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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>1.1.1</revnumber>
40 <date>16 September 2012</date>
42 Updated for software version 1.1.1 Version 1.1.1 fixes a few
43 bugs found in version 1.1.
47 <revnumber>1.1</revnumber>
48 <date>13 September 2012</date>
50 Updated for software version 1.1. Version 1.1 has new
51 features but is otherwise compatible with version 1.0.
55 <revnumber>1.0</revnumber>
56 <date>24 August 2011</date>
58 Updated for software version 1.0. Note that 1.0 represents a
59 telemetry format change, meaning both ends of a link
60 (TeleMetrum/TeleMini and TeleDongle) must be updated or
61 communications will fail.
65 <revnumber>0.9</revnumber>
66 <date>18 January 2011</date>
68 Updated for software version 0.9. Note that 0.9 represents a
69 telemetry format change, meaning both ends of a link (TeleMetrum and
70 TeleDongle) must be updated or communications will fail.
74 <revnumber>0.8</revnumber>
75 <date>24 November 2010</date>
76 <revremark>Updated for software version 0.8 </revremark>
82 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing "The
83 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
84 Kit" which formed the basis of the original Getting Started chapter
85 in this manual. Bob was one of our first customers for a production
86 TeleMetrum, and his continued enthusiasm and contributions
87 are immensely gratifying and highly appreciated!
90 And thanks to Anthony (AJ) Towns for major contributions including
91 the AltosUI graphing and site map code and associated documentation.
92 Free software means that our customers and friends can become our
93 collaborators, and we certainly appreciate this level of
97 Have fun using these products, and we hope to meet all of you
98 out on the rocket flight line somewhere.
101 NAR #87103, TRA #12201
103 Keith Packard, KD7SQG
104 NAR #88757, TRA #12200
109 <title>Introduction and Overview</title>
111 Welcome to the Altus Metrum community! Our circuits and software reflect
112 our passion for both hobby rocketry and Free Software. We hope their
113 capabilities and performance will delight you in every way, but by
114 releasing all of our hardware and software designs under open licenses,
115 we also hope to empower you to take as active a role in our collective
119 The first device created for our community was TeleMetrum, a dual
120 deploy altimeter with fully integrated GPS and radio telemetry
121 as standard features, and a "companion interface" that will
122 support optional capabilities in the future.
125 The newest device is TeleMini, a dual deploy altimeter with
126 radio telemetry and radio direction finding. This device is only
127 13mm by 38mm (½ inch by 1½ inches) and can fit easily in an 18mm
131 Complementing TeleMetrum and TeleMini is TeleDongle, a USB to RF
132 interface for communicating with the altimeters. Combined with your
133 choice of antenna and
134 notebook computer, TeleDongle and our associated user interface software
135 form a complete ground station capable of logging and displaying in-flight
136 telemetry, aiding rocket recovery, then processing and archiving flight
137 data for analysis and review.
140 More products will be added to the Altus Metrum family over time, and
141 we currently envision that this will be a single, comprehensive manual
142 for the entire product family.
146 <title>Getting Started</title>
148 The first thing to do after you check the inventory of parts in your
149 "starter kit" is to charge the battery.
152 The TeleMetrum battery can be charged by plugging it into the
153 corresponding socket of the TeleMetrum and then using the USB A to
155 cable to plug the TeleMetrum into your computer's USB socket. The
156 TeleMetrum circuitry will charge the battery whenever it is plugged
157 in, because the TeleMetrum's on-off switch does NOT control the
161 When the GPS chip is initially searching for
162 satellites, TeleMetrum will consume more current than it can pull
163 from the USB port, so the battery must be attached in order to get
164 satellite lock. Once GPS is locked, the current consumption goes back
165 down enough to enable charging while
166 running. So it's a good idea to fully charge the battery as your
167 first item of business so there is no issue getting and maintaining
168 satellite lock. The yellow charge indicator led will go out when the
169 battery is nearly full and the charger goes to trickle charge. It
170 can take several hours to fully recharge a deeply discharged battery.
173 The TeleMini battery can be charged by disconnecting it from the
174 TeleMini board and plugging it into a standalone battery charger
175 board, and connecting that via a USB cable to a laptop or other USB
179 The other active device in the starter kit is the TeleDongle USB to
180 RF interface. If you plug it in to your Mac or Linux computer it should
181 "just work", showing up as a serial port device. Windows systems need
182 driver information that is part of the AltOS download to know that the
183 existing USB modem driver will work. We therefore recommend installing
184 our software before plugging in TeleDongle if you are using a Windows
185 computer. If you are using Linux and are having problems, try moving
186 to a fresher kernel (2.6.33 or newer), as the USB serial driver had
187 ugly bugs in some earlier versions.
190 Next you should obtain and install the AltOS software. These include
191 the AltosUI ground station program, current firmware images for
192 TeleMetrum, TeleMini and TeleDongle, and a number of standalone
193 utilities that are rarely needed. Pre-built binary packages are
194 available for Linux, Microsoft Windows, and recent MacOSX versions.
195 Full source code and build instructions are also available.
196 The latest version may always be downloaded from
197 <ulink url="http://altusmetrum.org/AltOS"/>.
201 <title>Handling Precautions</title>
203 All Altus Metrum products are sophisticated electronic devices.
204 When handled gently and properly installed in an air-frame, they
205 will deliver impressive results. However, as with all electronic
206 devices, there are some precautions you must take.
209 The Lithium Polymer rechargeable batteries have an
210 extraordinary power density. This is great because we can fly with
211 much less battery mass than if we used alkaline batteries or previous
212 generation rechargeable batteries... but if they are punctured
213 or their leads are allowed to short, they can and will release their
215 Thus we recommend that you take some care when handling our batteries
216 and consider giving them some extra protection in your air-frame. We
217 often wrap them in suitable scraps of closed-cell packing foam before
218 strapping them down, for example.
221 The barometric sensors used on both TeleMetrum and TeleMini are
222 sensitive to sunlight. In normal TeleMetrum mounting situations, it
223 and all of the other surface mount components
224 are "down" towards whatever the underlying mounting surface is, so
225 this is not normally a problem. Please consider this, though, when
226 designing an installation, for example, in an air-frame with a
227 see-through plastic payload bay. It is particularly important to
228 consider this with TeleMini, both because the baro sensor is on the
229 "top" of the board, and because many model rockets with payload bays
230 use clear plastic for the payload bay! Replacing these with an opaque
231 cardboard tube, painting them, or wrapping them with a layer of masking
232 tape are all reasonable approaches to keep the sensor out of direct
236 The barometric sensor sampling port must be able to "breathe",
237 both by not being covered by foam or tape or other materials that might
238 directly block the hole on the top of the sensor, and also by having a
239 suitable static vent to outside air.
242 As with all other rocketry electronics, Altus Metrum altimeters must
243 be protected from exposure to corrosive motor exhaust and ejection
248 <title>Hardware Overview</title>
250 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
251 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
252 small in diameter may require some creativity in mounting and wiring
253 to succeed! The presence of an accelerometer means TeleMetrum should
254 be aligned along the flight axis of the airframe, and by default the 1/4
255 wave UHF wire antenna should be on the nose-cone end of the board. The
256 antenna wire is about 7 inches long, and wiring for a power switch and
257 the e-matches for apogee and main ejection charges depart from the
258 fin can end of the board, meaning an ideal "simple" avionics
259 bay for TeleMetrum should have at least 10 inches of interior length.
262 TeleMini is a 0.5 inch by 1.5 inch circuit board. It was designed to
263 fit inside an 18mm air-frame tube, but using it in a tube that
264 small in diameter may require some creativity in mounting and wiring
265 to succeed! Since there is no accelerometer, TeleMini can be mounted
266 in any convenient orientation. The default 1/4
267 wave UHF wire antenna attached to the center of one end of
268 the board is about 7 inches long, and wiring for a power switch and
269 the e-matches for apogee and main ejection charges depart from the
270 other end of the board, meaning an ideal "simple" avionics
271 bay for TeleMini should have at least 9 inches of interior length.
274 A typical TeleMetrum or TeleMini installation involves attaching
275 only a suitable Lithium Polymer battery, a single pole switch for
276 power on/off, and two pairs of wires connecting e-matches for the
277 apogee and main ejection charges. All Altus Metrum products are
278 designed for use with single-cell batteries with 3.7 volts nominal.
281 The battery connectors are a standard 2-pin JST connector and
282 match batteries sold by Spark Fun. These batteries are
283 single-cell Lithium Polymer batteries that nominally provide 3.7
284 volts. Other vendors sell similar batteries for RC aircraft
285 using mating connectors, however the polarity for those is
286 generally reversed from the batteries used by Altus Metrum
287 products. In particular, the Tenergy batteries supplied for use
288 in Featherweight flight computers are not compatible with Altus
289 Metrum flight computers or battery chargers. <emphasis>Check
290 polarity and voltage before connecting any battery not purchased
291 from Altus Metrum or Spark Fun.</emphasis>
294 By default, we use the unregulated output of the Li-Po battery directly
295 to fire ejection charges. This works marvelously with standard
296 low-current e-matches like the J-Tek from MJG Technologies, and with
297 Quest Q2G2 igniters. However, if you want or need to use a separate
298 pyro battery, check out the "External Pyro Battery" section in this
299 manual for instructions on how to wire that up. The altimeters are
300 designed to work with an external pyro battery of no more than 15 volts.
303 Ejection charges are wired directly to the screw terminal block
304 at the aft end of the altimeter. You'll need a very small straight
305 blade screwdriver for these screws, such as you might find in a
306 jeweler's screwdriver set.
309 TeleMetrum also uses the screw terminal block for the power
310 switch leads. On TeleMini, the power switch leads are soldered
311 directly to the board and can be connected directly to a switch.
314 For most air-frames, the integrated antennas are more than
315 adequate. However, if you are installing in a carbon-fiber or
316 metal electronics bay which is opaque to RF signals, you may need to
317 use off-board external antennas instead. In this case, you can
318 order an altimeter with an SMA connector for the UHF antenna
319 connection, and, on TeleMetrum, you can unplug the integrated GPS
320 antenna and select an appropriate off-board GPS antenna with
321 cable terminating in a U.FL connector.
325 <title>System Operation</title>
327 <title>Firmware Modes </title>
329 The AltOS firmware build for the altimeters has two
330 fundamental modes, "idle" and "flight". Which of these modes
331 the firmware operates in is determined at start up time. For
332 TeleMetrum, the mode is controlled by the orientation of the
333 rocket (well, actually the board, of course...) at the time
334 power is switched on. If the rocket is "nose up", then
335 TeleMetrum assumes it's on a rail or rod being prepared for
336 launch, so the firmware chooses flight mode. However, if the
337 rocket is more or less horizontal, the firmware instead enters
338 idle mode. Since TeleMini doesn't have an accelerometer we can
339 use to determine orientation, "idle" mode is selected when the
340 board receives a command packet within the first five seconds
341 of operation; if no packet is received, the board enters
345 At power on, you will hear three beeps or see three flashes
346 ("S" in Morse code for start up) and then a pause while
347 the altimeter completes initialization and self test, and decides
348 which mode to enter next.
351 In flight or "pad" mode, the altimeter engages the flight
352 state machine, goes into transmit-only mode to
353 send telemetry, and waits for launch to be detected.
354 Flight mode is indicated by an "di-dah-dah-dit" ("P" for pad)
355 on the beeper or lights, followed by beeps or flashes
356 indicating the state of the pyrotechnic igniter continuity.
357 One beep/flash indicates apogee continuity, two beeps/flashes
358 indicate main continuity, three beeps/flashes indicate both
359 apogee and main continuity, and one longer "brap" sound or
360 rapidly alternating lights indicates no continuity. For a
361 dual deploy flight, make sure you're getting three beeps or
362 flashes before launching! For apogee-only or motor eject
363 flights, do what makes sense.
366 If idle mode is entered, you will hear an audible "di-dit" or see
367 two short flashes ("I" for idle), and the flight state machine is
368 disengaged, thus no ejection charges will fire. The altimeters also
369 listen for the radio link when in idle mode for requests sent via
370 TeleDongle. Commands can be issued to a TeleMetrum in idle mode
372 USB or the radio link equivalently. TeleMini only has the radio link.
373 Idle mode is useful for configuring the altimeter, for extracting data
374 from the on-board storage chip after flight, and for ground testing
378 One "neat trick" of particular value when TeleMetrum is used with
379 very large air-frames, is that you can power the board up while the
380 rocket is horizontal, such that it comes up in idle mode. Then you can
381 raise the air-frame to launch position, and issue a 'reset' command
382 via TeleDongle over the radio link to cause the altimeter to reboot and
383 come up in flight mode. This is much safer than standing on the top
384 step of a rickety step-ladder or hanging off the side of a launch
385 tower with a screw-driver trying to turn on your avionics before
392 TeleMetrum includes a complete GPS receiver. A complete explanation
393 of how GPS works is beyond the scope of this manual, but the bottom
394 line is that the TeleMetrum GPS receiver needs to lock onto at least
395 four satellites to obtain a solid 3 dimensional position fix and know
399 TeleMetrum provides backup power to the GPS chip any time a
400 battery is connected. This allows the receiver to "warm start" on
401 the launch rail much faster than if every power-on were a GPS
402 "cold start". In typical operations, powering up TeleMetrum
403 on the flight line in idle mode while performing final air-frame
404 preparation will be sufficient to allow the GPS receiver to cold
405 start and acquire lock. Then the board can be powered down during
406 RSO review and installation on a launch rod or rail. When the board
407 is turned back on, the GPS system should lock very quickly, typically
408 long before igniter installation and return to the flight line are
413 <title>Controlling An Altimeter Over The Radio Link</title>
415 One of the unique features of the Altus Metrum system is
416 the ability to create a two way command link between TeleDongle
417 and an altimeter using the digital radio transceivers built into
418 each device. This allows you to interact with the altimeter from
419 afar, as if it were directly connected to the computer.
422 Any operation which can be performed with TeleMetrum can
423 either be done with TeleMetrum directly connected to the
424 computer via the USB cable, or through the radio
425 link. TeleMini doesn't provide a USB connector and so it is
426 always communicated with over radio. Select the appropriate
427 TeleDongle device when the list of devices is presented and
428 AltosUI will interact with an altimeter over the radio link.
431 One oddity in the current interface is how AltosUI selects the
432 frequency for radio communications. Instead of providing
433 an interface to specifically configure the frequency, it uses
434 whatever frequency was most recently selected for the target
435 TeleDongle device in Monitor Flight mode. If you haven't ever
436 used that mode with the TeleDongle in question, select the
437 Monitor Flight button from the top level UI, and pick the
438 appropriate TeleDongle device. Once the flight monitoring
439 window is open, select the desired frequency and then close it
440 down again. All radio communications will now use that frequency.
445 Save Flight Data—Recover flight data from the rocket without
451 Configure altimeter apogee delays or main deploy heights
452 to respond to changing launch conditions. You can also
453 'reboot' the altimeter. Use this to remotely enable the
454 flight computer by turning TeleMetrum on in "idle" mode,
455 then once the air-frame is oriented for launch, you can
456 reboot the altimeter and have it restart in pad mode
457 without having to climb the scary ladder.
462 Fire Igniters—Test your deployment charges without snaking
463 wires out through holes in the air-frame. Simply assembly the
464 rocket as if for flight with the apogee and main charges
465 loaded, then remotely command the altimeter to fire the
471 Operation over the radio link for configuring an altimeter, ground
472 testing igniters, and so forth uses the same RF frequencies as flight
473 telemetry. To configure the desired TeleDongle frequency, select
474 the monitor flight tab, then use the frequency selector and
475 close the window before performing other desired radio operations.
478 TeleMetrum only enables radio commanding in 'idle' mode, so
479 make sure you have TeleMetrum lying horizontally when you turn
480 it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
481 flight, and will not be listening for command packets from TeleDongle.
484 TeleMini listens for a command packet for five seconds after
485 first being turned on, if it doesn't hear anything, it enters
486 'pad' mode, ready for flight and will no longer listen for
487 command packets. The easiest way to connect to TeleMini is to
488 initiate the command and select the TeleDongle device. At this
489 point, the TeleDongle will be attempting to communicate with
490 the TeleMini. Now turn TeleMini on, and it should immediately
491 start communicating with the TeleDongle and the desired
492 operation can be performed.
495 You can monitor the operation of the radio link by watching the
496 lights on the devices. The red LED will flash each time a packet
497 is transmitted, while the green LED will light up on TeleDongle when
498 it is waiting to receive a packet from the altimeter.
502 <title>Ground Testing </title>
504 An important aspect of preparing a rocket using electronic deployment
505 for flight is ground testing the recovery system. Thanks
506 to the bi-directional radio link central to the Altus Metrum system,
507 this can be accomplished in a TeleMetrum or TeleMini equipped rocket
508 with less work than you may be accustomed to with other systems. It
512 Just prep the rocket for flight, then power up the altimeter
513 in "idle" mode (placing air-frame horizontal for TeleMetrum or
514 selected the Configure Altimeter tab for TeleMini). This will cause
515 the firmware to go into "idle" mode, in which the normal flight
516 state machine is disabled and charges will not fire without
517 manual command. You can now command the altimeter to fire the apogee
518 or main charges from a safe distance using your computer and
519 TeleDongle and the Fire Igniter tab to complete ejection testing.
523 <title>Radio Link </title>
525 The chip our boards are based on incorporates an RF transceiver, but
526 it's not a full duplex system... each end can only be transmitting or
527 receiving at any given moment. So we had to decide how to manage the
531 By design, the altimeter firmware listens for the radio link when
532 it's in "idle mode", which
533 allows us to use the radio link to configure the rocket, do things like
534 ejection tests, and extract data after a flight without having to
535 crack open the air-frame. However, when the board is in "flight
536 mode", the altimeter only
537 transmits and doesn't listen at all. That's because we want to put
538 ultimate priority on event detection and getting telemetry out of
540 the radio in case the rocket crashes and we aren't able to extract
544 We don't use a 'normal packet radio' mode like APRS because they're
545 just too inefficient. The GFSK modulation we use is FSK with the
546 base-band pulses passed through a
547 Gaussian filter before they go into the modulator to limit the
548 transmitted bandwidth. When combined with the hardware forward error
549 correction support in the cc1111 chip, this allows us to have a very
550 robust 38.4 kilobit data link with only 10 milliwatts of transmit
551 power, a whip antenna in the rocket, and a hand-held Yagi on the
552 ground. We've had flights to above 21k feet AGL with great reception,
553 and calculations suggest we should be good to well over 40k feet AGL
554 with a 5-element yagi on the ground. We hope to fly boards to higher
555 altitudes over time, and would of course appreciate customer feedback
556 on performance in higher altitude flights!
560 <title>Configurable Parameters</title>
562 Configuring an Altus Metrum altimeter for flight is very
563 simple. Even on our baro-only TeleMini board, the use of a Kalman
564 filter means there is no need to set a "mach delay". The few
565 configurable parameters can all be set using AltosUI over USB or
566 or radio link via TeleDongle.
569 <title>Radio Frequency</title>
571 Altus Metrum boards support radio frequencies in the 70cm
572 band. By default, the configuration interface provides a
573 list of 10 "standard" frequencies in 100kHz channels starting at
574 434.550MHz. However, the firmware supports use of
575 any 50kHz multiple within the 70cm band. At any given
576 launch, we highly recommend coordinating when and by whom each
577 frequency will be used to avoid interference. And of course, both
578 altimeter and TeleDongle must be configured to the same
579 frequency to successfully communicate with each other.
583 <title>Apogee Delay</title>
585 Apogee delay is the number of seconds after the altimeter detects flight
586 apogee that the drogue charge should be fired. In most cases, this
587 should be left at the default of 0. However, if you are flying
588 redundant electronics such as for an L3 certification, you may wish
589 to set one of your altimeters to a positive delay so that both
590 primary and backup pyrotechnic charges do not fire simultaneously.
593 The Altus Metrum apogee detection algorithm fires exactly at
594 apogee. If you are also flying an altimeter like the
595 PerfectFlite MAWD, which only supports selecting 0 or 1
596 seconds of apogee delay, you may wish to set the MAWD to 0
597 seconds delay and set the TeleMetrum to fire your backup 2
598 or 3 seconds later to avoid any chance of both charges
599 firing simultaneously. We've flown several air-frames this
600 way quite happily, including Keith's successful L3 cert.
604 <title>Main Deployment Altitude</title>
606 By default, the altimeter will fire the main deployment charge at an
607 elevation of 250 meters (about 820 feet) above ground. We think this
608 is a good elevation for most air-frames, but feel free to change this
609 to suit. In particular, if you are flying two altimeters, you may
611 deployment elevation for the backup altimeter to be something lower
612 than the primary so that both pyrotechnic charges don't fire
617 <title>Maximum Flight Log</title>
619 TeleMetrum version 1.1 and 1.2 have 2MB of on-board flash storage,
620 enough to hold over 40 minutes of data at full data rate
621 (100 samples/second). TeleMetrum 1.0 has 1MB of on-board
622 storage. As data are stored at a reduced rate during descent
623 (10 samples/second), there's plenty of space to store many
624 flights worth of data.
627 The on-board flash is partitioned into separate flight logs,
628 each of a fixed maximum size. Increase the maximum size of
629 each log and you reduce the number of flights that can be
630 stored. Decrease the size and TeleMetrum can store more
634 All of the configuration data is also stored in the flash
635 memory, which consumes 64kB on TeleMetrum v1.1/v1.2 and 256B on
636 TeleMetrum v1.0. This configuration space is not available
637 for storing flight log data.
640 To compute the amount of space needed for a single flight,
641 you can multiply the expected ascent time (in seconds) by
642 800, multiply the expected descent time (in seconds) by 80
643 and add the two together. That will slightly under-estimate
644 the storage (in bytes) needed for the flight. For instance,
645 a flight spending 20 seconds in ascent and 150 seconds in
646 descent will take about (20 * 800) + (150 * 80) = 28000
647 bytes of storage. You could store dozens of these flights in
651 The default size, 192kB, allows for 10 flights of storage on
652 TeleMetrum v1.1/v1.2 and 5 flights on TeleMetrum v1.0. This
653 ensures that you won't need to erase the memory before
654 flying each time while still allowing more than sufficient
655 storage for each flight.
658 As TeleMini does not contain an accelerometer, it stores
659 data at 10 samples per second during ascent and one sample
660 per second during descent. Each sample is a two byte reading
661 from the barometer. These are stored in 5kB of
662 on-chip flash memory which can hold 256 seconds at the
663 ascent rate or 2560 seconds at the descent rate. Because of
664 the limited storage, TeleMini cannot hold data for more than
665 one flight, and so must be erased after each flight or it
666 will not capture data for subsequent flights.
670 <title>Ignite Mode</title>
672 Instead of firing one charge at apogee and another charge at
673 a fixed height above the ground, you can configure the
674 altimeter to fire both at apogee or both during
675 descent. This was added to support an airframe that has two
676 TeleMetrum computers, one in the fin can and one in the
680 Providing the ability to use both igniters for apogee or
681 main allows some level of redundancy without needing two
682 flight computers. In Redundant Apogee or Redundant Main
683 mode, the two charges will be fired two seconds apart.
687 <title>Pad Orientation</title>
689 TeleMetrum measures acceleration along the axis of the
690 board. Which way the board is oriented affects the sign of
691 the acceleration value. Instead of trying to guess which way
692 the board is mounted in the air frame, TeleMetrum must be
693 explicitly configured for either Antenna Up or Antenna
694 Down. The default, Antenna Up, expects the end of the
695 TeleMetrum board connected to the 70cm antenna to be nearest
696 the nose of the rocket, with the end containing the screw
697 terminals nearest the tail.
705 <title>AltosUI</title>
707 The AltosUI program provides a graphical user interface for
708 interacting with the Altus Metrum product family, including
709 TeleMetrum, TeleMini and TeleDongle. AltosUI can monitor telemetry data,
710 configure TeleMetrum, TeleMini and TeleDongle devices and many other
711 tasks. The primary interface window provides a selection of
712 buttons, one for each major activity in the system. This manual
713 is split into chapters, each of which documents one of the tasks
714 provided from the top-level toolbar.
717 <title>Monitor Flight</title>
718 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
720 Selecting this item brings up a dialog box listing all of the
721 connected TeleDongle devices. When you choose one of these,
722 AltosUI will create a window to display telemetry data as
723 received by the selected TeleDongle device.
726 All telemetry data received are automatically recorded in
727 suitable log files. The name of the files includes the current
728 date and rocket serial and flight numbers.
731 The radio frequency being monitored by the TeleDongle device is
732 displayed at the top of the window. You can configure the
733 frequency by clicking on the frequency box and selecting the desired
734 frequency. AltosUI remembers the last frequency selected for each
735 TeleDongle and selects that automatically the next time you use
739 Below the TeleDongle frequency selector, the window contains a few
740 significant pieces of information about the altimeter providing
741 the telemetry data stream:
745 <para>The configured call-sign</para>
748 <para>The device serial number</para>
751 <para>The flight number. Each altimeter remembers how many
757 The rocket flight state. Each flight passes through several
758 states including Pad, Boost, Fast, Coast, Drogue, Main and
764 The Received Signal Strength Indicator value. This lets
765 you know how strong a signal TeleDongle is receiving. The
766 radio inside TeleDongle operates down to about -99dBm;
767 weaker signals may not be receivable. The packet link uses
768 error detection and correction techniques which prevent
769 incorrect data from being reported.
774 The age of the displayed data, in seconds since the last
775 successfully received telemetry packet. In normal operation
776 this will stay in the low single digits. If the number starts
777 counting up, then you are no longer receiving data over the radio
778 link from the flight computer.
783 Finally, the largest portion of the window contains a set of
784 tabs, each of which contain some information about the rocket.
785 They're arranged in 'flight order' so that as the flight
786 progresses, the selected tab automatically switches to display
787 data relevant to the current state of the flight. You can select
788 other tabs at any time. The final 'table' tab displays all of
789 the raw telemetry values in one place in a spreadsheet-like format.
792 <title>Launch Pad</title>
794 The 'Launch Pad' tab shows information used to decide when the
795 rocket is ready for flight. The first elements include red/green
796 indicators, if any of these is red, you'll want to evaluate
797 whether the rocket is ready to launch:
801 Battery Voltage. This indicates whether the Li-Po battery
802 powering the TeleMetrum has sufficient charge to last for
803 the duration of the flight. A value of more than
804 3.7V is required for a 'GO' status.
809 Apogee Igniter Voltage. This indicates whether the apogee
810 igniter has continuity. If the igniter has a low
811 resistance, then the voltage measured here will be close
812 to the Li-Po battery voltage. A value greater than 3.2V is
813 required for a 'GO' status.
818 Main Igniter Voltage. This indicates whether the main
819 igniter has continuity. If the igniter has a low
820 resistance, then the voltage measured here will be close
821 to the Li-Po battery voltage. A value greater than 3.2V is
822 required for a 'GO' status.
827 On-board Data Logging. This indicates whether there is
828 space remaining on-board to store flight data for the
829 upcoming flight. If you've downloaded data, but failed
830 to erase flights, there may not be any space
831 left. TeleMetrum can store multiple flights, depending
832 on the configured maximum flight log size. TeleMini
833 stores only a single flight, so it will need to be
834 downloaded and erased after each flight to capture
835 data. This only affects on-board flight logging; the
836 altimeter will still transmit telemetry and fire
837 ejection charges at the proper times.
842 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
843 currently able to compute position information. GPS requires
844 at least 4 satellites to compute an accurate position.
849 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
850 10 consecutive positions without losing lock. This ensures
851 that the GPS receiver has reliable reception from the
857 The Launchpad tab also shows the computed launch pad position
858 and altitude, averaging many reported positions to improve the
864 <title>Ascent</title>
866 This tab is shown during Boost, Fast and Coast
867 phases. The information displayed here helps monitor the
868 rocket as it heads towards apogee.
871 The height, speed and acceleration are shown along with the
872 maximum values for each of them. This allows you to quickly
873 answer the most commonly asked questions you'll hear during
877 The current latitude and longitude reported by the TeleMetrum GPS are
878 also shown. Note that under high acceleration, these values
879 may not get updated as the GPS receiver loses position
880 fix. Once the rocket starts coasting, the receiver should
881 start reporting position again.
884 Finally, the current igniter voltages are reported as in the
885 Launch Pad tab. This can help diagnose deployment failures
886 caused by wiring which comes loose under high acceleration.
890 <title>Descent</title>
892 Once the rocket has reached apogee and (we hope) activated the
893 apogee charge, attention switches to tracking the rocket on
894 the way back to the ground, and for dual-deploy flights,
895 waiting for the main charge to fire.
898 To monitor whether the apogee charge operated correctly, the
899 current descent rate is reported along with the current
900 height. Good descent rates vary based on the choice of recovery
901 components, but generally range from 15-30m/s on drogue and should
902 be below 10m/s when under the main parachute in a dual-deploy flight.
905 For TeleMetrum altimeters, you can locate the rocket in the
906 sky using the elevation and bearing information to figure
907 out where to look. Elevation is in degrees above the
908 horizon. Bearing is reported in degrees relative to true
909 north. Range can help figure out how big the rocket will
910 appear. Ground Distance shows how far it is to a point
911 directly under the rocket and can help figure out where the
912 rocket is likely to land. Note that all of these values are
913 relative to the pad location. If the elevation is near 90°,
914 the rocket is over the pad, not over you.
917 Finally, the igniter voltages are reported in this tab as
918 well, both to monitor the main charge as well as to see what
919 the status of the apogee charge is. Note that some commercial
920 e-matches are designed to retain continuity even after being
921 fired, and will continue to show as green or return from red to
926 <title>Landed</title>
928 Once the rocket is on the ground, attention switches to
929 recovery. While the radio signal is often lost once the
930 rocket is on the ground, the last reported GPS position is
931 generally within a short distance of the actual landing location.
934 The last reported GPS position is reported both by
935 latitude and longitude as well as a bearing and distance from
936 the launch pad. The distance should give you a good idea of
937 whether to walk or hitch a ride. Take the reported
938 latitude and longitude and enter them into your hand-held GPS
939 unit and have that compute a track to the landing location.
942 Both TeleMini and TeleMetrum will continue to transmit RDF
943 tones after landing, allowing you to locate the rocket by
944 following the radio signal if necessary. You may need to get
945 away from the clutter of the flight line, or even get up on
946 a hill (or your neighbor's RV roof) to receive the RDF signal.
949 The maximum height, speed and acceleration reported
950 during the flight are displayed for your admiring observers.
951 The accuracy of these immediate values depends on the quality
952 of your radio link and how many packets were received.
953 Recovering the on-board data after flight will likely yield
954 more precise results.
957 To get more detailed information about the flight, you can
958 click on the 'Graph Flight' button which will bring up a
959 graph window for the current flight.
963 <title>Site Map</title>
965 When the TeleMetrum has a GPS fix, the Site Map tab will map
966 the rocket's position to make it easier for you to locate the
967 rocket, both while it is in the air, and when it has landed. The
968 rocket's state is indicated by color: white for pad, red for
969 boost, pink for fast, yellow for coast, light blue for drogue,
970 dark blue for main, and black for landed.
973 The map's scale is approximately 3m (10ft) per pixel. The map
974 can be dragged using the left mouse button. The map will attempt
975 to keep the rocket roughly centered while data is being received.
978 Images are fetched automatically via the Google Maps Static API,
979 and cached on disk for reuse. If map images cannot be downloaded,
980 the rocket's path will be traced on a dark gray background
984 You can pre-load images for your favorite launch sites
985 before you leave home; check out the 'Preload Maps' section below.
990 <title>Save Flight Data</title>
992 The altimeter records flight data to its internal flash memory.
993 TeleMetrum data is recorded at a much higher rate than the telemetry
994 system can handle, and is not subject to radio drop-outs. As
995 such, it provides a more complete and precise record of the
996 flight. The 'Save Flight Data' button allows you to read the
997 flash memory and write it to disk. As TeleMini has only a barometer, it
998 records data at the same rate as the telemetry signal, but there will be
999 no data lost due to telemetry drop-outs.
1002 Clicking on the 'Save Flight Data' button brings up a list of
1003 connected TeleMetrum and TeleDongle devices. If you select a
1004 TeleMetrum device, the flight data will be downloaded from that
1005 device directly. If you select a TeleDongle device, flight data
1006 will be downloaded from an altimeter over radio link via the
1007 specified TeleDongle. See the chapter on Controlling An Altimeter
1008 Over The Radio Link for more information.
1011 After the device has been selected, a dialog showing the
1012 flight data saved in the device will be shown allowing you to
1013 select which flights to download and which to delete. With
1014 version 0.9 or newer firmware, you must erase flights in order
1015 for the space they consume to be reused by another
1016 flight. This prevents accidentally losing flight data
1017 if you neglect to download data before flying again. Note that
1018 if there is no more space available in the device, then no
1019 data will be recorded during the next flight.
1022 The file name for each flight log is computed automatically
1023 from the recorded flight date, altimeter serial number and
1024 flight number information.
1028 <title>Replay Flight</title>
1030 Select this button and you are prompted to select a flight
1031 record file, either a .telem file recording telemetry data or a
1032 .eeprom file containing flight data saved from the altimeter
1036 Once a flight record is selected, the flight monitor interface
1037 is displayed and the flight is re-enacted in real time. Check
1038 the Monitor Flight chapter above to learn how this window operates.
1042 <title>Graph Data</title>
1044 Select this button and you are prompted to select a flight
1045 record file, either a .telem file recording telemetry data or a
1046 .eeprom file containing flight data saved from
1050 Once a flight record is selected, a window with two tabs is
1051 opened. The first tab contains a graph with acceleration
1052 (blue), velocity (green) and altitude (red) of the flight,
1053 measured in metric units. The
1054 apogee(yellow) and main(magenta) igniter voltages are also
1055 displayed; high voltages indicate continuity, low voltages
1056 indicate open circuits. The second tab contains some basic
1060 The graph can be zoomed into a particular area by clicking and
1061 dragging down and to the right. Once zoomed, the graph can be
1062 reset by clicking and dragging up and to the left. Holding down
1063 control and clicking and dragging allows the graph to be panned.
1064 The right mouse button causes a pop-up menu to be displayed, giving
1065 you the option save or print the plot.
1068 Note that telemetry files will generally produce poor graphs
1069 due to the lower sampling rate and missed telemetry packets.
1070 Use saved flight data in .eeprom files for graphing where possible.
1074 <title>Export Data</title>
1076 This tool takes the raw data files and makes them available for
1077 external analysis. When you select this button, you are prompted to
1079 data file (either .eeprom or .telem will do, remember that
1080 .eeprom files contain higher resolution and more continuous
1081 data). Next, a second dialog appears which is used to select
1082 where to write the resulting file. It has a selector to choose
1083 between CSV and KML file formats.
1086 <title>Comma Separated Value Format</title>
1088 This is a text file containing the data in a form suitable for
1089 import into a spreadsheet or other external data analysis
1090 tool. The first few lines of the file contain the version and
1091 configuration information from the altimeter, then
1092 there is a single header line which labels all of the
1093 fields. All of these lines start with a '#' character which
1094 many tools can be configured to skip over.
1097 The remaining lines of the file contain the data, with each
1098 field separated by a comma and at least one space. All of
1099 the sensor values are converted to standard units, with the
1100 barometric data reported in both pressure, altitude and
1101 height above pad units.
1105 <title>Keyhole Markup Language (for Google Earth)</title>
1107 This is the format used by Google Earth to provide an overlay
1108 within that application. With this, you can use Google Earth to
1109 see the whole flight path in 3D.
1114 <title>Configure Altimeter</title>
1116 Select this button and then select either a TeleMetrum or
1117 TeleDongle Device from the list provided. Selecting a TeleDongle
1118 device will use the radio link to configure a remote altimeter.
1121 The first few lines of the dialog provide information about the
1122 connected device, including the product name,
1123 software version and hardware serial number. Below that are the
1124 individual configuration entries.
1127 At the bottom of the dialog, there are four buttons:
1132 Save. This writes any changes to the
1133 configuration parameter block in flash memory. If you don't
1134 press this button, any changes you make will be lost.
1139 Reset. This resets the dialog to the most recently saved values,
1140 erasing any changes you have made.
1145 Reboot. This reboots the device. Use this to
1146 switch from idle to pad mode by rebooting once the rocket is
1147 oriented for flight, or to confirm changes you think you saved
1153 Close. This closes the dialog. Any unsaved changes will be
1159 The rest of the dialog contains the parameters to be configured.
1162 <title>Main Deploy Altitude</title>
1164 This sets the altitude (above the recorded pad altitude) at
1165 which the 'main' igniter will fire. The drop-down menu shows
1166 some common values, but you can edit the text directly and
1167 choose whatever you like. If the apogee charge fires below
1168 this altitude, then the main charge will fire two seconds
1169 after the apogee charge fires.
1173 <title>Apogee Delay</title>
1175 When flying redundant electronics, it's often important to
1176 ensure that multiple apogee charges don't fire at precisely
1177 the same time, as that can over pressurize the apogee deployment
1178 bay and cause a structural failure of the air-frame. The Apogee
1179 Delay parameter tells the flight computer to fire the apogee
1180 charge a certain number of seconds after apogee has been
1185 <title>Radio Frequency</title>
1187 This configures which of the configured frequencies to use for both
1188 telemetry and packet command mode. Note that if you set this
1189 value via packet command mode, you will have to reconfigure
1190 the TeleDongle frequency before you will be able to use packet
1195 <title>Radio Calibration</title>
1197 The radios in every Altus Metrum device are calibrated at the
1198 factory to ensure that they transmit and receive on the
1199 specified frequency. If you need to you can adjust the calibration
1200 by changing this value. Do not do this without understanding what
1201 the value means, read the appendix on calibration and/or the source
1202 code for more information. To change a TeleDongle's calibration,
1203 you must reprogram the unit completely.
1207 <title>Callsign</title>
1209 This sets the call sign included in each telemetry packet. Set this
1210 as needed to conform to your local radio regulations.
1214 <title>Maximum Flight Log Size</title>
1216 This sets the space (in kilobytes) allocated for each flight
1217 log. The available space will be divided into chunks of this
1218 size. A smaller value will allow more flights to be stored,
1219 a larger value will record data from longer flights.
1223 <title>Ignite Mode</title>
1225 TeleMetrum and TeleMini provide two igniter channels as they
1226 were originally designed as dual-deploy flight
1227 computers. This configuration parameter allows the two
1228 channels to be used in different configurations.
1233 Dual Deploy. This is the usual mode of operation; the
1234 'apogee' channel is fired at apogee and the 'main'
1235 channel at the height above ground specified by the
1236 'Main Deploy Altitude' during descent.
1241 Redundant Apogee. This fires both channels at
1242 apogee, the 'apogee' channel first followed after a two second
1243 delay by the 'main' channel.
1248 Redundant Main. This fires both channels at the
1249 height above ground specified by the Main Deploy
1250 Altitude setting during descent. The 'apogee'
1251 channel is fired first, followed after a two second
1252 delay by the 'main' channel.
1258 <title>Pad Orientation</title>
1260 Because it includes an accelerometer, TeleMetrum is
1261 sensitive to the orientation of the board. By default, it
1262 expects the antenna end to point forward. This parameter
1263 allows that default to be changed, permitting the board to
1264 be mounted with the antenna pointing aft instead.
1269 Antenna Up. In this mode, the antenna end of the
1270 TeleMetrum board must point forward, in line with the
1271 expected flight path.
1276 Antenna Down. In this mode, the antenna end of the
1277 TeleMetrum board must point aft, in line with the
1278 expected flight path.
1285 <title>Configure AltosUI</title>
1287 This button presents a dialog so that you can configure the AltosUI global settings.
1290 <title>Voice Settings</title>
1292 AltosUI provides voice announcements during flight so that you
1293 can keep your eyes on the sky and still get information about
1294 the current flight status. However, sometimes you don't want
1299 <para>Enable—turns all voice announcements on and off</para>
1303 Test Voice—Plays a short message allowing you to verify
1304 that the audio system is working and the volume settings
1311 <title>Log Directory</title>
1313 AltosUI logs all telemetry data and saves all TeleMetrum flash
1314 data to this directory. This directory is also used as the
1315 staring point when selecting data files for display or export.
1318 Click on the directory name to bring up a directory choosing
1319 dialog, select a new directory and click 'Select Directory' to
1320 change where AltosUI reads and writes data files.
1324 <title>Callsign</title>
1326 This value is transmitted in each command packet sent from
1327 TeleDongle and received from an altimeter. It is not used in
1328 telemetry mode, as the callsign configured in the altimeter board
1329 is included in all telemetry packets. Configure this
1330 with the AltosUI operators call sign as needed to comply with
1331 your local radio regulations.
1335 <title>Imperial Units</title>
1337 This switches between metric units (meters) and imperial
1338 units (feet and miles). This affects the display of values
1339 use during flight monitoring, data graphing and all of the
1340 voice announcements. It does not change the units used when
1341 exporting to CSV files, those are always produced in metric units.
1345 <title>Font Size</title>
1347 Selects the set of fonts used in the flight monitor
1348 window. Choose between the small, medium and large sets.
1352 <title>Serial Debug</title>
1354 This causes all communication with a connected device to be
1355 dumped to the console from which AltosUI was started. If
1356 you've started it from an icon or menu entry, the output
1357 will simply be discarded. This mode can be useful to debug
1358 various serial communication issues.
1362 <title>Manage Frequencies</title>
1364 This brings up a dialog where you can configure the set of
1365 frequencies shown in the various frequency menus. You can
1366 add as many as you like, or even reconfigure the default
1367 set. Changing this list does not affect the frequency
1368 settings of any devices, it only changes the set of
1369 frequencies shown in the menus.
1374 <title>Configure Groundstation</title>
1376 Select this button and then select a TeleDongle Device from the list provided.
1379 The first few lines of the dialog provide information about the
1380 connected device, including the product name,
1381 software version and hardware serial number. Below that are the
1382 individual configuration entries.
1385 Note that the TeleDongle itself doesn't save any configuration
1386 data, the settings here are recorded on the local machine in
1387 the Java preferences database. Moving the TeleDongle to
1388 another machine, or using a different user account on the same
1389 machine will cause settings made here to have no effect.
1392 At the bottom of the dialog, there are three buttons:
1397 Save. This writes any changes to the
1398 local Java preferences file. If you don't
1399 press this button, any changes you make will be lost.
1404 Reset. This resets the dialog to the most recently saved values,
1405 erasing any changes you have made.
1410 Close. This closes the dialog. Any unsaved changes will be
1416 The rest of the dialog contains the parameters to be configured.
1419 <title>Frequency</title>
1421 This configures the frequency to use for both telemetry and
1422 packet command mode. Set this before starting any operation
1423 involving packet command mode so that it will use the right
1424 frequency. Telemetry monitoring mode also provides a menu to
1425 change the frequency, and that menu also sets the same Java
1426 preference value used here.
1430 <title>Radio Calibration</title>
1432 The radios in every Altus Metrum device are calibrated at the
1433 factory to ensure that they transmit and receive on the
1434 specified frequency. To change a TeleDongle's calibration,
1435 you must reprogram the unit completely, so this entry simply
1436 shows the current value and doesn't allow any changes.
1441 <title>Flash Image</title>
1443 This reprograms any Altus Metrum device by using a TeleMetrum
1444 or TeleDongle as a programming dongle. Please read the
1445 directions for flashing devices in the Updating Device
1446 Firmware chapter below.
1449 Once you have the programmer and target devices connected,
1450 push the 'Flash Image' button. That will present a dialog box
1451 listing all of the connected devices. Carefully select the
1452 programmer device, not the device to be programmed.
1455 Next, select the image to flash to the device. These are named
1456 with the product name and firmware version. The file selector
1457 will start in the directory containing the firmware included
1458 with the AltosUI package. Navigate to the directory containing
1459 the desired firmware if it isn't there.
1462 Next, a small dialog containing the device serial number and
1463 RF calibration values should appear. If these values are
1464 incorrect (possibly due to a corrupted image in the device),
1465 enter the correct values here.
1468 Finally, a dialog containing a progress bar will follow the
1469 programming process.
1472 When programming is complete, the target device will
1473 reboot. Note that if the target device is connected via USB, you
1474 will have to unplug it and then plug it back in for the USB
1475 connection to reset so that you can communicate with the device
1480 <title>Fire Igniter</title>
1482 This activates the igniter circuits in TeleMetrum to help test
1483 recovery systems deployment. Because this command can operate
1484 over the Packet Command Link, you can prepare the rocket as
1485 for flight and then test the recovery system without needing
1486 to snake wires inside the air-frame.
1489 Selecting the 'Fire Igniter' button brings up the usual device
1490 selection dialog. Pick the desired TeleDongle or TeleMetrum
1491 device. This brings up another window which shows the current
1492 continuity test status for both apogee and main charges.
1495 Next, select the desired igniter to fire. This will enable the
1499 Select the 'Arm' button. This enables the 'Fire' button. The
1500 word 'Arm' is replaced by a countdown timer indicating that
1501 you have 10 seconds to press the 'Fire' button or the system
1502 will deactivate, at which point you start over again at
1503 selecting the desired igniter.
1507 <title>Scan Channels</title>
1509 This listens for telemetry packets on all of the configured
1510 frequencies, displaying information about each device it
1511 receives a packet from. You can select which of the three
1512 telemetry formats should be tried; by default, it only listens
1513 for the standard telemetry packets used in v1.0 and later
1518 <title>Load Maps</title>
1520 Before heading out to a new launch site, you can use this to
1521 load satellite images in case you don't have internet
1522 connectivity at the site. This loads a fairly large area
1523 around the launch site, which should cover any flight you're likely to make.
1526 There's a drop-down menu of launch sites we know about; if
1527 your favorites aren't there, please let us know the lat/lon
1528 and name of the site. The contents of this list are actually
1529 downloaded at run-time, so as new sites are sent in, they'll
1530 get automatically added to this list.
1533 If the launch site isn't in the list, you can manually enter the lat/lon values
1536 Clicking the 'Load Map' button will fetch images from Google
1537 Maps; note that Google limits how many images you can fetch at
1538 once, so if you load more than one launch site, you may get
1539 some gray areas in the map which indicate that Google is tired
1540 of sending data to you. Try again later.
1544 <title>Monitor Idle</title>
1546 This brings up a dialog similar to the Monitor Flight UI,
1547 except it works with the altimeter in "idle" mode by sending
1548 query commands to discover the current state rather than
1549 listening for telemetry packets.
1554 <title>Using Altus Metrum Products</title>
1556 <title>Being Legal</title>
1558 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
1559 other authorization to legally operate the radio transmitters that are part
1564 <title>In the Rocket</title>
1566 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
1567 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
1568 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
1569 850mAh battery weighs less than a 9V alkaline battery, and will
1570 run a TeleMetrum for hours.
1571 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
1572 a few hours, or a TeleMini for much (much) longer.
1575 By default, we ship the altimeters with a simple wire antenna. If your
1576 electronics bay or the air-frame it resides within is made of carbon fiber,
1577 which is opaque to RF signals, you may choose to have an SMA connector
1578 installed so that you can run a coaxial cable to an antenna mounted
1579 elsewhere in the rocket.
1583 <title>On the Ground</title>
1585 To receive the data stream from the rocket, you need an antenna and short
1586 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. The
1587 TeleDongle in turn plugs directly into the USB port on a notebook
1588 computer. Because TeleDongle looks like a simple serial port, your computer
1589 does not require special device drivers... just plug it in.
1592 The GUI tool, AltosUI, is written in Java and runs across
1593 Linux, Mac OS and Windows. There's also a suite of C tools
1594 for Linux which can perform most of the same tasks.
1597 After the flight, you can use the radio link to extract the more detailed data
1598 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
1599 TeleMetrum board directly. Pulling out the data without having to open up
1600 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
1601 battery, so you'll want one of those anyway... the same cable used by lots
1602 of digital cameras and other modern electronic stuff will work fine.
1605 If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
1606 receiver, so that you can put in a way-point for the last reported rocket
1607 position before touch-down. This makes looking for your rocket a lot like
1608 Geo-Caching... just go to the way-point and look around starting from there.
1611 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
1612 can use that with your antenna to direction-find the rocket on the ground
1613 the same way you can use a Walston or Beeline tracker. This can be handy
1614 if the rocket is hiding in sage brush or a tree, or if the last GPS position
1615 doesn't get you close enough because the rocket dropped into a canyon, or
1616 the wind is blowing it across a dry lake bed, or something like that... Keith
1617 and Bdale both currently own and use the Yaesu VX-7R at launches.
1620 So, to recap, on the ground the hardware you'll need includes:
1621 <orderedlist inheritnum='inherit' numeration='arabic'>
1623 an antenna and feed-line
1632 optionally, a hand-held GPS receiver
1635 optionally, an HT or receiver covering 435 MHz
1640 The best hand-held commercial directional antennas we've found for radio
1641 direction finding rockets are from
1642 <ulink url="http://www.arrowantennas.com/" >
1645 The 440-3 and 440-5 are both good choices for finding a
1646 TeleMetrum- or TeleMini- equipped rocket when used with a suitable 70cm HT.
1650 <title>Data Analysis</title>
1652 Our software makes it easy to log the data from each flight, both the
1653 telemetry received during the flight itself, and the more
1654 complete data log recorded in the flash memory on the altimeter
1655 board. Once this data is on your computer, our post-flight tools make it
1656 easy to quickly get to the numbers everyone wants, like apogee altitude,
1657 max acceleration, and max velocity. You can also generate and view a
1658 standard set of plots showing the altitude, acceleration, and
1659 velocity of the rocket during flight. And you can even export a TeleMetrum data file
1660 usable with Google Maps and Google Earth for visualizing the flight path
1661 in two or three dimensions!
1664 Our ultimate goal is to emit a set of files for each flight that can be
1665 published as a web page per flight, or just viewed on your local disk with
1670 <title>Future Plans</title>
1672 In the future, we intend to offer "companion boards" for the rocket that will
1673 plug in to TeleMetrum to collect additional data, provide more pyro channels,
1677 We are also working on the design of a hand-held ground terminal that will
1678 allow monitoring the rocket's status, collecting data during flight, and
1679 logging data after flight without the need for a notebook computer on the
1680 flight line. Particularly since it is so difficult to read most notebook
1681 screens in direct sunlight, we think this will be a great thing to have.
1684 Because all of our work is open, both the hardware designs and the software,
1685 if you have some great idea for an addition to the current Altus Metrum family,
1686 feel free to dive in and help! Or let us know what you'd like to see that
1687 we aren't already working on, and maybe we'll get excited about it too...
1692 <title>Altimeter Installation Recommendations</title>
1694 Building high-power rockets that fly safely is hard enough. Mix
1695 in some sophisticated electronics and a bunch of radio energy
1696 and oftentimes you find few perfect solutions. This chapter
1697 contains some suggestions about how to install Altus Metrum
1698 products into the rocket air-frame, including how to safely and
1699 reliably mix a variety of electronics into the same air-frame.
1702 <title>Mounting the Altimeter</title>
1704 The first consideration is to ensure that the altimeter is
1705 securely fastened to the air-frame. For TeleMetrum, we use
1706 nylon standoffs and nylon screws; they're good to at least 50G
1707 and cannot cause any electrical issues on the board. For
1708 TeleMini, we usually cut small pieces of 1/16" balsa to fit
1709 under the screw holes, and then take 2x56 nylon screws and
1710 screw them through the TeleMini mounting holes, through the
1711 balsa and into the underlying material.
1713 <orderedlist inheritnum='inherit' numeration='arabic'>
1715 Make sure TeleMetrum is aligned precisely along the axis of
1716 acceleration so that the accelerometer can accurately
1717 capture data during the flight.
1720 Watch for any metal touching components on the
1721 board. Shorting out connections on the bottom of the board
1722 can cause the altimeter to fail during flight.
1727 <title>Dealing with the Antenna</title>
1729 The antenna supplied is just a piece of solid, insulated,
1730 wire. If it gets damaged or broken, it can be easily
1731 replaced. It should be kept straight and not cut; bending or
1732 cutting it will change the resonant frequency and/or
1733 impedance, making it a less efficient radiator and thus
1734 reducing the range of the telemetry signal.
1737 Keeping metal away from the antenna will provide better range
1738 and a more even radiation pattern. In most rockets, it's not
1739 entirely possible to isolate the antenna from metal
1740 components; there are often bolts, all-thread and wires from other
1741 electronics to contend with. Just be aware that the more stuff
1742 like this around the antenna, the lower the range.
1745 Make sure the antenna is not inside a tube made or covered
1746 with conducting material. Carbon fiber is the most common
1747 culprit here -- CF is a good conductor and will effectively
1748 shield the antenna, dramatically reducing signal strength and
1749 range. Metallic flake paint is another effective shielding
1750 material which is to be avoided around any antennas.
1753 If the ebay is large enough, it can be convenient to simply
1754 mount the altimeter at one end and stretch the antenna out
1755 inside. Taping the antenna to the sled can keep it straight
1756 under acceleration. If there are metal rods, keep the
1757 antenna as far away as possible.
1760 For a shorter ebay, it's quite practical to have the antenna
1761 run through a bulkhead and into an adjacent bay. Drill a small
1762 hole in the bulkhead, pass the antenna wire through it and
1763 then seal it up with glue or clay. We've also used acrylic
1764 tubing to create a cavity for the antenna wire. This works a
1765 bit better in that the antenna is known to stay straight and
1766 not get folded by recovery components in the bay. Angle the
1767 tubing towards the side wall of the rocket and it ends up
1768 consuming very little space.
1771 If you need to place the antenna at a distance from the
1772 altimeter, you can replace the antenna with an edge-mounted
1773 SMA connector, and then run 50Ω coax from the board to the
1774 antenna. Building a remote antenna is beyond the scope of this
1779 <title>Preserving GPS Reception</title>
1781 The GPS antenna and receiver in TeleMetrum are highly
1782 sensitive and normally have no trouble tracking enough
1783 satellites to provide accurate position information for
1784 recovering the rocket. However, there are many ways to
1785 attenuate the GPS signal.
1786 <orderedlist inheritnum='inherit' numeration='arabic'>
1788 Conductive tubing or coatings. Carbon fiber and metal
1789 tubing, or metallic paint will all dramatically attenuate the
1790 GPS signal. We've never heard of anyone successfully
1791 receiving GPS from inside these materials.
1794 Metal components near the GPS patch antenna. These will
1795 de-tune the patch antenna, changing the resonant frequency
1796 away from the L1 carrier and reduce the effectiveness of the
1797 antenna. You can place as much stuff as you like beneath the
1798 antenna as that's covered with a ground plane. But, keep
1799 wires and metal out from above the patch antenna.
1805 <title>Radio Frequency Interference</title>
1807 Any altimeter will generate RFI; the digital circuits use
1808 high-frequency clocks that spray radio interference across a
1809 wide band. Altus Metrum altimeters generate intentional radio
1810 signals as well, increasing the amount of RF energy around the board.
1813 Rocketry altimeters also use precise sensors measuring air
1814 pressure and acceleration. Tiny changes in voltage can cause
1815 these sensor readings to vary by a huge amount. When the
1816 sensors start mis-reporting data, the altimeter can either
1817 fire the igniters at the wrong time, or not fire them at all.
1820 Voltages are induced when radio frequency energy is
1821 transmitted from one circuit to another. Here are things that
1822 influence the induced voltage and current:
1826 Keep wires from different circuits apart. Moving circuits
1827 further apart will reduce RFI.
1830 Avoid parallel wires from different circuits. The longer two
1831 wires run parallel to one another, the larger the amount of
1832 transferred energy. Cross wires at right angles to reduce
1836 Twist wires from the same circuits. Two wires the same
1837 distance from the transmitter will get the same amount of
1838 induced energy which will then cancel out. Any time you have
1839 a wire pair running together, twist the pair together to
1840 even out distances and reduce RFI. For altimeters, this
1841 includes battery leads, switch hookups and igniter
1845 Avoid resonant lengths. Know what frequencies are present
1846 in the environment and avoid having wire lengths near a
1847 natural resonant length. Altusmetrum products transmit on the
1848 70cm amateur band, so you should avoid lengths that are a
1849 simple ratio of that length; essentially any multiple of 1/4
1850 of the wavelength (17.5cm).
1855 <title>The Barometric Sensor</title>
1857 Altusmetrum altimeters measure altitude with a barometric
1858 sensor, essentially measuring the amount of air above the
1859 rocket to figure out how high it is. A large number of
1860 measurements are taken as the altimeter initializes itself to
1861 figure out the pad altitude. Subsequent measurements are then
1862 used to compute the height above the pad.
1865 To accurately measure atmospheric pressure, the ebay
1866 containing the altimeter must be vented outside the
1867 air-frame. The vent must be placed in a region of linear
1868 airflow, have smooth edges, and away from areas of increasing or
1869 decreasing pressure.
1872 The barometric sensor in the altimeter is quite sensitive to
1873 chemical damage from the products of APCP or BP combustion, so
1874 make sure the ebay is carefully sealed from any compartment
1875 which contains ejection charges or motors.
1879 <title>Ground Testing</title>
1881 The most important aspect of any installation is careful
1882 ground testing. Bringing an air-frame up to the LCO table which
1883 hasn't been ground tested can lead to delays or ejection
1884 charges firing on the pad, or, even worse, a recovery system
1888 Do a 'full systems' test that includes wiring up all igniters
1889 without any BP and turning on all of the electronics in flight
1890 mode. This will catch any mistakes in wiring and any residual
1891 RFI issues that might accidentally fire igniters at the wrong
1892 time. Let the air-frame sit for several minutes, checking for
1893 adequate telemetry signal strength and GPS lock. If any igniters
1894 fire unexpectedly, find and resolve the issue before loading any
1898 Ground test the ejection charges. Prepare the rocket for
1899 flight, loading ejection charges and igniters. Completely
1900 assemble the air-frame and then use the 'Fire Igniters'
1901 interface through a TeleDongle to command each charge to
1902 fire. Make sure the charge is sufficient to robustly separate
1903 the air-frame and deploy the recovery system.
1908 <title>Updating Device Firmware</title>
1910 The big concept to understand is that you have to use a
1911 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
1912 and a TeleMetrum or other TeleDongle to program the TeleDongle
1913 Due to limited memory resources in the cc1111, we don't support
1914 programming directly over USB.
1917 You may wish to begin by ensuring you have current firmware images.
1918 These are distributed as part of the AltOS software bundle that
1919 also includes the AltosUI ground station program. Newer ground
1920 station versions typically work fine with older firmware versions,
1921 so you don't need to update your devices just to try out new
1922 software features. You can always download the most recent
1923 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
1926 We recommend updating the altimeter first, before updating TeleDongle.
1929 <title>Updating TeleMetrum Firmware</title>
1930 <orderedlist inheritnum='inherit' numeration='arabic'>
1932 Find the 'programming cable' that you got as part of the starter
1933 kit, that has a red 8-pin MicroMaTch connector on one end and a
1934 red 4-pin MicroMaTch connector on the other end.
1937 Take the 2 screws out of the TeleDongle case to get access
1938 to the circuit board.
1941 Plug the 8-pin end of the programming cable to the
1942 matching connector on the TeleDongle, and the 4-pin end to the
1943 matching connector on the TeleMetrum.
1944 Note that each MicroMaTch connector has an alignment pin that
1945 goes through a hole in the PC board when you have the cable
1949 Attach a battery to the TeleMetrum board.
1952 Plug the TeleDongle into your computer's USB port, and power
1956 Run AltosUI, and select 'Flash Image' from the File menu.
1959 Pick the TeleDongle device from the list, identifying it as the
1963 Select the image you want put on the TeleMetrum, which should have a
1964 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
1965 in the default directory, if not you may have to poke around
1966 your system to find it.
1969 Make sure the configuration parameters are reasonable
1970 looking. If the serial number and/or RF configuration
1971 values aren't right, you'll need to change them.
1974 Hit the 'OK' button and the software should proceed to flash
1975 the TeleMetrum with new firmware, showing a progress bar.
1978 Confirm that the TeleMetrum board seems to have updated OK, which you
1979 can do by plugging in to it over USB and using a terminal program
1980 to connect to the board and issue the 'v' command to check
1984 If something goes wrong, give it another try.
1989 <title>Updating TeleMini Firmware</title>
1990 <orderedlist inheritnum='inherit' numeration='arabic'>
1992 You'll need a special 'programming cable' to reprogram the
1993 TeleMini. It's available on the Altus Metrum web store, or
1994 you can make your own using an 8-pin MicroMaTch connector on
1995 one end and a set of four pins on the other.
1998 Take the 2 screws out of the TeleDongle case to get access
1999 to the circuit board.
2002 Plug the 8-pin end of the programming cable to the matching
2003 connector on the TeleDongle, and the 4-pins into the holes
2004 in the TeleMini circuit board. Note that the MicroMaTch
2005 connector has an alignment pin that goes through a hole in
2006 the PC board when you have the cable oriented correctly, and
2007 that pin 1 on the TeleMini board is marked with a square pad
2008 while the other pins have round pads.
2011 Attach a battery to the TeleMini board.
2014 Plug the TeleDongle into your computer's USB port, and power
2018 Run AltosUI, and select 'Flash Image' from the File menu.
2021 Pick the TeleDongle device from the list, identifying it as the
2025 Select the image you want put on the TeleMini, which should have a
2026 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
2027 in the default directory, if not you may have to poke around
2028 your system to find it.
2031 Make sure the configuration parameters are reasonable
2032 looking. If the serial number and/or RF configuration
2033 values aren't right, you'll need to change them.
2036 Hit the 'OK' button and the software should proceed to flash
2037 the TeleMini with new firmware, showing a progress bar.
2040 Confirm that the TeleMini board seems to have updated OK, which you
2041 can do by configuring it over the radio link through the TeleDongle, or
2042 letting it come up in "flight" mode and listening for telemetry.
2045 If something goes wrong, give it another try.
2050 <title>Updating TeleDongle Firmware</title>
2052 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
2053 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
2055 <orderedlist inheritnum='inherit' numeration='arabic'>
2057 Find the 'programming cable' that you got as part of the starter
2058 kit, that has a red 8-pin MicroMaTch connector on one end and a
2059 red 4-pin MicroMaTch connector on the other end.
2062 Find the USB cable that you got as part of the starter kit, and
2063 plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
2066 Take the 2 screws out of the TeleDongle case to get access
2067 to the circuit board.
2070 Plug the 8-pin end of the programming cable to the
2071 matching connector on the programmer, and the 4-pin end to the
2072 matching connector on the TeleDongle.
2073 Note that each MicroMaTch connector has an alignment pin that
2074 goes through a hole in the PC board when you have the cable
2078 Attach a battery to the TeleMetrum board if you're using one.
2081 Plug both the programmer and the TeleDongle into your computer's USB
2082 ports, and power up the programmer.
2085 Run AltosUI, and select 'Flash Image' from the File menu.
2088 Pick the programmer device from the list, identifying it as the
2092 Select the image you want put on the TeleDongle, which should have a
2093 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
2094 in the default directory, if not you may have to poke around
2095 your system to find it.
2098 Make sure the configuration parameters are reasonable
2099 looking. If the serial number and/or RF configuration
2100 values aren't right, you'll need to change them. The TeleDongle
2101 serial number is on the "bottom" of the circuit board, and can
2102 usually be read through the translucent blue plastic case without
2103 needing to remove the board from the case.
2106 Hit the 'OK' button and the software should proceed to flash
2107 the TeleDongle with new firmware, showing a progress bar.
2110 Confirm that the TeleDongle board seems to have updated OK, which you
2111 can do by plugging in to it over USB and using a terminal program
2112 to connect to the board and issue the 'v' command to check
2113 the version, etc. Once you're happy, remove the programming cable
2114 and put the cover back on the TeleDongle.
2117 If something goes wrong, give it another try.
2121 Be careful removing the programming cable from the locking 8-pin
2122 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
2123 screwdriver or knife blade to gently pry the locking ears out
2124 slightly to extract the connector. We used a locking connector on
2125 TeleMetrum to help ensure that the cabling to companion boards
2126 used in a rocket don't ever come loose accidentally in flight.
2131 <title>Hardware Specifications</title>
2133 <title>TeleMetrum Specifications</title>
2137 Recording altimeter for model rocketry.
2142 Supports dual deployment (can fire 2 ejection charges).
2147 70cm ham-band transceiver for telemetry down-link.
2152 Barometric pressure sensor good to 45k feet MSL.
2157 1-axis high-g accelerometer for motor characterization, capable of
2158 +/- 50g using default part.
2163 On-board, integrated GPS receiver with 5Hz update rate capability.
2168 On-board 1 megabyte non-volatile memory for flight data storage.
2173 USB interface for battery charging, configuration, and data recovery.
2178 Fully integrated support for Li-Po rechargeable batteries.
2183 Uses Li-Po to fire e-matches, can be modified to support
2184 optional separate pyro battery if needed.
2189 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
2195 <title>TeleMini Specifications</title>
2199 Recording altimeter for model rocketry.
2204 Supports dual deployment (can fire 2 ejection charges).
2209 70cm ham-band transceiver for telemetry down-link.
2214 Barometric pressure sensor good to 45k feet MSL.
2219 On-board 5 kilobyte non-volatile memory for flight data storage.
2224 RF interface for configuration, and data recovery.
2229 Support for Li-Po rechargeable batteries, using an external charger.
2234 Uses Li-Po to fire e-matches, can be modified to support
2235 optional separate pyro battery if needed.
2240 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
2249 TeleMetrum seems to shut off when disconnected from the
2250 computer. Make sure the battery is adequately charged. Remember the
2251 unit will pull more power than the USB port can deliver before the
2252 GPS enters "locked" mode. The battery charges best when TeleMetrum
2256 It's impossible to stop the TeleDongle when it's in "p" mode, I have
2257 to unplug the USB cable? Make sure you have tried to "escape out" of
2258 this mode. If this doesn't work the reboot procedure for the
2259 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
2260 outgoing buffer IF your "escape out" ('~~') does not work.
2261 At this point using either 'ao-view' (or possibly
2262 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
2266 The amber LED (on the TeleMetrum) lights up when both
2267 battery and USB are connected. Does this mean it's charging?
2268 Yes, the yellow LED indicates the charging at the 'regular' rate.
2269 If the led is out but the unit is still plugged into a USB port,
2270 then the battery is being charged at a 'trickle' rate.
2273 There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
2274 That's the "pad" mode. Weak batteries might be the problem.
2275 It is also possible that the TeleMetrum is horizontal and the output
2276 is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
2277 it received a command packet which would have left it in "pad" mode.
2280 How do I save flight data?
2281 Live telemetry is written to file(s) whenever AltosUI is connected
2282 to the TeleDongle. The file area defaults to ~/TeleMetrum
2283 but is easily changed using the menus in AltosUI. The files that
2284 are written end in '.telem'. The after-flight
2285 data-dumped files will end in .eeprom and represent continuous data
2286 unlike the .telem files that are subject to losses
2287 along the RF data path.
2288 See the above instructions on what and how to save the eeprom stored
2289 data after physically retrieving your altimeter. Make sure to save
2290 the on-board data after each flight; while the TeleMetrum can store
2291 multiple flights, you never know when you'll lose the altimeter...
2295 <title>Notes for Older Software</title>
2298 Before AltosUI was written, using Altus Metrum devices required
2299 some finesse with the Linux command line. There was a limited
2300 GUI tool, ao-view, which provided functionality similar to the
2301 Monitor Flight window in AltosUI, but everything else was a
2302 fairly 80's experience. This appendix includes documentation for
2303 using that software.
2307 Both TeleMetrum and TeleDongle can be directly communicated
2308 with using USB ports. The first thing you should try after getting
2309 both units plugged into to your computer's USB port(s) is to run
2310 'ao-list' from a terminal-window to see what port-device-name each
2311 device has been assigned by the operating system.
2312 You will need this information to access the devices via their
2313 respective on-board firmware and data using other command line
2314 programs in the AltOS software suite.
2317 TeleMini can be communicated with through a TeleDongle device
2318 over the radio link. When first booted, TeleMini listens for a
2319 TeleDongle device and if it receives a packet, it goes into
2320 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
2321 launched. The easiest way to get it talking is to start the
2322 communication link on the TeleDongle and the power up the
2326 To access the device's firmware for configuration you need a terminal
2327 program such as you would use to talk to a modem. The software
2328 authors prefer using the program 'cu' which comes from the UUCP package
2329 on most Unix-like systems such as Linux. An example command line for
2330 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
2331 indicated from running the
2332 ao-list program. Another reasonable terminal program for Linux is
2333 'cutecom'. The default 'escape'
2334 character used by CU (i.e. the character you use to
2335 issue commands to cu itself instead of sending the command as input
2336 to the connected device) is a '~'. You will need this for use in
2337 only two different ways during normal operations. First is to exit
2338 the program by sending a '~.' which is called a 'escape-disconnect'
2339 and allows you to close-out from 'cu'. The
2340 second use will be outlined later.
2343 All of the Altus Metrum devices share the concept of a two level
2344 command set in their firmware.
2345 The first layer has several single letter commands. Once
2346 you are using 'cu' (or 'cutecom') sending (typing) a '?'
2347 returns a full list of these
2348 commands. The second level are configuration sub-commands accessed
2349 using the 'c' command, for
2350 instance typing 'c?' will give you this second level of commands
2351 (all of which require the
2352 letter 'c' to access). Please note that most configuration options
2353 are stored only in Flash memory; TeleDongle doesn't provide any storage
2354 for these options and so they'll all be lost when you unplug it.
2357 Try setting these configuration ('c' or second level menu) values. A good
2358 place to start is by setting your call sign. By default, the boards
2359 use 'N0CALL' which is cute, but not exactly legal!
2360 Spend a few minutes getting comfortable with the units, their
2361 firmware, and 'cu' (or possibly 'cutecom').
2362 For instance, try to send
2363 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
2364 Verify you can connect and disconnect from the units while in your
2365 terminal program by sending the escape-disconnect mentioned above.
2368 To set the radio frequency, use the 'c R' command to specify the
2369 radio transceiver configuration parameter. This parameter is computed
2370 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
2371 the standard calibration reference frequency, 'S', (normally 434.550MHz):
2375 Round the result to the nearest integer value.
2376 As with all 'c' sub-commands, follow this with a 'c w' to write the
2377 change to the parameter block in the on-board flash on
2378 your altimeter board if you want the change to stay in place across reboots.
2381 To set the apogee delay, use the 'c d' command.
2382 As with all 'c' sub-commands, follow this with a 'c w' to write the
2383 change to the parameter block in the on-board DataFlash chip.
2386 To set the main deployment altitude, use the 'c m' command.
2387 As with all 'c' sub-commands, follow this with a 'c w' to write the
2388 change to the parameter block in the on-board DataFlash chip.
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 to generate a CW carrier. Wait for the transmitter temperature
2394 to stabilize and the frequency to settle down.
2395 Then, divide 434.550 MHz by the
2396 measured frequency and multiply by the current radio cal value show
2397 in the 'c s' command. For an unprogrammed board, the default value
2398 is 1186611. Take the resulting integer and program it using the 'c f'
2399 command. Testing with the 'C' command again should show a carrier
2400 within a few tens of Hertz of the intended frequency.
2401 As with all 'c' sub-commands, follow this with a 'c w' to write the
2402 change to the parameter block in the on-board DataFlash chip.
2405 Note that the 'reboot' command, which is very useful on the altimeters,
2406 will likely just cause problems with the dongle. The *correct* way
2407 to reset the dongle is just to unplug and re-plug it.
2410 A fun thing to do at the launch site and something you can do while
2411 learning how to use these units is to play with the radio link access
2412 between an altimeter and the TeleDongle. Be aware that you *must* create
2413 some physical separation between the devices, otherwise the link will
2414 not function due to signal overload in the receivers in each device.
2417 Now might be a good time to take a break and read the rest of this
2418 manual, particularly about the two "modes" that the altimeters
2419 can be placed in. TeleMetrum uses the position of the device when booting
2420 up will determine whether the unit is in "pad" or "idle" mode. TeleMini
2421 enters "idle" mode when it receives a command packet within the first 5 seconds
2422 of being powered up, otherwise it enters "pad" mode.
2425 You can access an altimeter in idle mode from the TeleDongle's USB
2426 connection using the radio link
2427 by issuing a 'p' command to the TeleDongle. Practice connecting and
2428 disconnecting ('~~' while using 'cu') from the altimeter. If
2429 you cannot escape out of the "p" command, (by using a '~~' when in
2430 CU) then it is likely that your kernel has issues. Try a newer version.
2433 Using this radio link allows you to configure the altimeter, test
2434 fire e-matches and igniters from the flight line, check pyro-match
2435 continuity and so forth. You can leave the unit turned on while it
2436 is in 'idle mode' and then place the
2437 rocket vertically on the launch pad, walk away and then issue a
2438 reboot command. The altimeter will reboot and start sending data
2439 having changed to the "pad" mode. If the TeleDongle is not receiving
2440 this data, you can disconnect 'cu' from the TeleDongle using the
2441 procedures mentioned above and THEN connect to the TeleDongle from
2442 inside 'ao-view'. If this doesn't work, disconnect from the
2443 TeleDongle, unplug it, and try again after plugging it back in.
2446 In order to reduce the chance of accidental firing of pyrotechnic
2447 charges, the command to fire a charge is intentionally somewhat
2448 difficult to type, and the built-in help is slightly cryptic to
2449 prevent accidental echoing of characters from the help text back at
2450 the board from firing a charge. The command to fire the apogee
2451 drogue charge is 'i DoIt drogue' and the command to fire the main
2452 charge is 'i DoIt main'.
2455 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
2456 and 'ao-view' will both auditorily announce and visually indicate
2458 Now you can launch knowing that you have a good data path and
2459 good satellite lock for flight data and recovery. Remember
2460 you MUST tell ao-view to connect to the TeleDongle explicitly in
2461 order for ao-view to be able to receive data.
2464 The altimeters provide RDF (radio direction finding) tones on
2465 the pad, during descent and after landing. These can be used to
2466 locate the rocket using a directional antenna; the signal
2467 strength providing an indication of the direction from receiver to rocket.
2470 TeleMetrum also provides GPS tracking data, which can further simplify
2471 locating the rocket once it has landed. (The last good GPS data
2472 received before touch-down will be on the data screen of 'ao-view'.)
2475 Once you have recovered the rocket you can download the eeprom
2476 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
2477 either a USB cable or over the radio link using TeleDongle.
2478 And by following the man page for 'ao-postflight' you can create
2479 various data output reports, graphs, and even KML data to see the
2480 flight trajectory in Google-earth. (Moving the viewing angle making
2481 sure to connect the yellow lines while in Google-earth is the proper
2485 As for ao-view.... some things are in the menu but don't do anything
2486 very useful. The developers have stopped working on ao-view to focus
2487 on a new, cross-platform ground station program. So ao-view may or
2488 may not be updated in the future. Mostly you just use
2489 the Log and Device menus. It has a wonderful display of the incoming
2490 flight data and I am sure you will enjoy what it has to say to you
2491 once you enable the voice output!
2495 <title>Calibration</title>
2497 There are only two calibrations required for a TeleMetrum board, and
2498 only one for TeleDongle and TeleMini. All boards are shipped from
2499 the factory pre-calibrated, but the procedures are documented here
2500 in case they are ever needed. Re-calibration is not supported by
2501 AltosUI, you must connect to the board with a serial terminal program
2502 and interact directly with the on-board command interpreter to effect
2506 <title>Radio Frequency</title>
2508 The radio frequency is synthesized from a clock based on the 48 MHz
2509 crystal on the board. The actual frequency of this oscillator
2510 must be measured to generate a calibration constant. While our
2512 bandwidth is wide enough to allow boards to communicate even when
2513 their oscillators are not on exactly the same frequency, performance
2514 is best when they are closely matched.
2515 Radio frequency calibration requires a calibrated frequency counter.
2516 Fortunately, once set, the variation in frequency due to aging and
2517 temperature changes is small enough that re-calibration by customers
2518 should generally not be required.
2521 To calibrate the radio frequency, connect the UHF antenna port to a
2522 frequency counter, set the board to 434.550MHz, and use the 'C'
2523 command in the on-board command interpreter to generate a CW
2524 carrier. For TeleMetrum, this is best done over USB. For TeleMini,
2525 note that the only way to escape the 'C' command is via power cycle
2526 since the board will no longer be listening for commands once it
2527 starts generating a CW carrier.
2530 Wait for the transmitter temperature to stabilize and the frequency
2531 to settle down. Then, divide 434.550 MHz by the
2532 measured frequency and multiply by the current radio cal value show
2533 in the 'c s' command. For an unprogrammed board, the default value
2534 is 1186611. Take the resulting integer and program it using the 'c f'
2535 command. Testing with the 'C' command again should show a carrier
2536 within a few tens of Hertz of the intended frequency.
2537 As with all 'c' sub-commands, follow this with a 'c w' to write the
2538 change to the parameter block in the on-board DataFlash chip.
2541 Note that any time you re-do the radio frequency calibration, the
2542 radio frequency is reset to the default 434.550 Mhz. If you want
2543 to use another frequency, you will have to set that again after
2544 calibration is completed.
2548 <title>TeleMetrum Accelerometer</title>
2550 The TeleMetrum accelerometer we use has its own 5 volt power
2552 the output must be passed through a resistive voltage divider to match
2553 the input of our 3.3 volt ADC. This means that unlike the barometric
2554 sensor, the output of the acceleration sensor is not ratio-metric to
2555 the ADC converter, and calibration is required. Explicitly
2556 calibrating the accelerometers also allows us to load any device
2557 from a Freescale family that includes at least +/- 40g, 50g, 100g,
2558 and 200g parts. Using gravity,
2559 a simple 2-point calibration yields acceptable results capturing both
2560 the different sensitivities and ranges of the different accelerometer
2561 parts and any variation in power supply voltages or resistor values
2562 in the divider network.
2565 To calibrate the acceleration sensor, use the 'c a 0' command. You
2566 will be prompted to orient the board vertically with the UHF antenna
2567 up and press a key, then to orient the board vertically with the
2568 UHF antenna down and press a key. Note that the accuracy of this
2569 calibration depends primarily on how perfectly vertical and still
2570 the board is held during the cal process. As with all 'c'
2571 sub-commands, follow this with a 'c w' to write the
2572 change to the parameter block in the on-board DataFlash chip.
2575 The +1g and -1g calibration points are included in each telemetry
2576 frame and are part of the header stored in onboard flash to be
2577 downloaded after flight. We always store and return raw ADC
2578 samples for each sensor... so nothing is permanently "lost" or
2579 "damaged" if the calibration is poor.
2582 In the unlikely event an accel cal goes badly, it is possible
2583 that TeleMetrum may always come up in 'pad mode' and as such not be
2584 listening to either the USB or radio link. If that happens,
2585 there is a special hook in the firmware to force the board back
2586 in to 'idle mode' so you can re-do the cal. To use this hook, you
2587 just need to ground the SPI clock pin at power-on. This pin is
2588 available as pin 2 on the 8-pin companion connector, and pin 1 is
2589 ground. So either carefully install a fine-gauge wire jumper
2590 between the two pins closest to the index hole end of the 8-pin
2591 connector, or plug in the programming cable to the 8-pin connector
2592 and use a small screwdriver or similar to short the two pins closest
2593 to the index post on the 4-pin end of the programming cable, and
2594 power up the board. It should come up in 'idle mode' (two beeps),
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