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2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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5 <title>TeleMetrum</title>
6 <subtitle>Owner's Manual for the TeleMetrum System</subtitle>
9 <firstname>Bdale</firstname>
10 <surname>Garbee</surname>
13 <firstname>Keith</firstname>
14 <surname>Packard</surname>
18 <holder>Bdale Garbee and Keith Packard</holder>
22 This document is released under the terms of the
23 <ulink url="http://creativecommons.org/licenses/by-sa/3.0/">
24 Creative Commons ShareAlike 3.0
31 <revnumber>0.3</revnumber>
32 <date>12 November 2010</date>
34 Add instructions for re-flashing devices using AltosUI
38 <revnumber>0.2</revnumber>
39 <date>18 July 2010</date>
40 <revremark>Significant update</revremark>
43 <revnumber>0.1</revnumber>
44 <date>30 March 2010</date>
45 <revremark>Initial content</revremark>
50 <title>Introduction and Overview</title>
52 Welcome to the Altus Metrum community! Our circuits and software reflect
53 our passion for both hobby rocketry and Free Software. We hope their
54 capabilities and performance will delight you in every way, but by
55 releasing all of our hardware and software designs under open licenses,
56 we also hope to empower you to take as active a role in our collective
60 The focal point of our community is TeleMetrum, a dual deploy altimeter
61 with fully integrated GPS and radio telemetry as standard features, and
62 a "companion interface" that will support optional capabilities in the
66 Complementing TeleMetrum is TeleDongle, a USB to RF interface for
67 communicating with TeleMetrum. Combined with your choice of antenna and
68 notebook computer, TeleDongle and our associated user interface software
69 form a complete ground station capable of logging and displaying in-flight
70 telemetry, aiding rocket recovery, then processing and archiving flight
71 data for analysis and review.
74 More products will be added to the Altus Metrum family over time, and
75 we currently envision that this will evolve to be be the single,
76 comprehensive manual for the entire product family.
80 <title>Getting Started</title>
82 This chapter began as "The Mere-Mortals Quick Start/Usage Guide to
83 the Altus Metrum Starter Kit" by Bob Finch, W9YA, NAR 12965, TRA 12350,
84 w9ya@amsat.org. Bob was one of our first customers for a production
85 TeleMetrum, and the enthusiasm that led to his contribution of this
86 section is immensely gratifying and highy appreciated!
89 The first thing to do after you check the inventory of parts in your
90 "starter kit" is to charge the battery by plugging it into the
91 corresponding socket of the TeleMetrum and then using the USB A to mini
92 B cable to plug the Telemetrum into your computer's USB socket. The
93 TeleMetrum circuitry will charge the battery whenever it is plugged
94 in, because the TeleMetrum's on-off switch does NOT control the
95 charging circuitry. When the GPS chip is initially searching for
96 satellites, TeleMetrum will consume more current than it can pull
97 from the usb port, so the battery must be attached in order to get
98 satellite lock. Once GPS is locked, the current consumption goes back
99 down enough to enable charging while
100 running. So it's a good idea to fully charge the battery as your
101 first item of business so there is no issue getting and maintaining
102 satellite lock. The yellow charge indicator led will go out when the
103 battery is nearly full and the charger goes to trickle charge. It
104 can take several hours to fully recharge a deeply discharged battery.
107 The other active device in the starter kit is the TeleDongle USB to
108 RF interface. If you plug it in to your Mac or Linux computer it should
109 "just work", showing up as a serial port device. Windows systems need
110 driver information that is part of the AltOS download to know that the
111 existing USB modem driver will work. If you are using Linux and are
112 having problems, try moving to a fresher kernel (2.6.33 or newer), as
113 the USB serial driver had ugly bugs in some earlier versions.
116 Next you should obtain and install the AltOS utilities. These include
117 the AltosUI ground station program, current firmware images for
118 TeleMetrum and TeleDongle, and a number of standalone utilities that
119 are rarely needed. Pre-built binary packages are available for Debian
120 Linux, Microsoft Windows, and recent MacOSX versions. Full sourcecode
121 and build instructions for some other Linux variants are also available.
122 The latest version may always be downloaded from
123 http://altusmetrum.org/AltOS.
126 Both Telemetrum and TeleDongle can be directly communicated
127 with using USB ports. The first thing you should try after getting
128 both units plugged into to your computer's usb port(s) is to run
129 'ao-list' from a terminal-window to see what port-device-name each
130 device has been assigned by the operating system.
131 You will need this information to access the devices via their
132 respective on-board firmware and data using other command line
133 programs in the AltOS software suite.
136 To access the device's firmware for configuration you need a terminal
137 program such as you would use to talk to a modem. The software
138 authors prefer using the program 'cu' which comes from the UUCP package
139 on most Unix-like systems such as Linux. An example command line for
140 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
141 indicated from running the
142 ao-list program. Another reasonable terminal program for Linux is
143 'cutecom'. The default 'escape'
144 character used by CU (i.e. the character you use to
145 issue commands to cu itself instead of sending the command as input
146 to the connected device) is a '~'. You will need this for use in
147 only two different ways during normal operations. First is to exit
148 the program by sending a '~.' which is called a 'escape-disconnect'
149 and allows you to close-out from 'cu'. The
150 second use will be outlined later.
153 Both TeleMetrum and TeleDongle share the concept of a two level
154 command set in their firmware.
155 The first layer has several single letter commands. Once
156 you are using 'cu' (or 'cutecom') sending (typing) a '?'
157 returns a full list of these
158 commands. The second level are configuration sub-commands accessed
159 using the 'c' command, for
160 instance typing 'c?' will give you this second level of commands
161 (all of which require the
162 letter 'c' to access). Please note that most configuration options
163 are stored only in DataFlash memory, and only TeleMetrum has this
164 memory to save the various values entered like the channel number
165 and your callsign when powered off. TeleDongle requires that you
166 set these each time you plug it in, which ao-view can help with.
169 Try setting these config ('c' or second level menu) values. A good
170 place to start is by setting your call sign. By default, the boards
171 use 'N0CALL' which is cute, but not exactly legal!
172 Spend a few minutes getting comfortable with the units, their
173 firmware, and 'cu' (or possibly 'cutecom').
174 For instance, try to send
175 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
176 Verify you can connect and disconnect from the units while in your
177 terminal program by sending the escape-disconnect mentioned above.
180 Note that the 'reboot' command, which is very useful on TeleMetrum,
181 will likely just cause problems with the dongle. The *correct* way
182 to reset the dongle is just to unplug and re-plug it.
185 A fun thing to do at the launch site and something you can do while
186 learning how to use these units is to play with the rf-link access
187 of the TeleMetrum from the TeleDongle. Be aware that you *must* create
188 some physical separation between the devices, otherwise the link will
189 not function due to signal overload in the receivers in each device.
192 Now might be a good time to take a break and read the rest of this
193 manual, particularly about the two "modes" that the TeleMetrum
194 can be placed in and how the position of the TeleMetrum when booting
195 up will determine whether the unit is in "pad" or "idle" mode.
198 You can access a TeleMetrum in idle mode from the Teledongle's USB
199 connection using the rf link
200 by issuing a 'p' command to the TeleDongle. Practice connecting and
201 disconnecting ('~~' while using 'cu') from the TeleMetrum. If
202 you cannot escape out of the "p" command, (by using a '~~' when in
203 CU) then it is likely that your kernel has issues. Try a newer version.
206 Using this rf link allows you to configure the TeleMetrum, test
207 fire e-matches and igniters from the flight line, check pyro-match
208 continuity and so forth. You can leave the unit turned on while it
209 is in 'idle mode' and then place the
210 rocket vertically on the launch pad, walk away and then issue a
211 reboot command. The TeleMetrum will reboot and start sending data
212 having changed to the "pad" mode. If the TeleDongle is not receiving
213 this data, you can disconnect 'cu' from the Teledongle using the
214 procedures mentioned above and THEN connect to the TeleDongle from
215 inside 'ao-view'. If this doesn't work, disconnect from the
216 TeleDongle, unplug it, and try again after plugging it back in.
219 Eventually the GPS will find enough satellites, lock in on them,
220 and 'ao-view' will both auditorially announce and visually indicate
222 Now you can launch knowing that you have a good data path and
223 good satellite lock for flight data and recovery. Remember
224 you MUST tell ao-view to connect to the TeleDongle explicitly in
225 order for ao-view to be able to receive data.
228 Both RDF (radio direction finding) tones from the TeleMetrum and
229 GPS trekking data are available and together are very useful in
230 locating the rocket once it has landed. (The last good GPS data
231 received before touch-down will be on the data screen of 'ao-view'.)
234 Once you have recovered the rocket you can download the eeprom
235 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
236 either a USB cable or over the radio link using TeleDongle.
237 And by following the man page for 'ao-postflight' you can create
238 various data output reports, graphs, and even kml data to see the
239 flight trajectory in google-earth. (Moving the viewing angle making
240 sure to connect the yellow lines while in google-earth is the proper
244 As for ao-view.... some things are in the menu but don't do anything
245 very useful. The developers have stopped working on ao-view to focus
246 on a new, cross-platform ground station program. So ao-view may or
247 may not be updated in the future. Mostly you just use
248 the Log and Device menus. It has a wonderful display of the incoming
249 flight data and I am sure you will enjoy what it has to say to you
250 once you enable the voice output!
255 The altimeter (TeleMetrum) seems to shut off when disconnected from the
256 computer. Make sure the battery is adequately charged. Remember the
257 unit will pull more power than the USB port can deliver before the
258 GPS enters "locked" mode. The battery charges best when TeleMetrum
262 It's impossible to stop the TeleDongle when it's in "p" mode, I have
263 to unplug the USB cable? Make sure you have tried to "escape out" of
264 this mode. If this doesn't work the reboot procedure for the
265 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
266 outgoing buffer IF your "escape out" ('~~') does not work.
267 At this point using either 'ao-view' (or possibly
268 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
272 The amber LED (on the TeleMetrum/altimeter) lights up when both
273 battery and USB are connected. Does this mean it's charging?
274 Yes, the yellow LED indicates the charging at the 'regular' rate.
275 If the led is out but the unit is still plugged into a USB port,
276 then the battery is being charged at a 'trickle' rate.
279 There are no "dit-dah-dah-dit" sound like the manual mentions?
280 That's the "pad" mode. Weak batteries might be the problem.
281 It is also possible that the unit is horizontal and the output
282 is instead a "dit-dit" meaning 'idle'.
285 It's unclear how to use 'ao-view' and other programs when 'cu'
286 is running. You cannot have more than one program connected to
287 the TeleDongle at one time without apparent data loss as the
288 incoming data will not make it to both programs intact.
289 Disconnect whatever programs aren't currently being used.
292 How do I save flight data?
293 Live telemetry is written to file(s) whenever 'ao-view' is connected
294 to the TeleDongle. The file area defaults to ~/altos
295 but is easily changed using the menus in 'ao-view'. The files that
296 are written end in '.telem'. The after-flight
297 data-dumped files will end in .eeprom and represent continuous data
298 unlike the rf-linked .telem files that are subject to the
299 turnarounds/data-packaging time slots in the half-duplex rf data path.
300 See the above instructions on what and how to save the eeprom stored
301 data after physically retrieving your TeleMetrum. Make sure to save
302 the on-board data after each flight, as the current firmware will
303 over-write any previous flight data during a new flight.
308 <title>Specifications</title>
312 Recording altimeter for model rocketry.
317 Supports dual deployment (can fire 2 ejection charges).
322 70cm ham-band transceiver for telemetry downlink.
327 Barometric pressure sensor good to 45k feet MSL.
332 1-axis high-g accelerometer for motor characterization, capable of
333 +/- 50g using default part.
338 On-board, integrated GPS receiver with 5hz update rate capability.
343 On-board 1 megabyte non-volatile memory for flight data storage.
348 USB interface for battery charging, configuration, and data recovery.
353 Fully integrated support for LiPo rechargeable batteries.
358 Uses LiPo to fire e-matches, support for optional separate pyro
364 2.75 x 1 inch board designed to fit inside 29mm airframe coupler tube.
370 <title>Handling Precautions</title>
372 TeleMetrum is a sophisticated electronic device. When handled gently and
373 properly installed in an airframe, it will deliver impressive results.
374 However, like all electronic devices, there are some precautions you
378 The Lithium Polymer rechargeable batteries used with TeleMetrum have an
379 extraordinary power density. This is great because we can fly with
380 much less battery mass than if we used alkaline batteries or previous
381 generation rechargeable batteries... but if they are punctured
382 or their leads are allowed to short, they can and will release their
384 Thus we recommend that you take some care when handling our batteries
385 and consider giving them some extra protection in your airframe. We
386 often wrap them in suitable scraps of closed-cell packing foam before
387 strapping them down, for example.
390 The TeleMetrum barometric sensor is sensitive to sunlight. In normal
391 mounting situations, it and all of the other surface mount components
392 are "down" towards whatever the underlying mounting surface is, so
393 this is not normally a problem. Please consider this, though, when
394 designing an installation, for example, in a 29mm airframe with a
395 see-through plastic payload bay.
398 The TeleMetrum barometric sensor sampling port must be able to
400 both by not being covered by foam or tape or other materials that might
401 directly block the hole on the top of the sensor, but also by having a
402 suitable static vent to outside air.
405 As with all other rocketry electronics, TeleMetrum must be protected
406 from exposure to corrosive motor exhaust and ejection charge gasses.
410 <title>Hardware Overview</title>
412 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
413 fit inside coupler for 29mm airframe tubing, but using it in a tube that
414 small in diameter may require some creativity in mounting and wiring
415 to succeed! The default 1/4
416 wave UHF wire antenna attached to the center of the nose-cone end of
417 the board is about 7 inches long, and wiring for a power switch and
418 the e-matches for apogee and main ejection charges depart from the
419 fin can end of the board. Given all this, an ideal "simple" avionics
420 bay for TeleMetrum should have at least 10 inches of interior length.
423 A typical TeleMetrum installation using the on-board GPS antenna and
424 default wire UHF antenna involves attaching only a suitable
425 Lithium Polymer battery, a single pole switch for power on/off, and
426 two pairs of wires connecting e-matches for the apogee and main ejection
430 By default, we use the unregulated output of the LiPo battery directly
431 to fire ejection charges. This works marvelously with standard
432 low-current e-matches like the J-Tek from MJG Technologies, and with
433 Quest Q2G2 igniters. However, if you
434 want or need to use a separate pyro battery, you can do so by adding
435 a second 2mm connector to position B2 on the board and cutting the
436 thick pcb trace connecting the LiPo battery to the pyro circuit between
437 the two silk screen marks on the surface mount side of the board shown
441 We offer two choices of pyro and power switch connector, or you can
442 choose neither and solder wires directly to the board. All three choices
443 are reasonable depending on the constraints of your airframe. Our
444 favorite option when there is sufficient room above the board is to use
445 the Tyco pin header with polarization and locking. If you choose this
446 option, you crimp individual wires for the power switch and e-matches
447 into a mating connector, and installing and removing the TeleMetrum
448 board from an airframe is as easy as plugging or unplugging two
449 connectors. If the airframe will not support this much height or if
450 you want to be able to directly attach e-match leads to the board, we
451 offer a screw terminal block. This is very similar to what most other
452 altimeter vendors provide and so may be the most familiar option.
453 You'll need a very small straight blade screwdriver to connect
454 and disconnect the board in this case, such as you might find in a
455 jeweler's screwdriver set. Finally, you can forego both options and
456 solder wires directly to the board, which may be the best choice for
457 minimum diameter and/or minimum mass designs.
460 For most airframes, the integrated GPS antenna and wire UHF antenna are
461 a great combination. However, if you are installing in a carbon-fiber
462 electronics bay which is opaque to RF signals, you may need to use
463 off-board external antennas instead. In this case, you can order
464 TeleMetrum with an SMA connector for the UHF antenna connection, and
465 you can unplug the integrated GPS antenna and select an appropriate
466 off-board GPS antenna with cable terminating in a U.FL connector.
470 <title>Operation</title>
472 <title>Firmware Modes </title>
474 The AltOS firmware build for TeleMetrum has two fundamental modes,
475 "idle" and "flight". Which of these modes the firmware operates in
476 is determined by the orientation of the rocket (well, actually the
477 board, of course...) at the time power is switched on. If the rocket
478 is "nose up", then TeleMetrum assumes it's on a rail or rod being
479 prepared for launch, so the firmware chooses flight mode. However,
480 if the rocket is more or less horizontal, the firmware instead enters
484 At power on, you will hear three beeps
485 ("S" in Morse code for startup) and then a pause while
486 TeleMetrum completes initialization and self tests, and decides which
490 In flight or "pad" mode, TeleMetrum turns on the GPS system,
492 state machine, goes into transmit-only mode on the RF link sending
493 telemetry, and waits for launch to be detected. Flight mode is
494 indicated by an audible "di-dah-dah-dit" ("P" for pad) on the
496 beeps indicating the state of the pyrotechnic igniter continuity.
497 One beep indicates apogee continuity, two beeps indicate
498 main continuity, three beeps indicate both apogee and main continuity,
499 and one longer "brap" sound indicates no continuity. For a dual
500 deploy flight, make sure you're getting three beeps before launching!
501 For apogee-only or motor eject flights, do what makes sense.
504 In idle mode, you will hear an audible "di-dit" ("I" for idle), and
505 the normal flight state machine is disengaged, thus
506 no ejection charges will fire. TeleMetrum also listens on the RF
507 link when in idle mode for packet mode requests sent from TeleDongle.
508 Commands can be issued to a TeleMetrum in idle mode over either
509 USB or the RF link equivalently.
510 Idle mode is useful for configuring TeleMetrum, for extracting data
511 from the on-board storage chip after flight, and for ground testing
515 One "neat trick" of particular value when TeleMetrum is used with very
516 large airframes, is that you can power the board up while the rocket
517 is horizontal, such that it comes up in idle mode. Then you can
518 raise the airframe to launch position, use a TeleDongle to open
519 a packet connection, and issue a 'reset' command which will cause
520 TeleMetrum to reboot, realize it's now nose-up, and thus choose
521 flight mode. This is much safer than standing on the top step of a
522 rickety step-ladder or hanging off the side of a launch tower with
523 a screw-driver trying to turn on your avionics before installing
530 TeleMetrum includes a complete GPS receiver. See a later section for
531 a brief explanation of how GPS works that will help you understand
532 the information in the telemetry stream. The bottom line is that
533 the TeleMetrum GPS receiver needs to lock onto at least four
534 satellites to obtain a solid 3 dimensional position fix and know
538 TeleMetrum provides backup power to the GPS chip any time a LiPo
539 battery is connected. This allows the receiver to "warm start" on
540 the launch rail much faster than if every power-on were a "cold start"
541 for the GPS receiver. In typical operations, powering up TeleMetrum
542 on the flight line in idle mode while performing final airframe
543 preparation will be sufficient to allow the GPS receiver to cold
544 start and acquire lock. Then the board can be powered down during
545 RSO review and installation on a launch rod or rail. When the board
546 is turned back on, the GPS system should lock very quickly, typically
547 long before igniter installation and return to the flight line are
552 <title>Ground Testing </title>
554 An important aspect of preparing a rocket using electronic deployment
555 for flight is ground testing the recovery system. Thanks
556 to the bi-directional RF link central to the Altus Metrum system,
557 this can be accomplished in a TeleMetrum-equipped rocket without as
558 much work as you may be accustomed to with other systems. It can
562 Just prep the rocket for flight, then power up TeleMetrum while the
563 airframe is horizontal. This will cause the firmware to go into
564 "idle" mode, in which the normal flight state machine is disabled and
565 charges will not fire without manual command. Then, establish an
566 RF packet connection from a TeleDongle-equipped computer using the
567 P command from a safe distance. You can now command TeleMetrum to
568 fire the apogee or main charges to complete your testing.
571 In order to reduce the chance of accidental firing of pyrotechnic
572 charges, the command to fire a charge is intentionally somewhat
573 difficult to type, and the built-in help is slightly cryptic to
574 prevent accidental echoing of characters from the help text back at
575 the board from firing a charge. The command to fire the apogee
576 drogue charge is 'i DoIt drogue' and the command to fire the main
577 charge is 'i DoIt main'.
581 <title>Radio Link </title>
583 The chip our boards are based on incorporates an RF transceiver, but
584 it's not a full duplex system... each end can only be transmitting or
585 receiving at any given moment. So we had to decide how to manage the
589 By design, TeleMetrum firmware listens for an RF connection when
590 it's in "idle mode" (turned on while the rocket is horizontal), which
591 allows us to use the RF link to configure the rocket, do things like
592 ejection tests, and extract data after a flight without having to
593 crack open the airframe. However, when the board is in "flight
594 mode" (turned on when the rocket is vertical) the TeleMetrum only
595 transmits and doesn't listen at all. That's because we want to put
596 ultimate priority on event detection and getting telemetry out of
597 the rocket and out over
598 the RF link in case the rocket crashes and we aren't able to extract
602 We don't use a 'normal packet radio' mode because they're just too
603 inefficient. The GFSK modulation we use is just FSK with the
604 baseband pulses passed through a
605 Gaussian filter before they go into the modulator to limit the
606 transmitted bandwidth. When combined with the hardware forward error
607 correction support in the cc1111 chip, this allows us to have a very
608 robust 38.4 kilobit data link with only 10 milliwatts of transmit power,
609 a whip antenna in the rocket, and a hand-held Yagi on the ground. We've
610 had flights to above 21k feet AGL with good reception, and calculations
611 suggest we should be good to well over 40k feet AGL with a 5-element yagi on
612 the ground. We hope to fly boards to higher altitudes soon, and would
613 of course appreciate customer feedback on performance in higher
618 <title>Configurable Parameters</title>
620 Configuring a TeleMetrum board for flight is very simple. Because we
621 have both acceleration and pressure sensors, there is no need to set
622 a "mach delay", for example. The few configurable parameters can all
623 be set using a simple terminal program over the USB port or RF link
627 <title>Radio Channel</title>
629 Our firmware supports 10 channels. The default channel 0 corresponds
630 to a center frequency of 434.550 Mhz, and channels are spaced every
631 100 khz. Thus, channel 1 is 434.650 Mhz, and channel 9 is 435.550 Mhz.
632 At any given launch, we highly recommend coordinating who will use
633 each channel and when to avoid interference. And of course, both
634 TeleMetrum and TeleDongle must be configured to the same channel to
635 successfully communicate with each other.
638 To set the radio channel, use the 'c r' command, like 'c r 3' to set
640 As with all 'c' sub-commands, follow this with a 'c w' to write the
641 change to the parameter block in the on-board DataFlash chip on
642 your TeleMetrum board if you want the change to stay in place across reboots.
646 <title>Apogee Delay</title>
648 Apogee delay is the number of seconds after TeleMetrum detects flight
649 apogee that the drogue charge should be fired. In most cases, this
650 should be left at the default of 0. However, if you are flying
651 redundant electronics such as for an L3 certification, you may wish
652 to set one of your altimeters to a positive delay so that both
653 primary and backup pyrotechnic charges do not fire simultaneously.
656 To set the apogee delay, use the [FIXME] command.
657 As with all 'c' sub-commands, follow this with a 'c w' to write the
658 change to the parameter block in the on-board DataFlash chip.
661 Please note that the TeleMetrum apogee detection algorithm always
662 fires a fraction of a second *after* apogee. If you are also flying
663 an altimeter like the PerfectFlite MAWD, which only supports selecting
664 0 or 1 seconds of apogee delay, you may wish to set the MAWD to 0
665 seconds delay and set the TeleMetrum to fire your backup 2 or 3
666 seconds later to avoid any chance of both charges firing
667 simultaneously. We've flown several airframes this way quite happily,
668 including Keith's successful L3 cert.
672 <title>Main Deployment Altitude</title>
674 By default, TeleMetrum will fire the main deployment charge at an
675 elevation of 250 meters (about 820 feet) above ground. We think this
676 is a good elevation for most airframes, but feel free to change this
677 to suit. In particular, if you are flying two altimeters, you may
679 deployment elevation for the backup altimeter to be something lower
680 than the primary so that both pyrotechnic charges don't fire
684 To set the main deployment altitude, use the [FIXME] command.
685 As with all 'c' sub-commands, follow this with a 'c w' to write the
686 change to the parameter block in the on-board DataFlash chip.
691 <title>Calibration</title>
693 There are only two calibrations required for a TeleMetrum board, and
694 only one for TeleDongle.
697 <title>Radio Frequency</title>
699 The radio frequency is synthesized from a clock based on the 48 Mhz
700 crystal on the board. The actual frequency of this oscillator must be
701 measured to generate a calibration constant. While our GFSK modulation
702 bandwidth is wide enough to allow boards to communicate even when
703 their oscillators are not on exactly the same frequency, performance
704 is best when they are closely matched.
705 Radio frequency calibration requires a calibrated frequency counter.
706 Fortunately, once set, the variation in frequency due to aging and
707 temperature changes is small enough that re-calibration by customers
708 should generally not be required.
711 To calibrate the radio frequency, connect the UHF antenna port to a
712 frequency counter, set the board to channel 0, and use the 'C'
713 command to generate a CW carrier. Wait for the transmitter temperature
714 to stabilize and the frequency to settle down.
715 Then, divide 434.550 Mhz by the
716 measured frequency and multiply by the current radio cal value show
717 in the 'c s' command. For an unprogrammed board, the default value
718 is 1186611. Take the resulting integer and program it using the 'c f'
719 command. Testing with the 'C' command again should show a carrier
720 within a few tens of Hertz of the intended frequency.
721 As with all 'c' sub-commands, follow this with a 'c w' to write the
722 change to the parameter block in the on-board DataFlash chip.
726 <title>Accelerometer</title>
728 The accelerometer we use has its own 5 volt power supply and
729 the output must be passed through a resistive voltage divider to match
730 the input of our 3.3 volt ADC. This means that unlike the barometric
731 sensor, the output of the acceleration sensor is not ratiometric to
732 the ADC converter, and calibration is required. We also support the
733 use of any of several accelerometers from a Freescale family that
734 includes at least +/- 40g, 50g, 100g, and 200g parts. Using gravity,
735 a simple 2-point calibration yields acceptable results capturing both
736 the different sensitivities and ranges of the different accelerometer
737 parts and any variation in power supply voltages or resistor values
738 in the divider network.
741 To calibrate the acceleration sensor, use the 'c a 0' command. You
742 will be prompted to orient the board vertically with the UHF antenna
743 up and press a key, then to orient the board vertically with the
744 UHF antenna down and press a key.
745 As with all 'c' sub-commands, follow this with a 'c w' to write the
746 change to the parameter block in the on-board DataFlash chip.
749 The +1g and -1g calibration points are included in each telemetry
750 frame and are part of the header extracted by ao-dumplog after flight.
751 Note that we always store and return raw ADC samples for each
752 sensor... nothing is permanently "lost" or "damaged" if the
759 <title>Updating Device Firmware</title>
761 The big conceptual thing to realize is that you have to use a
762 TeleDongle as a programmer to update a TeleMetrum, and vice versa.
763 Due to limited memory resources in the cc1111, we don't support
764 programming either unit directly over USB.
767 You may wish to begin by ensuring you have current firmware images.
768 These are distributed as part of the AltOS software bundle that
769 also includes the AltosUI ground station program. Newer ground
770 station versions typically work fine with older firmware versions,
771 so you don't need to update your devices just to try out new
772 software features. You can always download the most recent
773 version from http://www.altusmetrum.org/AltOS/.
776 We recommend updating TeleMetrum first, before updating TeleDongle.
779 <title>Updating TeleMetrum Firmware</title>
780 <orderedlist inheritnum='inherit' numeration='arabic'>
782 Find the 'programming cable' that you got as part of the starter
783 kit, that has a red 8-pin MicroMaTch connector on one end and a
784 red 4-pin MicroMaTch connector on the other end.
787 Take the 2 screws out of the TeleDongle case to get access
788 to the circuit board.
791 Plug the 8-pin end of the programming cable to the
792 matching connector on the TeleDongle, and the 4-pin end to the
793 matching connector on the TeleMetrum.
794 Note that each MicroMaTch connector has an alignment pin that
795 goes through a hole in the PC board when you have the cable
799 Attach a battery to the TeleMetrum board.
802 Plug the TeleDongle into your computer's USB port, and power
806 Run AltosUI, and select 'Flash Image' from the File menu.
809 Pick the TeleDongle device from the list, identifying it as the
813 Select the image you want put on the TeleMetrum, which should have a
814 name in the form telemetrum-v1.0-0.7.1.ihx. It should be visible
815 in the default directory, if not you may have to poke around
816 your system to find it.
819 Make sure the configuration parameters are reasonable
820 looking. If the serial number and/or RF configuration
821 values aren't right, you'll need to change them.
824 Hit the 'OK' button and the software should proceed to flash
825 the TeleMetrum with new firmware, showing a progress bar.
828 Confirm that the TeleMetrum board seems to have updated ok, which you
829 can do by plugging in to it over USB and using a terminal program
830 to connect to the board and issue the 'v' command to check
834 If something goes wrong, give it another try.
839 <title>Updating TeleDongle Firmware</title>
841 Updating TeleDongle's firmware is just like updating TeleMetrum
842 firmware, but you switch which board is the programmer and which
843 is the programming target.
845 <orderedlist inheritnum='inherit' numeration='arabic'>
847 Find the 'programming cable' that you got as part of the starter
848 kit, that has a red 8-pin MicroMaTch connector on one end and a
849 red 4-pin MicroMaTch connector on the other end.
852 Find the USB cable that you got as part of the starter kit, and
853 plug the "mini" end in to the mating connector on TeleMetrum.
856 Take the 2 screws out of the TeleDongle case to get access
857 to the circuit board.
860 Plug the 8-pin end of the programming cable to the (latching)
861 matching connector on the TeleMetrum, and the 4-pin end to the
862 matching connector on the TeleDongle.
863 Note that each MicroMaTch connector has an alignment pin that
864 goes through a hole in the PC board when you have the cable
868 Attach a battery to the TeleMetrum board.
871 Plug both TeleMetrum and TeleDongle into your computer's USB
872 ports, and power up the TeleMetrum.
875 Run AltosUI, and select 'Flash Image' from the File menu.
878 Pick the TeleMetrum device from the list, identifying it as the
882 Select the image you want put on the TeleDongle, which should have a
883 name in the form teledongle-v0.2-0.7.1.ihx. It should be visible
884 in the default directory, if not you may have to poke around
885 your system to find it.
888 Make sure the configuration parameters are reasonable
889 looking. If the serial number and/or RF configuration
890 values aren't right, you'll need to change them. The TeleDongle
891 serial number is on the "bottom" of the circuit board, and can
892 usually be read through the translucent blue plastic case without
893 needing to remove the board from the case.
896 Hit the 'OK' button and the software should proceed to flash
897 the TeleDongle with new firmware, showing a progress bar.
900 Confirm that the TeleDongle board seems to have updated ok, which you
901 can do by plugging in to it over USB and using a terminal program
902 to connect to the board and issue the 'v' command to check
903 the version, etc. Once you're happy, remove the programming cable
904 and put the cover back on the TeleDongle.
907 If something goes wrong, give it another try.
911 Be careful removing the programming cable from the locking 8-pin
912 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
913 screwdriver or knife blade to gently pry the locking ears out
914 slightly to extract the connector. We used a locking connector on
915 TeleMetrum to help ensure that the cabling to companion boards
916 used in a rocket don't ever come loose accidentally in flight.
921 <title>Using Altus Metrum Products</title>
923 <title>Being Legal</title>
925 First off, in the US, you need an [amateur radio license](../Radio) or
926 other authorization to legally operate the radio transmitters that are part
930 <title>In the Rocket</title>
932 In the rocket itself, you just need a [TeleMetrum](../TeleMetrum) board and
933 a LiPo rechargeable battery. An 860mAh battery weighs less than a 9V
934 alkaline battery, and will run a [TeleMetrum](../TeleMetrum) for hours.
937 By default, we ship TeleMetrum with a simple wire antenna. If your
938 electronics bay or the airframe it resides within is made of carbon fiber,
939 which is opaque to RF signals, you may choose to have an SMA connector
940 installed so that you can run a coaxial cable to an antenna mounted
941 elsewhere in the rocket.
945 <title>On the Ground</title>
947 To receive the data stream from the rocket, you need an antenna and short
948 feedline connected to one of our [TeleDongle](../TeleDongle) units. The
949 TeleDongle in turn plugs directly into the USB port on a notebook
950 computer. Because TeleDongle looks like a simple serial port, your computer
951 does not require special device drivers... just plug it in.
954 Right now, all of our application software is written for Linux. However,
955 because we understand that many people run Windows or MacOS, we are working
956 on a new ground station program written in Java that should work on all
960 After the flight, you can use the RF link to extract the more detailed data
961 logged in the rocket, or you can use a mini USB cable to plug into the
962 TeleMetrum board directly. Pulling out the data without having to open up
963 the rocket is pretty cool! A USB cable is also how you charge the LiPo
964 battery, so you'll want one of those anyway... the same cable used by lots
965 of digital cameras and other modern electronic stuff will work fine.
968 If your rocket lands out of sight, you may enjoy having a hand-held GPS
969 receiver, so that you can put in a waypoint for the last reported rocket
970 position before touch-down. This makes looking for your rocket a lot like
971 Geo-Cacheing... just go to the waypoint and look around starting from there.
974 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
975 can use that with your antenna to direction-find the rocket on the ground
976 the same way you can use a Walston or Beeline tracker. This can be handy
977 if the rocket is hiding in sage brush or a tree, or if the last GPS position
978 doesn't get you close enough because the rocket dropped into a canyon, or
979 the wind is blowing it across a dry lake bed, or something like that... Keith
980 and Bdale both currently own and use the Yaesu VX-7R at launches.
983 So, to recap, on the ground the hardware you'll need includes:
984 <orderedlist inheritnum='inherit' numeration='arabic'>
986 an antenna and feedline
995 optionally, a handheld GPS receiver
998 optionally, an HT or receiver covering 435 Mhz
1003 The best hand-held commercial directional antennas we've found for radio
1004 direction finding rockets are from
1005 <ulink url="http://www.arrowantennas.com/" >
1008 The 440-3 and 440-5 are both good choices for finding a
1009 TeleMetrum-equipped rocket when used with a suitable 70cm HT.
1013 <title>Data Analysis</title>
1015 Our software makes it easy to log the data from each flight, both the
1016 telemetry received over the RF link during the flight itself, and the more
1017 complete data log recorded in the DataFlash memory on the TeleMetrum
1018 board. Once this data is on your computer, our postflight tools make it
1019 easy to quickly get to the numbers everyone wants, like apogee altitude,
1020 max acceleration, and max velocity. You can also generate and view a
1021 standard set of plots showing the altitude, acceleration, and
1022 velocity of the rocket during flight. And you can even export a data file
1023 useable with Google Maps and Google Earth for visualizing the flight path
1024 in two or three dimensions!
1027 Our ultimate goal is to emit a set of files for each flight that can be
1028 published as a web page per flight, or just viewed on your local disk with
1033 <title>Future Plans</title>
1035 In the future, we intend to offer "companion boards" for the rocket that will
1036 plug in to TeleMetrum to collect additional data, provide more pyro channels,
1037 and so forth. A reference design for a companion board will be documented
1038 soon, and will be compatible with open source Arduino programming tools.
1041 We are also working on the design of a hand-held ground terminal that will
1042 allow monitoring the rocket's status, collecting data during flight, and
1043 logging data after flight without the need for a notebook computer on the
1044 flight line. Particularly since it is so difficult to read most notebook
1045 screens in direct sunlight, we think this will be a great thing to have.
1048 Because all of our work is open, both the hardware designs and the software,
1049 if you have some great idea for an addition to the current Altus Metrum family,
1050 feel free to dive in and help! Or let us know what you'd like to see that
1051 we aren't already working on, and maybe we'll get excited about it too...