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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 Our second device was 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 such as the LipoCharger product included in TeleMini Starter Kits,
176 and connecting that via a USB cable to a laptop or other USB
180 The other active device in the starter kit is the TeleDongle USB to
181 RF interface. If you plug it in to your Mac or Linux computer it should
182 "just work", showing up as a serial port device. Windows systems need
183 driver information that is part of the AltOS download to know that the
184 existing USB modem driver will work. We therefore recommend installing
185 our software before plugging in TeleDongle if you are using a Windows
186 computer. If you are using Linux and are having problems, try moving
187 to a fresher kernel (2.6.33 or newer), as the USB serial driver had
188 ugly bugs in some earlier versions.
191 Next you should obtain and install the AltOS software. These include
192 the AltosUI ground station program, current firmware images for
193 TeleMetrum, TeleMini and TeleDongle, and a number of standalone
194 utilities that are rarely needed. Pre-built binary packages are
195 available for Linux, Microsoft Windows, and recent MacOSX versions.
196 Full source code and build instructions are also available.
197 The latest version may always be downloaded from
198 <ulink url="http://altusmetrum.org/AltOS"/>.
202 <title>Handling Precautions</title>
204 All Altus Metrum products are sophisticated electronic devices.
205 When handled gently and properly installed in an air-frame, they
206 will deliver impressive results. However, as with all electronic
207 devices, there are some precautions you must take.
210 The Lithium Polymer rechargeable batteries have an
211 extraordinary power density. This is great because we can fly with
212 much less battery mass than if we used alkaline batteries or previous
213 generation rechargeable batteries... but if they are punctured
214 or their leads are allowed to short, they can and will release their
216 Thus we recommend that you take some care when handling our batteries
217 and consider giving them some extra protection in your air-frame. We
218 often wrap them in suitable scraps of closed-cell packing foam before
219 strapping them down, for example.
222 The barometric sensors used on both TeleMetrum and TeleMini are
223 sensitive to sunlight. In normal TeleMetrum mounting situations, it
224 and all of the other surface mount components
225 are "down" towards whatever the underlying mounting surface is, so
226 this is not normally a problem. Please consider this, though, when
227 designing an installation, for example, in an air-frame with a
228 see-through plastic payload bay. It is particularly important to
229 consider this with TeleMini, both because the baro sensor is on the
230 "top" of the board, and because many model rockets with payload bays
231 use clear plastic for the payload bay! Replacing these with an opaque
232 cardboard tube, painting them, or wrapping them with a layer of masking
233 tape are all reasonable approaches to keep the sensor out of direct
237 The barometric sensor sampling port must be able to "breathe",
238 both by not being covered by foam or tape or other materials that might
239 directly block the hole on the top of the sensor, and also by having a
240 suitable static vent to outside air.
243 As with all other rocketry electronics, Altus Metrum altimeters must
244 be protected from exposure to corrosive motor exhaust and ejection
249 <title>Hardware Overview</title>
251 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
252 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
253 small in diameter may require some creativity in mounting and wiring
254 to succeed! The presence of an accelerometer means TeleMetrum should
255 be aligned along the flight axis of the airframe, and by default the 1/4
256 wave UHF wire antenna should be on the nose-cone end of the board. The
257 antenna wire is about 7 inches long, and wiring for a power switch and
258 the e-matches for apogee and main ejection charges depart from the
259 fin can end of the board, meaning an ideal "simple" avionics
260 bay for TeleMetrum should have at least 10 inches of interior length.
263 TeleMini is a 0.5 inch by 1.5 inch circuit board. It was designed to
264 fit inside an 18mm air-frame tube, but using it in a tube that
265 small in diameter may require some creativity in mounting and wiring
266 to succeed! Since there is no accelerometer, TeleMini can be mounted
267 in any convenient orientation. The default 1/4
268 wave UHF wire antenna attached to the center of one end of
269 the board is about 7 inches long, and wiring for a power switch and
270 the e-matches for apogee and main ejection charges depart from the
271 other end of the board, meaning an ideal "simple" avionics
272 bay for TeleMini should have at least 9 inches of interior length.
275 A typical TeleMetrum or TeleMini installation involves attaching
276 only a suitable Lithium Polymer battery, a single pole switch for
277 power on/off, and two pairs of wires connecting e-matches for the
278 apogee and main ejection charges. All Altus Metrum products are
279 designed for use with single-cell batteries with 3.7 volts nominal.
282 The battery connectors are a standard 2-pin JST connector and
283 match batteries sold by Spark Fun. These batteries are
284 single-cell Lithium Polymer batteries that nominally provide 3.7
285 volts. Other vendors sell similar batteries for RC aircraft
286 using mating connectors, however the polarity for those is
287 generally reversed from the batteries used by Altus Metrum
288 products. In particular, the Tenergy batteries supplied for use
289 in Featherweight flight computers are not compatible with Altus
290 Metrum flight computers or battery chargers. <emphasis>Check
291 polarity and voltage before connecting any battery not purchased
292 from Altus Metrum or Spark Fun.</emphasis>
295 By default, we use the unregulated output of the Li-Po battery directly
296 to fire ejection charges. This works marvelously with standard
297 low-current e-matches like the J-Tek from MJG Technologies, and with
298 Quest Q2G2 igniters. However, if you want or need to use a separate
299 pyro battery, check out the "External Pyro Battery" section in this
300 manual for instructions on how to wire that up. The altimeters are
301 designed to work with an external pyro battery of no more than 15 volts.
304 Ejection charges are wired directly to the screw terminal block
305 at the aft end of the altimeter. You'll need a very small straight
306 blade screwdriver for these screws, such as you might find in a
307 jeweler's screwdriver set.
310 TeleMetrum also uses the screw terminal block for the power
311 switch leads. On TeleMini, the power switch leads are soldered
312 directly to the board and can be connected directly to a switch.
315 For most air-frames, the integrated antennas are more than
316 adequate. However, if you are installing in a carbon-fiber or
317 metal electronics bay which is opaque to RF signals, you may need to
318 use off-board external antennas instead. In this case, you can
319 order an altimeter with an SMA connector for the UHF antenna
320 connection, and, on TeleMetrum, you can unplug the integrated GPS
321 antenna and select an appropriate off-board GPS antenna with
322 cable terminating in a U.FL connector.
326 <title>System Operation</title>
328 <title>Firmware Modes </title>
330 The AltOS firmware build for the altimeters has two
331 fundamental modes, "idle" and "flight". Which of these modes
332 the firmware operates in is determined at start up time. For
333 TeleMetrum, the mode is controlled by the orientation of the
334 rocket (well, actually the board, of course...) at the time
335 power is switched on. If the rocket is "nose up", then
336 TeleMetrum assumes it's on a rail or rod being prepared for
337 launch, so the firmware chooses flight mode. However, if the
338 rocket is more or less horizontal, the firmware instead enters
339 idle mode. Since TeleMini doesn't have an accelerometer we can
340 use to determine orientation, "idle" mode is selected when the
341 board receives a command packet within the first five seconds
342 of operation; if no packet is received, the board enters
346 At power on, you will hear three beeps or see three flashes
347 ("S" in Morse code for start up) and then a pause while
348 the altimeter completes initialization and self test, and decides
349 which mode to enter next.
352 In flight or "pad" mode, the altimeter engages the flight
353 state machine, goes into transmit-only mode to
354 send telemetry, and waits for launch to be detected.
355 Flight mode is indicated by an "di-dah-dah-dit" ("P" for pad)
356 on the beeper or lights, followed by beeps or flashes
357 indicating the state of the pyrotechnic igniter continuity.
358 One beep/flash indicates apogee continuity, two beeps/flashes
359 indicate main continuity, three beeps/flashes indicate both
360 apogee and main continuity, and one longer "brap" sound or
361 rapidly alternating lights indicates no continuity. For a
362 dual deploy flight, make sure you're getting three beeps or
363 flashes before launching! For apogee-only or motor eject
364 flights, do what makes sense.
367 If idle mode is entered, you will hear an audible "di-dit" or see
368 two short flashes ("I" for idle), and the flight state machine is
369 disengaged, thus no ejection charges will fire. The altimeters also
370 listen for the radio link when in idle mode for requests sent via
371 TeleDongle. Commands can be issued to a TeleMetrum in idle mode
373 USB or the radio link equivalently. TeleMini only has the radio link.
374 Idle mode is useful for configuring the altimeter, for extracting data
375 from the on-board storage chip after flight, and for ground testing
379 One "neat trick" of particular value when TeleMetrum is used with
380 very large air-frames, is that you can power the board up while the
381 rocket is horizontal, such that it comes up in idle mode. Then you can
382 raise the air-frame to launch position, and issue a 'reset' command
383 via TeleDongle over the radio link to cause the altimeter to reboot and
384 come up in flight mode. This is much safer than standing on the top
385 step of a rickety step-ladder or hanging off the side of a launch
386 tower with a screw-driver trying to turn on your avionics before
390 TeleMini is configured via the radio link. Of course, that
391 means you need to know the TeleMini radio configuration values
392 or you won't be able to communicate with it. For situations
393 when you don't have the radio configuration values, TeleMini
394 offers an 'emergency recovery' mode. In this mode, TeleMini is
395 configured as follows:
398 Sets the radio frequency to 434.550MHz
401 Sets the radio calibration back to the factory value.
404 Sets the callsign to N0CALL
407 Does not go to 'pad' mode after five seconds.
412 To get into 'emergency recovery' mode, first find the row of
413 four small holes opposite the switch wiring. Using a short
414 piece of small gauge wire, connect the outer two holes
415 together, then power TeleMini up. Once the red LED is lit,
416 disconnect the wire and the board should signal that it's in
417 'idle' mode after the initial five second startup period.
423 TeleMetrum includes a complete GPS receiver. A complete explanation
424 of how GPS works is beyond the scope of this manual, but the bottom
425 line is that the TeleMetrum GPS receiver needs to lock onto at least
426 four satellites to obtain a solid 3 dimensional position fix and know
430 TeleMetrum provides backup power to the GPS chip any time a
431 battery is connected. This allows the receiver to "warm start" on
432 the launch rail much faster than if every power-on were a GPS
433 "cold start". In typical operations, powering up TeleMetrum
434 on the flight line in idle mode while performing final air-frame
435 preparation will be sufficient to allow the GPS receiver to cold
436 start and acquire lock. Then the board can be powered down during
437 RSO review and installation on a launch rod or rail. When the board
438 is turned back on, the GPS system should lock very quickly, typically
439 long before igniter installation and return to the flight line are
444 <title>Controlling An Altimeter Over The Radio Link</title>
446 One of the unique features of the Altus Metrum system is
447 the ability to create a two way command link between TeleDongle
448 and an altimeter using the digital radio transceivers built into
449 each device. This allows you to interact with the altimeter from
450 afar, as if it were directly connected to the computer.
453 Any operation which can be performed with TeleMetrum can
454 either be done with TeleMetrum directly connected to the
455 computer via the USB cable, or through the radio
456 link. TeleMini doesn't provide a USB connector and so it is
457 always communicated with over radio. Select the appropriate
458 TeleDongle device when the list of devices is presented and
459 AltosUI will interact with an altimeter over the radio link.
462 One oddity in the current interface is how AltosUI selects the
463 frequency for radio communications. Instead of providing
464 an interface to specifically configure the frequency, it uses
465 whatever frequency was most recently selected for the target
466 TeleDongle device in Monitor Flight mode. If you haven't ever
467 used that mode with the TeleDongle in question, select the
468 Monitor Flight button from the top level UI, and pick the
469 appropriate TeleDongle device. Once the flight monitoring
470 window is open, select the desired frequency and then close it
471 down again. All radio communications will now use that frequency.
476 Save Flight Data—Recover flight data from the rocket without
482 Configure altimeter apogee delays or main deploy heights
483 to respond to changing launch conditions. You can also
484 'reboot' the altimeter. Use this to remotely enable the
485 flight computer by turning TeleMetrum on in "idle" mode,
486 then once the air-frame is oriented for launch, you can
487 reboot the altimeter and have it restart in pad mode
488 without having to climb the scary ladder.
493 Fire Igniters—Test your deployment charges without snaking
494 wires out through holes in the air-frame. Simply assembly the
495 rocket as if for flight with the apogee and main charges
496 loaded, then remotely command the altimeter to fire the
502 Operation over the radio link for configuring an altimeter, ground
503 testing igniters, and so forth uses the same RF frequencies as flight
504 telemetry. To configure the desired TeleDongle frequency, select
505 the monitor flight tab, then use the frequency selector and
506 close the window before performing other desired radio operations.
509 TeleMetrum only enables radio commanding in 'idle' mode, so
510 make sure you have TeleMetrum lying horizontally when you turn
511 it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
512 flight, and will not be listening for command packets from TeleDongle.
515 TeleMini listens for a command packet for five seconds after
516 first being turned on, if it doesn't hear anything, it enters
517 'pad' mode, ready for flight and will no longer listen for
518 command packets. The easiest way to connect to TeleMini is to
519 initiate the command and select the TeleDongle device. At this
520 point, the TeleDongle will be attempting to communicate with
521 the TeleMini. Now turn TeleMini on, and it should immediately
522 start communicating with the TeleDongle and the desired
523 operation can be performed.
526 You can monitor the operation of the radio link by watching the
527 lights on the devices. The red LED will flash each time a packet
528 is transmitted, while the green LED will light up on TeleDongle when
529 it is waiting to receive a packet from the altimeter.
533 <title>Ground Testing </title>
535 An important aspect of preparing a rocket using electronic deployment
536 for flight is ground testing the recovery system. Thanks
537 to the bi-directional radio link central to the Altus Metrum system,
538 this can be accomplished in a TeleMetrum or TeleMini equipped rocket
539 with less work than you may be accustomed to with other systems. It
543 Just prep the rocket for flight, then power up the altimeter
544 in "idle" mode (placing air-frame horizontal for TeleMetrum or
545 selected the Configure Altimeter tab for TeleMini). This will cause
546 the firmware to go into "idle" mode, in which the normal flight
547 state machine is disabled and charges will not fire without
548 manual command. You can now command the altimeter to fire the apogee
549 or main charges from a safe distance using your computer and
550 TeleDongle and the Fire Igniter tab to complete ejection testing.
554 <title>Radio Link </title>
556 The chip our boards are based on incorporates an RF transceiver, but
557 it's not a full duplex system... each end can only be transmitting or
558 receiving at any given moment. So we had to decide how to manage the
562 By design, the altimeter firmware listens for the radio link when
563 it's in "idle mode", which
564 allows us to use the radio link to configure the rocket, do things like
565 ejection tests, and extract data after a flight without having to
566 crack open the air-frame. However, when the board is in "flight
567 mode", the altimeter only
568 transmits and doesn't listen at all. That's because we want to put
569 ultimate priority on event detection and getting telemetry out of
571 the radio in case the rocket crashes and we aren't able to extract
575 We don't use a 'normal packet radio' mode like APRS because they're
576 just too inefficient. The GFSK modulation we use is FSK with the
577 base-band pulses passed through a
578 Gaussian filter before they go into the modulator to limit the
579 transmitted bandwidth. When combined with the hardware forward error
580 correction support in the cc1111 chip, this allows us to have a very
581 robust 38.4 kilobit data link with only 10 milliwatts of transmit
582 power, a whip antenna in the rocket, and a hand-held Yagi on the
583 ground. We've had flights to above 21k feet AGL with great reception,
584 and calculations suggest we should be good to well over 40k feet AGL
585 with a 5-element yagi on the ground. We hope to fly boards to higher
586 altitudes over time, and would of course appreciate customer feedback
587 on performance in higher altitude flights!
591 <title>Configurable Parameters</title>
593 Configuring an Altus Metrum altimeter for flight is very
594 simple. Even on our baro-only TeleMini board, the use of a Kalman
595 filter means there is no need to set a "mach delay". The few
596 configurable parameters can all be set using AltosUI over USB or
597 or radio link via TeleDongle.
600 <title>Radio Frequency</title>
602 Altus Metrum boards support radio frequencies in the 70cm
603 band. By default, the configuration interface provides a
604 list of 10 "standard" frequencies in 100kHz channels starting at
605 434.550MHz. However, the firmware supports use of
606 any 50kHz multiple within the 70cm band. At any given
607 launch, we highly recommend coordinating when and by whom each
608 frequency will be used to avoid interference. And of course, both
609 altimeter and TeleDongle must be configured to the same
610 frequency to successfully communicate with each other.
614 <title>Apogee Delay</title>
616 Apogee delay is the number of seconds after the altimeter detects flight
617 apogee that the drogue charge should be fired. In most cases, this
618 should be left at the default of 0. However, if you are flying
619 redundant electronics such as for an L3 certification, you may wish
620 to set one of your altimeters to a positive delay so that both
621 primary and backup pyrotechnic charges do not fire simultaneously.
624 The Altus Metrum apogee detection algorithm fires exactly at
625 apogee. If you are also flying an altimeter like the
626 PerfectFlite MAWD, which only supports selecting 0 or 1
627 seconds of apogee delay, you may wish to set the MAWD to 0
628 seconds delay and set the TeleMetrum to fire your backup 2
629 or 3 seconds later to avoid any chance of both charges
630 firing simultaneously. We've flown several air-frames this
631 way quite happily, including Keith's successful L3 cert.
635 <title>Main Deployment Altitude</title>
637 By default, the altimeter will fire the main deployment charge at an
638 elevation of 250 meters (about 820 feet) above ground. We think this
639 is a good elevation for most air-frames, but feel free to change this
640 to suit. In particular, if you are flying two altimeters, you may
642 deployment elevation for the backup altimeter to be something lower
643 than the primary so that both pyrotechnic charges don't fire
648 <title>Maximum Flight Log</title>
650 TeleMetrum version 1.1 and 1.2 have 2MB of on-board flash storage,
651 enough to hold over 40 minutes of data at full data rate
652 (100 samples/second). TeleMetrum 1.0 has 1MB of on-board
653 storage. As data are stored at a reduced rate during descent
654 (10 samples/second), there's plenty of space to store many
655 flights worth of data.
658 The on-board flash is partitioned into separate flight logs,
659 each of a fixed maximum size. Increase the maximum size of
660 each log and you reduce the number of flights that can be
661 stored. Decrease the size and TeleMetrum can store more
665 All of the configuration data is also stored in the flash
666 memory, which consumes 64kB on TeleMetrum v1.1/v1.2 and 256B on
667 TeleMetrum v1.0. This configuration space is not available
668 for storing flight log data.
671 To compute the amount of space needed for a single flight,
672 you can multiply the expected ascent time (in seconds) by
673 800, multiply the expected descent time (in seconds) by 80
674 and add the two together. That will slightly under-estimate
675 the storage (in bytes) needed for the flight. For instance,
676 a flight spending 20 seconds in ascent and 150 seconds in
677 descent will take about (20 * 800) + (150 * 80) = 28000
678 bytes of storage. You could store dozens of these flights in
682 The default size, 192kB, allows for 10 flights of storage on
683 TeleMetrum v1.1/v1.2 and 5 flights on TeleMetrum v1.0. This
684 ensures that you won't need to erase the memory before
685 flying each time while still allowing more than sufficient
686 storage for each flight.
689 As TeleMini does not contain an accelerometer, it stores
690 data at 10 samples per second during ascent and one sample
691 per second during descent. Each sample is a two byte reading
692 from the barometer. These are stored in 5kB of
693 on-chip flash memory which can hold 256 seconds at the
694 ascent rate or 2560 seconds at the descent rate. Because of
695 the limited storage, TeleMini cannot hold data for more than
696 one flight, and so must be erased after each flight or it
697 will not capture data for subsequent flights.
701 <title>Ignite Mode</title>
703 Instead of firing one charge at apogee and another charge at
704 a fixed height above the ground, you can configure the
705 altimeter to fire both at apogee or both during
706 descent. This was added to support an airframe that has two
707 TeleMetrum computers, one in the fin can and one in the
711 Providing the ability to use both igniters for apogee or
712 main allows some level of redundancy without needing two
713 flight computers. In Redundant Apogee or Redundant Main
714 mode, the two charges will be fired two seconds apart.
718 <title>Pad Orientation</title>
720 TeleMetrum measures acceleration along the axis of the
721 board. Which way the board is oriented affects the sign of
722 the acceleration value. Instead of trying to guess which way
723 the board is mounted in the air frame, TeleMetrum must be
724 explicitly configured for either Antenna Up or Antenna
725 Down. The default, Antenna Up, expects the end of the
726 TeleMetrum board connected to the 70cm antenna to be nearest
727 the nose of the rocket, with the end containing the screw
728 terminals nearest the tail.
736 <title>AltosUI</title>
738 The AltosUI program provides a graphical user interface for
739 interacting with the Altus Metrum product family, including
740 TeleMetrum, TeleMini and TeleDongle. AltosUI can monitor telemetry data,
741 configure TeleMetrum, TeleMini and TeleDongle devices and many other
742 tasks. The primary interface window provides a selection of
743 buttons, one for each major activity in the system. This manual
744 is split into chapters, each of which documents one of the tasks
745 provided from the top-level toolbar.
748 <title>Monitor Flight</title>
749 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
751 Selecting this item brings up a dialog box listing all of the
752 connected TeleDongle devices. When you choose one of these,
753 AltosUI will create a window to display telemetry data as
754 received by the selected TeleDongle device.
757 All telemetry data received are automatically recorded in
758 suitable log files. The name of the files includes the current
759 date and rocket serial and flight numbers.
762 The radio frequency being monitored by the TeleDongle device is
763 displayed at the top of the window. You can configure the
764 frequency by clicking on the frequency box and selecting the desired
765 frequency. AltosUI remembers the last frequency selected for each
766 TeleDongle and selects that automatically the next time you use
770 Below the TeleDongle frequency selector, the window contains a few
771 significant pieces of information about the altimeter providing
772 the telemetry data stream:
776 <para>The configured call-sign</para>
779 <para>The device serial number</para>
782 <para>The flight number. Each altimeter remembers how many
788 The rocket flight state. Each flight passes through several
789 states including Pad, Boost, Fast, Coast, Drogue, Main and
795 The Received Signal Strength Indicator value. This lets
796 you know how strong a signal TeleDongle is receiving. The
797 radio inside TeleDongle operates down to about -99dBm;
798 weaker signals may not be receivable. The packet link uses
799 error detection and correction techniques which prevent
800 incorrect data from being reported.
805 The age of the displayed data, in seconds since the last
806 successfully received telemetry packet. In normal operation
807 this will stay in the low single digits. If the number starts
808 counting up, then you are no longer receiving data over the radio
809 link from the flight computer.
814 Finally, the largest portion of the window contains a set of
815 tabs, each of which contain some information about the rocket.
816 They're arranged in 'flight order' so that as the flight
817 progresses, the selected tab automatically switches to display
818 data relevant to the current state of the flight. You can select
819 other tabs at any time. The final 'table' tab displays all of
820 the raw telemetry values in one place in a spreadsheet-like format.
823 <title>Launch Pad</title>
825 The 'Launch Pad' tab shows information used to decide when the
826 rocket is ready for flight. The first elements include red/green
827 indicators, if any of these is red, you'll want to evaluate
828 whether the rocket is ready to launch:
832 Battery Voltage. This indicates whether the Li-Po battery
833 powering the TeleMetrum has sufficient charge to last for
834 the duration of the flight. A value of more than
835 3.7V is required for a 'GO' status.
840 Apogee Igniter Voltage. This indicates whether the apogee
841 igniter has continuity. If the igniter has a low
842 resistance, then the voltage measured here will be close
843 to the Li-Po battery voltage. A value greater than 3.2V is
844 required for a 'GO' status.
849 Main Igniter Voltage. This indicates whether the main
850 igniter has continuity. If the igniter has a low
851 resistance, then the voltage measured here will be close
852 to the Li-Po battery voltage. A value greater than 3.2V is
853 required for a 'GO' status.
858 On-board Data Logging. This indicates whether there is
859 space remaining on-board to store flight data for the
860 upcoming flight. If you've downloaded data, but failed
861 to erase flights, there may not be any space
862 left. TeleMetrum can store multiple flights, depending
863 on the configured maximum flight log size. TeleMini
864 stores only a single flight, so it will need to be
865 downloaded and erased after each flight to capture
866 data. This only affects on-board flight logging; the
867 altimeter will still transmit telemetry and fire
868 ejection charges at the proper times.
873 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
874 currently able to compute position information. GPS requires
875 at least 4 satellites to compute an accurate position.
880 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
881 10 consecutive positions without losing lock. This ensures
882 that the GPS receiver has reliable reception from the
888 The Launchpad tab also shows the computed launch pad position
889 and altitude, averaging many reported positions to improve the
895 <title>Ascent</title>
897 This tab is shown during Boost, Fast and Coast
898 phases. The information displayed here helps monitor the
899 rocket as it heads towards apogee.
902 The height, speed and acceleration are shown along with the
903 maximum values for each of them. This allows you to quickly
904 answer the most commonly asked questions you'll hear during
908 The current latitude and longitude reported by the TeleMetrum GPS are
909 also shown. Note that under high acceleration, these values
910 may not get updated as the GPS receiver loses position
911 fix. Once the rocket starts coasting, the receiver should
912 start reporting position again.
915 Finally, the current igniter voltages are reported as in the
916 Launch Pad tab. This can help diagnose deployment failures
917 caused by wiring which comes loose under high acceleration.
921 <title>Descent</title>
923 Once the rocket has reached apogee and (we hope) activated the
924 apogee charge, attention switches to tracking the rocket on
925 the way back to the ground, and for dual-deploy flights,
926 waiting for the main charge to fire.
929 To monitor whether the apogee charge operated correctly, the
930 current descent rate is reported along with the current
931 height. Good descent rates vary based on the choice of recovery
932 components, but generally range from 15-30m/s on drogue and should
933 be below 10m/s when under the main parachute in a dual-deploy flight.
936 For TeleMetrum altimeters, you can locate the rocket in the
937 sky using the elevation and bearing information to figure
938 out where to look. Elevation is in degrees above the
939 horizon. Bearing is reported in degrees relative to true
940 north. Range can help figure out how big the rocket will
941 appear. Ground Distance shows how far it is to a point
942 directly under the rocket and can help figure out where the
943 rocket is likely to land. Note that all of these values are
944 relative to the pad location. If the elevation is near 90°,
945 the rocket is over the pad, not over you.
948 Finally, the igniter voltages are reported in this tab as
949 well, both to monitor the main charge as well as to see what
950 the status of the apogee charge is. Note that some commercial
951 e-matches are designed to retain continuity even after being
952 fired, and will continue to show as green or return from red to
957 <title>Landed</title>
959 Once the rocket is on the ground, attention switches to
960 recovery. While the radio signal is often lost once the
961 rocket is on the ground, the last reported GPS position is
962 generally within a short distance of the actual landing location.
965 The last reported GPS position is reported both by
966 latitude and longitude as well as a bearing and distance from
967 the launch pad. The distance should give you a good idea of
968 whether to walk or hitch a ride. Take the reported
969 latitude and longitude and enter them into your hand-held GPS
970 unit and have that compute a track to the landing location.
973 Both TeleMini and TeleMetrum will continue to transmit RDF
974 tones after landing, allowing you to locate the rocket by
975 following the radio signal if necessary. You may need to get
976 away from the clutter of the flight line, or even get up on
977 a hill (or your neighbor's RV roof) to receive the RDF signal.
980 The maximum height, speed and acceleration reported
981 during the flight are displayed for your admiring observers.
982 The accuracy of these immediate values depends on the quality
983 of your radio link and how many packets were received.
984 Recovering the on-board data after flight will likely yield
985 more precise results.
988 To get more detailed information about the flight, you can
989 click on the 'Graph Flight' button which will bring up a
990 graph window for the current flight.
994 <title>Site Map</title>
996 When the TeleMetrum has a GPS fix, the Site Map tab will map
997 the rocket's position to make it easier for you to locate the
998 rocket, both while it is in the air, and when it has landed. The
999 rocket's state is indicated by color: white for pad, red for
1000 boost, pink for fast, yellow for coast, light blue for drogue,
1001 dark blue for main, and black for landed.
1004 The map's scale is approximately 3m (10ft) per pixel. The map
1005 can be dragged using the left mouse button. The map will attempt
1006 to keep the rocket roughly centered while data is being received.
1009 Images are fetched automatically via the Google Maps Static API,
1010 and cached on disk for reuse. If map images cannot be downloaded,
1011 the rocket's path will be traced on a dark gray background
1015 You can pre-load images for your favorite launch sites
1016 before you leave home; check out the 'Preload Maps' section below.
1021 <title>Save Flight Data</title>
1023 The altimeter records flight data to its internal flash memory.
1024 TeleMetrum data is recorded at a much higher rate than the telemetry
1025 system can handle, and is not subject to radio drop-outs. As
1026 such, it provides a more complete and precise record of the
1027 flight. The 'Save Flight Data' button allows you to read the
1028 flash memory and write it to disk. As TeleMini has only a barometer, it
1029 records data at the same rate as the telemetry signal, but there will be
1030 no data lost due to telemetry drop-outs.
1033 Clicking on the 'Save Flight Data' button brings up a list of
1034 connected TeleMetrum and TeleDongle devices. If you select a
1035 TeleMetrum device, the flight data will be downloaded from that
1036 device directly. If you select a TeleDongle device, flight data
1037 will be downloaded from an altimeter over radio link via the
1038 specified TeleDongle. See the chapter on Controlling An Altimeter
1039 Over The Radio Link for more information.
1042 After the device has been selected, a dialog showing the
1043 flight data saved in the device will be shown allowing you to
1044 select which flights to download and which to delete. With
1045 version 0.9 or newer firmware, you must erase flights in order
1046 for the space they consume to be reused by another
1047 flight. This prevents accidentally losing flight data
1048 if you neglect to download data before flying again. Note that
1049 if there is no more space available in the device, then no
1050 data will be recorded during the next flight.
1053 The file name for each flight log is computed automatically
1054 from the recorded flight date, altimeter serial number and
1055 flight number information.
1059 <title>Replay Flight</title>
1061 Select this button and you are prompted to select a flight
1062 record file, either a .telem file recording telemetry data or a
1063 .eeprom file containing flight data saved from the altimeter
1067 Once a flight record is selected, the flight monitor interface
1068 is displayed and the flight is re-enacted in real time. Check
1069 the Monitor Flight chapter above to learn how this window operates.
1073 <title>Graph Data</title>
1075 Select this button and you are prompted to select a flight
1076 record file, either a .telem file recording telemetry data or a
1077 .eeprom file containing flight data saved from
1081 Once a flight record is selected, a window with two tabs is
1082 opened. The first tab contains a graph with acceleration
1083 (blue), velocity (green) and altitude (red) of the flight,
1084 measured in metric units. The
1085 apogee(yellow) and main(magenta) igniter voltages are also
1086 displayed; high voltages indicate continuity, low voltages
1087 indicate open circuits. The second tab contains some basic
1091 The graph can be zoomed into a particular area by clicking and
1092 dragging down and to the right. Once zoomed, the graph can be
1093 reset by clicking and dragging up and to the left. Holding down
1094 control and clicking and dragging allows the graph to be panned.
1095 The right mouse button causes a pop-up menu to be displayed, giving
1096 you the option save or print the plot.
1099 Note that telemetry files will generally produce poor graphs
1100 due to the lower sampling rate and missed telemetry packets.
1101 Use saved flight data in .eeprom files for graphing where possible.
1105 <title>Export Data</title>
1107 This tool takes the raw data files and makes them available for
1108 external analysis. When you select this button, you are prompted to
1110 data file (either .eeprom or .telem will do, remember that
1111 .eeprom files contain higher resolution and more continuous
1112 data). Next, a second dialog appears which is used to select
1113 where to write the resulting file. It has a selector to choose
1114 between CSV and KML file formats.
1117 <title>Comma Separated Value Format</title>
1119 This is a text file containing the data in a form suitable for
1120 import into a spreadsheet or other external data analysis
1121 tool. The first few lines of the file contain the version and
1122 configuration information from the altimeter, then
1123 there is a single header line which labels all of the
1124 fields. All of these lines start with a '#' character which
1125 many tools can be configured to skip over.
1128 The remaining lines of the file contain the data, with each
1129 field separated by a comma and at least one space. All of
1130 the sensor values are converted to standard units, with the
1131 barometric data reported in both pressure, altitude and
1132 height above pad units.
1136 <title>Keyhole Markup Language (for Google Earth)</title>
1138 This is the format used by Google Earth to provide an overlay
1139 within that application. With this, you can use Google Earth to
1140 see the whole flight path in 3D.
1145 <title>Configure Altimeter</title>
1147 Select this button and then select either a TeleMetrum or
1148 TeleDongle Device from the list provided. Selecting a TeleDongle
1149 device will use the radio link to configure a remote altimeter.
1152 The first few lines of the dialog provide information about the
1153 connected device, including the product name,
1154 software version and hardware serial number. Below that are the
1155 individual configuration entries.
1158 At the bottom of the dialog, there are four buttons:
1163 Save. This writes any changes to the
1164 configuration parameter block in flash memory. If you don't
1165 press this button, any changes you make will be lost.
1170 Reset. This resets the dialog to the most recently saved values,
1171 erasing any changes you have made.
1176 Reboot. This reboots the device. Use this to
1177 switch from idle to pad mode by rebooting once the rocket is
1178 oriented for flight, or to confirm changes you think you saved
1184 Close. This closes the dialog. Any unsaved changes will be
1190 The rest of the dialog contains the parameters to be configured.
1193 <title>Main Deploy Altitude</title>
1195 This sets the altitude (above the recorded pad altitude) at
1196 which the 'main' igniter will fire. The drop-down menu shows
1197 some common values, but you can edit the text directly and
1198 choose whatever you like. If the apogee charge fires below
1199 this altitude, then the main charge will fire two seconds
1200 after the apogee charge fires.
1204 <title>Apogee Delay</title>
1206 When flying redundant electronics, it's often important to
1207 ensure that multiple apogee charges don't fire at precisely
1208 the same time, as that can over pressurize the apogee deployment
1209 bay and cause a structural failure of the air-frame. The Apogee
1210 Delay parameter tells the flight computer to fire the apogee
1211 charge a certain number of seconds after apogee has been
1216 <title>Radio Frequency</title>
1218 This configures which of the configured frequencies to use for both
1219 telemetry and packet command mode. Note that if you set this
1220 value via packet command mode, you will have to reconfigure
1221 the TeleDongle frequency before you will be able to use packet
1226 <title>Radio Calibration</title>
1228 The radios in every Altus Metrum device are calibrated at the
1229 factory to ensure that they transmit and receive on the
1230 specified frequency. If you need to you can adjust the calibration
1231 by changing this value. Do not do this without understanding what
1232 the value means, read the appendix on calibration and/or the source
1233 code for more information. To change a TeleDongle's calibration,
1234 you must reprogram the unit completely.
1238 <title>Callsign</title>
1240 This sets the call sign included in each telemetry packet. Set this
1241 as needed to conform to your local radio regulations.
1245 <title>Maximum Flight Log Size</title>
1247 This sets the space (in kilobytes) allocated for each flight
1248 log. The available space will be divided into chunks of this
1249 size. A smaller value will allow more flights to be stored,
1250 a larger value will record data from longer flights.
1254 <title>Ignite Mode</title>
1256 TeleMetrum and TeleMini provide two igniter channels as they
1257 were originally designed as dual-deploy flight
1258 computers. This configuration parameter allows the two
1259 channels to be used in different configurations.
1264 Dual Deploy. This is the usual mode of operation; the
1265 'apogee' channel is fired at apogee and the 'main'
1266 channel at the height above ground specified by the
1267 'Main Deploy Altitude' during descent.
1272 Redundant Apogee. This fires both channels at
1273 apogee, the 'apogee' channel first followed after a two second
1274 delay by the 'main' channel.
1279 Redundant Main. This fires both channels at the
1280 height above ground specified by the Main Deploy
1281 Altitude setting during descent. The 'apogee'
1282 channel is fired first, followed after a two second
1283 delay by the 'main' channel.
1289 <title>Pad Orientation</title>
1291 Because it includes an accelerometer, TeleMetrum is
1292 sensitive to the orientation of the board. By default, it
1293 expects the antenna end to point forward. This parameter
1294 allows that default to be changed, permitting the board to
1295 be mounted with the antenna pointing aft instead.
1300 Antenna Up. In this mode, the antenna end of the
1301 TeleMetrum board must point forward, in line with the
1302 expected flight path.
1307 Antenna Down. In this mode, the antenna end of the
1308 TeleMetrum board must point aft, in line with the
1309 expected flight path.
1316 <title>Configure AltosUI</title>
1318 This button presents a dialog so that you can configure the AltosUI global settings.
1321 <title>Voice Settings</title>
1323 AltosUI provides voice announcements during flight so that you
1324 can keep your eyes on the sky and still get information about
1325 the current flight status. However, sometimes you don't want
1330 <para>Enable—turns all voice announcements on and off</para>
1334 Test Voice—Plays a short message allowing you to verify
1335 that the audio system is working and the volume settings
1342 <title>Log Directory</title>
1344 AltosUI logs all telemetry data and saves all TeleMetrum flash
1345 data to this directory. This directory is also used as the
1346 staring point when selecting data files for display or export.
1349 Click on the directory name to bring up a directory choosing
1350 dialog, select a new directory and click 'Select Directory' to
1351 change where AltosUI reads and writes data files.
1355 <title>Callsign</title>
1357 This value is transmitted in each command packet sent from
1358 TeleDongle and received from an altimeter. It is not used in
1359 telemetry mode, as the callsign configured in the altimeter board
1360 is included in all telemetry packets. Configure this
1361 with the AltosUI operators call sign as needed to comply with
1362 your local radio regulations.
1366 <title>Imperial Units</title>
1368 This switches between metric units (meters) and imperial
1369 units (feet and miles). This affects the display of values
1370 use during flight monitoring, data graphing and all of the
1371 voice announcements. It does not change the units used when
1372 exporting to CSV files, those are always produced in metric units.
1376 <title>Font Size</title>
1378 Selects the set of fonts used in the flight monitor
1379 window. Choose between the small, medium and large sets.
1383 <title>Serial Debug</title>
1385 This causes all communication with a connected device to be
1386 dumped to the console from which AltosUI was started. If
1387 you've started it from an icon or menu entry, the output
1388 will simply be discarded. This mode can be useful to debug
1389 various serial communication issues.
1393 <title>Manage Frequencies</title>
1395 This brings up a dialog where you can configure the set of
1396 frequencies shown in the various frequency menus. You can
1397 add as many as you like, or even reconfigure the default
1398 set. Changing this list does not affect the frequency
1399 settings of any devices, it only changes the set of
1400 frequencies shown in the menus.
1405 <title>Configure Groundstation</title>
1407 Select this button and then select a TeleDongle Device from the list provided.
1410 The first few lines of the dialog provide information about the
1411 connected device, including the product name,
1412 software version and hardware serial number. Below that are the
1413 individual configuration entries.
1416 Note that the TeleDongle itself doesn't save any configuration
1417 data, the settings here are recorded on the local machine in
1418 the Java preferences database. Moving the TeleDongle to
1419 another machine, or using a different user account on the same
1420 machine will cause settings made here to have no effect.
1423 At the bottom of the dialog, there are three buttons:
1428 Save. This writes any changes to the
1429 local Java preferences file. If you don't
1430 press this button, any changes you make will be lost.
1435 Reset. This resets the dialog to the most recently saved values,
1436 erasing any changes you have made.
1441 Close. This closes the dialog. Any unsaved changes will be
1447 The rest of the dialog contains the parameters to be configured.
1450 <title>Frequency</title>
1452 This configures the frequency to use for both telemetry and
1453 packet command mode. Set this before starting any operation
1454 involving packet command mode so that it will use the right
1455 frequency. Telemetry monitoring mode also provides a menu to
1456 change the frequency, and that menu also sets the same Java
1457 preference value used here.
1461 <title>Radio Calibration</title>
1463 The radios in every Altus Metrum device are calibrated at the
1464 factory to ensure that they transmit and receive on the
1465 specified frequency. To change a TeleDongle's calibration,
1466 you must reprogram the unit completely, so this entry simply
1467 shows the current value and doesn't allow any changes.
1472 <title>Flash Image</title>
1474 This reprograms any Altus Metrum device by using a TeleMetrum
1475 or TeleDongle as a programming dongle. Please read the
1476 directions for flashing devices in the Updating Device
1477 Firmware chapter below.
1480 Once you have the programmer and target devices connected,
1481 push the 'Flash Image' button. That will present a dialog box
1482 listing all of the connected devices. Carefully select the
1483 programmer device, not the device to be programmed.
1486 Next, select the image to flash to the device. These are named
1487 with the product name and firmware version. The file selector
1488 will start in the directory containing the firmware included
1489 with the AltosUI package. Navigate to the directory containing
1490 the desired firmware if it isn't there.
1493 Next, a small dialog containing the device serial number and
1494 RF calibration values should appear. If these values are
1495 incorrect (possibly due to a corrupted image in the device),
1496 enter the correct values here.
1499 Finally, a dialog containing a progress bar will follow the
1500 programming process.
1503 When programming is complete, the target device will
1504 reboot. Note that if the target device is connected via USB, you
1505 will have to unplug it and then plug it back in for the USB
1506 connection to reset so that you can communicate with the device
1511 <title>Fire Igniter</title>
1513 This activates the igniter circuits in TeleMetrum to help test
1514 recovery systems deployment. Because this command can operate
1515 over the Packet Command Link, you can prepare the rocket as
1516 for flight and then test the recovery system without needing
1517 to snake wires inside the air-frame.
1520 Selecting the 'Fire Igniter' button brings up the usual device
1521 selection dialog. Pick the desired TeleDongle or TeleMetrum
1522 device. This brings up another window which shows the current
1523 continuity test status for both apogee and main charges.
1526 Next, select the desired igniter to fire. This will enable the
1530 Select the 'Arm' button. This enables the 'Fire' button. The
1531 word 'Arm' is replaced by a countdown timer indicating that
1532 you have 10 seconds to press the 'Fire' button or the system
1533 will deactivate, at which point you start over again at
1534 selecting the desired igniter.
1538 <title>Scan Channels</title>
1540 This listens for telemetry packets on all of the configured
1541 frequencies, displaying information about each device it
1542 receives a packet from. You can select which of the three
1543 telemetry formats should be tried; by default, it only listens
1544 for the standard telemetry packets used in v1.0 and later
1549 <title>Load Maps</title>
1551 Before heading out to a new launch site, you can use this to
1552 load satellite images in case you don't have internet
1553 connectivity at the site. This loads a fairly large area
1554 around the launch site, which should cover any flight you're likely to make.
1557 There's a drop-down menu of launch sites we know about; if
1558 your favorites aren't there, please let us know the lat/lon
1559 and name of the site. The contents of this list are actually
1560 downloaded at run-time, so as new sites are sent in, they'll
1561 get automatically added to this list.
1564 If the launch site isn't in the list, you can manually enter the lat/lon values
1567 Clicking the 'Load Map' button will fetch images from Google
1568 Maps; note that Google limits how many images you can fetch at
1569 once, so if you load more than one launch site, you may get
1570 some gray areas in the map which indicate that Google is tired
1571 of sending data to you. Try again later.
1575 <title>Monitor Idle</title>
1577 This brings up a dialog similar to the Monitor Flight UI,
1578 except it works with the altimeter in "idle" mode by sending
1579 query commands to discover the current state rather than
1580 listening for telemetry packets.
1585 <title>Using Altus Metrum Products</title>
1587 <title>Being Legal</title>
1589 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
1590 other authorization to legally operate the radio transmitters that are part
1595 <title>In the Rocket</title>
1597 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
1598 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
1599 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
1600 850mAh battery weighs less than a 9V alkaline battery, and will
1601 run a TeleMetrum for hours.
1602 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
1603 a few hours, or a TeleMini for much (much) longer.
1606 By default, we ship the altimeters with a simple wire antenna. If your
1607 electronics bay or the air-frame it resides within is made of carbon fiber,
1608 which is opaque to RF signals, you may choose to have an SMA connector
1609 installed so that you can run a coaxial cable to an antenna mounted
1610 elsewhere in the rocket.
1614 <title>On the Ground</title>
1616 To receive the data stream from the rocket, you need an antenna and short
1617 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. If possible, use an SMA to BNC
1618 adapter instead of feedline between the antenna feedpoint and
1619 TeleDongle, as this will give you the best performance. The
1620 TeleDongle in turn plugs directly into the USB port on a notebook
1621 computer. Because TeleDongle looks like a simple serial port, your computer
1622 does not require special device drivers... just plug it in.
1625 The GUI tool, AltosUI, is written in Java and runs across
1626 Linux, Mac OS and Windows. There's also a suite of C tools
1627 for Linux which can perform most of the same tasks.
1630 After the flight, you can use the radio link to extract the more detailed data
1631 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
1632 TeleMetrum board directly. Pulling out the data without having to open up
1633 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
1634 battery, so you'll want one of those anyway... the same cable used by lots
1635 of digital cameras and other modern electronic stuff will work fine.
1638 If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
1639 receiver, so that you can put in a way-point for the last reported rocket
1640 position before touch-down. This makes looking for your rocket a lot like
1641 Geo-Caching... just go to the way-point and look around starting from there.
1644 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
1645 can use that with your antenna to direction-find the rocket on the ground
1646 the same way you can use a Walston or Beeline tracker. This can be handy
1647 if the rocket is hiding in sage brush or a tree, or if the last GPS position
1648 doesn't get you close enough because the rocket dropped into a canyon, or
1649 the wind is blowing it across a dry lake bed, or something like that... Keith
1650 and Bdale both currently own and use the Yaesu VX-7R at launches.
1653 So, to recap, on the ground the hardware you'll need includes:
1654 <orderedlist inheritnum='inherit' numeration='arabic'>
1656 an antenna and feed-line or adapter
1665 optionally, a hand-held GPS receiver
1668 optionally, an HT or receiver covering 435 MHz
1673 The best hand-held commercial directional antennas we've found for radio
1674 direction finding rockets are from
1675 <ulink url="http://www.arrowantennas.com/" >
1678 The 440-3 and 440-5 are both good choices for finding a
1679 TeleMetrum- or TeleMini- equipped rocket when used with a suitable
1680 70cm HT. TeleDongle and an SMA to BNC adapter fit perfectly
1681 between the driven element and reflector of Arrow antennas.
1685 <title>Data Analysis</title>
1687 Our software makes it easy to log the data from each flight, both the
1688 telemetry received during the flight itself, and the more
1689 complete data log recorded in the flash memory on the altimeter
1690 board. Once this data is on your computer, our post-flight tools make it
1691 easy to quickly get to the numbers everyone wants, like apogee altitude,
1692 max acceleration, and max velocity. You can also generate and view a
1693 standard set of plots showing the altitude, acceleration, and
1694 velocity of the rocket during flight. And you can even export a TeleMetrum data file
1695 usable with Google Maps and Google Earth for visualizing the flight path
1696 in two or three dimensions!
1699 Our ultimate goal is to emit a set of files for each flight that can be
1700 published as a web page per flight, or just viewed on your local disk with
1705 <title>Future Plans</title>
1707 In the future, we intend to offer "companion boards" for the rocket
1708 that will plug in to TeleMetrum to collect additional data, provide
1709 more pyro channels, and so forth.
1712 Also under design is a new flight computer with more sensors, more
1713 pyro channels, and a more powerful radio system designed for use
1714 in multi-stage, complex, and extreme altitude projects.
1717 We are also working on alternatives to TeleDongle. One is a
1718 a stand-alone, hand-held ground terminal that will allow monitoring
1719 the rocket's status, collecting data during flight, and logging data
1720 after flight without the need for a notebook computer on the
1721 flight line. Particularly since it is so difficult to read most
1722 notebook screens in direct sunlight, we think this will be a great
1723 thing to have. We are also working on a TeleDongle variant with
1724 Bluetooth that will work with Android phones and tablets.
1727 Because all of our work is open, both the hardware designs and the
1728 software, if you have some great idea for an addition to the current
1729 Altus Metrum family, feel free to dive in and help! Or let us know
1730 what you'd like to see that we aren't already working on, and maybe
1731 we'll get excited about it too...
1735 <ulink url="http://altusmetrum.org/">web site</ulink> for more news
1736 and information as our family of products evolves!
1741 <title>Altimeter Installation Recommendations</title>
1743 Building high-power rockets that fly safely is hard enough. Mix
1744 in some sophisticated electronics and a bunch of radio energy
1745 and oftentimes you find few perfect solutions. This chapter
1746 contains some suggestions about how to install Altus Metrum
1747 products into the rocket air-frame, including how to safely and
1748 reliably mix a variety of electronics into the same air-frame.
1751 <title>Mounting the Altimeter</title>
1753 The first consideration is to ensure that the altimeter is
1754 securely fastened to the air-frame. For TeleMetrum, we use
1755 nylon standoffs and nylon screws; they're good to at least 50G
1756 and cannot cause any electrical issues on the board. For
1757 TeleMini, we usually cut small pieces of 1/16" balsa to fit
1758 under the screw holes, and then take 2x56 nylon screws and
1759 screw them through the TeleMini mounting holes, through the
1760 balsa and into the underlying material.
1762 <orderedlist inheritnum='inherit' numeration='arabic'>
1764 Make sure TeleMetrum is aligned precisely along the axis of
1765 acceleration so that the accelerometer can accurately
1766 capture data during the flight.
1769 Watch for any metal touching components on the
1770 board. Shorting out connections on the bottom of the board
1771 can cause the altimeter to fail during flight.
1776 <title>Dealing with the Antenna</title>
1778 The antenna supplied is just a piece of solid, insulated,
1779 wire. If it gets damaged or broken, it can be easily
1780 replaced. It should be kept straight and not cut; bending or
1781 cutting it will change the resonant frequency and/or
1782 impedance, making it a less efficient radiator and thus
1783 reducing the range of the telemetry signal.
1786 Keeping metal away from the antenna will provide better range
1787 and a more even radiation pattern. In most rockets, it's not
1788 entirely possible to isolate the antenna from metal
1789 components; there are often bolts, all-thread and wires from other
1790 electronics to contend with. Just be aware that the more stuff
1791 like this around the antenna, the lower the range.
1794 Make sure the antenna is not inside a tube made or covered
1795 with conducting material. Carbon fiber is the most common
1796 culprit here -- CF is a good conductor and will effectively
1797 shield the antenna, dramatically reducing signal strength and
1798 range. Metallic flake paint is another effective shielding
1799 material which is to be avoided around any antennas.
1802 If the ebay is large enough, it can be convenient to simply
1803 mount the altimeter at one end and stretch the antenna out
1804 inside. Taping the antenna to the sled can keep it straight
1805 under acceleration. If there are metal rods, keep the
1806 antenna as far away as possible.
1809 For a shorter ebay, it's quite practical to have the antenna
1810 run through a bulkhead and into an adjacent bay. Drill a small
1811 hole in the bulkhead, pass the antenna wire through it and
1812 then seal it up with glue or clay. We've also used acrylic
1813 tubing to create a cavity for the antenna wire. This works a
1814 bit better in that the antenna is known to stay straight and
1815 not get folded by recovery components in the bay. Angle the
1816 tubing towards the side wall of the rocket and it ends up
1817 consuming very little space.
1820 If you need to place the antenna at a distance from the
1821 altimeter, you can replace the antenna with an edge-mounted
1822 SMA connector, and then run 50Ω coax from the board to the
1823 antenna. Building a remote antenna is beyond the scope of this
1828 <title>Preserving GPS Reception</title>
1830 The GPS antenna and receiver in TeleMetrum are highly
1831 sensitive and normally have no trouble tracking enough
1832 satellites to provide accurate position information for
1833 recovering the rocket. However, there are many ways to
1834 attenuate the GPS signal.
1835 <orderedlist inheritnum='inherit' numeration='arabic'>
1837 Conductive tubing or coatings. Carbon fiber and metal
1838 tubing, or metallic paint will all dramatically attenuate the
1839 GPS signal. We've never heard of anyone successfully
1840 receiving GPS from inside these materials.
1843 Metal components near the GPS patch antenna. These will
1844 de-tune the patch antenna, changing the resonant frequency
1845 away from the L1 carrier and reduce the effectiveness of the
1846 antenna. You can place as much stuff as you like beneath the
1847 antenna as that's covered with a ground plane. But, keep
1848 wires and metal out from above the patch antenna.
1854 <title>Radio Frequency Interference</title>
1856 Any altimeter will generate RFI; the digital circuits use
1857 high-frequency clocks that spray radio interference across a
1858 wide band. Altus Metrum altimeters generate intentional radio
1859 signals as well, increasing the amount of RF energy around the board.
1862 Rocketry altimeters also use precise sensors measuring air
1863 pressure and acceleration. Tiny changes in voltage can cause
1864 these sensor readings to vary by a huge amount. When the
1865 sensors start mis-reporting data, the altimeter can either
1866 fire the igniters at the wrong time, or not fire them at all.
1869 Voltages are induced when radio frequency energy is
1870 transmitted from one circuit to another. Here are things that
1871 influence the induced voltage and current:
1875 Keep wires from different circuits apart. Moving circuits
1876 further apart will reduce RFI.
1879 Avoid parallel wires from different circuits. The longer two
1880 wires run parallel to one another, the larger the amount of
1881 transferred energy. Cross wires at right angles to reduce
1885 Twist wires from the same circuits. Two wires the same
1886 distance from the transmitter will get the same amount of
1887 induced energy which will then cancel out. Any time you have
1888 a wire pair running together, twist the pair together to
1889 even out distances and reduce RFI. For altimeters, this
1890 includes battery leads, switch hookups and igniter
1894 Avoid resonant lengths. Know what frequencies are present
1895 in the environment and avoid having wire lengths near a
1896 natural resonant length. Altusmetrum products transmit on the
1897 70cm amateur band, so you should avoid lengths that are a
1898 simple ratio of that length; essentially any multiple of 1/4
1899 of the wavelength (17.5cm).
1904 <title>The Barometric Sensor</title>
1906 Altusmetrum altimeters measure altitude with a barometric
1907 sensor, essentially measuring the amount of air above the
1908 rocket to figure out how high it is. A large number of
1909 measurements are taken as the altimeter initializes itself to
1910 figure out the pad altitude. Subsequent measurements are then
1911 used to compute the height above the pad.
1914 To accurately measure atmospheric pressure, the ebay
1915 containing the altimeter must be vented outside the
1916 air-frame. The vent must be placed in a region of linear
1917 airflow, have smooth edges, and away from areas of increasing or
1918 decreasing pressure.
1921 The barometric sensor in the altimeter is quite sensitive to
1922 chemical damage from the products of APCP or BP combustion, so
1923 make sure the ebay is carefully sealed from any compartment
1924 which contains ejection charges or motors.
1928 <title>Ground Testing</title>
1930 The most important aspect of any installation is careful
1931 ground testing. Bringing an air-frame up to the LCO table which
1932 hasn't been ground tested can lead to delays or ejection
1933 charges firing on the pad, or, even worse, a recovery system
1937 Do a 'full systems' test that includes wiring up all igniters
1938 without any BP and turning on all of the electronics in flight
1939 mode. This will catch any mistakes in wiring and any residual
1940 RFI issues that might accidentally fire igniters at the wrong
1941 time. Let the air-frame sit for several minutes, checking for
1942 adequate telemetry signal strength and GPS lock. If any igniters
1943 fire unexpectedly, find and resolve the issue before loading any
1947 Ground test the ejection charges. Prepare the rocket for
1948 flight, loading ejection charges and igniters. Completely
1949 assemble the air-frame and then use the 'Fire Igniters'
1950 interface through a TeleDongle to command each charge to
1951 fire. Make sure the charge is sufficient to robustly separate
1952 the air-frame and deploy the recovery system.
1957 <title>Updating Device Firmware</title>
1959 The big concept to understand is that you have to use a
1960 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
1961 and a TeleMetrum or other TeleDongle to program the TeleDongle
1962 Due to limited memory resources in the cc1111, we don't support
1963 programming directly over USB.
1966 You may wish to begin by ensuring you have current firmware images.
1967 These are distributed as part of the AltOS software bundle that
1968 also includes the AltosUI ground station program. Newer ground
1969 station versions typically work fine with older firmware versions,
1970 so you don't need to update your devices just to try out new
1971 software features. You can always download the most recent
1972 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
1975 We recommend updating the altimeter first, before updating TeleDongle.
1978 <title>Updating TeleMetrum Firmware</title>
1979 <orderedlist inheritnum='inherit' numeration='arabic'>
1981 Find the 'programming cable' that you got as part of the starter
1982 kit, that has a red 8-pin MicroMaTch connector on one end and a
1983 red 4-pin MicroMaTch connector on the other end.
1986 Take the 2 screws out of the TeleDongle case to get access
1987 to the circuit board.
1990 Plug the 8-pin end of the programming cable to the
1991 matching connector on the TeleDongle, and the 4-pin end to the
1992 matching connector on the TeleMetrum.
1993 Note that each MicroMaTch connector has an alignment pin that
1994 goes through a hole in the PC board when you have the cable
1998 Attach a battery to the TeleMetrum board.
2001 Plug the TeleDongle into your computer's USB port, and power
2005 Run AltosUI, and select 'Flash Image' from the File menu.
2008 Pick the TeleDongle device from the list, identifying it as the
2012 Select the image you want put on the TeleMetrum, which should have a
2013 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
2014 in the default directory, if not you may have to poke around
2015 your system to find it.
2018 Make sure the configuration parameters are reasonable
2019 looking. If the serial number and/or RF configuration
2020 values aren't right, you'll need to change them.
2023 Hit the 'OK' button and the software should proceed to flash
2024 the TeleMetrum with new firmware, showing a progress bar.
2027 Confirm that the TeleMetrum board seems to have updated OK, which you
2028 can do by plugging in to it over USB and using a terminal program
2029 to connect to the board and issue the 'v' command to check
2033 If something goes wrong, give it another try.
2038 <title>Updating TeleMini Firmware</title>
2039 <orderedlist inheritnum='inherit' numeration='arabic'>
2041 You'll need a special 'programming cable' to reprogram the
2042 TeleMini. It's available on the Altus Metrum web store, or
2043 you can make your own using an 8-pin MicroMaTch connector on
2044 one end and a set of four pins on the other.
2047 Take the 2 screws out of the TeleDongle case to get access
2048 to the circuit board.
2051 Plug the 8-pin end of the programming cable to the matching
2052 connector on the TeleDongle, and the 4-pins into the holes
2053 in the TeleMini circuit board. Note that the MicroMaTch
2054 connector has an alignment pin that goes through a hole in
2055 the PC board when you have the cable oriented correctly, and
2056 that pin 1 on the TeleMini board is marked with a square pad
2057 while the other pins have round pads.
2060 Attach a battery to the TeleMini board.
2063 Plug the TeleDongle into your computer's USB port, and power
2067 Run AltosUI, and select 'Flash Image' from the File menu.
2070 Pick the TeleDongle device from the list, identifying it as the
2074 Select the image you want put on the TeleMini, which should have a
2075 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
2076 in the default directory, if not you may have to poke around
2077 your system to find it.
2080 Make sure the configuration parameters are reasonable
2081 looking. If the serial number and/or RF configuration
2082 values aren't right, you'll need to change them.
2085 Hit the 'OK' button and the software should proceed to flash
2086 the TeleMini with new firmware, showing a progress bar.
2089 Confirm that the TeleMini board seems to have updated OK, which you
2090 can do by configuring it over the radio link through the TeleDongle, or
2091 letting it come up in "flight" mode and listening for telemetry.
2094 If something goes wrong, give it another try.
2099 <title>Updating TeleDongle Firmware</title>
2101 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
2102 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
2104 <orderedlist inheritnum='inherit' numeration='arabic'>
2106 Find the 'programming cable' that you got as part of the starter
2107 kit, that has a red 8-pin MicroMaTch connector on one end and a
2108 red 4-pin MicroMaTch connector on the other end.
2111 Find the USB cable that you got as part of the starter kit, and
2112 plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
2115 Take the 2 screws out of the TeleDongle case to get access
2116 to the circuit board.
2119 Plug the 8-pin end of the programming cable to the
2120 matching connector on the programmer, and the 4-pin end to the
2121 matching connector on the TeleDongle.
2122 Note that each MicroMaTch connector has an alignment pin that
2123 goes through a hole in the PC board when you have the cable
2127 Attach a battery to the TeleMetrum board if you're using one.
2130 Plug both the programmer and the TeleDongle into your computer's USB
2131 ports, and power up the programmer.
2134 Run AltosUI, and select 'Flash Image' from the File menu.
2137 Pick the programmer device from the list, identifying it as the
2141 Select the image you want put on the TeleDongle, which should have a
2142 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
2143 in the default directory, if not you may have to poke around
2144 your system to find it.
2147 Make sure the configuration parameters are reasonable
2148 looking. If the serial number and/or RF configuration
2149 values aren't right, you'll need to change them. The TeleDongle
2150 serial number is on the "bottom" of the circuit board, and can
2151 usually be read through the translucent blue plastic case without
2152 needing to remove the board from the case.
2155 Hit the 'OK' button and the software should proceed to flash
2156 the TeleDongle with new firmware, showing a progress bar.
2159 Confirm that the TeleDongle board seems to have updated OK, which you
2160 can do by plugging in to it over USB and using a terminal program
2161 to connect to the board and issue the 'v' command to check
2162 the version, etc. Once you're happy, remove the programming cable
2163 and put the cover back on the TeleDongle.
2166 If something goes wrong, give it another try.
2170 Be careful removing the programming cable from the locking 8-pin
2171 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
2172 screwdriver or knife blade to gently pry the locking ears out
2173 slightly to extract the connector. We used a locking connector on
2174 TeleMetrum to help ensure that the cabling to companion boards
2175 used in a rocket don't ever come loose accidentally in flight.
2180 <title>Hardware Specifications</title>
2182 <title>TeleMetrum Specifications</title>
2186 Recording altimeter for model rocketry.
2191 Supports dual deployment (can fire 2 ejection charges).
2196 70cm ham-band transceiver for telemetry down-link.
2201 Barometric pressure sensor good to 45k feet MSL.
2206 1-axis high-g accelerometer for motor characterization, capable of
2207 +/- 50g using default part.
2212 On-board, integrated GPS receiver with 5Hz update rate capability.
2217 On-board 1 megabyte non-volatile memory for flight data storage.
2222 USB interface for battery charging, configuration, and data recovery.
2227 Fully integrated support for Li-Po rechargeable batteries.
2232 Uses Li-Po to fire e-matches, can be modified to support
2233 optional separate pyro battery if needed.
2238 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
2244 <title>TeleMini Specifications</title>
2248 Recording altimeter for model rocketry.
2253 Supports dual deployment (can fire 2 ejection charges).
2258 70cm ham-band transceiver for telemetry down-link.
2263 Barometric pressure sensor good to 45k feet MSL.
2268 On-board 5 kilobyte non-volatile memory for flight data storage.
2273 RF interface for configuration, and data recovery.
2278 Support for Li-Po rechargeable batteries, using an external charger.
2283 Uses Li-Po to fire e-matches, can be modified to support
2284 optional separate pyro battery if needed.
2289 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
2298 TeleMetrum seems to shut off when disconnected from the
2299 computer. Make sure the battery is adequately charged. Remember the
2300 unit will pull more power than the USB port can deliver before the
2301 GPS enters "locked" mode. The battery charges best when TeleMetrum
2305 It's impossible to stop the TeleDongle when it's in "p" mode, I have
2306 to unplug the USB cable? Make sure you have tried to "escape out" of
2307 this mode. If this doesn't work the reboot procedure for the
2308 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
2309 outgoing buffer IF your "escape out" ('~~') does not work.
2310 At this point using either 'ao-view' (or possibly
2311 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
2315 The amber LED (on the TeleMetrum) lights up when both
2316 battery and USB are connected. Does this mean it's charging?
2317 Yes, the yellow LED indicates the charging at the 'regular' rate.
2318 If the led is out but the unit is still plugged into a USB port,
2319 then the battery is being charged at a 'trickle' rate.
2322 There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
2323 That's the "pad" mode. Weak batteries might be the problem.
2324 It is also possible that the TeleMetrum is horizontal and the output
2325 is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
2326 it received a command packet which would have left it in "pad" mode.
2329 How do I save flight data?
2330 Live telemetry is written to file(s) whenever AltosUI is connected
2331 to the TeleDongle. The file area defaults to ~/TeleMetrum
2332 but is easily changed using the menus in AltosUI. The files that
2333 are written end in '.telem'. The after-flight
2334 data-dumped files will end in .eeprom and represent continuous data
2335 unlike the .telem files that are subject to losses
2336 along the RF data path.
2337 See the above instructions on what and how to save the eeprom stored
2338 data after physically retrieving your altimeter. Make sure to save
2339 the on-board data after each flight; while the TeleMetrum can store
2340 multiple flights, you never know when you'll lose the altimeter...
2344 <title>Notes for Older Software</title>
2347 Before AltosUI was written, using Altus Metrum devices required
2348 some finesse with the Linux command line. There was a limited
2349 GUI tool, ao-view, which provided functionality similar to the
2350 Monitor Flight window in AltosUI, but everything else was a
2351 fairly 80's experience. This appendix includes documentation for
2352 using that software.
2356 Both TeleMetrum and TeleDongle can be directly communicated
2357 with using USB ports. The first thing you should try after getting
2358 both units plugged into to your computer's USB port(s) is to run
2359 'ao-list' from a terminal-window to see what port-device-name each
2360 device has been assigned by the operating system.
2361 You will need this information to access the devices via their
2362 respective on-board firmware and data using other command line
2363 programs in the AltOS software suite.
2366 TeleMini can be communicated with through a TeleDongle device
2367 over the radio link. When first booted, TeleMini listens for a
2368 TeleDongle device and if it receives a packet, it goes into
2369 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
2370 launched. The easiest way to get it talking is to start the
2371 communication link on the TeleDongle and the power up the
2375 To access the device's firmware for configuration you need a terminal
2376 program such as you would use to talk to a modem. The software
2377 authors prefer using the program 'cu' which comes from the UUCP package
2378 on most Unix-like systems such as Linux. An example command line for
2379 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
2380 indicated from running the
2381 ao-list program. Another reasonable terminal program for Linux is
2382 'cutecom'. The default 'escape'
2383 character used by CU (i.e. the character you use to
2384 issue commands to cu itself instead of sending the command as input
2385 to the connected device) is a '~'. You will need this for use in
2386 only two different ways during normal operations. First is to exit
2387 the program by sending a '~.' which is called a 'escape-disconnect'
2388 and allows you to close-out from 'cu'. The
2389 second use will be outlined later.
2392 All of the Altus Metrum devices share the concept of a two level
2393 command set in their firmware.
2394 The first layer has several single letter commands. Once
2395 you are using 'cu' (or 'cutecom') sending (typing) a '?'
2396 returns a full list of these
2397 commands. The second level are configuration sub-commands accessed
2398 using the 'c' command, for
2399 instance typing 'c?' will give you this second level of commands
2400 (all of which require the
2401 letter 'c' to access). Please note that most configuration options
2402 are stored only in Flash memory; TeleDongle doesn't provide any storage
2403 for these options and so they'll all be lost when you unplug it.
2406 Try setting these configuration ('c' or second level menu) values. A good
2407 place to start is by setting your call sign. By default, the boards
2408 use 'N0CALL' which is cute, but not exactly legal!
2409 Spend a few minutes getting comfortable with the units, their
2410 firmware, and 'cu' (or possibly 'cutecom').
2411 For instance, try to send
2412 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
2413 Verify you can connect and disconnect from the units while in your
2414 terminal program by sending the escape-disconnect mentioned above.
2417 To set the radio frequency, use the 'c R' command to specify the
2418 radio transceiver configuration parameter. This parameter is computed
2419 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
2420 the standard calibration reference frequency, 'S', (normally 434.550MHz):
2424 Round the result to the nearest integer value.
2425 As with all 'c' sub-commands, follow this with a 'c w' to write the
2426 change to the parameter block in the on-board flash on
2427 your altimeter board if you want the change to stay in place across reboots.
2430 To set the apogee delay, use the 'c d' command.
2431 As with all 'c' sub-commands, follow this with a 'c w' to write the
2432 change to the parameter block in the on-board DataFlash chip.
2435 To set the main deployment altitude, use the 'c m' command.
2436 As with all 'c' sub-commands, follow this with a 'c w' to write the
2437 change to the parameter block in the on-board DataFlash chip.
2440 To calibrate the radio frequency, connect the UHF antenna port to a
2441 frequency counter, set the board to 434.550MHz, and use the 'C'
2442 command to generate a CW carrier. Wait for the transmitter temperature
2443 to stabilize and the frequency to settle down.
2444 Then, divide 434.550 MHz by the
2445 measured frequency and multiply by the current radio cal value show
2446 in the 'c s' command. For an unprogrammed board, the default value
2447 is 1186611. Take the resulting integer and program it using the 'c f'
2448 command. Testing with the 'C' command again should show a carrier
2449 within a few tens of Hertz of the intended frequency.
2450 As with all 'c' sub-commands, follow this with a 'c w' to write the
2451 change to the parameter block in the on-board DataFlash chip.
2454 Note that the 'reboot' command, which is very useful on the altimeters,
2455 will likely just cause problems with the dongle. The *correct* way
2456 to reset the dongle is just to unplug and re-plug it.
2459 A fun thing to do at the launch site and something you can do while
2460 learning how to use these units is to play with the radio link access
2461 between an altimeter and the TeleDongle. Be aware that you *must* create
2462 some physical separation between the devices, otherwise the link will
2463 not function due to signal overload in the receivers in each device.
2466 Now might be a good time to take a break and read the rest of this
2467 manual, particularly about the two "modes" that the altimeters
2468 can be placed in. TeleMetrum uses the position of the device when booting
2469 up will determine whether the unit is in "pad" or "idle" mode. TeleMini
2470 enters "idle" mode when it receives a command packet within the first 5 seconds
2471 of being powered up, otherwise it enters "pad" mode.
2474 You can access an altimeter in idle mode from the TeleDongle's USB
2475 connection using the radio link
2476 by issuing a 'p' command to the TeleDongle. Practice connecting and
2477 disconnecting ('~~' while using 'cu') from the altimeter. If
2478 you cannot escape out of the "p" command, (by using a '~~' when in
2479 CU) then it is likely that your kernel has issues. Try a newer version.
2482 Using this radio link allows you to configure the altimeter, test
2483 fire e-matches and igniters from the flight line, check pyro-match
2484 continuity and so forth. You can leave the unit turned on while it
2485 is in 'idle mode' and then place the
2486 rocket vertically on the launch pad, walk away and then issue a
2487 reboot command. The altimeter will reboot and start sending data
2488 having changed to the "pad" mode. If the TeleDongle is not receiving
2489 this data, you can disconnect 'cu' from the TeleDongle using the
2490 procedures mentioned above and THEN connect to the TeleDongle from
2491 inside 'ao-view'. If this doesn't work, disconnect from the
2492 TeleDongle, unplug it, and try again after plugging it back in.
2495 In order to reduce the chance of accidental firing of pyrotechnic
2496 charges, the command to fire a charge is intentionally somewhat
2497 difficult to type, and the built-in help is slightly cryptic to
2498 prevent accidental echoing of characters from the help text back at
2499 the board from firing a charge. The command to fire the apogee
2500 drogue charge is 'i DoIt drogue' and the command to fire the main
2501 charge is 'i DoIt main'.
2504 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
2505 and 'ao-view' will both auditorily announce and visually indicate
2507 Now you can launch knowing that you have a good data path and
2508 good satellite lock for flight data and recovery. Remember
2509 you MUST tell ao-view to connect to the TeleDongle explicitly in
2510 order for ao-view to be able to receive data.
2513 The altimeters provide RDF (radio direction finding) tones on
2514 the pad, during descent and after landing. These can be used to
2515 locate the rocket using a directional antenna; the signal
2516 strength providing an indication of the direction from receiver to rocket.
2519 TeleMetrum also provides GPS tracking data, which can further simplify
2520 locating the rocket once it has landed. (The last good GPS data
2521 received before touch-down will be on the data screen of 'ao-view'.)
2524 Once you have recovered the rocket you can download the eeprom
2525 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
2526 either a USB cable or over the radio link using TeleDongle.
2527 And by following the man page for 'ao-postflight' you can create
2528 various data output reports, graphs, and even KML data to see the
2529 flight trajectory in Google-earth. (Moving the viewing angle making
2530 sure to connect the yellow lines while in Google-earth is the proper
2534 As for ao-view.... some things are in the menu but don't do anything
2535 very useful. The developers have stopped working on ao-view to focus
2536 on a new, cross-platform ground station program. So ao-view may or
2537 may not be updated in the future. Mostly you just use
2538 the Log and Device menus. It has a wonderful display of the incoming
2539 flight data and I am sure you will enjoy what it has to say to you
2540 once you enable the voice output!
2544 <title>Drill Templates</title>
2546 These images, when printed, provide precise templates for the
2547 mounting holes in Altus Metrum flight computers
2550 <title>TeleMetrum template</title>
2552 TeleMetrum has overall dimensions of 1.000 x 2.750 inches, and the
2553 mounting holes are sized for use with 4-40 or M3 screws.
2555 <mediaobject id="TeleMetrumTemplate">
2557 <imagedata format="SVG" fileref="telemetrum.svg"/>
2562 <title>TeleMini template</title>
2564 TeleMini has overall dimensions of 0.500 x 1.500 inches, and the
2565 mounting holes are sized for use with 2-56 or M2 screws.
2567 <mediaobject id="TeleMiniTemplate">
2569 <imagedata format="SVG" fileref="telemini.svg"/>
2575 <title>Calibration</title>
2577 There are only two calibrations required for a TeleMetrum board, and
2578 only one for TeleDongle and TeleMini. All boards are shipped from
2579 the factory pre-calibrated, but the procedures are documented here
2580 in case they are ever needed. Re-calibration is not supported by
2581 AltosUI, you must connect to the board with a serial terminal program
2582 and interact directly with the on-board command interpreter to effect
2586 <title>Radio Frequency</title>
2588 The radio frequency is synthesized from a clock based on the 48 MHz
2589 crystal on the board. The actual frequency of this oscillator
2590 must be measured to generate a calibration constant. While our
2592 bandwidth is wide enough to allow boards to communicate even when
2593 their oscillators are not on exactly the same frequency, performance
2594 is best when they are closely matched.
2595 Radio frequency calibration requires a calibrated frequency counter.
2596 Fortunately, once set, the variation in frequency due to aging and
2597 temperature changes is small enough that re-calibration by customers
2598 should generally not be required.
2601 To calibrate the radio frequency, connect the UHF antenna port to a
2602 frequency counter, set the board to 434.550MHz, and use the 'C'
2603 command in the on-board command interpreter to generate a CW
2604 carrier. For TeleMetrum, this is best done over USB. For TeleMini,
2605 note that the only way to escape the 'C' command is via power cycle
2606 since the board will no longer be listening for commands once it
2607 starts generating a CW carrier.
2610 Wait for the transmitter temperature to stabilize and the frequency
2611 to settle down. Then, divide 434.550 MHz by the
2612 measured frequency and multiply by the current radio cal value show
2613 in the 'c s' command. For an unprogrammed board, the default value
2614 is 1186611. Take the resulting integer and program it using the 'c f'
2615 command. Testing with the 'C' command again should show a carrier
2616 within a few tens of Hertz of the intended frequency.
2617 As with all 'c' sub-commands, follow this with a 'c w' to write the
2618 change to the parameter block in the on-board DataFlash chip.
2621 Note that any time you re-do the radio frequency calibration, the
2622 radio frequency is reset to the default 434.550 Mhz. If you want
2623 to use another frequency, you will have to set that again after
2624 calibration is completed.
2628 <title>TeleMetrum Accelerometer</title>
2630 The TeleMetrum accelerometer we use has its own 5 volt power
2632 the output must be passed through a resistive voltage divider to match
2633 the input of our 3.3 volt ADC. This means that unlike the barometric
2634 sensor, the output of the acceleration sensor is not ratio-metric to
2635 the ADC converter, and calibration is required. Explicitly
2636 calibrating the accelerometers also allows us to load any device
2637 from a Freescale family that includes at least +/- 40g, 50g, 100g,
2638 and 200g parts. Using gravity,
2639 a simple 2-point calibration yields acceptable results capturing both
2640 the different sensitivities and ranges of the different accelerometer
2641 parts and any variation in power supply voltages or resistor values
2642 in the divider network.
2645 To calibrate the acceleration sensor, use the 'c a 0' command. You
2646 will be prompted to orient the board vertically with the UHF antenna
2647 up and press a key, then to orient the board vertically with the
2648 UHF antenna down and press a key. Note that the accuracy of this
2649 calibration depends primarily on how perfectly vertical and still
2650 the board is held during the cal process. As with all 'c'
2651 sub-commands, follow this with a 'c w' to write the
2652 change to the parameter block in the on-board DataFlash chip.
2655 The +1g and -1g calibration points are included in each telemetry
2656 frame and are part of the header stored in onboard flash to be
2657 downloaded after flight. We always store and return raw ADC
2658 samples for each sensor... so nothing is permanently "lost" or
2659 "damaged" if the calibration is poor.
2662 In the unlikely event an accel cal goes badly, it is possible
2663 that TeleMetrum may always come up in 'pad mode' and as such not be
2664 listening to either the USB or radio link. If that happens,
2665 there is a special hook in the firmware to force the board back
2666 in to 'idle mode' so you can re-do the cal. To use this hook, you
2667 just need to ground the SPI clock pin at power-on. This pin is
2668 available as pin 2 on the 8-pin companion connector, and pin 1 is
2669 ground. So either carefully install a fine-gauge wire jumper
2670 between the two pins closest to the index hole end of the 8-pin
2671 connector, or plug in the programming cable to the 8-pin connector
2672 and use a small screwdriver or similar to short the two pins closest
2673 to the index post on the 4-pin end of the programming cable, and
2674 power up the board. It should come up in 'idle mode' (two beeps),
2680 xmlns:xi="http://www.w3.org/2001/XInclude">
2681 <title>Release Notes</title>
2682 <simplesect><title>Version 1.1.1</title><xi:include href="release-notes-1.1.1.xsl" xpointer="xpointer(/article/*)"/></simplesect>
2683 <simplesect><title>Version 1.1</title><xi:include href="release-notes-1.1.xsl" xpointer="xpointer(/article/*)"/></simplesect>
2684 <simplesect><title>Version 1.0.1</title><xi:include href="release-notes-1.0.1.xsl" xpointer="xpointer(/article/*)"/></simplesect>
2685 <simplesect><title>Version 0.9.2</title><xi:include href="release-notes-0.9.2.xsl" xpointer="xpointer(/article/*)"/></simplesect>
2686 <simplesect><title>Version 0.9</title><xi:include href="release-notes-0.9.xsl" xpointer="xpointer(/article/*)"/></simplesect>
2687 <simplesect><title>Version 0.8</title><xi:include href="release-notes-0.8.xsl" xpointer="xpointer(/article/*)"/></simplesect>
2688 <simplesect><title>Version 0.7.1</title><xi:include href="release-notes-0.7.1.xsl" xpointer="xpointer(/article/*)"/></simplesect>
2692 <!-- LocalWords: Altusmetrum
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