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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 descent
593 (10 samples/second), there's plenty of space to store many
594 flights worth of data.
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.
628 As TeleMini does not contain an accelerometer, it stores
629 data at 10 samples per second during ascent and one sample
630 per second during descent. Each sample is a two byte reading
631 from the barometer. These are stored in 5kB of
632 on-chip flash memory which can hold 256 seconds at the
633 ascent rate or 2560 seconds at the descent rate. Because of
634 the limited storage, TeleMini cannot hold data for more than
635 one flight, and so must be erased after each flight or it
636 will not capture data for subsequent flights.
640 <title>Ignite Mode</title>
642 Instead of firing one charge at apogee and another charge at
643 a fixed height above the ground, you can configure the
644 altimeter to fire both at apogee or both during
645 descent. This was added to support an airframe that has two
646 TeleMetrum computers, one in the fin can and one in the
650 Providing the ability to use both igniters for apogee or
651 main allows some level of redundancy without needing two
652 flight computers. In Redundant Apogee or Redundant Main
653 mode, the two charges will be fired two seconds apart.
657 <title>Pad Orientation</title>
659 TeleMetrum measures acceleration along the axis of the
660 board. Which way the board is oriented affects the sign of
661 the acceleration value. Instead of trying to guess which way
662 the board is mounted in the air frame, TeleMetrum must be
663 explicitly configured for either Antenna Up or Antenna
664 Down. The default, Antenna Up, expects the end of the
665 TeleMetrum board connected to the 70cm antenna to be nearest
666 the nose of the rocket, with the end containing the screw
667 terminals nearest the tail.
675 <title>AltosUI</title>
677 The AltosUI program provides a graphical user interface for
678 interacting with the Altus Metrum product family, including
679 TeleMetrum, TeleMini and TeleDongle. AltosUI can monitor telemetry data,
680 configure TeleMetrum, TeleMini and TeleDongle devices and many other
681 tasks. The primary interface window provides a selection of
682 buttons, one for each major activity in the system. This manual
683 is split into chapters, each of which documents one of the tasks
684 provided from the top-level toolbar.
687 <title>Monitor Flight</title>
688 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
690 Selecting this item brings up a dialog box listing all of the
691 connected TeleDongle devices. When you choose one of these,
692 AltosUI will create a window to display telemetry data as
693 received by the selected TeleDongle device.
696 All telemetry data received are automatically recorded in
697 suitable log files. The name of the files includes the current
698 date and rocket serial and flight numbers.
701 The radio frequency being monitored by the TeleDongle device is
702 displayed at the top of the window. You can configure the
703 frequency by clicking on the frequency box and selecting the desired
704 frequency. AltosUI remembers the last frequency selected for each
705 TeleDongle and selects that automatically the next time you use
709 Below the TeleDongle frequency selector, the window contains a few
710 significant pieces of information about the altimeter providing
711 the telemetry data stream:
715 <para>The configured call-sign</para>
718 <para>The device serial number</para>
721 <para>The flight number. Each altimeter remembers how many
727 The rocket flight state. Each flight passes through several
728 states including Pad, Boost, Fast, Coast, Drogue, Main and
734 The Received Signal Strength Indicator value. This lets
735 you know how strong a signal TeleDongle is receiving. The
736 radio inside TeleDongle operates down to about -99dBm;
737 weaker signals may not be receivable. The packet link uses
738 error correction and detection techniques which prevent
739 incorrect data from being reported.
744 Finally, the largest portion of the window contains a set of
745 tabs, each of which contain some information about the rocket.
746 They're arranged in 'flight order' so that as the flight
747 progresses, the selected tab automatically switches to display
748 data relevant to the current state of the flight. You can select
749 other tabs at any time. The final 'table' tab contains all of
750 the telemetry data in one place.
753 <title>Launch Pad</title>
755 The 'Launch Pad' tab shows information used to decide when the
756 rocket is ready for flight. The first elements include red/green
757 indicators, if any of these is red, you'll want to evaluate
758 whether the rocket is ready to launch:
762 Battery Voltage. This indicates whether the Li-Po battery
763 powering the TeleMetrum has sufficient charge to last for
764 the duration of the flight. A value of more than
765 3.7V is required for a 'GO' status.
770 Apogee Igniter Voltage. This indicates whether the apogee
771 igniter has continuity. If the igniter has a low
772 resistance, then the voltage measured here will be close
773 to the Li-Po battery voltage. A value greater than 3.2V is
774 required for a 'GO' status.
779 Main Igniter Voltage. This indicates whether the main
780 igniter has continuity. If the igniter has a low
781 resistance, then the voltage measured here will be close
782 to the Li-Po battery voltage. A value greater than 3.2V is
783 required for a 'GO' status.
788 On-board Data Logging. This indicates whether there is
789 space remaining on-board to store flight data for the
790 upcoming flight. If you've downloaded data, but failed
791 to erase flights, there may not be any space
792 left. TeleMetrum can store multiple flights, depending
793 on the configured maximum flight log size. TeleMini
794 stores only a single flight, so it will need to be
795 downloaded and erased after each flight to capture
796 data. This only affects on-board flight logging; the
797 altimeter will still transmit telemetry and fire
798 ejection charges at the proper times.
803 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
804 currently able to compute position information. GPS requires
805 at least 4 satellites to compute an accurate position.
810 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
811 10 consecutive positions without losing lock. This ensures
812 that the GPS receiver has reliable reception from the
818 The Launchpad tab also shows the computed launch pad position
819 and altitude, averaging many reported positions to improve the
825 <title>Ascent</title>
827 This tab is shown during Boost, Fast and Coast
828 phases. The information displayed here helps monitor the
829 rocket as it heads towards apogee.
832 The height, speed and acceleration are shown along with the
833 maximum values for each of them. This allows you to quickly
834 answer the most commonly asked questions you'll hear during
838 The current latitude and longitude reported by the TeleMetrum GPS are
839 also shown. Note that under high acceleration, these values
840 may not get updated as the GPS receiver loses position
841 fix. Once the rocket starts coasting, the receiver should
842 start reporting position again.
845 Finally, the current igniter voltages are reported as in the
846 Launch Pad tab. This can help diagnose deployment failures
847 caused by wiring which comes loose under high acceleration.
851 <title>Descent</title>
853 Once the rocket has reached apogee and (we hope) activated the
854 apogee charge, attention switches to tracking the rocket on
855 the way back to the ground, and for dual-deploy flights,
856 waiting for the main charge to fire.
859 To monitor whether the apogee charge operated correctly, the
860 current descent rate is reported along with the current
861 height. Good descent rates generally range from 15-30m/s.
864 For TeleMetrum altimeters, you can locate the rocket in the sky
865 using the elevation and
866 bearing information to figure out where to look. Elevation is
867 in degrees above the horizon. Bearing is reported in degrees
868 relative to true north. Range can help figure out how big the
869 rocket will appear. Note that all of these values are relative
870 to the pad location. If the elevation is near 90°, the rocket
871 is over the pad, not over you.
874 Finally, the igniter voltages are reported in this tab as
875 well, both to monitor the main charge as well as to see what
876 the status of the apogee charge is.
880 <title>Landed</title>
882 Once the rocket is on the ground, attention switches to
883 recovery. While the radio signal is generally lost once the
884 rocket is on the ground, the last reported GPS position is
885 generally within a short distance of the actual landing location.
888 The last reported GPS position is reported both by
889 latitude and longitude as well as a bearing and distance from
890 the launch pad. The distance should give you a good idea of
891 whether you'll want to walk or hitch a ride. Take the reported
892 latitude and longitude and enter them into your hand-held GPS
893 unit and have that compute a track to the landing location.
896 Both TeleMini and TeleMetrum will continue to transmit RDF
897 tones after landing, allowing you to locate the rocket by
898 following the radio signal. You may need to get away from
899 the clutter of the flight line, or even get up on a hill (or
900 your neighbor's RV) to receive the RDF signal.
903 The maximum height, speed and acceleration reported
904 during the flight are displayed for your admiring observers.
907 To get more detailed information about the flight, you can
908 click on the 'Graph Flight' button which will bring up a
909 graph window for the current flight.
913 <title>Site Map</title>
915 When the TeleMetrum gets a GPS fix, the Site Map tab will map
916 the rocket's position to make it easier for you to locate the
917 rocket, both while it is in the air, and when it has landed. The
918 rocket's state is indicated by color: white for pad, red for
919 boost, pink for fast, yellow for coast, light blue for drogue,
920 dark blue for main, and black for landed.
923 The map's scale is approximately 3m (10ft) per pixel. The map
924 can be dragged using the left mouse button. The map will attempt
925 to keep the rocket roughly centered while data is being received.
928 Images are fetched automatically via the Google Maps Static API,
929 and are cached for reuse. If map images cannot be downloaded,
930 the rocket's path will be traced on a dark gray background
934 You can pre-load images for your favorite launch sites
935 before you leave home; check out the 'Preload Maps' section below.
940 <title>Save Flight Data</title>
942 The altimeter records flight data to its internal flash memory.
943 The TeleMetrum data is recorded at a much higher rate than the telemetry
944 system can handle, and is not subject to radio drop-outs. As
945 such, it provides a more complete and precise record of the
946 flight. The 'Save Flight Data' button allows you to read the
947 flash memory and write it to disk. As TeleMini has only a barometer, it
948 records data at the same rate as the telemetry signal, but there will be
949 no data lost due to telemetry drop-outs.
952 Clicking on the 'Save Flight Data' button brings up a list of
953 connected TeleMetrum and TeleDongle devices. If you select a
954 TeleMetrum device, the flight data will be downloaded from that
955 device directly. If you select a TeleDongle device, flight data
956 will be downloaded from a TeleMetrum or TeleMini device connected via the
957 packet command link to the specified TeleDongle. See the chapter
958 on Packet Command Mode for more information about this.
961 After the device has been selected, a dialog showing the
962 flight data saved in the device will be shown allowing you to
963 select which flights to download and which to delete. With
964 version 0.9 or newer firmware, you must erase flights in order
965 for the space they consume to be reused by another
966 flight. This prevents you from accidentally losing flight data
967 if you neglect to download data before flying again. Note that
968 if there is no more space available in the device, then no
969 data will be recorded for a flight.
972 The file name for each flight log is computed automatically
973 from the recorded flight date, altimeter serial number and
974 flight number information.
978 <title>Replay Flight</title>
980 Select this button and you are prompted to select a flight
981 record file, either a .telem file recording telemetry data or a
982 .eeprom file containing flight data saved from the altimeter
986 Once a flight record is selected, the flight monitor interface
987 is displayed and the flight is re-enacted in real time. Check
988 the Monitor Flight chapter above to learn how this window operates.
992 <title>Graph Data</title>
994 Select this button and you are prompted to select a flight
995 record file, either a .telem file recording telemetry data or a
996 .eeprom file containing flight data saved from
1000 Once a flight record is selected, a window with two tabs is
1001 opened. The first tab contains a graph with acceleration
1002 (blue), velocity (green) and altitude (red) of the flight are
1003 plotted and displayed, measured in metric units. The
1004 apogee(yellow) and main(magenta) igniter voltages are also
1005 displayed; high voltages indicate continuity, low voltages
1006 indicate open circuits. The second tab contains some basic
1010 The graph can be zoomed into a particular area by clicking and
1011 dragging down and to the right. Once zoomed, the graph can be
1012 reset by clicking and dragging up and to the left. Holding down
1013 control and clicking and dragging allows the graph to be panned.
1014 The right mouse button causes a pop-up menu to be displayed, giving
1015 you the option save or print the plot.
1018 Note that telemetry files will generally produce poor graphs
1019 due to the lower sampling rate and missed telemetry packets.
1020 Use saved flight data for graphing where possible.
1024 <title>Export Data</title>
1026 This tool takes the raw data files and makes them available for
1027 external analysis. When you select this button, you are prompted to select a flight
1028 data file (either .eeprom or .telem will do, remember that
1029 .eeprom files contain higher resolution and more continuous
1030 data). Next, a second dialog appears which is used to select
1031 where to write the resulting file. It has a selector to choose
1032 between CSV and KML file formats.
1035 <title>Comma Separated Value Format</title>
1037 This is a text file containing the data in a form suitable for
1038 import into a spreadsheet or other external data analysis
1039 tool. The first few lines of the file contain the version and
1040 configuration information from the altimeter, then
1041 there is a single header line which labels all of the
1042 fields. All of these lines start with a '#' character which
1043 most tools can be configured to skip over.
1046 The remaining lines of the file contain the data, with each
1047 field separated by a comma and at least one space. All of
1048 the sensor values are converted to standard units, with the
1049 barometric data reported in both pressure, altitude and
1050 height above pad units.
1054 <title>Keyhole Markup Language (for Google Earth)</title>
1056 This is the format used by
1057 Googleearth to provide an overlay within that
1058 application. With this, you can use Googleearth to see the
1059 whole flight path in 3D.
1064 <title>Configure Altimeter</title>
1066 Select this button and then select either a TeleMetrum or
1067 TeleDongle Device from the list provided. Selecting a TeleDongle
1068 device will use Packet Command Mode to configure a remote
1069 altimeter. Learn how to use this in the Packet Command
1073 The first few lines of the dialog provide information about the
1074 connected device, including the product name,
1075 software version and hardware serial number. Below that are the
1076 individual configuration entries.
1079 At the bottom of the dialog, there are four buttons:
1084 Save. This writes any changes to the
1085 configuration parameter block in flash memory. If you don't
1086 press this button, any changes you make will be lost.
1091 Reset. This resets the dialog to the most recently saved values,
1092 erasing any changes you have made.
1097 Reboot. This reboots the device. Use this to
1098 switch from idle to pad mode by rebooting once the rocket is
1099 oriented for flight.
1104 Close. This closes the dialog. Any unsaved changes will be
1110 The rest of the dialog contains the parameters to be configured.
1113 <title>Main Deploy Altitude</title>
1115 This sets the altitude (above the recorded pad altitude) at
1116 which the 'main' igniter will fire. The drop-down menu shows
1117 some common values, but you can edit the text directly and
1118 choose whatever you like. If the apogee charge fires below
1119 this altitude, then the main charge will fire two seconds
1120 after the apogee charge fires.
1124 <title>Apogee Delay</title>
1126 When flying redundant electronics, it's often important to
1127 ensure that multiple apogee charges don't fire at precisely
1128 the same time as that can over pressurize the apogee deployment
1129 bay and cause a structural failure of the air-frame. The Apogee
1130 Delay parameter tells the flight computer to fire the apogee
1131 charge a certain number of seconds after apogee has been
1136 <title>Radio Frequency</title>
1138 This configures which of the configured frequencies to use for both
1139 telemetry and packet command mode. Note that if you set this
1140 value via packet command mode, you will have to reconfigure
1141 the TeleDongle frequency before you will be able to use packet
1146 <title>Radio Calibration</title>
1148 The radios in every Altus Metrum device are calibrated at the
1149 factory to ensure that they transmit and receive on the
1150 specified frequency. You can adjust that
1151 calibration by changing this value. To change the TeleDongle's
1152 calibration, you must reprogram the unit completely.
1156 <title>Callsign</title>
1158 This sets the call sign included in each telemetry packet. Set this
1159 as needed to conform to your local radio regulations.
1163 <title>Maximum Flight Log Size</title>
1165 This sets the space (in kilobytes) allocated for each flight
1166 log. The available space will be divided into chunks of this
1167 size. A smaller value will allow more flights to be stored,
1168 a larger value will record data from longer flights.
1172 <title>Ignite Mode</title>
1174 TeleMetrum and TeleMini provide two igniter channels as they
1175 were originally designed as dual-deploy flight
1176 computers. This configuration parameter allows the two
1177 channels to be used in different configurations.
1182 Dual Deploy. This is the usual mode of operation; the
1183 'apogee' channel is fired at apogee and the 'main'
1184 channel at the height above ground specified by the
1185 'Main Deploy Altitude' during descent.
1190 Redundant Apogee. This fires both channels at
1191 apogee, the 'apogee' channel first followed after a two second
1192 delay by the 'main' channel.
1197 Redundant Main. This fires both channels at the
1198 height above ground specified by the Main Deploy
1199 Altitude setting during descent. The 'apogee'
1200 channel is fired first, followed after a two second
1201 delay by the 'main' channel.
1207 <title>Pad Orientation</title>
1209 Because it includes an accelerometer, TeleMetrum is
1210 sensitive to the orientation of the board. By default, it
1211 expects the antenna end to point forward. This parameter
1212 allows that default to be changed, permitting the board to
1213 be mounted with the antenna pointing aft instead.
1218 Antenna Up. In this mode, the antenna end of the
1219 TeleMetrum board must point forward, in line with the
1220 expected flight path.
1225 Antenna Down. In this mode, the antenna end of the
1226 TeleMetrum board must point aft, in line with the
1227 expected flight path.
1234 <title>Configure AltosUI</title>
1236 This button presents a dialog so that you can configure the AltosUI global settings.
1239 <title>Voice Settings</title>
1241 AltosUI provides voice announcements during flight so that you
1242 can keep your eyes on the sky and still get information about
1243 the current flight status. However, sometimes you don't want
1248 <para>Enable—turns all voice announcements on and off</para>
1252 Test Voice—Plays a short message allowing you to verify
1253 that the audio system is working and the volume settings
1260 <title>Log Directory</title>
1262 AltosUI logs all telemetry data and saves all TeleMetrum flash
1263 data to this directory. This directory is also used as the
1264 staring point when selecting data files for display or export.
1267 Click on the directory name to bring up a directory choosing
1268 dialog, select a new directory and click 'Select Directory' to
1269 change where AltosUI reads and writes data files.
1273 <title>Callsign</title>
1275 This value is transmitted in each command packet sent from
1276 TeleDongle and received from an altimeter. It is not used in
1277 telemetry mode, as the callsign configured in the altimeter board
1278 is included in all telemetry packets. Configure this
1279 with the AltosUI operators call sign as needed to comply with
1280 your local radio regulations.
1284 <title>Font Size</title>
1286 Selects the set of fonts used in the flight monitor
1287 window. Choose between the small, medium and large sets.
1291 <title>Serial Debug</title>
1293 This causes all communication with a connected device to be
1294 dumped to the console from which AltosUI was started. If
1295 you've started it from an icon or menu entry, the output
1296 will simply be discarded. This mode can be useful to debug
1297 various serial communication issues.
1301 <title>Manage Frequencies</title>
1303 This brings up a dialog where you can configure the set of
1304 frequencies shown in the various frequency menus. You can
1305 add as many as you like, or even reconfigure the default
1306 set. Changing this list does not affect the frequency
1307 settings of any devices, it only changes the set of
1308 frequencies shown in the menus.
1313 <title>Flash Image</title>
1315 This reprograms any Altus Metrum device by using a TeleMetrum
1316 or TeleDongle as a programming dongle. Please read the
1317 directions for flashing devices in the Updating Device
1318 Firmware chapter below.
1321 Once you have the programmer and target devices connected,
1322 push the 'Flash Image' button. That will present a dialog box
1323 listing all of the connected devices. Carefully select the
1324 programmer device, not the device to be programmed.
1327 Next, select the image to flash to the device. These are named
1328 with the product name and firmware version. The file selector
1329 will start in the directory containing the firmware included
1330 with the AltosUI package. Navigate to the directory containing
1331 the desired firmware if it isn't there.
1334 Next, a small dialog containing the device serial number and
1335 RF calibration values should appear. If these values are
1336 incorrect (possibly due to a corrupted image in the device),
1337 enter the correct values here.
1340 Finally, a dialog containing a progress bar will follow the
1341 programming process.
1344 When programming is complete, the target device will
1345 reboot. Note that if the target device is connected via USB, you
1346 will have to unplug it and then plug it back in for the USB
1347 connection to reset so that you can communicate with the device
1352 <title>Fire Igniter</title>
1354 This activates the igniter circuits in TeleMetrum to help test
1355 recovery systems deployment. Because this command can operate
1356 over the Packet Command Link, you can prepare the rocket as
1357 for flight and then test the recovery system without needing
1358 to snake wires inside the air-frame.
1361 Selecting the 'Fire Igniter' button brings up the usual device
1362 selection dialog. Pick the desired TeleDongle or TeleMetrum
1363 device. This brings up another window which shows the current
1364 continuity test status for both apogee and main charges.
1367 Next, select the desired igniter to fire. This will enable the
1371 Select the 'Arm' button. This enables the 'Fire' button. The
1372 word 'Arm' is replaced by a countdown timer indicating that
1373 you have 10 seconds to press the 'Fire' button or the system
1374 will deactivate, at which point you start over again at
1375 selecting the desired igniter.
1379 <title>Scan Channels</title>
1381 This listens for telemetry packets on all of the configured
1382 frequencies, displaying information about each device it
1383 receives a packet from. You can select which of the three
1384 telemetry formats should be tried; by default, it only listens
1385 for the standard telemetry packets used in v1.0 and later
1390 <title>Load Maps</title>
1392 Before heading out to a new launch site, you can use this to
1393 load satellite images in case you don't have internet
1394 connectivity at the site. This loads a fairly large area
1395 around the launch site, which should cover any flight you're likely to make.
1398 There's a drop-down menu of launch sites we know about; if
1399 your favorites aren't there, please let us know the lat/lon
1400 and name of the site. The contents of this list are actually
1401 downloaded at run-time, so as new sites are sent in, they'll
1402 get automatically added to this list.
1405 If the launch site isn't in the list, you can manually enter the lat/lon values
1408 Clicking the 'Load Map' button will fetch images from Google
1409 Maps; note that Google limits how many images you can fetch at
1410 once, so if you load more than one launch site, you may get
1411 some gray areas in the map which indicate that Google is tired
1412 of sending data to you. Try again later.
1416 <title>Monitor Idle</title>
1418 This brings up a dialog similar to the Monitor Flight UI,
1419 except it works with the altimeter in "idle" mode by sending
1420 query commands to discover the current state rather than
1421 listening for telemetry packets.
1426 <title>Using Altus Metrum Products</title>
1428 <title>Being Legal</title>
1430 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
1431 other authorization to legally operate the radio transmitters that are part
1436 <title>In the Rocket</title>
1438 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
1439 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
1440 a Li-Po rechargeable battery. An 860mAh battery weighs less than a 9V
1441 alkaline battery, and will run a TeleMetrum for hours.
1442 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
1443 a few hours, or a TeleMini for much (much) longer.
1446 By default, we ship the altimeters with a simple wire antenna. If your
1447 electronics bay or the air-frame it resides within is made of carbon fiber,
1448 which is opaque to RF signals, you may choose to have an SMA connector
1449 installed so that you can run a coaxial cable to an antenna mounted
1450 elsewhere in the rocket.
1454 <title>On the Ground</title>
1456 To receive the data stream from the rocket, you need an antenna and short
1457 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. The
1458 TeleDongle in turn plugs directly into the USB port on a notebook
1459 computer. Because TeleDongle looks like a simple serial port, your computer
1460 does not require special device drivers... just plug it in.
1463 The GUI tool, AltosUI, is written in Java and runs across
1464 Linux, Mac OS and Windows. There's also a suite of C tools
1465 for Linux which can perform most of the same tasks.
1468 After the flight, you can use the radio link to extract the more detailed data
1469 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
1470 TeleMetrum board directly. Pulling out the data without having to open up
1471 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
1472 battery, so you'll want one of those anyway... the same cable used by lots
1473 of digital cameras and other modern electronic stuff will work fine.
1476 If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
1477 receiver, so that you can put in a way-point for the last reported rocket
1478 position before touch-down. This makes looking for your rocket a lot like
1479 Geo-Caching... just go to the way-point and look around starting from there.
1482 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
1483 can use that with your antenna to direction-find the rocket on the ground
1484 the same way you can use a Walston or Beeline tracker. This can be handy
1485 if the rocket is hiding in sage brush or a tree, or if the last GPS position
1486 doesn't get you close enough because the rocket dropped into a canyon, or
1487 the wind is blowing it across a dry lake bed, or something like that... Keith
1488 and Bdale both currently own and use the Yaesu VX-7R at launches.
1491 So, to recap, on the ground the hardware you'll need includes:
1492 <orderedlist inheritnum='inherit' numeration='arabic'>
1494 an antenna and feed-line
1503 optionally, a hand-held GPS receiver
1506 optionally, an HT or receiver covering 435 MHz
1511 The best hand-held commercial directional antennas we've found for radio
1512 direction finding rockets are from
1513 <ulink url="http://www.arrowantennas.com/" >
1516 The 440-3 and 440-5 are both good choices for finding a
1517 TeleMetrum- or TeleMini- equipped rocket when used with a suitable 70cm HT.
1521 <title>Data Analysis</title>
1523 Our software makes it easy to log the data from each flight, both the
1524 telemetry received during the flight itself, and the more
1525 complete data log recorded in the flash memory on the altimeter
1526 board. Once this data is on your computer, our post-flight tools make it
1527 easy to quickly get to the numbers everyone wants, like apogee altitude,
1528 max acceleration, and max velocity. You can also generate and view a
1529 standard set of plots showing the altitude, acceleration, and
1530 velocity of the rocket during flight. And you can even export a TeleMetrum data file
1531 usable with Google Maps and Google Earth for visualizing the flight path
1532 in two or three dimensions!
1535 Our ultimate goal is to emit a set of files for each flight that can be
1536 published as a web page per flight, or just viewed on your local disk with
1541 <title>Future Plans</title>
1543 In the future, we intend to offer "companion boards" for the rocket that will
1544 plug in to TeleMetrum to collect additional data, provide more pyro channels,
1545 and so forth. A reference design for a companion board will be documented
1546 soon, and will be compatible with open source Arduino programming tools.
1549 We are also working on the design of a hand-held ground terminal that will
1550 allow monitoring the rocket's status, collecting data during flight, and
1551 logging data after flight without the need for a notebook computer on the
1552 flight line. Particularly since it is so difficult to read most notebook
1553 screens in direct sunlight, we think this will be a great thing to have.
1556 Because all of our work is open, both the hardware designs and the software,
1557 if you have some great idea for an addition to the current Altus Metrum family,
1558 feel free to dive in and help! Or let us know what you'd like to see that
1559 we aren't already working on, and maybe we'll get excited about it too...
1564 <title>Altimeter Installation Recommendations</title>
1566 Building high-power rockets that fly safely is hard enough. Mix
1567 in some sophisticated electronics and a bunch of radio energy
1568 and oftentimes you find few perfect solutions. This chapter
1569 contains some suggestions about how to install Altus Metrum
1570 products into the rocket air-frame, including how to safely and
1571 reliably mix a variety of electronics into the same air-frame.
1574 <title>Mounting the Altimeter</title>
1576 The first consideration is to ensure that the altimeter is
1577 securely fastened to the air-frame. For TeleMetrum, we use
1578 nylon standoffs and nylon screws; they're good to at least 50G
1579 and cannot cause any electrical issues on the board. For
1580 TeleMini, we usually cut small pieces of 1/16" balsa to fit
1581 under the screw holes, and then take 2x56 nylon screws and
1582 screw them through the TeleMini mounting holes, through the
1583 balsa and into the underlying material.
1585 <orderedlist inheritnum='inherit' numeration='arabic'>
1587 Make sure TeleMetrum is aligned precisely along the axis of
1588 acceleration so that the accelerometer can accurately
1589 capture data during the flight.
1592 Watch for any metal touching components on the
1593 board. Shorting out connections on the bottom of the board
1594 can cause the altimeter to fail during flight.
1599 <title>Dealing with the Antenna</title>
1601 The antenna supplied is just a piece of solid, insulated,
1602 wire. If it gets damaged or broken, it can be easily
1603 replaced. It should be kept straight and not cut; bending or
1604 cutting it will change the resonant frequency and/or
1605 impedance, making it a less efficient radiator and thus
1606 reducing the range of the telemetry signal.
1609 Keeping metal away from the antenna will provide better range
1610 and a more even radiation pattern. In most rockets, it's not
1611 entirely possible to isolate the antenna from metal
1612 components; there are often bolts, all-thread and wires from other
1613 electronics to contend with. Just be aware that the more stuff
1614 like this around the antenna, the lower the range.
1617 Make sure the antenna is not inside a tube made or covered
1618 with conducting material. Carbon fiber is the most common
1619 culprit here -- CF is a good conductor and will effectively
1620 shield the antenna, dramatically reducing signal strength and
1621 range. Metallic flake paint is another effective shielding
1622 material which is to be avoided around any antennas.
1625 If the ebay is large enough, it can be convenient to simply
1626 mount the altimeter at one end and stretch the antenna out
1627 inside. Taping the antenna to the sled can keep it straight
1628 under acceleration. If there are metal rods, keep the
1629 antenna as far away as possible.
1632 For a shorter ebay, it's quite practical to have the antenna
1633 run through a bulkhead and into an adjacent bay. Drill a small
1634 hole in the bulkhead, pass the antenna wire through it and
1635 then seal it up with glue or clay. We've also used acrylic
1636 tubing to create a cavity for the antenna wire. This works a
1637 bit better in that the antenna is known to stay straight and
1638 not get folded by recovery components in the bay. Angle the
1639 tubing towards the side wall of the rocket and it ends up
1640 consuming very little space.
1643 If you need to place the antenna at a distance from the
1644 altimeter, you can replace the antenna with an edge-mounted
1645 SMA connector, and then run 50Ω coax from the board to the
1646 antenna. Building a remote antenna is beyond the scope of this
1651 <title>Preserving GPS Reception</title>
1653 The GPS antenna and receiver in TeleMetrum are highly
1654 sensitive and normally have no trouble tracking enough
1655 satellites to provide accurate position information for
1656 recovering the rocket. However, there are many ways to
1657 attenuate the GPS signal.
1658 <orderedlist inheritnum='inherit' numeration='arabic'>
1660 Conductive tubing or coatings. Carbon fiber and metal
1661 tubing, or metallic paint will all dramatically attenuate the
1662 GPS signal. We've never heard of anyone successfully
1663 receiving GPS from inside these materials.
1666 Metal components near the GPS patch antenna. These will
1667 de-tune the patch antenna, changing the resonant frequency
1668 away from the L1 carrier and reduce the effectiveness of the
1669 antenna. You can place as much stuff as you like beneath the
1670 antenna as that's covered with a ground plane. But, keep
1671 wires and metal out from above the patch antenna.
1677 <title>Radio Frequency Interference</title>
1679 Any altimeter will generate RFI; the digital circuits use
1680 high-frequency clocks that spray radio interference across a
1681 wide band. Altusmetrum altimeters generate intentional radio
1682 signals as well, increasing the amount of RF energy around the board.
1685 Rocketry altimeters also use precise sensors measuring air
1686 pressure and acceleration. Tiny changes in voltage can cause
1687 these sensor readings to vary by a huge amount. When the
1688 sensors start mis-reporting data, the altimeter can either
1689 fire the igniters at the wrong time, or not fire them at all.
1692 Voltages are induced when radio frequency energy is
1693 transmitted from one circuit to another. Here are things that
1694 increase the induced voltage and current:
1698 Keep wires from different circuits apart. Moving circuits
1699 further apart will reduce RFI.
1702 Avoid parallel wires from different circuits. The longer two
1703 wires run parallel to one another, the larger the amount of
1704 transferred energy. Cross wires at right angles to reduce
1708 Twist wires from the same circuits. Two wires the same
1709 distance from the transmitter will get the same amount of
1710 induced energy which will then cancel out. Any time you have
1711 a wire pair running together, twist the pair together to
1712 even out distances and reduce RFI. For altimeters, this
1713 includes battery leads, switch hookups and igniter
1717 Avoid resonant lengths. Know what frequencies are present
1718 in the environment and avoid having wire lengths near a
1719 natural resonant length. Altusmetrum products transmit on the
1720 70cm amateur band, so you should avoid lengths that are a
1721 simple ratio of that length; essentially any multiple of 1/4
1722 of the wavelength (17.5cm).
1727 <title>The Barometric Sensor</title>
1729 Altusmetrum altimeters measure altitude with a barometric
1730 sensor, essentially measuring the amount of air above the
1731 rocket to figure out how high it is. A large number of
1732 measurements are taken as the altimeter initializes itself to
1733 figure out the pad altitude. Subsequent measurements are then
1734 used to compute the height above the pad.
1737 To accurately measure atmospheric pressure, the ebay
1738 containing the altimeter must be vented outside the
1739 air-frame. The vent must be placed in a region of linear
1740 airflow, smooth and not in an area of increasing or decreasing
1744 The barometric sensor in the altimeter is quite sensitive to
1745 chemical damage from the products of APCP or BP combustion, so
1746 make sure the ebay is carefully sealed from any compartment
1747 which contains ejection charges or motors.
1751 <title>Ground Testing</title>
1753 The most important aspect of any installation is careful
1754 ground testing. Bringing an air-frame up to the LCO table which
1755 hasn't been ground tested can lead to delays or ejection
1756 charges firing on the pad, or, even worse, a recovery system
1760 Do a 'full systems' test that includes wiring up all igniters
1761 without any BP and turning on all of the electronics in flight
1762 mode. This will catch any mistakes in wiring and any residual
1763 RFI issues that might accidentally fire igniters at the wrong
1764 time. Let the air-frame sit for several minutes, checking for
1765 adequate telemetry signal strength and GPS lock.
1768 Ground test the ejection charges. Prepare the rocket for
1769 flight, loading ejection charges and igniters. Completely
1770 assemble the air-frame and then use the 'Fire Igniters'
1771 interface through a TeleDongle to command each charge to
1772 fire. Make sure the charge is sufficient to robustly separate
1773 the air-frame and deploy the recovery system.
1778 <title>Updating Device Firmware</title>
1780 The big conceptual thing to realize is that you have to use a
1781 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
1782 and a TeleMetrum or other TeleDongle to program the TeleDongle
1783 Due to limited memory resources in the cc1111, we don't support
1784 programming directly over USB.
1787 You may wish to begin by ensuring you have current firmware images.
1788 These are distributed as part of the AltOS software bundle that
1789 also includes the AltosUI ground station program. Newer ground
1790 station versions typically work fine with older firmware versions,
1791 so you don't need to update your devices just to try out new
1792 software features. You can always download the most recent
1793 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
1796 We recommend updating the altimeter first, before updating TeleDongle.
1799 <title>Updating TeleMetrum Firmware</title>
1800 <orderedlist inheritnum='inherit' numeration='arabic'>
1802 Find the 'programming cable' that you got as part of the starter
1803 kit, that has a red 8-pin MicroMaTch connector on one end and a
1804 red 4-pin MicroMaTch connector on the other end.
1807 Take the 2 screws out of the TeleDongle case to get access
1808 to the circuit board.
1811 Plug the 8-pin end of the programming cable to the
1812 matching connector on the TeleDongle, and the 4-pin end to the
1813 matching connector on the TeleMetrum.
1814 Note that each MicroMaTch connector has an alignment pin that
1815 goes through a hole in the PC board when you have the cable
1819 Attach a battery to the TeleMetrum board.
1822 Plug the TeleDongle into your computer's USB port, and power
1826 Run AltosUI, and select 'Flash Image' from the File menu.
1829 Pick the TeleDongle device from the list, identifying it as the
1833 Select the image you want put on the TeleMetrum, which should have a
1834 name in the form telemetrum-v1.1-1.0.0.ihx. It should be visible
1835 in the default directory, if not you may have to poke around
1836 your system to find it.
1839 Make sure the configuration parameters are reasonable
1840 looking. If the serial number and/or RF configuration
1841 values aren't right, you'll need to change them.
1844 Hit the 'OK' button and the software should proceed to flash
1845 the TeleMetrum with new firmware, showing a progress bar.
1848 Confirm that the TeleMetrum board seems to have updated OK, which you
1849 can do by plugging in to it over USB and using a terminal program
1850 to connect to the board and issue the 'v' command to check
1854 If something goes wrong, give it another try.
1859 <title>Updating TeleMini Firmware</title>
1860 <orderedlist inheritnum='inherit' numeration='arabic'>
1862 You'll need a special 'programming cable' to reprogram the
1863 TeleMini. It's available on the Altus Metrum web store, or
1864 you can make your own using an 8-pin MicroMaTch connector on
1865 one end and a set of four pins on the other.
1868 Take the 2 screws out of the TeleDongle case to get access
1869 to the circuit board.
1872 Plug the 8-pin end of the programming cable to the matching
1873 connector on the TeleDongle, and the 4-pins into the holes
1874 in the TeleMini circuit board. Note that the MicroMaTch
1875 connector has an alignment pin that goes through a hole in
1876 the PC board when you have the cable oriented correctly, and
1877 that pin 1 on the TeleMini board is marked with a square pad
1878 while the other pins have round pads.
1881 Attach a battery to the TeleMini board.
1884 Plug the TeleDongle into your computer's USB port, and power
1888 Run AltosUI, and select 'Flash Image' from the File menu.
1891 Pick the TeleDongle device from the list, identifying it as the
1895 Select the image you want put on the TeleMini, which should have a
1896 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
1897 in the default directory, if not you may have to poke around
1898 your system to find it.
1901 Make sure the configuration parameters are reasonable
1902 looking. If the serial number and/or RF configuration
1903 values aren't right, you'll need to change them.
1906 Hit the 'OK' button and the software should proceed to flash
1907 the TeleMini with new firmware, showing a progress bar.
1910 Confirm that the TeleMini board seems to have updated OK, which you
1911 can do by configuring it over the radio link through the TeleDongle, or
1912 letting it come up in "flight" mode and listening for telemetry.
1915 If something goes wrong, give it another try.
1920 <title>Updating TeleDongle Firmware</title>
1922 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
1923 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
1925 <orderedlist inheritnum='inherit' numeration='arabic'>
1927 Find the 'programming cable' that you got as part of the starter
1928 kit, that has a red 8-pin MicroMaTch connector on one end and a
1929 red 4-pin MicroMaTch connector on the other end.
1932 Find the USB cable that you got as part of the starter kit, and
1933 plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
1936 Take the 2 screws out of the TeleDongle case to get access
1937 to the circuit board.
1940 Plug the 8-pin end of the programming cable to the
1941 matching connector on the programmer, and the 4-pin end to the
1942 matching connector on the TeleDongle.
1943 Note that each MicroMaTch connector has an alignment pin that
1944 goes through a hole in the PC board when you have the cable
1948 Attach a battery to the TeleMetrum board if you're using one.
1951 Plug both the programmer and the TeleDongle into your computer's USB
1952 ports, and power up the programmer.
1955 Run AltosUI, and select 'Flash Image' from the File menu.
1958 Pick the programmer device from the list, identifying it as the
1962 Select the image you want put on the TeleDongle, which should have a
1963 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
1964 in the default directory, if not you may have to poke around
1965 your system to find it.
1968 Make sure the configuration parameters are reasonable
1969 looking. If the serial number and/or RF configuration
1970 values aren't right, you'll need to change them. The TeleDongle
1971 serial number is on the "bottom" of the circuit board, and can
1972 usually be read through the translucent blue plastic case without
1973 needing to remove the board from the case.
1976 Hit the 'OK' button and the software should proceed to flash
1977 the TeleDongle with new firmware, showing a progress bar.
1980 Confirm that the TeleDongle board seems to have updated OK, which you
1981 can do by plugging in to it over USB and using a terminal program
1982 to connect to the board and issue the 'v' command to check
1983 the version, etc. Once you're happy, remove the programming cable
1984 and put the cover back on the TeleDongle.
1987 If something goes wrong, give it another try.
1991 Be careful removing the programming cable from the locking 8-pin
1992 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
1993 screwdriver or knife blade to gently pry the locking ears out
1994 slightly to extract the connector. We used a locking connector on
1995 TeleMetrum to help ensure that the cabling to companion boards
1996 used in a rocket don't ever come loose accidentally in flight.
2001 <title>Hardware Specifications</title>
2003 <title>TeleMetrum Specifications</title>
2007 Recording altimeter for model rocketry.
2012 Supports dual deployment (can fire 2 ejection charges).
2017 70cm ham-band transceiver for telemetry down-link.
2022 Barometric pressure sensor good to 45k feet MSL.
2027 1-axis high-g accelerometer for motor characterization, capable of
2028 +/- 50g using default part.
2033 On-board, integrated GPS receiver with 5Hz update rate capability.
2038 On-board 1 megabyte non-volatile memory for flight data storage.
2043 USB interface for battery charging, configuration, and data recovery.
2048 Fully integrated support for Li-Po rechargeable batteries.
2053 Uses Li-Po to fire e-matches, can be modified to support
2054 optional separate pyro battery if needed.
2059 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
2065 <title>TeleMini Specifications</title>
2069 Recording altimeter for model rocketry.
2074 Supports dual deployment (can fire 2 ejection charges).
2079 70cm ham-band transceiver for telemetry down-link.
2084 Barometric pressure sensor good to 45k feet MSL.
2089 On-board 5 kilobyte non-volatile memory for flight data storage.
2094 RF interface for battery charging, configuration, and data recovery.
2099 Support for Li-Po rechargeable batteries, using an external charger.
2104 Uses Li-Po to fire e-matches, can be modified to support
2105 optional separate pyro battery if needed.
2110 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
2119 TeleMetrum seems to shut off when disconnected from the
2120 computer. Make sure the battery is adequately charged. Remember the
2121 unit will pull more power than the USB port can deliver before the
2122 GPS enters "locked" mode. The battery charges best when TeleMetrum
2126 It's impossible to stop the TeleDongle when it's in "p" mode, I have
2127 to unplug the USB cable? Make sure you have tried to "escape out" of
2128 this mode. If this doesn't work the reboot procedure for the
2129 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
2130 outgoing buffer IF your "escape out" ('~~') does not work.
2131 At this point using either 'ao-view' (or possibly
2132 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
2136 The amber LED (on the TeleMetrum) lights up when both
2137 battery and USB are connected. Does this mean it's charging?
2138 Yes, the yellow LED indicates the charging at the 'regular' rate.
2139 If the led is out but the unit is still plugged into a USB port,
2140 then the battery is being charged at a 'trickle' rate.
2143 There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
2144 That's the "pad" mode. Weak batteries might be the problem.
2145 It is also possible that the TeleMetrum is horizontal and the output
2146 is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
2147 it received a command packet which would have left it in "pad" mode.
2150 How do I save flight data?
2151 Live telemetry is written to file(s) whenever AltosUI is connected
2152 to the TeleDongle. The file area defaults to ~/TeleMetrum
2153 but is easily changed using the menus in AltosUI. The files that
2154 are written end in '.telem'. The after-flight
2155 data-dumped files will end in .eeprom and represent continuous data
2156 unlike the .telem files that are subject to losses
2157 along the RF data path.
2158 See the above instructions on what and how to save the eeprom stored
2159 data after physically retrieving your altimeter. Make sure to save
2160 the on-board data after each flight; while the TeleMetrum can store
2161 multiple flights, you never know when you'll lose the altimeter...
2165 <title>Notes for Older Software</title>
2168 Before AltosUI was written, using Altus Metrum devices required
2169 some finesse with the Linux command line. There was a limited
2170 GUI tool, ao-view, which provided functionality similar to the
2171 Monitor Flight window in AltosUI, but everything else was a
2172 fairly 80's experience. This appendix includes documentation for
2173 using that software.
2177 Both TeleMetrum and TeleDongle can be directly communicated
2178 with using USB ports. The first thing you should try after getting
2179 both units plugged into to your computer's USB port(s) is to run
2180 'ao-list' from a terminal-window to see what port-device-name each
2181 device has been assigned by the operating system.
2182 You will need this information to access the devices via their
2183 respective on-board firmware and data using other command line
2184 programs in the AltOS software suite.
2187 TeleMini can be communicated with through a TeleDongle device
2188 over the radio link. When first booted, TeleMini listens for a
2189 TeleDongle device and if it receives a packet, it goes into
2190 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
2191 launched. The easiest way to get it talking is to start the
2192 communication link on the TeleDongle and the power up the
2196 To access the device's firmware for configuration you need a terminal
2197 program such as you would use to talk to a modem. The software
2198 authors prefer using the program 'cu' which comes from the UUCP package
2199 on most Unix-like systems such as Linux. An example command line for
2200 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
2201 indicated from running the
2202 ao-list program. Another reasonable terminal program for Linux is
2203 'cutecom'. The default 'escape'
2204 character used by CU (i.e. the character you use to
2205 issue commands to cu itself instead of sending the command as input
2206 to the connected device) is a '~'. You will need this for use in
2207 only two different ways during normal operations. First is to exit
2208 the program by sending a '~.' which is called a 'escape-disconnect'
2209 and allows you to close-out from 'cu'. The
2210 second use will be outlined later.
2213 All of the Altus Metrum devices share the concept of a two level
2214 command set in their firmware.
2215 The first layer has several single letter commands. Once
2216 you are using 'cu' (or 'cutecom') sending (typing) a '?'
2217 returns a full list of these
2218 commands. The second level are configuration sub-commands accessed
2219 using the 'c' command, for
2220 instance typing 'c?' will give you this second level of commands
2221 (all of which require the
2222 letter 'c' to access). Please note that most configuration options
2223 are stored only in Flash memory; TeleDongle doesn't provide any storage
2224 for these options and so they'll all be lost when you unplug it.
2227 Try setting these configuration ('c' or second level menu) values. A good
2228 place to start is by setting your call sign. By default, the boards
2229 use 'N0CALL' which is cute, but not exactly legal!
2230 Spend a few minutes getting comfortable with the units, their
2231 firmware, and 'cu' (or possibly 'cutecom').
2232 For instance, try to send
2233 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
2234 Verify you can connect and disconnect from the units while in your
2235 terminal program by sending the escape-disconnect mentioned above.
2238 To set the radio frequency, use the 'c R' command to specify the
2239 radio transceiver configuration parameter. This parameter is computed
2240 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
2241 the standard calibration reference frequency, 'S', (normally 434.550MHz):
2245 Round the result to the nearest integer value.
2246 As with all 'c' sub-commands, follow this with a 'c w' to write the
2247 change to the parameter block in the on-board flash on
2248 your altimeter board if you want the change to stay in place across reboots.
2251 To set the apogee delay, use the 'c d' command.
2252 As with all 'c' sub-commands, follow this with a 'c w' to write the
2253 change to the parameter block in the on-board DataFlash chip.
2256 To set the main deployment altitude, use the 'c m' command.
2257 As with all 'c' sub-commands, follow this with a 'c w' to write the
2258 change to the parameter block in the on-board DataFlash chip.
2261 To calibrate the radio frequency, connect the UHF antenna port to a
2262 frequency counter, set the board to 434.550MHz, and use the 'C'
2263 command to generate a CW carrier. Wait for the transmitter temperature
2264 to stabilize and the frequency to settle down.
2265 Then, divide 434.550 MHz by the
2266 measured frequency and multiply by the current radio cal value show
2267 in the 'c s' command. For an unprogrammed board, the default value
2268 is 1186611. Take the resulting integer and program it using the 'c f'
2269 command. Testing with the 'C' command again should show a carrier
2270 within a few tens of Hertz of the intended frequency.
2271 As with all 'c' sub-commands, follow this with a 'c w' to write the
2272 change to the parameter block in the on-board DataFlash chip.
2275 Note that the 'reboot' command, which is very useful on the altimeters,
2276 will likely just cause problems with the dongle. The *correct* way
2277 to reset the dongle is just to unplug and re-plug it.
2280 A fun thing to do at the launch site and something you can do while
2281 learning how to use these units is to play with the radio link access
2282 between an altimeter and the TeleDongle. Be aware that you *must* create
2283 some physical separation between the devices, otherwise the link will
2284 not function due to signal overload in the receivers in each device.
2287 Now might be a good time to take a break and read the rest of this
2288 manual, particularly about the two "modes" that the altimeters
2289 can be placed in. TeleMetrum uses the position of the device when booting
2290 up will determine whether the unit is in "pad" or "idle" mode. TeleMini
2291 enters "idle" mode when it receives a command packet within the first 5 seconds
2292 of being powered up, otherwise it enters "pad" mode.
2295 You can access an altimeter in idle mode from the TeleDongle's USB
2296 connection using the radio link
2297 by issuing a 'p' command to the TeleDongle. Practice connecting and
2298 disconnecting ('~~' while using 'cu') from the altimeter. If
2299 you cannot escape out of the "p" command, (by using a '~~' when in
2300 CU) then it is likely that your kernel has issues. Try a newer version.
2303 Using this radio link allows you to configure the altimeter, test
2304 fire e-matches and igniters from the flight line, check pyro-match
2305 continuity and so forth. You can leave the unit turned on while it
2306 is in 'idle mode' and then place the
2307 rocket vertically on the launch pad, walk away and then issue a
2308 reboot command. The altimeter will reboot and start sending data
2309 having changed to the "pad" mode. If the TeleDongle is not receiving
2310 this data, you can disconnect 'cu' from the TeleDongle using the
2311 procedures mentioned above and THEN connect to the TeleDongle from
2312 inside 'ao-view'. If this doesn't work, disconnect from the
2313 TeleDongle, unplug it, and try again after plugging it back in.
2316 In order to reduce the chance of accidental firing of pyrotechnic
2317 charges, the command to fire a charge is intentionally somewhat
2318 difficult to type, and the built-in help is slightly cryptic to
2319 prevent accidental echoing of characters from the help text back at
2320 the board from firing a charge. The command to fire the apogee
2321 drogue charge is 'i DoIt drogue' and the command to fire the main
2322 charge is 'i DoIt main'.
2325 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
2326 and 'ao-view' will both auditorily announce and visually indicate
2328 Now you can launch knowing that you have a good data path and
2329 good satellite lock for flight data and recovery. Remember
2330 you MUST tell ao-view to connect to the TeleDongle explicitly in
2331 order for ao-view to be able to receive data.
2334 The altimeters provide RDF (radio direction finding) tones on
2335 the pad, during descent and after landing. These can be used to
2336 locate the rocket using a directional antenna; the signal
2337 strength providing an indication of the direction from receiver to rocket.
2340 TeleMetrum also provides GPS tracking data, which can further simplify
2341 locating the rocket once it has landed. (The last good GPS data
2342 received before touch-down will be on the data screen of 'ao-view'.)
2345 Once you have recovered the rocket you can download the eeprom
2346 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
2347 either a USB cable or over the radio link using TeleDongle.
2348 And by following the man page for 'ao-postflight' you can create
2349 various data output reports, graphs, and even KML data to see the
2350 flight trajectory in Google-earth. (Moving the viewing angle making
2351 sure to connect the yellow lines while in Google-earth is the proper
2355 As for ao-view.... some things are in the menu but don't do anything
2356 very useful. The developers have stopped working on ao-view to focus
2357 on a new, cross-platform ground station program. So ao-view may or
2358 may not be updated in the future. Mostly you just use
2359 the Log and Device menus. It has a wonderful display of the incoming
2360 flight data and I am sure you will enjoy what it has to say to you
2361 once you enable the voice output!
2365 <title>Calibration</title>
2367 There are only two calibrations required for a TeleMetrum board, and
2368 only one for TeleDongle and TeleMini. All boards are shipped from
2369 the factory pre-calibrated, but the procedures are documented here
2370 in case they are ever needed. Re-calibration is not supported by
2371 AltosUI, you must connect to the board with a serial terminal program
2372 and interact directly with the on-board command interpreter to effect
2376 <title>Radio Frequency</title>
2378 The radio frequency is synthesized from a clock based on the 48 MHz
2379 crystal on the board. The actual frequency of this oscillator
2380 must be measured to generate a calibration constant. While our
2382 bandwidth is wide enough to allow boards to communicate even when
2383 their oscillators are not on exactly the same frequency, performance
2384 is best when they are closely matched.
2385 Radio frequency calibration requires a calibrated frequency counter.
2386 Fortunately, once set, the variation in frequency due to aging and
2387 temperature changes is small enough that re-calibration by customers
2388 should generally not be required.
2391 To calibrate the radio frequency, connect the UHF antenna port to a
2392 frequency counter, set the board to 434.550MHz, and use the 'C'
2393 command in the on-board command interpreter to generate a CW
2394 carrier. For TeleMetrum, this is best done over USB. For TeleMini,
2395 note that the only way to escape the 'C' command is via power cycle
2396 since the board will no longer be listening for commands once it
2397 starts generating a CW carrier.
2400 Wait for the transmitter temperature to stabilize and the frequency
2401 to settle down. Then, divide 434.550 MHz by the
2402 measured frequency and multiply by the current radio cal value show
2403 in the 'c s' command. For an unprogrammed board, the default value
2404 is 1186611. Take the resulting integer and program it using the 'c f'
2405 command. Testing with the 'C' command again should show a carrier
2406 within a few tens of Hertz of the intended frequency.
2407 As with all 'c' sub-commands, follow this with a 'c w' to write the
2408 change to the parameter block in the on-board DataFlash chip.
2411 Note that any time you re-do the radio frequency calibration, the
2412 radio frequency is reset to the default 434.550 Mhz. If you want
2413 to use another frequency, you will have to set that again after
2414 calibration is completed.
2418 <title>TeleMetrum Accelerometer</title>
2420 The TeleMetrum accelerometer we use has its own 5 volt power
2422 the output must be passed through a resistive voltage divider to match
2423 the input of our 3.3 volt ADC. This means that unlike the barometric
2424 sensor, the output of the acceleration sensor is not ratio-metric to
2425 the ADC converter, and calibration is required. Explicitly
2426 calibrating the accelerometers also allows us to load any device
2427 from a Freescale family that includes at least +/- 40g, 50g, 100g,
2428 and 200g parts. Using gravity,
2429 a simple 2-point calibration yields acceptable results capturing both
2430 the different sensitivities and ranges of the different accelerometer
2431 parts and any variation in power supply voltages or resistor values
2432 in the divider network.
2435 To calibrate the acceleration sensor, use the 'c a 0' command. You
2436 will be prompted to orient the board vertically with the UHF antenna
2437 up and press a key, then to orient the board vertically with the
2438 UHF antenna down and press a key. Note that the accuracy of this
2439 calibration depends primarily on how perfectly vertical and still
2440 the board is held during the cal process. As with all 'c'
2441 sub-commands, follow this with a 'c w' to write the
2442 change to the parameter block in the on-board DataFlash chip.
2445 The +1g and -1g calibration points are included in each telemetry
2446 frame and are part of the header stored in onboard flash to be
2447 downloaded after flight. We always store and return raw ADC
2448 samples for each sensor... so nothing is permanently "lost" or
2449 "damaged" if the calibration is poor.
2452 In the unlikely event an accel cal goes badly, it is possible
2453 that TeleMetrum may always come up in 'pad mode' and as such not be
2454 listening to either the USB or radio link. If that happens,
2455 there is a special hook in the firmware to force the board back
2456 in to 'idle mode' so you can re-do the cal. To use this hook, you
2457 just need to ground the SPI clock pin at power-on. This pin is
2458 available as pin 2 on the 8-pin companion connector, and pin 1 is
2459 ground. So either carefully install a fine-gauge wire jumper
2460 between the two pins closest to the index hole end of the 8-pin
2461 connector, or plug in the programming cable to the 8-pin connector
2462 and use a small screwdriver or similar to short the two pins closest
2463 to the index post on the 4-pin end of the programming cable, and
2464 power up the board. It should come up in 'idle mode' (two beeps),
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