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5 <title>The Altus Metrum System</title>
6 <subtitle>An Owner's Manual for TeleMetrum, TeleMini and TeleDongle Devices</subtitle>
9 <firstname>Bdale</firstname>
10 <surname>Garbee</surname>
13 <firstname>Keith</firstname>
14 <surname>Packard</surname>
17 <firstname>Bob</firstname>
18 <surname>Finch</surname>
21 <firstname>Anthony</firstname>
22 <surname>Towns</surname>
26 <holder>Bdale Garbee and Keith Packard</holder>
30 This document is released under the terms of the
31 <ulink url="http://creativecommons.org/licenses/by-sa/3.0/">
32 Creative Commons ShareAlike 3.0
39 <revnumber>1.0</revnumber>
40 <date>24 August 2011</date>
42 Updated for software version 1.0. Note that 1.0 represents a
43 telemetry format change, meaning both ends of a link
44 (TeleMetrum/TeleMini and TeleDongle) must be updated or
45 communications will fail.
49 <revnumber>0.9</revnumber>
50 <date>18 January 2011</date>
52 Updated for software version 0.9. Note that 0.9 represents a
53 telemetry format change, meaning both ends of a link (TeleMetrum and
54 TeleDongle) must be updated or communications will fail.
58 <revnumber>0.8</revnumber>
59 <date>24 November 2010</date>
60 <revremark>Updated for software version 0.8 </revremark>
66 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing "The
67 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
68 Kit" which formed the basis of the original Getting Started chapter
69 in this manual. Bob was one of our first customers for a production
70 TeleMetrum, and his continued enthusiasm and contributions
71 are immensely gratifying and highly appreciated!
74 And thanks to Anthony (AJ) Towns for major contributions including
75 the AltosUI graphing and site map code and associated documentation.
76 Free software means that our customers and friends can become our
77 collaborators, and we certainly appreciate this level of
81 Have fun using these products, and we hope to meet all of you
82 out on the rocket flight line somewhere.
85 NAR #87103, TRA #12201
88 NAR #88757, TRA #12200
93 <title>Introduction and Overview</title>
95 Welcome to the Altus Metrum community! Our circuits and software reflect
96 our passion for both hobby rocketry and Free Software. We hope their
97 capabilities and performance will delight you in every way, but by
98 releasing all of our hardware and software designs under open licenses,
99 we also hope to empower you to take as active a role in our collective
103 The first device created for our community was TeleMetrum, a dual
104 deploy altimeter with fully integrated GPS and radio telemetry
105 as standard features, and a "companion interface" that will
106 support optional capabilities in the future.
109 The newest device is TeleMini, a dual deploy altimeter with
110 radio telemetry and radio direction finding. This device is only
111 13mm by 38mm (½ inch by 1½ inches) and can fit easily in an 18mm
115 Complementing TeleMetrum and TeleMini is TeleDongle, a USB to RF
116 interface for communicating with the altimeters. Combined with your
117 choice of antenna and
118 notebook computer, TeleDongle and our associated user interface software
119 form a complete ground station capable of logging and displaying in-flight
120 telemetry, aiding rocket recovery, then processing and archiving flight
121 data for analysis and review.
124 More products will be added to the Altus Metrum family over time, and
125 we currently envision that this will be a single, comprehensive manual
126 for the entire product family.
130 <title>Getting Started</title>
132 The first thing to do after you check the inventory of parts in your
133 "starter kit" is to charge the battery.
136 The TeleMetrum battery can be charged by plugging it into the
137 corresponding socket of the TeleMetrum and then using the USB A to
139 cable to plug the TeleMetrum into your computer's USB socket. The
140 TeleMetrum circuitry will charge the battery whenever it is plugged
141 in, because the TeleMetrum's on-off switch does NOT control the
145 When the GPS chip is initially searching for
146 satellites, TeleMetrum will consume more current than it can pull
147 from the USB port, so the battery must be attached in order to get
148 satellite lock. Once GPS is locked, the current consumption goes back
149 down enough to enable charging while
150 running. So it's a good idea to fully charge the battery as your
151 first item of business so there is no issue getting and maintaining
152 satellite lock. The yellow charge indicator led will go out when the
153 battery is nearly full and the charger goes to trickle charge. It
154 can take several hours to fully recharge a deeply discharged battery.
157 The TeleMini battery can be charged by disconnecting it from the
158 TeleMini board and plugging it into a standalone battery charger
159 board, and connecting that via a USB cable to a laptop or other USB
163 The other active device in the starter kit is the TeleDongle USB to
164 RF interface. If you plug it in to your Mac or Linux computer it should
165 "just work", showing up as a serial port device. Windows systems need
166 driver information that is part of the AltOS download to know that the
167 existing USB modem driver will work. We therefore recommend installing
168 our software before plugging in TeleDongle if you are using a Windows
169 computer. If you are using Linux and are having problems, try moving
170 to a fresher kernel (2.6.33 or newer), as the USB serial driver had
171 ugly bugs in some earlier versions.
174 Next you should obtain and install the AltOS software. These include
175 the AltosUI ground station program, current firmware images for
176 TeleMetrum, TeleMini and TeleDongle, and a number of standalone
177 utilities that are rarely needed. Pre-built binary packages are
178 available for Linux, Microsoft Windows, and recent MacOSX versions.
179 Full source code and build instructions are also available.
180 The latest version may always be downloaded from
181 <ulink url="http://altusmetrum.org/AltOS"/>.
185 <title>Handling Precautions</title>
187 All Altus Metrum products are sophisticated electronic devices.
188 When handled gently and properly installed in an air-frame, they
189 will deliver impressive results. However, as with all electronic
190 devices, there are some precautions you must take.
193 The Lithium Polymer rechargeable batteries have an
194 extraordinary power density. This is great because we can fly with
195 much less battery mass than if we used alkaline batteries or previous
196 generation rechargeable batteries... but if they are punctured
197 or their leads are allowed to short, they can and will release their
199 Thus we recommend that you take some care when handling our batteries
200 and consider giving them some extra protection in your air-frame. We
201 often wrap them in suitable scraps of closed-cell packing foam before
202 strapping them down, for example.
205 The barometric sensors used on both TeleMetrum and TeleMini are
206 sensitive to sunlight. In normal TeleMetrum mounting situations, it
207 and all of the other surface mount components
208 are "down" towards whatever the underlying mounting surface is, so
209 this is not normally a problem. Please consider this, though, when
210 designing an installation, for example, in an air-frame with a
211 see-through plastic payload bay. It is particularly important to
212 consider this with TeleMini, both because the baro sensor is on the
213 "top" of the board, and because many model rockets with payload bays
214 use clear plastic for the payload bay! Replacing these with an opaque
215 cardboard tube, painting them, or wrapping them with a layer of masking
216 tape are all reasonable approaches to keep the sensor out of direct
220 The barometric sensor sampling port must be able to "breathe",
221 both by not being covered by foam or tape or other materials that might
222 directly block the hole on the top of the sensor, and also by having a
223 suitable static vent to outside air.
226 As with all other rocketry electronics, Altus Metrum altimeters must
227 be protected from exposure to corrosive motor exhaust and ejection
232 <title>Hardware Overview</title>
234 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
235 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
236 small in diameter may require some creativity in mounting and wiring
237 to succeed! The presence of an accelerometer means TeleMetrum should
238 be aligned along the flight axis of the airframe, and by default the 1/4
239 wave UHF wire antenna should be on the nose-cone end of the board. The
240 antenna wire is about 7 inches long, and wiring for a power switch and
241 the e-matches for apogee and main ejection charges depart from the
242 fin can end of the board, meaning an ideal "simple" avionics
243 bay for TeleMetrum should have at least 10 inches of interior length.
246 TeleMini is a 0.5 inch by 1.5 inch circuit board. It was designed to
247 fit inside an 18mm air-frame tube, but using it in a tube that
248 small in diameter may require some creativity in mounting and wiring
249 to succeed! Since there is no accelerometer, TeleMini can be mounted
250 in any convenient orientation. The default 1/4
251 wave UHF wire antenna attached to the center of one end of
252 the board is about 7 inches long, and wiring for a power switch and
253 the e-matches for apogee and main ejection charges depart from the
254 other end of the board, meaning an ideal "simple" avionics
255 bay for TeleMini should have at least 9 inches of interior length.
258 A typical TeleMetrum or TeleMini installation involves attaching
259 only a suitable Lithium Polymer battery, a single pole switch for
260 power on/off, and two pairs of wires connecting e-matches for the
261 apogee and main ejection charges.
264 By default, we use the unregulated output of the Li-Po battery directly
265 to fire ejection charges. This works marvelously with standard
266 low-current e-matches like the J-Tek from MJG Technologies, and with
267 Quest Q2G2 igniters. However, if you want or need to use a separate
268 pyro battery, check out the "External Pyro Battery" section in this
269 manual for instructions on how to wire that up. The altimeters are
270 designed to work with an external pyro battery of no more than 15 volts.
273 Ejection charges are wired directly to the screw terminal block
274 at the aft end of the altimeter. You'll need a very small straight
275 blade screwdriver for these screws, such as you might find in a
276 jeweler's screwdriver set.
279 TeleMetrum also uses the screw terminal block for the power
280 switch leads. On TeleMini, the power switch leads are soldered
281 directly to the board and can be connected directly to a switch.
284 For most air-frames, the integrated antennas are more than
285 adequate. However, if you are installing in a carbon-fiber or
286 metal electronics bay which is opaque to RF signals, you may need to
287 use off-board external antennas instead. In this case, you can
288 order an altimeter with an SMA connector for the UHF antenna
289 connection, and, on TeleMetrum, you can unplug the integrated GPS
290 antenna and select an appropriate off-board GPS antenna with
291 cable terminating in a U.FL connector.
295 <title>System Operation</title>
297 <title>Firmware Modes </title>
299 The AltOS firmware build for the altimeters has two
300 fundamental modes, "idle" and "flight". Which of these modes
301 the firmware operates in is determined at start up time. For
302 TeleMetrum, the mode is controlled by the orientation of the
303 rocket (well, actually the board, of course...) at the time
304 power is switched on. If the rocket is "nose up", then
305 TeleMetrum assumes it's on a rail or rod being prepared for
306 launch, so the firmware chooses flight mode. However, if the
307 rocket is more or less horizontal, the firmware instead enters
308 idle mode. Since TeleMini doesn't have an accelerometer we can
309 use to determine orientation, "idle" mode is selected when the
310 board receives a command packet within the first five seconds
311 of operation; if no packet is received, the board enters
315 At power on, you will hear three beeps or see three flashes
316 ("S" in Morse code for start up) and then a pause while
317 the altimeter completes initialization and self test, and decides
318 which mode to enter next.
321 In flight or "pad" mode, the altimeter engages the flight
322 state machine, goes into transmit-only mode to
323 send telemetry, and waits for launch to be detected.
324 Flight mode is indicated by an "di-dah-dah-dit" ("P" for pad)
325 on the beeper or lights, followed by beeps or flashes
326 indicating the state of the pyrotechnic igniter continuity.
327 One beep/flash indicates apogee continuity, two beeps/flashes
328 indicate main continuity, three beeps/flashes indicate both
329 apogee and main continuity, and one longer "brap" sound or
330 rapidly alternating lights indicates no continuity. For a
331 dual deploy flight, make sure you're getting three beeps or
332 flashes before launching! For apogee-only or motor eject
333 flights, do what makes sense.
336 If idle mode is entered, you will hear an audible "di-dit" or see
337 two short flashes ("I" for idle), and the flight state machine is
338 disengaged, thus no ejection charges will fire. The altimeters also
339 listen for the radio link when in idle mode for requests sent via
340 TeleDongle. Commands can be issued to a TeleMetrum in idle mode
342 USB or the radio link equivalently. TeleMini only has the radio link.
343 Idle mode is useful for configuring the altimeter, for extracting data
344 from the on-board storage chip after flight, and for ground testing
348 One "neat trick" of particular value when TeleMetrum is used with
349 very large air-frames, is that you can power the board up while the
350 rocket is horizontal, such that it comes up in idle mode. Then you can
351 raise the air-frame to launch position, and issue a 'reset' command
352 via TeleDongle over the radio link to cause the altimeter to reboot and
353 come up in flight mode. This is much safer than standing on the top
354 step of a rickety step-ladder or hanging off the side of a launch
355 tower with a screw-driver trying to turn on your avionics before
362 TeleMetrum includes a complete GPS receiver. A complete explanation
363 of how GPS works is beyond the scope of this manual, but the bottom
364 line is that the TeleMetrum GPS receiver needs to lock onto at least
365 four satellites to obtain a solid 3 dimensional position fix and know
369 TeleMetrum provides backup power to the GPS chip any time a
370 battery is connected. This allows the receiver to "warm start" on
371 the launch rail much faster than if every power-on were a GPS
372 "cold start". In typical operations, powering up TeleMetrum
373 on the flight line in idle mode while performing final air-frame
374 preparation will be sufficient to allow the GPS receiver to cold
375 start and acquire lock. Then the board can be powered down during
376 RSO review and installation on a launch rod or rail. When the board
377 is turned back on, the GPS system should lock very quickly, typically
378 long before igniter installation and return to the flight line are
383 <title>Controlling An Altimeter Over The Radio Link</title>
385 One of the unique features of the Altus Metrum system is
386 the ability to create a two way command link between TeleDongle
387 and an altimeter using the digital radio transceivers built into
388 each device. This allows you to interact with the altimeter from
389 afar, as if it were directly connected to the computer.
392 Any operation which can be performed with TeleMetrum can
393 either be done with TeleMetrum directly connected to the
394 computer via the USB cable, or through the radio
395 link. TeleMini doesn't provide a USB connector and so it is
396 always communicated with over radio. Select the appropriate
397 TeleDongle device when the list of devices is presented and
398 AltosUI will interact with an altimeter over the radio link.
401 One oddity in the current interface is how AltosUI selects the
402 frequency for radio communications. Instead of providing
403 an interface to specifically configure the frequency, it uses
404 whatever frequency was most recently selected for the target
405 TeleDongle device in Monitor Flight mode. If you haven't ever
406 used that mode with the TeleDongle in question, select the
407 Monitor Flight button from the top level UI, and pick the
408 appropriate TeleDongle device. Once the flight monitoring
409 window is open, select the desired frequency and then close it
410 down again. All radio communications will now use that frequency.
415 Save Flight Data—Recover flight data from the rocket without
421 Configure altimeter apogee delays or main deploy heights
422 to respond to changing launch conditions. You can also
423 'reboot' the altimeter. Use this to remotely enable the
424 flight computer by turning TeleMetrum on in "idle" mode,
425 then once the air-frame is oriented for launch, you can
426 reboot the altimeter and have it restart in pad mode
427 without having to climb the scary ladder.
432 Fire Igniters—Test your deployment charges without snaking
433 wires out through holes in the air-frame. Simply assembly the
434 rocket as if for flight with the apogee and main charges
435 loaded, then remotely command the altimeter to fire the
441 Operation over the radio link for configuring an altimeter, ground
442 testing igniters, and so forth uses the same RF frequencies as flight
443 telemetry. To configure the desired TeleDongle frequency, select
444 the monitor flight tab, then use the frequency selector and
445 close the window before performing other desired radio operations.
448 TeleMetrum only enables radio commanding in 'idle' mode, so
449 make sure you have TeleMetrum lying horizontally when you turn
450 it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
451 flight, and will not be listening for command packets from TeleDongle.
454 TeleMini listens for a command packet for five seconds after
455 first being turned on, if it doesn't hear anything, it enters
456 'pad' mode, ready for flight and will no longer listen for
457 command packets. The easiest way to connect to TeleMini is to
458 initiate the command and select the TeleDongle device. At this
459 point, the TeleDongle will be attempting to communicate with
460 the TeleMini. Now turn TeleMini on, and it should immediately
461 start communicating with the TeleDongle and the desired
462 operation can be performed.
465 You can monitor the operation of the radio link by watching the
466 lights on the devices. The red LED will flash each time a packet
467 is tramsitted, while the green LED will light up on TeleDongle when
468 it is waiting to receive a packet from the altimeter.
472 <title>Ground Testing </title>
474 An important aspect of preparing a rocket using electronic deployment
475 for flight is ground testing the recovery system. Thanks
476 to the bi-directional radio link central to the Altus Metrum system,
477 this can be accomplished in a TeleMetrum or TeleMini equipped rocket
478 with less work than you may be accustomed to with other systems. It
482 Just prep the rocket for flight, then power up the altimeter
483 in "idle" mode (placing air-frame horizontal for TeleMetrum or
484 selected the Configure Altimeter tab for TeleMini). This will cause
485 the firmware to go into "idle" mode, in which the normal flight
486 state machine is disabled and charges will not fire without
487 manual command. You can now command the altimeter to fire the apogee
488 or main charges from a safe distance using your computer and
489 TeleDongle and the Fire Igniter tab to complete ejection testing.
493 <title>Radio Link </title>
495 The chip our boards are based on incorporates an RF transceiver, but
496 it's not a full duplex system... each end can only be transmitting or
497 receiving at any given moment. So we had to decide how to manage the
501 By design, the altimeter firmware listens for the radio link when
502 it's in "idle mode", which
503 allows us to use the radio link to configure the rocket, do things like
504 ejection tests, and extract data after a flight without having to
505 crack open the air-frame. However, when the board is in "flight
506 mode", the altimeter only
507 transmits and doesn't listen at all. That's because we want to put
508 ultimate priority on event detection and getting telemetry out of
510 the radio in case the rocket crashes and we aren't able to extract
514 We don't use a 'normal packet radio' mode like APRS because they're
515 just too inefficient. The GFSK modulation we use is FSK with the
516 base-band pulses passed through a
517 Gaussian filter before they go into the modulator to limit the
518 transmitted bandwidth. When combined with the hardware forward error
519 correction support in the cc1111 chip, this allows us to have a very
520 robust 38.4 kilobit data link with only 10 milliwatts of transmit
521 power, a whip antenna in the rocket, and a hand-held Yagi on the
522 ground. We've had flights to above 21k feet AGL with great reception,
523 and calculations suggest we should be good to well over 40k feet AGL
524 with a 5-element yagi on the ground. We hope to fly boards to higher
525 altitudes over time, and would of course appreciate customer feedback
526 on performance in higher altitude flights!
530 <title>Configurable Parameters</title>
532 Configuring an Altus Metrum altimeter for flight is very
533 simple. Even on our baro-only TeleMini board, the use of a Kalman
534 filter means there is no need to set a "mach delay". The few
535 configurable parameters can all be set using AltosUI over USB or
536 or radio link via TeleDongle.
539 <title>Radio Frequencies</title>
541 Altus Metrum boards support radio frequencies in the 70cm
542 band. By default, the configuration interface provides a
543 list of 10 "standard" frequencies in 100kHz channels starting at
544 434.550MHz. However, the firmware supports use of
545 any 50kHz multiple within the 70cm band. At any given
546 launch, we highly recommend coordinating when and by whom each
547 frequency will be used to avoid interference. And of course, both
548 altimeter and TeleDongle must be configured to the same
549 frequency to successfully communicate with each other.
553 <title>Apogee Delay</title>
555 Apogee delay is the number of seconds after the altimeter detects flight
556 apogee that the drogue charge should be fired. In most cases, this
557 should be left at the default of 0. However, if you are flying
558 redundant electronics such as for an L3 certification, you may wish
559 to set one of your altimeters to a positive delay so that both
560 primary and backup pyrotechnic charges do not fire simultaneously.
563 The Altus Metrum apogee detection algorithm fires exactly at
564 apogee. If you are also flying an altimeter like the
565 PerfectFlite MAWD, which only supports selecting 0 or 1
566 seconds of apogee delay, you may wish to set the MAWD to 0
567 seconds delay and set the TeleMetrum to fire your backup 2
568 or 3 seconds later to avoid any chance of both charges
569 firing simultaneously. We've flown several air-frames this
570 way quite happily, including Keith's successful L3 cert.
574 <title>Main Deployment Altitude</title>
576 By default, the altimeter will fire the main deployment charge at an
577 elevation of 250 meters (about 820 feet) above ground. We think this
578 is a good elevation for most air-frames, but feel free to change this
579 to suit. In particular, if you are flying two altimeters, you may
581 deployment elevation for the backup altimeter to be something lower
582 than the primary so that both pyrotechnic charges don't fire
588 <title>Calibration</title>
590 There are only two calibrations required for a TeleMetrum board, and
591 only one for TeleDongle and TeleMini.
594 <title>Radio Frequency</title>
596 The radio frequency is synthesized from a clock based on the 48 MHz
597 crystal on the board. The actual frequency of this oscillator must be
598 measured to generate a calibration constant. While our GFSK modulation
599 bandwidth is wide enough to allow boards to communicate even when
600 their oscillators are not on exactly the same frequency, performance
601 is best when they are closely matched.
602 Radio frequency calibration requires a calibrated frequency counter.
603 Fortunately, once set, the variation in frequency due to aging and
604 temperature changes is small enough that re-calibration by customers
605 should generally not be required.
608 When the radio calibration value is changed, the radio
609 frequency value is reset to the same value, so you'll need
610 to recompute and reset the radio frequency value using the
611 new radio calibration value.
615 <title>TeleMetrum Accelerometer</title>
617 The TeleMetrum accelerometer we use has its own 5 volt power supply and
618 the output must be passed through a resistive voltage divider to match
619 the input of our 3.3 volt ADC. This means that unlike the barometric
620 sensor, the output of the acceleration sensor is not ratio-metric to
621 the ADC converter, and calibration is required. We also support the
622 use of any of several accelerometers from a Freescale family that
623 includes at least +/- 40g, 50g, 100g, and 200g parts. Using gravity,
624 a simple 2-point calibration yields acceptable results capturing both
625 the different sensitivities and ranges of the different accelerometer
626 parts and any variation in power supply voltages or resistor values
627 in the divider network.
630 To calibrate the acceleration sensor, use the 'c a 0' command. You
631 will be prompted to orient the board vertically with the UHF antenna
632 up and press a key, then to orient the board vertically with the
633 UHF antenna down and press a key.
634 As with all 'c' sub-commands, follow this with a 'c w' to write the
635 change to the parameter block in the on-board DataFlash chip.
638 The +1g and -1g calibration points are included in each telemetry
639 frame and are part of the header extracted by ao-dumplog after flight.
640 Note that we always store and return raw ADC samples for each
641 sensor... nothing is permanently "lost" or "damaged" if the
645 In the unlikely event an accel cal that goes badly, it is possible
646 that TeleMetrum may always come up in 'pad mode' and as such not be
647 listening to either the USB or radio link. If that happens,
648 there is a special hook in the firmware to force the board back
649 in to 'idle mode' so you can re-do the cal. To use this hook, you
650 just need to ground the SPI clock pin at power-on. This pin is
651 available as pin 2 on the 8-pin companion connector, and pin 1 is
652 ground. So either carefully install a fine-gauge wire jumper
653 between the two pins closest to the index hole end of the 8-pin
654 connector, or plug in the programming cable to the 8-pin connector
655 and use a small screwdriver or similar to short the two pins closest
656 to the index post on the 4-pin end of the programming cable, and
657 power up the board. It should come up in 'idle mode' (two beeps).
665 <title>AltosUI</title>
667 The AltosUI program provides a graphical user interface for
668 interacting with the Altus Metrum product family, including
669 TeleMetrum, TeleMini and TeleDongle. AltosUI can monitor telemetry data,
670 configure TeleMetrum, TeleMini and TeleDongle devices and many other
671 tasks. The primary interface window provides a selection of
672 buttons, one for each major activity in the system. This manual
673 is split into chapters, each of which documents one of the tasks
674 provided from the top-level toolbar.
677 <title>Monitor Flight</title>
678 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
680 Selecting this item brings up a dialog box listing all of the
681 connected TeleDongle devices. When you choose one of these,
682 AltosUI will create a window to display telemetry data as
683 received by the selected TeleDongle device.
686 All telemetry data received are automatically recorded in
687 suitable log files. The name of the files includes the current
688 date and rocket serial and flight numbers.
691 The radio frequency being monitored by the TeleDongle device is
692 displayed at the top of the window. You can configure the
693 frequency by clicking on the frequency box and selecting the desired
694 frequency. AltosUI remembers the last frequency selected for each
695 TeleDongle and selects that automatically the next time you use
699 Below the TeleDongle frequency selector, the window contains a few
700 significant pieces of information about the altimeter providing
701 the telemetry data stream:
705 <para>The configured call-sign</para>
708 <para>The device serial number</para>
711 <para>The flight number. Each altimeter remembers how many
717 The rocket flight state. Each flight passes through several
718 states including Pad, Boost, Fast, Coast, Drogue, Main and
724 The Received Signal Strength Indicator value. This lets
725 you know how strong a signal TeleDongle is receiving. The
726 radio inside TeleDongle operates down to about -99dBm;
727 weaker signals may not be receivable. The packet link uses
728 error correction and detection techniques which prevent
729 incorrect data from being reported.
734 Finally, the largest portion of the window contains a set of
735 tabs, each of which contain some information about the rocket.
736 They're arranged in 'flight order' so that as the flight
737 progresses, the selected tab automatically switches to display
738 data relevant to the current state of the flight. You can select
739 other tabs at any time. The final 'table' tab contains all of
740 the telemetry data in one place.
743 <title>Launch Pad</title>
745 The 'Launch Pad' tab shows information used to decide when the
746 rocket is ready for flight. The first elements include red/green
747 indicators, if any of these is red, you'll want to evaluate
748 whether the rocket is ready to launch:
752 Battery Voltage. This indicates whether the Li-Po battery
753 powering the TeleMetrum has sufficient charge to last for
754 the duration of the flight. A value of more than
755 3.7V is required for a 'GO' status.
760 Apogee Igniter Voltage. This indicates whether the apogee
761 igniter has continuity. If the igniter has a low
762 resistance, then the voltage measured here will be close
763 to the Li-Po battery voltage. A value greater than 3.2V is
764 required for a 'GO' status.
769 Main Igniter Voltage. This indicates whether the main
770 igniter has continuity. If the igniter has a low
771 resistance, then the voltage measured here will be close
772 to the Li-Po battery voltage. A value greater than 3.2V is
773 required for a 'GO' status.
778 On-board Data Logging. This indicates whether there is
779 space remaining on-board to store flight data for the
780 upcoming flight. If you've downloaded data, but failed
781 to erase flights, there may not be any space
782 left. TeleMetrum can store multiple flights, depending
783 on the configured maximum flight log size. TeleMini
784 stores only a single flight, so it will need to be
785 downloaded and erased after each flight to capture
786 data. This only affects on-board flight logging; the
787 altimeter will still transmit telemetry and fire
788 ejection charges at the proper times.
793 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
794 currently able to compute position information. GPS requires
795 at least 4 satellites to compute an accurate position.
800 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
801 10 consecutive positions without losing lock. This ensures
802 that the GPS receiver has reliable reception from the
808 The Launchpad tab also shows the computed launch pad position
809 and altitude, averaging many reported positions to improve the
815 <title>Ascent</title>
817 This tab is shown during Boost, Fast and Coast
818 phases. The information displayed here helps monitor the
819 rocket as it heads towards apogee.
822 The height, speed and acceleration are shown along with the
823 maximum values for each of them. This allows you to quickly
824 answer the most commonly asked questions you'll hear during
828 The current latitude and longitude reported by the TeleMetrum GPS are
829 also shown. Note that under high acceleration, these values
830 may not get updated as the GPS receiver loses position
831 fix. Once the rocket starts coasting, the receiver should
832 start reporting position again.
835 Finally, the current igniter voltages are reported as in the
836 Launch Pad tab. This can help diagnose deployment failures
837 caused by wiring which comes loose under high acceleration.
841 <title>Descent</title>
843 Once the rocket has reached apogee and (we hope) activated the
844 apogee charge, attention switches to tracking the rocket on
845 the way back to the ground, and for dual-deploy flights,
846 waiting for the main charge to fire.
849 To monitor whether the apogee charge operated correctly, the
850 current descent rate is reported along with the current
851 height. Good descent rates generally range from 15-30m/s.
854 For TeleMetrum altimeters, you can locate the rocket in the sky
855 using the elevation and
856 bearing information to figure out where to look. Elevation is
857 in degrees above the horizon. Bearing is reported in degrees
858 relative to true north. Range can help figure out how big the
859 rocket will appear. Note that all of these values are relative
860 to the pad location. If the elevation is near 90°, the rocket
861 is over the pad, not over you.
864 Finally, the igniter voltages are reported in this tab as
865 well, both to monitor the main charge as well as to see what
866 the status of the apogee charge is.
870 <title>Landed</title>
872 Once the rocket is on the ground, attention switches to
873 recovery. While the radio signal is generally lost once the
874 rocket is on the ground, the last reported GPS position is
875 generally within a short distance of the actual landing location.
878 The last reported GPS position is reported both by
879 latitude and longitude as well as a bearing and distance from
880 the launch pad. The distance should give you a good idea of
881 whether you'll want to walk or hitch a ride. Take the reported
882 latitude and longitude and enter them into your hand-held GPS
883 unit and have that compute a track to the landing location.
886 Both TeleMini and TeleMetrum will continue to transmit RDF
887 tones after landing, allowing you to locate the rocket by
888 following the radio signal. You may need to get away from
889 the clutter of the flight line, or even get up on a hill (or
890 your neighbor's RV) to receive the RDF signal.
893 The maximum height, speed and acceleration reported
894 during the flight are displayed for your admiring observers.
897 To get more detailed information about the flight, you can
898 click on the 'Graph Flight' button which will bring up a
899 graph window for the current flight.
903 <title>Site Map</title>
905 When the TeleMetrum gets a GPS fix, the Site Map tab will map
906 the rocket's position to make it easier for you to locate the
907 rocket, both while it is in the air, and when it has landed. The
908 rocket's state is indicated by color: white for pad, red for
909 boost, pink for fast, yellow for coast, light blue for drogue,
910 dark blue for main, and black for landed.
913 The map's scale is approximately 3m (10ft) per pixel. The map
914 can be dragged using the left mouse button. The map will attempt
915 to keep the rocket roughly centered while data is being received.
918 Images are fetched automatically via the Google Maps Static API,
919 and are cached for reuse. If map images cannot be downloaded,
920 the rocket's path will be traced on a dark gray background
924 You can pre-load images for your favorite launch sites
925 before you leave home; check out the 'Preload Maps' section below.
930 <title>Save Flight Data</title>
932 The altimeter records flight data to its internal flash memory.
933 The TeleMetrum data is recorded at a much higher rate than the telemetry
934 system can handle, and is not subject to radio drop-outs. As
935 such, it provides a more complete and precise record of the
936 flight. The 'Save Flight Data' button allows you to read the
937 flash memory and write it to disk. As TeleMini has only a barometer, it
938 records data at the same rate as the telemetry signal, but there will be
939 no data lost due to telemetry drop-outs.
942 Clicking on the 'Save Flight Data' button brings up a list of
943 connected TeleMetrum and TeleDongle devices. If you select a
944 TeleMetrum device, the flight data will be downloaded from that
945 device directly. If you select a TeleDongle device, flight data
946 will be downloaded from a TeleMetrum or TeleMini device connected via the
947 packet command link to the specified TeleDongle. See the chapter
948 on Packet Command Mode for more information about this.
951 After the device has been selected, a dialog showing the
952 flight data saved in the device will be shown allowing you to
953 select which flights to download and which to delete. With
954 version 0.9 or newer firmware, you must erase flights in order
955 for the space they consume to be reused by another
956 flight. This prevents you from accidentally losing flight data
957 if you neglect to download data before flying again. Note that
958 if there is no more space available in the device, then no
959 data will be recorded for a flight.
962 The file name for each flight log is computed automatically
963 from the recorded flight date, altimeter serial number and
964 flight number information.
968 <title>Replay Flight</title>
970 Select this button and you are prompted to select a flight
971 record file, either a .telem file recording telemetry data or a
972 .eeprom file containing flight data saved from the altimeter
976 Once a flight record is selected, the flight monitor interface
977 is displayed and the flight is re-enacted in real time. Check
978 the Monitor Flight chapter above to learn how this window operates.
982 <title>Graph Data</title>
984 Select this button and you are prompted to select a flight
985 record file, either a .telem file recording telemetry data or a
986 .eeprom file containing flight data saved from
990 Once a flight record is selected, a window with two tabs is
991 opened. The first tab contains a graph with acceleration
992 (blue), velocity (green) and altitude (red) of the flight are
993 plotted and displayed, measured in metric units. The
994 apogee(yellow) and main(magenta) igniter voltages are also
995 displayed; high voltages indicate continuity, low voltages
996 indicate open circuits. The second tab contains some basic
1000 The graph can be zoomed into a particular area by clicking and
1001 dragging down and to the right. Once zoomed, the graph can be
1002 reset by clicking and dragging up and to the left. Holding down
1003 control and clicking and dragging allows the graph to be panned.
1004 The right mouse button causes a pop-up menu to be displayed, giving
1005 you the option save or print the plot.
1008 Note that telemetry files will generally produce poor graphs
1009 due to the lower sampling rate and missed telemetry packets.
1010 Use saved flight data for graphing where possible.
1014 <title>Export Data</title>
1016 This tool takes the raw data files and makes them available for
1017 external analysis. When you select this button, you are prompted to select a flight
1018 data file (either .eeprom or .telem will do, remember that
1019 .eeprom files contain higher resolution and more continuous
1020 data). Next, a second dialog appears which is used to select
1021 where to write the resulting file. It has a selector to choose
1022 between CSV and KML file formats.
1025 <title>Comma Separated Value Format</title>
1027 This is a text file containing the data in a form suitable for
1028 import into a spreadsheet or other external data analysis
1029 tool. The first few lines of the file contain the version and
1030 configuration information from the altimeter, then
1031 there is a single header line which labels all of the
1032 fields. All of these lines start with a '#' character which
1033 most tools can be configured to skip over.
1036 The remaining lines of the file contain the data, with each
1037 field separated by a comma and at least one space. All of
1038 the sensor values are converted to standard units, with the
1039 barometric data reported in both pressure, altitude and
1040 height above pad units.
1044 <title>Keyhole Markup Language (for Google Earth)</title>
1046 This is the format used by
1047 Googleearth to provide an overlay within that
1048 application. With this, you can use Googleearth to see the
1049 whole flight path in 3D.
1054 <title>Configure Altimeter</title>
1056 Select this button and then select either a TeleMetrum or
1057 TeleDongle Device from the list provided. Selecting a TeleDongle
1058 device will use Packet Command Mode to configure a remote
1059 altimeter. Learn how to use this in the Packet Command
1063 The first few lines of the dialog provide information about the
1064 connected device, including the product name,
1065 software version and hardware serial number. Below that are the
1066 individual configuration entries.
1069 At the bottom of the dialog, there are four buttons:
1074 Save. This writes any changes to the
1075 configuration parameter block in flash memory. If you don't
1076 press this button, any changes you make will be lost.
1081 Reset. This resets the dialog to the most recently saved values,
1082 erasing any changes you have made.
1087 Reboot. This reboots the device. Use this to
1088 switch from idle to pad mode by rebooting once the rocket is
1089 oriented for flight.
1094 Close. This closes the dialog. Any unsaved changes will be
1100 The rest of the dialog contains the parameters to be configured.
1103 <title>Main Deploy Altitude</title>
1105 This sets the altitude (above the recorded pad altitude) at
1106 which the 'main' igniter will fire. The drop-down menu shows
1107 some common values, but you can edit the text directly and
1108 choose whatever you like. If the apogee charge fires below
1109 this altitude, then the main charge will fire two seconds
1110 after the apogee charge fires.
1114 <title>Apogee Delay</title>
1116 When flying redundant electronics, it's often important to
1117 ensure that multiple apogee charges don't fire at precisely
1118 the same time as that can over pressurize the apogee deployment
1119 bay and cause a structural failure of the air-frame. The Apogee
1120 Delay parameter tells the flight computer to fire the apogee
1121 charge a certain number of seconds after apogee has been
1126 <title>Radio Frequency</title>
1128 This configures which of the configured frequencies to use for both
1129 telemetry and packet command mode. Note that if you set this
1130 value via packet command mode, you will have to reconfigure
1131 the TeleDongle frequency before you will be able to use packet
1136 <title>Radio Calibration</title>
1138 The radios in every Altus Metrum device are calibrated at the
1139 factory to ensure that they transmit and receive on the
1140 specified frequency. You can adjust that
1141 calibration by changing this value. To change the TeleDongle's
1142 calibration, you must reprogram the unit completely.
1146 <title>Callsign</title>
1148 This sets the call sign included in each telemetry packet. Set this
1149 as needed to conform to your local radio regulations.
1153 <title>Maximum Flight Log Size</title>
1155 This sets the space (in kilobytes) allocated for each flight
1156 log. The available space will be divided into chunks of this
1157 size. A smaller value will allow more flights to be stored,
1158 a larger value will record data from longer flights.
1161 During ascent, TeleMetrum records barometer and
1162 accelerometer values 100 times per second, other analog
1163 information (voltages and temperature) 6 times per second
1164 and GPS data once per second. During descent, the non-GPS
1165 data is recorded 1/10th as often. Each barometer +
1166 accelerometer record takes 8 bytes.
1169 The default, 192kB, will store over 200 seconds of data at
1170 the ascent rate, or over 2000 seconds of data at the descent
1171 rate. That's plenty for most flights. This leaves enough
1172 storage for five flights in a 1MB system, or 10 flights in a
1176 The configuration block takes the last available block of
1177 memory, on v1.0 boards that's just 256 bytes. However, the
1178 flash part on the v1.1 boards uses 64kB for each block.
1181 TeleMini has 5kB of on-board storage, which is plenty for a
1182 single flight. Make sure you download and delete the data
1183 before a subsequent flight or it will not log any data.
1187 <title>Ignite Mode</title>
1189 TeleMetrum and TeleMini provide two igniter channels as they
1190 were originally designed as dual-deploy flight
1191 computers. This configuration parameter allows the two
1192 channels to be used in different configurations.
1197 Dual Deploy. This is the usual mode of operation; the
1198 'apogee' channel is fired at apogee and the 'main'
1199 channel at the height above ground specified by the
1200 'Main Deploy Altitude' during descent.
1205 Redundant Apogee. This fires both channels at
1206 apogee, the 'apogee' channel first followed after a two second
1207 delay by the 'main' channel.
1212 Redundant Main. This fires both channels at the
1213 height above ground specified by the Main Deploy
1214 Altitude setting during descent. The 'apogee'
1215 channel is fired first, followed after a two second
1216 delay by the 'main' channel.
1222 <title>Pad Orientation</title>
1224 Because it includes an accelerometer, TeleMetrum is
1225 sensitive to the orientation of the board. By default, it
1226 expects the antenna end to point forward. This parameter
1227 allows that default to be changed, permitting the board to
1228 be mounted with the antenna pointing aft instead.
1233 Antenna Up. In this mode, the antenna end of the
1234 TeleMetrum board must point forward, in line with the
1235 expected flight path.
1240 Antenna Down. In this mode, the antenna end of the
1241 TeleMetrum board must point aft, in line with the
1242 expected flight path.
1249 <title>Configure AltosUI</title>
1251 This button presents a dialog so that you can configure the AltosUI global settings.
1254 <title>Voice Settings</title>
1256 AltosUI provides voice announcements during flight so that you
1257 can keep your eyes on the sky and still get information about
1258 the current flight status. However, sometimes you don't want
1263 <para>Enable—turns all voice announcements on and off</para>
1267 Test Voice—Plays a short message allowing you to verify
1268 that the audio system is working and the volume settings
1275 <title>Log Directory</title>
1277 AltosUI logs all telemetry data and saves all TeleMetrum flash
1278 data to this directory. This directory is also used as the
1279 staring point when selecting data files for display or export.
1282 Click on the directory name to bring up a directory choosing
1283 dialog, select a new directory and click 'Select Directory' to
1284 change where AltosUI reads and writes data files.
1288 <title>Callsign</title>
1290 This value is used in command packet mode and is transmitted
1291 in each packet sent from TeleDongle and received from
1292 TeleMetrum. It is not used in telemetry mode as that transmits
1293 packets only from TeleMetrum to TeleDongle. Configure this
1294 with the AltosUI operators call sign as needed to comply with
1295 your local radio regulations.
1299 <title>Font Size</title>
1301 Selects the set of fonts used in the flight monitor
1302 window. Choose between the small, medium and large sets.
1306 <title>Serial Debug</title>
1308 This causes all communication with a connected device to be
1309 dumped to the console from which AltosUI was started. If
1310 you've started it from an icon or menu entry, the output
1311 will simply be discarded. This mode can be useful to debug
1312 various serial communication issues.
1316 <title>Manage Frequencies</title>
1318 This brings up a dialog where you can configure the set of
1319 frequencies shown in the various frequency menus. You can
1320 add as many as you like, or even reconfigure the default
1321 set. Changing this list does not affect the frequency
1322 settings of any devices, it only changes the set of
1323 frequencies shown in the menus.
1328 <title>Flash Image</title>
1330 This reprograms any Altus Metrum device by using a TeleMetrum
1331 or TeleDongle as a programming dongle. Please read the
1332 directions for flashing devices in the Updating Device
1333 Firmware chapter below.
1336 Once you have the programmer and target devices connected,
1337 push the 'Flash Image' button. That will present a dialog box
1338 listing all of the connected devices. Carefully select the
1339 programmer device, not the device to be programmed.
1342 Next, select the image to flash to the device. These are named
1343 with the product name and firmware version. The file selector
1344 will start in the directory containing the firmware included
1345 with the AltosUI package. Navigate to the directory containing
1346 the desired firmware if it isn't there.
1349 Next, a small dialog containing the device serial number and
1350 RF calibration values should appear. If these values are
1351 incorrect (possibly due to a corrupted image in the device),
1352 enter the correct values here.
1355 Finally, a dialog containing a progress bar will follow the
1356 programming process.
1359 When programming is complete, the target device will
1360 reboot. Note that if the target device is connected via USB, you
1361 will have to unplug it and then plug it back in for the USB
1362 connection to reset so that you can communicate with the device
1367 <title>Fire Igniter</title>
1369 This activates the igniter circuits in TeleMetrum to help test
1370 recovery systems deployment. Because this command can operate
1371 over the Packet Command Link, you can prepare the rocket as
1372 for flight and then test the recovery system without needing
1373 to snake wires inside the air-frame.
1376 Selecting the 'Fire Igniter' button brings up the usual device
1377 selection dialog. Pick the desired TeleDongle or TeleMetrum
1378 device. This brings up another window which shows the current
1379 continuity test status for both apogee and main charges.
1382 Next, select the desired igniter to fire. This will enable the
1386 Select the 'Arm' button. This enables the 'Fire' button. The
1387 word 'Arm' is replaced by a countdown timer indicating that
1388 you have 10 seconds to press the 'Fire' button or the system
1389 will deactivate, at which point you start over again at
1390 selecting the desired igniter.
1394 <title>Scan Channels</title>
1396 This listens for telemetry packets on all of the configured
1397 frequencies, displaying information about each device it
1398 receives a packet from. You can select which of the three
1399 telemetry formats should be tried; by default, it only listens
1400 for the standard telemetry packets used in v1.0 and later
1405 <title>Load Maps</title>
1407 Before heading out to a new launch site, you can use this to
1408 load satellite images in case you don't have internet
1409 connectivity at the site. This loads a fairly large area
1410 around the launch site, which should cover any flight you're likely to make.
1413 There's a drop-down menu of launch sites we know about; if
1414 your favorites aren't there, please let us know the lat/lon
1415 and name of the site. The contents of this list are actually
1416 downloaded at run-time, so as new sites are sent in, they'll
1417 get automatically added to this list.
1420 If the launch site isn't in the list, you can manually enter the lat/lon values
1423 Clicking the 'Load Map' button will fetch images from Google
1424 Maps; note that Google limits how many images you can fetch at
1425 once, so if you load more than one launch site, you may get
1426 some gray areas in the map which indicate that Google is tired
1427 of sending data to you. Try again later.
1431 <title>Monitor Idle</title>
1433 This brings up a dialog similar to the Monitor Flight UI,
1434 except it works with the altimeter in "idle" mode by sending
1435 query commands to discover the current state rather than
1436 listening for telemetry packets.
1441 <title>Using Altus Metrum Products</title>
1443 <title>Being Legal</title>
1445 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
1446 other authorization to legally operate the radio transmitters that are part
1451 <title>In the Rocket</title>
1453 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
1454 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
1455 a Li-Po rechargeable battery. An 860mAh battery weighs less than a 9V
1456 alkaline battery, and will run a TeleMetrum for hours.
1457 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
1458 a few hours, or a TeleMini for much (much) longer.
1461 By default, we ship the altimeters with a simple wire antenna. If your
1462 electronics bay or the air-frame it resides within is made of carbon fiber,
1463 which is opaque to RF signals, you may choose to have an SMA connector
1464 installed so that you can run a coaxial cable to an antenna mounted
1465 elsewhere in the rocket.
1469 <title>On the Ground</title>
1471 To receive the data stream from the rocket, you need an antenna and short
1472 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. The
1473 TeleDongle in turn plugs directly into the USB port on a notebook
1474 computer. Because TeleDongle looks like a simple serial port, your computer
1475 does not require special device drivers... just plug it in.
1478 The GUI tool, AltosUI, is written in Java and runs across
1479 Linux, Mac OS and Windows. There's also a suite of C tools
1480 for Linux which can perform most of the same tasks.
1483 After the flight, you can use the radio link to extract the more detailed data
1484 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
1485 TeleMetrum board directly. Pulling out the data without having to open up
1486 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
1487 battery, so you'll want one of those anyway... the same cable used by lots
1488 of digital cameras and other modern electronic stuff will work fine.
1491 If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
1492 receiver, so that you can put in a way-point for the last reported rocket
1493 position before touch-down. This makes looking for your rocket a lot like
1494 Geo-Caching... just go to the way-point and look around starting from there.
1497 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
1498 can use that with your antenna to direction-find the rocket on the ground
1499 the same way you can use a Walston or Beeline tracker. This can be handy
1500 if the rocket is hiding in sage brush or a tree, or if the last GPS position
1501 doesn't get you close enough because the rocket dropped into a canyon, or
1502 the wind is blowing it across a dry lake bed, or something like that... Keith
1503 and Bdale both currently own and use the Yaesu VX-7R at launches.
1506 So, to recap, on the ground the hardware you'll need includes:
1507 <orderedlist inheritnum='inherit' numeration='arabic'>
1509 an antenna and feed-line
1518 optionally, a hand-held GPS receiver
1521 optionally, an HT or receiver covering 435 MHz
1526 The best hand-held commercial directional antennas we've found for radio
1527 direction finding rockets are from
1528 <ulink url="http://www.arrowantennas.com/" >
1531 The 440-3 and 440-5 are both good choices for finding a
1532 TeleMetrum- or TeleMini- equipped rocket when used with a suitable 70cm HT.
1536 <title>Data Analysis</title>
1538 Our software makes it easy to log the data from each flight, both the
1539 telemetry received during the flight itself, and the more
1540 complete data log recorded in the flash memory on the altimeter
1541 board. Once this data is on your computer, our post-flight tools make it
1542 easy to quickly get to the numbers everyone wants, like apogee altitude,
1543 max acceleration, and max velocity. You can also generate and view a
1544 standard set of plots showing the altitude, acceleration, and
1545 velocity of the rocket during flight. And you can even export a TeleMetrum data file
1546 usable with Google Maps and Google Earth for visualizing the flight path
1547 in two or three dimensions!
1550 Our ultimate goal is to emit a set of files for each flight that can be
1551 published as a web page per flight, or just viewed on your local disk with
1556 <title>Future Plans</title>
1558 In the future, we intend to offer "companion boards" for the rocket that will
1559 plug in to TeleMetrum to collect additional data, provide more pyro channels,
1560 and so forth. A reference design for a companion board will be documented
1561 soon, and will be compatible with open source Arduino programming tools.
1564 We are also working on the design of a hand-held ground terminal that will
1565 allow monitoring the rocket's status, collecting data during flight, and
1566 logging data after flight without the need for a notebook computer on the
1567 flight line. Particularly since it is so difficult to read most notebook
1568 screens in direct sunlight, we think this will be a great thing to have.
1571 Because all of our work is open, both the hardware designs and the software,
1572 if you have some great idea for an addition to the current Altus Metrum family,
1573 feel free to dive in and help! Or let us know what you'd like to see that
1574 we aren't already working on, and maybe we'll get excited about it too...
1579 <title>Altimeter Installation Recommendations</title>
1581 Building high-power rockets that fly safely is hard enough. Mix
1582 in some sophisticated electronics and a bunch of radio energy
1583 and oftentimes you find few perfect solutions. This chapter
1584 contains some suggestions about how to install Altus Metrum
1585 products into the rocket air-frame, including how to safely and
1586 reliably mix a variety of electronics into the same air-frame.
1589 <title>Mounting the Altimeter</title>
1591 The first consideration is to ensure that the altimeter is
1592 securely fastened to the air-frame. For TeleMetrum, we use
1593 nylon standoffs and nylon screws; they're good to at least 50G
1594 and cannot cause any electrical issues on the board. For
1595 TeleMini, we usually cut small pieces of 1/16" balsa to fit
1596 under the screw holes, and then take 2x56 nylon screws and
1597 screw them through the TeleMini mounting holes, through the
1598 balsa and into the underlying material.
1600 <orderedlist inheritnum='inherit' numeration='arabic'>
1602 Make sure TeleMetrum is aligned precisely along the axis of
1603 acceleration so that the accelerometer can accurately
1604 capture data during the flight.
1607 Watch for any metal touching components on the
1608 board. Shorting out connections on the bottom of the board
1609 can cause the altimeter to fail during flight.
1614 <title>Dealing with the Antenna</title>
1616 The antenna supplied is just a piece of solid, insulated,
1617 wire. If it gets damaged or broken, it can be easily
1618 replaced. It should be kept straight and not cut; bending or
1619 cutting it will change the resonant frequency and/or
1620 impedance, making it a less efficient radiator and thus
1621 reducing the range of the telemetry signal.
1624 Keeping metal away from the antenna will provide better range
1625 and a more even radiation pattern. In most rockets, it's not
1626 entirely possible to isolate the antenna from metal
1627 components; there are often bolts, all-thread and wires from other
1628 electronics to contend with. Just be aware that the more stuff
1629 like this around the antenna, the lower the range.
1632 Make sure the antenna is not inside a tube made or covered
1633 with conducting material. Carbon fiber is the most common
1634 culprit here -- CF is a good conductor and will effectively
1635 shield the antenna, dramatically reducing signal strength and
1636 range. Metallic flake paint is another effective shielding
1637 material which is to be avoided around any antennas.
1640 If the ebay is large enough, it can be convenient to simply
1641 mount the altimeter at one end and stretch the antenna out
1642 inside. Taping the antenna to the sled can keep it straight
1643 under acceleration. If there are metal rods, keep the
1644 antenna as far away as possible.
1647 For a shorter ebay, it's quite practical to have the antenna
1648 run through a bulkhead and into an adjacent bay. Drill a small
1649 hole in the bulkhead, pass the antenna wire through it and
1650 then seal it up with glue or clay. We've also used acrylic
1651 tubing to create a cavity for the antenna wire. This works a
1652 bit better in that the antenna is known to stay straight and
1653 not get folded by recovery components in the bay. Angle the
1654 tubing towards the side wall of the rocket and it ends up
1655 consuming very little space.
1658 If you need to place the antenna at a distance from the
1659 altimeter, you can replace the antenna with an edge-mounted
1660 SMA connector, and then run 50Ω coax from the board to the
1661 antenna. Building a remote antenna is beyond the scope of this
1666 <title>Preserving GPS Reception</title>
1668 The GPS antenna and receiver in TeleMetrum are highly
1669 sensitive and normally have no trouble tracking enough
1670 satellites to provide accurate position information for
1671 recovering the rocket. However, there are many ways to
1672 attenuate the GPS signal.
1673 <orderedlist inheritnum='inherit' numeration='arabic'>
1675 Conductive tubing or coatings. Carbon fiber and metal
1676 tubing, or metallic paint will all dramatically attenuate the
1677 GPS signal. We've never heard of anyone successfully
1678 receiving GPS from inside these materials.
1681 Metal components near the GPS patch antenna. These will
1682 de-tune the patch antenna, changing the resonant frequency
1683 away from the L1 carrier and reduce the effectiveness of the
1684 antenna. You can place as much stuff as you like beneath the
1685 antenna as that's covered with a ground plane. But, keep
1686 wires and metal out from above the patch antenna.
1692 <title>Radio Frequency Interference</title>
1694 Any altimeter will generate RFI; the digital circuits use
1695 high-frequency clocks that spray radio interference across a
1696 wide band. Altusmetrum altimeters generate intentional radio
1697 signals as well, increasing the amount of RF energy around the board.
1700 Rocketry altimeters also use precise sensors measuring air
1701 pressure and acceleration. Tiny changes in voltage can cause
1702 these sensor readings to vary by a huge amount. When the
1703 sensors start mis-reporting data, the altimeter can either
1704 fire the igniters at the wrong time, or not fire them at all.
1707 Voltages are induced when radio frequency energy is
1708 transmitted from one circuit to another. Here are things that
1709 increase the induced voltage and current:
1713 Keep wires from different circuits apart. Moving circuits
1714 further apart will reduce RFI.
1717 Avoid parallel wires from different circuits. The longer two
1718 wires run parallel to one another, the larger the amount of
1719 transferred energy. Cross wires at right angles to reduce
1723 Twist wires from the same circuits. Two wires the same
1724 distance from the transmitter will get the same amount of
1725 induced energy which will then cancel out. Any time you have
1726 a wire pair running together, twist the pair together to
1727 even out distances and reduce RFI. For altimeters, this
1728 includes battery leads, switch hookups and igniter
1732 Avoid resonant lengths. Know what frequencies are present
1733 in the environment and avoid having wire lengths near a
1734 natural resonant length. Altusmetrum products transmit on the
1735 70cm amateur band, so you should avoid lengths that are a
1736 simple ratio of that length; essentially any multiple of 1/4
1737 of the wavelength (17.5cm).
1742 <title>The Barometric Sensor</title>
1744 Altusmetrum altimeters measure altitude with a barometric
1745 sensor, essentially measuring the amount of air above the
1746 rocket to figure out how high it is. A large number of
1747 measurements are taken as the altimeter initializes itself to
1748 figure out the pad altitude. Subsequent measurements are then
1749 used to compute the height above the pad.
1752 To accurately measure atmospheric pressure, the ebay
1753 containing the altimeter must be vented outside the
1754 air-frame. The vent must be placed in a region of linear
1755 airflow, smooth and not in an area of increasing or decreasing
1759 The barometric sensor in the altimeter is quite sensitive to
1760 chemical damage from the products of APCP or BP combustion, so
1761 make sure the ebay is carefully sealed from any compartment
1762 which contains ejection charges or motors.
1766 <title>Ground Testing</title>
1768 The most important aspect of any installation is careful
1769 ground testing. Bringing an air-frame up to the LCO table which
1770 hasn't been ground tested can lead to delays or ejection
1771 charges firing on the pad, or, even worse, a recovery system
1775 Do a 'full systems' test that includes wiring up all igniters
1776 without any BP and turning on all of the electronics in flight
1777 mode. This will catch any mistakes in wiring and any residual
1778 RFI issues that might accidentally fire igniters at the wrong
1779 time. Let the air-frame sit for several minutes, checking for
1780 adequate telemetry signal strength and GPS lock.
1783 Ground test the ejection charges. Prepare the rocket for
1784 flight, loading ejection charges and igniters. Completely
1785 assemble the air-frame and then use the 'Fire Igniters'
1786 interface through a TeleDongle to command each charge to
1787 fire. Make sure the charge is sufficient to robustly separate
1788 the air-frame and deploy the recovery system.
1793 <title>Updating Device Firmware</title>
1795 The big conceptual thing to realize is that you have to use a
1796 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
1797 and a TeleMetrum or other TeleDongle to program the TeleDongle
1798 Due to limited memory resources in the cc1111, we don't support
1799 programming directly over USB.
1802 You may wish to begin by ensuring you have current firmware images.
1803 These are distributed as part of the AltOS software bundle that
1804 also includes the AltosUI ground station program. Newer ground
1805 station versions typically work fine with older firmware versions,
1806 so you don't need to update your devices just to try out new
1807 software features. You can always download the most recent
1808 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
1811 We recommend updating the altimeter first, before updating TeleDongle.
1814 <title>Updating TeleMetrum Firmware</title>
1815 <orderedlist inheritnum='inherit' numeration='arabic'>
1817 Find the 'programming cable' that you got as part of the starter
1818 kit, that has a red 8-pin MicroMaTch connector on one end and a
1819 red 4-pin MicroMaTch connector on the other end.
1822 Take the 2 screws out of the TeleDongle case to get access
1823 to the circuit board.
1826 Plug the 8-pin end of the programming cable to the
1827 matching connector on the TeleDongle, and the 4-pin end to the
1828 matching connector on the TeleMetrum.
1829 Note that each MicroMaTch connector has an alignment pin that
1830 goes through a hole in the PC board when you have the cable
1834 Attach a battery to the TeleMetrum board.
1837 Plug the TeleDongle into your computer's USB port, and power
1841 Run AltosUI, and select 'Flash Image' from the File menu.
1844 Pick the TeleDongle device from the list, identifying it as the
1848 Select the image you want put on the TeleMetrum, which should have a
1849 name in the form telemetrum-v1.1-1.0.0.ihx. It should be visible
1850 in the default directory, if not you may have to poke around
1851 your system to find it.
1854 Make sure the configuration parameters are reasonable
1855 looking. If the serial number and/or RF configuration
1856 values aren't right, you'll need to change them.
1859 Hit the 'OK' button and the software should proceed to flash
1860 the TeleMetrum with new firmware, showing a progress bar.
1863 Confirm that the TeleMetrum board seems to have updated OK, which you
1864 can do by plugging in to it over USB and using a terminal program
1865 to connect to the board and issue the 'v' command to check
1869 If something goes wrong, give it another try.
1874 <title>Updating TeleMini Firmware</title>
1875 <orderedlist inheritnum='inherit' numeration='arabic'>
1877 You'll need a special 'programming cable' to reprogram the
1878 TeleMini. It's available on the Altus Metrum web store, or
1879 you can make your own using an 8-pin MicroMaTch connector on
1880 one end and a set of four pins on the other.
1883 Take the 2 screws out of the TeleDongle case to get access
1884 to the circuit board.
1887 Plug the 8-pin end of the programming cable to the matching
1888 connector on the TeleDongle, and the 4-pins into the holes
1889 in the TeleMini circuit board. Note that the MicroMaTch
1890 connector has an alignment pin that goes through a hole in
1891 the PC board when you have the cable oriented correctly, and
1892 that pin 1 on the TeleMini board is marked with a square pad
1893 while the other pins have round pads.
1896 Attach a battery to the TeleMini board.
1899 Plug the TeleDongle into your computer's USB port, and power
1903 Run AltosUI, and select 'Flash Image' from the File menu.
1906 Pick the TeleDongle device from the list, identifying it as the
1910 Select the image you want put on the TeleMini, which should have a
1911 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
1912 in the default directory, if not you may have to poke around
1913 your system to find it.
1916 Make sure the configuration parameters are reasonable
1917 looking. If the serial number and/or RF configuration
1918 values aren't right, you'll need to change them.
1921 Hit the 'OK' button and the software should proceed to flash
1922 the TeleMini with new firmware, showing a progress bar.
1925 Confirm that the TeleMini board seems to have updated OK, which you
1926 can do by configuring it over the radio link through the TeleDongle, or
1927 letting it come up in "flight" mode and listening for telemetry.
1930 If something goes wrong, give it another try.
1935 <title>Updating TeleDongle Firmware</title>
1937 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
1938 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
1940 <orderedlist inheritnum='inherit' numeration='arabic'>
1942 Find the 'programming cable' that you got as part of the starter
1943 kit, that has a red 8-pin MicroMaTch connector on one end and a
1944 red 4-pin MicroMaTch connector on the other end.
1947 Find the USB cable that you got as part of the starter kit, and
1948 plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
1951 Take the 2 screws out of the TeleDongle case to get access
1952 to the circuit board.
1955 Plug the 8-pin end of the programming cable to the
1956 matching connector on the programmer, and the 4-pin end to the
1957 matching connector on the TeleDongle.
1958 Note that each MicroMaTch connector has an alignment pin that
1959 goes through a hole in the PC board when you have the cable
1963 Attach a battery to the TeleMetrum board if you're using one.
1966 Plug both the programmer and the TeleDongle into your computer's USB
1967 ports, and power up the programmer.
1970 Run AltosUI, and select 'Flash Image' from the File menu.
1973 Pick the programmer device from the list, identifying it as the
1977 Select the image you want put on the TeleDongle, which should have a
1978 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
1979 in the default directory, if not you may have to poke around
1980 your system to find it.
1983 Make sure the configuration parameters are reasonable
1984 looking. If the serial number and/or RF configuration
1985 values aren't right, you'll need to change them. The TeleDongle
1986 serial number is on the "bottom" of the circuit board, and can
1987 usually be read through the translucent blue plastic case without
1988 needing to remove the board from the case.
1991 Hit the 'OK' button and the software should proceed to flash
1992 the TeleDongle with new firmware, showing a progress bar.
1995 Confirm that the TeleDongle board seems to have updated OK, which you
1996 can do by plugging in to it over USB and using a terminal program
1997 to connect to the board and issue the 'v' command to check
1998 the version, etc. Once you're happy, remove the programming cable
1999 and put the cover back on the TeleDongle.
2002 If something goes wrong, give it another try.
2006 Be careful removing the programming cable from the locking 8-pin
2007 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
2008 screwdriver or knife blade to gently pry the locking ears out
2009 slightly to extract the connector. We used a locking connector on
2010 TeleMetrum to help ensure that the cabling to companion boards
2011 used in a rocket don't ever come loose accidentally in flight.
2016 <title>Hardware Specifications</title>
2018 <title>TeleMetrum Specifications</title>
2022 Recording altimeter for model rocketry.
2027 Supports dual deployment (can fire 2 ejection charges).
2032 70cm ham-band transceiver for telemetry down-link.
2037 Barometric pressure sensor good to 45k feet MSL.
2042 1-axis high-g accelerometer for motor characterization, capable of
2043 +/- 50g using default part.
2048 On-board, integrated GPS receiver with 5Hz update rate capability.
2053 On-board 1 megabyte non-volatile memory for flight data storage.
2058 USB interface for battery charging, configuration, and data recovery.
2063 Fully integrated support for Li-Po rechargeable batteries.
2068 Uses Li-Po to fire e-matches, can be modified to support
2069 optional separate pyro battery if needed.
2074 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
2080 <title>TeleMini Specifications</title>
2084 Recording altimeter for model rocketry.
2089 Supports dual deployment (can fire 2 ejection charges).
2094 70cm ham-band transceiver for telemetry down-link.
2099 Barometric pressure sensor good to 45k feet MSL.
2104 On-board 5 kilobyte non-volatile memory for flight data storage.
2109 RF interface for battery charging, configuration, and data recovery.
2114 Support for Li-Po rechargeable batteries, using an external charger.
2119 Uses Li-Po to fire e-matches, can be modified to support
2120 optional separate pyro battery if needed.
2125 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
2134 TeleMetrum seems to shut off when disconnected from the
2135 computer. Make sure the battery is adequately charged. Remember the
2136 unit will pull more power than the USB port can deliver before the
2137 GPS enters "locked" mode. The battery charges best when TeleMetrum
2141 It's impossible to stop the TeleDongle when it's in "p" mode, I have
2142 to unplug the USB cable? Make sure you have tried to "escape out" of
2143 this mode. If this doesn't work the reboot procedure for the
2144 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
2145 outgoing buffer IF your "escape out" ('~~') does not work.
2146 At this point using either 'ao-view' (or possibly
2147 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
2151 The amber LED (on the TeleMetrum) lights up when both
2152 battery and USB are connected. Does this mean it's charging?
2153 Yes, the yellow LED indicates the charging at the 'regular' rate.
2154 If the led is out but the unit is still plugged into a USB port,
2155 then the battery is being charged at a 'trickle' rate.
2158 There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
2159 That's the "pad" mode. Weak batteries might be the problem.
2160 It is also possible that the TeleMetrum is horizontal and the output
2161 is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
2162 it received a command packet which would have left it in "pad" mode.
2165 How do I save flight data?
2166 Live telemetry is written to file(s) whenever AltosUI is connected
2167 to the TeleDongle. The file area defaults to ~/TeleMetrum
2168 but is easily changed using the menus in AltosUI. The files that
2169 are written end in '.telem'. The after-flight
2170 data-dumped files will end in .eeprom and represent continuous data
2171 unlike the .telem files that are subject to losses
2172 along the RF data path.
2173 See the above instructions on what and how to save the eeprom stored
2174 data after physically retrieving your altimeter. Make sure to save
2175 the on-board data after each flight; while the TeleMetrum can store
2176 multiple flights, you never know when you'll lose the altimeter...
2180 <title>Notes for Older Software</title>
2183 Before AltosUI was written, using Altus Metrum devices required
2184 some finesse with the Linux command line. There was a limited
2185 GUI tool, ao-view, which provided functionality similar to the
2186 Monitor Flight window in AltosUI, but everything else was a
2187 fairly 80's experience. This appendix includes documentation for
2188 using that software.
2192 Both TeleMetrum and TeleDongle can be directly communicated
2193 with using USB ports. The first thing you should try after getting
2194 both units plugged into to your computer's USB port(s) is to run
2195 'ao-list' from a terminal-window to see what port-device-name each
2196 device has been assigned by the operating system.
2197 You will need this information to access the devices via their
2198 respective on-board firmware and data using other command line
2199 programs in the AltOS software suite.
2202 TeleMini can be communicated with through a TeleDongle device
2203 over the radio link. When first booted, TeleMini listens for a
2204 TeleDongle device and if it receives a packet, it goes into
2205 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
2206 launched. The easiest way to get it talking is to start the
2207 communication link on the TeleDongle and the power up the
2211 To access the device's firmware for configuration you need a terminal
2212 program such as you would use to talk to a modem. The software
2213 authors prefer using the program 'cu' which comes from the UUCP package
2214 on most Unix-like systems such as Linux. An example command line for
2215 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
2216 indicated from running the
2217 ao-list program. Another reasonable terminal program for Linux is
2218 'cutecom'. The default 'escape'
2219 character used by CU (i.e. the character you use to
2220 issue commands to cu itself instead of sending the command as input
2221 to the connected device) is a '~'. You will need this for use in
2222 only two different ways during normal operations. First is to exit
2223 the program by sending a '~.' which is called a 'escape-disconnect'
2224 and allows you to close-out from 'cu'. The
2225 second use will be outlined later.
2228 All of the Altus Metrum devices share the concept of a two level
2229 command set in their firmware.
2230 The first layer has several single letter commands. Once
2231 you are using 'cu' (or 'cutecom') sending (typing) a '?'
2232 returns a full list of these
2233 commands. The second level are configuration sub-commands accessed
2234 using the 'c' command, for
2235 instance typing 'c?' will give you this second level of commands
2236 (all of which require the
2237 letter 'c' to access). Please note that most configuration options
2238 are stored only in Flash memory; TeleDongle doesn't provide any storage
2239 for these options and so they'll all be lost when you unplug it.
2242 Try setting these configuration ('c' or second level menu) values. A good
2243 place to start is by setting your call sign. By default, the boards
2244 use 'N0CALL' which is cute, but not exactly legal!
2245 Spend a few minutes getting comfortable with the units, their
2246 firmware, and 'cu' (or possibly 'cutecom').
2247 For instance, try to send
2248 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
2249 Verify you can connect and disconnect from the units while in your
2250 terminal program by sending the escape-disconnect mentioned above.
2253 To set the radio frequency, use the 'c R' command to specify the
2254 radio transceiver configuration parameter. This parameter is computed
2255 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
2256 the standard calibration reference frequency, 'S', (normally 434.550MHz):
2260 Round the result to the nearest integer value.
2261 As with all 'c' sub-commands, follow this with a 'c w' to write the
2262 change to the parameter block in the on-board flash on
2263 your altimeter board if you want the change to stay in place across reboots.
2266 To set the apogee delay, use the 'c d' command.
2267 As with all 'c' sub-commands, follow this with a 'c w' to write the
2268 change to the parameter block in the on-board DataFlash chip.
2271 To set the main deployment altitude, use the 'c m' command.
2272 As with all 'c' sub-commands, follow this with a 'c w' to write the
2273 change to the parameter block in the on-board DataFlash chip.
2276 To calibrate the radio frequency, connect the UHF antenna port to a
2277 frequency counter, set the board to 434.550MHz, and use the 'C'
2278 command to generate a CW carrier. Wait for the transmitter temperature
2279 to stabilize and the frequency to settle down.
2280 Then, divide 434.550 MHz by the
2281 measured frequency and multiply by the current radio cal value show
2282 in the 'c s' command. For an unprogrammed board, the default value
2283 is 1186611. Take the resulting integer and program it using the 'c f'
2284 command. Testing with the 'C' command again should show a carrier
2285 within a few tens of Hertz of the intended frequency.
2286 As with all 'c' sub-commands, follow this with a 'c w' to write the
2287 change to the parameter block in the on-board DataFlash chip.
2290 Note that the 'reboot' command, which is very useful on the altimeters,
2291 will likely just cause problems with the dongle. The *correct* way
2292 to reset the dongle is just to unplug and re-plug it.
2295 A fun thing to do at the launch site and something you can do while
2296 learning how to use these units is to play with the radio link access
2297 between an altimeter and the TeleDongle. Be aware that you *must* create
2298 some physical separation between the devices, otherwise the link will
2299 not function due to signal overload in the receivers in each device.
2302 Now might be a good time to take a break and read the rest of this
2303 manual, particularly about the two "modes" that the altimeters
2304 can be placed in. TeleMetrum uses the position of the device when booting
2305 up will determine whether the unit is in "pad" or "idle" mode. TeleMini
2306 enters "idle" mode when it receives a command packet within the first 5 seconds
2307 of being powered up, otherwise it enters "pad" mode.
2310 You can access an altimeter in idle mode from the TeleDongle's USB
2311 connection using the radio link
2312 by issuing a 'p' command to the TeleDongle. Practice connecting and
2313 disconnecting ('~~' while using 'cu') from the altimeter. If
2314 you cannot escape out of the "p" command, (by using a '~~' when in
2315 CU) then it is likely that your kernel has issues. Try a newer version.
2318 Using this radio link allows you to configure the altimeter, test
2319 fire e-matches and igniters from the flight line, check pyro-match
2320 continuity and so forth. You can leave the unit turned on while it
2321 is in 'idle mode' and then place the
2322 rocket vertically on the launch pad, walk away and then issue a
2323 reboot command. The altimeter will reboot and start sending data
2324 having changed to the "pad" mode. If the TeleDongle is not receiving
2325 this data, you can disconnect 'cu' from the TeleDongle using the
2326 procedures mentioned above and THEN connect to the TeleDongle from
2327 inside 'ao-view'. If this doesn't work, disconnect from the
2328 TeleDongle, unplug it, and try again after plugging it back in.
2331 In order to reduce the chance of accidental firing of pyrotechnic
2332 charges, the command to fire a charge is intentionally somewhat
2333 difficult to type, and the built-in help is slightly cryptic to
2334 prevent accidental echoing of characters from the help text back at
2335 the board from firing a charge. The command to fire the apogee
2336 drogue charge is 'i DoIt drogue' and the command to fire the main
2337 charge is 'i DoIt main'.
2340 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
2341 and 'ao-view' will both auditorily announce and visually indicate
2343 Now you can launch knowing that you have a good data path and
2344 good satellite lock for flight data and recovery. Remember
2345 you MUST tell ao-view to connect to the TeleDongle explicitly in
2346 order for ao-view to be able to receive data.
2349 The altimeters provide RDF (radio direction finding) tones on
2350 the pad, during descent and after landing. These can be used to
2351 locate the rocket using a directional antenna; the signal
2352 strength providing an indication of the direction from receiver to rocket.
2355 TeleMetrum also provides GPS tracking data, which can further simplify
2356 locating the rocket once it has landed. (The last good GPS data
2357 received before touch-down will be on the data screen of 'ao-view'.)
2360 Once you have recovered the rocket you can download the eeprom
2361 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
2362 either a USB cable or over the radio link using TeleDongle.
2363 And by following the man page for 'ao-postflight' you can create
2364 various data output reports, graphs, and even KML data to see the
2365 flight trajectory in Google-earth. (Moving the viewing angle making
2366 sure to connect the yellow lines while in Google-earth is the proper
2370 As for ao-view.... some things are in the menu but don't do anything
2371 very useful. The developers have stopped working on ao-view to focus
2372 on a new, cross-platform ground station program. So ao-view may or
2373 may not be updated in the future. Mostly you just use
2374 the Log and Device menus. It has a wonderful display of the incoming
2375 flight data and I am sure you will enjoy what it has to say to you
2376 once you enable the voice output!
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