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5 <title>The Altus Metrum System</title>
6 <subtitle>An Owner's Manual for TeleMetrum, TeleMini and TeleDongle Devices</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>1.0</revnumber>
40 <date>24 August 2011</date>
42 Updated for software version 1.0. Note that 1.0 represents a
43 telemetry format change, meaning both ends of a link
44 (TeleMetrum/TeleMini and TeleDongle) must be updated or
45 communications will fail.
49 <revnumber>0.9</revnumber>
50 <date>18 January 2011</date>
52 Updated for software version 0.9. Note that 0.9 represents a
53 telemetry format change, meaning both ends of a link (TeleMetrum and
54 TeleDongle) must be updated or communications will fail.
58 <revnumber>0.8</revnumber>
59 <date>24 November 2010</date>
60 <revremark>Updated for software version 0.8 </revremark>
66 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing "The
67 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
68 Kit" which formed the basis of the original Getting Started chapter
69 in this manual. Bob was one of our first customers for a production
70 TeleMetrum, and his continued enthusiasm and contributions
71 are immensely gratifying and highly appreciated!
74 And thanks to Anthony (AJ) Towns for major contributions including
75 the AltosUI graphing and site map code and associated documentation.
76 Free software means that our customers and friends can become our
77 collaborators, and we certainly appreciate this level of
81 Have fun using these products, and we hope to meet all of you
82 out on the rocket flight line somewhere.
85 NAR #87103, TRA #12201
88 NAR #88757, TRA #12200
93 <title>Introduction and Overview</title>
95 Welcome to the Altus Metrum community! Our circuits and software reflect
96 our passion for both hobby rocketry and Free Software. We hope their
97 capabilities and performance will delight you in every way, but by
98 releasing all of our hardware and software designs under open licenses,
99 we also hope to empower you to take as active a role in our collective
103 The first device created for our community was TeleMetrum, a dual
104 deploy altimeter with fully integrated GPS and radio telemetry
105 as standard features, and a "companion interface" that will
106 support optional capabilities in the future.
109 The newest device is TeleMini, a dual deploy altimeter with
110 radio telemetry and radio direction finding. This device is only
111 13mm by 38mm (½ inch by 1½ inches) and can fit easily in an 18mm
115 Complementing TeleMetrum and TeleMini is TeleDongle, a USB to RF
116 interface for communicating with the altimeters. Combined with your
117 choice of antenna and
118 notebook computer, TeleDongle and our associated user interface software
119 form a complete ground station capable of logging and displaying in-flight
120 telemetry, aiding rocket recovery, then processing and archiving flight
121 data for analysis and review.
124 More products will be added to the Altus Metrum family over time, and
125 we currently envision that this will be a single, comprehensive manual
126 for the entire product family.
130 <title>Getting Started</title>
132 The first thing to do after you check the inventory of parts in your
133 "starter kit" is to charge the battery.
136 The TeleMetrum battery can be charged by plugging it into the
137 corresponding socket of the TeleMetrum and then using the USB A to
139 cable to plug the TeleMetrum into your computer's USB socket. The
140 TeleMetrum circuitry will charge the battery whenever it is plugged
141 in, because the TeleMetrum's on-off switch does NOT control the
145 When the GPS chip is initially searching for
146 satellites, TeleMetrum will consume more current than it can pull
147 from the USB port, so the battery must be attached in order to get
148 satellite lock. Once GPS is locked, the current consumption goes back
149 down enough to enable charging while
150 running. So it's a good idea to fully charge the battery as your
151 first item of business so there is no issue getting and maintaining
152 satellite lock. The yellow charge indicator led will go out when the
153 battery is nearly full and the charger goes to trickle charge. It
154 can take several hours to fully recharge a deeply discharged battery.
157 The TeleMini battery can be charged by disconnecting it from the
158 TeleMini board and plugging it into a standalone battery charger
159 board, and connecting that via a USB cable to a laptop or other USB
163 The other active device in the starter kit is the TeleDongle USB to
164 RF interface. If you plug it in to your Mac or Linux computer it should
165 "just work", showing up as a serial port device. Windows systems need
166 driver information that is part of the AltOS download to know that the
167 existing USB modem driver will work. We therefore recommend installing
168 our software before plugging in TeleDongle if you are using a Windows
169 computer. If you are using Linux and are having problems, try moving
170 to a fresher kernel (2.6.33 or newer), as the USB serial driver had
171 ugly bugs in some earlier versions.
174 Next you should obtain and install the AltOS software. These include
175 the AltosUI ground station program, current firmware images for
176 TeleMetrum, TeleMini and TeleDongle, and a number of standalone
177 utilities that are rarely needed. Pre-built binary packages are
178 available for Linux, Microsoft Windows, and recent MacOSX versions.
179 Full source code and build instructions are also available.
180 The latest version may always be downloaded from
181 <ulink url="http://altusmetrum.org/AltOS"/>.
185 <title>Handling Precautions</title>
187 All Altus Metrum products are sophisticated electronic devices.
188 When handled gently and properly installed in an air-frame, they
189 will deliver impressive results. However, as with all electronic
190 devices, there are some precautions you must take.
193 The Lithium Polymer rechargeable batteries have an
194 extraordinary power density. This is great because we can fly with
195 much less battery mass than if we used alkaline batteries or previous
196 generation rechargeable batteries... but if they are punctured
197 or their leads are allowed to short, they can and will release their
199 Thus we recommend that you take some care when handling our batteries
200 and consider giving them some extra protection in your air-frame. We
201 often wrap them in suitable scraps of closed-cell packing foam before
202 strapping them down, for example.
205 The barometric sensors used on both TeleMetrum and TeleMini are
206 sensitive to sunlight. In normal TeleMetrum mounting situations, it
207 and all of the other surface mount components
208 are "down" towards whatever the underlying mounting surface is, so
209 this is not normally a problem. Please consider this, though, when
210 designing an installation, for example, in an air-frame with a
211 see-through plastic payload bay. It is particularly important to
212 consider this with TeleMini, both because the baro sensor is on the
213 "top" of the board, and because many model rockets with payload bays
214 use clear plastic for the payload bay! Replacing these with an opaque
215 cardboard tube, painting them, or wrapping them with a layer of masking
216 tape are all reasonable approaches to keep the sensor out of direct
220 The barometric sensor sampling port must be able to "breathe",
221 both by not being covered by foam or tape or other materials that might
222 directly block the hole on the top of the sensor, and also by having a
223 suitable static vent to outside air.
226 As with all other rocketry electronics, Altus Metrum altimeters must
227 be protected from exposure to corrosive motor exhaust and ejection
232 <title>Hardware Overview</title>
234 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
235 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
236 small in diameter may require some creativity in mounting and wiring
237 to succeed! The presence of an accelerometer means TeleMetrum should
238 be aligned along the flight axis of the airframe, and by default the 1/4
239 wave UHF wire antenna should be on the nose-cone end of the board. The
240 antenna wire is about 7 inches long, and wiring for a power switch and
241 the e-matches for apogee and main ejection charges depart from the
242 fin can end of the board, meaning an ideal "simple" avionics
243 bay for TeleMetrum should have at least 10 inches of interior length.
246 TeleMini is a 0.5 inch by 1.5 inch circuit board. It was designed to
247 fit inside an 18mm air-frame tube, but using it in a tube that
248 small in diameter may require some creativity in mounting and wiring
249 to succeed! Since there is no accelerometer, TeleMini can be mounted
250 in any convenient orientation. The default 1/4
251 wave UHF wire antenna attached to the center of one end of
252 the board is about 7 inches long, and wiring for a power switch and
253 the e-matches for apogee and main ejection charges depart from the
254 other end of the board, meaning an ideal "simple" avionics
255 bay for TeleMini should have at least 9 inches of interior length.
258 A typical TeleMetrum or TeleMini installation involves attaching
259 only a suitable Lithium Polymer battery, a single pole switch for
260 power on/off, and two pairs of wires connecting e-matches for the
261 apogee and main ejection charges.
264 By default, we use the unregulated output of the Li-Po battery directly
265 to fire ejection charges. This works marvelously with standard
266 low-current e-matches like the J-Tek from MJG Technologies, and with
267 Quest Q2G2 igniters. However, if you want or need to use a separate
268 pyro battery, check out the "External Pyro Battery" section in this
269 manual for instructions on how to wire that up. The altimeters are
270 designed to work with an external pyro battery of no more than 15 volts.
273 Ejection charges are wired directly to the screw terminal block
274 at the aft end of the altimeter. You'll need a very small straight
275 blade screwdriver for these screws, such as you might find in a
276 jeweler's screwdriver set.
279 TeleMetrum also uses the screw terminal block for the power
280 switch leads. On TeleMini, the power switch leads are soldered
281 directly to the board and can be connected directly to a switch.
284 For most air-frames, the integrated antennas are more than
285 adequate. However, if you are installing in a carbon-fiber or
286 metal electronics bay which is opaque to RF signals, you may need to
287 use off-board external antennas instead. In this case, you can
288 order an altimeter with an SMA connector for the UHF antenna
289 connection, and, on TeleMetrum, you can unplug the integrated GPS
290 antenna and select an appropriate off-board GPS antenna with
291 cable terminating in a U.FL connector.
295 <title>System Operation</title>
297 <title>Firmware Modes </title>
299 The AltOS firmware build for the altimeters has two
300 fundamental modes, "idle" and "flight". Which of these modes
301 the firmware operates in is determined at start up time. For
302 TeleMetrum, the mode is controlled by the orientation of the
303 rocket (well, actually the board, of course...) at the time
304 power is switched on. If the rocket is "nose up", then
305 TeleMetrum assumes it's on a rail or rod being prepared for
306 launch, so the firmware chooses flight mode. However, if the
307 rocket is more or less horizontal, the firmware instead enters
308 idle mode. Since TeleMini doesn't have an accelerometer we can
309 use to determine orientation, "idle" mode is selected when the
310 board receives a command packet within the first five seconds
311 of operation; if no packet is received, the board enters
315 At power on, you will hear three beeps or see three flashes
316 ("S" in Morse code for start up) and then a pause while
317 the altimeter completes initialization and self test, and decides
318 which mode to enter next.
321 In flight or "pad" mode, the altimeter engages the flight
322 state machine, goes into transmit-only mode to
323 send telemetry, and waits for launch to be detected.
324 Flight mode is indicated by an "di-dah-dah-dit" ("P" for pad)
325 on the beeper or lights, followed by beeps or flashes
326 indicating the state of the pyrotechnic igniter continuity.
327 One beep/flash indicates apogee continuity, two beeps/flashes
328 indicate main continuity, three beeps/flashes indicate both
329 apogee and main continuity, and one longer "brap" sound or
330 rapidly alternating lights indicates no continuity. For a
331 dual deploy flight, make sure you're getting three beeps or
332 flashes before launching! For apogee-only or motor eject
333 flights, do what makes sense.
336 If idle mode is entered, you will hear an audible "di-dit" or see
337 two short flashes ("I" for idle), and the flight state machine is
338 disengaged, thus no ejection charges will fire. The altimeters also
339 listen for the radio link when in idle mode for requests sent via
340 TeleDongle. Commands can be issued to a TeleMetrum in idle mode
342 USB or the radio link equivalently. TeleMini only has the radio link.
343 Idle mode is useful for configuring the altimeter, for extracting data
344 from the on-board storage chip after flight, and for ground testing
348 One "neat trick" of particular value when TeleMetrum is used with
349 very large air-frames, is that you can power the board up while the
350 rocket is horizontal, such that it comes up in idle mode. Then you can
351 raise the air-frame to launch position, and issue a 'reset' command
352 via TeleDongle over the radio link to cause the altimeter to reboot and
353 come up in flight mode. This is much safer than standing on the top
354 step of a rickety step-ladder or hanging off the side of a launch
355 tower with a screw-driver trying to turn on your avionics before
362 TeleMetrum includes a complete GPS receiver. A complete explanation
363 of how GPS works is beyond the scope of this manual, but the bottom
364 line is that the TeleMetrum GPS receiver needs to lock onto at least
365 four satellites to obtain a solid 3 dimensional position fix and know
369 TeleMetrum provides backup power to the GPS chip any time a
370 battery is connected. This allows the receiver to "warm start" on
371 the launch rail much faster than if every power-on were a GPS
372 "cold start". In typical operations, powering up TeleMetrum
373 on the flight line in idle mode while performing final air-frame
374 preparation will be sufficient to allow the GPS receiver to cold
375 start and acquire lock. Then the board can be powered down during
376 RSO review and installation on a launch rod or rail. When the board
377 is turned back on, the GPS system should lock very quickly, typically
378 long before igniter installation and return to the flight line are
383 <title>Controlling An Altimeter Over The Radio Link</title>
385 One of the unique features of the Altus Metrum system is
386 the ability to create a two way command link between TeleDongle
387 and an altimeter using the digital radio transceivers built into
388 each device. This allows you to interact with the altimeter from
389 afar, as if it were directly connected to the computer.
392 Any operation which can be performed with TeleMetrum can
393 either be done with TeleMetrum directly connected to the
394 computer via the USB cable, or through the radio
395 link. TeleMini doesn't provide a USB connector and so it is
396 always communicated with over radio. Select the appropriate
397 TeleDongle device when the list of devices is presented and
398 AltosUI will interact with an altimeter over the radio link.
401 One oddity in the current interface is how AltosUI selects the
402 frequency for radio communications. Instead of providing
403 an interface to specifically configure the frequency, it uses
404 whatever frequency was most recently selected for the target
405 TeleDongle device in Monitor Flight mode. If you haven't ever
406 used that mode with the TeleDongle in question, select the
407 Monitor Flight button from the top level UI, and pick the
408 appropriate TeleDongle device. Once the flight monitoring
409 window is open, select the desired frequency and then close it
410 down again. All radio communications will now use that frequency.
415 Save Flight Data—Recover flight data from the rocket without
421 Configure altimeter apogee delays or main deploy heights
422 to respond to changing launch conditions. You can also
423 'reboot' the altimeter. Use this to remotely enable the
424 flight computer by turning TeleMetrum on in "idle" mode,
425 then once the air-frame is oriented for launch, you can
426 reboot the altimeter and have it restart in pad mode
427 without having to climb the scary ladder.
432 Fire Igniters—Test your deployment charges without snaking
433 wires out through holes in the air-frame. Simply assembly the
434 rocket as if for flight with the apogee and main charges
435 loaded, then remotely command the altimeter to fire the
441 Operation over the radio link for configuring an altimeter, ground
442 testing igniters, and so forth uses the same RF frequencies as flight
443 telemetry. To configure the desired TeleDongle frequency, select
444 the monitor flight tab, then use the frequency selector and
445 close the window before performing other desired radio operations.
448 TeleMetrum only enables radio commanding in 'idle' mode, so
449 make sure you have TeleMetrum lying horizontally when you turn
450 it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
451 flight, and will not be listening for command packets from TeleDongle.
454 TeleMini listens for a command packet for five seconds after
455 first being turned on, if it doesn't hear anything, it enters
456 'pad' mode, ready for flight and will no longer listen for
457 command packets. The easiest way to connect to TeleMini is to
458 initiate the command and select the TeleDongle device. At this
459 point, the TeleDongle will be attempting to communicate with
460 the TeleMini. Now turn TeleMini on, and it should immediately
461 start communicating with the TeleDongle and the desired
462 operation can be performed.
465 You can monitor the operation of the radio link by watching the
466 lights on the devices. The red LED will flash each time a packet
467 is tramsitted, while the green LED will light up on TeleDongle when
468 it is waiting to receive a packet from the altimeter.
472 <title>Ground Testing </title>
474 An important aspect of preparing a rocket using electronic deployment
475 for flight is ground testing the recovery system. Thanks
476 to the bi-directional radio link central to the Altus Metrum system,
477 this can be accomplished in a TeleMetrum or TeleMini equipped rocket
478 with less work than you may be accustomed to with other systems. It
482 Just prep the rocket for flight, then power up the altimeter
483 in "idle" mode (placing air-frame horizontal for TeleMetrum or
484 selected the Configure Altimeter tab for TeleMini). This will cause
485 the firmware to go into "idle" mode, in which the normal flight
486 state machine is disabled and charges will not fire without
487 manual command. You can now command the altimeter to fire the apogee
488 or main charges from a safe distance using your computer and
489 TeleDongle and the Fire Igniter tab to complete ejection testing.
493 <title>Radio Link </title>
495 The chip our boards are based on incorporates an RF transceiver, but
496 it's not a full duplex system... each end can only be transmitting or
497 receiving at any given moment. So we had to decide how to manage the
501 By design, the altimeter firmware listens for the radio link when
502 it's in "idle mode", which
503 allows us to use the radio link to configure the rocket, do things like
504 ejection tests, and extract data after a flight without having to
505 crack open the air-frame. However, when the board is in "flight
506 mode", the altimeter only
507 transmits and doesn't listen at all. That's because we want to put
508 ultimate priority on event detection and getting telemetry out of
510 the radio in case the rocket crashes and we aren't able to extract
514 We don't use a 'normal packet radio' mode like APRS because they're
515 just too inefficient. The GFSK modulation we use is FSK with the
516 base-band pulses passed through a
517 Gaussian filter before they go into the modulator to limit the
518 transmitted bandwidth. When combined with the hardware forward error
519 correction support in the cc1111 chip, this allows us to have a very
520 robust 38.4 kilobit data link with only 10 milliwatts of transmit
521 power, a whip antenna in the rocket, and a hand-held Yagi on the
522 ground. We've had flights to above 21k feet AGL with great reception,
523 and calculations suggest we should be good to well over 40k feet AGL
524 with a 5-element yagi on the ground. We hope to fly boards to higher
525 altitudes over time, and would of course appreciate customer feedback
526 on performance in higher altitude flights!
530 <title>Configurable Parameters</title>
532 Configuring an Altus Metrum altimeter for flight is very
533 simple. Even on our baro-only TeleMini board, the use of a Kalman
534 filter means there is no need to set a "mach delay". The few
535 configurable parameters can all be set using AltosUI over USB or
536 or radio link via TeleDongle.
539 <title>Radio Frequency</title>
541 Altus Metrum boards support radio frequencies in the 70cm
542 band. By default, the configuration interface provides a
543 list of 10 "standard" frequencies in 100kHz channels starting at
544 434.550MHz. However, the firmware supports use of
545 any 50kHz multiple within the 70cm band. At any given
546 launch, we highly recommend coordinating when and by whom each
547 frequency will be used to avoid interference. And of course, both
548 altimeter and TeleDongle must be configured to the same
549 frequency to successfully communicate with each other.
553 <title>Apogee Delay</title>
555 Apogee delay is the number of seconds after the altimeter detects flight
556 apogee that the drogue charge should be fired. In most cases, this
557 should be left at the default of 0. However, if you are flying
558 redundant electronics such as for an L3 certification, you may wish
559 to set one of your altimeters to a positive delay so that both
560 primary and backup pyrotechnic charges do not fire simultaneously.
563 The Altus Metrum apogee detection algorithm fires exactly at
564 apogee. If you are also flying an altimeter like the
565 PerfectFlite MAWD, which only supports selecting 0 or 1
566 seconds of apogee delay, you may wish to set the MAWD to 0
567 seconds delay and set the TeleMetrum to fire your backup 2
568 or 3 seconds later to avoid any chance of both charges
569 firing simultaneously. We've flown several air-frames this
570 way quite happily, including Keith's successful L3 cert.
574 <title>Main Deployment Altitude</title>
576 By default, the altimeter will fire the main deployment charge at an
577 elevation of 250 meters (about 820 feet) above ground. We think this
578 is a good elevation for most air-frames, but feel free to change this
579 to suit. In particular, if you are flying two altimeters, you may
581 deployment elevation for the backup altimeter to be something lower
582 than the primary so that both pyrotechnic charges don't fire
587 <title>Maximum Flight Log</title>
589 TeleMetrum version 1.1 has 2MB of on-board flash storage,
590 enough to hold over 40 minutes of data at full data rate
591 (100 samples/second). TeleMetrum 1.0 has 1MB of on-board
592 storage. As data are stored at a reduced rate during
593 descent, there's plenty of space to store many flights worth
597 The on-board flash is partitioned into separate flight logs,
598 each of a fixed maximum size. Increase the maximum size of
599 each log and you reduce the number of flights that can be
600 stored. Decrease the size and TeleMetrum can store more
604 All of the configuration data is also stored in the flash
605 memory, which consumes 64kB on TeleMetrum v1.1 and 256B on
606 TeleMetrum v1.0. This configuration space is not available
607 for storing flight log data.
610 To compute the amount of space needed for a single flight,
611 you can multiply the expected ascent time (in seconds) by
612 800, multiply the expected descent time (in seconds) by 80
613 and add the two together. That will slightly under-estimate
614 the storage (in bytes) needed for the flight. For instance,
615 a flight spending 20 seconds in ascent and 150 seconds in
616 descent will take about (20 * 800) + (150 * 80) = 28000
617 bytes of storage. You could store dozens of these flights in
621 The default size, 192kB, allows for 10 flights of storage on
622 TeleMetrum v1.1 and 5 flights on TeleMetrum v1.0. This
623 ensures that you won't need to erase the memory before
624 flying each time while still allowing more than sufficient
625 storage for each flight.
629 <title>Ignite Mode</title>
631 Instead of firing one charge at apogee and another charge at
632 a fixed height above the ground, you can configure the
633 altimeter to fire both at apogee or both during
634 descent. This was added to support an airframe that has two
635 TeleMetrum computers, one in the fin can and one in the
639 Providing the ability to use both igniters for apogee or
640 main allows some level of redundancy without needing two
641 flight computers. In Redundant Apogee or Redundant Main
642 mode, the two charges will be fired two seconds apart.
646 <title>Pad Orientation</title>
648 TeleMetrum measures acceleration along the axis of the
649 board. Which way the board is oriented affects the sign of
650 the acceleration value. Instead of trying to guess which way
651 the board is mounted in the air frame, TeleMetrum must be
652 explicitly configured for either Antenna Up or Antenna
653 Down. The default, Antenna Up, expects the end of the
654 TeleMetrum board connected to the 70cm antenna to be nearest
655 the nose of the rocket, with the end containing the screw
656 terminals nearest the tail.
661 <title>Calibration</title>
663 There are only two calibrations required for a TeleMetrum board, and
664 only one for TeleDongle and TeleMini.
667 <title>Radio Frequency</title>
669 The radio frequency is synthesized from a clock based on the 48 MHz
670 crystal on the board. The actual frequency of this oscillator must be
671 measured to generate a calibration constant. While our GFSK modulation
672 bandwidth is wide enough to allow boards to communicate even when
673 their oscillators are not on exactly the same frequency, performance
674 is best when they are closely matched.
675 Radio frequency calibration requires a calibrated frequency counter.
676 Fortunately, once set, the variation in frequency due to aging and
677 temperature changes is small enough that re-calibration by customers
678 should generally not be required.
681 When the radio calibration value is changed, the radio
682 frequency value is reset to the same value, so you'll need
683 to recompute and reset the radio frequency value using the
684 new radio calibration value.
688 <title>TeleMetrum Accelerometer</title>
690 The TeleMetrum accelerometer we use has its own 5 volt power supply and
691 the output must be passed through a resistive voltage divider to match
692 the input of our 3.3 volt ADC. This means that unlike the barometric
693 sensor, the output of the acceleration sensor is not ratio-metric to
694 the ADC converter, and calibration is required. We also support the
695 use of any of several accelerometers from a Freescale family that
696 includes at least +/- 40g, 50g, 100g, and 200g parts. Using gravity,
697 a simple 2-point calibration yields acceptable results capturing both
698 the different sensitivities and ranges of the different accelerometer
699 parts and any variation in power supply voltages or resistor values
700 in the divider network.
703 To calibrate the acceleration sensor, use the 'c a 0' command. You
704 will be prompted to orient the board vertically with the UHF antenna
705 up and press a key, then to orient the board vertically with the
706 UHF antenna down and press a key.
707 As with all 'c' sub-commands, follow this with a 'c w' to write the
708 change to the parameter block in the on-board DataFlash chip.
711 The +1g and -1g calibration points are included in each telemetry
712 frame and are part of the header extracted by ao-dumplog after flight.
713 Note that we always store and return raw ADC samples for each
714 sensor... nothing is permanently "lost" or "damaged" if the
718 In the unlikely event an accel cal that goes badly, it is possible
719 that TeleMetrum may always come up in 'pad mode' and as such not be
720 listening to either the USB or radio link. If that happens,
721 there is a special hook in the firmware to force the board back
722 in to 'idle mode' so you can re-do the cal. To use this hook, you
723 just need to ground the SPI clock pin at power-on. This pin is
724 available as pin 2 on the 8-pin companion connector, and pin 1 is
725 ground. So either carefully install a fine-gauge wire jumper
726 between the two pins closest to the index hole end of the 8-pin
727 connector, or plug in the programming cable to the 8-pin connector
728 and use a small screwdriver or similar to short the two pins closest
729 to the index post on the 4-pin end of the programming cable, and
730 power up the board. It should come up in 'idle mode' (two beeps).
738 <title>AltosUI</title>
740 The AltosUI program provides a graphical user interface for
741 interacting with the Altus Metrum product family, including
742 TeleMetrum, TeleMini and TeleDongle. AltosUI can monitor telemetry data,
743 configure TeleMetrum, TeleMini and TeleDongle devices and many other
744 tasks. The primary interface window provides a selection of
745 buttons, one for each major activity in the system. This manual
746 is split into chapters, each of which documents one of the tasks
747 provided from the top-level toolbar.
750 <title>Monitor Flight</title>
751 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
753 Selecting this item brings up a dialog box listing all of the
754 connected TeleDongle devices. When you choose one of these,
755 AltosUI will create a window to display telemetry data as
756 received by the selected TeleDongle device.
759 All telemetry data received are automatically recorded in
760 suitable log files. The name of the files includes the current
761 date and rocket serial and flight numbers.
764 The radio frequency being monitored by the TeleDongle device is
765 displayed at the top of the window. You can configure the
766 frequency by clicking on the frequency box and selecting the desired
767 frequency. AltosUI remembers the last frequency selected for each
768 TeleDongle and selects that automatically the next time you use
772 Below the TeleDongle frequency selector, the window contains a few
773 significant pieces of information about the altimeter providing
774 the telemetry data stream:
778 <para>The configured call-sign</para>
781 <para>The device serial number</para>
784 <para>The flight number. Each altimeter remembers how many
790 The rocket flight state. Each flight passes through several
791 states including Pad, Boost, Fast, Coast, Drogue, Main and
797 The Received Signal Strength Indicator value. This lets
798 you know how strong a signal TeleDongle is receiving. The
799 radio inside TeleDongle operates down to about -99dBm;
800 weaker signals may not be receivable. The packet link uses
801 error correction and detection techniques which prevent
802 incorrect data from being reported.
807 Finally, the largest portion of the window contains a set of
808 tabs, each of which contain some information about the rocket.
809 They're arranged in 'flight order' so that as the flight
810 progresses, the selected tab automatically switches to display
811 data relevant to the current state of the flight. You can select
812 other tabs at any time. The final 'table' tab contains all of
813 the telemetry data in one place.
816 <title>Launch Pad</title>
818 The 'Launch Pad' tab shows information used to decide when the
819 rocket is ready for flight. The first elements include red/green
820 indicators, if any of these is red, you'll want to evaluate
821 whether the rocket is ready to launch:
825 Battery Voltage. This indicates whether the Li-Po battery
826 powering the TeleMetrum has sufficient charge to last for
827 the duration of the flight. A value of more than
828 3.7V is required for a 'GO' status.
833 Apogee Igniter Voltage. This indicates whether the apogee
834 igniter has continuity. If the igniter has a low
835 resistance, then the voltage measured here will be close
836 to the Li-Po battery voltage. A value greater than 3.2V is
837 required for a 'GO' status.
842 Main Igniter Voltage. This indicates whether the main
843 igniter has continuity. If the igniter has a low
844 resistance, then the voltage measured here will be close
845 to the Li-Po battery voltage. A value greater than 3.2V is
846 required for a 'GO' status.
851 On-board Data Logging. This indicates whether there is
852 space remaining on-board to store flight data for the
853 upcoming flight. If you've downloaded data, but failed
854 to erase flights, there may not be any space
855 left. TeleMetrum can store multiple flights, depending
856 on the configured maximum flight log size. TeleMini
857 stores only a single flight, so it will need to be
858 downloaded and erased after each flight to capture
859 data. This only affects on-board flight logging; the
860 altimeter will still transmit telemetry and fire
861 ejection charges at the proper times.
866 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
867 currently able to compute position information. GPS requires
868 at least 4 satellites to compute an accurate position.
873 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
874 10 consecutive positions without losing lock. This ensures
875 that the GPS receiver has reliable reception from the
881 The Launchpad tab also shows the computed launch pad position
882 and altitude, averaging many reported positions to improve the
888 <title>Ascent</title>
890 This tab is shown during Boost, Fast and Coast
891 phases. The information displayed here helps monitor the
892 rocket as it heads towards apogee.
895 The height, speed and acceleration are shown along with the
896 maximum values for each of them. This allows you to quickly
897 answer the most commonly asked questions you'll hear during
901 The current latitude and longitude reported by the TeleMetrum GPS are
902 also shown. Note that under high acceleration, these values
903 may not get updated as the GPS receiver loses position
904 fix. Once the rocket starts coasting, the receiver should
905 start reporting position again.
908 Finally, the current igniter voltages are reported as in the
909 Launch Pad tab. This can help diagnose deployment failures
910 caused by wiring which comes loose under high acceleration.
914 <title>Descent</title>
916 Once the rocket has reached apogee and (we hope) activated the
917 apogee charge, attention switches to tracking the rocket on
918 the way back to the ground, and for dual-deploy flights,
919 waiting for the main charge to fire.
922 To monitor whether the apogee charge operated correctly, the
923 current descent rate is reported along with the current
924 height. Good descent rates generally range from 15-30m/s.
927 For TeleMetrum altimeters, you can locate the rocket in the sky
928 using the elevation and
929 bearing information to figure out where to look. Elevation is
930 in degrees above the horizon. Bearing is reported in degrees
931 relative to true north. Range can help figure out how big the
932 rocket will appear. Note that all of these values are relative
933 to the pad location. If the elevation is near 90°, the rocket
934 is over the pad, not over you.
937 Finally, the igniter voltages are reported in this tab as
938 well, both to monitor the main charge as well as to see what
939 the status of the apogee charge is.
943 <title>Landed</title>
945 Once the rocket is on the ground, attention switches to
946 recovery. While the radio signal is generally lost once the
947 rocket is on the ground, the last reported GPS position is
948 generally within a short distance of the actual landing location.
951 The last reported GPS position is reported both by
952 latitude and longitude as well as a bearing and distance from
953 the launch pad. The distance should give you a good idea of
954 whether you'll want to walk or hitch a ride. Take the reported
955 latitude and longitude and enter them into your hand-held GPS
956 unit and have that compute a track to the landing location.
959 Both TeleMini and TeleMetrum will continue to transmit RDF
960 tones after landing, allowing you to locate the rocket by
961 following the radio signal. You may need to get away from
962 the clutter of the flight line, or even get up on a hill (or
963 your neighbor's RV) to receive the RDF signal.
966 The maximum height, speed and acceleration reported
967 during the flight are displayed for your admiring observers.
970 To get more detailed information about the flight, you can
971 click on the 'Graph Flight' button which will bring up a
972 graph window for the current flight.
976 <title>Site Map</title>
978 When the TeleMetrum gets a GPS fix, the Site Map tab will map
979 the rocket's position to make it easier for you to locate the
980 rocket, both while it is in the air, and when it has landed. The
981 rocket's state is indicated by color: white for pad, red for
982 boost, pink for fast, yellow for coast, light blue for drogue,
983 dark blue for main, and black for landed.
986 The map's scale is approximately 3m (10ft) per pixel. The map
987 can be dragged using the left mouse button. The map will attempt
988 to keep the rocket roughly centered while data is being received.
991 Images are fetched automatically via the Google Maps Static API,
992 and are cached for reuse. If map images cannot be downloaded,
993 the rocket's path will be traced on a dark gray background
997 You can pre-load images for your favorite launch sites
998 before you leave home; check out the 'Preload Maps' section below.
1003 <title>Save Flight Data</title>
1005 The altimeter records flight data to its internal flash memory.
1006 The TeleMetrum data is recorded at a much higher rate than the telemetry
1007 system can handle, and is not subject to radio drop-outs. As
1008 such, it provides a more complete and precise record of the
1009 flight. The 'Save Flight Data' button allows you to read the
1010 flash memory and write it to disk. As TeleMini has only a barometer, it
1011 records data at the same rate as the telemetry signal, but there will be
1012 no data lost due to telemetry drop-outs.
1015 Clicking on the 'Save Flight Data' button brings up a list of
1016 connected TeleMetrum and TeleDongle devices. If you select a
1017 TeleMetrum device, the flight data will be downloaded from that
1018 device directly. If you select a TeleDongle device, flight data
1019 will be downloaded from a TeleMetrum or TeleMini device connected via the
1020 packet command link to the specified TeleDongle. See the chapter
1021 on Packet Command Mode for more information about this.
1024 After the device has been selected, a dialog showing the
1025 flight data saved in the device will be shown allowing you to
1026 select which flights to download and which to delete. With
1027 version 0.9 or newer firmware, you must erase flights in order
1028 for the space they consume to be reused by another
1029 flight. This prevents you from accidentally losing flight data
1030 if you neglect to download data before flying again. Note that
1031 if there is no more space available in the device, then no
1032 data will be recorded for a flight.
1035 The file name for each flight log is computed automatically
1036 from the recorded flight date, altimeter serial number and
1037 flight number information.
1041 <title>Replay Flight</title>
1043 Select this button and you are prompted to select a flight
1044 record file, either a .telem file recording telemetry data or a
1045 .eeprom file containing flight data saved from the altimeter
1049 Once a flight record is selected, the flight monitor interface
1050 is displayed and the flight is re-enacted in real time. Check
1051 the Monitor Flight chapter above to learn how this window operates.
1055 <title>Graph Data</title>
1057 Select this button and you are prompted to select a flight
1058 record file, either a .telem file recording telemetry data or a
1059 .eeprom file containing flight data saved from
1063 Once a flight record is selected, a window with two tabs is
1064 opened. The first tab contains a graph with acceleration
1065 (blue), velocity (green) and altitude (red) of the flight are
1066 plotted and displayed, measured in metric units. The
1067 apogee(yellow) and main(magenta) igniter voltages are also
1068 displayed; high voltages indicate continuity, low voltages
1069 indicate open circuits. The second tab contains some basic
1073 The graph can be zoomed into a particular area by clicking and
1074 dragging down and to the right. Once zoomed, the graph can be
1075 reset by clicking and dragging up and to the left. Holding down
1076 control and clicking and dragging allows the graph to be panned.
1077 The right mouse button causes a pop-up menu to be displayed, giving
1078 you the option save or print the plot.
1081 Note that telemetry files will generally produce poor graphs
1082 due to the lower sampling rate and missed telemetry packets.
1083 Use saved flight data for graphing where possible.
1087 <title>Export Data</title>
1089 This tool takes the raw data files and makes them available for
1090 external analysis. When you select this button, you are prompted to select a flight
1091 data file (either .eeprom or .telem will do, remember that
1092 .eeprom files contain higher resolution and more continuous
1093 data). Next, a second dialog appears which is used to select
1094 where to write the resulting file. It has a selector to choose
1095 between CSV and KML file formats.
1098 <title>Comma Separated Value Format</title>
1100 This is a text file containing the data in a form suitable for
1101 import into a spreadsheet or other external data analysis
1102 tool. The first few lines of the file contain the version and
1103 configuration information from the altimeter, then
1104 there is a single header line which labels all of the
1105 fields. All of these lines start with a '#' character which
1106 most tools can be configured to skip over.
1109 The remaining lines of the file contain the data, with each
1110 field separated by a comma and at least one space. All of
1111 the sensor values are converted to standard units, with the
1112 barometric data reported in both pressure, altitude and
1113 height above pad units.
1117 <title>Keyhole Markup Language (for Google Earth)</title>
1119 This is the format used by
1120 Googleearth to provide an overlay within that
1121 application. With this, you can use Googleearth to see the
1122 whole flight path in 3D.
1127 <title>Configure Altimeter</title>
1129 Select this button and then select either a TeleMetrum or
1130 TeleDongle Device from the list provided. Selecting a TeleDongle
1131 device will use Packet Command Mode to configure a remote
1132 altimeter. Learn how to use this in the Packet Command
1136 The first few lines of the dialog provide information about the
1137 connected device, including the product name,
1138 software version and hardware serial number. Below that are the
1139 individual configuration entries.
1142 At the bottom of the dialog, there are four buttons:
1147 Save. This writes any changes to the
1148 configuration parameter block in flash memory. If you don't
1149 press this button, any changes you make will be lost.
1154 Reset. This resets the dialog to the most recently saved values,
1155 erasing any changes you have made.
1160 Reboot. This reboots the device. Use this to
1161 switch from idle to pad mode by rebooting once the rocket is
1162 oriented for flight.
1167 Close. This closes the dialog. Any unsaved changes will be
1173 The rest of the dialog contains the parameters to be configured.
1176 <title>Main Deploy Altitude</title>
1178 This sets the altitude (above the recorded pad altitude) at
1179 which the 'main' igniter will fire. The drop-down menu shows
1180 some common values, but you can edit the text directly and
1181 choose whatever you like. If the apogee charge fires below
1182 this altitude, then the main charge will fire two seconds
1183 after the apogee charge fires.
1187 <title>Apogee Delay</title>
1189 When flying redundant electronics, it's often important to
1190 ensure that multiple apogee charges don't fire at precisely
1191 the same time as that can over pressurize the apogee deployment
1192 bay and cause a structural failure of the air-frame. The Apogee
1193 Delay parameter tells the flight computer to fire the apogee
1194 charge a certain number of seconds after apogee has been
1199 <title>Radio Frequency</title>
1201 This configures which of the configured frequencies to use for both
1202 telemetry and packet command mode. Note that if you set this
1203 value via packet command mode, you will have to reconfigure
1204 the TeleDongle frequency before you will be able to use packet
1209 <title>Radio Calibration</title>
1211 The radios in every Altus Metrum device are calibrated at the
1212 factory to ensure that they transmit and receive on the
1213 specified frequency. You can adjust that
1214 calibration by changing this value. To change the TeleDongle's
1215 calibration, you must reprogram the unit completely.
1219 <title>Callsign</title>
1221 This sets the call sign included in each telemetry packet. Set this
1222 as needed to conform to your local radio regulations.
1226 <title>Maximum Flight Log Size</title>
1228 This sets the space (in kilobytes) allocated for each flight
1229 log. The available space will be divided into chunks of this
1230 size. A smaller value will allow more flights to be stored,
1231 a larger value will record data from longer flights.
1234 During ascent, TeleMetrum records barometer and
1235 accelerometer values 100 times per second, other analog
1236 information (voltages and temperature) 6 times per second
1237 and GPS data once per second. During descent, the non-GPS
1238 data is recorded 1/10th as often. Each barometer +
1239 accelerometer record takes 8 bytes.
1242 The default, 192kB, will store over 200 seconds of data at
1243 the ascent rate, or over 2000 seconds of data at the descent
1244 rate. That's plenty for most flights. This leaves enough
1245 storage for five flights in a 1MB system, or 10 flights in a
1249 The configuration block takes the last available block of
1250 memory, on v1.0 boards that's just 256 bytes. However, the
1251 flash part on the v1.1 boards uses 64kB for each block.
1254 TeleMini has 5kB of on-board storage, which is plenty for a
1255 single flight. Make sure you download and delete the data
1256 before a subsequent flight or it will not log any data.
1260 <title>Ignite Mode</title>
1262 TeleMetrum and TeleMini provide two igniter channels as they
1263 were originally designed as dual-deploy flight
1264 computers. This configuration parameter allows the two
1265 channels to be used in different configurations.
1270 Dual Deploy. This is the usual mode of operation; the
1271 'apogee' channel is fired at apogee and the 'main'
1272 channel at the height above ground specified by the
1273 'Main Deploy Altitude' during descent.
1278 Redundant Apogee. This fires both channels at
1279 apogee, the 'apogee' channel first followed after a two second
1280 delay by the 'main' channel.
1285 Redundant Main. This fires both channels at the
1286 height above ground specified by the Main Deploy
1287 Altitude setting during descent. The 'apogee'
1288 channel is fired first, followed after a two second
1289 delay by the 'main' channel.
1295 <title>Pad Orientation</title>
1297 Because it includes an accelerometer, TeleMetrum is
1298 sensitive to the orientation of the board. By default, it
1299 expects the antenna end to point forward. This parameter
1300 allows that default to be changed, permitting the board to
1301 be mounted with the antenna pointing aft instead.
1306 Antenna Up. In this mode, the antenna end of the
1307 TeleMetrum board must point forward, in line with the
1308 expected flight path.
1313 Antenna Down. In this mode, the antenna end of the
1314 TeleMetrum board must point aft, in line with the
1315 expected flight path.
1322 <title>Configure AltosUI</title>
1324 This button presents a dialog so that you can configure the AltosUI global settings.
1327 <title>Voice Settings</title>
1329 AltosUI provides voice announcements during flight so that you
1330 can keep your eyes on the sky and still get information about
1331 the current flight status. However, sometimes you don't want
1336 <para>Enable—turns all voice announcements on and off</para>
1340 Test Voice—Plays a short message allowing you to verify
1341 that the audio system is working and the volume settings
1348 <title>Log Directory</title>
1350 AltosUI logs all telemetry data and saves all TeleMetrum flash
1351 data to this directory. This directory is also used as the
1352 staring point when selecting data files for display or export.
1355 Click on the directory name to bring up a directory choosing
1356 dialog, select a new directory and click 'Select Directory' to
1357 change where AltosUI reads and writes data files.
1361 <title>Callsign</title>
1363 This value is used in command packet mode and is transmitted
1364 in each packet sent from TeleDongle and received from
1365 TeleMetrum. It is not used in telemetry mode as that transmits
1366 packets only from TeleMetrum to TeleDongle. Configure this
1367 with the AltosUI operators call sign as needed to comply with
1368 your local radio regulations.
1372 <title>Font Size</title>
1374 Selects the set of fonts used in the flight monitor
1375 window. Choose between the small, medium and large sets.
1379 <title>Serial Debug</title>
1381 This causes all communication with a connected device to be
1382 dumped to the console from which AltosUI was started. If
1383 you've started it from an icon or menu entry, the output
1384 will simply be discarded. This mode can be useful to debug
1385 various serial communication issues.
1389 <title>Manage Frequencies</title>
1391 This brings up a dialog where you can configure the set of
1392 frequencies shown in the various frequency menus. You can
1393 add as many as you like, or even reconfigure the default
1394 set. Changing this list does not affect the frequency
1395 settings of any devices, it only changes the set of
1396 frequencies shown in the menus.
1401 <title>Flash Image</title>
1403 This reprograms any Altus Metrum device by using a TeleMetrum
1404 or TeleDongle as a programming dongle. Please read the
1405 directions for flashing devices in the Updating Device
1406 Firmware chapter below.
1409 Once you have the programmer and target devices connected,
1410 push the 'Flash Image' button. That will present a dialog box
1411 listing all of the connected devices. Carefully select the
1412 programmer device, not the device to be programmed.
1415 Next, select the image to flash to the device. These are named
1416 with the product name and firmware version. The file selector
1417 will start in the directory containing the firmware included
1418 with the AltosUI package. Navigate to the directory containing
1419 the desired firmware if it isn't there.
1422 Next, a small dialog containing the device serial number and
1423 RF calibration values should appear. If these values are
1424 incorrect (possibly due to a corrupted image in the device),
1425 enter the correct values here.
1428 Finally, a dialog containing a progress bar will follow the
1429 programming process.
1432 When programming is complete, the target device will
1433 reboot. Note that if the target device is connected via USB, you
1434 will have to unplug it and then plug it back in for the USB
1435 connection to reset so that you can communicate with the device
1440 <title>Fire Igniter</title>
1442 This activates the igniter circuits in TeleMetrum to help test
1443 recovery systems deployment. Because this command can operate
1444 over the Packet Command Link, you can prepare the rocket as
1445 for flight and then test the recovery system without needing
1446 to snake wires inside the air-frame.
1449 Selecting the 'Fire Igniter' button brings up the usual device
1450 selection dialog. Pick the desired TeleDongle or TeleMetrum
1451 device. This brings up another window which shows the current
1452 continuity test status for both apogee and main charges.
1455 Next, select the desired igniter to fire. This will enable the
1459 Select the 'Arm' button. This enables the 'Fire' button. The
1460 word 'Arm' is replaced by a countdown timer indicating that
1461 you have 10 seconds to press the 'Fire' button or the system
1462 will deactivate, at which point you start over again at
1463 selecting the desired igniter.
1467 <title>Scan Channels</title>
1469 This listens for telemetry packets on all of the configured
1470 frequencies, displaying information about each device it
1471 receives a packet from. You can select which of the three
1472 telemetry formats should be tried; by default, it only listens
1473 for the standard telemetry packets used in v1.0 and later
1478 <title>Load Maps</title>
1480 Before heading out to a new launch site, you can use this to
1481 load satellite images in case you don't have internet
1482 connectivity at the site. This loads a fairly large area
1483 around the launch site, which should cover any flight you're likely to make.
1486 There's a drop-down menu of launch sites we know about; if
1487 your favorites aren't there, please let us know the lat/lon
1488 and name of the site. The contents of this list are actually
1489 downloaded at run-time, so as new sites are sent in, they'll
1490 get automatically added to this list.
1493 If the launch site isn't in the list, you can manually enter the lat/lon values
1496 Clicking the 'Load Map' button will fetch images from Google
1497 Maps; note that Google limits how many images you can fetch at
1498 once, so if you load more than one launch site, you may get
1499 some gray areas in the map which indicate that Google is tired
1500 of sending data to you. Try again later.
1504 <title>Monitor Idle</title>
1506 This brings up a dialog similar to the Monitor Flight UI,
1507 except it works with the altimeter in "idle" mode by sending
1508 query commands to discover the current state rather than
1509 listening for telemetry packets.
1514 <title>Using Altus Metrum Products</title>
1516 <title>Being Legal</title>
1518 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
1519 other authorization to legally operate the radio transmitters that are part
1524 <title>In the Rocket</title>
1526 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
1527 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
1528 a Li-Po rechargeable battery. An 860mAh battery weighs less than a 9V
1529 alkaline battery, and will run a TeleMetrum for hours.
1530 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
1531 a few hours, or a TeleMini for much (much) longer.
1534 By default, we ship the altimeters with a simple wire antenna. If your
1535 electronics bay or the air-frame it resides within is made of carbon fiber,
1536 which is opaque to RF signals, you may choose to have an SMA connector
1537 installed so that you can run a coaxial cable to an antenna mounted
1538 elsewhere in the rocket.
1542 <title>On the Ground</title>
1544 To receive the data stream from the rocket, you need an antenna and short
1545 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. The
1546 TeleDongle in turn plugs directly into the USB port on a notebook
1547 computer. Because TeleDongle looks like a simple serial port, your computer
1548 does not require special device drivers... just plug it in.
1551 The GUI tool, AltosUI, is written in Java and runs across
1552 Linux, Mac OS and Windows. There's also a suite of C tools
1553 for Linux which can perform most of the same tasks.
1556 After the flight, you can use the radio link to extract the more detailed data
1557 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
1558 TeleMetrum board directly. Pulling out the data without having to open up
1559 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
1560 battery, so you'll want one of those anyway... the same cable used by lots
1561 of digital cameras and other modern electronic stuff will work fine.
1564 If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
1565 receiver, so that you can put in a way-point for the last reported rocket
1566 position before touch-down. This makes looking for your rocket a lot like
1567 Geo-Caching... just go to the way-point and look around starting from there.
1570 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
1571 can use that with your antenna to direction-find the rocket on the ground
1572 the same way you can use a Walston or Beeline tracker. This can be handy
1573 if the rocket is hiding in sage brush or a tree, or if the last GPS position
1574 doesn't get you close enough because the rocket dropped into a canyon, or
1575 the wind is blowing it across a dry lake bed, or something like that... Keith
1576 and Bdale both currently own and use the Yaesu VX-7R at launches.
1579 So, to recap, on the ground the hardware you'll need includes:
1580 <orderedlist inheritnum='inherit' numeration='arabic'>
1582 an antenna and feed-line
1591 optionally, a hand-held GPS receiver
1594 optionally, an HT or receiver covering 435 MHz
1599 The best hand-held commercial directional antennas we've found for radio
1600 direction finding rockets are from
1601 <ulink url="http://www.arrowantennas.com/" >
1604 The 440-3 and 440-5 are both good choices for finding a
1605 TeleMetrum- or TeleMini- equipped rocket when used with a suitable 70cm HT.
1609 <title>Data Analysis</title>
1611 Our software makes it easy to log the data from each flight, both the
1612 telemetry received during the flight itself, and the more
1613 complete data log recorded in the flash memory on the altimeter
1614 board. Once this data is on your computer, our post-flight tools make it
1615 easy to quickly get to the numbers everyone wants, like apogee altitude,
1616 max acceleration, and max velocity. You can also generate and view a
1617 standard set of plots showing the altitude, acceleration, and
1618 velocity of the rocket during flight. And you can even export a TeleMetrum data file
1619 usable with Google Maps and Google Earth for visualizing the flight path
1620 in two or three dimensions!
1623 Our ultimate goal is to emit a set of files for each flight that can be
1624 published as a web page per flight, or just viewed on your local disk with
1629 <title>Future Plans</title>
1631 In the future, we intend to offer "companion boards" for the rocket that will
1632 plug in to TeleMetrum to collect additional data, provide more pyro channels,
1633 and so forth. A reference design for a companion board will be documented
1634 soon, and will be compatible with open source Arduino programming tools.
1637 We are also working on the design of a hand-held ground terminal that will
1638 allow monitoring the rocket's status, collecting data during flight, and
1639 logging data after flight without the need for a notebook computer on the
1640 flight line. Particularly since it is so difficult to read most notebook
1641 screens in direct sunlight, we think this will be a great thing to have.
1644 Because all of our work is open, both the hardware designs and the software,
1645 if you have some great idea for an addition to the current Altus Metrum family,
1646 feel free to dive in and help! Or let us know what you'd like to see that
1647 we aren't already working on, and maybe we'll get excited about it too...
1652 <title>Altimeter Installation Recommendations</title>
1654 Building high-power rockets that fly safely is hard enough. Mix
1655 in some sophisticated electronics and a bunch of radio energy
1656 and oftentimes you find few perfect solutions. This chapter
1657 contains some suggestions about how to install Altus Metrum
1658 products into the rocket air-frame, including how to safely and
1659 reliably mix a variety of electronics into the same air-frame.
1662 <title>Mounting the Altimeter</title>
1664 The first consideration is to ensure that the altimeter is
1665 securely fastened to the air-frame. For TeleMetrum, we use
1666 nylon standoffs and nylon screws; they're good to at least 50G
1667 and cannot cause any electrical issues on the board. For
1668 TeleMini, we usually cut small pieces of 1/16" balsa to fit
1669 under the screw holes, and then take 2x56 nylon screws and
1670 screw them through the TeleMini mounting holes, through the
1671 balsa and into the underlying material.
1673 <orderedlist inheritnum='inherit' numeration='arabic'>
1675 Make sure TeleMetrum is aligned precisely along the axis of
1676 acceleration so that the accelerometer can accurately
1677 capture data during the flight.
1680 Watch for any metal touching components on the
1681 board. Shorting out connections on the bottom of the board
1682 can cause the altimeter to fail during flight.
1687 <title>Dealing with the Antenna</title>
1689 The antenna supplied is just a piece of solid, insulated,
1690 wire. If it gets damaged or broken, it can be easily
1691 replaced. It should be kept straight and not cut; bending or
1692 cutting it will change the resonant frequency and/or
1693 impedance, making it a less efficient radiator and thus
1694 reducing the range of the telemetry signal.
1697 Keeping metal away from the antenna will provide better range
1698 and a more even radiation pattern. In most rockets, it's not
1699 entirely possible to isolate the antenna from metal
1700 components; there are often bolts, all-thread and wires from other
1701 electronics to contend with. Just be aware that the more stuff
1702 like this around the antenna, the lower the range.
1705 Make sure the antenna is not inside a tube made or covered
1706 with conducting material. Carbon fiber is the most common
1707 culprit here -- CF is a good conductor and will effectively
1708 shield the antenna, dramatically reducing signal strength and
1709 range. Metallic flake paint is another effective shielding
1710 material which is to be avoided around any antennas.
1713 If the ebay is large enough, it can be convenient to simply
1714 mount the altimeter at one end and stretch the antenna out
1715 inside. Taping the antenna to the sled can keep it straight
1716 under acceleration. If there are metal rods, keep the
1717 antenna as far away as possible.
1720 For a shorter ebay, it's quite practical to have the antenna
1721 run through a bulkhead and into an adjacent bay. Drill a small
1722 hole in the bulkhead, pass the antenna wire through it and
1723 then seal it up with glue or clay. We've also used acrylic
1724 tubing to create a cavity for the antenna wire. This works a
1725 bit better in that the antenna is known to stay straight and
1726 not get folded by recovery components in the bay. Angle the
1727 tubing towards the side wall of the rocket and it ends up
1728 consuming very little space.
1731 If you need to place the antenna at a distance from the
1732 altimeter, you can replace the antenna with an edge-mounted
1733 SMA connector, and then run 50Ω coax from the board to the
1734 antenna. Building a remote antenna is beyond the scope of this
1739 <title>Preserving GPS Reception</title>
1741 The GPS antenna and receiver in TeleMetrum are highly
1742 sensitive and normally have no trouble tracking enough
1743 satellites to provide accurate position information for
1744 recovering the rocket. However, there are many ways to
1745 attenuate the GPS signal.
1746 <orderedlist inheritnum='inherit' numeration='arabic'>
1748 Conductive tubing or coatings. Carbon fiber and metal
1749 tubing, or metallic paint will all dramatically attenuate the
1750 GPS signal. We've never heard of anyone successfully
1751 receiving GPS from inside these materials.
1754 Metal components near the GPS patch antenna. These will
1755 de-tune the patch antenna, changing the resonant frequency
1756 away from the L1 carrier and reduce the effectiveness of the
1757 antenna. You can place as much stuff as you like beneath the
1758 antenna as that's covered with a ground plane. But, keep
1759 wires and metal out from above the patch antenna.
1765 <title>Radio Frequency Interference</title>
1767 Any altimeter will generate RFI; the digital circuits use
1768 high-frequency clocks that spray radio interference across a
1769 wide band. Altusmetrum altimeters generate intentional radio
1770 signals as well, increasing the amount of RF energy around the board.
1773 Rocketry altimeters also use precise sensors measuring air
1774 pressure and acceleration. Tiny changes in voltage can cause
1775 these sensor readings to vary by a huge amount. When the
1776 sensors start mis-reporting data, the altimeter can either
1777 fire the igniters at the wrong time, or not fire them at all.
1780 Voltages are induced when radio frequency energy is
1781 transmitted from one circuit to another. Here are things that
1782 increase the induced voltage and current:
1786 Keep wires from different circuits apart. Moving circuits
1787 further apart will reduce RFI.
1790 Avoid parallel wires from different circuits. The longer two
1791 wires run parallel to one another, the larger the amount of
1792 transferred energy. Cross wires at right angles to reduce
1796 Twist wires from the same circuits. Two wires the same
1797 distance from the transmitter will get the same amount of
1798 induced energy which will then cancel out. Any time you have
1799 a wire pair running together, twist the pair together to
1800 even out distances and reduce RFI. For altimeters, this
1801 includes battery leads, switch hookups and igniter
1805 Avoid resonant lengths. Know what frequencies are present
1806 in the environment and avoid having wire lengths near a
1807 natural resonant length. Altusmetrum products transmit on the
1808 70cm amateur band, so you should avoid lengths that are a
1809 simple ratio of that length; essentially any multiple of 1/4
1810 of the wavelength (17.5cm).
1815 <title>The Barometric Sensor</title>
1817 Altusmetrum altimeters measure altitude with a barometric
1818 sensor, essentially measuring the amount of air above the
1819 rocket to figure out how high it is. A large number of
1820 measurements are taken as the altimeter initializes itself to
1821 figure out the pad altitude. Subsequent measurements are then
1822 used to compute the height above the pad.
1825 To accurately measure atmospheric pressure, the ebay
1826 containing the altimeter must be vented outside the
1827 air-frame. The vent must be placed in a region of linear
1828 airflow, smooth and not in an area of increasing or decreasing
1832 The barometric sensor in the altimeter is quite sensitive to
1833 chemical damage from the products of APCP or BP combustion, so
1834 make sure the ebay is carefully sealed from any compartment
1835 which contains ejection charges or motors.
1839 <title>Ground Testing</title>
1841 The most important aspect of any installation is careful
1842 ground testing. Bringing an air-frame up to the LCO table which
1843 hasn't been ground tested can lead to delays or ejection
1844 charges firing on the pad, or, even worse, a recovery system
1848 Do a 'full systems' test that includes wiring up all igniters
1849 without any BP and turning on all of the electronics in flight
1850 mode. This will catch any mistakes in wiring and any residual
1851 RFI issues that might accidentally fire igniters at the wrong
1852 time. Let the air-frame sit for several minutes, checking for
1853 adequate telemetry signal strength and GPS lock.
1856 Ground test the ejection charges. Prepare the rocket for
1857 flight, loading ejection charges and igniters. Completely
1858 assemble the air-frame and then use the 'Fire Igniters'
1859 interface through a TeleDongle to command each charge to
1860 fire. Make sure the charge is sufficient to robustly separate
1861 the air-frame and deploy the recovery system.
1866 <title>Updating Device Firmware</title>
1868 The big conceptual thing to realize is that you have to use a
1869 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
1870 and a TeleMetrum or other TeleDongle to program the TeleDongle
1871 Due to limited memory resources in the cc1111, we don't support
1872 programming directly over USB.
1875 You may wish to begin by ensuring you have current firmware images.
1876 These are distributed as part of the AltOS software bundle that
1877 also includes the AltosUI ground station program. Newer ground
1878 station versions typically work fine with older firmware versions,
1879 so you don't need to update your devices just to try out new
1880 software features. You can always download the most recent
1881 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
1884 We recommend updating the altimeter first, before updating TeleDongle.
1887 <title>Updating TeleMetrum Firmware</title>
1888 <orderedlist inheritnum='inherit' numeration='arabic'>
1890 Find the 'programming cable' that you got as part of the starter
1891 kit, that has a red 8-pin MicroMaTch connector on one end and a
1892 red 4-pin MicroMaTch connector on the other end.
1895 Take the 2 screws out of the TeleDongle case to get access
1896 to the circuit board.
1899 Plug the 8-pin end of the programming cable to the
1900 matching connector on the TeleDongle, and the 4-pin end to the
1901 matching connector on the TeleMetrum.
1902 Note that each MicroMaTch connector has an alignment pin that
1903 goes through a hole in the PC board when you have the cable
1907 Attach a battery to the TeleMetrum board.
1910 Plug the TeleDongle into your computer's USB port, and power
1914 Run AltosUI, and select 'Flash Image' from the File menu.
1917 Pick the TeleDongle device from the list, identifying it as the
1921 Select the image you want put on the TeleMetrum, which should have a
1922 name in the form telemetrum-v1.1-1.0.0.ihx. It should be visible
1923 in the default directory, if not you may have to poke around
1924 your system to find it.
1927 Make sure the configuration parameters are reasonable
1928 looking. If the serial number and/or RF configuration
1929 values aren't right, you'll need to change them.
1932 Hit the 'OK' button and the software should proceed to flash
1933 the TeleMetrum with new firmware, showing a progress bar.
1936 Confirm that the TeleMetrum board seems to have updated OK, which you
1937 can do by plugging in to it over USB and using a terminal program
1938 to connect to the board and issue the 'v' command to check
1942 If something goes wrong, give it another try.
1947 <title>Updating TeleMini Firmware</title>
1948 <orderedlist inheritnum='inherit' numeration='arabic'>
1950 You'll need a special 'programming cable' to reprogram the
1951 TeleMini. It's available on the Altus Metrum web store, or
1952 you can make your own using an 8-pin MicroMaTch connector on
1953 one end and a set of four pins on the other.
1956 Take the 2 screws out of the TeleDongle case to get access
1957 to the circuit board.
1960 Plug the 8-pin end of the programming cable to the matching
1961 connector on the TeleDongle, and the 4-pins into the holes
1962 in the TeleMini circuit board. Note that the MicroMaTch
1963 connector has an alignment pin that goes through a hole in
1964 the PC board when you have the cable oriented correctly, and
1965 that pin 1 on the TeleMini board is marked with a square pad
1966 while the other pins have round pads.
1969 Attach a battery to the TeleMini board.
1972 Plug the TeleDongle into your computer's USB port, and power
1976 Run AltosUI, and select 'Flash Image' from the File menu.
1979 Pick the TeleDongle device from the list, identifying it as the
1983 Select the image you want put on the TeleMini, which should have a
1984 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
1985 in the default directory, if not you may have to poke around
1986 your system to find it.
1989 Make sure the configuration parameters are reasonable
1990 looking. If the serial number and/or RF configuration
1991 values aren't right, you'll need to change them.
1994 Hit the 'OK' button and the software should proceed to flash
1995 the TeleMini with new firmware, showing a progress bar.
1998 Confirm that the TeleMini board seems to have updated OK, which you
1999 can do by configuring it over the radio link through the TeleDongle, or
2000 letting it come up in "flight" mode and listening for telemetry.
2003 If something goes wrong, give it another try.
2008 <title>Updating TeleDongle Firmware</title>
2010 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
2011 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
2013 <orderedlist inheritnum='inherit' numeration='arabic'>
2015 Find the 'programming cable' that you got as part of the starter
2016 kit, that has a red 8-pin MicroMaTch connector on one end and a
2017 red 4-pin MicroMaTch connector on the other end.
2020 Find the USB cable that you got as part of the starter kit, and
2021 plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
2024 Take the 2 screws out of the TeleDongle case to get access
2025 to the circuit board.
2028 Plug the 8-pin end of the programming cable to the
2029 matching connector on the programmer, and the 4-pin end to the
2030 matching connector on the TeleDongle.
2031 Note that each MicroMaTch connector has an alignment pin that
2032 goes through a hole in the PC board when you have the cable
2036 Attach a battery to the TeleMetrum board if you're using one.
2039 Plug both the programmer and the TeleDongle into your computer's USB
2040 ports, and power up the programmer.
2043 Run AltosUI, and select 'Flash Image' from the File menu.
2046 Pick the programmer device from the list, identifying it as the
2050 Select the image you want put on the TeleDongle, which should have a
2051 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
2052 in the default directory, if not you may have to poke around
2053 your system to find it.
2056 Make sure the configuration parameters are reasonable
2057 looking. If the serial number and/or RF configuration
2058 values aren't right, you'll need to change them. The TeleDongle
2059 serial number is on the "bottom" of the circuit board, and can
2060 usually be read through the translucent blue plastic case without
2061 needing to remove the board from the case.
2064 Hit the 'OK' button and the software should proceed to flash
2065 the TeleDongle with new firmware, showing a progress bar.
2068 Confirm that the TeleDongle board seems to have updated OK, which you
2069 can do by plugging in to it over USB and using a terminal program
2070 to connect to the board and issue the 'v' command to check
2071 the version, etc. Once you're happy, remove the programming cable
2072 and put the cover back on the TeleDongle.
2075 If something goes wrong, give it another try.
2079 Be careful removing the programming cable from the locking 8-pin
2080 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
2081 screwdriver or knife blade to gently pry the locking ears out
2082 slightly to extract the connector. We used a locking connector on
2083 TeleMetrum to help ensure that the cabling to companion boards
2084 used in a rocket don't ever come loose accidentally in flight.
2089 <title>Hardware Specifications</title>
2091 <title>TeleMetrum Specifications</title>
2095 Recording altimeter for model rocketry.
2100 Supports dual deployment (can fire 2 ejection charges).
2105 70cm ham-band transceiver for telemetry down-link.
2110 Barometric pressure sensor good to 45k feet MSL.
2115 1-axis high-g accelerometer for motor characterization, capable of
2116 +/- 50g using default part.
2121 On-board, integrated GPS receiver with 5Hz update rate capability.
2126 On-board 1 megabyte non-volatile memory for flight data storage.
2131 USB interface for battery charging, configuration, and data recovery.
2136 Fully integrated support for Li-Po rechargeable batteries.
2141 Uses Li-Po to fire e-matches, can be modified to support
2142 optional separate pyro battery if needed.
2147 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
2153 <title>TeleMini Specifications</title>
2157 Recording altimeter for model rocketry.
2162 Supports dual deployment (can fire 2 ejection charges).
2167 70cm ham-band transceiver for telemetry down-link.
2172 Barometric pressure sensor good to 45k feet MSL.
2177 On-board 5 kilobyte non-volatile memory for flight data storage.
2182 RF interface for battery charging, configuration, and data recovery.
2187 Support for Li-Po rechargeable batteries, using an external charger.
2192 Uses Li-Po to fire e-matches, can be modified to support
2193 optional separate pyro battery if needed.
2198 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
2207 TeleMetrum seems to shut off when disconnected from the
2208 computer. Make sure the battery is adequately charged. Remember the
2209 unit will pull more power than the USB port can deliver before the
2210 GPS enters "locked" mode. The battery charges best when TeleMetrum
2214 It's impossible to stop the TeleDongle when it's in "p" mode, I have
2215 to unplug the USB cable? Make sure you have tried to "escape out" of
2216 this mode. If this doesn't work the reboot procedure for the
2217 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
2218 outgoing buffer IF your "escape out" ('~~') does not work.
2219 At this point using either 'ao-view' (or possibly
2220 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
2224 The amber LED (on the TeleMetrum) lights up when both
2225 battery and USB are connected. Does this mean it's charging?
2226 Yes, the yellow LED indicates the charging at the 'regular' rate.
2227 If the led is out but the unit is still plugged into a USB port,
2228 then the battery is being charged at a 'trickle' rate.
2231 There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
2232 That's the "pad" mode. Weak batteries might be the problem.
2233 It is also possible that the TeleMetrum is horizontal and the output
2234 is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
2235 it received a command packet which would have left it in "pad" mode.
2238 How do I save flight data?
2239 Live telemetry is written to file(s) whenever AltosUI is connected
2240 to the TeleDongle. The file area defaults to ~/TeleMetrum
2241 but is easily changed using the menus in AltosUI. The files that
2242 are written end in '.telem'. The after-flight
2243 data-dumped files will end in .eeprom and represent continuous data
2244 unlike the .telem files that are subject to losses
2245 along the RF data path.
2246 See the above instructions on what and how to save the eeprom stored
2247 data after physically retrieving your altimeter. Make sure to save
2248 the on-board data after each flight; while the TeleMetrum can store
2249 multiple flights, you never know when you'll lose the altimeter...
2253 <title>Notes for Older Software</title>
2256 Before AltosUI was written, using Altus Metrum devices required
2257 some finesse with the Linux command line. There was a limited
2258 GUI tool, ao-view, which provided functionality similar to the
2259 Monitor Flight window in AltosUI, but everything else was a
2260 fairly 80's experience. This appendix includes documentation for
2261 using that software.
2265 Both TeleMetrum and TeleDongle can be directly communicated
2266 with using USB ports. The first thing you should try after getting
2267 both units plugged into to your computer's USB port(s) is to run
2268 'ao-list' from a terminal-window to see what port-device-name each
2269 device has been assigned by the operating system.
2270 You will need this information to access the devices via their
2271 respective on-board firmware and data using other command line
2272 programs in the AltOS software suite.
2275 TeleMini can be communicated with through a TeleDongle device
2276 over the radio link. When first booted, TeleMini listens for a
2277 TeleDongle device and if it receives a packet, it goes into
2278 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
2279 launched. The easiest way to get it talking is to start the
2280 communication link on the TeleDongle and the power up the
2284 To access the device's firmware for configuration you need a terminal
2285 program such as you would use to talk to a modem. The software
2286 authors prefer using the program 'cu' which comes from the UUCP package
2287 on most Unix-like systems such as Linux. An example command line for
2288 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
2289 indicated from running the
2290 ao-list program. Another reasonable terminal program for Linux is
2291 'cutecom'. The default 'escape'
2292 character used by CU (i.e. the character you use to
2293 issue commands to cu itself instead of sending the command as input
2294 to the connected device) is a '~'. You will need this for use in
2295 only two different ways during normal operations. First is to exit
2296 the program by sending a '~.' which is called a 'escape-disconnect'
2297 and allows you to close-out from 'cu'. The
2298 second use will be outlined later.
2301 All of the Altus Metrum devices share the concept of a two level
2302 command set in their firmware.
2303 The first layer has several single letter commands. Once
2304 you are using 'cu' (or 'cutecom') sending (typing) a '?'
2305 returns a full list of these
2306 commands. The second level are configuration sub-commands accessed
2307 using the 'c' command, for
2308 instance typing 'c?' will give you this second level of commands
2309 (all of which require the
2310 letter 'c' to access). Please note that most configuration options
2311 are stored only in Flash memory; TeleDongle doesn't provide any storage
2312 for these options and so they'll all be lost when you unplug it.
2315 Try setting these configuration ('c' or second level menu) values. A good
2316 place to start is by setting your call sign. By default, the boards
2317 use 'N0CALL' which is cute, but not exactly legal!
2318 Spend a few minutes getting comfortable with the units, their
2319 firmware, and 'cu' (or possibly 'cutecom').
2320 For instance, try to send
2321 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
2322 Verify you can connect and disconnect from the units while in your
2323 terminal program by sending the escape-disconnect mentioned above.
2326 To set the radio frequency, use the 'c R' command to specify the
2327 radio transceiver configuration parameter. This parameter is computed
2328 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
2329 the standard calibration reference frequency, 'S', (normally 434.550MHz):
2333 Round the result to the nearest integer value.
2334 As with all 'c' sub-commands, follow this with a 'c w' to write the
2335 change to the parameter block in the on-board flash on
2336 your altimeter board if you want the change to stay in place across reboots.
2339 To set the apogee delay, use the 'c d' command.
2340 As with all 'c' sub-commands, follow this with a 'c w' to write the
2341 change to the parameter block in the on-board DataFlash chip.
2344 To set the main deployment altitude, use the 'c m' command.
2345 As with all 'c' sub-commands, follow this with a 'c w' to write the
2346 change to the parameter block in the on-board DataFlash chip.
2349 To calibrate the radio frequency, connect the UHF antenna port to a
2350 frequency counter, set the board to 434.550MHz, and use the 'C'
2351 command to generate a CW carrier. Wait for the transmitter temperature
2352 to stabilize and the frequency to settle down.
2353 Then, divide 434.550 MHz by the
2354 measured frequency and multiply by the current radio cal value show
2355 in the 'c s' command. For an unprogrammed board, the default value
2356 is 1186611. Take the resulting integer and program it using the 'c f'
2357 command. Testing with the 'C' command again should show a carrier
2358 within a few tens of Hertz of the intended frequency.
2359 As with all 'c' sub-commands, follow this with a 'c w' to write the
2360 change to the parameter block in the on-board DataFlash chip.
2363 Note that the 'reboot' command, which is very useful on the altimeters,
2364 will likely just cause problems with the dongle. The *correct* way
2365 to reset the dongle is just to unplug and re-plug it.
2368 A fun thing to do at the launch site and something you can do while
2369 learning how to use these units is to play with the radio link access
2370 between an altimeter and the TeleDongle. Be aware that you *must* create
2371 some physical separation between the devices, otherwise the link will
2372 not function due to signal overload in the receivers in each device.
2375 Now might be a good time to take a break and read the rest of this
2376 manual, particularly about the two "modes" that the altimeters
2377 can be placed in. TeleMetrum uses the position of the device when booting
2378 up will determine whether the unit is in "pad" or "idle" mode. TeleMini
2379 enters "idle" mode when it receives a command packet within the first 5 seconds
2380 of being powered up, otherwise it enters "pad" mode.
2383 You can access an altimeter in idle mode from the TeleDongle's USB
2384 connection using the radio link
2385 by issuing a 'p' command to the TeleDongle. Practice connecting and
2386 disconnecting ('~~' while using 'cu') from the altimeter. If
2387 you cannot escape out of the "p" command, (by using a '~~' when in
2388 CU) then it is likely that your kernel has issues. Try a newer version.
2391 Using this radio link allows you to configure the altimeter, test
2392 fire e-matches and igniters from the flight line, check pyro-match
2393 continuity and so forth. You can leave the unit turned on while it
2394 is in 'idle mode' and then place the
2395 rocket vertically on the launch pad, walk away and then issue a
2396 reboot command. The altimeter will reboot and start sending data
2397 having changed to the "pad" mode. If the TeleDongle is not receiving
2398 this data, you can disconnect 'cu' from the TeleDongle using the
2399 procedures mentioned above and THEN connect to the TeleDongle from
2400 inside 'ao-view'. If this doesn't work, disconnect from the
2401 TeleDongle, unplug it, and try again after plugging it back in.
2404 In order to reduce the chance of accidental firing of pyrotechnic
2405 charges, the command to fire a charge is intentionally somewhat
2406 difficult to type, and the built-in help is slightly cryptic to
2407 prevent accidental echoing of characters from the help text back at
2408 the board from firing a charge. The command to fire the apogee
2409 drogue charge is 'i DoIt drogue' and the command to fire the main
2410 charge is 'i DoIt main'.
2413 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
2414 and 'ao-view' will both auditorily announce and visually indicate
2416 Now you can launch knowing that you have a good data path and
2417 good satellite lock for flight data and recovery. Remember
2418 you MUST tell ao-view to connect to the TeleDongle explicitly in
2419 order for ao-view to be able to receive data.
2422 The altimeters provide RDF (radio direction finding) tones on
2423 the pad, during descent and after landing. These can be used to
2424 locate the rocket using a directional antenna; the signal
2425 strength providing an indication of the direction from receiver to rocket.
2428 TeleMetrum also provides GPS tracking data, which can further simplify
2429 locating the rocket once it has landed. (The last good GPS data
2430 received before touch-down will be on the data screen of 'ao-view'.)
2433 Once you have recovered the rocket you can download the eeprom
2434 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
2435 either a USB cable or over the radio link using TeleDongle.
2436 And by following the man page for 'ao-postflight' you can create
2437 various data output reports, graphs, and even KML data to see the
2438 flight trajectory in Google-earth. (Moving the viewing angle making
2439 sure to connect the yellow lines while in Google-earth is the proper
2443 As for ao-view.... some things are in the menu but don't do anything
2444 very useful. The developers have stopped working on ao-view to focus
2445 on a new, cross-platform ground station program. So ao-view may or
2446 may not be updated in the future. Mostly you just use
2447 the Log and Device menus. It has a wonderful display of the incoming
2448 flight data and I am sure you will enjoy what it has to say to you
2449 once you enable the voice output!
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