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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>0.8</revnumber>
32 <date>24 November 2010</date>
33 <revremark>Updated for software version 0.8 </revremark>
38 <title>Introduction and Overview</title>
40 Welcome to the Altus Metrum community! Our circuits and software reflect
41 our passion for both hobby rocketry and Free Software. We hope their
42 capabilities and performance will delight you in every way, but by
43 releasing all of our hardware and software designs under open licenses,
44 we also hope to empower you to take as active a role in our collective
48 The focal point of our community is TeleMetrum, a dual deploy altimeter
49 with fully integrated GPS and radio telemetry as standard features, and
50 a "companion interface" that will support optional capabilities in the
54 Complementing TeleMetrum is TeleDongle, a USB to RF interface for
55 communicating with TeleMetrum. Combined with your choice of antenna and
56 notebook computer, TeleDongle and our associated user interface software
57 form a complete ground station capable of logging and displaying in-flight
58 telemetry, aiding rocket recovery, then processing and archiving flight
59 data for analysis and review.
62 More products will be added to the Altus Metrum family over time, and
63 we currently envision that this will be a single, comprehensive manual
64 for the entire product family.
68 <title>Getting Started</title>
70 This chapter began as "The Mere-Mortals Quick Start/Usage Guide to
71 the Altus Metrum Starter Kit" by Bob Finch, W9YA, NAR 12965, TRA 12350,
72 w9ya@amsat.org. Bob was one of our first customers for a production
73 TeleMetrum, and the enthusiasm that led to his contribution of this
74 section is immensely gratifying and highy appreciated!
77 The first thing to do after you check the inventory of parts in your
78 "starter kit" is to charge the battery by plugging it into the
79 corresponding socket of the TeleMetrum and then using the USB A to
81 cable to plug the Telemetrum into your computer's USB socket. The
82 TeleMetrum circuitry will charge the battery whenever it is plugged
83 in, because the TeleMetrum's on-off switch does NOT control the
84 charging circuitry. When the GPS chip is initially searching for
85 satellites, TeleMetrum will consume more current than it can pull
86 from the usb port, so the battery must be attached in order to get
87 satellite lock. Once GPS is locked, the current consumption goes back
88 down enough to enable charging while
89 running. So it's a good idea to fully charge the battery as your
90 first item of business so there is no issue getting and maintaining
91 satellite lock. The yellow charge indicator led will go out when the
92 battery is nearly full and the charger goes to trickle charge. It
93 can takeseveral hours to fully recharge a deeply discharged battery.
96 The other active device in the starter kit is the TeleDongle USB to
97 RF interface. If you plug it in to your Mac or Linux computer it should
98 "just work", showing up as a serial port device. Windows systems need
99 driver information that is part of the AltOS download to know that the
100 existing USB modem driver will work. If you are using Linux and are
101 having problems, try moving to a fresher kernel (2.6.33 or newer), as
102 the USB serial driver had ugly bugs in some earlier versions.
105 Next you should obtain and install the AltOS utilities. These include
106 the AltosUI ground station program, current firmware images for
107 TeleMetrum and TeleDongle, and a number of standalone utilities that
108 are rarely needed. Pre-built binary packages are available for Debian
109 Linux, Microsoft Windows, and recent MacOSX versions. Full sourcecode
110 and build instructions for some other Linux variants are also available.
111 The latest version may always be downloaded from
112 http://altusmetrum.org/AltOS.
115 Both Telemetrum and TeleDongle can be directly communicated
116 with using USB ports. The first thing you should try after getting
117 both units plugged into to your computer's usb port(s) is to run
118 'ao-list' from a terminal-window to see what port-device-name each
119 device has been assigned by the operating system.
120 You will need this information to access the devices via their
121 respective on-board firmware and data using other command line
122 programs in the AltOS software suite.
125 To access the device's firmware for configuration you need a terminal
126 program such as you would use to talk to a modem. The software
127 authors prefer using the program 'cu' which comes from the UUCP package
128 on most Unix-like systems such as Linux. An example command line for
129 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
130 indicated from running the
131 ao-list program. Another reasonable terminal program for Linux is
132 'cutecom'. The default 'escape'
133 character used by CU (i.e. the character you use to
134 issue commands to cu itself instead of sending the command as input
135 to the connected device) is a '~'. You will need this for use in
136 only two different ways during normal operations. First is to exit
137 the program by sending a '~.' which is called a 'escape-disconnect'
138 and allows you to close-out from 'cu'. The
139 second use will be outlined later.
142 Both TeleMetrum and TeleDongle share the concept of a two level
143 command set in their firmware.
144 The first layer has several single letter commands. Once
145 you are using 'cu' (or 'cutecom') sending (typing) a '?'
146 returns a full list of these
147 commands. The second level are configuration sub-commands accessed
148 using the 'c' command, for
149 instance typing 'c?' will give you this second level of commands
150 (all of which require the
151 letter 'c' to access). Please note that most configuration options
152 are stored only in DataFlash memory, and only TeleMetrum has this
153 memory to save the various values entered like the channel number
154 and your callsign when powered off. TeleDongle requires that you
155 set these each time you plug it in, which ao-view can help with.
158 Try setting these config ('c' or second level menu) values. A good
159 place to start is by setting your call sign. By default, the boards
160 use 'N0CALL' which is cute, but not exactly legal!
161 Spend a few minutes getting comfortable with the units, their
162 firmware, and 'cu' (or possibly 'cutecom').
163 For instance, try to send
164 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
165 Verify you can connect and disconnect from the units while in your
166 terminal program by sending the escape-disconnect mentioned above.
169 Note that the 'reboot' command, which is very useful on TeleMetrum,
170 will likely just cause problems with the dongle. The *correct* way
171 to reset the dongle is just to unplug and re-plug it.
174 A fun thing to do at the launch site and something you can do while
175 learning how to use these units is to play with the rf-link access
176 of the TeleMetrum from the TeleDongle. Be aware that you *must* create
177 some physical separation between the devices, otherwise the link will
178 not function due to signal overload in the receivers in each device.
181 Now might be a good time to take a break and read the rest of this
182 manual, particularly about the two "modes" that the TeleMetrum
183 can be placed in and how the position of the TeleMetrum when booting
184 up will determine whether the unit is in "pad" or "idle" mode.
187 You can access a TeleMetrum in idle mode from the Teledongle's USB
188 connection using the rf link
189 by issuing a 'p' command to the TeleDongle. Practice connecting and
190 disconnecting ('~~' while using 'cu') from the TeleMetrum. If
191 you cannot escape out of the "p" command, (by using a '~~' when in
192 CU) then it is likely that your kernel has issues. Try a newer version.
195 Using this rf link allows you to configure the TeleMetrum, test
196 fire e-matches and igniters from the flight line, check pyro-match
197 continuity and so forth. You can leave the unit turned on while it
198 is in 'idle mode' and then place the
199 rocket vertically on the launch pad, walk away and then issue a
200 reboot command. The TeleMetrum will reboot and start sending data
201 having changed to the "pad" mode. If the TeleDongle is not receiving
202 this data, you can disconnect 'cu' from the Teledongle using the
203 procedures mentioned above and THEN connect to the TeleDongle from
204 inside 'ao-view'. If this doesn't work, disconnect from the
205 TeleDongle, unplug it, and try again after plugging it back in.
208 Eventually the GPS will find enough satellites, lock in on them,
209 and 'ao-view' will both auditorially announce and visually indicate
211 Now you can launch knowing that you have a good data path and
212 good satellite lock for flight data and recovery. Remember
213 you MUST tell ao-view to connect to the TeleDongle explicitly in
214 order for ao-view to be able to receive data.
217 Both RDF (radio direction finding) tones from the TeleMetrum and
218 GPS trekking data are available and together are very useful in
219 locating the rocket once it has landed. (The last good GPS data
220 received before touch-down will be on the data screen of 'ao-view'.)
223 Once you have recovered the rocket you can download the eeprom
224 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
225 either a USB cable or over the radio link using TeleDongle.
226 And by following the man page for 'ao-postflight' you can create
227 various data output reports, graphs, and even kml data to see the
228 flight trajectory in google-earth. (Moving the viewing angle making
229 sure to connect the yellow lines while in google-earth is the proper
233 As for ao-view.... some things are in the menu but don't do anything
234 very useful. The developers have stopped working on ao-view to focus
235 on a new, cross-platform ground station program. So ao-view may or
236 may not be updated in the future. Mostly you just use
237 the Log and Device menus. It has a wonderful display of the incoming
238 flight data and I am sure you will enjoy what it has to say to you
239 once you enable the voice output!
244 The altimeter (TeleMetrum) seems to shut off when disconnected from the
245 computer. Make sure the battery is adequately charged. Remember the
246 unit will pull more power than the USB port can deliver before the
247 GPS enters "locked" mode. The battery charges best when TeleMetrum
251 It's impossible to stop the TeleDongle when it's in "p" mode, I have
252 to unplug the USB cable? Make sure you have tried to "escape out" of
253 this mode. If this doesn't work the reboot procedure for the
254 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
255 outgoing buffer IF your "escape out" ('~~') does not work.
256 At this point using either 'ao-view' (or possibly
257 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
261 The amber LED (on the TeleMetrum/altimeter) lights up when both
262 battery and USB are connected. Does this mean it's charging?
263 Yes, the yellow LED indicates the charging at the 'regular' rate.
264 If the led is out but the unit is still plugged into a USB port,
265 then the battery is being charged at a 'trickle' rate.
268 There are no "dit-dah-dah-dit" sound like the manual mentions?
269 That's the "pad" mode. Weak batteries might be the problem.
270 It is also possible that the unit is horizontal and the output
271 is instead a "dit-dit" meaning 'idle'.
274 It's unclear how to use 'ao-view' and other programs when 'cu'
275 is running. You cannot have more than one program connected to
276 the TeleDongle at one time without apparent data loss as the
277 incoming data will not make it to both programs intact.
278 Disconnect whatever programs aren't currently being used.
281 How do I save flight data?
282 Live telemetry is written to file(s) whenever 'ao-view' is connected
283 to the TeleDongle. The file area defaults to ~/altos
284 but is easily changed using the menus in 'ao-view'. The files that
285 are written end in '.telem'. The after-flight
286 data-dumped files will end in .eeprom and represent continuous data
287 unlike the rf-linked .telem files that are subject to the
288 turnarounds/data-packaging time slots in the half-duplex rf data path.
289 See the above instructions on what and how to save the eeprom stored
290 data after physically retrieving your TeleMetrum. Make sure to save
291 the on-board data after each flight, as the current firmware will
292 over-write any previous flight data during a new flight.
297 <title>Specifications</title>
301 Recording altimeter for model rocketry.
306 Supports dual deployment (can fire 2 ejection charges).
311 70cm ham-band transceiver for telemetry downlink.
316 Barometric pressure sensor good to 45k feet MSL.
321 1-axis high-g accelerometer for motor characterization, capable of
322 +/- 50g using default part.
327 On-board, integrated GPS receiver with 5hz update rate capability.
332 On-board 1 megabyte non-volatile memory for flight data storage.
337 USB interface for battery charging, configuration, and data recovery.
342 Fully integrated support for LiPo rechargeable batteries.
347 Uses LiPo to fire e-matches, support for optional separate pyro
353 2.75 x 1 inch board designed to fit inside 29mm airframe coupler tube.
359 <title>Handling Precautions</title>
361 TeleMetrum is a sophisticated electronic device. When handled gently and
362 properly installed in an airframe, it will deliver impressive results.
363 However, like all electronic devices, there are some precautions you
367 The Lithium Polymer rechargeable batteries used with TeleMetrum have an
368 extraordinary power density. This is great because we can fly with
369 much less battery mass than if we used alkaline batteries or previous
370 generation rechargeable batteries... but if they are punctured
371 or their leads are allowed to short, they can and will release their
373 Thus we recommend that you take some care when handling our batteries
374 and consider giving them some extra protection in your airframe. We
375 often wrap them in suitable scraps of closed-cell packing foam before
376 strapping them down, for example.
379 The TeleMetrum barometric sensor is sensitive to sunlight. In normal
380 mounting situations, it and all of the other surface mount components
381 are "down" towards whatever the underlying mounting surface is, so
382 this is not normally a problem. Please consider this, though, when
383 designing an installation, for example, in a 29mm airframe with a
384 see-through plastic payload bay.
387 The TeleMetrum barometric sensor sampling port must be able to
389 both by not being covered by foam or tape or other materials that might
390 directly block the hole on the top of the sensor, but also by having a
391 suitable static vent to outside air.
394 As with all other rocketry electronics, TeleMetrum must be protected
395 from exposure to corrosive motor exhaust and ejection charge gasses.
399 <title>Hardware Overview</title>
401 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
402 fit inside coupler for 29mm airframe tubing, but using it in a tube that
403 small in diameter may require some creativity in mounting and wiring
404 to succeed! The default 1/4
405 wave UHF wire antenna attached to the center of the nose-cone end of
406 the board is about 7 inches long, and wiring for a power switch and
407 the e-matches for apogee and main ejection charges depart from the
408 fin can end of the board. Given all this, an ideal "simple" avionics
409 bay for TeleMetrum should have at least 10 inches of interior length.
412 A typical TeleMetrum installation using the on-board GPS antenna and
413 default wire UHF antenna involves attaching only a suitable
414 Lithium Polymer battery, a single pole switch for power on/off, and
415 two pairs of wires connecting e-matches for the apogee and main ejection
419 By default, we use the unregulated output of the LiPo battery directly
420 to fire ejection charges. This works marvelously with standard
421 low-current e-matches like the J-Tek from MJG Technologies, and with
422 Quest Q2G2 igniters. However, if you
423 want or need to use a separate pyro battery, you can do so by adding
424 a second 2mm connector to position B2 on the board and cutting the
425 thick pcb trace connecting the LiPo battery to the pyro circuit between
426 the two silk screen marks on the surface mount side of the board shown
430 We offer two choices of pyro and power switch connector, or you can
431 choose neither and solder wires directly to the board. All three choices
432 are reasonable depending on the constraints of your airframe. Our
433 favorite option when there is sufficient room above the board is to use
434 the Tyco pin header with polarization and locking. If you choose this
435 option, you crimp individual wires for the power switch and e-matches
436 into a mating connector, and installing and removing the TeleMetrum
437 board from an airframe is as easy as plugging or unplugging two
438 connectors. If the airframe will not support this much height or if
439 you want to be able to directly attach e-match leads to the board, we
440 offer a screw terminal block. This is very similar to what most other
441 altimeter vendors provide and so may be the most familiar option.
442 You'll need a very small straight blade screwdriver to connect
443 and disconnect the board in this case, such as you might find in a
444 jeweler's screwdriver set. Finally, you can forego both options and
445 solder wires directly to the board, which may be the best choice for
446 minimum diameter and/or minimum mass designs.
449 For most airframes, the integrated GPS antenna and wire UHF antenna are
450 a great combination. However, if you are installing in a carbon-fiber
451 electronics bay which is opaque to RF signals, you may need to use
452 off-board external antennas instead. In this case, you can order
453 TeleMetrum with an SMA connector for the UHF antenna connection, and
454 you can unplug the integrated GPS antenna and select an appropriate
455 off-board GPS antenna with cable terminating in a U.FL connector.
459 <title>System Operation</title>
461 <title>Firmware Modes </title>
463 The AltOS firmware build for TeleMetrum has two fundamental modes,
464 "idle" and "flight". Which of these modes the firmware operates in
465 is determined by the orientation of the rocket (well, actually the
466 board, of course...) at the time power is switched on. If the rocket
467 is "nose up", then TeleMetrum assumes it's on a rail or rod being
468 prepared for launch, so the firmware chooses flight mode. However,
469 if the rocket is more or less horizontal, the firmware instead enters
473 At power on, you will hear three beeps
474 ("S" in Morse code for startup) and then a pause while
475 TeleMetrum completes initialization and self tests, and decides which
479 In flight or "pad" mode, TeleMetrum turns on the GPS system,
481 state machine, goes into transmit-only mode on the RF link sending
482 telemetry, and waits for launch to be detected. Flight mode is
483 indicated by an audible "di-dah-dah-dit" ("P" for pad) on the
485 beeps indicating the state of the pyrotechnic igniter continuity.
486 One beep indicates apogee continuity, two beeps indicate
487 main continuity, three beeps indicate both apogee and main continuity,
488 and one longer "brap" sound indicates no continuity. For a dual
489 deploy flight, make sure you're getting three beeps before launching!
490 For apogee-only or motor eject flights, do what makes sense.
493 In idle mode, you will hear an audible "di-dit" ("I" for idle), and
494 the normal flight state machine is disengaged, thus
495 no ejection charges will fire. TeleMetrum also listens on the RF
496 link when in idle mode for packet mode requests sent from TeleDongle.
497 Commands can be issued to a TeleMetrum in idle mode over either
498 USB or the RF link equivalently.
499 Idle mode is useful for configuring TeleMetrum, for extracting data
500 from the on-board storage chip after flight, and for ground testing
504 One "neat trick" of particular value when TeleMetrum is used with very
505 large airframes, is that you can power the board up while the rocket
506 is horizontal, such that it comes up in idle mode. Then you can
507 raise the airframe to launch position, use a TeleDongle to open
508 a packet connection, and issue a 'reset' command which will cause
509 TeleMetrum to reboot, realize it's now nose-up, and thus choose
510 flight mode. This is much safer than standing on the top step of a
511 rickety step-ladder or hanging off the side of a launch tower with
512 a screw-driver trying to turn on your avionics before installing
519 TeleMetrum includes a complete GPS receiver. See a later section for
520 a brief explanation of how GPS works that will help you understand
521 the information in the telemetry stream. The bottom line is that
522 the TeleMetrum GPS receiver needs to lock onto at least four
523 satellites to obtain a solid 3 dimensional position fix and know
527 TeleMetrum provides backup power to the GPS chip any time a LiPo
528 battery is connected. This allows the receiver to "warm start" on
529 the launch rail much faster than if every power-on were a "cold start"
530 for the GPS receiver. In typical operations, powering up TeleMetrum
531 on the flight line in idle mode while performing final airframe
532 preparation will be sufficient to allow the GPS receiver to cold
533 start and acquire lock. Then the board can be powered down during
534 RSO review and installation on a launch rod or rail. When the board
535 is turned back on, the GPS system should lock very quickly, typically
536 long before igniter installation and return to the flight line are
541 <title>Ground Testing </title>
543 An important aspect of preparing a rocket using electronic deployment
544 for flight is ground testing the recovery system. Thanks
545 to the bi-directional RF link central to the Altus Metrum system,
546 this can be accomplished in a TeleMetrum-equipped rocket without as
547 much work as you may be accustomed to with other systems. It can
551 Just prep the rocket for flight, then power up TeleMetrum while the
552 airframe is horizontal. This will cause the firmware to go into
553 "idle" mode, in which the normal flight state machine is disabled and
554 charges will not fire without manual command. Then, establish an
555 RF packet connection from a TeleDongle-equipped computer using the
556 P command from a safe distance. You can now command TeleMetrum to
557 fire the apogee or main charges to complete your testing.
560 In order to reduce the chance of accidental firing of pyrotechnic
561 charges, the command to fire a charge is intentionally somewhat
562 difficult to type, and the built-in help is slightly cryptic to
563 prevent accidental echoing of characters from the help text back at
564 the board from firing a charge. The command to fire the apogee
565 drogue charge is 'i DoIt drogue' and the command to fire the main
566 charge is 'i DoIt main'.
570 <title>Radio Link </title>
572 The chip our boards are based on incorporates an RF transceiver, but
573 it's not a full duplex system... each end can only be transmitting or
574 receiving at any given moment. So we had to decide how to manage the
578 By design, TeleMetrum firmware listens for an RF connection when
579 it's in "idle mode" (turned on while the rocket is horizontal), which
580 allows us to use the RF link to configure the rocket, do things like
581 ejection tests, and extract data after a flight without having to
582 crack open the airframe. However, when the board is in "flight
583 mode" (turned on when the rocket is vertical) the TeleMetrum only
584 transmits and doesn't listen at all. That's because we want to put
585 ultimate priority on event detection and getting telemetry out of
586 the rocket and out over
587 the RF link in case the rocket crashes and we aren't able to extract
591 We don't use a 'normal packet radio' mode because they're just too
592 inefficient. The GFSK modulation we use is just FSK with the
593 baseband pulses passed through a
594 Gaussian filter before they go into the modulator to limit the
595 transmitted bandwidth. When combined with the hardware forward error
596 correction support in the cc1111 chip, this allows us to have a very
597 robust 38.4 kilobit data link with only 10 milliwatts of transmit power,
598 a whip antenna in the rocket, and a hand-held Yagi on the ground. We've
599 had flights to above 21k feet AGL with good reception, and calculations
600 suggest we should be good to well over 40k feet AGL with a 5-element yagi on
601 the ground. We hope to fly boards to higher altitudes soon, and would
602 of course appreciate customer feedback on performance in higher
607 <title>Configurable Parameters</title>
609 Configuring a TeleMetrum board for flight is very simple. Because we
610 have both acceleration and pressure sensors, there is no need to set
611 a "mach delay", for example. The few configurable parameters can all
612 be set using a simple terminal program over the USB port or RF link
616 <title>Radio Channel</title>
618 Our firmware supports 10 channels. The default channel 0 corresponds
619 to a center frequency of 434.550 Mhz, and channels are spaced every
620 100 khz. Thus, channel 1 is 434.650 Mhz, and channel 9 is 435.550 Mhz.
621 At any given launch, we highly recommend coordinating who will use
622 each channel and when to avoid interference. And of course, both
623 TeleMetrum and TeleDongle must be configured to the same channel to
624 successfully communicate with each other.
627 To set the radio channel, use the 'c r' command, like 'c r 3' to set
629 As with all 'c' sub-commands, follow this with a 'c w' to write the
630 change to the parameter block in the on-board DataFlash chip on
631 your TeleMetrum board if you want the change to stay in place across reboots.
635 <title>Apogee Delay</title>
637 Apogee delay is the number of seconds after TeleMetrum detects flight
638 apogee that the drogue charge should be fired. In most cases, this
639 should be left at the default of 0. However, if you are flying
640 redundant electronics such as for an L3 certification, you may wish
641 to set one of your altimeters to a positive delay so that both
642 primary and backup pyrotechnic charges do not fire simultaneously.
645 To set the apogee delay, use the [FIXME] command.
646 As with all 'c' sub-commands, follow this with a 'c w' to write the
647 change to the parameter block in the on-board DataFlash chip.
650 Please note that the TeleMetrum apogee detection algorithm always
651 fires a fraction of a second *after* apogee. If you are also flying
652 an altimeter like the PerfectFlite MAWD, which only supports selecting
653 0 or 1 seconds of apogee delay, you may wish to set the MAWD to 0
654 seconds delay and set the TeleMetrum to fire your backup 2 or 3
655 seconds later to avoid any chance of both charges firing
656 simultaneously. We've flown several airframes this way quite happily,
657 including Keith's successful L3 cert.
661 <title>Main Deployment Altitude</title>
663 By default, TeleMetrum will fire the main deployment charge at an
664 elevation of 250 meters (about 820 feet) above ground. We think this
665 is a good elevation for most airframes, but feel free to change this
666 to suit. In particular, if you are flying two altimeters, you may
668 deployment elevation for the backup altimeter to be something lower
669 than the primary so that both pyrotechnic charges don't fire
673 To set the main deployment altitude, use the [FIXME] command.
674 As with all 'c' sub-commands, follow this with a 'c w' to write the
675 change to the parameter block in the on-board DataFlash chip.
680 <title>Calibration</title>
682 There are only two calibrations required for a TeleMetrum board, and
683 only one for TeleDongle.
686 <title>Radio Frequency</title>
688 The radio frequency is synthesized from a clock based on the 48 Mhz
689 crystal on the board. The actual frequency of this oscillator must be
690 measured to generate a calibration constant. While our GFSK modulation
691 bandwidth is wide enough to allow boards to communicate even when
692 their oscillators are not on exactly the same frequency, performance
693 is best when they are closely matched.
694 Radio frequency calibration requires a calibrated frequency counter.
695 Fortunately, once set, the variation in frequency due to aging and
696 temperature changes is small enough that re-calibration by customers
697 should generally not be required.
700 To calibrate the radio frequency, connect the UHF antenna port to a
701 frequency counter, set the board to channel 0, and use the 'C'
702 command to generate a CW carrier. Wait for the transmitter temperature
703 to stabilize and the frequency to settle down.
704 Then, divide 434.550 Mhz by the
705 measured frequency and multiply by the current radio cal value show
706 in the 'c s' command. For an unprogrammed board, the default value
707 is 1186611. Take the resulting integer and program it using the 'c f'
708 command. Testing with the 'C' command again should show a carrier
709 within a few tens of Hertz of the intended frequency.
710 As with all 'c' sub-commands, follow this with a 'c w' to write the
711 change to the parameter block in the on-board DataFlash chip.
715 <title>Accelerometer</title>
717 The accelerometer we use has its own 5 volt power supply and
718 the output must be passed through a resistive voltage divider to match
719 the input of our 3.3 volt ADC. This means that unlike the barometric
720 sensor, the output of the acceleration sensor is not ratiometric to
721 the ADC converter, and calibration is required. We also support the
722 use of any of several accelerometers from a Freescale family that
723 includes at least +/- 40g, 50g, 100g, and 200g parts. Using gravity,
724 a simple 2-point calibration yields acceptable results capturing both
725 the different sensitivities and ranges of the different accelerometer
726 parts and any variation in power supply voltages or resistor values
727 in the divider network.
730 To calibrate the acceleration sensor, use the 'c a 0' command. You
731 will be prompted to orient the board vertically with the UHF antenna
732 up and press a key, then to orient the board vertically with the
733 UHF antenna down and press a key.
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.
738 The +1g and -1g calibration points are included in each telemetry
739 frame and are part of the header extracted by ao-dumplog after flight.
740 Note that we always store and return raw ADC samples for each
741 sensor... nothing is permanently "lost" or "damaged" if the
745 In the unlikely event an accel cal that goes badly, it is possible
746 that TeleMetrum may always come up in 'pad mode' and as such not be
747 listening to either the USB or radio interfaces. If that happens,
748 there is a special hook in the firmware to force the board back
749 in to 'idle mode' so you can re-do the cal. To use this hook, you
750 just need to ground the SPI clock pin at power-on. This pin is
751 available as pin 2 on the 8-pin companion connector, and pin 1 is
752 ground. So either carefully install a fine-gauge wire jumper
753 between the two pins closest to the index hole end of the 8-pin
754 connector, or plug in the programming cable to the 8-pin connector
755 and use a small screwdriver or similar to short the two pins closest
756 to the index post on the 4-pin end of the programming cable, and
757 power up the board. It should come up in 'idle mode' (two beeps).
765 <title>Updating Device Firmware</title>
767 The big conceptual thing to realize is that you have to use a
768 TeleDongle as a programmer to update a TeleMetrum, and vice versa.
769 Due to limited memory resources in the cc1111, we don't support
770 programming either unit directly over USB.
773 You may wish to begin by ensuring you have current firmware images.
774 These are distributed as part of the AltOS software bundle that
775 also includes the AltosUI ground station program. Newer ground
776 station versions typically work fine with older firmware versions,
777 so you don't need to update your devices just to try out new
778 software features. You can always download the most recent
779 version from http://www.altusmetrum.org/AltOS/.
782 We recommend updating TeleMetrum first, before updating TeleDongle.
785 <title>Updating TeleMetrum Firmware</title>
786 <orderedlist inheritnum='inherit' numeration='arabic'>
788 Find the 'programming cable' that you got as part of the starter
789 kit, that has a red 8-pin MicroMaTch connector on one end and a
790 red 4-pin MicroMaTch connector on the other end.
793 Take the 2 screws out of the TeleDongle case to get access
794 to the circuit board.
797 Plug the 8-pin end of the programming cable to the
798 matching connector on the TeleDongle, and the 4-pin end to the
799 matching connector on the TeleMetrum.
800 Note that each MicroMaTch connector has an alignment pin that
801 goes through a hole in the PC board when you have the cable
805 Attach a battery to the TeleMetrum board.
808 Plug the TeleDongle into your computer's USB port, and power
812 Run AltosUI, and select 'Flash Image' from the File menu.
815 Pick the TeleDongle device from the list, identifying it as the
819 Select the image you want put on the TeleMetrum, which should have a
820 name in the form telemetrum-v1.0-0.7.1.ihx. It should be visible
821 in the default directory, if not you may have to poke around
822 your system to find it.
825 Make sure the configuration parameters are reasonable
826 looking. If the serial number and/or RF configuration
827 values aren't right, you'll need to change them.
830 Hit the 'OK' button and the software should proceed to flash
831 the TeleMetrum with new firmware, showing a progress bar.
834 Confirm that the TeleMetrum board seems to have updated ok, which you
835 can do by plugging in to it over USB and using a terminal program
836 to connect to the board and issue the 'v' command to check
840 If something goes wrong, give it another try.
845 <title>Updating TeleDongle Firmware</title>
847 Updating TeleDongle's firmware is just like updating TeleMetrum
848 firmware, but you switch which board is the programmer and which
849 is the programming target.
851 <orderedlist inheritnum='inherit' numeration='arabic'>
853 Find the 'programming cable' that you got as part of the starter
854 kit, that has a red 8-pin MicroMaTch connector on one end and a
855 red 4-pin MicroMaTch connector on the other end.
858 Find the USB cable that you got as part of the starter kit, and
859 plug the "mini" end in to the mating connector on TeleMetrum.
862 Take the 2 screws out of the TeleDongle case to get access
863 to the circuit board.
866 Plug the 8-pin end of the programming cable to the (latching)
867 matching connector on the TeleMetrum, and the 4-pin end to the
868 matching connector on the TeleDongle.
869 Note that each MicroMaTch connector has an alignment pin that
870 goes through a hole in the PC board when you have the cable
874 Attach a battery to the TeleMetrum board.
877 Plug both TeleMetrum and TeleDongle into your computer's USB
878 ports, and power up the TeleMetrum.
881 Run AltosUI, and select 'Flash Image' from the File menu.
884 Pick the TeleMetrum device from the list, identifying it as the
888 Select the image you want put on the TeleDongle, which should have a
889 name in the form teledongle-v0.2-0.7.1.ihx. It should be visible
890 in the default directory, if not you may have to poke around
891 your system to find it.
894 Make sure the configuration parameters are reasonable
895 looking. If the serial number and/or RF configuration
896 values aren't right, you'll need to change them. The TeleDongle
897 serial number is on the "bottom" of the circuit board, and can
898 usually be read through the translucent blue plastic case without
899 needing to remove the board from the case.
902 Hit the 'OK' button and the software should proceed to flash
903 the TeleDongle with new firmware, showing a progress bar.
906 Confirm that the TeleDongle board seems to have updated ok, which you
907 can do by plugging in to it over USB and using a terminal program
908 to connect to the board and issue the 'v' command to check
909 the version, etc. Once you're happy, remove the programming cable
910 and put the cover back on the TeleDongle.
913 If something goes wrong, give it another try.
917 Be careful removing the programming cable from the locking 8-pin
918 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
919 screwdriver or knife blade to gently pry the locking ears out
920 slightly to extract the connector. We used a locking connector on
921 TeleMetrum to help ensure that the cabling to companion boards
922 used in a rocket don't ever come loose accidentally in flight.
932 <title>AltosUI</title>
934 The AltosUI program provides a graphical user interface for
935 interacting with the Altus Metrum product family, including
936 TeleMetrum and TeleDongle. AltosUI can monitor telemetry data,
937 configure TeleMetrum and TeleDongle devices and many other
938 tasks. The primary interface window provides a selection of
939 buttons, one for each major activity in the system. This manual
940 is split into chapters, each of which documents one of the tasks
941 provided from the top-level toolbar.
944 <title>Packet Command Mode</title>
945 <subtitle>Controlling TeleMetrum Over The Radio Link</subtitle>
947 One of the unique features of the Altos Metrum environment is
948 the ability to create a two way command link between TeleDongle
949 and TeleMetrum using the digital radio transceivers built into
950 each device. This allows you to interact with TeleMetrum from
951 afar, as if it were directly connected to the computer.
954 Any operation which can be performed with TeleMetrum
955 can either be done with TeleMetrum directly connected to
956 the computer via the USB cable, or through the packet
957 link. Simply select the appropriate TeleDongle device when
958 the list of devices is presented and AltosUI will use packet
964 Save Flight Data—Recover flight data from the rocket without
970 Configure TeleMetrum—Reset apogee delays or main deploy
971 heights to respond to changing launch conditions. You can
972 also 'reboot' the TeleMetrum device. Use this to remotely
973 enable the flight computer by turning TeleMetrum on while
974 horizontal, then once the airframe is oriented for launch,
975 you can reboot TeleMetrum and have it restart in pad mode
976 without having to climb the scary ladder.
981 Fire Igniters—Test your deployment charges without snaking
982 wires out through holes in the airframe. Simply assembly the
983 rocket as if for flight with the apogee and main charges
984 loaded, then remotely command TeleMetrum to fire the
990 Packet command mode uses the same RF channels as telemetry
991 mode. Configure the desired TeleDongle channel using the
992 flight monitor window channel selector and then close that
993 window before performing the desired operation.
996 TeleMetrum only enables packet command mode in 'idle' mode, so
997 make sure you have TeleMetrum lying horizontally when you turn
998 it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
999 flight and will not be listening for command packets from TeleDongle.
1002 When packet command mode is enabled, you can monitor the link
1003 by watching the lights on the TeleDongle and TeleMetrum
1004 devices. The red LED will flash each time TeleDongle or
1005 TeleMetrum transmit a packet while the green LED will light up
1006 on TeleDongle while it is waiting to receive a packet from
1011 <title>Monitor Flight</title>
1012 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
1014 Selecting this item brings up a dialog box listing all of the
1015 connected TeleDongle devices. When you choose one of these,
1016 AltosUI will create a window to display telemetry data as
1017 received by the selected TeleDongle device.
1020 All telemetry data received are automatically recorded in
1021 suitable log files. The name of the files includes the current
1022 date and rocket serial and flight numbers.
1025 The radio channel being monitored by the TeleDongle device is
1026 displayed at the top of the window. You can configure the
1027 channel by clicking on the channel box and selecting the desired
1028 channel. AltosUI remembers the last channel selected for each
1029 TeleDongle and selects that automatically the next time you use
1033 Below the TeleDongle channel selector, the window contains a few
1034 significant pieces of information about the TeleMetrum providing
1035 the telemetry data stream:
1039 <para>The TeleMetrum callsign</para>
1042 <para>The TeleMetrum serial number</para>
1045 <para>The flight number. Each TeleMetrum remembers how many
1051 The rocket flight state. Each flight passes through several
1052 states including Pad, Boost, Fast, Coast, Drogue, Main and
1058 The Received Signal Strength Indicator value. This lets
1059 you know how strong a signal TeleDongle is receiving. The
1060 radio inside TeleDongle operates down to about -99dBm;
1061 weaker signals may not be receiveable. The packet link uses
1062 error correction and detection techniques which prevent
1063 incorrect data from being reported.
1068 Finally, the largest portion of the window contains a set of
1069 tabs, each of which contain some information about the rocket.
1070 They're arranged in 'flight order' so that as the flight
1071 progresses, the selected tab automatically switches to display
1072 data relevant to the current state of the flight. You can select
1073 other tabs at any time. The final 'table' tab contains all of
1074 the telemetry data in one place.
1077 <title>Launch Pad</title>
1079 The 'Launch Pad' tab shows information used to decide when the
1080 rocket is ready for flight. The first elements include red/green
1081 indicators, if any of these is red, you'll want to evaluate
1082 whether the rocket is ready to launch:
1086 Battery Voltage. This indicates whether the LiPo battery
1087 powering the TeleMetrum has sufficient charge to last for
1088 the duration of the flight. A value of more than
1089 3.7V is required for a 'GO' status.
1094 Apogee Igniter Voltage. This indicates whether the apogee
1095 igniter has continuity. If the igniter has a low
1096 resistance, then the voltage measured here will be close
1097 to the LiPo battery voltage. A value greater than 3.2V is
1098 required for a 'GO' status.
1103 Main Igniter Voltage. This indicates whether the main
1104 igniter has continuity. If the igniter has a low
1105 resistance, then the voltage measured here will be close
1106 to the LiPo battery voltage. A value greater than 3.2V is
1107 required for a 'GO' status.
1112 GPS Locked. This indicates whether the GPS receiver is
1113 currently able to compute position information. GPS requires
1114 at least 4 satellites to compute an accurate position.
1119 GPS Ready. This indicates whether GPS has reported at least
1120 10 consecutive positions without losing lock. This ensures
1121 that the GPS receiver has reliable reception from the
1127 The LaunchPad tab also shows the computed launch pad position
1128 and altitude, averaging many reported positions to improve the
1129 accuracy of the fix.
1134 <title>Ascent</title>
1136 This tab is shown during Boost, Fast and Coast
1137 phases. The information displayed here helps monitor the
1138 rocket as it heads towards apogee.
1141 The height, speed and acceleration are shown along with the
1142 maxium values for each of them. This allows you to quickly
1143 answer the most commonly asked questions you'll hear during
1147 The current latitude and longitude reported by the GPS are
1148 also shown. Note that under high acceleration, these values
1149 may not get updated as the GPS receiver loses position
1150 fix. Once the rocket starts coasting, the receiver should
1151 start reporting position again.
1154 Finally, the current igniter voltages are reported as in the
1155 Launch Pad tab. This can help diagnose deployment failures
1156 caused by wiring which comes loose under high acceleration.
1160 <title>Descent</title>
1162 Once the rocket has reached apogee and (we hope) activated the
1163 apogee charge, attention switches to tracking the rocket on
1164 the way back to the ground, and for dual-deploy flights,
1165 waiting for the main charge to fire.
1168 To monitor whether the apogee charge operated correctly, the
1169 current descent rate is reported along with the current
1170 height. Good descent rates generally range from 15-30m/s.
1173 To help locate the rocket in the sky, use the elevation and
1174 bearing information to figure out where to look. Elevation is
1175 in degrees above the horizon. Bearing is reported in degrees
1176 relative to true north. Range can help figure out how big the
1177 rocket will appear. Note that all of these values are relative
1178 to the pad location. If the elevation is near 90°, the rocket
1179 is over the pad, not over you.
1182 Finally, the igniter voltages are reported in this tab as
1183 well, both to monitor the main charge as well as to see what
1184 the status of the apogee charge is.
1188 <title>Landed</title>
1190 Once the rocket is on the ground, attention switches to
1191 recovery. While the radio signal is generally lost once the
1192 rocket is on the ground, the last reported GPS position is
1193 generally within a short distance of the actual landing location.
1196 The last reported GPS position is reported both by
1197 latitude and longitude as well as a bearing and distance from
1198 the launch pad. The distance should give you a good idea of
1199 whether you'll want to walk or hitch a ride. Take the reported
1200 latitude and longitude and enter them into your handheld GPS
1201 unit and have that compute a track to the landing location.
1204 Finally, the maximum height, speed and acceleration reported
1205 during the flight are displayed for your admiring observers.
1209 <title>Site Map</title>
1211 When the rocket gets a GPS fix, the Site Map tab will map
1212 the rocket's position to make it easier for you to locate the
1213 rocket, both while it is in the air, and when it has landed. The
1214 rocket's state is indicated by colour: white for pad, red for
1215 boost, pink for fast, yellow for coast, light blue for drogue,
1216 dark blue for main, and black for landed.
1219 The map's scale is approximately 3m (10ft) per pixel. The map
1220 can be dragged using the left mouse button. The map will attempt
1221 to keep the rocket roughly centred while data is being received.
1224 Images are fetched automatically via the Google Maps Static API,
1225 and are cached for reuse. If map images cannot be downloaded,
1226 the rocket's path will be traced on a dark grey background
1232 <title>Save Flight Data</title>
1234 TeleMetrum records flight data to its internal flash memory.
1235 This data is recorded at a much higher rate than the telemetry
1236 system can handle, and is not subject to radio drop-outs. As
1237 such, it provides a more complete and precise record of the
1238 flight. The 'Save Flight Data' button allows you to read the
1239 flash memory and write it to disk.
1242 Clicking on the 'Save Flight Data' button brings up a list of
1243 connected TeleMetrum and TeleDongle devices. If you select a
1244 TeleMetrum device, the flight data will be downloaded from that
1245 device directly. If you select a TeleDongle device, flight data
1246 will be downloaded from a TeleMetrum device connected via the
1247 packet command link to the specified TeleDongle. See the chapter
1248 on Packet Command Mode for more information about this.
1251 The filename for the data is computed automatically from the recorded
1252 flight date, TeleMetrum serial number and flight number
1257 <title>Replay Flight</title>
1259 Select this button and you are prompted to select a flight
1260 record file, either a .telem file recording telemetry data or a
1261 .eeprom file containing flight data saved from the TeleMetrum
1265 Once a flight record is selected, the flight monitor interface
1266 is displayed and the flight is re-enacted in real time. Check
1267 the Monitor Flight chapter above to learn how this window operates.
1271 <title>Graph Data</title>
1273 Select this button and you are prompted to select a flight
1274 record file, either a .telem file recording telemetry data or a
1275 .eeprom file containing flight data saved from the TeleMetrum
1279 Once a flight record is selected, the acceleration (blue),
1280 velocity (green) and altitude (red) of the flight are plotted and
1281 displayed, measured in metric units.
1284 The graph can be zoomed into a particular area by clicking and
1285 dragging down and to the right. Once zoomed, the graph can be
1286 reset by clicking and dragging up and to the left. Holding down
1287 control and clicking and dragging allows the graph to be panned.
1288 The right mouse button causes a popup menu to be displayed, giving
1289 you the option save or print the plot.
1292 Note that telemetry files will generally produce poor graphs
1293 due to the lower sampling rate and missed telemetry packets,
1294 and will also often have significant amounts of data received
1295 while the rocket was waiting on the pad. Use saved flight data
1296 for graphing where possible.
1300 <title>Export Data</title>
1302 This tool takes the raw data files and makes them available for
1303 external analysis. When you select this button, you are prompted to select a flight
1304 data file (either .eeprom or .telem will do, remember that
1305 .eeprom files contain higher resolution and more continuous
1306 data). Next, a second dialog appears which is used to select
1307 where to write the resulting file. It has a selector to choose
1308 between CSV and KML file formats.
1311 <title>Comma Separated Value Format</title>
1313 This is a text file containing the data in a form suitable for
1314 import into a spreadsheet or other external data analysis
1315 tool. The first few lines of the file contain the version and
1316 configuration information from the TeleMetrum device, then
1317 there is a single header line which labels all of the
1318 fields. All of these lines start with a '#' character which
1319 most tools can be configured to skip over.
1322 The remaining lines of the file contain the data, with each
1323 field separated by a comma and at least one space. All of
1324 the sensor values are converted to standard units, with the
1325 barometric data reported in both pressure, altitude and
1326 height above pad units.
1330 <title>Keyhole Markup Language (for Google Earth)</title>
1332 This is the format used by
1333 Googleearth to provide an overlay within that
1334 application. With this, you can use Googleearth to see the
1335 whole flight path in 3D.
1340 <title>Configure TeleMetrum</title>
1342 Select this button and then select either a TeleMetrum or
1343 TeleDongle Device from the list provided. Selecting a TeleDongle
1344 device will use Packet Comamnd Mode to configure remote
1345 TeleMetrum device. Learn how to use this in the Packet Command
1349 The first few lines of the dialog provide information about the
1350 connected TeleMetrum device, including the product name,
1351 software version and hardware serial number. Below that are the
1352 individual configuration entries.
1355 At the bottom of the dialog, there are four buttons:
1360 Save. This writes any changes to the TeleMetrum
1361 configuration parameter block in flash memory. If you don't
1362 press this button, any changes you make will be lost.
1367 Reset. This resets the dialog to the most recently saved values,
1368 erasing any changes you have made.
1373 Reboot. This reboots the TeleMetrum device. Use this to
1374 switch from idle to pad mode by rebooting once the rocket is
1375 oriented for flight.
1380 Close. This closes the dialog. Any unsaved changes will be
1386 The rest of the dialog contains the parameters to be configured.
1389 <title>Main Deploy Altitude</title>
1391 This sets the altitude (above the recorded pad altitude) at
1392 which the 'main' igniter will fire. The drop-down menu shows
1393 some common values, but you can edit the text directly and
1394 choose whatever you like. If the apogee charge fires below
1395 this altitude, then the main charge will fire two seconds
1396 after the apogee charge fires.
1400 <title>Apogee Delay</title>
1402 When flying redundant electronics, it's often important to
1403 ensure that multiple apogee charges don't fire at precisely
1404 the same time as that can overpressurize the apogee deployment
1405 bay and cause a structural failure of the airframe. The Apogee
1406 Delay parameter tells the flight computer to fire the apogee
1407 charge a certain number of seconds after apogee has been
1412 <title>Radio Channel</title>
1414 This configures which of the 10 radio channels to use for both
1415 telemetry and packet command mode. Note that if you set this
1416 value via packet command mode, you will have to reconfigure
1417 the TeleDongle channel before you will be able to use packet
1422 <title>Radio Calibration</title>
1424 The radios in every Altus Metrum device are calibrated at the
1425 factory to ensure that they transmit and receive on the
1426 specified frequency for each channel. You can adjust that
1427 calibration by changing this value. To change the TeleDongle's
1428 calibration, you must reprogram the unit completely.
1432 <title>Callsign</title>
1434 This sets the callsign included in each telemetry packet. Set this
1435 as needed to conform to your local radio regulations.
1440 <title>Configure AltosUI</title>
1442 This button presents a dialog so that you can configure the AltosUI global settings.
1445 <title>Voice Settings</title>
1447 AltosUI provides voice annoucements during flight so that you
1448 can keep your eyes on the sky and still get information about
1449 the current flight status. However, sometimes you don't want
1454 <para>Enable—turns all voice announcements on and off</para>
1458 Test Voice—Plays a short message allowing you to verify
1459 that the audio systme is working and the volume settings
1466 <title>Log Directory</title>
1468 AltosUI logs all telemetry data and saves all TeleMetrum flash
1469 data to this directory. This directory is also used as the
1470 staring point when selecting data files for display or export.
1473 Click on the directory name to bring up a directory choosing
1474 dialog, select a new directory and click 'Select Directory' to
1475 change where AltosUI reads and writes data files.
1479 <title>Callsign</title>
1481 This value is used in command packet mode and is transmitted
1482 in each packet sent from TeleDongle and received from
1483 TeleMetrum. It is not used in telemetry mode as that transmits
1484 packets only from TeleMetrum to TeleDongle. Configure this
1485 with the AltosUI operators callsign as needed to comply with
1486 your local radio regulations.
1491 <title>Flash Image</title>
1493 This reprograms any Altus Metrum device by using a TeleMetrum or
1494 TeleDongle as a programming dongle. Please read the directions
1495 for connecting the programming cable in the main TeleMetrum
1496 manual before reading these instructions.
1499 Once you have the programmer and target devices connected,
1500 push the 'Flash Image' button. That will present a dialog box
1501 listing all of the connected devices. Carefully select the
1502 programmer device, not the device to be programmed.
1505 Next, select the image to flash to the device. These are named
1506 with the product name and firmware version. The file selector
1507 will start in the directory containing the firmware included
1508 with the AltosUI package. Navigate to the directory containing
1509 the desired firmware if it isn't there.
1512 Next, a small dialog containing the device serial number and
1513 RF calibration values should appear. If these values are
1514 incorrect (possibly due to a corrupted image in the device),
1515 enter the correct values here.
1518 Finally, a dialog containing a progress bar will follow the
1519 programming process.
1522 When programming is complete, the target device will
1523 reboot. Note that if the target device is connected via USB, you
1524 will have to unplug it and then plug it back in for the USB
1525 connection to reset so that you can communicate with the device
1530 <title>Fire Igniter</title>
1536 <title>Using Altus Metrum Products</title>
1538 <title>Being Legal</title>
1540 First off, in the US, you need an [amateur radio license](../Radio) or
1541 other authorization to legally operate the radio transmitters that are part
1545 <title>In the Rocket</title>
1547 In the rocket itself, you just need a [TeleMetrum](../TeleMetrum) board and
1548 a LiPo rechargeable battery. An 860mAh battery weighs less than a 9V
1549 alkaline battery, and will run a [TeleMetrum](../TeleMetrum) for hours.
1552 By default, we ship TeleMetrum with a simple wire antenna. If your
1553 electronics bay or the airframe it resides within is made of carbon fiber,
1554 which is opaque to RF signals, you may choose to have an SMA connector
1555 installed so that you can run a coaxial cable to an antenna mounted
1556 elsewhere in the rocket.
1560 <title>On the Ground</title>
1562 To receive the data stream from the rocket, you need an antenna and short
1563 feedline connected to one of our [TeleDongle](../TeleDongle) units. The
1564 TeleDongle in turn plugs directly into the USB port on a notebook
1565 computer. Because TeleDongle looks like a simple serial port, your computer
1566 does not require special device drivers... just plug it in.
1569 Right now, all of our application software is written for Linux. However,
1570 because we understand that many people run Windows or MacOS, we are working
1571 on a new ground station program written in Java that should work on all
1575 After the flight, you can use the RF link to extract the more detailed data
1576 logged in the rocket, or you can use a mini USB cable to plug into the
1577 TeleMetrum board directly. Pulling out the data without having to open up
1578 the rocket is pretty cool! A USB cable is also how you charge the LiPo
1579 battery, so you'll want one of those anyway... the same cable used by lots
1580 of digital cameras and other modern electronic stuff will work fine.
1583 If your rocket lands out of sight, you may enjoy having a hand-held GPS
1584 receiver, so that you can put in a waypoint for the last reported rocket
1585 position before touch-down. This makes looking for your rocket a lot like
1586 Geo-Cacheing... just go to the waypoint and look around starting from there.
1589 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
1590 can use that with your antenna to direction-find the rocket on the ground
1591 the same way you can use a Walston or Beeline tracker. This can be handy
1592 if the rocket is hiding in sage brush or a tree, or if the last GPS position
1593 doesn't get you close enough because the rocket dropped into a canyon, or
1594 the wind is blowing it across a dry lake bed, or something like that... Keith
1595 and Bdale both currently own and use the Yaesu VX-7R at launches.
1598 So, to recap, on the ground the hardware you'll need includes:
1599 <orderedlist inheritnum='inherit' numeration='arabic'>
1601 an antenna and feedline
1610 optionally, a handheld GPS receiver
1613 optionally, an HT or receiver covering 435 Mhz
1618 The best hand-held commercial directional antennas we've found for radio
1619 direction finding rockets are from
1620 <ulink url="http://www.arrowantennas.com/" >
1623 The 440-3 and 440-5 are both good choices for finding a
1624 TeleMetrum-equipped rocket when used with a suitable 70cm HT.
1628 <title>Data Analysis</title>
1630 Our software makes it easy to log the data from each flight, both the
1631 telemetry received over the RF link during the flight itself, and the more
1632 complete data log recorded in the DataFlash memory on the TeleMetrum
1633 board. Once this data is on your computer, our postflight tools make it
1634 easy to quickly get to the numbers everyone wants, like apogee altitude,
1635 max acceleration, and max velocity. You can also generate and view a
1636 standard set of plots showing the altitude, acceleration, and
1637 velocity of the rocket during flight. And you can even export a data file
1638 useable with Google Maps and Google Earth for visualizing the flight path
1639 in two or three dimensions!
1642 Our ultimate goal is to emit a set of files for each flight that can be
1643 published as a web page per flight, or just viewed on your local disk with
1648 <title>Future Plans</title>
1650 In the future, we intend to offer "companion boards" for the rocket that will
1651 plug in to TeleMetrum to collect additional data, provide more pyro channels,
1652 and so forth. A reference design for a companion board will be documented
1653 soon, and will be compatible with open source Arduino programming tools.
1656 We are also working on the design of a hand-held ground terminal that will
1657 allow monitoring the rocket's status, collecting data during flight, and
1658 logging data after flight without the need for a notebook computer on the
1659 flight line. Particularly since it is so difficult to read most notebook
1660 screens in direct sunlight, we think this will be a great thing to have.
1663 Because all of our work is open, both the hardware designs and the software,
1664 if you have some great idea for an addition to the current Altus Metrum family,
1665 feel free to dive in and help! Or let us know what you'd like to see that
1666 we aren't already working on, and maybe we'll get excited about it too...