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5 <title>The Altus Metrum System</title>
6 <subtitle>An Owner's Manual for TeleMetrum, TeleMini and TeleDongle Devices</subtitle>
9 <firstname>Bdale</firstname>
10 <surname>Garbee</surname>
13 <firstname>Keith</firstname>
14 <surname>Packard</surname>
17 <firstname>Bob</firstname>
18 <surname>Finch</surname>
21 <firstname>Anthony</firstname>
22 <surname>Towns</surname>
26 <holder>Bdale Garbee and Keith Packard</holder>
30 This document is released under the terms of the
31 <ulink url="http://creativecommons.org/licenses/by-sa/3.0/">
32 Creative Commons ShareAlike 3.0
39 <revnumber>1.1.1</revnumber>
40 <date>16 September 2012</date>
42 Updated for software version 1.1.1 Version 1.1.1 fixes a few
43 bugs found in version 1.1.
47 <revnumber>1.1</revnumber>
48 <date>13 September 2012</date>
50 Updated for software version 1.1. Version 1.1 has new
51 features but is otherwise compatible with version 1.0.
55 <revnumber>1.0</revnumber>
56 <date>24 August 2011</date>
58 Updated for software version 1.0. Note that 1.0 represents a
59 telemetry format change, meaning both ends of a link
60 (TeleMetrum/TeleMini and TeleDongle) must be updated or
61 communications will fail.
65 <revnumber>0.9</revnumber>
66 <date>18 January 2011</date>
68 Updated for software version 0.9. Note that 0.9 represents a
69 telemetry format change, meaning both ends of a link (TeleMetrum and
70 TeleDongle) must be updated or communications will fail.
74 <revnumber>0.8</revnumber>
75 <date>24 November 2010</date>
76 <revremark>Updated for software version 0.8 </revremark>
82 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing "The
83 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
84 Kit" which formed the basis of the original Getting Started chapter
85 in this manual. Bob was one of our first customers for a production
86 TeleMetrum, and his continued enthusiasm and contributions
87 are immensely gratifying and highly appreciated!
90 And thanks to Anthony (AJ) Towns for major contributions including
91 the AltosUI graphing and site map code and associated documentation.
92 Free software means that our customers and friends can become our
93 collaborators, and we certainly appreciate this level of
97 Have fun using these products, and we hope to meet all of you
98 out on the rocket flight line somewhere.
101 NAR #87103, TRA #12201
103 Keith Packard, KD7SQG
104 NAR #88757, TRA #12200
109 <title>Introduction and Overview</title>
111 Welcome to the Altus Metrum community! Our circuits and software reflect
112 our passion for both hobby rocketry and Free Software. We hope their
113 capabilities and performance will delight you in every way, but by
114 releasing all of our hardware and software designs under open licenses,
115 we also hope to empower you to take as active a role in our collective
119 The first device created for our community was TeleMetrum, a dual
120 deploy altimeter with fully integrated GPS and radio telemetry
121 as standard features, and a "companion interface" that will
122 support optional capabilities in the future.
125 The newest device is TeleMini, a dual deploy altimeter with
126 radio telemetry and radio direction finding. This device is only
127 13mm by 38mm (½ inch by 1½ inches) and can fit easily in an 18mm
131 Complementing TeleMetrum and TeleMini is TeleDongle, a USB to RF
132 interface for communicating with the altimeters. Combined with your
133 choice of antenna and
134 notebook computer, TeleDongle and our associated user interface software
135 form a complete ground station capable of logging and displaying in-flight
136 telemetry, aiding rocket recovery, then processing and archiving flight
137 data for analysis and review.
140 More products will be added to the Altus Metrum family over time, and
141 we currently envision that this will be a single, comprehensive manual
142 for the entire product family.
146 <title>Getting Started</title>
148 The first thing to do after you check the inventory of parts in your
149 "starter kit" is to charge the battery.
152 The TeleMetrum battery can be charged by plugging it into the
153 corresponding socket of the TeleMetrum and then using the USB A to
155 cable to plug the TeleMetrum into your computer's USB socket. The
156 TeleMetrum circuitry will charge the battery whenever it is plugged
157 in, because the TeleMetrum's on-off switch does NOT control the
161 When the GPS chip is initially searching for
162 satellites, TeleMetrum will consume more current than it can pull
163 from the USB port, so the battery must be attached in order to get
164 satellite lock. Once GPS is locked, the current consumption goes back
165 down enough to enable charging while
166 running. So it's a good idea to fully charge the battery as your
167 first item of business so there is no issue getting and maintaining
168 satellite lock. The yellow charge indicator led will go out when the
169 battery is nearly full and the charger goes to trickle charge. It
170 can take several hours to fully recharge a deeply discharged battery.
173 The TeleMini battery can be charged by disconnecting it from the
174 TeleMini board and plugging it into a standalone battery charger
175 board, and connecting that via a USB cable to a laptop or other USB
179 The other active device in the starter kit is the TeleDongle USB to
180 RF interface. If you plug it in to your Mac or Linux computer it should
181 "just work", showing up as a serial port device. Windows systems need
182 driver information that is part of the AltOS download to know that the
183 existing USB modem driver will work. We therefore recommend installing
184 our software before plugging in TeleDongle if you are using a Windows
185 computer. If you are using Linux and are having problems, try moving
186 to a fresher kernel (2.6.33 or newer), as the USB serial driver had
187 ugly bugs in some earlier versions.
190 Next you should obtain and install the AltOS software. These include
191 the AltosUI ground station program, current firmware images for
192 TeleMetrum, TeleMini and TeleDongle, and a number of standalone
193 utilities that are rarely needed. Pre-built binary packages are
194 available for Linux, Microsoft Windows, and recent MacOSX versions.
195 Full source code and build instructions are also available.
196 The latest version may always be downloaded from
197 <ulink url="http://altusmetrum.org/AltOS"/>.
201 <title>Handling Precautions</title>
203 All Altus Metrum products are sophisticated electronic devices.
204 When handled gently and properly installed in an air-frame, they
205 will deliver impressive results. However, as with all electronic
206 devices, there are some precautions you must take.
209 The Lithium Polymer rechargeable batteries have an
210 extraordinary power density. This is great because we can fly with
211 much less battery mass than if we used alkaline batteries or previous
212 generation rechargeable batteries... but if they are punctured
213 or their leads are allowed to short, they can and will release their
215 Thus we recommend that you take some care when handling our batteries
216 and consider giving them some extra protection in your air-frame. We
217 often wrap them in suitable scraps of closed-cell packing foam before
218 strapping them down, for example.
221 The barometric sensors used on both TeleMetrum and TeleMini are
222 sensitive to sunlight. In normal TeleMetrum mounting situations, it
223 and all of the other surface mount components
224 are "down" towards whatever the underlying mounting surface is, so
225 this is not normally a problem. Please consider this, though, when
226 designing an installation, for example, in an air-frame with a
227 see-through plastic payload bay. It is particularly important to
228 consider this with TeleMini, both because the baro sensor is on the
229 "top" of the board, and because many model rockets with payload bays
230 use clear plastic for the payload bay! Replacing these with an opaque
231 cardboard tube, painting them, or wrapping them with a layer of masking
232 tape are all reasonable approaches to keep the sensor out of direct
236 The barometric sensor sampling port must be able to "breathe",
237 both by not being covered by foam or tape or other materials that might
238 directly block the hole on the top of the sensor, and also by having a
239 suitable static vent to outside air.
242 As with all other rocketry electronics, Altus Metrum altimeters must
243 be protected from exposure to corrosive motor exhaust and ejection
248 <title>Hardware Overview</title>
250 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
251 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
252 small in diameter may require some creativity in mounting and wiring
253 to succeed! The presence of an accelerometer means TeleMetrum should
254 be aligned along the flight axis of the airframe, and by default the 1/4
255 wave UHF wire antenna should be on the nose-cone end of the board. The
256 antenna wire is about 7 inches long, and wiring for a power switch and
257 the e-matches for apogee and main ejection charges depart from the
258 fin can end of the board, meaning an ideal "simple" avionics
259 bay for TeleMetrum should have at least 10 inches of interior length.
262 TeleMini is a 0.5 inch by 1.5 inch circuit board. It was designed to
263 fit inside an 18mm air-frame tube, but using it in a tube that
264 small in diameter may require some creativity in mounting and wiring
265 to succeed! Since there is no accelerometer, TeleMini can be mounted
266 in any convenient orientation. The default 1/4
267 wave UHF wire antenna attached to the center of one end of
268 the board is about 7 inches long, and wiring for a power switch and
269 the e-matches for apogee and main ejection charges depart from the
270 other end of the board, meaning an ideal "simple" avionics
271 bay for TeleMini should have at least 9 inches of interior length.
274 A typical TeleMetrum or TeleMini installation involves attaching
275 only a suitable Lithium Polymer battery, a single pole switch for
276 power on/off, and two pairs of wires connecting e-matches for the
277 apogee and main ejection charges. All Altus Metrum products are
278 designed for use with single-cell batteries with 3.7 volts nominal.
281 By default, we use the unregulated output of the Li-Po battery directly
282 to fire ejection charges. This works marvelously with standard
283 low-current e-matches like the J-Tek from MJG Technologies, and with
284 Quest Q2G2 igniters. However, if you want or need to use a separate
285 pyro battery, check out the "External Pyro Battery" section in this
286 manual for instructions on how to wire that up. The altimeters are
287 designed to work with an external pyro battery of no more than 15 volts.
290 Ejection charges are wired directly to the screw terminal block
291 at the aft end of the altimeter. You'll need a very small straight
292 blade screwdriver for these screws, such as you might find in a
293 jeweler's screwdriver set.
296 TeleMetrum also uses the screw terminal block for the power
297 switch leads. On TeleMini, the power switch leads are soldered
298 directly to the board and can be connected directly to a switch.
301 For most air-frames, the integrated antennas are more than
302 adequate. However, if you are installing in a carbon-fiber or
303 metal electronics bay which is opaque to RF signals, you may need to
304 use off-board external antennas instead. In this case, you can
305 order an altimeter with an SMA connector for the UHF antenna
306 connection, and, on TeleMetrum, you can unplug the integrated GPS
307 antenna and select an appropriate off-board GPS antenna with
308 cable terminating in a U.FL connector.
312 <title>System Operation</title>
314 <title>Firmware Modes </title>
316 The AltOS firmware build for the altimeters has two
317 fundamental modes, "idle" and "flight". Which of these modes
318 the firmware operates in is determined at start up time. For
319 TeleMetrum, the mode is controlled by the orientation of the
320 rocket (well, actually the board, of course...) at the time
321 power is switched on. If the rocket is "nose up", then
322 TeleMetrum assumes it's on a rail or rod being prepared for
323 launch, so the firmware chooses flight mode. However, if the
324 rocket is more or less horizontal, the firmware instead enters
325 idle mode. Since TeleMini doesn't have an accelerometer we can
326 use to determine orientation, "idle" mode is selected when the
327 board receives a command packet within the first five seconds
328 of operation; if no packet is received, the board enters
332 At power on, you will hear three beeps or see three flashes
333 ("S" in Morse code for start up) and then a pause while
334 the altimeter completes initialization and self test, and decides
335 which mode to enter next.
338 In flight or "pad" mode, the altimeter engages the flight
339 state machine, goes into transmit-only mode to
340 send telemetry, and waits for launch to be detected.
341 Flight mode is indicated by an "di-dah-dah-dit" ("P" for pad)
342 on the beeper or lights, followed by beeps or flashes
343 indicating the state of the pyrotechnic igniter continuity.
344 One beep/flash indicates apogee continuity, two beeps/flashes
345 indicate main continuity, three beeps/flashes indicate both
346 apogee and main continuity, and one longer "brap" sound or
347 rapidly alternating lights indicates no continuity. For a
348 dual deploy flight, make sure you're getting three beeps or
349 flashes before launching! For apogee-only or motor eject
350 flights, do what makes sense.
353 If idle mode is entered, you will hear an audible "di-dit" or see
354 two short flashes ("I" for idle), and the flight state machine is
355 disengaged, thus no ejection charges will fire. The altimeters also
356 listen for the radio link when in idle mode for requests sent via
357 TeleDongle. Commands can be issued to a TeleMetrum in idle mode
359 USB or the radio link equivalently. TeleMini only has the radio link.
360 Idle mode is useful for configuring the altimeter, for extracting data
361 from the on-board storage chip after flight, and for ground testing
365 One "neat trick" of particular value when TeleMetrum is used with
366 very large air-frames, is that you can power the board up while the
367 rocket is horizontal, such that it comes up in idle mode. Then you can
368 raise the air-frame to launch position, and issue a 'reset' command
369 via TeleDongle over the radio link to cause the altimeter to reboot and
370 come up in flight mode. This is much safer than standing on the top
371 step of a rickety step-ladder or hanging off the side of a launch
372 tower with a screw-driver trying to turn on your avionics before
379 TeleMetrum includes a complete GPS receiver. A complete explanation
380 of how GPS works is beyond the scope of this manual, but the bottom
381 line is that the TeleMetrum GPS receiver needs to lock onto at least
382 four satellites to obtain a solid 3 dimensional position fix and know
386 TeleMetrum provides backup power to the GPS chip any time a
387 battery is connected. This allows the receiver to "warm start" on
388 the launch rail much faster than if every power-on were a GPS
389 "cold start". In typical operations, powering up TeleMetrum
390 on the flight line in idle mode while performing final air-frame
391 preparation will be sufficient to allow the GPS receiver to cold
392 start and acquire lock. Then the board can be powered down during
393 RSO review and installation on a launch rod or rail. When the board
394 is turned back on, the GPS system should lock very quickly, typically
395 long before igniter installation and return to the flight line are
400 <title>Controlling An Altimeter Over The Radio Link</title>
402 One of the unique features of the Altus Metrum system is
403 the ability to create a two way command link between TeleDongle
404 and an altimeter using the digital radio transceivers built into
405 each device. This allows you to interact with the altimeter from
406 afar, as if it were directly connected to the computer.
409 Any operation which can be performed with TeleMetrum can
410 either be done with TeleMetrum directly connected to the
411 computer via the USB cable, or through the radio
412 link. TeleMini doesn't provide a USB connector and so it is
413 always communicated with over radio. Select the appropriate
414 TeleDongle device when the list of devices is presented and
415 AltosUI will interact with an altimeter over the radio link.
418 One oddity in the current interface is how AltosUI selects the
419 frequency for radio communications. Instead of providing
420 an interface to specifically configure the frequency, it uses
421 whatever frequency was most recently selected for the target
422 TeleDongle device in Monitor Flight mode. If you haven't ever
423 used that mode with the TeleDongle in question, select the
424 Monitor Flight button from the top level UI, and pick the
425 appropriate TeleDongle device. Once the flight monitoring
426 window is open, select the desired frequency and then close it
427 down again. All radio communications will now use that frequency.
432 Save Flight Data—Recover flight data from the rocket without
438 Configure altimeter apogee delays or main deploy heights
439 to respond to changing launch conditions. You can also
440 'reboot' the altimeter. Use this to remotely enable the
441 flight computer by turning TeleMetrum on in "idle" mode,
442 then once the air-frame is oriented for launch, you can
443 reboot the altimeter and have it restart in pad mode
444 without having to climb the scary ladder.
449 Fire Igniters—Test your deployment charges without snaking
450 wires out through holes in the air-frame. Simply assembly the
451 rocket as if for flight with the apogee and main charges
452 loaded, then remotely command the altimeter to fire the
458 Operation over the radio link for configuring an altimeter, ground
459 testing igniters, and so forth uses the same RF frequencies as flight
460 telemetry. To configure the desired TeleDongle frequency, select
461 the monitor flight tab, then use the frequency selector and
462 close the window before performing other desired radio operations.
465 TeleMetrum only enables radio commanding in 'idle' mode, so
466 make sure you have TeleMetrum lying horizontally when you turn
467 it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
468 flight, and will not be listening for command packets from TeleDongle.
471 TeleMini listens for a command packet for five seconds after
472 first being turned on, if it doesn't hear anything, it enters
473 'pad' mode, ready for flight and will no longer listen for
474 command packets. The easiest way to connect to TeleMini is to
475 initiate the command and select the TeleDongle device. At this
476 point, the TeleDongle will be attempting to communicate with
477 the TeleMini. Now turn TeleMini on, and it should immediately
478 start communicating with the TeleDongle and the desired
479 operation can be performed.
482 You can monitor the operation of the radio link by watching the
483 lights on the devices. The red LED will flash each time a packet
484 is tramsitted, while the green LED will light up on TeleDongle when
485 it is waiting to receive a packet from the altimeter.
489 <title>Ground Testing </title>
491 An important aspect of preparing a rocket using electronic deployment
492 for flight is ground testing the recovery system. Thanks
493 to the bi-directional radio link central to the Altus Metrum system,
494 this can be accomplished in a TeleMetrum or TeleMini equipped rocket
495 with less work than you may be accustomed to with other systems. It
499 Just prep the rocket for flight, then power up the altimeter
500 in "idle" mode (placing air-frame horizontal for TeleMetrum or
501 selected the Configure Altimeter tab for TeleMini). This will cause
502 the firmware to go into "idle" mode, in which the normal flight
503 state machine is disabled and charges will not fire without
504 manual command. You can now command the altimeter to fire the apogee
505 or main charges from a safe distance using your computer and
506 TeleDongle and the Fire Igniter tab to complete ejection testing.
510 <title>Radio Link </title>
512 The chip our boards are based on incorporates an RF transceiver, but
513 it's not a full duplex system... each end can only be transmitting or
514 receiving at any given moment. So we had to decide how to manage the
518 By design, the altimeter firmware listens for the radio link when
519 it's in "idle mode", which
520 allows us to use the radio link to configure the rocket, do things like
521 ejection tests, and extract data after a flight without having to
522 crack open the air-frame. However, when the board is in "flight
523 mode", the altimeter only
524 transmits and doesn't listen at all. That's because we want to put
525 ultimate priority on event detection and getting telemetry out of
527 the radio in case the rocket crashes and we aren't able to extract
531 We don't use a 'normal packet radio' mode like APRS because they're
532 just too inefficient. The GFSK modulation we use is FSK with the
533 base-band pulses passed through a
534 Gaussian filter before they go into the modulator to limit the
535 transmitted bandwidth. When combined with the hardware forward error
536 correction support in the cc1111 chip, this allows us to have a very
537 robust 38.4 kilobit data link with only 10 milliwatts of transmit
538 power, a whip antenna in the rocket, and a hand-held Yagi on the
539 ground. We've had flights to above 21k feet AGL with great reception,
540 and calculations suggest we should be good to well over 40k feet AGL
541 with a 5-element yagi on the ground. We hope to fly boards to higher
542 altitudes over time, and would of course appreciate customer feedback
543 on performance in higher altitude flights!
547 <title>Configurable Parameters</title>
549 Configuring an Altus Metrum altimeter for flight is very
550 simple. Even on our baro-only TeleMini board, the use of a Kalman
551 filter means there is no need to set a "mach delay". The few
552 configurable parameters can all be set using AltosUI over USB or
553 or radio link via TeleDongle.
556 <title>Radio Frequency</title>
558 Altus Metrum boards support radio frequencies in the 70cm
559 band. By default, the configuration interface provides a
560 list of 10 "standard" frequencies in 100kHz channels starting at
561 434.550MHz. However, the firmware supports use of
562 any 50kHz multiple within the 70cm band. At any given
563 launch, we highly recommend coordinating when and by whom each
564 frequency will be used to avoid interference. And of course, both
565 altimeter and TeleDongle must be configured to the same
566 frequency to successfully communicate with each other.
570 <title>Apogee Delay</title>
572 Apogee delay is the number of seconds after the altimeter detects flight
573 apogee that the drogue charge should be fired. In most cases, this
574 should be left at the default of 0. However, if you are flying
575 redundant electronics such as for an L3 certification, you may wish
576 to set one of your altimeters to a positive delay so that both
577 primary and backup pyrotechnic charges do not fire simultaneously.
580 The Altus Metrum apogee detection algorithm fires exactly at
581 apogee. If you are also flying an altimeter like the
582 PerfectFlite MAWD, which only supports selecting 0 or 1
583 seconds of apogee delay, you may wish to set the MAWD to 0
584 seconds delay and set the TeleMetrum to fire your backup 2
585 or 3 seconds later to avoid any chance of both charges
586 firing simultaneously. We've flown several air-frames this
587 way quite happily, including Keith's successful L3 cert.
591 <title>Main Deployment Altitude</title>
593 By default, the altimeter will fire the main deployment charge at an
594 elevation of 250 meters (about 820 feet) above ground. We think this
595 is a good elevation for most air-frames, but feel free to change this
596 to suit. In particular, if you are flying two altimeters, you may
598 deployment elevation for the backup altimeter to be something lower
599 than the primary so that both pyrotechnic charges don't fire
604 <title>Maximum Flight Log</title>
606 TeleMetrum version 1.1 and 1.2 have 2MB of on-board flash storage,
607 enough to hold over 40 minutes of data at full data rate
608 (100 samples/second). TeleMetrum 1.0 has 1MB of on-board
609 storage. As data are stored at a reduced rate during descent
610 (10 samples/second), there's plenty of space to store many
611 flights worth of data.
614 The on-board flash is partitioned into separate flight logs,
615 each of a fixed maximum size. Increase the maximum size of
616 each log and you reduce the number of flights that can be
617 stored. Decrease the size and TeleMetrum can store more
621 All of the configuration data is also stored in the flash
622 memory, which consumes 64kB on TeleMetrum v1.1/v1.2 and 256B on
623 TeleMetrum v1.0. This configuration space is not available
624 for storing flight log data.
627 To compute the amount of space needed for a single flight,
628 you can multiply the expected ascent time (in seconds) by
629 800, multiply the expected descent time (in seconds) by 80
630 and add the two together. That will slightly under-estimate
631 the storage (in bytes) needed for the flight. For instance,
632 a flight spending 20 seconds in ascent and 150 seconds in
633 descent will take about (20 * 800) + (150 * 80) = 28000
634 bytes of storage. You could store dozens of these flights in
638 The default size, 192kB, allows for 10 flights of storage on
639 TeleMetrum v1.1/v1.2 and 5 flights on TeleMetrum v1.0. This
640 ensures that you won't need to erase the memory before
641 flying each time while still allowing more than sufficient
642 storage for each flight.
645 As TeleMini does not contain an accelerometer, it stores
646 data at 10 samples per second during ascent and one sample
647 per second during descent. Each sample is a two byte reading
648 from the barometer. These are stored in 5kB of
649 on-chip flash memory which can hold 256 seconds at the
650 ascent rate or 2560 seconds at the descent rate. Because of
651 the limited storage, TeleMini cannot hold data for more than
652 one flight, and so must be erased after each flight or it
653 will not capture data for subsequent flights.
657 <title>Ignite Mode</title>
659 Instead of firing one charge at apogee and another charge at
660 a fixed height above the ground, you can configure the
661 altimeter to fire both at apogee or both during
662 descent. This was added to support an airframe that has two
663 TeleMetrum computers, one in the fin can and one in the
667 Providing the ability to use both igniters for apogee or
668 main allows some level of redundancy without needing two
669 flight computers. In Redundant Apogee or Redundant Main
670 mode, the two charges will be fired two seconds apart.
674 <title>Pad Orientation</title>
676 TeleMetrum measures acceleration along the axis of the
677 board. Which way the board is oriented affects the sign of
678 the acceleration value. Instead of trying to guess which way
679 the board is mounted in the air frame, TeleMetrum must be
680 explicitly configured for either Antenna Up or Antenna
681 Down. The default, Antenna Up, expects the end of the
682 TeleMetrum board connected to the 70cm antenna to be nearest
683 the nose of the rocket, with the end containing the screw
684 terminals nearest the tail.
692 <title>AltosUI</title>
694 The AltosUI program provides a graphical user interface for
695 interacting with the Altus Metrum product family, including
696 TeleMetrum, TeleMini and TeleDongle. AltosUI can monitor telemetry data,
697 configure TeleMetrum, TeleMini and TeleDongle devices and many other
698 tasks. The primary interface window provides a selection of
699 buttons, one for each major activity in the system. This manual
700 is split into chapters, each of which documents one of the tasks
701 provided from the top-level toolbar.
704 <title>Monitor Flight</title>
705 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
707 Selecting this item brings up a dialog box listing all of the
708 connected TeleDongle devices. When you choose one of these,
709 AltosUI will create a window to display telemetry data as
710 received by the selected TeleDongle device.
713 All telemetry data received are automatically recorded in
714 suitable log files. The name of the files includes the current
715 date and rocket serial and flight numbers.
718 The radio frequency being monitored by the TeleDongle device is
719 displayed at the top of the window. You can configure the
720 frequency by clicking on the frequency box and selecting the desired
721 frequency. AltosUI remembers the last frequency selected for each
722 TeleDongle and selects that automatically the next time you use
726 Below the TeleDongle frequency selector, the window contains a few
727 significant pieces of information about the altimeter providing
728 the telemetry data stream:
732 <para>The configured call-sign</para>
735 <para>The device serial number</para>
738 <para>The flight number. Each altimeter remembers how many
744 The rocket flight state. Each flight passes through several
745 states including Pad, Boost, Fast, Coast, Drogue, Main and
751 The Received Signal Strength Indicator value. This lets
752 you know how strong a signal TeleDongle is receiving. The
753 radio inside TeleDongle operates down to about -99dBm;
754 weaker signals may not be receivable. The packet link uses
755 error detection and correction techniques which prevent
756 incorrect data from being reported.
761 Finally, the largest portion of the window contains a set of
762 tabs, each of which contain some information about the rocket.
763 They're arranged in 'flight order' so that as the flight
764 progresses, the selected tab automatically switches to display
765 data relevant to the current state of the flight. You can select
766 other tabs at any time. The final 'table' tab displays all of
767 the raw telemetry values in one place in a spreadsheet-like format.
770 <title>Launch Pad</title>
772 The 'Launch Pad' tab shows information used to decide when the
773 rocket is ready for flight. The first elements include red/green
774 indicators, if any of these is red, you'll want to evaluate
775 whether the rocket is ready to launch:
779 Battery Voltage. This indicates whether the Li-Po battery
780 powering the TeleMetrum has sufficient charge to last for
781 the duration of the flight. A value of more than
782 3.7V is required for a 'GO' status.
787 Apogee Igniter Voltage. This indicates whether the apogee
788 igniter has continuity. If the igniter has a low
789 resistance, then the voltage measured here will be close
790 to the Li-Po battery voltage. A value greater than 3.2V is
791 required for a 'GO' status.
796 Main Igniter Voltage. This indicates whether the main
797 igniter has continuity. If the igniter has a low
798 resistance, then the voltage measured here will be close
799 to the Li-Po battery voltage. A value greater than 3.2V is
800 required for a 'GO' status.
805 On-board Data Logging. This indicates whether there is
806 space remaining on-board to store flight data for the
807 upcoming flight. If you've downloaded data, but failed
808 to erase flights, there may not be any space
809 left. TeleMetrum can store multiple flights, depending
810 on the configured maximum flight log size. TeleMini
811 stores only a single flight, so it will need to be
812 downloaded and erased after each flight to capture
813 data. This only affects on-board flight logging; the
814 altimeter will still transmit telemetry and fire
815 ejection charges at the proper times.
820 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
821 currently able to compute position information. GPS requires
822 at least 4 satellites to compute an accurate position.
827 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
828 10 consecutive positions without losing lock. This ensures
829 that the GPS receiver has reliable reception from the
835 The Launchpad tab also shows the computed launch pad position
836 and altitude, averaging many reported positions to improve the
842 <title>Ascent</title>
844 This tab is shown during Boost, Fast and Coast
845 phases. The information displayed here helps monitor the
846 rocket as it heads towards apogee.
849 The height, speed and acceleration are shown along with the
850 maximum values for each of them. This allows you to quickly
851 answer the most commonly asked questions you'll hear during
855 The current latitude and longitude reported by the TeleMetrum GPS are
856 also shown. Note that under high acceleration, these values
857 may not get updated as the GPS receiver loses position
858 fix. Once the rocket starts coasting, the receiver should
859 start reporting position again.
862 Finally, the current igniter voltages are reported as in the
863 Launch Pad tab. This can help diagnose deployment failures
864 caused by wiring which comes loose under high acceleration.
868 <title>Descent</title>
870 Once the rocket has reached apogee and (we hope) activated the
871 apogee charge, attention switches to tracking the rocket on
872 the way back to the ground, and for dual-deploy flights,
873 waiting for the main charge to fire.
876 To monitor whether the apogee charge operated correctly, the
877 current descent rate is reported along with the current
878 height. Good descent rates vary based on the choice of recovery
879 components, but generally range from 15-30m/s on drogue and should
880 be below 10m/s when under the main parachute in a dual-deploy flight.
883 For TeleMetrum altimeters, you can locate the rocket in the
884 sky using the elevation and bearing information to figure
885 out where to look. Elevation is in degrees above the
886 horizon. Bearing is reported in degrees relative to true
887 north. Range can help figure out how big the rocket will
888 appear. Ground Distance shows how far it is to a point
889 directly under the rocket and can help figure out where the
890 rocket is likely to land. Note that all of these values are
891 relative to the pad location. If the elevation is near 90°,
892 the rocket is over the pad, not over you.
895 Finally, the igniter voltages are reported in this tab as
896 well, both to monitor the main charge as well as to see what
897 the status of the apogee charge is. Note that some commercial
898 e-matches are designed to retain continuity even after being
899 fired, and will continue to show as green or return from red to
904 <title>Landed</title>
906 Once the rocket is on the ground, attention switches to
907 recovery. While the radio signal is often lost once the
908 rocket is on the ground, the last reported GPS position is
909 generally within a short distance of the actual landing location.
912 The last reported GPS position is reported both by
913 latitude and longitude as well as a bearing and distance from
914 the launch pad. The distance should give you a good idea of
915 whether to walk or hitch a ride. Take the reported
916 latitude and longitude and enter them into your hand-held GPS
917 unit and have that compute a track to the landing location.
920 Both TeleMini and TeleMetrum will continue to transmit RDF
921 tones after landing, allowing you to locate the rocket by
922 following the radio signal if necessary. You may need to get
923 away from the clutter of the flight line, or even get up on
924 a hill (or your neighbor's RV roof) to receive the RDF signal.
927 The maximum height, speed and acceleration reported
928 during the flight are displayed for your admiring observers.
929 The accuracy of these immediate values depends on the quality
930 of your radio link and how many packets were received.
931 Recovering the on-board data after flight will likely yield
932 more precise results.
935 To get more detailed information about the flight, you can
936 click on the 'Graph Flight' button which will bring up a
937 graph window for the current flight.
941 <title>Site Map</title>
943 When the TeleMetrum has a GPS fix, the Site Map tab will map
944 the rocket's position to make it easier for you to locate the
945 rocket, both while it is in the air, and when it has landed. The
946 rocket's state is indicated by color: white for pad, red for
947 boost, pink for fast, yellow for coast, light blue for drogue,
948 dark blue for main, and black for landed.
951 The map's scale is approximately 3m (10ft) per pixel. The map
952 can be dragged using the left mouse button. The map will attempt
953 to keep the rocket roughly centered while data is being received.
956 Images are fetched automatically via the Google Maps Static API,
957 and cached on disk for reuse. If map images cannot be downloaded,
958 the rocket's path will be traced on a dark gray background
962 You can pre-load images for your favorite launch sites
963 before you leave home; check out the 'Preload Maps' section below.
968 <title>Save Flight Data</title>
970 The altimeter records flight data to its internal flash memory.
971 TeleMetrum data is recorded at a much higher rate than the telemetry
972 system can handle, and is not subject to radio drop-outs. As
973 such, it provides a more complete and precise record of the
974 flight. The 'Save Flight Data' button allows you to read the
975 flash memory and write it to disk. As TeleMini has only a barometer, it
976 records data at the same rate as the telemetry signal, but there will be
977 no data lost due to telemetry drop-outs.
980 Clicking on the 'Save Flight Data' button brings up a list of
981 connected TeleMetrum and TeleDongle devices. If you select a
982 TeleMetrum device, the flight data will be downloaded from that
983 device directly. If you select a TeleDongle device, flight data
984 will be downloaded from an altimeter over radio link via the
985 specified TeleDongle. See the chapter on Controlling An Altimeter
986 Over The Radio Link for more information.
989 After the device has been selected, a dialog showing the
990 flight data saved in the device will be shown allowing you to
991 select which flights to download and which to delete. With
992 version 0.9 or newer firmware, you must erase flights in order
993 for the space they consume to be reused by another
994 flight. This prevents accidentally losing flight data
995 if you neglect to download data before flying again. Note that
996 if there is no more space available in the device, then no
997 data will be recorded during the next flight.
1000 The file name for each flight log is computed automatically
1001 from the recorded flight date, altimeter serial number and
1002 flight number information.
1006 <title>Replay Flight</title>
1008 Select this button and you are prompted to select a flight
1009 record file, either a .telem file recording telemetry data or a
1010 .eeprom file containing flight data saved from the altimeter
1014 Once a flight record is selected, the flight monitor interface
1015 is displayed and the flight is re-enacted in real time. Check
1016 the Monitor Flight chapter above to learn how this window operates.
1020 <title>Graph Data</title>
1022 Select this button and you are prompted to select a flight
1023 record file, either a .telem file recording telemetry data or a
1024 .eeprom file containing flight data saved from
1028 Once a flight record is selected, a window with two tabs is
1029 opened. The first tab contains a graph with acceleration
1030 (blue), velocity (green) and altitude (red) of the flight,
1031 measured in metric units. The
1032 apogee(yellow) and main(magenta) igniter voltages are also
1033 displayed; high voltages indicate continuity, low voltages
1034 indicate open circuits. The second tab contains some basic
1038 The graph can be zoomed into a particular area by clicking and
1039 dragging down and to the right. Once zoomed, the graph can be
1040 reset by clicking and dragging up and to the left. Holding down
1041 control and clicking and dragging allows the graph to be panned.
1042 The right mouse button causes a pop-up menu to be displayed, giving
1043 you the option save or print the plot.
1046 Note that telemetry files will generally produce poor graphs
1047 due to the lower sampling rate and missed telemetry packets.
1048 Use saved flight data in .eeprom files for graphing where possible.
1052 <title>Export Data</title>
1054 This tool takes the raw data files and makes them available for
1055 external analysis. When you select this button, you are prompted to
1057 data file (either .eeprom or .telem will do, remember that
1058 .eeprom files contain higher resolution and more continuous
1059 data). Next, a second dialog appears which is used to select
1060 where to write the resulting file. It has a selector to choose
1061 between CSV and KML file formats.
1064 <title>Comma Separated Value Format</title>
1066 This is a text file containing the data in a form suitable for
1067 import into a spreadsheet or other external data analysis
1068 tool. The first few lines of the file contain the version and
1069 configuration information from the altimeter, then
1070 there is a single header line which labels all of the
1071 fields. All of these lines start with a '#' character which
1072 many tools can be configured to skip over.
1075 The remaining lines of the file contain the data, with each
1076 field separated by a comma and at least one space. All of
1077 the sensor values are converted to standard units, with the
1078 barometric data reported in both pressure, altitude and
1079 height above pad units.
1083 <title>Keyhole Markup Language (for Google Earth)</title>
1085 This is the format used by Google Earth to provide an overlay
1086 within that application. With this, you can use Google Earth to
1087 see the whole flight path in 3D.
1092 <title>Configure Altimeter</title>
1094 Select this button and then select either a TeleMetrum or
1095 TeleDongle Device from the list provided. Selecting a TeleDongle
1096 device will use the radio link to configure a remote altimeter.
1099 The first few lines of the dialog provide information about the
1100 connected device, including the product name,
1101 software version and hardware serial number. Below that are the
1102 individual configuration entries.
1105 At the bottom of the dialog, there are four buttons:
1110 Save. This writes any changes to the
1111 configuration parameter block in flash memory. If you don't
1112 press this button, any changes you make will be lost.
1117 Reset. This resets the dialog to the most recently saved values,
1118 erasing any changes you have made.
1123 Reboot. This reboots the device. Use this to
1124 switch from idle to pad mode by rebooting once the rocket is
1125 oriented for flight, or to confirm changes you think you saved
1131 Close. This closes the dialog. Any unsaved changes will be
1137 The rest of the dialog contains the parameters to be configured.
1140 <title>Main Deploy Altitude</title>
1142 This sets the altitude (above the recorded pad altitude) at
1143 which the 'main' igniter will fire. The drop-down menu shows
1144 some common values, but you can edit the text directly and
1145 choose whatever you like. If the apogee charge fires below
1146 this altitude, then the main charge will fire two seconds
1147 after the apogee charge fires.
1151 <title>Apogee Delay</title>
1153 When flying redundant electronics, it's often important to
1154 ensure that multiple apogee charges don't fire at precisely
1155 the same time, as that can over pressurize the apogee deployment
1156 bay and cause a structural failure of the air-frame. The Apogee
1157 Delay parameter tells the flight computer to fire the apogee
1158 charge a certain number of seconds after apogee has been
1163 <title>Radio Frequency</title>
1165 This configures which of the configured frequencies to use for both
1166 telemetry and packet command mode. Note that if you set this
1167 value via packet command mode, you will have to reconfigure
1168 the TeleDongle frequency before you will be able to use packet
1173 <title>Radio Calibration</title>
1175 The radios in every Altus Metrum device are calibrated at the
1176 factory to ensure that they transmit and receive on the
1177 specified frequency. If you need to you can adjust the calibration
1178 by changing this value. Do not do this without understanding what
1179 the value means, read the appendix on calibration and/or the source
1180 code for more information. To change a TeleDongle's calibration,
1181 you must reprogram the unit completely.
1185 <title>Callsign</title>
1187 This sets the call sign included in each telemetry packet. Set this
1188 as needed to conform to your local radio regulations.
1192 <title>Maximum Flight Log Size</title>
1194 This sets the space (in kilobytes) allocated for each flight
1195 log. The available space will be divided into chunks of this
1196 size. A smaller value will allow more flights to be stored,
1197 a larger value will record data from longer flights.
1201 <title>Ignite Mode</title>
1203 TeleMetrum and TeleMini provide two igniter channels as they
1204 were originally designed as dual-deploy flight
1205 computers. This configuration parameter allows the two
1206 channels to be used in different configurations.
1211 Dual Deploy. This is the usual mode of operation; the
1212 'apogee' channel is fired at apogee and the 'main'
1213 channel at the height above ground specified by the
1214 'Main Deploy Altitude' during descent.
1219 Redundant Apogee. This fires both channels at
1220 apogee, the 'apogee' channel first followed after a two second
1221 delay by the 'main' channel.
1226 Redundant Main. This fires both channels at the
1227 height above ground specified by the Main Deploy
1228 Altitude setting during descent. The 'apogee'
1229 channel is fired first, followed after a two second
1230 delay by the 'main' channel.
1236 <title>Pad Orientation</title>
1238 Because it includes an accelerometer, TeleMetrum is
1239 sensitive to the orientation of the board. By default, it
1240 expects the antenna end to point forward. This parameter
1241 allows that default to be changed, permitting the board to
1242 be mounted with the antenna pointing aft instead.
1247 Antenna Up. In this mode, the antenna end of the
1248 TeleMetrum board must point forward, in line with the
1249 expected flight path.
1254 Antenna Down. In this mode, the antenna end of the
1255 TeleMetrum board must point aft, in line with the
1256 expected flight path.
1263 <title>Configure AltosUI</title>
1265 This button presents a dialog so that you can configure the AltosUI global settings.
1268 <title>Voice Settings</title>
1270 AltosUI provides voice announcements during flight so that you
1271 can keep your eyes on the sky and still get information about
1272 the current flight status. However, sometimes you don't want
1277 <para>Enable—turns all voice announcements on and off</para>
1281 Test Voice—Plays a short message allowing you to verify
1282 that the audio system is working and the volume settings
1289 <title>Log Directory</title>
1291 AltosUI logs all telemetry data and saves all TeleMetrum flash
1292 data to this directory. This directory is also used as the
1293 staring point when selecting data files for display or export.
1296 Click on the directory name to bring up a directory choosing
1297 dialog, select a new directory and click 'Select Directory' to
1298 change where AltosUI reads and writes data files.
1302 <title>Callsign</title>
1304 This value is transmitted in each command packet sent from
1305 TeleDongle and received from an altimeter. It is not used in
1306 telemetry mode, as the callsign configured in the altimeter board
1307 is included in all telemetry packets. Configure this
1308 with the AltosUI operators call sign as needed to comply with
1309 your local radio regulations.
1313 <title>Imperial Units</title>
1315 This switches between metric units (meters) and imperial
1316 units (feet and miles). This affects the display of values
1317 use during flight monitoring, data graphing and all of the
1318 voice announcements. It does not change the units used when
1319 exporting to CSV files, those are always produced in metric units.
1323 <title>Font Size</title>
1325 Selects the set of fonts used in the flight monitor
1326 window. Choose between the small, medium and large sets.
1330 <title>Serial Debug</title>
1332 This causes all communication with a connected device to be
1333 dumped to the console from which AltosUI was started. If
1334 you've started it from an icon or menu entry, the output
1335 will simply be discarded. This mode can be useful to debug
1336 various serial communication issues.
1340 <title>Manage Frequencies</title>
1342 This brings up a dialog where you can configure the set of
1343 frequencies shown in the various frequency menus. You can
1344 add as many as you like, or even reconfigure the default
1345 set. Changing this list does not affect the frequency
1346 settings of any devices, it only changes the set of
1347 frequencies shown in the menus.
1352 <title>Configure Groundstation</title>
1354 Select this button and then select a TeleDongle Device from the list provided.
1357 The first few lines of the dialog provide information about the
1358 connected device, including the product name,
1359 software version and hardware serial number. Below that are the
1360 individual configuration entries.
1363 Note that the TeleDongle itself doesn't save any configuration
1364 data, the settings here are recorded on the local machine in
1365 the Java preferences database. Moving the TeleDongle to
1366 another machine, or using a different user account on the same
1367 machine will cause settings made here to have no effect.
1370 At the bottom of the dialog, there are three buttons:
1375 Save. This writes any changes to the
1376 local Java preferences file. If you don't
1377 press this button, any changes you make will be lost.
1382 Reset. This resets the dialog to the most recently saved values,
1383 erasing any changes you have made.
1388 Close. This closes the dialog. Any unsaved changes will be
1394 The rest of the dialog contains the parameters to be configured.
1397 <title>Frequency</title>
1399 This configures the frequency to use for both telemetry and
1400 packet command mode. Set this before starting any operation
1401 involving packet command mode so that it will use the right
1402 frequency. Telemetry monitoring mode also provides a menu to
1403 change the frequency, and that menu also sets the same Java
1404 preference value used here.
1408 <title>Radio Calibration</title>
1410 The radios in every Altus Metrum device are calibrated at the
1411 factory to ensure that they transmit and receive on the
1412 specified frequency. To change a TeleDongle's calibration,
1413 you must reprogram the unit completely, so this entry simply
1414 shows the current value and doesn't allow any changes.
1419 <title>Flash Image</title>
1421 This reprograms any Altus Metrum device by using a TeleMetrum
1422 or TeleDongle as a programming dongle. Please read the
1423 directions for flashing devices in the Updating Device
1424 Firmware chapter below.
1427 Once you have the programmer and target devices connected,
1428 push the 'Flash Image' button. That will present a dialog box
1429 listing all of the connected devices. Carefully select the
1430 programmer device, not the device to be programmed.
1433 Next, select the image to flash to the device. These are named
1434 with the product name and firmware version. The file selector
1435 will start in the directory containing the firmware included
1436 with the AltosUI package. Navigate to the directory containing
1437 the desired firmware if it isn't there.
1440 Next, a small dialog containing the device serial number and
1441 RF calibration values should appear. If these values are
1442 incorrect (possibly due to a corrupted image in the device),
1443 enter the correct values here.
1446 Finally, a dialog containing a progress bar will follow the
1447 programming process.
1450 When programming is complete, the target device will
1451 reboot. Note that if the target device is connected via USB, you
1452 will have to unplug it and then plug it back in for the USB
1453 connection to reset so that you can communicate with the device
1458 <title>Fire Igniter</title>
1460 This activates the igniter circuits in TeleMetrum to help test
1461 recovery systems deployment. Because this command can operate
1462 over the Packet Command Link, you can prepare the rocket as
1463 for flight and then test the recovery system without needing
1464 to snake wires inside the air-frame.
1467 Selecting the 'Fire Igniter' button brings up the usual device
1468 selection dialog. Pick the desired TeleDongle or TeleMetrum
1469 device. This brings up another window which shows the current
1470 continuity test status for both apogee and main charges.
1473 Next, select the desired igniter to fire. This will enable the
1477 Select the 'Arm' button. This enables the 'Fire' button. The
1478 word 'Arm' is replaced by a countdown timer indicating that
1479 you have 10 seconds to press the 'Fire' button or the system
1480 will deactivate, at which point you start over again at
1481 selecting the desired igniter.
1485 <title>Scan Channels</title>
1487 This listens for telemetry packets on all of the configured
1488 frequencies, displaying information about each device it
1489 receives a packet from. You can select which of the three
1490 telemetry formats should be tried; by default, it only listens
1491 for the standard telemetry packets used in v1.0 and later
1496 <title>Load Maps</title>
1498 Before heading out to a new launch site, you can use this to
1499 load satellite images in case you don't have internet
1500 connectivity at the site. This loads a fairly large area
1501 around the launch site, which should cover any flight you're likely to make.
1504 There's a drop-down menu of launch sites we know about; if
1505 your favorites aren't there, please let us know the lat/lon
1506 and name of the site. The contents of this list are actually
1507 downloaded at run-time, so as new sites are sent in, they'll
1508 get automatically added to this list.
1511 If the launch site isn't in the list, you can manually enter the lat/lon values
1514 Clicking the 'Load Map' button will fetch images from Google
1515 Maps; note that Google limits how many images you can fetch at
1516 once, so if you load more than one launch site, you may get
1517 some gray areas in the map which indicate that Google is tired
1518 of sending data to you. Try again later.
1522 <title>Monitor Idle</title>
1524 This brings up a dialog similar to the Monitor Flight UI,
1525 except it works with the altimeter in "idle" mode by sending
1526 query commands to discover the current state rather than
1527 listening for telemetry packets.
1532 <title>Using Altus Metrum Products</title>
1534 <title>Being Legal</title>
1536 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
1537 other authorization to legally operate the radio transmitters that are part
1542 <title>In the Rocket</title>
1544 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
1545 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
1546 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
1547 850mAh battery weighs less than a 9V alkaline battery, and will
1548 run a TeleMetrum for hours.
1549 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
1550 a few hours, or a TeleMini for much (much) longer.
1553 By default, we ship the altimeters with a simple wire antenna. If your
1554 electronics bay or the air-frame it resides within is made of carbon fiber,
1555 which is opaque to RF signals, you may choose to have an SMA connector
1556 installed so that you can run a coaxial cable to an antenna mounted
1557 elsewhere in the rocket.
1561 <title>On the Ground</title>
1563 To receive the data stream from the rocket, you need an antenna and short
1564 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. The
1565 TeleDongle in turn plugs directly into the USB port on a notebook
1566 computer. Because TeleDongle looks like a simple serial port, your computer
1567 does not require special device drivers... just plug it in.
1570 The GUI tool, AltosUI, is written in Java and runs across
1571 Linux, Mac OS and Windows. There's also a suite of C tools
1572 for Linux which can perform most of the same tasks.
1575 After the flight, you can use the radio link to extract the more detailed data
1576 logged in either TeleMetrum or TeleMini devices, 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 Li-Po
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 TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
1584 receiver, so that you can put in a way-point for the last reported rocket
1585 position before touch-down. This makes looking for your rocket a lot like
1586 Geo-Caching... just go to the way-point 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 feed-line
1610 optionally, a hand-held 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- or TeleMini- 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 during the flight itself, and the more
1632 complete data log recorded in the flash memory on the altimeter
1633 board. Once this data is on your computer, our post-flight 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 TeleMetrum data file
1638 usable 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,
1655 We are also working on the design of a hand-held ground terminal that will
1656 allow monitoring the rocket's status, collecting data during flight, and
1657 logging data after flight without the need for a notebook computer on the
1658 flight line. Particularly since it is so difficult to read most notebook
1659 screens in direct sunlight, we think this will be a great thing to have.
1662 Because all of our work is open, both the hardware designs and the software,
1663 if you have some great idea for an addition to the current Altus Metrum family,
1664 feel free to dive in and help! Or let us know what you'd like to see that
1665 we aren't already working on, and maybe we'll get excited about it too...
1670 <title>Altimeter Installation Recommendations</title>
1672 Building high-power rockets that fly safely is hard enough. Mix
1673 in some sophisticated electronics and a bunch of radio energy
1674 and oftentimes you find few perfect solutions. This chapter
1675 contains some suggestions about how to install Altus Metrum
1676 products into the rocket air-frame, including how to safely and
1677 reliably mix a variety of electronics into the same air-frame.
1680 <title>Mounting the Altimeter</title>
1682 The first consideration is to ensure that the altimeter is
1683 securely fastened to the air-frame. For TeleMetrum, we use
1684 nylon standoffs and nylon screws; they're good to at least 50G
1685 and cannot cause any electrical issues on the board. For
1686 TeleMini, we usually cut small pieces of 1/16" balsa to fit
1687 under the screw holes, and then take 2x56 nylon screws and
1688 screw them through the TeleMini mounting holes, through the
1689 balsa and into the underlying material.
1691 <orderedlist inheritnum='inherit' numeration='arabic'>
1693 Make sure TeleMetrum is aligned precisely along the axis of
1694 acceleration so that the accelerometer can accurately
1695 capture data during the flight.
1698 Watch for any metal touching components on the
1699 board. Shorting out connections on the bottom of the board
1700 can cause the altimeter to fail during flight.
1705 <title>Dealing with the Antenna</title>
1707 The antenna supplied is just a piece of solid, insulated,
1708 wire. If it gets damaged or broken, it can be easily
1709 replaced. It should be kept straight and not cut; bending or
1710 cutting it will change the resonant frequency and/or
1711 impedance, making it a less efficient radiator and thus
1712 reducing the range of the telemetry signal.
1715 Keeping metal away from the antenna will provide better range
1716 and a more even radiation pattern. In most rockets, it's not
1717 entirely possible to isolate the antenna from metal
1718 components; there are often bolts, all-thread and wires from other
1719 electronics to contend with. Just be aware that the more stuff
1720 like this around the antenna, the lower the range.
1723 Make sure the antenna is not inside a tube made or covered
1724 with conducting material. Carbon fiber is the most common
1725 culprit here -- CF is a good conductor and will effectively
1726 shield the antenna, dramatically reducing signal strength and
1727 range. Metallic flake paint is another effective shielding
1728 material which is to be avoided around any antennas.
1731 If the ebay is large enough, it can be convenient to simply
1732 mount the altimeter at one end and stretch the antenna out
1733 inside. Taping the antenna to the sled can keep it straight
1734 under acceleration. If there are metal rods, keep the
1735 antenna as far away as possible.
1738 For a shorter ebay, it's quite practical to have the antenna
1739 run through a bulkhead and into an adjacent bay. Drill a small
1740 hole in the bulkhead, pass the antenna wire through it and
1741 then seal it up with glue or clay. We've also used acrylic
1742 tubing to create a cavity for the antenna wire. This works a
1743 bit better in that the antenna is known to stay straight and
1744 not get folded by recovery components in the bay. Angle the
1745 tubing towards the side wall of the rocket and it ends up
1746 consuming very little space.
1749 If you need to place the antenna at a distance from the
1750 altimeter, you can replace the antenna with an edge-mounted
1751 SMA connector, and then run 50Ω coax from the board to the
1752 antenna. Building a remote antenna is beyond the scope of this
1757 <title>Preserving GPS Reception</title>
1759 The GPS antenna and receiver in TeleMetrum are highly
1760 sensitive and normally have no trouble tracking enough
1761 satellites to provide accurate position information for
1762 recovering the rocket. However, there are many ways to
1763 attenuate the GPS signal.
1764 <orderedlist inheritnum='inherit' numeration='arabic'>
1766 Conductive tubing or coatings. Carbon fiber and metal
1767 tubing, or metallic paint will all dramatically attenuate the
1768 GPS signal. We've never heard of anyone successfully
1769 receiving GPS from inside these materials.
1772 Metal components near the GPS patch antenna. These will
1773 de-tune the patch antenna, changing the resonant frequency
1774 away from the L1 carrier and reduce the effectiveness of the
1775 antenna. You can place as much stuff as you like beneath the
1776 antenna as that's covered with a ground plane. But, keep
1777 wires and metal out from above the patch antenna.
1783 <title>Radio Frequency Interference</title>
1785 Any altimeter will generate RFI; the digital circuits use
1786 high-frequency clocks that spray radio interference across a
1787 wide band. Altus Metrum altimeters generate intentional radio
1788 signals as well, increasing the amount of RF energy around the board.
1791 Rocketry altimeters also use precise sensors measuring air
1792 pressure and acceleration. Tiny changes in voltage can cause
1793 these sensor readings to vary by a huge amount. When the
1794 sensors start mis-reporting data, the altimeter can either
1795 fire the igniters at the wrong time, or not fire them at all.
1798 Voltages are induced when radio frequency energy is
1799 transmitted from one circuit to another. Here are things that
1800 influence the induced voltage and current:
1804 Keep wires from different circuits apart. Moving circuits
1805 further apart will reduce RFI.
1808 Avoid parallel wires from different circuits. The longer two
1809 wires run parallel to one another, the larger the amount of
1810 transferred energy. Cross wires at right angles to reduce
1814 Twist wires from the same circuits. Two wires the same
1815 distance from the transmitter will get the same amount of
1816 induced energy which will then cancel out. Any time you have
1817 a wire pair running together, twist the pair together to
1818 even out distances and reduce RFI. For altimeters, this
1819 includes battery leads, switch hookups and igniter
1823 Avoid resonant lengths. Know what frequencies are present
1824 in the environment and avoid having wire lengths near a
1825 natural resonant length. Altusmetrum products transmit on the
1826 70cm amateur band, so you should avoid lengths that are a
1827 simple ratio of that length; essentially any multiple of 1/4
1828 of the wavelength (17.5cm).
1833 <title>The Barometric Sensor</title>
1835 Altusmetrum altimeters measure altitude with a barometric
1836 sensor, essentially measuring the amount of air above the
1837 rocket to figure out how high it is. A large number of
1838 measurements are taken as the altimeter initializes itself to
1839 figure out the pad altitude. Subsequent measurements are then
1840 used to compute the height above the pad.
1843 To accurately measure atmospheric pressure, the ebay
1844 containing the altimeter must be vented outside the
1845 air-frame. The vent must be placed in a region of linear
1846 airflow, have smooth edges, and away from areas of increasing or
1847 decreasing pressure.
1850 The barometric sensor in the altimeter is quite sensitive to
1851 chemical damage from the products of APCP or BP combustion, so
1852 make sure the ebay is carefully sealed from any compartment
1853 which contains ejection charges or motors.
1857 <title>Ground Testing</title>
1859 The most important aspect of any installation is careful
1860 ground testing. Bringing an air-frame up to the LCO table which
1861 hasn't been ground tested can lead to delays or ejection
1862 charges firing on the pad, or, even worse, a recovery system
1866 Do a 'full systems' test that includes wiring up all igniters
1867 without any BP and turning on all of the electronics in flight
1868 mode. This will catch any mistakes in wiring and any residual
1869 RFI issues that might accidentally fire igniters at the wrong
1870 time. Let the air-frame sit for several minutes, checking for
1871 adequate telemetry signal strength and GPS lock. If any igniters
1872 fire unexpectedly, find and resolve the issue before loading any
1876 Ground test the ejection charges. Prepare the rocket for
1877 flight, loading ejection charges and igniters. Completely
1878 assemble the air-frame and then use the 'Fire Igniters'
1879 interface through a TeleDongle to command each charge to
1880 fire. Make sure the charge is sufficient to robustly separate
1881 the air-frame and deploy the recovery system.
1886 <title>Updating Device Firmware</title>
1888 The big concept to understand is that you have to use a
1889 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
1890 and a TeleMetrum or other TeleDongle to program the TeleDongle
1891 Due to limited memory resources in the cc1111, we don't support
1892 programming directly over USB.
1895 You may wish to begin by ensuring you have current firmware images.
1896 These are distributed as part of the AltOS software bundle that
1897 also includes the AltosUI ground station program. Newer ground
1898 station versions typically work fine with older firmware versions,
1899 so you don't need to update your devices just to try out new
1900 software features. You can always download the most recent
1901 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
1904 We recommend updating the altimeter first, before updating TeleDongle.
1907 <title>Updating TeleMetrum Firmware</title>
1908 <orderedlist inheritnum='inherit' numeration='arabic'>
1910 Find the 'programming cable' that you got as part of the starter
1911 kit, that has a red 8-pin MicroMaTch connector on one end and a
1912 red 4-pin MicroMaTch connector on the other end.
1915 Take the 2 screws out of the TeleDongle case to get access
1916 to the circuit board.
1919 Plug the 8-pin end of the programming cable to the
1920 matching connector on the TeleDongle, and the 4-pin end to the
1921 matching connector on the TeleMetrum.
1922 Note that each MicroMaTch connector has an alignment pin that
1923 goes through a hole in the PC board when you have the cable
1927 Attach a battery to the TeleMetrum board.
1930 Plug the TeleDongle into your computer's USB port, and power
1934 Run AltosUI, and select 'Flash Image' from the File menu.
1937 Pick the TeleDongle device from the list, identifying it as the
1941 Select the image you want put on the TeleMetrum, which should have a
1942 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
1943 in the default directory, if not you may have to poke around
1944 your system to find it.
1947 Make sure the configuration parameters are reasonable
1948 looking. If the serial number and/or RF configuration
1949 values aren't right, you'll need to change them.
1952 Hit the 'OK' button and the software should proceed to flash
1953 the TeleMetrum with new firmware, showing a progress bar.
1956 Confirm that the TeleMetrum board seems to have updated OK, which you
1957 can do by plugging in to it over USB and using a terminal program
1958 to connect to the board and issue the 'v' command to check
1962 If something goes wrong, give it another try.
1967 <title>Updating TeleMini Firmware</title>
1968 <orderedlist inheritnum='inherit' numeration='arabic'>
1970 You'll need a special 'programming cable' to reprogram the
1971 TeleMini. It's available on the Altus Metrum web store, or
1972 you can make your own using an 8-pin MicroMaTch connector on
1973 one end and a set of four pins on the other.
1976 Take the 2 screws out of the TeleDongle case to get access
1977 to the circuit board.
1980 Plug the 8-pin end of the programming cable to the matching
1981 connector on the TeleDongle, and the 4-pins into the holes
1982 in the TeleMini circuit board. Note that the MicroMaTch
1983 connector has an alignment pin that goes through a hole in
1984 the PC board when you have the cable oriented correctly, and
1985 that pin 1 on the TeleMini board is marked with a square pad
1986 while the other pins have round pads.
1989 Attach a battery to the TeleMini board.
1992 Plug the TeleDongle into your computer's USB port, and power
1996 Run AltosUI, and select 'Flash Image' from the File menu.
1999 Pick the TeleDongle device from the list, identifying it as the
2003 Select the image you want put on the TeleMini, which should have a
2004 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
2005 in the default directory, if not you may have to poke around
2006 your system to find it.
2009 Make sure the configuration parameters are reasonable
2010 looking. If the serial number and/or RF configuration
2011 values aren't right, you'll need to change them.
2014 Hit the 'OK' button and the software should proceed to flash
2015 the TeleMini with new firmware, showing a progress bar.
2018 Confirm that the TeleMini board seems to have updated OK, which you
2019 can do by configuring it over the radio link through the TeleDongle, or
2020 letting it come up in "flight" mode and listening for telemetry.
2023 If something goes wrong, give it another try.
2028 <title>Updating TeleDongle Firmware</title>
2030 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
2031 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
2033 <orderedlist inheritnum='inherit' numeration='arabic'>
2035 Find the 'programming cable' that you got as part of the starter
2036 kit, that has a red 8-pin MicroMaTch connector on one end and a
2037 red 4-pin MicroMaTch connector on the other end.
2040 Find the USB cable that you got as part of the starter kit, and
2041 plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
2044 Take the 2 screws out of the TeleDongle case to get access
2045 to the circuit board.
2048 Plug the 8-pin end of the programming cable to the
2049 matching connector on the programmer, and the 4-pin end to the
2050 matching connector on the TeleDongle.
2051 Note that each MicroMaTch connector has an alignment pin that
2052 goes through a hole in the PC board when you have the cable
2056 Attach a battery to the TeleMetrum board if you're using one.
2059 Plug both the programmer and the TeleDongle into your computer's USB
2060 ports, and power up the programmer.
2063 Run AltosUI, and select 'Flash Image' from the File menu.
2066 Pick the programmer device from the list, identifying it as the
2070 Select the image you want put on the TeleDongle, which should have a
2071 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
2072 in the default directory, if not you may have to poke around
2073 your system to find it.
2076 Make sure the configuration parameters are reasonable
2077 looking. If the serial number and/or RF configuration
2078 values aren't right, you'll need to change them. The TeleDongle
2079 serial number is on the "bottom" of the circuit board, and can
2080 usually be read through the translucent blue plastic case without
2081 needing to remove the board from the case.
2084 Hit the 'OK' button and the software should proceed to flash
2085 the TeleDongle with new firmware, showing a progress bar.
2088 Confirm that the TeleDongle board seems to have updated OK, which you
2089 can do by plugging in to it over USB and using a terminal program
2090 to connect to the board and issue the 'v' command to check
2091 the version, etc. Once you're happy, remove the programming cable
2092 and put the cover back on the TeleDongle.
2095 If something goes wrong, give it another try.
2099 Be careful removing the programming cable from the locking 8-pin
2100 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
2101 screwdriver or knife blade to gently pry the locking ears out
2102 slightly to extract the connector. We used a locking connector on
2103 TeleMetrum to help ensure that the cabling to companion boards
2104 used in a rocket don't ever come loose accidentally in flight.
2109 <title>Hardware Specifications</title>
2111 <title>TeleMetrum Specifications</title>
2115 Recording altimeter for model rocketry.
2120 Supports dual deployment (can fire 2 ejection charges).
2125 70cm ham-band transceiver for telemetry down-link.
2130 Barometric pressure sensor good to 45k feet MSL.
2135 1-axis high-g accelerometer for motor characterization, capable of
2136 +/- 50g using default part.
2141 On-board, integrated GPS receiver with 5Hz update rate capability.
2146 On-board 1 megabyte non-volatile memory for flight data storage.
2151 USB interface for battery charging, configuration, and data recovery.
2156 Fully integrated support for Li-Po rechargeable batteries.
2161 Uses Li-Po to fire e-matches, can be modified to support
2162 optional separate pyro battery if needed.
2167 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
2173 <title>TeleMini Specifications</title>
2177 Recording altimeter for model rocketry.
2182 Supports dual deployment (can fire 2 ejection charges).
2187 70cm ham-band transceiver for telemetry down-link.
2192 Barometric pressure sensor good to 45k feet MSL.
2197 On-board 5 kilobyte non-volatile memory for flight data storage.
2202 RF interface for battery charging, configuration, and data recovery.
2207 Support for Li-Po rechargeable batteries, using an external charger.
2212 Uses Li-Po to fire e-matches, can be modified to support
2213 optional separate pyro battery if needed.
2218 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
2227 TeleMetrum seems to shut off when disconnected from the
2228 computer. Make sure the battery is adequately charged. Remember the
2229 unit will pull more power than the USB port can deliver before the
2230 GPS enters "locked" mode. The battery charges best when TeleMetrum
2234 It's impossible to stop the TeleDongle when it's in "p" mode, I have
2235 to unplug the USB cable? Make sure you have tried to "escape out" of
2236 this mode. If this doesn't work the reboot procedure for the
2237 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
2238 outgoing buffer IF your "escape out" ('~~') does not work.
2239 At this point using either 'ao-view' (or possibly
2240 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
2244 The amber LED (on the TeleMetrum) lights up when both
2245 battery and USB are connected. Does this mean it's charging?
2246 Yes, the yellow LED indicates the charging at the 'regular' rate.
2247 If the led is out but the unit is still plugged into a USB port,
2248 then the battery is being charged at a 'trickle' rate.
2251 There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
2252 That's the "pad" mode. Weak batteries might be the problem.
2253 It is also possible that the TeleMetrum is horizontal and the output
2254 is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
2255 it received a command packet which would have left it in "pad" mode.
2258 How do I save flight data?
2259 Live telemetry is written to file(s) whenever AltosUI is connected
2260 to the TeleDongle. The file area defaults to ~/TeleMetrum
2261 but is easily changed using the menus in AltosUI. The files that
2262 are written end in '.telem'. The after-flight
2263 data-dumped files will end in .eeprom and represent continuous data
2264 unlike the .telem files that are subject to losses
2265 along the RF data path.
2266 See the above instructions on what and how to save the eeprom stored
2267 data after physically retrieving your altimeter. Make sure to save
2268 the on-board data after each flight; while the TeleMetrum can store
2269 multiple flights, you never know when you'll lose the altimeter...
2273 <title>Notes for Older Software</title>
2276 Before AltosUI was written, using Altus Metrum devices required
2277 some finesse with the Linux command line. There was a limited
2278 GUI tool, ao-view, which provided functionality similar to the
2279 Monitor Flight window in AltosUI, but everything else was a
2280 fairly 80's experience. This appendix includes documentation for
2281 using that software.
2285 Both TeleMetrum and TeleDongle can be directly communicated
2286 with using USB ports. The first thing you should try after getting
2287 both units plugged into to your computer's USB port(s) is to run
2288 'ao-list' from a terminal-window to see what port-device-name each
2289 device has been assigned by the operating system.
2290 You will need this information to access the devices via their
2291 respective on-board firmware and data using other command line
2292 programs in the AltOS software suite.
2295 TeleMini can be communicated with through a TeleDongle device
2296 over the radio link. When first booted, TeleMini listens for a
2297 TeleDongle device and if it receives a packet, it goes into
2298 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
2299 launched. The easiest way to get it talking is to start the
2300 communication link on the TeleDongle and the power up the
2304 To access the device's firmware for configuration you need a terminal
2305 program such as you would use to talk to a modem. The software
2306 authors prefer using the program 'cu' which comes from the UUCP package
2307 on most Unix-like systems such as Linux. An example command line for
2308 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
2309 indicated from running the
2310 ao-list program. Another reasonable terminal program for Linux is
2311 'cutecom'. The default 'escape'
2312 character used by CU (i.e. the character you use to
2313 issue commands to cu itself instead of sending the command as input
2314 to the connected device) is a '~'. You will need this for use in
2315 only two different ways during normal operations. First is to exit
2316 the program by sending a '~.' which is called a 'escape-disconnect'
2317 and allows you to close-out from 'cu'. The
2318 second use will be outlined later.
2321 All of the Altus Metrum devices share the concept of a two level
2322 command set in their firmware.
2323 The first layer has several single letter commands. Once
2324 you are using 'cu' (or 'cutecom') sending (typing) a '?'
2325 returns a full list of these
2326 commands. The second level are configuration sub-commands accessed
2327 using the 'c' command, for
2328 instance typing 'c?' will give you this second level of commands
2329 (all of which require the
2330 letter 'c' to access). Please note that most configuration options
2331 are stored only in Flash memory; TeleDongle doesn't provide any storage
2332 for these options and so they'll all be lost when you unplug it.
2335 Try setting these configuration ('c' or second level menu) values. A good
2336 place to start is by setting your call sign. By default, the boards
2337 use 'N0CALL' which is cute, but not exactly legal!
2338 Spend a few minutes getting comfortable with the units, their
2339 firmware, and 'cu' (or possibly 'cutecom').
2340 For instance, try to send
2341 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
2342 Verify you can connect and disconnect from the units while in your
2343 terminal program by sending the escape-disconnect mentioned above.
2346 To set the radio frequency, use the 'c R' command to specify the
2347 radio transceiver configuration parameter. This parameter is computed
2348 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
2349 the standard calibration reference frequency, 'S', (normally 434.550MHz):
2353 Round the result to the nearest integer value.
2354 As with all 'c' sub-commands, follow this with a 'c w' to write the
2355 change to the parameter block in the on-board flash on
2356 your altimeter board if you want the change to stay in place across reboots.
2359 To set the apogee delay, use the 'c d' command.
2360 As with all 'c' sub-commands, follow this with a 'c w' to write the
2361 change to the parameter block in the on-board DataFlash chip.
2364 To set the main deployment altitude, use the 'c m' command.
2365 As with all 'c' sub-commands, follow this with a 'c w' to write the
2366 change to the parameter block in the on-board DataFlash chip.
2369 To calibrate the radio frequency, connect the UHF antenna port to a
2370 frequency counter, set the board to 434.550MHz, and use the 'C'
2371 command to generate a CW carrier. Wait for the transmitter temperature
2372 to stabilize and the frequency to settle down.
2373 Then, divide 434.550 MHz by the
2374 measured frequency and multiply by the current radio cal value show
2375 in the 'c s' command. For an unprogrammed board, the default value
2376 is 1186611. Take the resulting integer and program it using the 'c f'
2377 command. Testing with the 'C' command again should show a carrier
2378 within a few tens of Hertz of the intended frequency.
2379 As with all 'c' sub-commands, follow this with a 'c w' to write the
2380 change to the parameter block in the on-board DataFlash chip.
2383 Note that the 'reboot' command, which is very useful on the altimeters,
2384 will likely just cause problems with the dongle. The *correct* way
2385 to reset the dongle is just to unplug and re-plug it.
2388 A fun thing to do at the launch site and something you can do while
2389 learning how to use these units is to play with the radio link access
2390 between an altimeter and the TeleDongle. Be aware that you *must* create
2391 some physical separation between the devices, otherwise the link will
2392 not function due to signal overload in the receivers in each device.
2395 Now might be a good time to take a break and read the rest of this
2396 manual, particularly about the two "modes" that the altimeters
2397 can be placed in. TeleMetrum uses the position of the device when booting
2398 up will determine whether the unit is in "pad" or "idle" mode. TeleMini
2399 enters "idle" mode when it receives a command packet within the first 5 seconds
2400 of being powered up, otherwise it enters "pad" mode.
2403 You can access an altimeter in idle mode from the TeleDongle's USB
2404 connection using the radio link
2405 by issuing a 'p' command to the TeleDongle. Practice connecting and
2406 disconnecting ('~~' while using 'cu') from the altimeter. If
2407 you cannot escape out of the "p" command, (by using a '~~' when in
2408 CU) then it is likely that your kernel has issues. Try a newer version.
2411 Using this radio link allows you to configure the altimeter, test
2412 fire e-matches and igniters from the flight line, check pyro-match
2413 continuity and so forth. You can leave the unit turned on while it
2414 is in 'idle mode' and then place the
2415 rocket vertically on the launch pad, walk away and then issue a
2416 reboot command. The altimeter will reboot and start sending data
2417 having changed to the "pad" mode. If the TeleDongle is not receiving
2418 this data, you can disconnect 'cu' from the TeleDongle using the
2419 procedures mentioned above and THEN connect to the TeleDongle from
2420 inside 'ao-view'. If this doesn't work, disconnect from the
2421 TeleDongle, unplug it, and try again after plugging it back in.
2424 In order to reduce the chance of accidental firing of pyrotechnic
2425 charges, the command to fire a charge is intentionally somewhat
2426 difficult to type, and the built-in help is slightly cryptic to
2427 prevent accidental echoing of characters from the help text back at
2428 the board from firing a charge. The command to fire the apogee
2429 drogue charge is 'i DoIt drogue' and the command to fire the main
2430 charge is 'i DoIt main'.
2433 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
2434 and 'ao-view' will both auditorily announce and visually indicate
2436 Now you can launch knowing that you have a good data path and
2437 good satellite lock for flight data and recovery. Remember
2438 you MUST tell ao-view to connect to the TeleDongle explicitly in
2439 order for ao-view to be able to receive data.
2442 The altimeters provide RDF (radio direction finding) tones on
2443 the pad, during descent and after landing. These can be used to
2444 locate the rocket using a directional antenna; the signal
2445 strength providing an indication of the direction from receiver to rocket.
2448 TeleMetrum also provides GPS tracking data, which can further simplify
2449 locating the rocket once it has landed. (The last good GPS data
2450 received before touch-down will be on the data screen of 'ao-view'.)
2453 Once you have recovered the rocket you can download the eeprom
2454 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
2455 either a USB cable or over the radio link using TeleDongle.
2456 And by following the man page for 'ao-postflight' you can create
2457 various data output reports, graphs, and even KML data to see the
2458 flight trajectory in Google-earth. (Moving the viewing angle making
2459 sure to connect the yellow lines while in Google-earth is the proper
2463 As for ao-view.... some things are in the menu but don't do anything
2464 very useful. The developers have stopped working on ao-view to focus
2465 on a new, cross-platform ground station program. So ao-view may or
2466 may not be updated in the future. Mostly you just use
2467 the Log and Device menus. It has a wonderful display of the incoming
2468 flight data and I am sure you will enjoy what it has to say to you
2469 once you enable the voice output!
2473 <title>Calibration</title>
2475 There are only two calibrations required for a TeleMetrum board, and
2476 only one for TeleDongle and TeleMini. All boards are shipped from
2477 the factory pre-calibrated, but the procedures are documented here
2478 in case they are ever needed. Re-calibration is not supported by
2479 AltosUI, you must connect to the board with a serial terminal program
2480 and interact directly with the on-board command interpreter to effect
2484 <title>Radio Frequency</title>
2486 The radio frequency is synthesized from a clock based on the 48 MHz
2487 crystal on the board. The actual frequency of this oscillator
2488 must be measured to generate a calibration constant. While our
2490 bandwidth is wide enough to allow boards to communicate even when
2491 their oscillators are not on exactly the same frequency, performance
2492 is best when they are closely matched.
2493 Radio frequency calibration requires a calibrated frequency counter.
2494 Fortunately, once set, the variation in frequency due to aging and
2495 temperature changes is small enough that re-calibration by customers
2496 should generally not be required.
2499 To calibrate the radio frequency, connect the UHF antenna port to a
2500 frequency counter, set the board to 434.550MHz, and use the 'C'
2501 command in the on-board command interpreter to generate a CW
2502 carrier. For TeleMetrum, this is best done over USB. For TeleMini,
2503 note that the only way to escape the 'C' command is via power cycle
2504 since the board will no longer be listening for commands once it
2505 starts generating a CW carrier.
2508 Wait for the transmitter temperature to stabilize and the frequency
2509 to settle down. Then, divide 434.550 MHz by the
2510 measured frequency and multiply by the current radio cal value show
2511 in the 'c s' command. For an unprogrammed board, the default value
2512 is 1186611. Take the resulting integer and program it using the 'c f'
2513 command. Testing with the 'C' command again should show a carrier
2514 within a few tens of Hertz of the intended frequency.
2515 As with all 'c' sub-commands, follow this with a 'c w' to write the
2516 change to the parameter block in the on-board DataFlash chip.
2519 Note that any time you re-do the radio frequency calibration, the
2520 radio frequency is reset to the default 434.550 Mhz. If you want
2521 to use another frequency, you will have to set that again after
2522 calibration is completed.
2526 <title>TeleMetrum Accelerometer</title>
2528 The TeleMetrum accelerometer we use has its own 5 volt power
2530 the output must be passed through a resistive voltage divider to match
2531 the input of our 3.3 volt ADC. This means that unlike the barometric
2532 sensor, the output of the acceleration sensor is not ratio-metric to
2533 the ADC converter, and calibration is required. Explicitly
2534 calibrating the accelerometers also allows us to load any device
2535 from a Freescale family that includes at least +/- 40g, 50g, 100g,
2536 and 200g parts. Using gravity,
2537 a simple 2-point calibration yields acceptable results capturing both
2538 the different sensitivities and ranges of the different accelerometer
2539 parts and any variation in power supply voltages or resistor values
2540 in the divider network.
2543 To calibrate the acceleration sensor, use the 'c a 0' command. You
2544 will be prompted to orient the board vertically with the UHF antenna
2545 up and press a key, then to orient the board vertically with the
2546 UHF antenna down and press a key. Note that the accuracy of this
2547 calibration depends primarily on how perfectly vertical and still
2548 the board is held during the cal process. As with all 'c'
2549 sub-commands, follow this with a 'c w' to write the
2550 change to the parameter block in the on-board DataFlash chip.
2553 The +1g and -1g calibration points are included in each telemetry
2554 frame and are part of the header stored in onboard flash to be
2555 downloaded after flight. We always store and return raw ADC
2556 samples for each sensor... so nothing is permanently "lost" or
2557 "damaged" if the calibration is poor.
2560 In the unlikely event an accel cal goes badly, it is possible
2561 that TeleMetrum may always come up in 'pad mode' and as such not be
2562 listening to either the USB or radio link. If that happens,
2563 there is a special hook in the firmware to force the board back
2564 in to 'idle mode' so you can re-do the cal. To use this hook, you
2565 just need to ground the SPI clock pin at power-on. This pin is
2566 available as pin 2 on the 8-pin companion connector, and pin 1 is
2567 ground. So either carefully install a fine-gauge wire jumper
2568 between the two pins closest to the index hole end of the 8-pin
2569 connector, or plug in the programming cable to the 8-pin connector
2570 and use a small screwdriver or similar to short the two pins closest
2571 to the index post on the 4-pin end of the programming cable, and
2572 power up the board. It should come up in 'idle mode' (two beeps),
2578 xmlns:xi="http://www.w3.org/2001/XInclude">
2579 <title>Release Notes</title>
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2590 <!-- LocalWords: Altusmetrum
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