pad, or, even worse, a recovery system
2915 Do a 'full systems' test that includes wiring up all igniters
2916 without any BP and turning on all of the electronics in flight
2917 mode. This will catch any mistakes in wiring and any residual
2918 RFI issues that might accidentally fire igniters at the wrong
2919 time. Let the air-frame sit for several minutes, checking for
2920 adequate telemetry signal strength and GPS lock. If any igniters
2921 fire unexpectedly, find and resolve the issue before loading any
2925 Ground test the ejection charges. Prepare the rocket for
2926 flight, loading ejection charges and igniters. Completely
2927 assemble the air-frame and then use the 'Fire Igniters'
2928 interface through a TeleDongle to command each charge to
2929 fire. Make sure the charge is sufficient to robustly separate
2930 the air-frame and deploy the recovery system.
2935 <title>Updating Device Firmware</title>
2937 TeleMega, TeleMetrum v2 and EasyMini are all programmed directly
2938 over their USB connectors (self programming). TeleMetrum v1, TeleMini and
2939 TeleDongle are all programmed by using another device as a
2940 programmer (pair programming). It's important to recognize which
2941 kind of devices you have before trying to reprogram them.
2944 You may wish to begin by ensuring you have current firmware images.
2945 These are distributed as part of the AltOS software bundle that
2946 also includes the AltosUI ground station program. Newer ground
2947 station versions typically work fine with older firmware versions,
2948 so you don't need to update your devices just to try out new
2949 software features. You can always download the most recent
2950 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
2953 If you need to update the firmware on a TeleDongle, we recommend
2954 updating the altimeter first, before updating TeleDongle. However,
2955 note that TeleDongle rarely need to be updated. Any firmware version
2956 1.0.1 or later will work, version 1.2.1 may have improved receiver
2957 performance slightly.
2960 Self-programmable devices (TeleMega, TeleMetrum v2 and EasyMini)
2961 are reprogrammed by connecting them to your computer over USB
2965 Updating TeleMega, TeleMetrum v2 or EasyMini Firmware
2967 <orderedlist inheritnum='inherit' numeration='arabic'>
2970 Attach a battery and power switch to the target
2971 device. Power up the device.
2976 Using a Micro USB cable, connect the target device to your
2977 computer's USB socket.
2982 Run AltosUI, and select 'Flash Image' from the File menu.
2987 Select the target device in the Device Selection dialog.
2992 Select the image you want to flash to the device, which
2993 should have a name in the form
2994 <product>-v<product-version>-<software-version>.ihx, such
2995 as TeleMega-v1.0-1.3.0.ihx.
3000 Make sure the configuration parameters are reasonable
3001 looking. If the serial number and/or RF configuration
3002 values aren't right, you'll need to change them.
3007 Hit the 'OK' button and the software should proceed to flash
3008 the device with new firmware, showing a progress bar.
3013 Verify that the device is working by using the 'Configure
3014 Altimeter' item to check over the configuration.
3019 <title>Recovering From Self-Flashing Failure</title>
3021 If the firmware loading fails, it can leave the device
3022 unable to boot. Not to worry, you can force the device to
3023 start the boot loader instead, which will let you try to
3024 flash the device again.
3027 On each device, connecting two pins from one of the exposed
3028 connectors will force the boot loader to start, even if the
3029 regular operating system has been corrupted in some way.
3033 <term>TeleMega</term>
3036 Connect pin 6 and pin 1 of the companion connector. Pin 1
3037 can be identified by the square pad around it, and then
3038 the pins could sequentially across the board. Be very
3039 careful to <emphasis>not</emphasis> short pin 8 to
3040 anything as that is connected directly to the battery. Pin
3041 7 carries 3.3V and the board will crash if that is
3042 connected to pin 1, but shouldn't damage the board.
3047 <term>TeleMetrum v2</term>
3050 Connect pin 6 and pin 1 of the companion connector. Pin 1
3051 can be identified by the square pad around it, and then
3052 the pins could sequentially across the board. Be very
3053 careful to <emphasis>not</emphasis> short pin 8 to
3054 anything as that is connected directly to the battery. Pin
3055 7 carries 3.3V and the board will crash if that is
3056 connected to pin 1, but shouldn't damage the board.
3061 <term>EasyMini</term>
3064 Connect pin 6 and pin 1 of the debug connector, which is
3065 the six holes next to the beeper. Pin 1 can be identified
3066 by the square pad around it, and then the pins could
3067 sequentially across the board, making Pin 6 the one on the
3068 other end of the row.
3076 <title>Pair Programming</title>
3078 The big concept to understand is that you have to use a
3079 TeleMega, TeleMetrum or TeleDongle as a programmer to update a
3080 pair programmed device. Due to limited memory resources in the
3081 cc1111, we don't support programming directly over USB for these
3086 <title>Updating TeleMetrum v1.x Firmware</title>
3087 <orderedlist inheritnum='inherit' numeration='arabic'>
3090 Find the 'programming cable' that you got as part of the starter
3091 kit, that has a red 8-pin MicroMaTch connector on one end and a
3092 red 4-pin MicroMaTch connector on the other end.
3097 Take the 2 screws out of the TeleDongle case to get access
3098 to the circuit board.
3103 Plug the 8-pin end of the programming cable to the
3104 matching connector on the TeleDongle, and the 4-pin end to the
3105 matching connector on the TeleMetrum.
3106 Note that each MicroMaTch connector has an alignment pin that
3107 goes through a hole in the PC board when you have the cable
3113 Attach a battery to the TeleMetrum board.
3118 Plug the TeleDongle into your computer's USB port, and power
3124 Run AltosUI, and select 'Flash Image' from the File menu.
3129 Pick the TeleDongle device from the list, identifying it as the
3135 Select the image you want put on the TeleMetrum, which should have a
3136 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
3137 in the default directory, if not you may have to poke around
3138 your system to find it.
3143 Make sure the configuration parameters are reasonable
3144 looking. If the serial number and/or RF configuration
3145 values aren't right, you'll need to change them.
3150 Hit the 'OK' button and the software should proceed to flash
3151 the TeleMetrum with new firmware, showing a progress bar.
3156 Confirm that the TeleMetrum board seems to have updated OK, which you
3157 can do by plugging in to it over USB and using a terminal program
3158 to connect to the board and issue the 'v' command to check
3164 If something goes wrong, give it another try.
3170 <title>Updating TeleMini Firmware</title>
3171 <orderedlist inheritnum='inherit' numeration='arabic'>
3174 You'll need a special 'programming cable' to reprogram the
3175 TeleMini. You can make your own using an 8-pin MicroMaTch
3176 connector on one end and a set of four pins on the other.
3181 Take the 2 screws out of the TeleDongle case to get access
3182 to the circuit board.
3187 Plug the 8-pin end of the programming cable to the matching
3188 connector on the TeleDongle, and the 4-pins into the holes
3189 in the TeleMini circuit board. Note that the MicroMaTch
3190 connector has an alignment pin that goes through a hole in
3191 the PC board when you have the cable oriented correctly, and
3192 that pin 1 on the TeleMini board is marked with a square pad
3193 while the other pins have round pads.
3198 Attach a battery to the TeleMini board.
3203 Plug the TeleDongle into your computer's USB port, and power
3209 Run AltosUI, and select 'Flash Image' from the File menu.
3214 Pick the TeleDongle device from the list, identifying it as the
3220 Select the image you want put on the TeleMini, which should have a
3221 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
3222 in the default directory, if not you may have to poke around
3223 your system to find it.
3228 Make sure the configuration parameters are reasonable
3229 looking. If the serial number and/or RF configuration
3230 values aren't right, you'll need to change them.
3235 Hit the 'OK' button and the software should proceed to flash
3236 the TeleMini with new firmware, showing a progress bar.
3241 Confirm that the TeleMini board seems to have updated OK, which you
3242 can do by configuring it over the radio link through the TeleDongle, or
3243 letting it come up in “flight” mode and listening for telemetry.
3248 If something goes wrong, give it another try.
3254 <title>Updating TeleDongle Firmware</title>
3256 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
3257 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
3259 <orderedlist inheritnum='inherit' numeration='arabic'>
3262 Find the 'programming cable' that you got as part of the starter
3263 kit, that has a red 8-pin MicroMaTch connector on one end and a
3264 red 4-pin MicroMaTch connector on the other end.
3269 Find the USB cable that you got as part of the starter kit, and
3270 plug the “mini” end in to the mating connector on TeleMetrum or TeleDongle.
3275 Take the 2 screws out of the TeleDongle case to get access
3276 to the circuit board.
3281 Plug the 8-pin end of the programming cable to the
3282 matching connector on the programmer, and the 4-pin end to the
3283 matching connector on the TeleDongle.
3284 Note that each MicroMaTch connector has an alignment pin that
3285 goes through a hole in the PC board when you have the cable
3291 Attach a battery to the TeleMetrum board if you're using one.
3296 Plug both the programmer and the TeleDongle into your computer's USB
3297 ports, and power up the programmer.
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