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5 <title>The Altus Metrum System</title>
6 <subtitle>An Owner's Manual for Altus Metrum Rocketry Electronics</subtitle>
9 <firstname>Bdale</firstname>
10 <surname>Garbee</surname>
13 <firstname>Keith</firstname>
14 <surname>Packard</surname>
17 <firstname>Bob</firstname>
18 <surname>Finch</surname>
21 <firstname>Anthony</firstname>
22 <surname>Towns</surname>
26 <holder>Bdale Garbee and Keith Packard</holder>
30 This document is released under the terms of the
31 <ulink url="http://creativecommons.org/licenses/by-sa/3.0/">
32 Creative Commons ShareAlike 3.0
39 <revnumber>1.3</revnumber>
40 <date>12 November 2013</date>
42 Updated for software version 1.3. Version 1.3 adds support
43 for TeleMega, TeleMetrum v2.0, TeleMini v2.0 and EasyMini
44 and fixes bugs in AltosUI and the AltOS firmware.
48 <revnumber>1.2.1</revnumber>
49 <date>21 May 2013</date>
51 Updated for software version 1.2. Version 1.2 adds support
52 for TeleBT and AltosDroid. It also adds a few minor features
53 and fixes bugs in AltosUI and the AltOS firmware.
57 <revnumber>1.2</revnumber>
58 <date>18 April 2013</date>
60 Updated for software version 1.2. Version 1.2 adds support
61 for MicroPeak and the MicroPeak USB interface.
65 <revnumber>1.1.1</revnumber>
66 <date>16 September 2012</date>
68 Updated for software version 1.1.1 Version 1.1.1 fixes a few
69 bugs found in version 1.1.
73 <revnumber>1.1</revnumber>
74 <date>13 September 2012</date>
76 Updated for software version 1.1. Version 1.1 has new
77 features but is otherwise compatible with version 1.0.
81 <revnumber>1.0</revnumber>
82 <date>24 August 2011</date>
84 Updated for software version 1.0. Note that 1.0 represents a
85 telemetry format change, meaning both ends of a link
86 (TeleMetrum/TeleMini and TeleDongle) must be updated or
87 communications will fail.
91 <revnumber>0.9</revnumber>
92 <date>18 January 2011</date>
94 Updated for software version 0.9. Note that 0.9 represents a
95 telemetry format change, meaning both ends of a link (TeleMetrum and
96 TeleDongle) must be updated or communications will fail.
100 <revnumber>0.8</revnumber>
101 <date>24 November 2010</date>
102 <revremark>Updated for software version 0.8 </revremark>
107 <title>Acknowledgements</title>
109 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing “The
110 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
111 Kit” which formed the basis of the original Getting Started chapter
112 in this manual. Bob was one of our first customers for a production
113 TeleMetrum, and his continued enthusiasm and contributions
114 are immensely gratifying and highly appreciated!
117 And thanks to Anthony (AJ) Towns for major contributions including
118 the AltosUI graphing and site map code and associated documentation.
119 Free software means that our customers and friends can become our
120 collaborators, and we certainly appreciate this level of
124 Have fun using these products, and we hope to meet all of you
125 out on the rocket flight line somewhere.
128 NAR #87103, TRA #12201
130 Keith Packard, KD7SQG
131 NAR #88757, TRA #12200
136 <title>Introduction and Overview</title>
138 Welcome to the Altus Metrum community! Our circuits and software reflect
139 our passion for both hobby rocketry and Free Software. We hope their
140 capabilities and performance will delight you in every way, but by
141 releasing all of our hardware and software designs under open licenses,
142 we also hope to empower you to take as active a role in our collective
146 The first device created for our community was TeleMetrum, a dual
147 deploy altimeter with fully integrated GPS and radio telemetry
148 as standard features, and a “companion interface” that will
149 support optional capabilities in the future. The latest version
150 of TeleMetrum, v2.0, has all of the same features but with
151 improved sensors and radio to offer increased performance.
154 Our second device was TeleMini, a dual deploy altimeter with
155 radio telemetry and radio direction finding. The first version
156 of this device was only 13mm by 38mm (½ inch by 1½ inches) and
157 could fit easily in an 18mm air-frame. The latest version, v2.0,
158 includes a beeper, USB data download and extended on-board
159 flight logging, along with an improved barometric sensor.
162 TeleMega is our most sophisticated device, including six pyro
163 channels (four of which are fully programmable), integrated GPS,
164 integrated gyroscopes for staging/air-start inhibit and high
165 performance telemetry.
168 EasyMini is a dual-deploy altimeter with logging and built-in
172 TeleDongle was our first ground station, providing a USB to RF
173 interfaces for communicating with the altimeters. Combined with
174 your choice of antenna and notebook computer, TeleDongle and our
175 associated user interface software form a complete ground
176 station capable of logging and displaying in-flight telemetry,
177 aiding rocket recovery, then processing and archiving flight
178 data for analysis and review.
181 For a slightly more portable ground station experience that also
182 provides direct rocket recovery support, TeleBT offers flight
183 monitoring and data logging using a Bluetooth connection between
184 the receiver and an Android device that has the Altos Droid
185 application installed from the Google Play store.
188 More products will be added to the Altus Metrum family over time, and
189 we currently envision that this will be a single, comprehensive manual
190 for the entire product family.
194 <title>Getting Started</title>
196 The first thing to do after you check the inventory of parts in your
197 “starter kit” is to charge the battery.
200 For TeleMetrum and TeleMega, the battery can be charged by plugging it into the
201 corresponding socket of the device and then using the USB
202 cable to plug the flight computer into your computer's USB socket. The
203 on-board circuitry will charge the battery whenever it is plugged
204 in, because the on-off switch does NOT control the
208 On TeleMetrum v1 boards, when the GPS chip is initially
209 searching for satellites, TeleMetrum will consume more current
210 than it can pull from the USB port, so the battery must be
211 attached in order to get satellite lock. Once GPS is locked,
212 the current consumption goes back down enough to enable charging
213 while running. So it's a good idea to fully charge the battery
214 as your first item of business so there is no issue getting and
215 maintaining satellite lock. The yellow charge indicator led
216 will go out when the battery is nearly full and the charger goes
217 to trickle charge. It can take several hours to fully recharge a
218 deeply discharged battery.
221 TeleMetrum v2.0 and TeleMega use a higher power battery charger,
222 allowing them to charge the battery while running the board at
223 maximum power. When the battery is charging, or when the board
224 is consuming a lot of power, the red LED will be lit. When the
225 battery is fully charged, the green LED will be lit. When the
226 battery is damaged or missing, both LEDs will be lit, which
230 The Lithium Polymer TeleMini and EasyMini battery can be charged by
231 disconnecting it from the board and plugging it into a
232 standalone battery charger such as the LipoCharger product
233 included in TeleMini Starter Kits, and connecting that via a USB
234 cable to a laptop or other USB power source.
237 You can also choose to use another battery with TeleMini v2.0
238 and EasyMini, anything supplying between 4 and 12 volts should
239 work fine (like a standard 9V battery), but if you are planning
240 to fire pyro charges, ground testing is required to verify that
241 the battery supplies enough current.
244 The other active device in the starter kit is the TeleDongle USB to
245 RF interface. If you plug it in to your Mac or Linux computer it should
246 “just work”, showing up as a serial port device. Windows systems need
247 driver information that is part of the AltOS download to know that the
248 existing USB modem driver will work. We therefore recommend installing
249 our software before plugging in TeleDongle if you are using a Windows
250 computer. If you are using Linux and are having problems, try moving
251 to a fresher kernel (2.6.33 or newer), as the USB serial driver had
252 ugly bugs in some earlier versions.
255 Next you should obtain and install the AltOS software. These
256 include the AltosUI ground station program, current firmware
257 images for all of the hardware, and a number of standalone
258 utilities that are rarely needed. Pre-built binary packages are
259 available for Linux, Microsoft Windows, and recent MacOSX
260 versions. Full source code and build instructions are also
261 available. The latest version may always be downloaded from
262 <ulink url="http://altusmetrum.org/AltOS"/>.
265 If you're using a TeleBT instead of the TeleDongle, you'll want
266 to go install the Altos Droid application from the Google Play
267 store. You don't need a data plan to use Altos Droid, but
268 without network access, the Map view will be less useful as it
269 won't contain any map data. You can also use TeleBT connected
270 over USB with your laptop computer; it acts exactly like a
271 TeleDongle. Anywhere this manual talks about TeleDongle, you can
272 also read that as 'and TeleBT when connected via USB'.
276 <title>Handling Precautions</title>
278 All Altus Metrum products are sophisticated electronic devices.
279 When handled gently and properly installed in an air-frame, they
280 will deliver impressive results. However, as with all electronic
281 devices, there are some precautions you must take.
284 The Lithium Polymer rechargeable batteries have an
285 extraordinary power density. This is great because we can fly with
286 much less battery mass than if we used alkaline batteries or previous
287 generation rechargeable batteries... but if they are punctured
288 or their leads are allowed to short, they can and will release their
290 Thus we recommend that you take some care when handling our batteries
291 and consider giving them some extra protection in your air-frame. We
292 often wrap them in suitable scraps of closed-cell packing foam before
293 strapping them down, for example.
296 The barometric sensors used on all of our flight computers are
297 sensitive to sunlight. In normal mounting situations, the baro sensor
298 and all of the other surface mount components
299 are “down” towards whatever the underlying mounting surface is, so
300 this is not normally a problem. Please consider this, though, when
301 designing an installation, for example, in an air-frame with a
302 see-through plastic payload bay. It is particularly important to
303 consider this with TeleMini v1.0, both because the baro sensor is on the
304 “top” of the board, and because many model rockets with payload bays
305 use clear plastic for the payload bay! Replacing these with an opaque
306 cardboard tube, painting them, or wrapping them with a layer of masking
307 tape are all reasonable approaches to keep the sensor out of direct
311 The barometric sensor sampling port must be able to “breathe”,
312 both by not being covered by foam or tape or other materials that might
313 directly block the hole on the top of the sensor, and also by having a
314 suitable static vent to outside air.
317 As with all other rocketry electronics, Altus Metrum altimeters must
318 be protected from exposure to corrosive motor exhaust and ejection
323 <title>Altus Metrum Hardware</title>
325 <title>Overview</title>
327 Here's the full set of Altus Metrum products, both in
328 production and retired.
331 <title>Altus Metrum Electronics</title>
332 <tgroup cols='8' align='center' colsep='1' rowsep='1'>
333 <colspec align='center' colwidth='*' colname='Device'/>
334 <colspec align='center' colwidth='*' colname='Barometer'/>
335 <colspec align='center' colwidth='*' colname='Z-axis accelerometer'/>
336 <colspec align='center' colwidth='*' colname='GPS'/>
337 <colspec align='center' colwidth='*' colname='3D sensors'/>
338 <colspec align='center' colwidth='*' colname='Storage'/>
339 <colspec align='center' colwidth='*' colname='RF'/>
340 <colspec align='center' colwidth='*' colname='Battery'/>
343 <entry align='center'>Device</entry>
344 <entry align='center'>Barometer</entry>
345 <entry align='center'>Z-axis accelerometer</entry>
346 <entry align='center'>GPS</entry>
347 <entry align='center'>3D sensors</entry>
348 <entry align='center'>Storage</entry>
349 <entry align='center'>RF Output</entry>
350 <entry align='center'>Battery</entry>
355 <entry>TeleMetrum v1.0</entry>
356 <entry><para>MP3H6115 10km (33k')</para></entry>
357 <entry><para>MMA2202 50g</para></entry>
358 <entry>SkyTraq</entry>
365 <entry>TeleMetrum v1.1</entry>
366 <entry><para>MP3H6115 10km (33k')</para></entry>
367 <entry><para>MMA2202 50g</para></entry>
368 <entry>SkyTraq</entry>
375 <entry>TeleMetrum v1.2</entry>
376 <entry><para>MP3H6115 10km (33k')</para></entry>
377 <entry><para>ADXL78 70g</para></entry>
378 <entry>SkyTraq</entry>
385 <entry>TeleMetrum v2.0</entry>
386 <entry><para>MS5607 30km (100k')</para></entry>
387 <entry><para>MMA6555 102g</para></entry>
388 <entry>uBlox Max-7Q</entry>
395 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
396 <entry><para>MP3H6115 10km (33k')</para></entry>
405 <entry>TeleMini <?linebreak?>v2.0</entry>
406 <entry><para>MS5607 30km (100k')</para></entry>
412 <entry>3.7-12V</entry>
415 <entry>EasyMini <?linebreak?>v1.0</entry>
416 <entry><para>MS5607 30km (100k')</para></entry>
422 <entry>3.7-12V</entry>
425 <entry>TeleMega <?linebreak?>v1.0</entry>
426 <entry><para>MS5607 30km (100k')</para></entry>
427 <entry><para>MMA6555 102g</para></entry>
428 <entry>uBlox Max-7Q</entry>
429 <entry><para>MPU6000 HMC5883</para></entry>
438 <title>Altus Metrum Boards</title>
439 <tgroup cols='6' align='center' colsep='1' rowsep='1'>
440 <colspec align='center' colwidth='*' colname='Device'/>
441 <colspec align='center' colwidth='*' colname='Connectors'/>
442 <colspec align='center' colwidth='*' colname='Screw Terminals'/>
443 <colspec align='center' colwidth='*' colname='Width'/>
444 <colspec align='center' colwidth='*' colname='Length'/>
445 <colspec align='center' colwidth='*' colname='Tube Size'/>
448 <entry align='center'>Device</entry>
449 <entry align='center'>Connectors</entry>
450 <entry align='center'>Screw Terminals</entry>
451 <entry align='center'>Width</entry>
452 <entry align='center'>Length</entry>
453 <entry align='center'>Tube Size</entry>
458 <entry>TeleMetrum</entry>
462 Companion<?linebreak?>
466 <entry><para>Apogee pyro <?linebreak?>Main pyro <?linebreak?>Switch</para></entry>
467 <entry>1 inch (2.54cm)</entry>
468 <entry>2 ¾ inch (6.99cm)</entry>
469 <entry>29mm coupler</entry>
472 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
479 Apogee pyro <?linebreak?>
482 <entry>½ inch (1.27cm)</entry>
483 <entry>1½ inch (3.81cm)</entry>
484 <entry>18mm aiframe</entry>
487 <entry>TeleMini <?linebreak?>v2.0</entry>
495 Apogee pyro <?linebreak?>
496 Main pyro <?linebreak?>
497 Battery <?linebreak?>
500 <entry>0.8 inch (2.03cm)</entry>
501 <entry>1½ inch (3.81cm)</entry>
502 <entry>24mm coupler</entry>
505 <entry>EasyMini</entry>
512 Apogee pyro <?linebreak?>
513 Main pyro <?linebreak?>
514 Battery <?linebreak?>
517 <entry>0.8 inch (2.03cm)</entry>
518 <entry>1½ inch (3.81cm)</entry>
519 <entry>24mm coupler</entry>
522 <entry>TeleMega</entry>
526 Companion<?linebreak?>
531 Apogee pyro <?linebreak?>
532 Main pyro<?linebreak?>
533 Pyro A-D<?linebreak?>
537 <entry>1¼ inch (3.18cm)</entry>
538 <entry>3¼ inch (8.26cm)</entry>
539 <entry>38mm coupler</entry>
546 <title>TeleMetrum</title>
548 TeleMetrum is a 1 inch by 2¾ inch circuit board. It was designed to
549 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
550 small in diameter may require some creativity in mounting and wiring
551 to succeed! The presence of an accelerometer means TeleMetrum should
552 be aligned along the flight axis of the airframe, and by default the ¼
553 wave UHF wire antenna should be on the nose-cone end of the board. The
554 antenna wire is about 7 inches long, and wiring for a power switch and
555 the e-matches for apogee and main ejection charges depart from the
556 fin can end of the board, meaning an ideal “simple” avionics
557 bay for TeleMetrum should have at least 10 inches of interior length.
561 <title>TeleMini</title>
563 TeleMini v1.0 is ½ inches by 1½ inches. It was
564 designed to fit inside an 18mm air-frame tube, but using it in
565 a tube that small in diameter may require some creativity in
566 mounting and wiring to succeed! Since there is no
567 accelerometer, TeleMini can be mounted in any convenient
568 orientation. The default ¼ wave UHF wire antenna attached to
569 the center of one end of the board is about 7 inches long. Two
570 wires for the power switch are connected to holes in the
571 middle of the board. Screw terminals for the e-matches for
572 apogee and main ejection charges depart from the other end of
573 the board, meaning an ideal “simple” avionics bay for TeleMini
574 should have at least 9 inches of interior length.
577 TeleMini v2.0 is 0.8 inches by 1½ inches. It adds more
578 on-board data logging memory, a built-in USB connector and
579 screw terminals for the battery and power switch. The larger
580 board fits in a 24mm coupler. There's also a battery connector
581 for a LiPo battery if you want to use one of those.
585 <title>EasyMini</title>
587 EasyMini is built on a 0.8 inch by 1½ inch circuit board. It's
588 designed to fit in a 24mm coupler tube. The connectors and
589 screw terminals match TeleMini, so you can swap an EasyMini
594 <title>TeleMega</title>
596 TeleMega is a 1¼ inch by 3¼ inch circuit board. It was
597 designed to easily fit in a 38mm coupler. Like TeleMetrum,
598 TeleMega has an accelerometer and so it must be mounted so that
599 the board is aligned with the flight axis. It can be mounted
600 either antenna up or down.
604 <title>Flight Data Recording</title>
606 Each flight computer logs data at 100 samples per second
607 during ascent and 10 samples per second during descent, except
608 for TeleMini v1.0, which records ascent at 10 samples per
609 second and descent at 1 sample per second. Data are logged to
610 an on-board flash memory part, which can be partitioned into
611 several equal-sized blocks, one for each flight.
614 <title>Data Storage on Altus Metrum altimeters</title>
615 <tgroup cols='4' align='center' colsep='1' rowsep='1'>
616 <colspec align='center' colwidth='*' colname='Device'/>
617 <colspec align='center' colwidth='*' colname='Bytes per sample'/>
618 <colspec align='center' colwidth='*' colname='Total storage'/>
619 <colspec align='center' colwidth='*' colname='Minutes of
623 <entry align='center'>Device</entry>
624 <entry align='center'>Bytes per Sample</entry>
625 <entry align='center'>Total Storage</entry>
626 <entry align='center'>Minutes at Full Rate</entry>
631 <entry>TeleMetrum v1.0</entry>
637 <entry>TeleMetrum v1.1 v1.2</entry>
643 <entry>TeleMetrum v2.0</entry>
649 <entry>TeleMini v1.0</entry>
655 <entry>TeleMini v2.0</entry>
661 <entry>EasyMini</entry>
667 <entry>TeleMega</entry>
676 The on-board flash is partitioned into separate flight logs,
677 each of a fixed maximum size. Increase the maximum size of
678 each log and you reduce the number of flights that can be
679 stored. Decrease the size and you can store more flights.
682 Configuration data is also stored in the flash memory on
683 TeleMetrum v1.x, TeleMini and EasyMini. This consumes 64kB
684 of flash space. This configuration space is not available
685 for storing flight log data. TeleMetrum v2.0 and TeleMega
686 store configuration data in a bit of eeprom available within
687 the processor chip, leaving that space available in flash for
691 To compute the amount of space needed for a single flight, you
692 can multiply the expected ascent time (in seconds) by 100
693 times bytes-per-sample, multiply the expected descent time (in
694 seconds) by 10 times the bytes per sample and add the two
695 together. That will slightly under-estimate the storage (in
696 bytes) needed for the flight. For instance, a TeleMetrum v2.0 flight spending
697 20 seconds in ascent and 150 seconds in descent will take
698 about (20 * 1600) + (150 * 160) = 56000 bytes of storage. You
699 could store dozens of these flights in the on-board flash.
702 The default size allows for several flights on each flight
703 computer, except for TeleMini v1.0, which only holds data for a
704 single flight. You can adjust the size.
707 Altus Metrum flight computers will not overwrite existing
708 flight data, so be sure to download flight data and erase it
709 from the flight computer before it fills up. The flight
710 computer will still successfully control the flight even if it
711 cannot log data, so the only thing you will lose is the data.
715 <title>Installation</title>
717 A typical installation involves attaching
718 only a suitable battery, a single pole switch for
719 power on/off, and two pairs of wires connecting e-matches for the
720 apogee and main ejection charges. All Altus Metrum products are
721 designed for use with single-cell batteries with 3.7 volts
722 nominal. TeleMini v2.0 and EasyMini may also be used with other
723 batteries as long as they supply between 4 and 12 volts.
726 The battery connectors are a standard 2-pin JST connector and
727 match batteries sold by Spark Fun. These batteries are
728 single-cell Lithium Polymer batteries that nominally provide 3.7
729 volts. Other vendors sell similar batteries for RC aircraft
730 using mating connectors, however the polarity for those is
731 generally reversed from the batteries used by Altus Metrum
732 products. In particular, the Tenergy batteries supplied for use
733 in Featherweight flight computers are not compatible with Altus
734 Metrum flight computers or battery chargers. <emphasis>Check
735 polarity and voltage before connecting any battery not purchased
736 from Altus Metrum or Spark Fun.</emphasis>
739 By default, we use the unregulated output of the battery directly
740 to fire ejection charges. This works marvelously with standard
741 low-current e-matches like the J-Tek from MJG Technologies, and with
742 Quest Q2G2 igniters. However, if you want or need to use a separate
743 pyro battery, check out the “External Pyro Battery” section in this
744 manual for instructions on how to wire that up. The altimeters are
745 designed to work with an external pyro battery of no more than 15 volts.
749 Ejection charges are wired directly to the screw terminal block
750 at the aft end of the altimeter. You'll need a very small straight
751 blade screwdriver for these screws, such as you might find in a
752 jeweler's screwdriver set.
755 Except for TeleMini v1.0, the flight computers also use the
756 screw terminal block for the power switch leads. On TeleMini v1.0,
757 the power switch leads are soldered directly to the board and
758 can be connected directly to a switch.
761 For most air-frames, the integrated antennas are more than
762 adequate. However, if you are installing in a carbon-fiber or
763 metal electronics bay which is opaque to RF signals, you may need to
764 use off-board external antennas instead. In this case, you can
765 order an altimeter with an SMA connector for the UHF antenna
766 connection, and, on TeleMetrum v1, you can unplug the integrated GPS
767 antenna and select an appropriate off-board GPS antenna with
768 cable terminating in a U.FL connector.
773 <title>System Operation</title>
775 <title>Firmware Modes </title>
777 The AltOS firmware build for the altimeters has two
778 fundamental modes, “idle” and “flight”. Which of these modes
779 the firmware operates in is determined at start up time. For
780 TeleMetrum, the mode is controlled by the orientation of the
781 rocket (well, actually the board, of course...) at the time
782 power is switched on. If the rocket is “nose up”, then
783 TeleMetrum assumes it's on a rail or rod being prepared for
784 launch, so the firmware chooses flight mode. However, if the
785 rocket is more or less horizontal, the firmware instead enters
786 idle mode. Since TeleMini v2.0 and EasyMini don't have an
787 accelerometer we can use to determine orientation, “idle” mode
788 is selected if the board is connected via USB to a computer,
789 otherwise the board enters “flight” mode. TeleMini v1.0
790 selects “idle” mode if it receives a command packet within the
791 first five seconds of operation.
794 At power on, you will hear three beeps or see three flashes
795 (“S” in Morse code for start up) and then a pause while
796 the altimeter completes initialization and self test, and decides
797 which mode to enter next.
800 In flight or “pad” mode, the altimeter engages the flight
801 state machine, goes into transmit-only mode to
802 send telemetry, and waits for launch to be detected.
803 Flight mode is indicated by an “di-dah-dah-dit” (“P” for pad)
804 on the beeper or lights, followed by beeps or flashes
805 indicating the state of the pyrotechnic igniter continuity.
806 One beep/flash indicates apogee continuity, two beeps/flashes
807 indicate main continuity, three beeps/flashes indicate both
808 apogee and main continuity, and one longer “brap” sound or
809 rapidly alternating lights indicates no continuity. For a
810 dual deploy flight, make sure you're getting three beeps or
811 flashes before launching! For apogee-only or motor eject
812 flights, do what makes sense.
815 If idle mode is entered, you will hear an audible “di-dit” or
816 see two short flashes (“I” for idle), and the flight state
817 machine is disengaged, thus no ejection charges will fire.
818 The altimeters also listen for the radio link when in idle
819 mode for requests sent via TeleDongle. Commands can be issued
820 in idle mode over either USB or the radio link
821 equivalently. TeleMini v1.0 only has the radio link. Idle
822 mode is useful for configuring the altimeter, for extracting
823 data from the on-board storage chip after flight, and for
824 ground testing pyro charges.
827 One “neat trick” of particular value when TeleMetrum or TeleMega are used with
828 very large air-frames, is that you can power the board up while the
829 rocket is horizontal, such that it comes up in idle mode. Then you can
830 raise the air-frame to launch position, and issue a 'reset' command
831 via TeleDongle over the radio link to cause the altimeter to reboot and
832 come up in flight mode. This is much safer than standing on the top
833 step of a rickety step-ladder or hanging off the side of a launch
834 tower with a screw-driver trying to turn on your avionics before
838 TeleMini v1.0 is configured solely via the radio link. Of course, that
839 means you need to know the TeleMini radio configuration values
840 or you won't be able to communicate with it. For situations
841 when you don't have the radio configuration values, TeleMini v1.0
842 offers an 'emergency recovery' mode. In this mode, TeleMini is
843 configured as follows:
847 Sets the radio frequency to 434.550MHz
852 Sets the radio calibration back to the factory value.
857 Sets the callsign to N0CALL
862 Does not go to 'pad' mode after five seconds.
868 To get into 'emergency recovery' mode, first find the row of
869 four small holes opposite the switch wiring. Using a short
870 piece of small gauge wire, connect the outer two holes
871 together, then power TeleMini up. Once the red LED is lit,
872 disconnect the wire and the board should signal that it's in
873 'idle' mode after the initial five second startup period.
879 TeleMetrum and TeleMega include a complete GPS receiver. A
880 complete explanation of how GPS works is beyond the scope of
881 this manual, but the bottom line is that the GPS receiver
882 needs to lock onto at least four satellites to obtain a solid
883 3 dimensional position fix and know what time it is.
886 The flight computers provide backup power to the GPS chip any time a
887 battery is connected. This allows the receiver to “warm start” on
888 the launch rail much faster than if every power-on were a GPS
889 “cold start”. In typical operations, powering up
890 on the flight line in idle mode while performing final air-frame
891 preparation will be sufficient to allow the GPS receiver to cold
892 start and acquire lock. Then the board can be powered down during
893 RSO review and installation on a launch rod or rail. When the board
894 is turned back on, the GPS system should lock very quickly, typically
895 long before igniter installation and return to the flight line are
900 <title>Controlling An Altimeter Over The Radio Link</title>
902 One of the unique features of the Altus Metrum system is the
903 ability to create a two way command link between TeleDongle
904 and an altimeter using the digital radio transceivers
905 built into each device. This allows you to interact with the
906 altimeter from afar, as if it were directly connected to the
910 Any operation which can be performed with a flight computer can
911 either be done with the device directly connected to the
912 computer via the USB cable, or through the radio
913 link. TeleMini v1.0 doesn't provide a USB connector and so it is
914 always communicated with over radio. Select the appropriate
915 TeleDongle device when the list of devices is presented and
916 AltosUI will interact with an altimeter over the radio link.
919 One oddity in the current interface is how AltosUI selects the
920 frequency for radio communications. Instead of providing
921 an interface to specifically configure the frequency, it uses
922 whatever frequency was most recently selected for the target
923 TeleDongle device in Monitor Flight mode. If you haven't ever
924 used that mode with the TeleDongle in question, select the
925 Monitor Flight button from the top level UI, and pick the
926 appropriate TeleDongle device. Once the flight monitoring
927 window is open, select the desired frequency and then close it
928 down again. All radio communications will now use that frequency.
933 Save Flight Data—Recover flight data from the rocket without
939 Configure altimeter apogee delays, main deploy heights
940 and additional pyro event conditions
941 to respond to changing launch conditions. You can also
942 'reboot' the altimeter. Use this to remotely enable the
943 flight computer by turning TeleMetrum or TeleMega on in “idle” mode,
944 then once the air-frame is oriented for launch, you can
945 reboot the altimeter and have it restart in pad mode
946 without having to climb the scary ladder.
951 Fire Igniters—Test your deployment charges without snaking
952 wires out through holes in the air-frame. Simply assemble the
953 rocket as if for flight with the apogee and main charges
954 loaded, then remotely command the altimeter to fire the
960 Operation over the radio link for configuring an altimeter, ground
961 testing igniters, and so forth uses the same RF frequencies as flight
962 telemetry. To configure the desired TeleDongle frequency, select
963 the monitor flight tab, then use the frequency selector and
964 close the window before performing other desired radio operations.
967 The flight computers only enable radio commanding in 'idle' mode.
968 TeleMetrum and TeleMega use the accelerometer to detect which orientation they
969 start up in, so make sure you have the flight computer lying horizontally when you turn
970 it on. Otherwise, it will start in 'pad' mode ready for
971 flight, and will not be listening for command packets from TeleDongle.
974 TeleMini listens for a command packet for five seconds after
975 first being turned on, if it doesn't hear anything, it enters
976 'pad' mode, ready for flight and will no longer listen for
977 command packets. The easiest way to connect to TeleMini is to
978 initiate the command and select the TeleDongle device. At this
979 point, the TeleDongle will be attempting to communicate with
980 the TeleMini. Now turn TeleMini on, and it should immediately
981 start communicating with the TeleDongle and the desired
982 operation can be performed.
985 You can monitor the operation of the radio link by watching the
986 lights on the devices. The red LED will flash each time a packet
987 is transmitted, while the green LED will light up on TeleDongle when
988 it is waiting to receive a packet from the altimeter.
992 <title>Ground Testing </title>
994 An important aspect of preparing a rocket using electronic deployment
995 for flight is ground testing the recovery system. Thanks
996 to the bi-directional radio link central to the Altus Metrum system,
997 this can be accomplished in a TeleMega, TeleMetrum or TeleMini equipped rocket
998 with less work than you may be accustomed to with other systems. It
1002 Just prep the rocket for flight, then power up the altimeter
1003 in “idle” mode (placing air-frame horizontal for TeleMetrum or TeleMega, or
1004 selecting the Configure Altimeter tab for TeleMini). This will cause
1005 the firmware to go into “idle” mode, in which the normal flight
1006 state machine is disabled and charges will not fire without
1007 manual command. You can now command the altimeter to fire the apogee
1008 or main charges from a safe distance using your computer and
1009 TeleDongle and the Fire Igniter tab to complete ejection testing.
1013 <title>Radio Link </title>
1015 The chip our boards are based on incorporates an RF transceiver, but
1016 it's not a full duplex system... each end can only be transmitting or
1017 receiving at any given moment. So we had to decide how to manage the
1021 By design, the altimeter firmware listens for the radio link when
1022 it's in “idle mode”, which
1023 allows us to use the radio link to configure the rocket, do things like
1024 ejection tests, and extract data after a flight without having to
1025 crack open the air-frame. However, when the board is in “flight
1026 mode”, the altimeter only
1027 transmits and doesn't listen at all. That's because we want to put
1028 ultimate priority on event detection and getting telemetry out of
1030 the radio in case the rocket crashes and we aren't able to extract
1034 We don't generally use a 'normal packet radio' mode like APRS
1035 because they're just too inefficient. The GFSK modulation we
1036 use is FSK with the base-band pulses passed through a Gaussian
1037 filter before they go into the modulator to limit the
1038 transmitted bandwidth. When combined with forward error
1039 correction and interleaving, this allows us to have a very
1040 robust 19.2 kilobit data link with only 10-40 milliwatts of
1041 transmit power, a whip antenna in the rocket, and a hand-held
1042 Yagi on the ground. We've had flights to above 21k feet AGL
1043 with great reception, and calculations suggest we should be
1044 good to well over 40k feet AGL with a 5-element yagi on the
1045 ground with our 10mW units and over 100k feet AGL with the
1046 40mW devices. We hope to fly boards to higher altitudes over
1047 time, and would of course appreciate customer feedback on
1048 performance in higher altitude flights!
1051 TeleMetrum v2.0 and TeleMega can send APRS if desired, the
1052 interval between APRS packets can be configured. As each APRS
1053 packet takes a full second to transmit, we recommend an
1054 interval of at least 5 seconds to avoid consuming too much
1055 battery power or radio channel bandwidth.
1059 <title>Configurable Parameters</title>
1061 Configuring an Altus Metrum altimeter for flight is very
1062 simple. Even on our baro-only TeleMini and EasyMini boards, the use of a Kalman
1063 filter means there is no need to set a “mach delay”. The few
1064 configurable parameters can all be set using AltosUI over USB or
1065 or radio link via TeleDongle.
1068 <title>Radio Frequency</title>
1070 Altus Metrum boards support radio frequencies in the 70cm
1071 band. By default, the configuration interface provides a
1072 list of 10 “standard” frequencies in 100kHz channels starting at
1073 434.550MHz. However, the firmware supports use of
1074 any 50kHz multiple within the 70cm band. At any given
1075 launch, we highly recommend coordinating when and by whom each
1076 frequency will be used to avoid interference. And of course, both
1077 altimeter and TeleDongle must be configured to the same
1078 frequency to successfully communicate with each other.
1082 <title>Apogee Delay</title>
1084 Apogee delay is the number of seconds after the altimeter detects flight
1085 apogee that the drogue charge should be fired. In most cases, this
1086 should be left at the default of 0. However, if you are flying
1087 redundant electronics such as for an L3 certification, you may wish
1088 to set one of your altimeters to a positive delay so that both
1089 primary and backup pyrotechnic charges do not fire simultaneously.
1092 The Altus Metrum apogee detection algorithm fires exactly at
1093 apogee. If you are also flying an altimeter like the
1094 PerfectFlite MAWD, which only supports selecting 0 or 1
1095 seconds of apogee delay, you may wish to set the MAWD to 0
1096 seconds delay and set the TeleMetrum to fire your backup 2
1097 or 3 seconds later to avoid any chance of both charges
1098 firing simultaneously. We've flown several air-frames this
1099 way quite happily, including Keith's successful L3 cert.
1103 <title>Main Deployment Altitude</title>
1105 By default, the altimeter will fire the main deployment charge at an
1106 elevation of 250 meters (about 820 feet) above ground. We think this
1107 is a good elevation for most air-frames, but feel free to change this
1108 to suit. In particular, if you are flying two altimeters, you may
1110 deployment elevation for the backup altimeter to be something lower
1111 than the primary so that both pyrotechnic charges don't fire
1116 <title>Maximum Flight Log</title>
1118 Changing this value will set the maximum amount of flight
1119 log storage that an individual flight will use. The
1120 available storage is divided into as many flights of the
1121 specified size as can fit in the available space. You can
1122 download and erase individual flight logs. If you fill up
1123 the available storage, future flights will not get logged
1124 until you erase some of the stored ones.
1128 <title>Ignite Mode</title>
1130 Instead of firing one charge at apogee and another charge at
1131 a fixed height above the ground, you can configure the
1132 altimeter to fire both at apogee or both during
1133 descent. This was added to support an airframe that has two
1134 altimeters, one in the fin can and one in the
1138 Providing the ability to use both igniters for apogee or
1139 main allows some level of redundancy without needing two
1140 flight computers. In Redundant Apogee or Redundant Main
1141 mode, the two charges will be fired two seconds apart.
1145 <title>Pad Orientation</title>
1147 TeleMetrum and TeleMega measure acceleration along the axis
1148 of the board. Which way the board is oriented affects the
1149 sign of the acceleration value. Instead of trying to guess
1150 which way the board is mounted in the air frame, the
1151 altimeter must be explicitly configured for either Antenna
1152 Up or Antenna Down. The default, Antenna Up, expects the end
1153 of the board connected to the 70cm antenna to be nearest the
1154 nose of the rocket, with the end containing the screw
1155 terminals nearest the tail.
1159 <title>Pyro Channels</title>
1161 In addition to the usual Apogee and Main pyro channels,
1162 TeleMega has four additional channels that can be configured
1163 to activate when various flight conditions are
1164 satisfied. You can select as many conditions as necessary;
1165 all of them must be met in order to activate the
1166 channel. The conditions available are:
1171 Acceleration away from the ground. Select a value, and
1172 then choose whether acceleration should be above or
1173 below that value. Acceleration is positive upwards, so
1174 accelerating towards the ground would produce negative
1175 numbers. Acceleration during descent is noisy and
1176 inaccurate, so be careful when using it during these
1177 phases of the flight.
1182 Vertical speed. Select a value, and then choose whether
1183 vertical speed should be above or below that
1184 value. Speed is positive upwards, so moving towards the
1185 ground would produce negative numbers. Speed during
1186 descent is a bit noisy and so be careful when using it
1187 during these phases of the flight.
1192 Height. Select a value, and then choose whether the
1193 height above the launch pad should be above or below
1199 Orientation. TeleMega contains a 3-axis gyroscope and
1200 accelerometer which is used to measure the current
1201 angle. Note that this angle is not the change in angle
1202 from the launch pad, but rather absolute relative to
1203 gravity; the 3-axis accelerometer is used to compute the
1204 angle of the rocket on the launch pad and initialize the
1205 system. Because this value is computed by integrating
1206 rate gyros, it gets progressively less accurate as the
1207 flight goes on. It should have an accumulated error of
1208 less than .2°/second (after 10 seconds of flight, the
1209 error should be less than 2°).
1212 The usual use of the orientation configuration is to
1213 ensure that the rocket is traveling mostly upwards when
1214 deciding whether to ignite air starts or additional
1215 stages. For that, choose a reasonable maximum angle
1216 (like 20°) and set the motor igniter to require an angle
1217 of less than that value.
1222 Flight Time. Time since boost was detected. Select a
1223 value and choose whether to activate the pyro channel
1224 before or after that amount of time.
1229 Ascending. A simple test saying whether the rocket is
1230 going up or not. This is exactly equivalent to testing
1231 whether the speed is > 0.
1236 Descending. A simple test saying whether the rocket is
1237 going down or not. This is exactly equivalent to testing
1238 whether the speed is < 0.
1243 After Motor. The flight software counts each time the
1244 rocket starts accelerating (presumably due to a motor or
1245 motors igniting). Use this value to count ignitions for
1246 multi-staged or multi-airstart launches.
1251 Delay. This value doesn't perform any checks, instead it
1252 inserts a delay between the time when the other
1253 parameters become true and when the pyro channel is
1259 Flight State. The flight software tracks the flight
1260 through a sequence of states:
1264 Boost. The motor has lit and the rocket is
1265 accelerating upwards.
1270 Fast. The motor has burned out and the rocket is
1271 descellerating, but it is going faster than 200m/s.
1276 Coast. The rocket is still moving upwards and
1277 decelerating, but the speed is less than 200m/s.
1282 Drogue. The rocket has reached apogee and is heading
1283 back down, but is above the configured Main
1289 Main. The rocket is still descending, and is blow
1295 Landed. The rocket is no longer moving.
1301 You can select a state to limit when the pyro channel
1302 may activate; note that the check is based on when the
1303 rocket transitions *into* the state, and so checking for
1304 'greater than Boost' means that the rocket is currently
1308 When a motor burns out, the rocket enters either Fast or
1309 Coast state (depending on how fast it is moving). If the
1310 computer detects upwards acceleration again, it will
1311 move back to Boost state.
1321 <title>AltosUI</title>
1323 The AltosUI program provides a graphical user interface for
1324 interacting with the Altus Metrum product family. AltosUI can
1325 monitor telemetry data, configure devices and many other
1326 tasks. The primary interface window provides a selection of
1327 buttons, one for each major activity in the system. This manual
1328 is split into chapters, each of which documents one of the tasks
1329 provided from the top-level toolbar.
1332 <title>Monitor Flight</title>
1333 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
1335 Selecting this item brings up a dialog box listing all of the
1336 connected TeleDongle devices. When you choose one of these,
1337 AltosUI will create a window to display telemetry data as
1338 received by the selected TeleDongle device.
1341 All telemetry data received are automatically recorded in
1342 suitable log files. The name of the files includes the current
1343 date and rocket serial and flight numbers.
1346 The radio frequency being monitored by the TeleDongle device is
1347 displayed at the top of the window. You can configure the
1348 frequency by clicking on the frequency box and selecting the desired
1349 frequency. AltosUI remembers the last frequency selected for each
1350 TeleDongle and selects that automatically the next time you use
1354 Below the TeleDongle frequency selector, the window contains a few
1355 significant pieces of information about the altimeter providing
1356 the telemetry data stream:
1360 <para>The configured call-sign</para>
1363 <para>The device serial number</para>
1366 <para>The flight number. Each altimeter remembers how many
1372 The rocket flight state. Each flight passes through several
1373 states including Pad, Boost, Fast, Coast, Drogue, Main and
1379 The Received Signal Strength Indicator value. This lets
1380 you know how strong a signal TeleDongle is receiving. The
1381 radio inside TeleDongle operates down to about -99dBm;
1382 weaker signals may not be receivable. The packet link uses
1383 error detection and correction techniques which prevent
1384 incorrect data from being reported.
1389 The age of the displayed data, in seconds since the last
1390 successfully received telemetry packet. In normal operation
1391 this will stay in the low single digits. If the number starts
1392 counting up, then you are no longer receiving data over the radio
1393 link from the flight computer.
1398 Finally, the largest portion of the window contains a set of
1399 tabs, each of which contain some information about the rocket.
1400 They're arranged in 'flight order' so that as the flight
1401 progresses, the selected tab automatically switches to display
1402 data relevant to the current state of the flight. You can select
1403 other tabs at any time. The final 'table' tab displays all of
1404 the raw telemetry values in one place in a spreadsheet-like format.
1407 <title>Launch Pad</title>
1409 The 'Launch Pad' tab shows information used to decide when the
1410 rocket is ready for flight. The first elements include red/green
1411 indicators, if any of these is red, you'll want to evaluate
1412 whether the rocket is ready to launch:
1416 Battery Voltage. This indicates whether the Li-Po battery
1417 powering the TeleMetrum has sufficient charge to last for
1418 the duration of the flight. A value of more than
1419 3.7V is required for a 'GO' status.
1424 Apogee Igniter Voltage. This indicates whether the apogee
1425 igniter has continuity. If the igniter has a low
1426 resistance, then the voltage measured here will be close
1427 to the Li-Po battery voltage. A value greater than 3.2V is
1428 required for a 'GO' status.
1433 Main Igniter Voltage. This indicates whether the main
1434 igniter has continuity. If the igniter has a low
1435 resistance, then the voltage measured here will be close
1436 to the Li-Po battery voltage. A value greater than 3.2V is
1437 required for a 'GO' status.
1442 On-board Data Logging. This indicates whether there is
1443 space remaining on-board to store flight data for the
1444 upcoming flight. If you've downloaded data, but failed
1445 to erase flights, there may not be any space
1446 left. TeleMetrum can store multiple flights, depending
1447 on the configured maximum flight log size. TeleMini
1448 stores only a single flight, so it will need to be
1449 downloaded and erased after each flight to capture
1450 data. This only affects on-board flight logging; the
1451 altimeter will still transmit telemetry and fire
1452 ejection charges at the proper times.
1457 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
1458 currently able to compute position information. GPS requires
1459 at least 4 satellites to compute an accurate position.
1464 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
1465 10 consecutive positions without losing lock. This ensures
1466 that the GPS receiver has reliable reception from the
1473 The Launchpad tab also shows the computed launch pad position
1474 and altitude, averaging many reported positions to improve the
1475 accuracy of the fix.
1479 <title>Ascent</title>
1481 This tab is shown during Boost, Fast and Coast
1482 phases. The information displayed here helps monitor the
1483 rocket as it heads towards apogee.
1486 The height, speed and acceleration are shown along with the
1487 maximum values for each of them. This allows you to quickly
1488 answer the most commonly asked questions you'll hear during
1492 The current latitude and longitude reported by the TeleMetrum GPS are
1493 also shown. Note that under high acceleration, these values
1494 may not get updated as the GPS receiver loses position
1495 fix. Once the rocket starts coasting, the receiver should
1496 start reporting position again.
1499 Finally, the current igniter voltages are reported as in the
1500 Launch Pad tab. This can help diagnose deployment failures
1501 caused by wiring which comes loose under high acceleration.
1505 <title>Descent</title>
1507 Once the rocket has reached apogee and (we hope) activated the
1508 apogee charge, attention switches to tracking the rocket on
1509 the way back to the ground, and for dual-deploy flights,
1510 waiting for the main charge to fire.
1513 To monitor whether the apogee charge operated correctly, the
1514 current descent rate is reported along with the current
1515 height. Good descent rates vary based on the choice of recovery
1516 components, but generally range from 15-30m/s on drogue and should
1517 be below 10m/s when under the main parachute in a dual-deploy flight.
1520 For TeleMetrum altimeters, you can locate the rocket in the
1521 sky using the elevation and bearing information to figure
1522 out where to look. Elevation is in degrees above the
1523 horizon. Bearing is reported in degrees relative to true
1524 north. Range can help figure out how big the rocket will
1525 appear. Ground Distance shows how far it is to a point
1526 directly under the rocket and can help figure out where the
1527 rocket is likely to land. Note that all of these values are
1528 relative to the pad location. If the elevation is near 90°,
1529 the rocket is over the pad, not over you.
1532 Finally, the igniter voltages are reported in this tab as
1533 well, both to monitor the main charge as well as to see what
1534 the status of the apogee charge is. Note that some commercial
1535 e-matches are designed to retain continuity even after being
1536 fired, and will continue to show as green or return from red to
1541 <title>Landed</title>
1543 Once the rocket is on the ground, attention switches to
1544 recovery. While the radio signal is often lost once the
1545 rocket is on the ground, the last reported GPS position is
1546 generally within a short distance of the actual landing location.
1549 The last reported GPS position is reported both by
1550 latitude and longitude as well as a bearing and distance from
1551 the launch pad. The distance should give you a good idea of
1552 whether to walk or hitch a ride. Take the reported
1553 latitude and longitude and enter them into your hand-held GPS
1554 unit and have that compute a track to the landing location.
1557 Both TeleMini and TeleMetrum will continue to transmit RDF
1558 tones after landing, allowing you to locate the rocket by
1559 following the radio signal if necessary. You may need to get
1560 away from the clutter of the flight line, or even get up on
1561 a hill (or your neighbor's RV roof) to receive the RDF signal.
1564 The maximum height, speed and acceleration reported
1565 during the flight are displayed for your admiring observers.
1566 The accuracy of these immediate values depends on the quality
1567 of your radio link and how many packets were received.
1568 Recovering the on-board data after flight will likely yield
1569 more precise results.
1572 To get more detailed information about the flight, you can
1573 click on the 'Graph Flight' button which will bring up a
1574 graph window for the current flight.
1578 <title>Site Map</title>
1580 When the TeleMetrum has a GPS fix, the Site Map tab will map
1581 the rocket's position to make it easier for you to locate the
1582 rocket, both while it is in the air, and when it has landed. The
1583 rocket's state is indicated by color: white for pad, red for
1584 boost, pink for fast, yellow for coast, light blue for drogue,
1585 dark blue for main, and black for landed.
1588 The map's scale is approximately 3m (10ft) per pixel. The map
1589 can be dragged using the left mouse button. The map will attempt
1590 to keep the rocket roughly centered while data is being received.
1593 Images are fetched automatically via the Google Maps Static API,
1594 and cached on disk for reuse. If map images cannot be downloaded,
1595 the rocket's path will be traced on a dark gray background
1599 You can pre-load images for your favorite launch sites
1600 before you leave home; check out the 'Preload Maps' section below.
1605 <title>Save Flight Data</title>
1607 The altimeter records flight data to its internal flash memory.
1608 TeleMetrum data is recorded at a much higher rate than the telemetry
1609 system can handle, and is not subject to radio drop-outs. As
1610 such, it provides a more complete and precise record of the
1611 flight. The 'Save Flight Data' button allows you to read the
1612 flash memory and write it to disk. As TeleMini has only a barometer, it
1613 records data at the same rate as the telemetry signal, but there will be
1614 no data lost due to telemetry drop-outs.
1617 Clicking on the 'Save Flight Data' button brings up a list of
1618 connected TeleMetrum and TeleDongle devices. If you select a
1619 TeleMetrum device, the flight data will be downloaded from that
1620 device directly. If you select a TeleDongle device, flight data
1621 will be downloaded from an altimeter over radio link via the
1622 specified TeleDongle. See the chapter on Controlling An Altimeter
1623 Over The Radio Link for more information.
1626 After the device has been selected, a dialog showing the
1627 flight data saved in the device will be shown allowing you to
1628 select which flights to download and which to delete. With
1629 version 0.9 or newer firmware, you must erase flights in order
1630 for the space they consume to be reused by another
1631 flight. This prevents accidentally losing flight data
1632 if you neglect to download data before flying again. Note that
1633 if there is no more space available in the device, then no
1634 data will be recorded during the next flight.
1637 The file name for each flight log is computed automatically
1638 from the recorded flight date, altimeter serial number and
1639 flight number information.
1643 <title>Replay Flight</title>
1645 Select this button and you are prompted to select a flight
1646 record file, either a .telem file recording telemetry data or a
1647 .eeprom file containing flight data saved from the altimeter
1651 Once a flight record is selected, the flight monitor interface
1652 is displayed and the flight is re-enacted in real time. Check
1653 the Monitor Flight chapter above to learn how this window operates.
1657 <title>Graph Data</title>
1659 Select this button and you are prompted to select a flight
1660 record file, either a .telem file recording telemetry data or a
1661 .eeprom file containing flight data saved from
1665 Once a flight record is selected, a window with four tabs is
1666 opened. The first tab contains a graph with acceleration
1667 (blue), velocity (green) and altitude (red) of the flight,
1668 measured in metric units. The apogee(yellow) and main(magenta)
1669 igniter voltages are also displayed; high voltages indicate
1670 continuity, low voltages indicate open circuits. The second
1671 tab lets you configure which data to show in the graph. The
1672 third contains some basic flight statistics while the fourth
1673 has a map with the ground track of the flight displayed.
1676 The graph can be zoomed into a particular area by clicking and
1677 dragging down and to the right. Once zoomed, the graph can be
1678 reset by clicking and dragging up and to the left. Holding down
1679 control and clicking and dragging allows the graph to be panned.
1680 The right mouse button causes a pop-up menu to be displayed, giving
1681 you the option save or print the plot.
1684 Note that telemetry files will generally produce poor graphs
1685 due to the lower sampling rate and missed telemetry packets.
1686 Use saved flight data in .eeprom files for graphing where possible.
1690 <title>Export Data</title>
1692 This tool takes the raw data files and makes them available for
1693 external analysis. When you select this button, you are prompted to
1695 data file (either .eeprom or .telem will do, remember that
1696 .eeprom files contain higher resolution and more continuous
1697 data). Next, a second dialog appears which is used to select
1698 where to write the resulting file. It has a selector to choose
1699 between CSV and KML file formats.
1702 <title>Comma Separated Value Format</title>
1704 This is a text file containing the data in a form suitable for
1705 import into a spreadsheet or other external data analysis
1706 tool. The first few lines of the file contain the version and
1707 configuration information from the altimeter, then
1708 there is a single header line which labels all of the
1709 fields. All of these lines start with a '#' character which
1710 many tools can be configured to skip over.
1713 The remaining lines of the file contain the data, with each
1714 field separated by a comma and at least one space. All of
1715 the sensor values are converted to standard units, with the
1716 barometric data reported in both pressure, altitude and
1717 height above pad units.
1721 <title>Keyhole Markup Language (for Google Earth)</title>
1723 This is the format used by Google Earth to provide an overlay
1724 within that application. With this, you can use Google Earth to
1725 see the whole flight path in 3D.
1730 <title>Configure Altimeter</title>
1732 Select this button and then select either an altimeter or
1733 TeleDongle Device from the list provided. Selecting a TeleDongle
1734 device will use the radio link to configure a remote altimeter.
1737 The first few lines of the dialog provide information about the
1738 connected device, including the product name,
1739 software version and hardware serial number. Below that are the
1740 individual configuration entries.
1743 At the bottom of the dialog, there are four buttons:
1748 Save. This writes any changes to the
1749 configuration parameter block in flash memory. If you don't
1750 press this button, any changes you make will be lost.
1755 Reset. This resets the dialog to the most recently saved values,
1756 erasing any changes you have made.
1761 Reboot. This reboots the device. Use this to
1762 switch from idle to pad mode by rebooting once the rocket is
1763 oriented for flight, or to confirm changes you think you saved
1769 Close. This closes the dialog. Any unsaved changes will be
1775 The rest of the dialog contains the parameters to be configured.
1778 <title>Main Deploy Altitude</title>
1780 This sets the altitude (above the recorded pad altitude) at
1781 which the 'main' igniter will fire. The drop-down menu shows
1782 some common values, but you can edit the text directly and
1783 choose whatever you like. If the apogee charge fires below
1784 this altitude, then the main charge will fire two seconds
1785 after the apogee charge fires.
1789 <title>Apogee Delay</title>
1791 When flying redundant electronics, it's often important to
1792 ensure that multiple apogee charges don't fire at precisely
1793 the same time, as that can over pressurize the apogee deployment
1794 bay and cause a structural failure of the air-frame. The Apogee
1795 Delay parameter tells the flight computer to fire the apogee
1796 charge a certain number of seconds after apogee has been
1801 <title>Radio Frequency</title>
1803 This configures which of the frequencies to use for both
1804 telemetry and packet command mode. Note that if you set this
1805 value via packet command mode, the TeleDongle frequency will
1806 also be automatically reconfigured to match so that
1807 communication will continue afterwards.
1811 <title>RF Calibration</title>
1813 The radios in every Altus Metrum device are calibrated at the
1814 factory to ensure that they transmit and receive on the
1815 specified frequency. If you need to you can adjust the calibration
1816 by changing this value. Do not do this without understanding what
1817 the value means, read the appendix on calibration and/or the source
1818 code for more information. To change a TeleDongle's calibration,
1819 you must reprogram the unit completely.
1823 <title>Telemetry/RDF/APRS Enable</title>
1825 Enables the radio for transmission during flight. When
1826 disabled, the radio will not transmit anything during flight
1831 <title>APRS Interval</title>
1833 How often to transmit GPS information via APRS. This option
1834 is available on TeleMetrum v2 and TeleMega
1835 boards. TeleMetrum v1 boards cannot transmit APRS
1836 packets. Note that a single APRS packet takes nearly a full
1837 second to transmit, so enabling this option will prevent
1838 sending any other telemetry during that time.
1842 <title>Callsign</title>
1844 This sets the call sign included in each telemetry packet. Set this
1845 as needed to conform to your local radio regulations.
1849 <title>Maximum Flight Log Size</title>
1851 This sets the space (in kilobytes) allocated for each flight
1852 log. The available space will be divided into chunks of this
1853 size. A smaller value will allow more flights to be stored,
1854 a larger value will record data from longer flights.
1858 <title>Ignite Mode</title>
1860 TeleMetrum and TeleMini provide two igniter channels as they
1861 were originally designed as dual-deploy flight
1862 computers. This configuration parameter allows the two
1863 channels to be used in different configurations.
1868 Dual Deploy. This is the usual mode of operation; the
1869 'apogee' channel is fired at apogee and the 'main'
1870 channel at the height above ground specified by the
1871 'Main Deploy Altitude' during descent.
1876 Redundant Apogee. This fires both channels at
1877 apogee, the 'apogee' channel first followed after a two second
1878 delay by the 'main' channel.
1883 Redundant Main. This fires both channels at the
1884 height above ground specified by the Main Deploy
1885 Altitude setting during descent. The 'apogee'
1886 channel is fired first, followed after a two second
1887 delay by the 'main' channel.
1893 <title>Pad Orientation</title>
1895 Because it includes an accelerometer, TeleMetrum and
1896 TeleMega are sensitive to the orientation of the board. By
1897 default, it expects the antenna end to point forward. This
1898 parameter allows that default to be changed, permitting the
1899 board to be mounted with the antenna pointing aft instead.
1904 Antenna Up. In this mode, the antenna end of the
1905 TeleMetrum board must point forward, in line with the
1906 expected flight path.
1911 Antenna Down. In this mode, the antenna end of the
1912 TeleMetrum board must point aft, in line with the
1913 expected flight path.
1919 <title>Configure Pyro Channels</title>
1921 This opens a separate window to configure the additional
1922 pyro channels available on TeleMega. One column is presented
1923 for each channel. Each row represents a single parameter, if
1924 enabled the parameter must meet the specified test for the
1925 pyro channel to be fired.
1937 <title>Configure AltosUI</title>
1939 This button presents a dialog so that you can configure the AltosUI global settings.
1942 <title>Voice Settings</title>
1944 AltosUI provides voice announcements during flight so that you
1945 can keep your eyes on the sky and still get information about
1946 the current flight status. However, sometimes you don't want
1951 <para>Enable—turns all voice announcements on and off</para>
1955 Test Voice—Plays a short message allowing you to verify
1956 that the audio system is working and the volume settings
1963 <title>Log Directory</title>
1965 AltosUI logs all telemetry data and saves all TeleMetrum flash
1966 data to this directory. This directory is also used as the
1967 staring point when selecting data files for display or export.
1970 Click on the directory name to bring up a directory choosing
1971 dialog, select a new directory and click 'Select Directory' to
1972 change where AltosUI reads and writes data files.
1976 <title>Callsign</title>
1978 This value is transmitted in each command packet sent from
1979 TeleDongle and received from an altimeter. It is not used in
1980 telemetry mode, as the callsign configured in the altimeter board
1981 is included in all telemetry packets. Configure this
1982 with the AltosUI operators call sign as needed to comply with
1983 your local radio regulations.
1986 Note that to successfully command a flight computer over the radio
1987 (to configure the altimeter, monitor idle, or fire pyro charges),
1988 the callsign configured here must exactly match the callsign
1989 configured in the flight computer. This matching is case
1994 <title>Imperial Units</title>
1996 This switches between metric units (meters) and imperial
1997 units (feet and miles). This affects the display of values
1998 use during flight monitoring, data graphing and all of the
1999 voice announcements. It does not change the units used when
2000 exporting to CSV files, those are always produced in metric units.
2004 <title>Font Size</title>
2006 Selects the set of fonts used in the flight monitor
2007 window. Choose between the small, medium and large sets.
2011 <title>Serial Debug</title>
2013 This causes all communication with a connected device to be
2014 dumped to the console from which AltosUI was started. If
2015 you've started it from an icon or menu entry, the output
2016 will simply be discarded. This mode can be useful to debug
2017 various serial communication issues.
2021 <title>Manage Frequencies</title>
2023 This brings up a dialog where you can configure the set of
2024 frequencies shown in the various frequency menus. You can
2025 add as many as you like, or even reconfigure the default
2026 set. Changing this list does not affect the frequency
2027 settings of any devices, it only changes the set of
2028 frequencies shown in the menus.
2033 <title>Configure Groundstation</title>
2035 Select this button and then select a TeleDongle Device from the list provided.
2038 The first few lines of the dialog provide information about the
2039 connected device, including the product name,
2040 software version and hardware serial number. Below that are the
2041 individual configuration entries.
2044 Note that the TeleDongle itself doesn't save any configuration
2045 data, the settings here are recorded on the local machine in
2046 the Java preferences database. Moving the TeleDongle to
2047 another machine, or using a different user account on the same
2048 machine will cause settings made here to have no effect.
2051 At the bottom of the dialog, there are three buttons:
2056 Save. This writes any changes to the
2057 local Java preferences file. If you don't
2058 press this button, any changes you make will be lost.
2063 Reset. This resets the dialog to the most recently saved values,
2064 erasing any changes you have made.
2069 Close. This closes the dialog. Any unsaved changes will be
2075 The rest of the dialog contains the parameters to be configured.
2078 <title>Frequency</title>
2080 This configures the frequency to use for both telemetry and
2081 packet command mode. Set this before starting any operation
2082 involving packet command mode so that it will use the right
2083 frequency. Telemetry monitoring mode also provides a menu to
2084 change the frequency, and that menu also sets the same Java
2085 preference value used here.
2089 <title>Radio Calibration</title>
2091 The radios in every Altus Metrum device are calibrated at the
2092 factory to ensure that they transmit and receive on the
2093 specified frequency. To change a TeleDongle's calibration,
2094 you must reprogram the unit completely, so this entry simply
2095 shows the current value and doesn't allow any changes.
2100 <title>Flash Image</title>
2102 This reprograms any Altus Metrum device by using a TeleMetrum
2103 or TeleDongle as a programming dongle. Please read the
2104 directions for flashing devices in the Updating Device
2105 Firmware chapter below.
2108 Once you have the programmer and target devices connected,
2109 push the 'Flash Image' button. That will present a dialog box
2110 listing all of the connected devices. Carefully select the
2111 programmer device, not the device to be programmed.
2114 Next, select the image to flash to the device. These are named
2115 with the product name and firmware version. The file selector
2116 will start in the directory containing the firmware included
2117 with the AltosUI package. Navigate to the directory containing
2118 the desired firmware if it isn't there.
2121 Next, a small dialog containing the device serial number and
2122 RF calibration values should appear. If these values are
2123 incorrect (possibly due to a corrupted image in the device),
2124 enter the correct values here.
2127 Finally, a dialog containing a progress bar will follow the
2128 programming process.
2131 When programming is complete, the target device will
2132 reboot. Note that if the target device is connected via USB, you
2133 will have to unplug it and then plug it back in for the USB
2134 connection to reset so that you can communicate with the device
2139 <title>Fire Igniter</title>
2141 This activates the igniter circuits in TeleMetrum to help test
2142 recovery systems deployment. Because this command can operate
2143 over the Packet Command Link, you can prepare the rocket as
2144 for flight and then test the recovery system without needing
2145 to snake wires inside the air-frame.
2148 Selecting the 'Fire Igniter' button brings up the usual device
2149 selection dialog. Pick the desired TeleDongle or TeleMetrum
2150 device. This brings up another window which shows the current
2151 continuity test status for both apogee and main charges.
2154 Next, select the desired igniter to fire. This will enable the
2158 Select the 'Arm' button. This enables the 'Fire' button. The
2159 word 'Arm' is replaced by a countdown timer indicating that
2160 you have 10 seconds to press the 'Fire' button or the system
2161 will deactivate, at which point you start over again at
2162 selecting the desired igniter.
2166 <title>Scan Channels</title>
2168 This listens for telemetry packets on all of the configured
2169 frequencies, displaying information about each device it
2170 receives a packet from. You can select which of the three
2171 telemetry formats should be tried; by default, it only listens
2172 for the standard telemetry packets used in v1.0 and later
2177 <title>Load Maps</title>
2179 Before heading out to a new launch site, you can use this to
2180 load satellite images in case you don't have internet
2181 connectivity at the site. This loads a fairly large area
2182 around the launch site, which should cover any flight you're likely to make.
2185 There's a drop-down menu of launch sites we know about; if
2186 your favorites aren't there, please let us know the lat/lon
2187 and name of the site. The contents of this list are actually
2188 downloaded at run-time, so as new sites are sent in, they'll
2189 get automatically added to this list.
2192 If the launch site isn't in the list, you can manually enter the lat/lon values
2195 Clicking the 'Load Map' button will fetch images from Google
2196 Maps; note that Google limits how many images you can fetch at
2197 once, so if you load more than one launch site, you may get
2198 some gray areas in the map which indicate that Google is tired
2199 of sending data to you. Try again later.
2203 <title>Monitor Idle</title>
2205 This brings up a dialog similar to the Monitor Flight UI,
2206 except it works with the altimeter in “idle” mode by sending
2207 query commands to discover the current state rather than
2208 listening for telemetry packets.
2213 <title>AltosDroid</title>
2215 AltosDroid provides the same flight monitoring capabilities as
2216 AltosUI, but runs on Android devices and is designed to connect
2217 to a TeleBT receiver over Bluetooth™. Altos Droid monitors
2218 telemetry data, logging it to internal storage in the Android
2219 device, and presents that data in a UI the same way the 'Monitor
2220 Flight' window does in AltosUI.
2223 This manual will explain how to configure AltosDroid, connect
2224 to TeleBT, operate the flight monitoring interface and describe
2225 what the displayed data means.
2228 <title>Installing AltosDroid</title>
2230 AltosDroid is included in the Google Play store. To install
2231 it on your Android device, open open the Google Play Store
2232 application and search for “altosdroid”. Make sure you don't
2233 have a space between “altos” and “droid” or you probably won't
2234 find what you want. That should bring you to the right page
2235 from which you can download and install the application.
2239 <title>Connecting to TeleBT</title>
2241 Press the Android 'Menu' button or soft-key to see the
2242 configuration options available. Select the 'Connect a device'
2243 option and then the 'Scan for devices' entry at the bottom to
2244 look for your TeleBT device. Select your device, and when it
2245 asks for the code, enter '1234'.
2248 Subsequent connections will not require you to enter that
2249 code, and your 'paired' device will appear in the list without
2254 <title>Configuring AltosDroid</title>
2256 The only configuration option available for AltosDroid is
2257 which frequency to listen on. Press the Android 'Menu' button
2258 or soft-key and pick the 'Select radio frequency' entry. That
2259 brings up a menu of pre-set radio frequencies; pick the one
2260 which matches your altimeter.
2264 <title>Altos Droid Flight Monitoring</title>
2266 Altos Droid is designed to mimic the AltosUI flight monitoring
2267 display, providing separate tabs for each stage of your rocket
2268 flight along with a tab containing a map of the local area
2269 with icons marking the current location of the altimeter and
2275 The 'Launch Pad' tab shows information used to decide when the
2276 rocket is ready for flight. The first elements include red/green
2277 indicators, if any of these is red, you'll want to evaluate
2278 whether the rocket is ready to launch:
2282 Battery Voltage. This indicates whether the Li-Po battery
2283 powering the TeleMetrum has sufficient charge to last for
2284 the duration of the flight. A value of more than
2285 3.7V is required for a 'GO' status.
2290 Apogee Igniter Voltage. This indicates whether the apogee
2291 igniter has continuity. If the igniter has a low
2292 resistance, then the voltage measured here will be close
2293 to the Li-Po battery voltage. A value greater than 3.2V is
2294 required for a 'GO' status.
2299 Main Igniter Voltage. This indicates whether the main
2300 igniter has continuity. If the igniter has a low
2301 resistance, then the voltage measured here will be close
2302 to the Li-Po battery voltage. A value greater than 3.2V is
2303 required for a 'GO' status.
2308 On-board Data Logging. This indicates whether there is
2309 space remaining on-board to store flight data for the
2310 upcoming flight. If you've downloaded data, but failed
2311 to erase flights, there may not be any space
2312 left. TeleMetrum can store multiple flights, depending
2313 on the configured maximum flight log size. TeleMini
2314 stores only a single flight, so it will need to be
2315 downloaded and erased after each flight to capture
2316 data. This only affects on-board flight logging; the
2317 altimeter will still transmit telemetry and fire
2318 ejection charges at the proper times.
2323 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
2324 currently able to compute position information. GPS requires
2325 at least 4 satellites to compute an accurate position.
2330 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
2331 10 consecutive positions without losing lock. This ensures
2332 that the GPS receiver has reliable reception from the
2339 The Launchpad tab also shows the computed launch pad position
2340 and altitude, averaging many reported positions to improve the
2341 accuracy of the fix.
2346 <title>Downloading Flight Logs</title>
2348 Altos Droid always saves every bit of telemetry data it
2349 receives. To download that to a computer for use with AltosUI,
2350 simply remove the SD card from your Android device, or connect
2351 your device to your computer's USB port and browse the files
2352 on that device. You will find '.telem' files in the TeleMetrum
2353 directory that will work with AltosUI directly.
2358 <title>Using Altus Metrum Products</title>
2360 <title>Being Legal</title>
2362 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
2363 other authorization to legally operate the radio transmitters that are part
2368 <title>In the Rocket</title>
2370 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
2371 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
2372 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
2373 850mAh battery weighs less than a 9V alkaline battery, and will
2374 run a TeleMetrum for hours.
2375 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
2376 a few hours, or a TeleMini for much (much) longer.
2379 By default, we ship the altimeters with a simple wire antenna. If your
2380 electronics bay or the air-frame it resides within is made of carbon fiber,
2381 which is opaque to RF signals, you may choose to have an SMA connector
2382 installed so that you can run a coaxial cable to an antenna mounted
2383 elsewhere in the rocket.
2387 <title>On the Ground</title>
2389 To receive the data stream from the rocket, you need an antenna and short
2390 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. If possible, use an SMA to BNC
2391 adapter instead of feedline between the antenna feedpoint and
2392 TeleDongle, as this will give you the best performance. The
2393 TeleDongle in turn plugs directly into the USB port on a notebook
2394 computer. Because TeleDongle looks like a simple serial port, your computer
2395 does not require special device drivers... just plug it in.
2398 The GUI tool, AltosUI, is written in Java and runs across
2399 Linux, Mac OS and Windows. There's also a suite of C tools
2400 for Linux which can perform most of the same tasks.
2403 After the flight, you can use the radio link to extract the more detailed data
2404 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
2405 TeleMetrum board directly. Pulling out the data without having to open up
2406 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
2407 battery, so you'll want one of those anyway... the same cable used by lots
2408 of digital cameras and other modern electronic stuff will work fine.
2411 If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
2412 receiver, so that you can put in a way-point for the last reported rocket
2413 position before touch-down. This makes looking for your rocket a lot like
2414 Geo-Caching... just go to the way-point and look around starting from there.
2417 You may also enjoy having a ham radio “HT” that covers the 70cm band... you
2418 can use that with your antenna to direction-find the rocket on the ground
2419 the same way you can use a Walston or Beeline tracker. This can be handy
2420 if the rocket is hiding in sage brush or a tree, or if the last GPS position
2421 doesn't get you close enough because the rocket dropped into a canyon, or
2422 the wind is blowing it across a dry lake bed, or something like that... Keith
2423 and Bdale both currently own and use the Yaesu VX-7R at launches.
2426 So, to recap, on the ground the hardware you'll need includes:
2427 <orderedlist inheritnum='inherit' numeration='arabic'>
2430 an antenna and feed-line or adapter
2445 optionally, a hand-held GPS receiver
2450 optionally, an HT or receiver covering 435 MHz
2456 The best hand-held commercial directional antennas we've found for radio
2457 direction finding rockets are from
2458 <ulink url="http://www.arrowantennas.com/" >
2461 The 440-3 and 440-5 are both good choices for finding a
2462 TeleMetrum- or TeleMini- equipped rocket when used with a suitable
2463 70cm HT. TeleDongle and an SMA to BNC adapter fit perfectly
2464 between the driven element and reflector of Arrow antennas.
2468 <title>Data Analysis</title>
2470 Our software makes it easy to log the data from each flight, both the
2471 telemetry received during the flight itself, and the more
2472 complete data log recorded in the flash memory on the altimeter
2473 board. Once this data is on your computer, our post-flight tools make it
2474 easy to quickly get to the numbers everyone wants, like apogee altitude,
2475 max acceleration, and max velocity. You can also generate and view a
2476 standard set of plots showing the altitude, acceleration, and
2477 velocity of the rocket during flight. And you can even export a TeleMetrum data file
2478 usable with Google Maps and Google Earth for visualizing the flight path
2479 in two or three dimensions!
2482 Our ultimate goal is to emit a set of files for each flight that can be
2483 published as a web page per flight, or just viewed on your local disk with
2488 <title>Future Plans</title>
2490 In the future, we intend to offer “companion boards” for the rocket
2491 that will plug in to TeleMetrum to collect additional data, provide
2492 more pyro channels, and so forth.
2495 Also under design is a new flight computer with more sensors, more
2496 pyro channels, and a more powerful radio system designed for use
2497 in multi-stage, complex, and extreme altitude projects.
2500 We are also working on alternatives to TeleDongle. One is a
2501 a stand-alone, hand-held ground terminal that will allow monitoring
2502 the rocket's status, collecting data during flight, and logging data
2503 after flight without the need for a notebook computer on the
2504 flight line. Particularly since it is so difficult to read most
2505 notebook screens in direct sunlight, we think this will be a great
2506 thing to have. We are also working on a TeleDongle variant with
2507 Bluetooth that will work with Android phones and tablets.
2510 Because all of our work is open, both the hardware designs and the
2511 software, if you have some great idea for an addition to the current
2512 Altus Metrum family, feel free to dive in and help! Or let us know
2513 what you'd like to see that we aren't already working on, and maybe
2514 we'll get excited about it too...
2518 <ulink url="http://altusmetrum.org/">web site</ulink> for more news
2519 and information as our family of products evolves!
2524 <title>Altimeter Installation Recommendations</title>
2526 Building high-power rockets that fly safely is hard enough. Mix
2527 in some sophisticated electronics and a bunch of radio energy
2528 and oftentimes you find few perfect solutions. This chapter
2529 contains some suggestions about how to install Altus Metrum
2530 products into the rocket air-frame, including how to safely and
2531 reliably mix a variety of electronics into the same air-frame.
2534 <title>Mounting the Altimeter</title>
2536 The first consideration is to ensure that the altimeter is
2537 securely fastened to the air-frame. For TeleMetrum, we use
2538 nylon standoffs and nylon screws; they're good to at least 50G
2539 and cannot cause any electrical issues on the board. For
2540 TeleMini, we usually cut small pieces of 1/16 inch balsa to fit
2541 under the screw holes, and then take 2x56 nylon screws and
2542 screw them through the TeleMini mounting holes, through the
2543 balsa and into the underlying material.
2545 <orderedlist inheritnum='inherit' numeration='arabic'>
2548 Make sure TeleMetrum is aligned precisely along the axis of
2549 acceleration so that the accelerometer can accurately
2550 capture data during the flight.
2555 Watch for any metal touching components on the
2556 board. Shorting out connections on the bottom of the board
2557 can cause the altimeter to fail during flight.
2563 <title>Dealing with the Antenna</title>
2565 The antenna supplied is just a piece of solid, insulated,
2566 wire. If it gets damaged or broken, it can be easily
2567 replaced. It should be kept straight and not cut; bending or
2568 cutting it will change the resonant frequency and/or
2569 impedance, making it a less efficient radiator and thus
2570 reducing the range of the telemetry signal.
2573 Keeping metal away from the antenna will provide better range
2574 and a more even radiation pattern. In most rockets, it's not
2575 entirely possible to isolate the antenna from metal
2576 components; there are often bolts, all-thread and wires from other
2577 electronics to contend with. Just be aware that the more stuff
2578 like this around the antenna, the lower the range.
2581 Make sure the antenna is not inside a tube made or covered
2582 with conducting material. Carbon fiber is the most common
2583 culprit here -- CF is a good conductor and will effectively
2584 shield the antenna, dramatically reducing signal strength and
2585 range. Metallic flake paint is another effective shielding
2586 material which is to be avoided around any antennas.
2589 If the ebay is large enough, it can be convenient to simply
2590 mount the altimeter at one end and stretch the antenna out
2591 inside. Taping the antenna to the sled can keep it straight
2592 under acceleration. If there are metal rods, keep the
2593 antenna as far away as possible.
2596 For a shorter ebay, it's quite practical to have the antenna
2597 run through a bulkhead and into an adjacent bay. Drill a small
2598 hole in the bulkhead, pass the antenna wire through it and
2599 then seal it up with glue or clay. We've also used acrylic
2600 tubing to create a cavity for the antenna wire. This works a
2601 bit better in that the antenna is known to stay straight and
2602 not get folded by recovery components in the bay. Angle the
2603 tubing towards the side wall of the rocket and it ends up
2604 consuming very little space.
2607 If you need to place the antenna at a distance from the
2608 altimeter, you can replace the antenna with an edge-mounted
2609 SMA connector, and then run 50Ω coax from the board to the
2610 antenna. Building a remote antenna is beyond the scope of this
2615 <title>Preserving GPS Reception</title>
2617 The GPS antenna and receiver in TeleMetrum are highly
2618 sensitive and normally have no trouble tracking enough
2619 satellites to provide accurate position information for
2620 recovering the rocket. However, there are many ways to
2621 attenuate the GPS signal.
2622 <orderedlist inheritnum='inherit' numeration='arabic'>
2625 Conductive tubing or coatings. Carbon fiber and metal
2626 tubing, or metallic paint will all dramatically attenuate the
2627 GPS signal. We've never heard of anyone successfully
2628 receiving GPS from inside these materials.
2633 Metal components near the GPS patch antenna. These will
2634 de-tune the patch antenna, changing the resonant frequency
2635 away from the L1 carrier and reduce the effectiveness of the
2636 antenna. You can place as much stuff as you like beneath the
2637 antenna as that's covered with a ground plane. But, keep
2638 wires and metal out from above the patch antenna.
2645 <title>Radio Frequency Interference</title>
2647 Any altimeter will generate RFI; the digital circuits use
2648 high-frequency clocks that spray radio interference across a
2649 wide band. Altus Metrum altimeters generate intentional radio
2650 signals as well, increasing the amount of RF energy around the board.
2653 Rocketry altimeters also use precise sensors measuring air
2654 pressure and acceleration. Tiny changes in voltage can cause
2655 these sensor readings to vary by a huge amount. When the
2656 sensors start mis-reporting data, the altimeter can either
2657 fire the igniters at the wrong time, or not fire them at all.
2660 Voltages are induced when radio frequency energy is
2661 transmitted from one circuit to another. Here are things that
2662 influence the induced voltage and current:
2667 Keep wires from different circuits apart. Moving circuits
2668 further apart will reduce RFI.
2673 Avoid parallel wires from different circuits. The longer two
2674 wires run parallel to one another, the larger the amount of
2675 transferred energy. Cross wires at right angles to reduce
2681 Twist wires from the same circuits. Two wires the same
2682 distance from the transmitter will get the same amount of
2683 induced energy which will then cancel out. Any time you have
2684 a wire pair running together, twist the pair together to
2685 even out distances and reduce RFI. For altimeters, this
2686 includes battery leads, switch hookups and igniter
2692 Avoid resonant lengths. Know what frequencies are present
2693 in the environment and avoid having wire lengths near a
2694 natural resonant length. Altusmetrum products transmit on the
2695 70cm amateur band, so you should avoid lengths that are a
2696 simple ratio of that length; essentially any multiple of ¼
2697 of the wavelength (17.5cm).
2703 <title>The Barometric Sensor</title>
2705 Altusmetrum altimeters measure altitude with a barometric
2706 sensor, essentially measuring the amount of air above the
2707 rocket to figure out how high it is. A large number of
2708 measurements are taken as the altimeter initializes itself to
2709 figure out the pad altitude. Subsequent measurements are then
2710 used to compute the height above the pad.
2713 To accurately measure atmospheric pressure, the ebay
2714 containing the altimeter must be vented outside the
2715 air-frame. The vent must be placed in a region of linear
2716 airflow, have smooth edges, and away from areas of increasing or
2717 decreasing pressure.
2720 The barometric sensor in the altimeter is quite sensitive to
2721 chemical damage from the products of APCP or BP combustion, so
2722 make sure the ebay is carefully sealed from any compartment
2723 which contains ejection charges or motors.
2727 <title>Ground Testing</title>
2729 The most important aspect of any installation is careful
2730 ground testing. Bringing an air-frame up to the LCO table which
2731 hasn't been ground tested can lead to delays or ejection
2732 charges firing on the pad, or, even worse, a recovery system
2736 Do a 'full systems' test that includes wiring up all igniters
2737 without any BP and turning on all of the electronics in flight
2738 mode. This will catch any mistakes in wiring and any residual
2739 RFI issues that might accidentally fire igniters at the wrong
2740 time. Let the air-frame sit for several minutes, checking for
2741 adequate telemetry signal strength and GPS lock. If any igniters
2742 fire unexpectedly, find and resolve the issue before loading any
2746 Ground test the ejection charges. Prepare the rocket for
2747 flight, loading ejection charges and igniters. Completely
2748 assemble the air-frame and then use the 'Fire Igniters'
2749 interface through a TeleDongle to command each charge to
2750 fire. Make sure the charge is sufficient to robustly separate
2751 the air-frame and deploy the recovery system.
2756 <title>Updating Device Firmware</title>
2758 The big concept to understand is that you have to use a
2759 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
2760 and a TeleMetrum or other TeleDongle to program the TeleDongle
2761 Due to limited memory resources in the cc1111, we don't support
2762 programming directly over USB.
2765 You may wish to begin by ensuring you have current firmware images.
2766 These are distributed as part of the AltOS software bundle that
2767 also includes the AltosUI ground station program. Newer ground
2768 station versions typically work fine with older firmware versions,
2769 so you don't need to update your devices just to try out new
2770 software features. You can always download the most recent
2771 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
2774 We recommend updating the altimeter first, before updating TeleDongle.
2777 <title>Updating TeleMetrum Firmware</title>
2778 <orderedlist inheritnum='inherit' numeration='arabic'>
2781 Find the 'programming cable' that you got as part of the starter
2782 kit, that has a red 8-pin MicroMaTch connector on one end and a
2783 red 4-pin MicroMaTch connector on the other end.
2788 Take the 2 screws out of the TeleDongle case to get access
2789 to the circuit board.
2794 Plug the 8-pin end of the programming cable to the
2795 matching connector on the TeleDongle, and the 4-pin end to the
2796 matching connector on the TeleMetrum.
2797 Note that each MicroMaTch connector has an alignment pin that
2798 goes through a hole in the PC board when you have the cable
2804 Attach a battery to the TeleMetrum board.
2809 Plug the TeleDongle into your computer's USB port, and power
2815 Run AltosUI, and select 'Flash Image' from the File menu.
2820 Pick the TeleDongle device from the list, identifying it as the
2826 Select the image you want put on the TeleMetrum, which should have a
2827 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
2828 in the default directory, if not you may have to poke around
2829 your system to find it.
2834 Make sure the configuration parameters are reasonable
2835 looking. If the serial number and/or RF configuration
2836 values aren't right, you'll need to change them.
2841 Hit the 'OK' button and the software should proceed to flash
2842 the TeleMetrum with new firmware, showing a progress bar.
2847 Confirm that the TeleMetrum board seems to have updated OK, which you
2848 can do by plugging in to it over USB and using a terminal program
2849 to connect to the board and issue the 'v' command to check
2855 If something goes wrong, give it another try.
2861 <title>Updating TeleMini Firmware</title>
2862 <orderedlist inheritnum='inherit' numeration='arabic'>
2865 You'll need a special 'programming cable' to reprogram the
2866 TeleMini. It's available on the Altus Metrum web store, or
2867 you can make your own using an 8-pin MicroMaTch connector on
2868 one end and a set of four pins on the other.
2873 Take the 2 screws out of the TeleDongle case to get access
2874 to the circuit board.
2879 Plug the 8-pin end of the programming cable to the matching
2880 connector on the TeleDongle, and the 4-pins into the holes
2881 in the TeleMini circuit board. Note that the MicroMaTch
2882 connector has an alignment pin that goes through a hole in
2883 the PC board when you have the cable oriented correctly, and
2884 that pin 1 on the TeleMini board is marked with a square pad
2885 while the other pins have round pads.
2890 Attach a battery to the TeleMini board.
2895 Plug the TeleDongle into your computer's USB port, and power
2901 Run AltosUI, and select 'Flash Image' from the File menu.
2906 Pick the TeleDongle device from the list, identifying it as the
2912 Select the image you want put on the TeleMini, which should have a
2913 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
2914 in the default directory, if not you may have to poke around
2915 your system to find it.
2920 Make sure the configuration parameters are reasonable
2921 looking. If the serial number and/or RF configuration
2922 values aren't right, you'll need to change them.
2927 Hit the 'OK' button and the software should proceed to flash
2928 the TeleMini with new firmware, showing a progress bar.
2933 Confirm that the TeleMini board seems to have updated OK, which you
2934 can do by configuring it over the radio link through the TeleDongle, or
2935 letting it come up in “flight” mode and listening for telemetry.
2940 If something goes wrong, give it another try.
2946 <title>Updating TeleDongle Firmware</title>
2948 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
2949 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
2951 <orderedlist inheritnum='inherit' numeration='arabic'>
2954 Find the 'programming cable' that you got as part of the starter
2955 kit, that has a red 8-pin MicroMaTch connector on one end and a
2956 red 4-pin MicroMaTch connector on the other end.
2961 Find the USB cable that you got as part of the starter kit, and
2962 plug the “mini” end in to the mating connector on TeleMetrum or TeleDongle.
2967 Take the 2 screws out of the TeleDongle case to get access
2968 to the circuit board.
2973 Plug the 8-pin end of the programming cable to the
2974 matching connector on the programmer, and the 4-pin end to the
2975 matching connector on the TeleDongle.
2976 Note that each MicroMaTch connector has an alignment pin that
2977 goes through a hole in the PC board when you have the cable
2983 Attach a battery to the TeleMetrum board if you're using one.
2988 Plug both the programmer and the TeleDongle into your computer's USB
2989 ports, and power up the programmer.
2994 Run AltosUI, and select 'Flash Image' from the File menu.
2999 Pick the programmer device from the list, identifying it as the
3005 Select the image you want put on the TeleDongle, which should have a
3006 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
3007 in the default directory, if not you may have to poke around
3008 your system to find it.
3013 Make sure the configuration parameters are reasonable
3014 looking. If the serial number and/or RF configuration
3015 values aren't right, you'll need to change them. The TeleDongle
3016 serial number is on the “bottom” of the circuit board, and can
3017 usually be read through the translucent blue plastic case without
3018 needing to remove the board from the case.
3023 Hit the 'OK' button and the software should proceed to flash
3024 the TeleDongle with new firmware, showing a progress bar.
3029 Confirm that the TeleDongle board seems to have updated OK, which you
3030 can do by plugging in to it over USB and using a terminal program
3031 to connect to the board and issue the 'v' command to check
3032 the version, etc. Once you're happy, remove the programming cable
3033 and put the cover back on the TeleDongle.
3038 If something goes wrong, give it another try.
3043 Be careful removing the programming cable from the locking 8-pin
3044 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
3045 screwdriver or knife blade to gently pry the locking ears out
3046 slightly to extract the connector. We used a locking connector on
3047 TeleMetrum to help ensure that the cabling to companion boards
3048 used in a rocket don't ever come loose accidentally in flight.
3053 <title>Hardware Specifications</title>
3055 <title>TeleMetrum Specifications</title>
3059 Recording altimeter for model rocketry.
3064 Supports dual deployment (can fire 2 ejection charges).
3069 70cm ham-band transceiver for telemetry down-link.
3074 Barometric pressure sensor good to 45k feet MSL.
3079 1-axis high-g accelerometer for motor characterization, capable of
3080 +/- 50g using default part.
3085 On-board, integrated GPS receiver with 5Hz update rate capability.
3090 On-board 1 megabyte non-volatile memory for flight data storage.
3095 USB interface for battery charging, configuration, and data recovery.
3100 Fully integrated support for Li-Po rechargeable batteries.
3105 Uses Li-Po to fire e-matches, can be modified to support
3106 optional separate pyro battery if needed.
3111 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
3117 <title>TeleMini Specifications</title>
3121 Recording altimeter for model rocketry.
3126 Supports dual deployment (can fire 2 ejection charges).
3131 70cm ham-band transceiver for telemetry down-link.
3136 Barometric pressure sensor good to 45k feet MSL.
3141 On-board 5 kilobyte non-volatile memory for flight data storage.
3146 RF interface for configuration, and data recovery.
3151 Support for Li-Po rechargeable batteries, using an external charger.
3156 Uses Li-Po to fire e-matches, can be modified to support
3157 optional separate pyro battery if needed.
3162 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
3171 TeleMetrum seems to shut off when disconnected from the
3172 computer. Make sure the battery is adequately charged. Remember the
3173 unit will pull more power than the USB port can deliver before the
3174 GPS enters “locked” mode. The battery charges best when TeleMetrum
3178 It's impossible to stop the TeleDongle when it's in “p” mode, I have
3179 to unplug the USB cable? Make sure you have tried to “escape out” of
3180 this mode. If this doesn't work the reboot procedure for the
3181 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
3182 outgoing buffer IF your “escape out” ('~~') does not work.
3183 At this point using either 'ao-view' (or possibly
3184 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
3188 The amber LED (on the TeleMetrum) lights up when both
3189 battery and USB are connected. Does this mean it's charging?
3190 Yes, the yellow LED indicates the charging at the 'regular' rate.
3191 If the led is out but the unit is still plugged into a USB port,
3192 then the battery is being charged at a 'trickle' rate.
3195 There are no “dit-dah-dah-dit” sound or lights like the manual mentions?
3196 That's the “pad” mode. Weak batteries might be the problem.
3197 It is also possible that the TeleMetrum is horizontal and the output
3198 is instead a “dit-dit” meaning 'idle'. For TeleMini, it's possible that
3199 it received a command packet which would have left it in “pad” mode.
3202 How do I save flight data?
3203 Live telemetry is written to file(s) whenever AltosUI is connected
3204 to the TeleDongle. The file area defaults to ~/TeleMetrum
3205 but is easily changed using the menus in AltosUI. The files that
3206 are written end in '.telem'. The after-flight
3207 data-dumped files will end in .eeprom and represent continuous data
3208 unlike the .telem files that are subject to losses
3209 along the RF data path.
3210 See the above instructions on what and how to save the eeprom stored
3211 data after physically retrieving your altimeter. Make sure to save
3212 the on-board data after each flight; while the TeleMetrum can store
3213 multiple flights, you never know when you'll lose the altimeter...
3217 <title>Notes for Older Software</title>
3220 Before AltosUI was written, using Altus Metrum devices required
3221 some finesse with the Linux command line. There was a limited
3222 GUI tool, ao-view, which provided functionality similar to the
3223 Monitor Flight window in AltosUI, but everything else was a
3224 fairly 80's experience. This appendix includes documentation for
3225 using that software.
3229 Both TeleMetrum and TeleDongle can be directly communicated
3230 with using USB ports. The first thing you should try after getting
3231 both units plugged into to your computer's USB port(s) is to run
3232 'ao-list' from a terminal-window to see what port-device-name each
3233 device has been assigned by the operating system.
3234 You will need this information to access the devices via their
3235 respective on-board firmware and data using other command line
3236 programs in the AltOS software suite.
3239 TeleMini can be communicated with through a TeleDongle device
3240 over the radio link. When first booted, TeleMini listens for a
3241 TeleDongle device and if it receives a packet, it goes into
3242 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
3243 launched. The easiest way to get it talking is to start the
3244 communication link on the TeleDongle and the power up the
3248 To access the device's firmware for configuration you need a terminal
3249 program such as you would use to talk to a modem. The software
3250 authors prefer using the program 'cu' which comes from the UUCP package
3251 on most Unix-like systems such as Linux. An example command line for
3252 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
3253 indicated from running the
3254 ao-list program. Another reasonable terminal program for Linux is
3255 'cutecom'. The default 'escape'
3256 character used by CU (i.e. the character you use to
3257 issue commands to cu itself instead of sending the command as input
3258 to the connected device) is a '~'. You will need this for use in
3259 only two different ways during normal operations. First is to exit
3260 the program by sending a '~.' which is called a 'escape-disconnect'
3261 and allows you to close-out from 'cu'. The
3262 second use will be outlined later.
3265 All of the Altus Metrum devices share the concept of a two level
3266 command set in their firmware.
3267 The first layer has several single letter commands. Once
3268 you are using 'cu' (or 'cutecom') sending (typing) a '?'
3269 returns a full list of these
3270 commands. The second level are configuration sub-commands accessed
3271 using the 'c' command, for
3272 instance typing 'c?' will give you this second level of commands
3273 (all of which require the
3274 letter 'c' to access). Please note that most configuration options
3275 are stored only in Flash memory; TeleDongle doesn't provide any storage
3276 for these options and so they'll all be lost when you unplug it.
3279 Try setting these configuration ('c' or second level menu) values. A good
3280 place to start is by setting your call sign. By default, the boards
3281 use 'N0CALL' which is cute, but not exactly legal!
3282 Spend a few minutes getting comfortable with the units, their
3283 firmware, and 'cu' (or possibly 'cutecom').
3284 For instance, try to send
3285 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
3286 Verify you can connect and disconnect from the units while in your
3287 terminal program by sending the escape-disconnect mentioned above.
3290 To set the radio frequency, use the 'c R' command to specify the
3291 radio transceiver configuration parameter. This parameter is computed
3292 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
3293 the standard calibration reference frequency, 'S', (normally 434.550MHz):
3297 Round the result to the nearest integer value.
3298 As with all 'c' sub-commands, follow this with a 'c w' to write the
3299 change to the parameter block in the on-board flash on
3300 your altimeter board if you want the change to stay in place across reboots.
3303 To set the apogee delay, use the 'c d' command.
3304 As with all 'c' sub-commands, follow this with a 'c w' to write the
3305 change to the parameter block in the on-board DataFlash chip.
3308 To set the main deployment altitude, use the 'c m' command.
3309 As with all 'c' sub-commands, follow this with a 'c w' to write the
3310 change to the parameter block in the on-board DataFlash chip.
3313 To calibrate the radio frequency, connect the UHF antenna port to a
3314 frequency counter, set the board to 434.550MHz, and use the 'C'
3315 command to generate a CW carrier. Wait for the transmitter temperature
3316 to stabilize and the frequency to settle down.
3317 Then, divide 434.550 MHz by the
3318 measured frequency and multiply by the current radio cal value show
3319 in the 'c s' command. For an unprogrammed board, the default value
3320 is 1186611. Take the resulting integer and program it using the 'c f'
3321 command. Testing with the 'C' command again should show a carrier
3322 within a few tens of Hertz of the intended frequency.
3323 As with all 'c' sub-commands, follow this with a 'c w' to write the
3324 change to the parameter block in the on-board DataFlash chip.
3327 Note that the 'reboot' command, which is very useful on the altimeters,
3328 will likely just cause problems with the dongle. The *correct* way
3329 to reset the dongle is just to unplug and re-plug it.
3332 A fun thing to do at the launch site and something you can do while
3333 learning how to use these units is to play with the radio link access
3334 between an altimeter and the TeleDongle. Be aware that you *must* create
3335 some physical separation between the devices, otherwise the link will
3336 not function due to signal overload in the receivers in each device.
3339 Now might be a good time to take a break and read the rest of this
3340 manual, particularly about the two “modes” that the altimeters
3341 can be placed in. TeleMetrum uses the position of the device when booting
3342 up will determine whether the unit is in “pad” or “idle” mode. TeleMini
3343 enters “idle” mode when it receives a command packet within the first 5 seconds
3344 of being powered up, otherwise it enters “pad” mode.
3347 You can access an altimeter in idle mode from the TeleDongle's USB
3348 connection using the radio link
3349 by issuing a 'p' command to the TeleDongle. Practice connecting and
3350 disconnecting ('~~' while using 'cu') from the altimeter. If
3351 you cannot escape out of the “p” command, (by using a '~~' when in
3352 CU) then it is likely that your kernel has issues. Try a newer version.
3355 Using this radio link allows you to configure the altimeter, test
3356 fire e-matches and igniters from the flight line, check pyro-match
3357 continuity and so forth. You can leave the unit turned on while it
3358 is in 'idle mode' and then place the
3359 rocket vertically on the launch pad, walk away and then issue a
3360 reboot command. The altimeter will reboot and start sending data
3361 having changed to the “pad” mode. If the TeleDongle is not receiving
3362 this data, you can disconnect 'cu' from the TeleDongle using the
3363 procedures mentioned above and THEN connect to the TeleDongle from
3364 inside 'ao-view'. If this doesn't work, disconnect from the
3365 TeleDongle, unplug it, and try again after plugging it back in.
3368 In order to reduce the chance of accidental firing of pyrotechnic
3369 charges, the command to fire a charge is intentionally somewhat
3370 difficult to type, and the built-in help is slightly cryptic to
3371 prevent accidental echoing of characters from the help text back at
3372 the board from firing a charge. The command to fire the apogee
3373 drogue charge is 'i DoIt drogue' and the command to fire the main
3374 charge is 'i DoIt main'.
3377 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
3378 and 'ao-view' will both auditorily announce and visually indicate
3380 Now you can launch knowing that you have a good data path and
3381 good satellite lock for flight data and recovery. Remember
3382 you MUST tell ao-view to connect to the TeleDongle explicitly in
3383 order for ao-view to be able to receive data.
3386 The altimeters provide RDF (radio direction finding) tones on
3387 the pad, during descent and after landing. These can be used to
3388 locate the rocket using a directional antenna; the signal
3389 strength providing an indication of the direction from receiver to rocket.
3392 TeleMetrum also provides GPS tracking data, which can further simplify
3393 locating the rocket once it has landed. (The last good GPS data
3394 received before touch-down will be on the data screen of 'ao-view'.)
3397 Once you have recovered the rocket you can download the eeprom
3398 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
3399 either a USB cable or over the radio link using TeleDongle.
3400 And by following the man page for 'ao-postflight' you can create
3401 various data output reports, graphs, and even KML data to see the
3402 flight trajectory in Google-earth. (Moving the viewing angle making
3403 sure to connect the yellow lines while in Google-earth is the proper
3407 As for ao-view.... some things are in the menu but don't do anything
3408 very useful. The developers have stopped working on ao-view to focus
3409 on a new, cross-platform ground station program. So ao-view may or
3410 may not be updated in the future. Mostly you just use
3411 the Log and Device menus. It has a wonderful display of the incoming
3412 flight data and I am sure you will enjoy what it has to say to you
3413 once you enable the voice output!
3417 <title>Drill Templates</title>
3419 These images, when printed, provide precise templates for the
3420 mounting holes in Altus Metrum flight computers
3423 <title>TeleMetrum template</title>
3425 TeleMetrum has overall dimensions of 1.000 x 2.750 inches, and the
3426 mounting holes are sized for use with 4-40 or M3 screws.
3428 <mediaobject id="TeleMetrumTemplate">
3430 <imagedata format="SVG" fileref="telemetrum.svg"/>
3435 <title>TeleMini template</title>
3437 TeleMini has overall dimensions of 0.500 x 1.500 inches, and the
3438 mounting holes are sized for use with 2-56 or M2 screws.
3440 <mediaobject id="TeleMiniTemplate">
3442 <imagedata format="SVG" fileref="telemini.svg"/>
3448 <title>Calibration</title>
3450 There are only two calibrations required for a TeleMetrum board, and
3451 only one for TeleDongle and TeleMini. All boards are shipped from
3452 the factory pre-calibrated, but the procedures are documented here
3453 in case they are ever needed. Re-calibration is not supported by
3454 AltosUI, you must connect to the board with a serial terminal program
3455 and interact directly with the on-board command interpreter to effect
3459 <title>Radio Frequency</title>
3461 The radio frequency is synthesized from a clock based on the 48 MHz
3462 crystal on the board. The actual frequency of this oscillator
3463 must be measured to generate a calibration constant. While our
3465 bandwidth is wide enough to allow boards to communicate even when
3466 their oscillators are not on exactly the same frequency, performance
3467 is best when they are closely matched.
3468 Radio frequency calibration requires a calibrated frequency counter.
3469 Fortunately, once set, the variation in frequency due to aging and
3470 temperature changes is small enough that re-calibration by customers
3471 should generally not be required.
3474 To calibrate the radio frequency, connect the UHF antenna port to a
3475 frequency counter, set the board to 434.550MHz, and use the 'C'
3476 command in the on-board command interpreter to generate a CW
3477 carrier. For TeleMetrum, this is best done over USB. For TeleMini,
3478 note that the only way to escape the 'C' command is via power cycle
3479 since the board will no longer be listening for commands once it
3480 starts generating a CW carrier.
3483 Wait for the transmitter temperature to stabilize and the frequency
3484 to settle down. Then, divide 434.550 MHz by the
3485 measured frequency and multiply by the current radio cal value show
3486 in the 'c s' command. For an unprogrammed board, the default value
3487 is 1186611. Take the resulting integer and program it using the 'c f'
3488 command. Testing with the 'C' command again should show a carrier
3489 within a few tens of Hertz of the intended frequency.
3490 As with all 'c' sub-commands, follow this with a 'c w' to write the
3491 change to the parameter block in the on-board DataFlash chip.
3494 Note that any time you re-do the radio frequency calibration, the
3495 radio frequency is reset to the default 434.550 Mhz. If you want
3496 to use another frequency, you will have to set that again after
3497 calibration is completed.
3501 <title>TeleMetrum Accelerometer</title>
3503 The TeleMetrum accelerometer we use has its own 5 volt power
3505 the output must be passed through a resistive voltage divider to match
3506 the input of our 3.3 volt ADC. This means that unlike the barometric
3507 sensor, the output of the acceleration sensor is not ratio-metric to
3508 the ADC converter, and calibration is required. Explicitly
3509 calibrating the accelerometers also allows us to load any device
3510 from a Freescale family that includes at least +/- 40g, 50g, 100g,
3511 and 200g parts. Using gravity,
3512 a simple 2-point calibration yields acceptable results capturing both
3513 the different sensitivities and ranges of the different accelerometer
3514 parts and any variation in power supply voltages or resistor values
3515 in the divider network.
3518 To calibrate the acceleration sensor, use the 'c a 0' command. You
3519 will be prompted to orient the board vertically with the UHF antenna
3520 up and press a key, then to orient the board vertically with the
3521 UHF antenna down and press a key. Note that the accuracy of this
3522 calibration depends primarily on how perfectly vertical and still
3523 the board is held during the cal process. As with all 'c'
3524 sub-commands, follow this with a 'c w' to write the
3525 change to the parameter block in the on-board DataFlash chip.
3528 The +1g and -1g calibration points are included in each telemetry
3529 frame and are part of the header stored in onboard flash to be
3530 downloaded after flight. We always store and return raw ADC
3531 samples for each sensor... so nothing is permanently “lost” or
3532 “damaged” if the calibration is poor.
3535 In the unlikely event an accel cal goes badly, it is possible
3536 that TeleMetrum may always come up in 'pad mode' and as such not be
3537 listening to either the USB or radio link. If that happens,
3538 there is a special hook in the firmware to force the board back
3539 in to 'idle mode' so you can re-do the cal. To use this hook, you
3540 just need to ground the SPI clock pin at power-on. This pin is
3541 available as pin 2 on the 8-pin companion connector, and pin 1 is
3542 ground. So either carefully install a fine-gauge wire jumper
3543 between the two pins closest to the index hole end of the 8-pin
3544 connector, or plug in the programming cable to the 8-pin connector
3545 and use a small screwdriver or similar to short the two pins closest
3546 to the index post on the 4-pin end of the programming cable, and
3547 power up the board. It should come up in 'idle mode' (two beeps),
3553 <title>Release Notes</title>
3555 <title>Version 1.3</title>
3557 xmlns:xi="http://www.w3.org/2001/XInclude"
3558 href="release-notes-1.3.xsl"
3559 xpointer="xpointer(/article/*)"/>
3562 <title>Version 1.2.1</title>
3564 xmlns:xi="http://www.w3.org/2001/XInclude"
3565 href="release-notes-1.2.1.xsl"
3566 xpointer="xpointer(/article/*)"/>
3569 <title>Version 1.2</title>
3571 xmlns:xi="http://www.w3.org/2001/XInclude"
3572 href="release-notes-1.2.xsl"
3573 xpointer="xpointer(/article/*)"/>
3576 <title>Version 1.1.1</title>
3578 xmlns:xi="http://www.w3.org/2001/XInclude"
3579 href="release-notes-1.1.1.xsl"
3580 xpointer="xpointer(/article/*)"/>
3583 <title>Version 1.1</title>
3585 xmlns:xi="http://www.w3.org/2001/XInclude"
3586 href="release-notes-1.1.xsl"
3587 xpointer="xpointer(/article/*)"/>
3590 <title>Version 1.0.1</title>
3592 xmlns:xi="http://www.w3.org/2001/XInclude"
3593 href="release-notes-1.0.1.xsl"
3594 xpointer="xpointer(/article/*)"/>
3597 <title>Version 0.9.2</title>
3599 xmlns:xi="http://www.w3.org/2001/XInclude"
3600 href="release-notes-0.9.2.xsl"
3601 xpointer="xpointer(/article/*)"/>
3604 <title>Version 0.9</title>
3606 xmlns:xi="http://www.w3.org/2001/XInclude"
3607 href="release-notes-0.9.xsl"
3608 xpointer="xpointer(/article/*)"/>
3611 <title>Version 0.8</title>
3613 xmlns:xi="http://www.w3.org/2001/XInclude"
3614 href="release-notes-0.8.xsl"
3615 xpointer="xpointer(/article/*)"/>
3618 <title>Version 0.7.1</title>
3620 xmlns:xi="http://www.w3.org/2001/XInclude"
3621 href="release-notes-0.7.1.xsl"
3622 xpointer="xpointer(/article/*)"/>
3627 <!-- LocalWords: Altusmetrum
projects / fw / altos / blob