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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</revnumber>
40 <date>13 September 2012</date>
42 Updated for software version 1.1. Version 1.1 has new
43 features but is otherwise compatible with version 1.0.
47 <revnumber>1.0</revnumber>
48 <date>24 August 2011</date>
50 Updated for software version 1.0. Note that 1.0 represents a
51 telemetry format change, meaning both ends of a link
52 (TeleMetrum/TeleMini and TeleDongle) must be updated or
53 communications will fail.
57 <revnumber>0.9</revnumber>
58 <date>18 January 2011</date>
60 Updated for software version 0.9. Note that 0.9 represents a
61 telemetry format change, meaning both ends of a link (TeleMetrum and
62 TeleDongle) must be updated or communications will fail.
66 <revnumber>0.8</revnumber>
67 <date>24 November 2010</date>
68 <revremark>Updated for software version 0.8 </revremark>
74 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing "The
75 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
76 Kit" which formed the basis of the original Getting Started chapter
77 in this manual. Bob was one of our first customers for a production
78 TeleMetrum, and his continued enthusiasm and contributions
79 are immensely gratifying and highly appreciated!
82 And thanks to Anthony (AJ) Towns for major contributions including
83 the AltosUI graphing and site map code and associated documentation.
84 Free software means that our customers and friends can become our
85 collaborators, and we certainly appreciate this level of
89 Have fun using these products, and we hope to meet all of you
90 out on the rocket flight line somewhere.
93 NAR #87103, TRA #12201
96 NAR #88757, TRA #12200
101 <title>Introduction and Overview</title>
103 Welcome to the Altus Metrum community! Our circuits and software reflect
104 our passion for both hobby rocketry and Free Software. We hope their
105 capabilities and performance will delight you in every way, but by
106 releasing all of our hardware and software designs under open licenses,
107 we also hope to empower you to take as active a role in our collective
111 The first device created for our community was TeleMetrum, a dual
112 deploy altimeter with fully integrated GPS and radio telemetry
113 as standard features, and a "companion interface" that will
114 support optional capabilities in the future.
117 The newest device is TeleMini, a dual deploy altimeter with
118 radio telemetry and radio direction finding. This device is only
119 13mm by 38mm (½ inch by 1½ inches) and can fit easily in an 18mm
123 Complementing TeleMetrum and TeleMini is TeleDongle, a USB to RF
124 interface for communicating with the altimeters. Combined with your
125 choice of antenna and
126 notebook computer, TeleDongle and our associated user interface software
127 form a complete ground station capable of logging and displaying in-flight
128 telemetry, aiding rocket recovery, then processing and archiving flight
129 data for analysis and review.
132 More products will be added to the Altus Metrum family over time, and
133 we currently envision that this will be a single, comprehensive manual
134 for the entire product family.
138 <title>Getting Started</title>
140 The first thing to do after you check the inventory of parts in your
141 "starter kit" is to charge the battery.
144 The TeleMetrum battery can be charged by plugging it into the
145 corresponding socket of the TeleMetrum and then using the USB A to
147 cable to plug the TeleMetrum into your computer's USB socket. The
148 TeleMetrum circuitry will charge the battery whenever it is plugged
149 in, because the TeleMetrum's on-off switch does NOT control the
153 When the GPS chip is initially searching for
154 satellites, TeleMetrum will consume more current than it can pull
155 from the USB port, so the battery must be attached in order to get
156 satellite lock. Once GPS is locked, the current consumption goes back
157 down enough to enable charging while
158 running. So it's a good idea to fully charge the battery as your
159 first item of business so there is no issue getting and maintaining
160 satellite lock. The yellow charge indicator led will go out when the
161 battery is nearly full and the charger goes to trickle charge. It
162 can take several hours to fully recharge a deeply discharged battery.
165 The TeleMini battery can be charged by disconnecting it from the
166 TeleMini board and plugging it into a standalone battery charger
167 board, and connecting that via a USB cable to a laptop or other USB
171 The other active device in the starter kit is the TeleDongle USB to
172 RF interface. If you plug it in to your Mac or Linux computer it should
173 "just work", showing up as a serial port device. Windows systems need
174 driver information that is part of the AltOS download to know that the
175 existing USB modem driver will work. We therefore recommend installing
176 our software before plugging in TeleDongle if you are using a Windows
177 computer. If you are using Linux and are having problems, try moving
178 to a fresher kernel (2.6.33 or newer), as the USB serial driver had
179 ugly bugs in some earlier versions.
182 Next you should obtain and install the AltOS software. These include
183 the AltosUI ground station program, current firmware images for
184 TeleMetrum, TeleMini and TeleDongle, and a number of standalone
185 utilities that are rarely needed. Pre-built binary packages are
186 available for Linux, Microsoft Windows, and recent MacOSX versions.
187 Full source code and build instructions are also available.
188 The latest version may always be downloaded from
189 <ulink url="http://altusmetrum.org/AltOS"/>.
193 <title>Handling Precautions</title>
195 All Altus Metrum products are sophisticated electronic devices.
196 When handled gently and properly installed in an air-frame, they
197 will deliver impressive results. However, as with all electronic
198 devices, there are some precautions you must take.
201 The Lithium Polymer rechargeable batteries have an
202 extraordinary power density. This is great because we can fly with
203 much less battery mass than if we used alkaline batteries or previous
204 generation rechargeable batteries... but if they are punctured
205 or their leads are allowed to short, they can and will release their
207 Thus we recommend that you take some care when handling our batteries
208 and consider giving them some extra protection in your air-frame. We
209 often wrap them in suitable scraps of closed-cell packing foam before
210 strapping them down, for example.
213 The barometric sensors used on both TeleMetrum and TeleMini are
214 sensitive to sunlight. In normal TeleMetrum mounting situations, it
215 and all of the other surface mount components
216 are "down" towards whatever the underlying mounting surface is, so
217 this is not normally a problem. Please consider this, though, when
218 designing an installation, for example, in an air-frame with a
219 see-through plastic payload bay. It is particularly important to
220 consider this with TeleMini, both because the baro sensor is on the
221 "top" of the board, and because many model rockets with payload bays
222 use clear plastic for the payload bay! Replacing these with an opaque
223 cardboard tube, painting them, or wrapping them with a layer of masking
224 tape are all reasonable approaches to keep the sensor out of direct
228 The barometric sensor sampling port must be able to "breathe",
229 both by not being covered by foam or tape or other materials that might
230 directly block the hole on the top of the sensor, and also by having a
231 suitable static vent to outside air.
234 As with all other rocketry electronics, Altus Metrum altimeters must
235 be protected from exposure to corrosive motor exhaust and ejection
240 <title>Hardware Overview</title>
242 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
243 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
244 small in diameter may require some creativity in mounting and wiring
245 to succeed! The presence of an accelerometer means TeleMetrum should
246 be aligned along the flight axis of the airframe, and by default the 1/4
247 wave UHF wire antenna should be on the nose-cone end of the board. The
248 antenna wire is about 7 inches long, and wiring for a power switch and
249 the e-matches for apogee and main ejection charges depart from the
250 fin can end of the board, meaning an ideal "simple" avionics
251 bay for TeleMetrum should have at least 10 inches of interior length.
254 TeleMini is a 0.5 inch by 1.5 inch circuit board. It was designed to
255 fit inside an 18mm air-frame tube, but using it in a tube that
256 small in diameter may require some creativity in mounting and wiring
257 to succeed! Since there is no accelerometer, TeleMini can be mounted
258 in any convenient orientation. The default 1/4
259 wave UHF wire antenna attached to the center of one end of
260 the board is about 7 inches long, and wiring for a power switch and
261 the e-matches for apogee and main ejection charges depart from the
262 other end of the board, meaning an ideal "simple" avionics
263 bay for TeleMini should have at least 9 inches of interior length.
266 A typical TeleMetrum or TeleMini installation involves attaching
267 only a suitable Lithium Polymer battery, a single pole switch for
268 power on/off, and two pairs of wires connecting e-matches for the
269 apogee and main ejection charges. All Altus Metrum products are
270 designed for use with single-cell batteries with 3.7 volts nominal.
273 By default, we use the unregulated output of the Li-Po battery directly
274 to fire ejection charges. This works marvelously with standard
275 low-current e-matches like the J-Tek from MJG Technologies, and with
276 Quest Q2G2 igniters. However, if you want or need to use a separate
277 pyro battery, check out the "External Pyro Battery" section in this
278 manual for instructions on how to wire that up. The altimeters are
279 designed to work with an external pyro battery of no more than 15 volts.
282 Ejection charges are wired directly to the screw terminal block
283 at the aft end of the altimeter. You'll need a very small straight
284 blade screwdriver for these screws, such as you might find in a
285 jeweler's screwdriver set.
288 TeleMetrum also uses the screw terminal block for the power
289 switch leads. On TeleMini, the power switch leads are soldered
290 directly to the board and can be connected directly to a switch.
293 For most air-frames, the integrated antennas are more than
294 adequate. However, if you are installing in a carbon-fiber or
295 metal electronics bay which is opaque to RF signals, you may need to
296 use off-board external antennas instead. In this case, you can
297 order an altimeter with an SMA connector for the UHF antenna
298 connection, and, on TeleMetrum, you can unplug the integrated GPS
299 antenna and select an appropriate off-board GPS antenna with
300 cable terminating in a U.FL connector.
304 <title>System Operation</title>
306 <title>Firmware Modes </title>
308 The AltOS firmware build for the altimeters has two
309 fundamental modes, "idle" and "flight". Which of these modes
310 the firmware operates in is determined at start up time. For
311 TeleMetrum, the mode is controlled by the orientation of the
312 rocket (well, actually the board, of course...) at the time
313 power is switched on. If the rocket is "nose up", then
314 TeleMetrum assumes it's on a rail or rod being prepared for
315 launch, so the firmware chooses flight mode. However, if the
316 rocket is more or less horizontal, the firmware instead enters
317 idle mode. Since TeleMini doesn't have an accelerometer we can
318 use to determine orientation, "idle" mode is selected when the
319 board receives a command packet within the first five seconds
320 of operation; if no packet is received, the board enters
324 At power on, you will hear three beeps or see three flashes
325 ("S" in Morse code for start up) and then a pause while
326 the altimeter completes initialization and self test, and decides
327 which mode to enter next.
330 In flight or "pad" mode, the altimeter engages the flight
331 state machine, goes into transmit-only mode to
332 send telemetry, and waits for launch to be detected.
333 Flight mode is indicated by an "di-dah-dah-dit" ("P" for pad)
334 on the beeper or lights, followed by beeps or flashes
335 indicating the state of the pyrotechnic igniter continuity.
336 One beep/flash indicates apogee continuity, two beeps/flashes
337 indicate main continuity, three beeps/flashes indicate both
338 apogee and main continuity, and one longer "brap" sound or
339 rapidly alternating lights indicates no continuity. For a
340 dual deploy flight, make sure you're getting three beeps or
341 flashes before launching! For apogee-only or motor eject
342 flights, do what makes sense.
345 If idle mode is entered, you will hear an audible "di-dit" or see
346 two short flashes ("I" for idle), and the flight state machine is
347 disengaged, thus no ejection charges will fire. The altimeters also
348 listen for the radio link when in idle mode for requests sent via
349 TeleDongle. Commands can be issued to a TeleMetrum in idle mode
351 USB or the radio link equivalently. TeleMini only has the radio link.
352 Idle mode is useful for configuring the altimeter, for extracting data
353 from the on-board storage chip after flight, and for ground testing
357 One "neat trick" of particular value when TeleMetrum is used with
358 very large air-frames, is that you can power the board up while the
359 rocket is horizontal, such that it comes up in idle mode. Then you can
360 raise the air-frame to launch position, and issue a 'reset' command
361 via TeleDongle over the radio link to cause the altimeter to reboot and
362 come up in flight mode. This is much safer than standing on the top
363 step of a rickety step-ladder or hanging off the side of a launch
364 tower with a screw-driver trying to turn on your avionics before
371 TeleMetrum includes a complete GPS receiver. A complete explanation
372 of how GPS works is beyond the scope of this manual, but the bottom
373 line is that the TeleMetrum GPS receiver needs to lock onto at least
374 four satellites to obtain a solid 3 dimensional position fix and know
378 TeleMetrum provides backup power to the GPS chip any time a
379 battery is connected. This allows the receiver to "warm start" on
380 the launch rail much faster than if every power-on were a GPS
381 "cold start". In typical operations, powering up TeleMetrum
382 on the flight line in idle mode while performing final air-frame
383 preparation will be sufficient to allow the GPS receiver to cold
384 start and acquire lock. Then the board can be powered down during
385 RSO review and installation on a launch rod or rail. When the board
386 is turned back on, the GPS system should lock very quickly, typically
387 long before igniter installation and return to the flight line are
392 <title>Controlling An Altimeter Over The Radio Link</title>
394 One of the unique features of the Altus Metrum system is
395 the ability to create a two way command link between TeleDongle
396 and an altimeter using the digital radio transceivers built into
397 each device. This allows you to interact with the altimeter from
398 afar, as if it were directly connected to the computer.
401 Any operation which can be performed with TeleMetrum can
402 either be done with TeleMetrum directly connected to the
403 computer via the USB cable, or through the radio
404 link. TeleMini doesn't provide a USB connector and so it is
405 always communicated with over radio. Select the appropriate
406 TeleDongle device when the list of devices is presented and
407 AltosUI will interact with an altimeter over the radio link.
410 One oddity in the current interface is how AltosUI selects the
411 frequency for radio communications. Instead of providing
412 an interface to specifically configure the frequency, it uses
413 whatever frequency was most recently selected for the target
414 TeleDongle device in Monitor Flight mode. If you haven't ever
415 used that mode with the TeleDongle in question, select the
416 Monitor Flight button from the top level UI, and pick the
417 appropriate TeleDongle device. Once the flight monitoring
418 window is open, select the desired frequency and then close it
419 down again. All radio communications will now use that frequency.
424 Save Flight Data—Recover flight data from the rocket without
430 Configure altimeter apogee delays or main deploy heights
431 to respond to changing launch conditions. You can also
432 'reboot' the altimeter. Use this to remotely enable the
433 flight computer by turning TeleMetrum on in "idle" mode,
434 then once the air-frame is oriented for launch, you can
435 reboot the altimeter and have it restart in pad mode
436 without having to climb the scary ladder.
441 Fire Igniters—Test your deployment charges without snaking
442 wires out through holes in the air-frame. Simply assembly the
443 rocket as if for flight with the apogee and main charges
444 loaded, then remotely command the altimeter to fire the
450 Operation over the radio link for configuring an altimeter, ground
451 testing igniters, and so forth uses the same RF frequencies as flight
452 telemetry. To configure the desired TeleDongle frequency, select
453 the monitor flight tab, then use the frequency selector and
454 close the window before performing other desired radio operations.
457 TeleMetrum only enables radio commanding in 'idle' mode, so
458 make sure you have TeleMetrum lying horizontally when you turn
459 it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
460 flight, and will not be listening for command packets from TeleDongle.
463 TeleMini listens for a command packet for five seconds after
464 first being turned on, if it doesn't hear anything, it enters
465 'pad' mode, ready for flight and will no longer listen for
466 command packets. The easiest way to connect to TeleMini is to
467 initiate the command and select the TeleDongle device. At this
468 point, the TeleDongle will be attempting to communicate with
469 the TeleMini. Now turn TeleMini on, and it should immediately
470 start communicating with the TeleDongle and the desired
471 operation can be performed.
474 You can monitor the operation of the radio link by watching the
475 lights on the devices. The red LED will flash each time a packet
476 is tramsitted, while the green LED will light up on TeleDongle when
477 it is waiting to receive a packet from the altimeter.
481 <title>Ground Testing </title>
483 An important aspect of preparing a rocket using electronic deployment
484 for flight is ground testing the recovery system. Thanks
485 to the bi-directional radio link central to the Altus Metrum system,
486 this can be accomplished in a TeleMetrum or TeleMini equipped rocket
487 with less work than you may be accustomed to with other systems. It
491 Just prep the rocket for flight, then power up the altimeter
492 in "idle" mode (placing air-frame horizontal for TeleMetrum or
493 selected the Configure Altimeter tab for TeleMini). This will cause
494 the firmware to go into "idle" mode, in which the normal flight
495 state machine is disabled and charges will not fire without
496 manual command. You can now command the altimeter to fire the apogee
497 or main charges from a safe distance using your computer and
498 TeleDongle and the Fire Igniter tab to complete ejection testing.
502 <title>Radio Link </title>
504 The chip our boards are based on incorporates an RF transceiver, but
505 it's not a full duplex system... each end can only be transmitting or
506 receiving at any given moment. So we had to decide how to manage the
510 By design, the altimeter firmware listens for the radio link when
511 it's in "idle mode", which
512 allows us to use the radio link to configure the rocket, do things like
513 ejection tests, and extract data after a flight without having to
514 crack open the air-frame. However, when the board is in "flight
515 mode", the altimeter only
516 transmits and doesn't listen at all. That's because we want to put
517 ultimate priority on event detection and getting telemetry out of
519 the radio in case the rocket crashes and we aren't able to extract
523 We don't use a 'normal packet radio' mode like APRS because they're
524 just too inefficient. The GFSK modulation we use is FSK with the
525 base-band pulses passed through a
526 Gaussian filter before they go into the modulator to limit the
527 transmitted bandwidth. When combined with the hardware forward error
528 correction support in the cc1111 chip, this allows us to have a very
529 robust 38.4 kilobit data link with only 10 milliwatts of transmit
530 power, a whip antenna in the rocket, and a hand-held Yagi on the
531 ground. We've had flights to above 21k feet AGL with great reception,
532 and calculations suggest we should be good to well over 40k feet AGL
533 with a 5-element yagi on the ground. We hope to fly boards to higher
534 altitudes over time, and would of course appreciate customer feedback
535 on performance in higher altitude flights!
539 <title>Configurable Parameters</title>
541 Configuring an Altus Metrum altimeter for flight is very
542 simple. Even on our baro-only TeleMini board, the use of a Kalman
543 filter means there is no need to set a "mach delay". The few
544 configurable parameters can all be set using AltosUI over USB or
545 or radio link via TeleDongle.
548 <title>Radio Frequency</title>
550 Altus Metrum boards support radio frequencies in the 70cm
551 band. By default, the configuration interface provides a
552 list of 10 "standard" frequencies in 100kHz channels starting at
553 434.550MHz. However, the firmware supports use of
554 any 50kHz multiple within the 70cm band. At any given
555 launch, we highly recommend coordinating when and by whom each
556 frequency will be used to avoid interference. And of course, both
557 altimeter and TeleDongle must be configured to the same
558 frequency to successfully communicate with each other.
562 <title>Apogee Delay</title>
564 Apogee delay is the number of seconds after the altimeter detects flight
565 apogee that the drogue charge should be fired. In most cases, this
566 should be left at the default of 0. However, if you are flying
567 redundant electronics such as for an L3 certification, you may wish
568 to set one of your altimeters to a positive delay so that both
569 primary and backup pyrotechnic charges do not fire simultaneously.
572 The Altus Metrum apogee detection algorithm fires exactly at
573 apogee. If you are also flying an altimeter like the
574 PerfectFlite MAWD, which only supports selecting 0 or 1
575 seconds of apogee delay, you may wish to set the MAWD to 0
576 seconds delay and set the TeleMetrum to fire your backup 2
577 or 3 seconds later to avoid any chance of both charges
578 firing simultaneously. We've flown several air-frames this
579 way quite happily, including Keith's successful L3 cert.
583 <title>Main Deployment Altitude</title>
585 By default, the altimeter will fire the main deployment charge at an
586 elevation of 250 meters (about 820 feet) above ground. We think this
587 is a good elevation for most air-frames, but feel free to change this
588 to suit. In particular, if you are flying two altimeters, you may
590 deployment elevation for the backup altimeter to be something lower
591 than the primary so that both pyrotechnic charges don't fire
596 <title>Maximum Flight Log</title>
598 TeleMetrum version 1.1 and 1.2 have 2MB of on-board flash storage,
599 enough to hold over 40 minutes of data at full data rate
600 (100 samples/second). TeleMetrum 1.0 has 1MB of on-board
601 storage. As data are stored at a reduced rate during descent
602 (10 samples/second), there's plenty of space to store many
603 flights worth of data.
606 The on-board flash is partitioned into separate flight logs,
607 each of a fixed maximum size. Increase the maximum size of
608 each log and you reduce the number of flights that can be
609 stored. Decrease the size and TeleMetrum can store more
613 All of the configuration data is also stored in the flash
614 memory, which consumes 64kB on TeleMetrum v1.1/v1.2 and 256B on
615 TeleMetrum v1.0. This configuration space is not available
616 for storing flight log data.
619 To compute the amount of space needed for a single flight,
620 you can multiply the expected ascent time (in seconds) by
621 800, multiply the expected descent time (in seconds) by 80
622 and add the two together. That will slightly under-estimate
623 the storage (in bytes) needed for the flight. For instance,
624 a flight spending 20 seconds in ascent and 150 seconds in
625 descent will take about (20 * 800) + (150 * 80) = 28000
626 bytes of storage. You could store dozens of these flights in
630 The default size, 192kB, allows for 10 flights of storage on
631 TeleMetrum v1.1/v1.2 and 5 flights on TeleMetrum v1.0. This
632 ensures that you won't need to erase the memory before
633 flying each time while still allowing more than sufficient
634 storage for each flight.
637 As TeleMini does not contain an accelerometer, it stores
638 data at 10 samples per second during ascent and one sample
639 per second during descent. Each sample is a two byte reading
640 from the barometer. These are stored in 5kB of
641 on-chip flash memory which can hold 256 seconds at the
642 ascent rate or 2560 seconds at the descent rate. Because of
643 the limited storage, TeleMini cannot hold data for more than
644 one flight, and so must be erased after each flight or it
645 will not capture data for subsequent flights.
649 <title>Ignite Mode</title>
651 Instead of firing one charge at apogee and another charge at
652 a fixed height above the ground, you can configure the
653 altimeter to fire both at apogee or both during
654 descent. This was added to support an airframe that has two
655 TeleMetrum computers, one in the fin can and one in the
659 Providing the ability to use both igniters for apogee or
660 main allows some level of redundancy without needing two
661 flight computers. In Redundant Apogee or Redundant Main
662 mode, the two charges will be fired two seconds apart.
666 <title>Pad Orientation</title>
668 TeleMetrum measures acceleration along the axis of the
669 board. Which way the board is oriented affects the sign of
670 the acceleration value. Instead of trying to guess which way
671 the board is mounted in the air frame, TeleMetrum must be
672 explicitly configured for either Antenna Up or Antenna
673 Down. The default, Antenna Up, expects the end of the
674 TeleMetrum board connected to the 70cm antenna to be nearest
675 the nose of the rocket, with the end containing the screw
676 terminals nearest the tail.
684 <title>AltosUI</title>
686 The AltosUI program provides a graphical user interface for
687 interacting with the Altus Metrum product family, including
688 TeleMetrum, TeleMini and TeleDongle. AltosUI can monitor telemetry data,
689 configure TeleMetrum, TeleMini and TeleDongle devices and many other
690 tasks. The primary interface window provides a selection of
691 buttons, one for each major activity in the system. This manual
692 is split into chapters, each of which documents one of the tasks
693 provided from the top-level toolbar.
696 <title>Monitor Flight</title>
697 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
699 Selecting this item brings up a dialog box listing all of the
700 connected TeleDongle devices. When you choose one of these,
701 AltosUI will create a window to display telemetry data as
702 received by the selected TeleDongle device.
705 All telemetry data received are automatically recorded in
706 suitable log files. The name of the files includes the current
707 date and rocket serial and flight numbers.
710 The radio frequency being monitored by the TeleDongle device is
711 displayed at the top of the window. You can configure the
712 frequency by clicking on the frequency box and selecting the desired
713 frequency. AltosUI remembers the last frequency selected for each
714 TeleDongle and selects that automatically the next time you use
718 Below the TeleDongle frequency selector, the window contains a few
719 significant pieces of information about the altimeter providing
720 the telemetry data stream:
724 <para>The configured call-sign</para>
727 <para>The device serial number</para>
730 <para>The flight number. Each altimeter remembers how many
736 The rocket flight state. Each flight passes through several
737 states including Pad, Boost, Fast, Coast, Drogue, Main and
743 The Received Signal Strength Indicator value. This lets
744 you know how strong a signal TeleDongle is receiving. The
745 radio inside TeleDongle operates down to about -99dBm;
746 weaker signals may not be receivable. The packet link uses
747 error detection and correction techniques which prevent
748 incorrect data from being reported.
753 Finally, the largest portion of the window contains a set of
754 tabs, each of which contain some information about the rocket.
755 They're arranged in 'flight order' so that as the flight
756 progresses, the selected tab automatically switches to display
757 data relevant to the current state of the flight. You can select
758 other tabs at any time. The final 'table' tab displays all of
759 the raw telemetry values in one place in a spreadsheet-like format.
762 <title>Launch Pad</title>
764 The 'Launch Pad' tab shows information used to decide when the
765 rocket is ready for flight. The first elements include red/green
766 indicators, if any of these is red, you'll want to evaluate
767 whether the rocket is ready to launch:
771 Battery Voltage. This indicates whether the Li-Po battery
772 powering the TeleMetrum has sufficient charge to last for
773 the duration of the flight. A value of more than
774 3.7V is required for a 'GO' status.
779 Apogee Igniter Voltage. This indicates whether the apogee
780 igniter has continuity. If the igniter has a low
781 resistance, then the voltage measured here will be close
782 to the Li-Po battery voltage. A value greater than 3.2V is
783 required for a 'GO' status.
788 Main Igniter Voltage. This indicates whether the main
789 igniter has continuity. If the igniter has a low
790 resistance, then the voltage measured here will be close
791 to the Li-Po battery voltage. A value greater than 3.2V is
792 required for a 'GO' status.
797 On-board Data Logging. This indicates whether there is
798 space remaining on-board to store flight data for the
799 upcoming flight. If you've downloaded data, but failed
800 to erase flights, there may not be any space
801 left. TeleMetrum can store multiple flights, depending
802 on the configured maximum flight log size. TeleMini
803 stores only a single flight, so it will need to be
804 downloaded and erased after each flight to capture
805 data. This only affects on-board flight logging; the
806 altimeter will still transmit telemetry and fire
807 ejection charges at the proper times.
812 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
813 currently able to compute position information. GPS requires
814 at least 4 satellites to compute an accurate position.
819 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
820 10 consecutive positions without losing lock. This ensures
821 that the GPS receiver has reliable reception from the
827 The Launchpad tab also shows the computed launch pad position
828 and altitude, averaging many reported positions to improve the
834 <title>Ascent</title>
836 This tab is shown during Boost, Fast and Coast
837 phases. The information displayed here helps monitor the
838 rocket as it heads towards apogee.
841 The height, speed and acceleration are shown along with the
842 maximum values for each of them. This allows you to quickly
843 answer the most commonly asked questions you'll hear during
847 The current latitude and longitude reported by the TeleMetrum GPS are
848 also shown. Note that under high acceleration, these values
849 may not get updated as the GPS receiver loses position
850 fix. Once the rocket starts coasting, the receiver should
851 start reporting position again.
854 Finally, the current igniter voltages are reported as in the
855 Launch Pad tab. This can help diagnose deployment failures
856 caused by wiring which comes loose under high acceleration.
860 <title>Descent</title>
862 Once the rocket has reached apogee and (we hope) activated the
863 apogee charge, attention switches to tracking the rocket on
864 the way back to the ground, and for dual-deploy flights,
865 waiting for the main charge to fire.
868 To monitor whether the apogee charge operated correctly, the
869 current descent rate is reported along with the current
870 height. Good descent rates vary based on the choice of recovery
871 components, but generally range from 15-30m/s on drogue and should
872 be below 10m/s when under the main parachute in a dual-deploy flight.
875 For TeleMetrum altimeters, you can locate the rocket in the sky
876 using the elevation and
877 bearing information to figure out where to look. Elevation is
878 in degrees above the horizon. Bearing is reported in degrees
879 relative to true north. Range can help figure out how big the
880 rocket will appear. Note that all of these values are relative
881 to the pad location. If the elevation is near 90°, the rocket
882 is over the pad, not over you.
885 Finally, the igniter voltages are reported in this tab as
886 well, both to monitor the main charge as well as to see what
887 the status of the apogee charge is. Note that some commercial
888 e-matches are designed to retain continuity even after being
889 fired, and will continue to show as green or return from red to
894 <title>Landed</title>
896 Once the rocket is on the ground, attention switches to
897 recovery. While the radio signal is often lost once the
898 rocket is on the ground, the last reported GPS position is
899 generally within a short distance of the actual landing location.
902 The last reported GPS position is reported both by
903 latitude and longitude as well as a bearing and distance from
904 the launch pad. The distance should give you a good idea of
905 whether to walk or hitch a ride. Take the reported
906 latitude and longitude and enter them into your hand-held GPS
907 unit and have that compute a track to the landing location.
910 Both TeleMini and TeleMetrum will continue to transmit RDF
911 tones after landing, allowing you to locate the rocket by
912 following the radio signal if necessary. You may need to get
913 away from the clutter of the flight line, or even get up on
914 a hill (or your neighbor's RV roof) to receive the RDF signal.
917 The maximum height, speed and acceleration reported
918 during the flight are displayed for your admiring observers.
919 The accuracy of these immediate values depends on the quality
920 of your radio link and how many packets were received.
921 Recovering the on-board data after flight will likely yield
922 more precise results.
925 To get more detailed information about the flight, you can
926 click on the 'Graph Flight' button which will bring up a
927 graph window for the current flight.
931 <title>Site Map</title>
933 When the TeleMetrum has a GPS fix, the Site Map tab will map
934 the rocket's position to make it easier for you to locate the
935 rocket, both while it is in the air, and when it has landed. The
936 rocket's state is indicated by color: white for pad, red for
937 boost, pink for fast, yellow for coast, light blue for drogue,
938 dark blue for main, and black for landed.
941 The map's scale is approximately 3m (10ft) per pixel. The map
942 can be dragged using the left mouse button. The map will attempt
943 to keep the rocket roughly centered while data is being received.
946 Images are fetched automatically via the Google Maps Static API,
947 and cached on disk for reuse. If map images cannot be downloaded,
948 the rocket's path will be traced on a dark gray background
952 You can pre-load images for your favorite launch sites
953 before you leave home; check out the 'Preload Maps' section below.
958 <title>Save Flight Data</title>
960 The altimeter records flight data to its internal flash memory.
961 TeleMetrum data is recorded at a much higher rate than the telemetry
962 system can handle, and is not subject to radio drop-outs. As
963 such, it provides a more complete and precise record of the
964 flight. The 'Save Flight Data' button allows you to read the
965 flash memory and write it to disk. As TeleMini has only a barometer, it
966 records data at the same rate as the telemetry signal, but there will be
967 no data lost due to telemetry drop-outs.
970 Clicking on the 'Save Flight Data' button brings up a list of
971 connected TeleMetrum and TeleDongle devices. If you select a
972 TeleMetrum device, the flight data will be downloaded from that
973 device directly. If you select a TeleDongle device, flight data
974 will be downloaded from an altimeter over radio link via the
975 specified TeleDongle. See the chapter on Controlling An Altimeter
976 Over The Radio Link for more information.
979 After the device has been selected, a dialog showing the
980 flight data saved in the device will be shown allowing you to
981 select which flights to download and which to delete. With
982 version 0.9 or newer firmware, you must erase flights in order
983 for the space they consume to be reused by another
984 flight. This prevents accidentally losing flight data
985 if you neglect to download data before flying again. Note that
986 if there is no more space available in the device, then no
987 data will be recorded during the next flight.
990 The file name for each flight log is computed automatically
991 from the recorded flight date, altimeter serial number and
992 flight number information.
996 <title>Replay Flight</title>
998 Select this button and you are prompted to select a flight
999 record file, either a .telem file recording telemetry data or a
1000 .eeprom file containing flight data saved from the altimeter
1004 Once a flight record is selected, the flight monitor interface
1005 is displayed and the flight is re-enacted in real time. Check
1006 the Monitor Flight chapter above to learn how this window operates.
1010 <title>Graph Data</title>
1012 Select this button and you are prompted to select a flight
1013 record file, either a .telem file recording telemetry data or a
1014 .eeprom file containing flight data saved from
1018 Once a flight record is selected, a window with two tabs is
1019 opened. The first tab contains a graph with acceleration
1020 (blue), velocity (green) and altitude (red) of the flight,
1021 measured in metric units. The
1022 apogee(yellow) and main(magenta) igniter voltages are also
1023 displayed; high voltages indicate continuity, low voltages
1024 indicate open circuits. The second tab contains some basic
1028 The graph can be zoomed into a particular area by clicking and
1029 dragging down and to the right. Once zoomed, the graph can be
1030 reset by clicking and dragging up and to the left. Holding down
1031 control and clicking and dragging allows the graph to be panned.
1032 The right mouse button causes a pop-up menu to be displayed, giving
1033 you the option save or print the plot.
1036 Note that telemetry files will generally produce poor graphs
1037 due to the lower sampling rate and missed telemetry packets.
1038 Use saved flight data in .eeprom files for graphing where possible.
1042 <title>Export Data</title>
1044 This tool takes the raw data files and makes them available for
1045 external analysis. When you select this button, you are prompted to
1047 data file (either .eeprom or .telem will do, remember that
1048 .eeprom files contain higher resolution and more continuous
1049 data). Next, a second dialog appears which is used to select
1050 where to write the resulting file. It has a selector to choose
1051 between CSV and KML file formats.
1054 <title>Comma Separated Value Format</title>
1056 This is a text file containing the data in a form suitable for
1057 import into a spreadsheet or other external data analysis
1058 tool. The first few lines of the file contain the version and
1059 configuration information from the altimeter, then
1060 there is a single header line which labels all of the
1061 fields. All of these lines start with a '#' character which
1062 many tools can be configured to skip over.
1065 The remaining lines of the file contain the data, with each
1066 field separated by a comma and at least one space. All of
1067 the sensor values are converted to standard units, with the
1068 barometric data reported in both pressure, altitude and
1069 height above pad units.
1073 <title>Keyhole Markup Language (for Google Earth)</title>
1075 This is the format used by Google Earth to provide an overlay
1076 within that application. With this, you can use Google Earth to
1077 see the whole flight path in 3D.
1082 <title>Configure Altimeter</title>
1084 Select this button and then select either a TeleMetrum or
1085 TeleDongle Device from the list provided. Selecting a TeleDongle
1086 device will use the radio link to configure a remote altimeter.
1089 The first few lines of the dialog provide information about the
1090 connected device, including the product name,
1091 software version and hardware serial number. Below that are the
1092 individual configuration entries.
1095 At the bottom of the dialog, there are four buttons:
1100 Save. This writes any changes to the
1101 configuration parameter block in flash memory. If you don't
1102 press this button, any changes you make will be lost.
1107 Reset. This resets the dialog to the most recently saved values,
1108 erasing any changes you have made.
1113 Reboot. This reboots the device. Use this to
1114 switch from idle to pad mode by rebooting once the rocket is
1115 oriented for flight, or to confirm changes you think you saved
1121 Close. This closes the dialog. Any unsaved changes will be
1127 The rest of the dialog contains the parameters to be configured.
1130 <title>Main Deploy Altitude</title>
1132 This sets the altitude (above the recorded pad altitude) at
1133 which the 'main' igniter will fire. The drop-down menu shows
1134 some common values, but you can edit the text directly and
1135 choose whatever you like. If the apogee charge fires below
1136 this altitude, then the main charge will fire two seconds
1137 after the apogee charge fires.
1141 <title>Apogee Delay</title>
1143 When flying redundant electronics, it's often important to
1144 ensure that multiple apogee charges don't fire at precisely
1145 the same time, as that can over pressurize the apogee deployment
1146 bay and cause a structural failure of the air-frame. The Apogee
1147 Delay parameter tells the flight computer to fire the apogee
1148 charge a certain number of seconds after apogee has been
1153 <title>Radio Frequency</title>
1155 This configures which of the configured frequencies to use for both
1156 telemetry and packet command mode. Note that if you set this
1157 value via packet command mode, you will have to reconfigure
1158 the TeleDongle frequency before you will be able to use packet
1163 <title>Radio Calibration</title>
1165 The radios in every Altus Metrum device are calibrated at the
1166 factory to ensure that they transmit and receive on the
1167 specified frequency. If you need to you can adjust the calibration
1168 by changing this value. Do not do this without understanding what
1169 the value means, read the appendix on calibration and/or the source
1170 code for more information. To change a TeleDongle's calibration,
1171 you must reprogram the unit completely.
1175 <title>Callsign</title>
1177 This sets the call sign included in each telemetry packet. Set this
1178 as needed to conform to your local radio regulations.
1182 <title>Maximum Flight Log Size</title>
1184 This sets the space (in kilobytes) allocated for each flight
1185 log. The available space will be divided into chunks of this
1186 size. A smaller value will allow more flights to be stored,
1187 a larger value will record data from longer flights.
1191 <title>Ignite Mode</title>
1193 TeleMetrum and TeleMini provide two igniter channels as they
1194 were originally designed as dual-deploy flight
1195 computers. This configuration parameter allows the two
1196 channels to be used in different configurations.
1201 Dual Deploy. This is the usual mode of operation; the
1202 'apogee' channel is fired at apogee and the 'main'
1203 channel at the height above ground specified by the
1204 'Main Deploy Altitude' during descent.
1209 Redundant Apogee. This fires both channels at
1210 apogee, the 'apogee' channel first followed after a two second
1211 delay by the 'main' channel.
1216 Redundant Main. This fires both channels at the
1217 height above ground specified by the Main Deploy
1218 Altitude setting during descent. The 'apogee'
1219 channel is fired first, followed after a two second
1220 delay by the 'main' channel.
1226 <title>Pad Orientation</title>
1228 Because it includes an accelerometer, TeleMetrum is
1229 sensitive to the orientation of the board. By default, it
1230 expects the antenna end to point forward. This parameter
1231 allows that default to be changed, permitting the board to
1232 be mounted with the antenna pointing aft instead.
1237 Antenna Up. In this mode, the antenna end of the
1238 TeleMetrum board must point forward, in line with the
1239 expected flight path.
1244 Antenna Down. In this mode, the antenna end of the
1245 TeleMetrum board must point aft, in line with the
1246 expected flight path.
1253 <title>Configure AltosUI</title>
1255 This button presents a dialog so that you can configure the AltosUI global settings.
1258 <title>Voice Settings</title>
1260 AltosUI provides voice announcements during flight so that you
1261 can keep your eyes on the sky and still get information about
1262 the current flight status. However, sometimes you don't want
1267 <para>Enable—turns all voice announcements on and off</para>
1271 Test Voice—Plays a short message allowing you to verify
1272 that the audio system is working and the volume settings
1279 <title>Log Directory</title>
1281 AltosUI logs all telemetry data and saves all TeleMetrum flash
1282 data to this directory. This directory is also used as the
1283 staring point when selecting data files for display or export.
1286 Click on the directory name to bring up a directory choosing
1287 dialog, select a new directory and click 'Select Directory' to
1288 change where AltosUI reads and writes data files.
1292 <title>Callsign</title>
1294 This value is transmitted in each command packet sent from
1295 TeleDongle and received from an altimeter. It is not used in
1296 telemetry mode, as the callsign configured in the altimeter board
1297 is included in all telemetry packets. Configure this
1298 with the AltosUI operators call sign as needed to comply with
1299 your local radio regulations.
1303 <title>Imperial Units</title>
1305 This switches between metric units (meters) and imperial
1306 units (feet and miles). This affects the display of values
1307 use during flight monitoring, data graphing and all of the
1308 voice announcements. It does not change the units used when
1309 exporting to CSV files, those are always produced in metric units.
1313 <title>Font Size</title>
1315 Selects the set of fonts used in the flight monitor
1316 window. Choose between the small, medium and large sets.
1320 <title>Serial Debug</title>
1322 This causes all communication with a connected device to be
1323 dumped to the console from which AltosUI was started. If
1324 you've started it from an icon or menu entry, the output
1325 will simply be discarded. This mode can be useful to debug
1326 various serial communication issues.
1330 <title>Manage Frequencies</title>
1332 This brings up a dialog where you can configure the set of
1333 frequencies shown in the various frequency menus. You can
1334 add as many as you like, or even reconfigure the default
1335 set. Changing this list does not affect the frequency
1336 settings of any devices, it only changes the set of
1337 frequencies shown in the menus.
1342 <title>Configure Groundstation</title>
1344 Select this button and then select a TeleDongle Device from the list provided.
1347 The first few lines of the dialog provide information about the
1348 connected device, including the product name,
1349 software version and hardware serial number. Below that are the
1350 individual configuration entries.
1353 Note that the TeleDongle itself doesn't save any configuration
1354 data, the settings here are recorded on the local machine in
1355 the Java preferences database. Moving the TeleDongle to
1356 another machine, or using a different user account on the same
1357 machine will cause settings made here to have no effect.
1360 At the bottom of the dialog, there are three buttons:
1365 Save. This writes any changes to the
1366 local Java preferences file. If you don't
1367 press this button, any changes you make will be lost.
1372 Reset. This resets the dialog to the most recently saved values,
1373 erasing any changes you have made.
1378 Close. This closes the dialog. Any unsaved changes will be
1384 The rest of the dialog contains the parameters to be configured.
1387 <title>Frequency</title>
1389 This configures the frequency to use for both telemetry and
1390 packet command mode. Set this before starting any operation
1391 involving packet command mode so that it will use the right
1392 frequency. Telemetry monitoring mode also provides a menu to
1393 change the frequency, and that menu also sets the same Java
1394 preference value used here.
1398 <title>Radio Calibration</title>
1400 The radios in every Altus Metrum device are calibrated at the
1401 factory to ensure that they transmit and receive on the
1402 specified frequency. To change a TeleDongle's calibration,
1403 you must reprogram the unit completely, so this entry simply
1404 shows the current value and doesn't allow any changes.
1409 <title>Flash Image</title>
1411 This reprograms any Altus Metrum device by using a TeleMetrum
1412 or TeleDongle as a programming dongle. Please read the
1413 directions for flashing devices in the Updating Device
1414 Firmware chapter below.
1417 Once you have the programmer and target devices connected,
1418 push the 'Flash Image' button. That will present a dialog box
1419 listing all of the connected devices. Carefully select the
1420 programmer device, not the device to be programmed.
1423 Next, select the image to flash to the device. These are named
1424 with the product name and firmware version. The file selector
1425 will start in the directory containing the firmware included
1426 with the AltosUI package. Navigate to the directory containing
1427 the desired firmware if it isn't there.
1430 Next, a small dialog containing the device serial number and
1431 RF calibration values should appear. If these values are
1432 incorrect (possibly due to a corrupted image in the device),
1433 enter the correct values here.
1436 Finally, a dialog containing a progress bar will follow the
1437 programming process.
1440 When programming is complete, the target device will
1441 reboot. Note that if the target device is connected via USB, you
1442 will have to unplug it and then plug it back in for the USB
1443 connection to reset so that you can communicate with the device
1448 <title>Fire Igniter</title>
1450 This activates the igniter circuits in TeleMetrum to help test
1451 recovery systems deployment. Because this command can operate
1452 over the Packet Command Link, you can prepare the rocket as
1453 for flight and then test the recovery system without needing
1454 to snake wires inside the air-frame.
1457 Selecting the 'Fire Igniter' button brings up the usual device
1458 selection dialog. Pick the desired TeleDongle or TeleMetrum
1459 device. This brings up another window which shows the current
1460 continuity test status for both apogee and main charges.
1463 Next, select the desired igniter to fire. This will enable the
1467 Select the 'Arm' button. This enables the 'Fire' button. The
1468 word 'Arm' is replaced by a countdown timer indicating that
1469 you have 10 seconds to press the 'Fire' button or the system
1470 will deactivate, at which point you start over again at
1471 selecting the desired igniter.
1475 <title>Scan Channels</title>
1477 This listens for telemetry packets on all of the configured
1478 frequencies, displaying information about each device it
1479 receives a packet from. You can select which of the three
1480 telemetry formats should be tried; by default, it only listens
1481 for the standard telemetry packets used in v1.0 and later
1486 <title>Load Maps</title>
1488 Before heading out to a new launch site, you can use this to
1489 load satellite images in case you don't have internet
1490 connectivity at the site. This loads a fairly large area
1491 around the launch site, which should cover any flight you're likely to make.
1494 There's a drop-down menu of launch sites we know about; if
1495 your favorites aren't there, please let us know the lat/lon
1496 and name of the site. The contents of this list are actually
1497 downloaded at run-time, so as new sites are sent in, they'll
1498 get automatically added to this list.
1501 If the launch site isn't in the list, you can manually enter the lat/lon values
1504 Clicking the 'Load Map' button will fetch images from Google
1505 Maps; note that Google limits how many images you can fetch at
1506 once, so if you load more than one launch site, you may get
1507 some gray areas in the map which indicate that Google is tired
1508 of sending data to you. Try again later.
1512 <title>Monitor Idle</title>
1514 This brings up a dialog similar to the Monitor Flight UI,
1515 except it works with the altimeter in "idle" mode by sending
1516 query commands to discover the current state rather than
1517 listening for telemetry packets.
1522 <title>Using Altus Metrum Products</title>
1524 <title>Being Legal</title>
1526 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
1527 other authorization to legally operate the radio transmitters that are part
1532 <title>In the Rocket</title>
1534 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
1535 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
1536 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
1537 850mAh battery weighs less than a 9V alkaline battery, and will
1538 run a TeleMetrum for hours.
1539 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
1540 a few hours, or a TeleMini for much (much) longer.
1543 By default, we ship the altimeters with a simple wire antenna. If your
1544 electronics bay or the air-frame it resides within is made of carbon fiber,
1545 which is opaque to RF signals, you may choose to have an SMA connector
1546 installed so that you can run a coaxial cable to an antenna mounted
1547 elsewhere in the rocket.
1551 <title>On the Ground</title>
1553 To receive the data stream from the rocket, you need an antenna and short
1554 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. The
1555 TeleDongle in turn plugs directly into the USB port on a notebook
1556 computer. Because TeleDongle looks like a simple serial port, your computer
1557 does not require special device drivers... just plug it in.
1560 The GUI tool, AltosUI, is written in Java and runs across
1561 Linux, Mac OS and Windows. There's also a suite of C tools
1562 for Linux which can perform most of the same tasks.
1565 After the flight, you can use the radio link to extract the more detailed data
1566 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
1567 TeleMetrum board directly. Pulling out the data without having to open up
1568 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
1569 battery, so you'll want one of those anyway... the same cable used by lots
1570 of digital cameras and other modern electronic stuff will work fine.
1573 If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
1574 receiver, so that you can put in a way-point for the last reported rocket
1575 position before touch-down. This makes looking for your rocket a lot like
1576 Geo-Caching... just go to the way-point and look around starting from there.
1579 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
1580 can use that with your antenna to direction-find the rocket on the ground
1581 the same way you can use a Walston or Beeline tracker. This can be handy
1582 if the rocket is hiding in sage brush or a tree, or if the last GPS position
1583 doesn't get you close enough because the rocket dropped into a canyon, or
1584 the wind is blowing it across a dry lake bed, or something like that... Keith
1585 and Bdale both currently own and use the Yaesu VX-7R at launches.
1588 So, to recap, on the ground the hardware you'll need includes:
1589 <orderedlist inheritnum='inherit' numeration='arabic'>
1591 an antenna and feed-line
1600 optionally, a hand-held GPS receiver
1603 optionally, an HT or receiver covering 435 MHz
1608 The best hand-held commercial directional antennas we've found for radio
1609 direction finding rockets are from
1610 <ulink url="http://www.arrowantennas.com/" >
1613 The 440-3 and 440-5 are both good choices for finding a
1614 TeleMetrum- or TeleMini- equipped rocket when used with a suitable 70cm HT.
1618 <title>Data Analysis</title>
1620 Our software makes it easy to log the data from each flight, both the
1621 telemetry received during the flight itself, and the more
1622 complete data log recorded in the flash memory on the altimeter
1623 board. Once this data is on your computer, our post-flight tools make it
1624 easy to quickly get to the numbers everyone wants, like apogee altitude,
1625 max acceleration, and max velocity. You can also generate and view a
1626 standard set of plots showing the altitude, acceleration, and
1627 velocity of the rocket during flight. And you can even export a TeleMetrum data file
1628 usable with Google Maps and Google Earth for visualizing the flight path
1629 in two or three dimensions!
1632 Our ultimate goal is to emit a set of files for each flight that can be
1633 published as a web page per flight, or just viewed on your local disk with
1638 <title>Future Plans</title>
1640 In the future, we intend to offer "companion boards" for the rocket that will
1641 plug in to TeleMetrum to collect additional data, provide more pyro channels,
1645 We are also working on the design of a hand-held ground terminal that will
1646 allow monitoring the rocket's status, collecting data during flight, and
1647 logging data after flight without the need for a notebook computer on the
1648 flight line. Particularly since it is so difficult to read most notebook
1649 screens in direct sunlight, we think this will be a great thing to have.
1652 Because all of our work is open, both the hardware designs and the software,
1653 if you have some great idea for an addition to the current Altus Metrum family,
1654 feel free to dive in and help! Or let us know what you'd like to see that
1655 we aren't already working on, and maybe we'll get excited about it too...
1660 <title>Altimeter Installation Recommendations</title>
1662 Building high-power rockets that fly safely is hard enough. Mix
1663 in some sophisticated electronics and a bunch of radio energy
1664 and oftentimes you find few perfect solutions. This chapter
1665 contains some suggestions about how to install Altus Metrum
1666 products into the rocket air-frame, including how to safely and
1667 reliably mix a variety of electronics into the same air-frame.
1670 <title>Mounting the Altimeter</title>
1672 The first consideration is to ensure that the altimeter is
1673 securely fastened to the air-frame. For TeleMetrum, we use
1674 nylon standoffs and nylon screws; they're good to at least 50G
1675 and cannot cause any electrical issues on the board. For
1676 TeleMini, we usually cut small pieces of 1/16" balsa to fit
1677 under the screw holes, and then take 2x56 nylon screws and
1678 screw them through the TeleMini mounting holes, through the
1679 balsa and into the underlying material.
1681 <orderedlist inheritnum='inherit' numeration='arabic'>
1683 Make sure TeleMetrum is aligned precisely along the axis of
1684 acceleration so that the accelerometer can accurately
1685 capture data during the flight.
1688 Watch for any metal touching components on the
1689 board. Shorting out connections on the bottom of the board
1690 can cause the altimeter to fail during flight.
1695 <title>Dealing with the Antenna</title>
1697 The antenna supplied is just a piece of solid, insulated,
1698 wire. If it gets damaged or broken, it can be easily
1699 replaced. It should be kept straight and not cut; bending or
1700 cutting it will change the resonant frequency and/or
1701 impedance, making it a less efficient radiator and thus
1702 reducing the range of the telemetry signal.
1705 Keeping metal away from the antenna will provide better range
1706 and a more even radiation pattern. In most rockets, it's not
1707 entirely possible to isolate the antenna from metal
1708 components; there are often bolts, all-thread and wires from other
1709 electronics to contend with. Just be aware that the more stuff
1710 like this around the antenna, the lower the range.
1713 Make sure the antenna is not inside a tube made or covered
1714 with conducting material. Carbon fiber is the most common
1715 culprit here -- CF is a good conductor and will effectively
1716 shield the antenna, dramatically reducing signal strength and
1717 range. Metallic flake paint is another effective shielding
1718 material which is to be avoided around any antennas.
1721 If the ebay is large enough, it can be convenient to simply
1722 mount the altimeter at one end and stretch the antenna out
1723 inside. Taping the antenna to the sled can keep it straight
1724 under acceleration. If there are metal rods, keep the
1725 antenna as far away as possible.
1728 For a shorter ebay, it's quite practical to have the antenna
1729 run through a bulkhead and into an adjacent bay. Drill a small
1730 hole in the bulkhead, pass the antenna wire through it and
1731 then seal it up with glue or clay. We've also used acrylic
1732 tubing to create a cavity for the antenna wire. This works a
1733 bit better in that the antenna is known to stay straight and
1734 not get folded by recovery components in the bay. Angle the
1735 tubing towards the side wall of the rocket and it ends up
1736 consuming very little space.
1739 If you need to place the antenna at a distance from the
1740 altimeter, you can replace the antenna with an edge-mounted
1741 SMA connector, and then run 50Ω coax from the board to the
1742 antenna. Building a remote antenna is beyond the scope of this
1747 <title>Preserving GPS Reception</title>
1749 The GPS antenna and receiver in TeleMetrum are highly
1750 sensitive and normally have no trouble tracking enough
1751 satellites to provide accurate position information for
1752 recovering the rocket. However, there are many ways to
1753 attenuate the GPS signal.
1754 <orderedlist inheritnum='inherit' numeration='arabic'>
1756 Conductive tubing or coatings. Carbon fiber and metal
1757 tubing, or metallic paint will all dramatically attenuate the
1758 GPS signal. We've never heard of anyone successfully
1759 receiving GPS from inside these materials.
1762 Metal components near the GPS patch antenna. These will
1763 de-tune the patch antenna, changing the resonant frequency
1764 away from the L1 carrier and reduce the effectiveness of the
1765 antenna. You can place as much stuff as you like beneath the
1766 antenna as that's covered with a ground plane. But, keep
1767 wires and metal out from above the patch antenna.
1773 <title>Radio Frequency Interference</title>
1775 Any altimeter will generate RFI; the digital circuits use
1776 high-frequency clocks that spray radio interference across a
1777 wide band. Altus Metrum altimeters generate intentional radio
1778 signals as well, increasing the amount of RF energy around the board.
1781 Rocketry altimeters also use precise sensors measuring air
1782 pressure and acceleration. Tiny changes in voltage can cause
1783 these sensor readings to vary by a huge amount. When the
1784 sensors start mis-reporting data, the altimeter can either
1785 fire the igniters at the wrong time, or not fire them at all.
1788 Voltages are induced when radio frequency energy is
1789 transmitted from one circuit to another. Here are things that
1790 influence the induced voltage and current:
1794 Keep wires from different circuits apart. Moving circuits
1795 further apart will reduce RFI.
1798 Avoid parallel wires from different circuits. The longer two
1799 wires run parallel to one another, the larger the amount of
1800 transferred energy. Cross wires at right angles to reduce
1804 Twist wires from the same circuits. Two wires the same
1805 distance from the transmitter will get the same amount of
1806 induced energy which will then cancel out. Any time you have
1807 a wire pair running together, twist the pair together to
1808 even out distances and reduce RFI. For altimeters, this
1809 includes battery leads, switch hookups and igniter
1813 Avoid resonant lengths. Know what frequencies are present
1814 in the environment and avoid having wire lengths near a
1815 natural resonant length. Altusmetrum products transmit on the
1816 70cm amateur band, so you should avoid lengths that are a
1817 simple ratio of that length; essentially any multiple of 1/4
1818 of the wavelength (17.5cm).
1823 <title>The Barometric Sensor</title>
1825 Altusmetrum altimeters measure altitude with a barometric
1826 sensor, essentially measuring the amount of air above the
1827 rocket to figure out how high it is. A large number of
1828 measurements are taken as the altimeter initializes itself to
1829 figure out the pad altitude. Subsequent measurements are then
1830 used to compute the height above the pad.
1833 To accurately measure atmospheric pressure, the ebay
1834 containing the altimeter must be vented outside the
1835 air-frame. The vent must be placed in a region of linear
1836 airflow, have smooth edges, and away from areas of increasing or
1837 decreasing pressure.
1840 The barometric sensor in the altimeter is quite sensitive to
1841 chemical damage from the products of APCP or BP combustion, so
1842 make sure the ebay is carefully sealed from any compartment
1843 which contains ejection charges or motors.
1847 <title>Ground Testing</title>
1849 The most important aspect of any installation is careful
1850 ground testing. Bringing an air-frame up to the LCO table which
1851 hasn't been ground tested can lead to delays or ejection
1852 charges firing on the pad, or, even worse, a recovery system
1856 Do a 'full systems' test that includes wiring up all igniters
1857 without any BP and turning on all of the electronics in flight
1858 mode. This will catch any mistakes in wiring and any residual
1859 RFI issues that might accidentally fire igniters at the wrong
1860 time. Let the air-frame sit for several minutes, checking for
1861 adequate telemetry signal strength and GPS lock. If any igniters
1862 fire unexpectedly, find and resolve the issue before loading any
1866 Ground test the ejection charges. Prepare the rocket for
1867 flight, loading ejection charges and igniters. Completely
1868 assemble the air-frame and then use the 'Fire Igniters'
1869 interface through a TeleDongle to command each charge to
1870 fire. Make sure the charge is sufficient to robustly separate
1871 the air-frame and deploy the recovery system.
1876 <title>Updating Device Firmware</title>
1878 The big concept to understand is that you have to use a
1879 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
1880 and a TeleMetrum or other TeleDongle to program the TeleDongle
1881 Due to limited memory resources in the cc1111, we don't support
1882 programming directly over USB.
1885 You may wish to begin by ensuring you have current firmware images.
1886 These are distributed as part of the AltOS software bundle that
1887 also includes the AltosUI ground station program. Newer ground
1888 station versions typically work fine with older firmware versions,
1889 so you don't need to update your devices just to try out new
1890 software features. You can always download the most recent
1891 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
1894 We recommend updating the altimeter first, before updating TeleDongle.
1897 <title>Updating TeleMetrum Firmware</title>
1898 <orderedlist inheritnum='inherit' numeration='arabic'>
1900 Find the 'programming cable' that you got as part of the starter
1901 kit, that has a red 8-pin MicroMaTch connector on one end and a
1902 red 4-pin MicroMaTch connector on the other end.
1905 Take the 2 screws out of the TeleDongle case to get access
1906 to the circuit board.
1909 Plug the 8-pin end of the programming cable to the
1910 matching connector on the TeleDongle, and the 4-pin end to the
1911 matching connector on the TeleMetrum.
1912 Note that each MicroMaTch connector has an alignment pin that
1913 goes through a hole in the PC board when you have the cable
1917 Attach a battery to the TeleMetrum board.
1920 Plug the TeleDongle into your computer's USB port, and power
1924 Run AltosUI, and select 'Flash Image' from the File menu.
1927 Pick the TeleDongle device from the list, identifying it as the
1931 Select the image you want put on the TeleMetrum, which should have a
1932 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
1933 in the default directory, if not you may have to poke around
1934 your system to find it.
1937 Make sure the configuration parameters are reasonable
1938 looking. If the serial number and/or RF configuration
1939 values aren't right, you'll need to change them.
1942 Hit the 'OK' button and the software should proceed to flash
1943 the TeleMetrum with new firmware, showing a progress bar.
1946 Confirm that the TeleMetrum board seems to have updated OK, which you
1947 can do by plugging in to it over USB and using a terminal program
1948 to connect to the board and issue the 'v' command to check
1952 If something goes wrong, give it another try.
1957 <title>Updating TeleMini Firmware</title>
1958 <orderedlist inheritnum='inherit' numeration='arabic'>
1960 You'll need a special 'programming cable' to reprogram the
1961 TeleMini. It's available on the Altus Metrum web store, or
1962 you can make your own using an 8-pin MicroMaTch connector on
1963 one end and a set of four pins on the other.
1966 Take the 2 screws out of the TeleDongle case to get access
1967 to the circuit board.
1970 Plug the 8-pin end of the programming cable to the matching
1971 connector on the TeleDongle, and the 4-pins into the holes
1972 in the TeleMini circuit board. Note that the MicroMaTch
1973 connector has an alignment pin that goes through a hole in
1974 the PC board when you have the cable oriented correctly, and
1975 that pin 1 on the TeleMini board is marked with a square pad
1976 while the other pins have round pads.
1979 Attach a battery to the TeleMini board.
1982 Plug the TeleDongle into your computer's USB port, and power
1986 Run AltosUI, and select 'Flash Image' from the File menu.
1989 Pick the TeleDongle device from the list, identifying it as the
1993 Select the image you want put on the TeleMini, which should have a
1994 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
1995 in the default directory, if not you may have to poke around
1996 your system to find it.
1999 Make sure the configuration parameters are reasonable
2000 looking. If the serial number and/or RF configuration
2001 values aren't right, you'll need to change them.
2004 Hit the 'OK' button and the software should proceed to flash
2005 the TeleMini with new firmware, showing a progress bar.
2008 Confirm that the TeleMini board seems to have updated OK, which you
2009 can do by configuring it over the radio link through the TeleDongle, or
2010 letting it come up in "flight" mode and listening for telemetry.
2013 If something goes wrong, give it another try.
2018 <title>Updating TeleDongle Firmware</title>
2020 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
2021 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
2023 <orderedlist inheritnum='inherit' numeration='arabic'>
2025 Find the 'programming cable' that you got as part of the starter
2026 kit, that has a red 8-pin MicroMaTch connector on one end and a
2027 red 4-pin MicroMaTch connector on the other end.
2030 Find the USB cable that you got as part of the starter kit, and
2031 plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
2034 Take the 2 screws out of the TeleDongle case to get access
2035 to the circuit board.
2038 Plug the 8-pin end of the programming cable to the
2039 matching connector on the programmer, and the 4-pin end to the
2040 matching connector on the TeleDongle.
2041 Note that each MicroMaTch connector has an alignment pin that
2042 goes through a hole in the PC board when you have the cable
2046 Attach a battery to the TeleMetrum board if you're using one.
2049 Plug both the programmer and the TeleDongle into your computer's USB
2050 ports, and power up the programmer.
2053 Run AltosUI, and select 'Flash Image' from the File menu.
2056 Pick the programmer device from the list, identifying it as the
2060 Select the image you want put on the TeleDongle, which should have a
2061 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
2062 in the default directory, if not you may have to poke around
2063 your system to find it.
2066 Make sure the configuration parameters are reasonable
2067 looking. If the serial number and/or RF configuration
2068 values aren't right, you'll need to change them. The TeleDongle
2069 serial number is on the "bottom" of the circuit board, and can
2070 usually be read through the translucent blue plastic case without
2071 needing to remove the board from the case.
2074 Hit the 'OK' button and the software should proceed to flash
2075 the TeleDongle with new firmware, showing a progress bar.
2078 Confirm that the TeleDongle board seems to have updated OK, which you
2079 can do by plugging in to it over USB and using a terminal program
2080 to connect to the board and issue the 'v' command to check
2081 the version, etc. Once you're happy, remove the programming cable
2082 and put the cover back on the TeleDongle.
2085 If something goes wrong, give it another try.
2089 Be careful removing the programming cable from the locking 8-pin
2090 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
2091 screwdriver or knife blade to gently pry the locking ears out
2092 slightly to extract the connector. We used a locking connector on
2093 TeleMetrum to help ensure that the cabling to companion boards
2094 used in a rocket don't ever come loose accidentally in flight.
2099 <title>Hardware Specifications</title>
2101 <title>TeleMetrum Specifications</title>
2105 Recording altimeter for model rocketry.
2110 Supports dual deployment (can fire 2 ejection charges).
2115 70cm ham-band transceiver for telemetry down-link.
2120 Barometric pressure sensor good to 45k feet MSL.
2125 1-axis high-g accelerometer for motor characterization, capable of
2126 +/- 50g using default part.
2131 On-board, integrated GPS receiver with 5Hz update rate capability.
2136 On-board 1 megabyte non-volatile memory for flight data storage.
2141 USB interface for battery charging, configuration, and data recovery.
2146 Fully integrated support for Li-Po rechargeable batteries.
2151 Uses Li-Po to fire e-matches, can be modified to support
2152 optional separate pyro battery if needed.
2157 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
2163 <title>TeleMini Specifications</title>
2167 Recording altimeter for model rocketry.
2172 Supports dual deployment (can fire 2 ejection charges).
2177 70cm ham-band transceiver for telemetry down-link.
2182 Barometric pressure sensor good to 45k feet MSL.
2187 On-board 5 kilobyte non-volatile memory for flight data storage.
2192 RF interface for battery charging, configuration, and data recovery.
2197 Support for Li-Po rechargeable batteries, using an external charger.
2202 Uses Li-Po to fire e-matches, can be modified to support
2203 optional separate pyro battery if needed.
2208 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
2217 TeleMetrum seems to shut off when disconnected from the
2218 computer. Make sure the battery is adequately charged. Remember the
2219 unit will pull more power than the USB port can deliver before the
2220 GPS enters "locked" mode. The battery charges best when TeleMetrum
2224 It's impossible to stop the TeleDongle when it's in "p" mode, I have
2225 to unplug the USB cable? Make sure you have tried to "escape out" of
2226 this mode. If this doesn't work the reboot procedure for the
2227 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
2228 outgoing buffer IF your "escape out" ('~~') does not work.
2229 At this point using either 'ao-view' (or possibly
2230 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
2234 The amber LED (on the TeleMetrum) lights up when both
2235 battery and USB are connected. Does this mean it's charging?
2236 Yes, the yellow LED indicates the charging at the 'regular' rate.
2237 If the led is out but the unit is still plugged into a USB port,
2238 then the battery is being charged at a 'trickle' rate.
2241 There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
2242 That's the "pad" mode. Weak batteries might be the problem.
2243 It is also possible that the TeleMetrum is horizontal and the output
2244 is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
2245 it received a command packet which would have left it in "pad" mode.
2248 How do I save flight data?
2249 Live telemetry is written to file(s) whenever AltosUI is connected
2250 to the TeleDongle. The file area defaults to ~/TeleMetrum
2251 but is easily changed using the menus in AltosUI. The files that
2252 are written end in '.telem'. The after-flight
2253 data-dumped files will end in .eeprom and represent continuous data
2254 unlike the .telem files that are subject to losses
2255 along the RF data path.
2256 See the above instructions on what and how to save the eeprom stored
2257 data after physically retrieving your altimeter. Make sure to save
2258 the on-board data after each flight; while the TeleMetrum can store
2259 multiple flights, you never know when you'll lose the altimeter...
2263 <title>Notes for Older Software</title>
2266 Before AltosUI was written, using Altus Metrum devices required
2267 some finesse with the Linux command line. There was a limited
2268 GUI tool, ao-view, which provided functionality similar to the
2269 Monitor Flight window in AltosUI, but everything else was a
2270 fairly 80's experience. This appendix includes documentation for
2271 using that software.
2275 Both TeleMetrum and TeleDongle can be directly communicated
2276 with using USB ports. The first thing you should try after getting
2277 both units plugged into to your computer's USB port(s) is to run
2278 'ao-list' from a terminal-window to see what port-device-name each
2279 device has been assigned by the operating system.
2280 You will need this information to access the devices via their
2281 respective on-board firmware and data using other command line
2282 programs in the AltOS software suite.
2285 TeleMini can be communicated with through a TeleDongle device
2286 over the radio link. When first booted, TeleMini listens for a
2287 TeleDongle device and if it receives a packet, it goes into
2288 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
2289 launched. The easiest way to get it talking is to start the
2290 communication link on the TeleDongle and the power up the
2294 To access the device's firmware for configuration you need a terminal
2295 program such as you would use to talk to a modem. The software
2296 authors prefer using the program 'cu' which comes from the UUCP package
2297 on most Unix-like systems such as Linux. An example command line for
2298 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
2299 indicated from running the
2300 ao-list program. Another reasonable terminal program for Linux is
2301 'cutecom'. The default 'escape'
2302 character used by CU (i.e. the character you use to
2303 issue commands to cu itself instead of sending the command as input
2304 to the connected device) is a '~'. You will need this for use in
2305 only two different ways during normal operations. First is to exit
2306 the program by sending a '~.' which is called a 'escape-disconnect'
2307 and allows you to close-out from 'cu'. The
2308 second use will be outlined later.
2311 All of the Altus Metrum devices share the concept of a two level
2312 command set in their firmware.
2313 The first layer has several single letter commands. Once
2314 you are using 'cu' (or 'cutecom') sending (typing) a '?'
2315 returns a full list of these
2316 commands. The second level are configuration sub-commands accessed
2317 using the 'c' command, for
2318 instance typing 'c?' will give you this second level of commands
2319 (all of which require the
2320 letter 'c' to access). Please note that most configuration options
2321 are stored only in Flash memory; TeleDongle doesn't provide any storage
2322 for these options and so they'll all be lost when you unplug it.
2325 Try setting these configuration ('c' or second level menu) values. A good
2326 place to start is by setting your call sign. By default, the boards
2327 use 'N0CALL' which is cute, but not exactly legal!
2328 Spend a few minutes getting comfortable with the units, their
2329 firmware, and 'cu' (or possibly 'cutecom').
2330 For instance, try to send
2331 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
2332 Verify you can connect and disconnect from the units while in your
2333 terminal program by sending the escape-disconnect mentioned above.
2336 To set the radio frequency, use the 'c R' command to specify the
2337 radio transceiver configuration parameter. This parameter is computed
2338 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
2339 the standard calibration reference frequency, 'S', (normally 434.550MHz):
2343 Round the result to the nearest integer value.
2344 As with all 'c' sub-commands, follow this with a 'c w' to write the
2345 change to the parameter block in the on-board flash on
2346 your altimeter board if you want the change to stay in place across reboots.
2349 To set the apogee delay, use the 'c d' command.
2350 As with all 'c' sub-commands, follow this with a 'c w' to write the
2351 change to the parameter block in the on-board DataFlash chip.
2354 To set the main deployment altitude, use the 'c m' command.
2355 As with all 'c' sub-commands, follow this with a 'c w' to write the
2356 change to the parameter block in the on-board DataFlash chip.
2359 To calibrate the radio frequency, connect the UHF antenna port to a
2360 frequency counter, set the board to 434.550MHz, and use the 'C'
2361 command to generate a CW carrier. Wait for the transmitter temperature
2362 to stabilize and the frequency to settle down.
2363 Then, divide 434.550 MHz by the
2364 measured frequency and multiply by the current radio cal value show
2365 in the 'c s' command. For an unprogrammed board, the default value
2366 is 1186611. Take the resulting integer and program it using the 'c f'
2367 command. Testing with the 'C' command again should show a carrier
2368 within a few tens of Hertz of the intended frequency.
2369 As with all 'c' sub-commands, follow this with a 'c w' to write the
2370 change to the parameter block in the on-board DataFlash chip.
2373 Note that the 'reboot' command, which is very useful on the altimeters,
2374 will likely just cause problems with the dongle. The *correct* way
2375 to reset the dongle is just to unplug and re-plug it.
2378 A fun thing to do at the launch site and something you can do while
2379 learning how to use these units is to play with the radio link access
2380 between an altimeter and the TeleDongle. Be aware that you *must* create
2381 some physical separation between the devices, otherwise the link will
2382 not function due to signal overload in the receivers in each device.
2385 Now might be a good time to take a break and read the rest of this
2386 manual, particularly about the two "modes" that the altimeters
2387 can be placed in. TeleMetrum uses the position of the device when booting
2388 up will determine whether the unit is in "pad" or "idle" mode. TeleMini
2389 enters "idle" mode when it receives a command packet within the first 5 seconds
2390 of being powered up, otherwise it enters "pad" mode.
2393 You can access an altimeter in idle mode from the TeleDongle's USB
2394 connection using the radio link
2395 by issuing a 'p' command to the TeleDongle. Practice connecting and
2396 disconnecting ('~~' while using 'cu') from the altimeter. If
2397 you cannot escape out of the "p" command, (by using a '~~' when in
2398 CU) then it is likely that your kernel has issues. Try a newer version.
2401 Using this radio link allows you to configure the altimeter, test
2402 fire e-matches and igniters from the flight line, check pyro-match
2403 continuity and so forth. You can leave the unit turned on while it
2404 is in 'idle mode' and then place the
2405 rocket vertically on the launch pad, walk away and then issue a
2406 reboot command. The altimeter will reboot and start sending data
2407 having changed to the "pad" mode. If the TeleDongle is not receiving
2408 this data, you can disconnect 'cu' from the TeleDongle using the
2409 procedures mentioned above and THEN connect to the TeleDongle from
2410 inside 'ao-view'. If this doesn't work, disconnect from the
2411 TeleDongle, unplug it, and try again after plugging it back in.
2414 In order to reduce the chance of accidental firing of pyrotechnic
2415 charges, the command to fire a charge is intentionally somewhat
2416 difficult to type, and the built-in help is slightly cryptic to
2417 prevent accidental echoing of characters from the help text back at
2418 the board from firing a charge. The command to fire the apogee
2419 drogue charge is 'i DoIt drogue' and the command to fire the main
2420 charge is 'i DoIt main'.
2423 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
2424 and 'ao-view' will both auditorily announce and visually indicate
2426 Now you can launch knowing that you have a good data path and
2427 good satellite lock for flight data and recovery. Remember
2428 you MUST tell ao-view to connect to the TeleDongle explicitly in
2429 order for ao-view to be able to receive data.
2432 The altimeters provide RDF (radio direction finding) tones on
2433 the pad, during descent and after landing. These can be used to
2434 locate the rocket using a directional antenna; the signal
2435 strength providing an indication of the direction from receiver to rocket.
2438 TeleMetrum also provides GPS tracking data, which can further simplify
2439 locating the rocket once it has landed. (The last good GPS data
2440 received before touch-down will be on the data screen of 'ao-view'.)
2443 Once you have recovered the rocket you can download the eeprom
2444 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
2445 either a USB cable or over the radio link using TeleDongle.
2446 And by following the man page for 'ao-postflight' you can create
2447 various data output reports, graphs, and even KML data to see the
2448 flight trajectory in Google-earth. (Moving the viewing angle making
2449 sure to connect the yellow lines while in Google-earth is the proper
2453 As for ao-view.... some things are in the menu but don't do anything
2454 very useful. The developers have stopped working on ao-view to focus
2455 on a new, cross-platform ground station program. So ao-view may or
2456 may not be updated in the future. Mostly you just use
2457 the Log and Device menus. It has a wonderful display of the incoming
2458 flight data and I am sure you will enjoy what it has to say to you
2459 once you enable the voice output!
2463 <title>Calibration</title>
2465 There are only two calibrations required for a TeleMetrum board, and
2466 only one for TeleDongle and TeleMini. All boards are shipped from
2467 the factory pre-calibrated, but the procedures are documented here
2468 in case they are ever needed. Re-calibration is not supported by
2469 AltosUI, you must connect to the board with a serial terminal program
2470 and interact directly with the on-board command interpreter to effect
2474 <title>Radio Frequency</title>
2476 The radio frequency is synthesized from a clock based on the 48 MHz
2477 crystal on the board. The actual frequency of this oscillator
2478 must be measured to generate a calibration constant. While our
2480 bandwidth is wide enough to allow boards to communicate even when
2481 their oscillators are not on exactly the same frequency, performance
2482 is best when they are closely matched.
2483 Radio frequency calibration requires a calibrated frequency counter.
2484 Fortunately, once set, the variation in frequency due to aging and
2485 temperature changes is small enough that re-calibration by customers
2486 should generally not be required.
2489 To calibrate the radio frequency, connect the UHF antenna port to a
2490 frequency counter, set the board to 434.550MHz, and use the 'C'
2491 command in the on-board command interpreter to generate a CW
2492 carrier. For TeleMetrum, this is best done over USB. For TeleMini,
2493 note that the only way to escape the 'C' command is via power cycle
2494 since the board will no longer be listening for commands once it
2495 starts generating a CW carrier.
2498 Wait for the transmitter temperature to stabilize and the frequency
2499 to settle down. Then, divide 434.550 MHz by the
2500 measured frequency and multiply by the current radio cal value show
2501 in the 'c s' command. For an unprogrammed board, the default value
2502 is 1186611. Take the resulting integer and program it using the 'c f'
2503 command. Testing with the 'C' command again should show a carrier
2504 within a few tens of Hertz of the intended frequency.
2505 As with all 'c' sub-commands, follow this with a 'c w' to write the
2506 change to the parameter block in the on-board DataFlash chip.
2509 Note that any time you re-do the radio frequency calibration, the
2510 radio frequency is reset to the default 434.550 Mhz. If you want
2511 to use another frequency, you will have to set that again after
2512 calibration is completed.
2516 <title>TeleMetrum Accelerometer</title>
2518 The TeleMetrum accelerometer we use has its own 5 volt power
2520 the output must be passed through a resistive voltage divider to match
2521 the input of our 3.3 volt ADC. This means that unlike the barometric
2522 sensor, the output of the acceleration sensor is not ratio-metric to
2523 the ADC converter, and calibration is required. Explicitly
2524 calibrating the accelerometers also allows us to load any device
2525 from a Freescale family that includes at least +/- 40g, 50g, 100g,
2526 and 200g parts. Using gravity,
2527 a simple 2-point calibration yields acceptable results capturing both
2528 the different sensitivities and ranges of the different accelerometer
2529 parts and any variation in power supply voltages or resistor values
2530 in the divider network.
2533 To calibrate the acceleration sensor, use the 'c a 0' command. You
2534 will be prompted to orient the board vertically with the UHF antenna
2535 up and press a key, then to orient the board vertically with the
2536 UHF antenna down and press a key. Note that the accuracy of this
2537 calibration depends primarily on how perfectly vertical and still
2538 the board is held during the cal process. As with all 'c'
2539 sub-commands, follow this with a 'c w' to write the
2540 change to the parameter block in the on-board DataFlash chip.
2543 The +1g and -1g calibration points are included in each telemetry
2544 frame and are part of the header stored in onboard flash to be
2545 downloaded after flight. We always store and return raw ADC
2546 samples for each sensor... so nothing is permanently "lost" or
2547 "damaged" if the calibration is poor.
2550 In the unlikely event an accel cal goes badly, it is possible
2551 that TeleMetrum may always come up in 'pad mode' and as such not be
2552 listening to either the USB or radio link. If that happens,
2553 there is a special hook in the firmware to force the board back
2554 in to 'idle mode' so you can re-do the cal. To use this hook, you
2555 just need to ground the SPI clock pin at power-on. This pin is
2556 available as pin 2 on the 8-pin companion connector, and pin 1 is
2557 ground. So either carefully install a fine-gauge wire jumper
2558 between the two pins closest to the index hole end of the 8-pin
2559 connector, or plug in the programming cable to the 8-pin connector
2560 and use a small screwdriver or similar to short the two pins closest
2561 to the index post on the 4-pin end of the programming cable, and
2562 power up the board. It should come up in 'idle mode' (two beeps),
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2579 <!-- LocalWords: Altusmetrum
projects / fw / altos / blob