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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 be a single, comprehensive manual
76 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 B
92 cable to plug the Telemetrum into your computer's USB socket. The
93 TeleMetrum circuitry will charge the battery whenever it is plugged
94 into the usb socket. The TeleMetrum's on-off switch does NOT control
95 the charging circuitry. When the GPS chip is initially searching for
96 satellites, the unit will pull more current than it can pull from the
97 usb port, so the battery must be plugged in order to get a good
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.
106 The other active device in the starter kit is the half-duplex TeleDongle
107 rf link. If you plug it in to your computer it should "just work",
108 showing up as a serial port device. If you are using Linux and are
109 having problems, try moving to a fresher kernel (2.6.33 or newer), as
110 there were some ugly USB serial driver bugs in earlier versions.
113 Next you should obtain and install the AltOS utilities. The first
114 generation sofware was written for Linux only. New software is coming
115 soon that will also run on Windows and Mac. For now, we'll concentrate
116 on Linux. If you are using Debian, an 'altos' package already exists,
117 see http://altusmetrum.org/AltOS for details on how to install it.
118 User-contributed directions for building packages on ArchLinux may be
119 found in the contrib/arch-linux directory as PKGBUILD files.
120 Between the debian/rules file and the PKGBUILD files in
121 contrib, you should find enough information to learn how to build the
122 software for any other version of Linux.
125 When you have successfully installed the software suite (either from
126 compiled source code or as the pre-built Debian package) you will
127 have 10 or so executable programs all of which have names beginning
129 ('ao-view' is the lone GUI-based program, the rest are command-line
130 oriented.) You will also have man pages, that give you basic info
132 You will also get this documentation in two file types in the doc/
133 directory, telemetrum-doc.pdf and telemetrum-doc.html.
134 Finally you will have a couple control files that allow the ao-view
135 GUI-based program to appear in your menu of programs (under
136 the 'Internet' category).
139 Both Telemetrum and TeleDongle can be directly communicated
140 with using USB ports. The first thing you should try after getting
141 both units plugged into to your computer's usb port(s) is to run
142 'ao-list' from a terminal-window to see what port-device-name each
143 device has been assigned by the operating system.
144 You will need this information to access the devices via their
145 respective on-board firmware and data using other command line
146 programs in the AltOS software suite.
149 To access the device's firmware for configuration you need a terminal
150 program such as you would use to talk to a modem. The software
151 authors prefer using the program 'cu' which comes from the UUCP package
152 on most Unix-like systems such as Linux. An example command line for
153 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
154 indicated from running the
155 ao-list program. Another reasonable terminal program for Linux is
156 'cutecom'. The default 'escape'
157 character used by CU (i.e. the character you use to
158 issue commands to cu itself instead of sending the command as input
159 to the connected device) is a '~'. You will need this for use in
160 only two different ways during normal operations. First is to exit
161 the program by sending a '~.' which is called a 'escape-disconnect'
162 and allows you to close-out from 'cu'. The
163 second use will be outlined later.
166 Both TeleMetrum and TeleDongle share the concept of a two level
167 command set in their firmware.
168 The first layer has several single letter commands. Once
169 you are using 'cu' (or 'cutecom') sending (typing) a '?'
170 returns a full list of these
171 commands. The second level are configuration sub-commands accessed
172 using the 'c' command, for
173 instance typing 'c?' will give you this second level of commands
174 (all of which require the
175 letter 'c' to access). Please note that most configuration options
176 are stored only in DataFlash memory, and only TeleMetrum has this
177 memory to save the various values entered like the channel number
178 and your callsign when powered off. TeleDongle requires that you
179 set these each time you plug it in, which ao-view can help with.
182 Try setting these config ('c' or second level menu) values. A good
183 place to start is by setting your call sign. By default, the boards
184 use 'N0CALL' which is cute, but not exactly legal!
185 Spend a few minutes getting comfortable with the units, their
186 firmware, and 'cu' (or possibly 'cutecom').
187 For instance, try to send
188 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
189 Verify you can connect and disconnect from the units while in your
190 terminal program by sending the escape-disconnect mentioned above.
193 Note that the 'reboot' command, which is very useful on TeleMetrum,
194 will likely just cause problems with the dongle. The *correct* way
195 to reset the dongle is just to unplug and re-plug it.
198 A fun thing to do at the launch site and something you can do while
199 learning how to use these units is to play with the rf-link access
200 of the TeleMetrum from the TeleDongle. Be aware that you *must* create
201 some physical separation between the devices, otherwise the link will
202 not function due to signal overload in the receivers in each device.
205 Now might be a good time to take a break and read the rest of this
206 manual, particularly about the two "modes" that the TeleMetrum
207 can be placed in and how the position of the TeleMetrum when booting
208 up will determine whether the unit is in "pad" or "idle" mode.
211 You can access a TeleMetrum in idle mode from the Teledongle's USB
212 connection using the rf link
213 by issuing a 'p' command to the TeleDongle. Practice connecting and
214 disconnecting ('~~' while using 'cu') from the TeleMetrum. If
215 you cannot escape out of the "p" command, (by using a '~~' when in
216 CU) then it is likely that your kernel has issues. Try a newer version.
219 Using this rf link allows you to configure the TeleMetrum, test
220 fire e-matches and igniters from the flight line, check pyro-match
221 continuity and so forth. You can leave the unit turned on while it
222 is in 'idle mode' and then place the
223 rocket vertically on the launch pad, walk away and then issue a
224 reboot command. The TeleMetrum will reboot and start sending data
225 having changed to the "pad" mode. If the TeleDongle is not receiving
226 this data, you can disconnect 'cu' from the Teledongle using the
227 procedures mentioned above and THEN connect to the TeleDongle from
228 inside 'ao-view'. If this doesn't work, disconnect from the
229 TeleDongle, unplug it, and try again after plugging it back in.
232 Eventually the GPS will find enough satellites, lock in on them,
233 and 'ao-view' will both auditorially announce and visually indicate
235 Now you can launch knowing that you have a good data path and
236 good satellite lock for flight data and recovery. Remember
237 you MUST tell ao-view to connect to the TeleDongle explicitly in
238 order for ao-view to be able to receive data.
241 Both RDF (radio direction finding) tones from the TeleMetrum and
242 GPS trekking data are available and together are very useful in
243 locating the rocket once it has landed. (The last good GPS data
244 received before touch-down will be on the data screen of 'ao-view'.)
247 Once you have recovered the rocket you can download the eeprom
248 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
249 either a USB cable or over the radio link using TeleDongle.
250 And by following the man page for 'ao-postflight' you can create
251 various data output reports, graphs, and even kml data to see the
252 flight trajectory in google-earth. (Moving the viewing angle making
253 sure to connect the yellow lines while in google-earth is the proper
257 As for ao-view.... some things are in the menu but don't do anything
258 very useful. The developers have stopped working on ao-view to focus
259 on a new, cross-platform ground station program. So ao-view may or
260 may not be updated in the future. Mostly you just use
261 the Log and Device menus. It has a wonderful display of the incoming
262 flight data and I am sure you will enjoy what it has to say to you
263 once you enable the voice output!
268 The altimeter (TeleMetrum) seems to shut off when disconnected from the
269 computer. Make sure the battery is adequately charged. Remember the
270 unit will pull more power than the USB port can deliver before the
271 GPS enters "locked" mode. The battery charges best when TeleMetrum
275 It's impossible to stop the TeleDongle when it's in "p" mode, I have
276 to unplug the USB cable? Make sure you have tried to "escape out" of
277 this mode. If this doesn't work the reboot procedure for the
278 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
279 outgoing buffer IF your "escape out" ('~~') does not work.
280 At this point using either 'ao-view' (or possibly
281 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
285 The amber LED (on the TeleMetrum/altimeter) lights up when both
286 battery and USB are connected. Does this mean it's charging?
287 Yes, the yellow LED indicates the charging at the 'regular' rate.
288 If the led is out but the unit is still plugged into a USB port,
289 then the battery is being charged at a 'trickle' rate.
292 There are no "dit-dah-dah-dit" sound like the manual mentions?
293 That's the "pad" mode. Weak batteries might be the problem.
294 It is also possible that the unit is horizontal and the output
295 is instead a "dit-dit" meaning 'idle'.
298 It's unclear how to use 'ao-view' and other programs when 'cu'
299 is running. You cannot have more than one program connected to
300 the TeleDongle at one time without apparent data loss as the
301 incoming data will not make it to both programs intact.
302 Disconnect whatever programs aren't currently being used.
305 How do I save flight data?
306 Live telemetry is written to file(s) whenever 'ao-view' is connected
307 to the TeleDongle. The file area defaults to ~/altos
308 but is easily changed using the menus in 'ao-view'. The files that
309 are written end in '.telem'. The after-flight
310 data-dumped files will end in .eeprom and represent continuous data
311 unlike the rf-linked .telem files that are subject to the
312 turnarounds/data-packaging time slots in the half-duplex rf data path.
313 See the above instructions on what and how to save the eeprom stored
314 data after physically retrieving your TeleMetrum. Make sure to save
315 the on-board data after each flight, as the current firmware will
316 over-write any previous flight data during a new flight.
321 <title>Specifications</title>
325 Recording altimeter for model rocketry.
330 Supports dual deployment (can fire 2 ejection charges).
335 70cm ham-band transceiver for telemetry downlink.
340 Barometric pressure sensor good to 45k feet MSL.
345 1-axis high-g accelerometer for motor characterization, capable of
346 +/- 50g using default part.
351 On-board, integrated GPS receiver with 5hz update rate capability.
356 On-board 1 megabyte non-volatile memory for flight data storage.
361 USB interface for battery charging, configuration, and data recovery.
366 Fully integrated support for LiPo rechargeable batteries.
371 Uses LiPo to fire e-matches, support for optional separate pyro
377 2.75 x 1 inch board designed to fit inside 29mm airframe coupler tube.
383 <title>Handling Precautions</title>
385 TeleMetrum is a sophisticated electronic device. When handled gently and
386 properly installed in an airframe, it will deliver impressive results.
387 However, like all electronic devices, there are some precautions you
391 The Lithium Polymer rechargeable batteries used with TeleMetrum have an
392 extraordinary power density. This is great because we can fly with
393 much less battery mass than if we used alkaline batteries or previous
394 generation rechargeable batteries... but if they are punctured
395 or their leads are allowed to short, they can and will release their
397 Thus we recommend that you take some care when handling our batteries
398 and consider giving them some extra protection in your airframe. We
399 often wrap them in suitable scraps of closed-cell packing foam before
400 strapping them down, for example.
403 The TeleMetrum barometric sensor is sensitive to sunlight. In normal
404 mounting situations, it and all of the other surface mount components
405 are "down" towards whatever the underlying mounting surface is, so
406 this is not normally a problem. Please consider this, though, when
407 designing an installation, for example, in a 29mm airframe with a
408 see-through plastic payload bay.
411 The TeleMetrum barometric sensor sampling port must be able to
413 both by not being covered by foam or tape or other materials that might
414 directly block the hole on the top of the sensor, but also by having a
415 suitable static vent to outside air.
418 As with all other rocketry electronics, TeleMetrum must be protected
419 from exposure to corrosive motor exhaust and ejection charge gasses.
423 <title>Hardware Overview</title>
425 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
426 fit inside coupler for 29mm airframe tubing, but using it in a tube that
427 small in diameter may require some creativity in mounting and wiring
428 to succeed! The default 1/4
429 wave UHF wire antenna attached to the center of the nose-cone end of
430 the board is about 7 inches long, and wiring for a power switch and
431 the e-matches for apogee and main ejection charges depart from the
432 fin can end of the board. Given all this, an ideal "simple" avionics
433 bay for TeleMetrum should have at least 10 inches of interior length.
436 A typical TeleMetrum installation using the on-board GPS antenna and
437 default wire UHF antenna involves attaching only a suitable
438 Lithium Polymer battery, a single pole switch for power on/off, and
439 two pairs of wires connecting e-matches for the apogee and main ejection
443 By default, we use the unregulated output of the LiPo battery directly
444 to fire ejection charges. This works marvelously with standard
445 low-current e-matches like the J-Tek from MJG Technologies, and with
446 Quest Q2G2 igniters. However, if you
447 want or need to use a separate pyro battery, you can do so by adding
448 a second 2mm connector to position B2 on the board and cutting the
449 thick pcb trace connecting the LiPo battery to the pyro circuit between
450 the two silk screen marks on the surface mount side of the board shown
454 We offer two choices of pyro and power switch connector, or you can
455 choose neither and solder wires directly to the board. All three choices
456 are reasonable depending on the constraints of your airframe. Our
457 favorite option when there is sufficient room above the board is to use
458 the Tyco pin header with polarization and locking. If you choose this
459 option, you crimp individual wires for the power switch and e-matches
460 into a mating connector, and installing and removing the TeleMetrum
461 board from an airframe is as easy as plugging or unplugging two
462 connectors. If the airframe will not support this much height or if
463 you want to be able to directly attach e-match leads to the board, we
464 offer a screw terminal block. This is very similar to what most other
465 altimeter vendors provide and so may be the most familiar option.
466 You'll need a very small straight blade screwdriver to connect
467 and disconnect the board in this case, such as you might find in a
468 jeweler's screwdriver set. Finally, you can forego both options and
469 solder wires directly to the board, which may be the best choice for
470 minimum diameter and/or minimum mass designs.
473 For most airframes, the integrated GPS antenna and wire UHF antenna are
474 a great combination. However, if you are installing in a carbon-fiber
475 electronics bay which is opaque to RF signals, you may need to use
476 off-board external antennas instead. In this case, you can order
477 TeleMetrum with an SMA connector for the UHF antenna connection, and
478 you can unplug the integrated GPS antenna and select an appropriate
479 off-board GPS antenna with cable terminating in a U.FL connector.
483 <title>Operation</title>
485 <title>Firmware Modes </title>
487 The AltOS firmware build for TeleMetrum has two fundamental modes,
488 "idle" and "flight". Which of these modes the firmware operates in
489 is determined by the orientation of the rocket (well, actually the
490 board, of course...) at the time power is switched on. If the rocket
491 is "nose up", then TeleMetrum assumes it's on a rail or rod being
492 prepared for launch, so the firmware chooses flight mode. However,
493 if the rocket is more or less horizontal, the firmware instead enters
497 At power on, you will hear three beeps
498 ("S" in Morse code for startup) and then a pause while
499 TeleMetrum completes initialization and self tests, and decides which
503 In flight or "pad" mode, TeleMetrum turns on the GPS system,
505 state machine, goes into transmit-only mode on the RF link sending
506 telemetry, and waits for launch to be detected. Flight mode is
507 indicated by an audible "di-dah-dah-dit" ("P" for pad) on the
509 beeps indicating the state of the pyrotechnic igniter continuity.
510 One beep indicates apogee continuity, two beeps indicate
511 main continuity, three beeps indicate both apogee and main continuity,
512 and one longer "brap" sound indicates no continuity. For a dual
513 deploy flight, make sure you're getting three beeps before launching!
514 For apogee-only or motor eject flights, do what makes sense.
517 In idle mode, you will hear an audible "di-dit" ("I" for idle), and
518 the normal flight state machine is disengaged, thus
519 no ejection charges will fire. TeleMetrum also listens on the RF
520 link when in idle mode for packet mode requests sent from TeleDongle.
521 Commands can be issued to a TeleMetrum in idle mode over either
522 USB or the RF link equivalently.
523 Idle mode is useful for configuring TeleMetrum, for extracting data
524 from the on-board storage chip after flight, and for ground testing
528 One "neat trick" of particular value when TeleMetrum is used with very
529 large airframes, is that you can power the board up while the rocket
530 is horizontal, such that it comes up in idle mode. Then you can
531 raise the airframe to launch position, use a TeleDongle to open
532 a packet connection, and issue a 'reset' command which will cause
533 TeleMetrum to reboot, realize it's now nose-up, and thus choose
534 flight mode. This is much safer than standing on the top step of a
535 rickety step-ladder or hanging off the side of a launch tower with
536 a screw-driver trying to turn on your avionics before installing
543 TeleMetrum includes a complete GPS receiver. See a later section for
544 a brief explanation of how GPS works that will help you understand
545 the information in the telemetry stream. The bottom line is that
546 the TeleMetrum GPS receiver needs to lock onto at least four
547 satellites to obtain a solid 3 dimensional position fix and know
551 TeleMetrum provides backup power to the GPS chip any time a LiPo
552 battery is connected. This allows the receiver to "warm start" on
553 the launch rail much faster than if every power-on were a "cold start"
554 for the GPS receiver. In typical operations, powering up TeleMetrum
555 on the flight line in idle mode while performing final airframe
556 preparation will be sufficient to allow the GPS receiver to cold
557 start and acquire lock. Then the board can be powered down during
558 RSO review and installation on a launch rod or rail. When the board
559 is turned back on, the GPS system should lock very quickly, typically
560 long before igniter installation and return to the flight line are
565 <title>Ground Testing </title>
567 An important aspect of preparing a rocket using electronic deployment
568 for flight is ground testing the recovery system. Thanks
569 to the bi-directional RF link central to the Altus Metrum system,
570 this can be accomplished in a TeleMetrum-equipped rocket without as
571 much work as you may be accustomed to with other systems. It can
575 Just prep the rocket for flight, then power up TeleMetrum while the
576 airframe is horizontal. This will cause the firmware to go into
577 "idle" mode, in which the normal flight state machine is disabled and
578 charges will not fire without manual command. Then, establish an
579 RF packet connection from a TeleDongle-equipped computer using the
580 P command from a safe distance. You can now command TeleMetrum to
581 fire the apogee or main charges to complete your testing.
584 In order to reduce the chance of accidental firing of pyrotechnic
585 charges, the command to fire a charge is intentionally somewhat
586 difficult to type, and the built-in help is slightly cryptic to
587 prevent accidental echoing of characters from the help text back at
588 the board from firing a charge. The command to fire the apogee
589 drogue charge is 'i DoIt drogue' and the command to fire the main
590 charge is 'i DoIt main'.
594 <title>Radio Link </title>
596 The chip our boards are based on incorporates an RF transceiver, but
597 it's not a full duplex system... each end can only be transmitting or
598 receiving at any given moment. So we had to decide how to manage the
602 By design, TeleMetrum firmware listens for an RF connection when
603 it's in "idle mode" (turned on while the rocket is horizontal), which
604 allows us to use the RF link to configure the rocket, do things like
605 ejection tests, and extract data after a flight without having to
606 crack open the airframe. However, when the board is in "flight
607 mode" (turned on when the rocket is vertical) the TeleMetrum only
608 transmits and doesn't listen at all. That's because we want to put
609 ultimate priority on event detection and getting telemetry out of
610 the rocket and out over
611 the RF link in case the rocket crashes and we aren't able to extract
615 We don't use a 'normal packet radio' mode because they're just too
616 inefficient. The GFSK modulation we use is just FSK with the
617 baseband pulses passed through a
618 Gaussian filter before they go into the modulator to limit the
619 transmitted bandwidth. When combined with the hardware forward error
620 correction support in the cc1111 chip, this allows us to have a very
621 robust 38.4 kilobit data link with only 10 milliwatts of transmit power,
622 a whip antenna in the rocket, and a hand-held Yagi on the ground. We've
623 had flights to above 21k feet AGL with good reception, and calculations
624 suggest we should be good to well over 40k feet AGL with a 5-element yagi on
625 the ground. We hope to fly boards to higher altitudes soon, and would
626 of course appreciate customer feedback on performance in higher
631 <title>Configurable Parameters</title>
633 Configuring a TeleMetrum board for flight is very simple. Because we
634 have both acceleration and pressure sensors, there is no need to set
635 a "mach delay", for example. The few configurable parameters can all
636 be set using a simple terminal program over the USB port or RF link
640 <title>Radio Channel</title>
642 Our firmware supports 10 channels. The default channel 0 corresponds
643 to a center frequency of 434.550 Mhz, and channels are spaced every
644 100 khz. Thus, channel 1 is 434.650 Mhz, and channel 9 is 435.550 Mhz.
645 At any given launch, we highly recommend coordinating who will use
646 each channel and when to avoid interference. And of course, both
647 TeleMetrum and TeleDongle must be configured to the same channel to
648 successfully communicate with each other.
651 To set the radio channel, use the 'c r' command, like 'c r 3' to set
653 As with all 'c' sub-commands, follow this with a 'c w' to write the
654 change to the parameter block in the on-board DataFlash chip on
655 your TeleMetrum board if you want the change to stay in place across reboots.
659 <title>Apogee Delay</title>
661 Apogee delay is the number of seconds after TeleMetrum detects flight
662 apogee that the drogue charge should be fired. In most cases, this
663 should be left at the default of 0. However, if you are flying
664 redundant electronics such as for an L3 certification, you may wish
665 to set one of your altimeters to a positive delay so that both
666 primary and backup pyrotechnic charges do not fire simultaneously.
669 To set the apogee delay, use the [FIXME] command.
670 As with all 'c' sub-commands, follow this with a 'c w' to write the
671 change to the parameter block in the on-board DataFlash chip.
674 Please note that the TeleMetrum apogee detection algorithm always
675 fires a fraction of a second *after* apogee. If you are also flying
676 an altimeter like the PerfectFlite MAWD, which only supports selecting
677 0 or 1 seconds of apogee delay, you may wish to set the MAWD to 0
678 seconds delay and set the TeleMetrum to fire your backup 2 or 3
679 seconds later to avoid any chance of both charges firing
680 simultaneously. We've flown several airframes this way quite happily,
681 including Keith's successful L3 cert.
685 <title>Main Deployment Altitude</title>
687 By default, TeleMetrum will fire the main deployment charge at an
688 elevation of 250 meters (about 820 feet) above ground. We think this
689 is a good elevation for most airframes, but feel free to change this
690 to suit. In particular, if you are flying two altimeters, you may
692 deployment elevation for the backup altimeter to be something lower
693 than the primary so that both pyrotechnic charges don't fire
697 To set the main deployment altitude, use the [FIXME] command.
698 As with all 'c' sub-commands, follow this with a 'c w' to write the
699 change to the parameter block in the on-board DataFlash chip.
704 <title>Calibration</title>
706 There are only two calibrations required for a TeleMetrum board, and
707 only one for TeleDongle.
710 <title>Radio Frequency</title>
712 The radio frequency is synthesized from a clock based on the 48 Mhz
713 crystal on the board. The actual frequency of this oscillator must be
714 measured to generate a calibration constant. While our GFSK modulation
715 bandwidth is wide enough to allow boards to communicate even when
716 their oscillators are not on exactly the same frequency, performance
717 is best when they are closely matched.
718 Radio frequency calibration requires a calibrated frequency counter.
719 Fortunately, once set, the variation in frequency due to aging and
720 temperature changes is small enough that re-calibration by customers
721 should generally not be required.
724 To calibrate the radio frequency, connect the UHF antenna port to a
725 frequency counter, set the board to channel 0, and use the 'C'
726 command to generate a CW carrier. Wait for the transmitter temperature
727 to stabilize and the frequency to settle down.
728 Then, divide 434.550 Mhz by the
729 measured frequency and multiply by the current radio cal value show
730 in the 'c s' command. For an unprogrammed board, the default value
731 is 1186611. Take the resulting integer and program it using the 'c f'
732 command. Testing with the 'C' command again should show a carrier
733 within a few tens of Hertz of the intended frequency.
734 As with all 'c' sub-commands, follow this with a 'c w' to write the
735 change to the parameter block in the on-board DataFlash chip.
739 <title>Accelerometer</title>
741 The accelerometer we use has its own 5 volt power supply and
742 the output must be passed through a resistive voltage divider to match
743 the input of our 3.3 volt ADC. This means that unlike the barometric
744 sensor, the output of the acceleration sensor is not ratiometric to
745 the ADC converter, and calibration is required. We also support the
746 use of any of several accelerometers from a Freescale family that
747 includes at least +/- 40g, 50g, 100g, and 200g parts. Using gravity,
748 a simple 2-point calibration yields acceptable results capturing both
749 the different sensitivities and ranges of the different accelerometer
750 parts and any variation in power supply voltages or resistor values
751 in the divider network.
754 To calibrate the acceleration sensor, use the 'c a 0' command. You
755 will be prompted to orient the board vertically with the UHF antenna
756 up and press a key, then to orient the board vertically with the
757 UHF antenna down and press a key.
758 As with all 'c' sub-commands, follow this with a 'c w' to write the
759 change to the parameter block in the on-board DataFlash chip.
762 The +1g and -1g calibration points are included in each telemetry
763 frame and are part of the header extracted by ao-dumplog after flight.
764 Note that we always store and return raw ADC samples for each
765 sensor... nothing is permanently "lost" or "damaged" if the
772 <title>Updating Device Firmware</title>
774 The big conceptual thing to realize is that you have to use a
775 TeleDongle as a programmer to update a TeleMetrum, and vice versa.
776 Due to limited memory resources in the cc1111, we don't support
777 programming either unit directly over USB.
780 You may wish to begin by ensuring you have current firmware images.
781 These are distributed as part of the AltOS software bundle that
782 also includes the AltosUI ground station program. Newer ground
783 station versions typically work fine with older firmware versions,
784 so you don't need to update your devices just to try out new
785 software features. You can always download the most recent
786 version from http://www.altusmetrum.org/AltOS/.
789 We recommend updating TeleMetrum first, before updating TeleDongle.
792 <title>Updating TeleMetrum Firmware</title>
793 <orderedlist inheritnum='inherit' numeration='arabic'>
795 Find the 'programming cable' that you got as part of the starter
796 kit, that has a red 8-pin MicroMaTch connector on one end and a
797 red 4-pin MicroMaTch connector on the other end.
801 Take the 2 screws out of the TeleDongle case to get access
802 to the circuit board.
805 Plug the 8-pin end of the programming cable to the
806 matching connector on the TeleDongle, and the 4-pin end to the
807 matching connector on the TeleMetrum.
810 Attach a battery to the TeleMetrum board.
813 Plug the TeleDongle into your computer's USB port, and power
817 Run AltosUI, and select 'Flash Image' from the File menu.
820 Pick the TeleDongle device from the list, identifying it as the
824 Select the image you want put on the TeleMetrum, which should have a
825 name in the form telemetrum-v1.0-0.7.1.ihx. It should be visible
826 in the default directory, if not you may have to poke around
827 your system to find it.
830 Make sure the configuration parameters are reasonable
831 looking. If the serial number and/or RF configuration
832 values aren't right, you'll need to change them.
835 Hit the 'OK' button and the software should proceed to flash
836 the TeleMetrum with new firmware, showing a progress bar.
839 Confirm that the TeleMetrum board seems to have updated ok, which you
840 can do by plugging in to it over USB and using a terminal program
841 to connect to the board and issue the 'v' command to check
845 If something goes wrong, give it another try.
850 <title>Updating TeleDongle Firmware</title>
852 Updating TeleDongle's firmware is just like updating TeleMetrum
853 firmware, but you switch which board is the programmer and which
854 is the programming target.
856 <orderedlist inheritnum='inherit' numeration='arabic'>
858 Find the 'programming cable' that you got as part of the starter
859 kit, that has a red 8-pin MicroMaTch connector on one end and a
860 red 4-pin MicroMaTch connector on the other end.
863 Find the USB cable that you got as part of the starter kit, and
864 plug the "mini" end in to the mating connector on TeleMetrum.
867 Take the 2 screws out of the TeleDongle case to get access
868 to the circuit board.
871 Plug the 8-pin end of the programming cable to the (latching)
872 matching connector on the TeleMetrum, and the 4-pin end to the
873 matching connector on the TeleDongle.
876 Attach a battery to the TeleMetrum board.
879 Plug both TeleMetrum and TeleDongle into your computer's USB
880 ports, and power up the TeleMetrum.
883 Run AltosUI, and select 'Flash Image' from the File menu.
886 Pick the TeleMongle device from the list, identifying it as the
890 Select the image you want put on the TeleDongle, which should have a
891 name in the form teledongle-v0.2-0.7.1.ihx. It should be visible
892 in the default directory, if not you may have to poke around
893 your system to find it.
896 Make sure the configuration parameters are reasonable
897 looking. If the serial number and/or RF configuration
898 values aren't right, you'll need to change them. The TeleDongle
899 serial number is on the "bottom" of the circuit board, and can
900 usually be read through the translucent blue plastic case without
901 needing to remove the board from the case.
904 Hit the 'OK' button and the software should proceed to flash
905 the TeleDongle with new firmware, showing a progress bar.
908 Confirm that the TeleDongle board seems to have updated ok, which you
909 can do by plugging in to it over USB and using a terminal program
910 to connect to the board and issue the 'v' command to check
911 the version, etc. Once you're happy, remove the programming cable
912 and put the cover back on the TeleDongle.
915 If something goes wrong, give it another try.
919 Be careful removing the programming cable from the locking 8-pin
920 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
921 screwdriver or knife blade to gently pry the locking ears out
922 slightly to extract the connector. We used a locking connector on
923 TeleMetrum to help ensure that the cabling to companion boards
924 used in a rocket don't ever come loose accidentally in flight.
929 <title>Using Altus Metrum Products</title>
931 <title>Being Legal</title>
933 First off, in the US, you need an [amateur radio license](../Radio) or
934 other authorization to legally operate the radio transmitters that are part
938 <title>In the Rocket</title>
940 In the rocket itself, you just need a [TeleMetrum](../TeleMetrum) board and
941 a LiPo rechargeable battery. An 860mAh battery weighs less than a 9V
942 alkaline battery, and will run a [TeleMetrum](../TeleMetrum) for hours.
945 By default, we ship TeleMetrum with a simple wire antenna. If your
946 electronics bay or the airframe it resides within is made of carbon fiber,
947 which is opaque to RF signals, you may choose to have an SMA connector
948 installed so that you can run a coaxial cable to an antenna mounted
949 elsewhere in the rocket.
953 <title>On the Ground</title>
955 To receive the data stream from the rocket, you need an antenna and short
956 feedline connected to one of our [TeleDongle](../TeleDongle) units. The
957 TeleDongle in turn plugs directly into the USB port on a notebook
958 computer. Because TeleDongle looks like a simple serial port, your computer
959 does not require special device drivers... just plug it in.
962 Right now, all of our application software is written for Linux. However,
963 because we understand that many people run Windows or MacOS, we are working
964 on a new ground station program written in Java that should work on all
968 After the flight, you can use the RF link to extract the more detailed data
969 logged in the rocket, or you can use a mini USB cable to plug into the
970 TeleMetrum board directly. Pulling out the data without having to open up
971 the rocket is pretty cool! A USB cable is also how you charge the LiPo
972 battery, so you'll want one of those anyway... the same cable used by lots
973 of digital cameras and other modern electronic stuff will work fine.
976 If your rocket lands out of sight, you may enjoy having a hand-held GPS
977 receiver, so that you can put in a waypoint for the last reported rocket
978 position before touch-down. This makes looking for your rocket a lot like
979 Geo-Cacheing... just go to the waypoint and look around starting from there.
982 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
983 can use that with your antenna to direction-find the rocket on the ground
984 the same way you can use a Walston or Beeline tracker. This can be handy
985 if the rocket is hiding in sage brush or a tree, or if the last GPS position
986 doesn't get you close enough because the rocket dropped into a canyon, or
987 the wind is blowing it across a dry lake bed, or something like that... Keith
988 and Bdale both currently own and use the Yaesu VX-7R at launches.
991 So, to recap, on the ground the hardware you'll need includes:
992 <orderedlist inheritnum='inherit' numeration='arabic'>
994 an antenna and feedline
1003 optionally, a handheld GPS receiver
1006 optionally, an HT or receiver covering 435 Mhz
1011 The best hand-held commercial directional antennas we've found for radio
1012 direction finding rockets are from
1013 <ulink url="http://www.arrowantennas.com/" >
1016 The 440-3 and 440-5 are both good choices for finding a
1017 TeleMetrum-equipped rocket when used with a suitable 70cm HT.
1021 <title>Data Analysis</title>
1023 Our software makes it easy to log the data from each flight, both the
1024 telemetry received over the RF link during the flight itself, and the more
1025 complete data log recorded in the DataFlash memory on the TeleMetrum
1026 board. Once this data is on your computer, our postflight tools make it
1027 easy to quickly get to the numbers everyone wants, like apogee altitude,
1028 max acceleration, and max velocity. You can also generate and view a
1029 standard set of plots showing the altitude, acceleration, and
1030 velocity of the rocket during flight. And you can even export a data file
1031 useable with Google Maps and Google Earth for visualizing the flight path
1032 in two or three dimensions!
1035 Our ultimate goal is to emit a set of files for each flight that can be
1036 published as a web page per flight, or just viewed on your local disk with
1041 <title>Future Plans</title>
1043 In the future, we intend to offer "companion boards" for the rocket that will
1044 plug in to TeleMetrum to collect additional data, provide more pyro channels,
1045 and so forth. A reference design for a companion board will be documented
1046 soon, and will be compatible with open source Arduino programming tools.
1049 We are also working on the design of a hand-held ground terminal that will
1050 allow monitoring the rocket's status, collecting data during flight, and
1051 logging data after flight without the need for a notebook computer on the
1052 flight line. Particularly since it is so difficult to read most notebook
1053 screens in direct sunlight, we think this will be a great thing to have.
1056 Because all of our work is open, both the hardware designs and the software,
1057 if you have some great idea for an addition to the current Altus Metrum family,
1058 feel free to dive in and help! Or let us know what you'd like to see that
1059 we aren't already working on, and maybe we'll get excited about it too...