1 <?xml version="1.0" encoding="utf-8" ?>
2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "/usr/share/xml/docbook/schema/dtd/4.5/docbookx.dtd">
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 The battery connectors are a standard 2-pin JST connector and
282 match batteries sold by Spark Fun. Other vendors sell similar
283 batteries for RC aircraft using mating connectors, however the
284 polarity for those is generally reversed from the batteries used
285 by Altus Metrum products. In particular, the Tenergy batteries
286 supplied for use in Featherweight flight computers are not
287 compatible with Altus Metrum flight computers or battery
288 chargers. <emphasis>Check polarity before connecting any battery
289 not purchased from Altus Metrum or Spark Fun.</emphasis>
292 By default, we use the unregulated output of the Li-Po battery directly
293 to fire ejection charges. This works marvelously with standard
294 low-current e-matches like the J-Tek from MJG Technologies, and with
295 Quest Q2G2 igniters. However, if you want or need to use a separate
296 pyro battery, check out the "External Pyro Battery" section in this
297 manual for instructions on how to wire that up. The altimeters are
298 designed to work with an external pyro battery of no more than 15 volts.
301 Ejection charges are wired directly to the screw terminal block
302 at the aft end of the altimeter. You'll need a very small straight
303 blade screwdriver for these screws, such as you might find in a
304 jeweler's screwdriver set.
307 TeleMetrum also uses the screw terminal block for the power
308 switch leads. On TeleMini, the power switch leads are soldered
309 directly to the board and can be connected directly to a switch.
312 For most air-frames, the integrated antennas are more than
313 adequate. However, if you are installing in a carbon-fiber or
314 metal electronics bay which is opaque to RF signals, you may need to
315 use off-board external antennas instead. In this case, you can
316 order an altimeter with an SMA connector for the UHF antenna
317 connection, and, on TeleMetrum, you can unplug the integrated GPS
318 antenna and select an appropriate off-board GPS antenna with
319 cable terminating in a U.FL connector.
323 <title>System Operation</title>
325 <title>Firmware Modes </title>
327 The AltOS firmware build for the altimeters has two
328 fundamental modes, "idle" and "flight". Which of these modes
329 the firmware operates in is determined at start up time. For
330 TeleMetrum, the mode is controlled by the orientation of the
331 rocket (well, actually the board, of course...) at the time
332 power is switched on. If the rocket is "nose up", then
333 TeleMetrum assumes it's on a rail or rod being prepared for
334 launch, so the firmware chooses flight mode. However, if the
335 rocket is more or less horizontal, the firmware instead enters
336 idle mode. Since TeleMini doesn't have an accelerometer we can
337 use to determine orientation, "idle" mode is selected when the
338 board receives a command packet within the first five seconds
339 of operation; if no packet is received, the board enters
343 At power on, you will hear three beeps or see three flashes
344 ("S" in Morse code for start up) and then a pause while
345 the altimeter completes initialization and self test, and decides
346 which mode to enter next.
349 In flight or "pad" mode, the altimeter engages the flight
350 state machine, goes into transmit-only mode to
351 send telemetry, and waits for launch to be detected.
352 Flight mode is indicated by an "di-dah-dah-dit" ("P" for pad)
353 on the beeper or lights, followed by beeps or flashes
354 indicating the state of the pyrotechnic igniter continuity.
355 One beep/flash indicates apogee continuity, two beeps/flashes
356 indicate main continuity, three beeps/flashes indicate both
357 apogee and main continuity, and one longer "brap" sound or
358 rapidly alternating lights indicates no continuity. For a
359 dual deploy flight, make sure you're getting three beeps or
360 flashes before launching! For apogee-only or motor eject
361 flights, do what makes sense.
364 If idle mode is entered, you will hear an audible "di-dit" or see
365 two short flashes ("I" for idle), and the flight state machine is
366 disengaged, thus no ejection charges will fire. The altimeters also
367 listen for the radio link when in idle mode for requests sent via
368 TeleDongle. Commands can be issued to a TeleMetrum in idle mode
370 USB or the radio link equivalently. TeleMini only has the radio link.
371 Idle mode is useful for configuring the altimeter, for extracting data
372 from the on-board storage chip after flight, and for ground testing
376 One "neat trick" of particular value when TeleMetrum is used with
377 very large air-frames, is that you can power the board up while the
378 rocket is horizontal, such that it comes up in idle mode. Then you can
379 raise the air-frame to launch position, and issue a 'reset' command
380 via TeleDongle over the radio link to cause the altimeter to reboot and
381 come up in flight mode. This is much safer than standing on the top
382 step of a rickety step-ladder or hanging off the side of a launch
383 tower with a screw-driver trying to turn on your avionics before
390 TeleMetrum includes a complete GPS receiver. A complete explanation
391 of how GPS works is beyond the scope of this manual, but the bottom
392 line is that the TeleMetrum GPS receiver needs to lock onto at least
393 four satellites to obtain a solid 3 dimensional position fix and know
397 TeleMetrum provides backup power to the GPS chip any time a
398 battery is connected. This allows the receiver to "warm start" on
399 the launch rail much faster than if every power-on were a GPS
400 "cold start". In typical operations, powering up TeleMetrum
401 on the flight line in idle mode while performing final air-frame
402 preparation will be sufficient to allow the GPS receiver to cold
403 start and acquire lock. Then the board can be powered down during
404 RSO review and installation on a launch rod or rail. When the board
405 is turned back on, the GPS system should lock very quickly, typically
406 long before igniter installation and return to the flight line are
411 <title>Controlling An Altimeter Over The Radio Link</title>
413 One of the unique features of the Altus Metrum system is
414 the ability to create a two way command link between TeleDongle
415 and an altimeter using the digital radio transceivers built into
416 each device. This allows you to interact with the altimeter from
417 afar, as if it were directly connected to the computer.
420 Any operation which can be performed with TeleMetrum can
421 either be done with TeleMetrum directly connected to the
422 computer via the USB cable, or through the radio
423 link. TeleMini doesn't provide a USB connector and so it is
424 always communicated with over radio. Select the appropriate
425 TeleDongle device when the list of devices is presented and
426 AltosUI will interact with an altimeter over the radio link.
429 One oddity in the current interface is how AltosUI selects the
430 frequency for radio communications. Instead of providing
431 an interface to specifically configure the frequency, it uses
432 whatever frequency was most recently selected for the target
433 TeleDongle device in Monitor Flight mode. If you haven't ever
434 used that mode with the TeleDongle in question, select the
435 Monitor Flight button from the top level UI, and pick the
436 appropriate TeleDongle device. Once the flight monitoring
437 window is open, select the desired frequency and then close it
438 down again. All radio communications will now use that frequency.
443 Save Flight Data—Recover flight data from the rocket without
449 Configure altimeter apogee delays or main deploy heights
450 to respond to changing launch conditions. You can also
451 'reboot' the altimeter. Use this to remotely enable the
452 flight computer by turning TeleMetrum on in "idle" mode,
453 then once the air-frame is oriented for launch, you can
454 reboot the altimeter and have it restart in pad mode
455 without having to climb the scary ladder.
460 Fire Igniters—Test your deployment charges without snaking
461 wires out through holes in the air-frame. Simply assembly the
462 rocket as if for flight with the apogee and main charges
463 loaded, then remotely command the altimeter to fire the
469 Operation over the radio link for configuring an altimeter, ground
470 testing igniters, and so forth uses the same RF frequencies as flight
471 telemetry. To configure the desired TeleDongle frequency, select
472 the monitor flight tab, then use the frequency selector and
473 close the window before performing other desired radio operations.
476 TeleMetrum only enables radio commanding in 'idle' mode, so
477 make sure you have TeleMetrum lying horizontally when you turn
478 it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
479 flight, and will not be listening for command packets from TeleDongle.
482 TeleMini listens for a command packet for five seconds after
483 first being turned on, if it doesn't hear anything, it enters
484 'pad' mode, ready for flight and will no longer listen for
485 command packets. The easiest way to connect to TeleMini is to
486 initiate the command and select the TeleDongle device. At this
487 point, the TeleDongle will be attempting to communicate with
488 the TeleMini. Now turn TeleMini on, and it should immediately
489 start communicating with the TeleDongle and the desired
490 operation can be performed.
493 You can monitor the operation of the radio link by watching the
494 lights on the devices. The red LED will flash each time a packet
495 is tramsitted, while the green LED will light up on TeleDongle when
496 it is waiting to receive a packet from the altimeter.
500 <title>Ground Testing </title>
502 An important aspect of preparing a rocket using electronic deployment
503 for flight is ground testing the recovery system. Thanks
504 to the bi-directional radio link central to the Altus Metrum system,
505 this can be accomplished in a TeleMetrum or TeleMini equipped rocket
506 with less work than you may be accustomed to with other systems. It
510 Just prep the rocket for flight, then power up the altimeter
511 in "idle" mode (placing air-frame horizontal for TeleMetrum or
512 selected the Configure Altimeter tab for TeleMini). This will cause
513 the firmware to go into "idle" mode, in which the normal flight
514 state machine is disabled and charges will not fire without
515 manual command. You can now command the altimeter to fire the apogee
516 or main charges from a safe distance using your computer and
517 TeleDongle and the Fire Igniter tab to complete ejection testing.
521 <title>Radio Link </title>
523 The chip our boards are based on incorporates an RF transceiver, but
524 it's not a full duplex system... each end can only be transmitting or
525 receiving at any given moment. So we had to decide how to manage the
529 By design, the altimeter firmware listens for the radio link when
530 it's in "idle mode", which
531 allows us to use the radio link to configure the rocket, do things like
532 ejection tests, and extract data after a flight without having to
533 crack open the air-frame. However, when the board is in "flight
534 mode", the altimeter only
535 transmits and doesn't listen at all. That's because we want to put
536 ultimate priority on event detection and getting telemetry out of
538 the radio in case the rocket crashes and we aren't able to extract
542 We don't use a 'normal packet radio' mode like APRS because they're
543 just too inefficient. The GFSK modulation we use is FSK with the
544 base-band pulses passed through a
545 Gaussian filter before they go into the modulator to limit the
546 transmitted bandwidth. When combined with the hardware forward error
547 correction support in the cc1111 chip, this allows us to have a very
548 robust 38.4 kilobit data link with only 10 milliwatts of transmit
549 power, a whip antenna in the rocket, and a hand-held Yagi on the
550 ground. We've had flights to above 21k feet AGL with great reception,
551 and calculations suggest we should be good to well over 40k feet AGL
552 with a 5-element yagi on the ground. We hope to fly boards to higher
553 altitudes over time, and would of course appreciate customer feedback
554 on performance in higher altitude flights!
558 <title>Configurable Parameters</title>
560 Configuring an Altus Metrum altimeter for flight is very
561 simple. Even on our baro-only TeleMini board, the use of a Kalman
562 filter means there is no need to set a "mach delay". The few
563 configurable parameters can all be set using AltosUI over USB or
564 or radio link via TeleDongle.
567 <title>Radio Frequency</title>
569 Altus Metrum boards support radio frequencies in the 70cm
570 band. By default, the configuration interface provides a
571 list of 10 "standard" frequencies in 100kHz channels starting at
572 434.550MHz. However, the firmware supports use of
573 any 50kHz multiple within the 70cm band. At any given
574 launch, we highly recommend coordinating when and by whom each
575 frequency will be used to avoid interference. And of course, both
576 altimeter and TeleDongle must be configured to the same
577 frequency to successfully communicate with each other.
581 <title>Apogee Delay</title>
583 Apogee delay is the number of seconds after the altimeter detects flight
584 apogee that the drogue charge should be fired. In most cases, this
585 should be left at the default of 0. However, if you are flying
586 redundant electronics such as for an L3 certification, you may wish
587 to set one of your altimeters to a positive delay so that both
588 primary and backup pyrotechnic charges do not fire simultaneously.
591 The Altus Metrum apogee detection algorithm fires exactly at
592 apogee. If you are also flying an altimeter like the
593 PerfectFlite MAWD, which only supports selecting 0 or 1
594 seconds of apogee delay, you may wish to set the MAWD to 0
595 seconds delay and set the TeleMetrum to fire your backup 2
596 or 3 seconds later to avoid any chance of both charges
597 firing simultaneously. We've flown several air-frames this
598 way quite happily, including Keith's successful L3 cert.
602 <title>Main Deployment Altitude</title>
604 By default, the altimeter will fire the main deployment charge at an
605 elevation of 250 meters (about 820 feet) above ground. We think this
606 is a good elevation for most air-frames, but feel free to change this
607 to suit. In particular, if you are flying two altimeters, you may
609 deployment elevation for the backup altimeter to be something lower
610 than the primary so that both pyrotechnic charges don't fire
615 <title>Maximum Flight Log</title>
617 TeleMetrum version 1.1 and 1.2 have 2MB of on-board flash storage,
618 enough to hold over 40 minutes of data at full data rate
619 (100 samples/second). TeleMetrum 1.0 has 1MB of on-board
620 storage. As data are stored at a reduced rate during descent
621 (10 samples/second), there's plenty of space to store many
622 flights worth of data.
625 The on-board flash is partitioned into separate flight logs,
626 each of a fixed maximum size. Increase the maximum size of
627 each log and you reduce the number of flights that can be
628 stored. Decrease the size and TeleMetrum can store more
632 All of the configuration data is also stored in the flash
633 memory, which consumes 64kB on TeleMetrum v1.1/v1.2 and 256B on
634 TeleMetrum v1.0. This configuration space is not available
635 for storing flight log data.
638 To compute the amount of space needed for a single flight,
639 you can multiply the expected ascent time (in seconds) by
640 800, multiply the expected descent time (in seconds) by 80
641 and add the two together. That will slightly under-estimate
642 the storage (in bytes) needed for the flight. For instance,
643 a flight spending 20 seconds in ascent and 150 seconds in
644 descent will take about (20 * 800) + (150 * 80) = 28000
645 bytes of storage. You could store dozens of these flights in
649 The default size, 192kB, allows for 10 flights of storage on
650 TeleMetrum v1.1/v1.2 and 5 flights on TeleMetrum v1.0. This
651 ensures that you won't need to erase the memory before
652 flying each time while still allowing more than sufficient
653 storage for each flight.
656 As TeleMini does not contain an accelerometer, it stores
657 data at 10 samples per second during ascent and one sample
658 per second during descent. Each sample is a two byte reading
659 from the barometer. These are stored in 5kB of
660 on-chip flash memory which can hold 256 seconds at the
661 ascent rate or 2560 seconds at the descent rate. Because of
662 the limited storage, TeleMini cannot hold data for more than
663 one flight, and so must be erased after each flight or it
664 will not capture data for subsequent flights.
668 <title>Ignite Mode</title>
670 Instead of firing one charge at apogee and another charge at
671 a fixed height above the ground, you can configure the
672 altimeter to fire both at apogee or both during
673 descent. This was added to support an airframe that has two
674 TeleMetrum computers, one in the fin can and one in the
678 Providing the ability to use both igniters for apogee or
679 main allows some level of redundancy without needing two
680 flight computers. In Redundant Apogee or Redundant Main
681 mode, the two charges will be fired two seconds apart.
685 <title>Pad Orientation</title>
687 TeleMetrum measures acceleration along the axis of the
688 board. Which way the board is oriented affects the sign of
689 the acceleration value. Instead of trying to guess which way
690 the board is mounted in the air frame, TeleMetrum must be
691 explicitly configured for either Antenna Up or Antenna
692 Down. The default, Antenna Up, expects the end of the
693 TeleMetrum board connected to the 70cm antenna to be nearest
694 the nose of the rocket, with the end containing the screw
695 terminals nearest the tail.
703 <title>AltosUI</title>
705 The AltosUI program provides a graphical user interface for
706 interacting with the Altus Metrum product family, including
707 TeleMetrum, TeleMini and TeleDongle. AltosUI can monitor telemetry data,
708 configure TeleMetrum, TeleMini and TeleDongle devices and many other
709 tasks. The primary interface window provides a selection of
710 buttons, one for each major activity in the system. This manual
711 is split into chapters, each of which documents one of the tasks
712 provided from the top-level toolbar.
715 <title>Monitor Flight</title>
716 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
718 Selecting this item brings up a dialog box listing all of the
719 connected TeleDongle devices. When you choose one of these,
720 AltosUI will create a window to display telemetry data as
721 received by the selected TeleDongle device.
724 All telemetry data received are automatically recorded in
725 suitable log files. The name of the files includes the current
726 date and rocket serial and flight numbers.
729 The radio frequency being monitored by the TeleDongle device is
730 displayed at the top of the window. You can configure the
731 frequency by clicking on the frequency box and selecting the desired
732 frequency. AltosUI remembers the last frequency selected for each
733 TeleDongle and selects that automatically the next time you use
737 Below the TeleDongle frequency selector, the window contains a few
738 significant pieces of information about the altimeter providing
739 the telemetry data stream:
743 <para>The configured call-sign</para>
746 <para>The device serial number</para>
749 <para>The flight number. Each altimeter remembers how many
755 The rocket flight state. Each flight passes through several
756 states including Pad, Boost, Fast, Coast, Drogue, Main and
762 The Received Signal Strength Indicator value. This lets
763 you know how strong a signal TeleDongle is receiving. The
764 radio inside TeleDongle operates down to about -99dBm;
765 weaker signals may not be receivable. The packet link uses
766 error detection and correction techniques which prevent
767 incorrect data from being reported.
772 Finally, the largest portion of the window contains a set of
773 tabs, each of which contain some information about the rocket.
774 They're arranged in 'flight order' so that as the flight
775 progresses, the selected tab automatically switches to display
776 data relevant to the current state of the flight. You can select
777 other tabs at any time. The final 'table' tab displays all of
778 the raw telemetry values in one place in a spreadsheet-like format.
781 <title>Launch Pad</title>
783 The 'Launch Pad' tab shows information used to decide when the
784 rocket is ready for flight. The first elements include red/green
785 indicators, if any of these is red, you'll want to evaluate
786 whether the rocket is ready to launch:
790 Battery Voltage. This indicates whether the Li-Po battery
791 powering the TeleMetrum has sufficient charge to last for
792 the duration of the flight. A value of more than
793 3.7V is required for a 'GO' status.
798 Apogee Igniter Voltage. This indicates whether the apogee
799 igniter has continuity. If the igniter has a low
800 resistance, then the voltage measured here will be close
801 to the Li-Po battery voltage. A value greater than 3.2V is
802 required for a 'GO' status.
807 Main Igniter Voltage. This indicates whether the main
808 igniter has continuity. If the igniter has a low
809 resistance, then the voltage measured here will be close
810 to the Li-Po battery voltage. A value greater than 3.2V is
811 required for a 'GO' status.
816 On-board Data Logging. This indicates whether there is
817 space remaining on-board to store flight data for the
818 upcoming flight. If you've downloaded data, but failed
819 to erase flights, there may not be any space
820 left. TeleMetrum can store multiple flights, depending
821 on the configured maximum flight log size. TeleMini
822 stores only a single flight, so it will need to be
823 downloaded and erased after each flight to capture
824 data. This only affects on-board flight logging; the
825 altimeter will still transmit telemetry and fire
826 ejection charges at the proper times.
831 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
832 currently able to compute position information. GPS requires
833 at least 4 satellites to compute an accurate position.
838 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
839 10 consecutive positions without losing lock. This ensures
840 that the GPS receiver has reliable reception from the
846 The Launchpad tab also shows the computed launch pad position
847 and altitude, averaging many reported positions to improve the
853 <title>Ascent</title>
855 This tab is shown during Boost, Fast and Coast
856 phases. The information displayed here helps monitor the
857 rocket as it heads towards apogee.
860 The height, speed and acceleration are shown along with the
861 maximum values for each of them. This allows you to quickly
862 answer the most commonly asked questions you'll hear during
866 The current latitude and longitude reported by the TeleMetrum GPS are
867 also shown. Note that under high acceleration, these values
868 may not get updated as the GPS receiver loses position
869 fix. Once the rocket starts coasting, the receiver should
870 start reporting position again.
873 Finally, the current igniter voltages are reported as in the
874 Launch Pad tab. This can help diagnose deployment failures
875 caused by wiring which comes loose under high acceleration.
879 <title>Descent</title>
881 Once the rocket has reached apogee and (we hope) activated the
882 apogee charge, attention switches to tracking the rocket on
883 the way back to the ground, and for dual-deploy flights,
884 waiting for the main charge to fire.
887 To monitor whether the apogee charge operated correctly, the
888 current descent rate is reported along with the current
889 height. Good descent rates vary based on the choice of recovery
890 components, but generally range from 15-30m/s on drogue and should
891 be below 10m/s when under the main parachute in a dual-deploy flight.
894 For TeleMetrum altimeters, you can locate the rocket in the
895 sky using the elevation and bearing information to figure
896 out where to look. Elevation is in degrees above the
897 horizon. Bearing is reported in degrees relative to true
898 north. Range can help figure out how big the rocket will
899 appear. Ground Distance shows how far it is to a point
900 directly under the rocket and can help figure out where the
901 rocket is likely to land. Note that all of these values are
902 relative to the pad location. If the elevation is near 90°,
903 the rocket is over the pad, not over you.
906 Finally, the igniter voltages are reported in this tab as
907 well, both to monitor the main charge as well as to see what
908 the status of the apogee charge is. Note that some commercial
909 e-matches are designed to retain continuity even after being
910 fired, and will continue to show as green or return from red to
915 <title>Landed</title>
917 Once the rocket is on the ground, attention switches to
918 recovery. While the radio signal is often lost once the
919 rocket is on the ground, the last reported GPS position is
920 generally within a short distance of the actual landing location.
923 The last reported GPS position is reported both by
924 latitude and longitude as well as a bearing and distance from
925 the launch pad. The distance should give you a good idea of
926 whether to walk or hitch a ride. Take the reported
927 latitude and longitude and enter them into your hand-held GPS
928 unit and have that compute a track to the landing location.
931 Both TeleMini and TeleMetrum will continue to transmit RDF
932 tones after landing, allowing you to locate the rocket by
933 following the radio signal if necessary. You may need to get
934 away from the clutter of the flight line, or even get up on
935 a hill (or your neighbor's RV roof) to receive the RDF signal.
938 The maximum height, speed and acceleration reported
939 during the flight are displayed for your admiring observers.
940 The accuracy of these immediate values depends on the quality
941 of your radio link and how many packets were received.
942 Recovering the on-board data after flight will likely yield
943 more precise results.
946 To get more detailed information about the flight, you can
947 click on the 'Graph Flight' button which will bring up a
948 graph window for the current flight.
952 <title>Site Map</title>
954 When the TeleMetrum has a GPS fix, the Site Map tab will map
955 the rocket's position to make it easier for you to locate the
956 rocket, both while it is in the air, and when it has landed. The
957 rocket's state is indicated by color: white for pad, red for
958 boost, pink for fast, yellow for coast, light blue for drogue,
959 dark blue for main, and black for landed.
962 The map's scale is approximately 3m (10ft) per pixel. The map
963 can be dragged using the left mouse button. The map will attempt
964 to keep the rocket roughly centered while data is being received.
967 Images are fetched automatically via the Google Maps Static API,
968 and cached on disk for reuse. If map images cannot be downloaded,
969 the rocket's path will be traced on a dark gray background
973 You can pre-load images for your favorite launch sites
974 before you leave home; check out the 'Preload Maps' section below.
979 <title>Save Flight Data</title>
981 The altimeter records flight data to its internal flash memory.
982 TeleMetrum data is recorded at a much higher rate than the telemetry
983 system can handle, and is not subject to radio drop-outs. As
984 such, it provides a more complete and precise record of the
985 flight. The 'Save Flight Data' button allows you to read the
986 flash memory and write it to disk. As TeleMini has only a barometer, it
987 records data at the same rate as the telemetry signal, but there will be
988 no data lost due to telemetry drop-outs.
991 Clicking on the 'Save Flight Data' button brings up a list of
992 connected TeleMetrum and TeleDongle devices. If you select a
993 TeleMetrum device, the flight data will be downloaded from that
994 device directly. If you select a TeleDongle device, flight data
995 will be downloaded from an altimeter over radio link via the
996 specified TeleDongle. See the chapter on Controlling An Altimeter
997 Over The Radio Link for more information.
1000 After the device has been selected, a dialog showing the
1001 flight data saved in the device will be shown allowing you to
1002 select which flights to download and which to delete. With
1003 version 0.9 or newer firmware, you must erase flights in order
1004 for the space they consume to be reused by another
1005 flight. This prevents accidentally losing flight data
1006 if you neglect to download data before flying again. Note that
1007 if there is no more space available in the device, then no
1008 data will be recorded during the next flight.
1011 The file name for each flight log is computed automatically
1012 from the recorded flight date, altimeter serial number and
1013 flight number information.
1017 <title>Replay Flight</title>
1019 Select this button and you are prompted to select a flight
1020 record file, either a .telem file recording telemetry data or a
1021 .eeprom file containing flight data saved from the altimeter
1025 Once a flight record is selected, the flight monitor interface
1026 is displayed and the flight is re-enacted in real time. Check
1027 the Monitor Flight chapter above to learn how this window operates.
1031 <title>Graph Data</title>
1033 Select this button and you are prompted to select a flight
1034 record file, either a .telem file recording telemetry data or a
1035 .eeprom file containing flight data saved from
1039 Once a flight record is selected, a window with two tabs is
1040 opened. The first tab contains a graph with acceleration
1041 (blue), velocity (green) and altitude (red) of the flight,
1042 measured in metric units. The
1043 apogee(yellow) and main(magenta) igniter voltages are also
1044 displayed; high voltages indicate continuity, low voltages
1045 indicate open circuits. The second tab contains some basic
1049 The graph can be zoomed into a particular area by clicking and
1050 dragging down and to the right. Once zoomed, the graph can be
1051 reset by clicking and dragging up and to the left. Holding down
1052 control and clicking and dragging allows the graph to be panned.
1053 The right mouse button causes a pop-up menu to be displayed, giving
1054 you the option save or print the plot.
1057 Note that telemetry files will generally produce poor graphs
1058 due to the lower sampling rate and missed telemetry packets.
1059 Use saved flight data in .eeprom files for graphing where possible.
1063 <title>Export Data</title>
1065 This tool takes the raw data files and makes them available for
1066 external analysis. When you select this button, you are prompted to
1068 data file (either .eeprom or .telem will do, remember that
1069 .eeprom files contain higher resolution and more continuous
1070 data). Next, a second dialog appears which is used to select
1071 where to write the resulting file. It has a selector to choose
1072 between CSV and KML file formats.
1075 <title>Comma Separated Value Format</title>
1077 This is a text file containing the data in a form suitable for
1078 import into a spreadsheet or other external data analysis
1079 tool. The first few lines of the file contain the version and
1080 configuration information from the altimeter, then
1081 there is a single header line which labels all of the
1082 fields. All of these lines start with a '#' character which
1083 many tools can be configured to skip over.
1086 The remaining lines of the file contain the data, with each
1087 field separated by a comma and at least one space. All of
1088 the sensor values are converted to standard units, with the
1089 barometric data reported in both pressure, altitude and
1090 height above pad units.
1094 <title>Keyhole Markup Language (for Google Earth)</title>
1096 This is the format used by Google Earth to provide an overlay
1097 within that application. With this, you can use Google Earth to
1098 see the whole flight path in 3D.
1103 <title>Configure Altimeter</title>
1105 Select this button and then select either a TeleMetrum or
1106 TeleDongle Device from the list provided. Selecting a TeleDongle
1107 device will use the radio link to configure a remote altimeter.
1110 The first few lines of the dialog provide information about the
1111 connected device, including the product name,
1112 software version and hardware serial number. Below that are the
1113 individual configuration entries.
1116 At the bottom of the dialog, there are four buttons:
1121 Save. This writes any changes to the
1122 configuration parameter block in flash memory. If you don't
1123 press this button, any changes you make will be lost.
1128 Reset. This resets the dialog to the most recently saved values,
1129 erasing any changes you have made.
1134 Reboot. This reboots the device. Use this to
1135 switch from idle to pad mode by rebooting once the rocket is
1136 oriented for flight, or to confirm changes you think you saved
1142 Close. This closes the dialog. Any unsaved changes will be
1148 The rest of the dialog contains the parameters to be configured.
1151 <title>Main Deploy Altitude</title>
1153 This sets the altitude (above the recorded pad altitude) at
1154 which the 'main' igniter will fire. The drop-down menu shows
1155 some common values, but you can edit the text directly and
1156 choose whatever you like. If the apogee charge fires below
1157 this altitude, then the main charge will fire two seconds
1158 after the apogee charge fires.
1162 <title>Apogee Delay</title>
1164 When flying redundant electronics, it's often important to
1165 ensure that multiple apogee charges don't fire at precisely
1166 the same time, as that can over pressurize the apogee deployment
1167 bay and cause a structural failure of the air-frame. The Apogee
1168 Delay parameter tells the flight computer to fire the apogee
1169 charge a certain number of seconds after apogee has been
1174 <title>Radio Frequency</title>
1176 This configures which of the configured frequencies to use for both
1177 telemetry and packet command mode. Note that if you set this
1178 value via packet command mode, you will have to reconfigure
1179 the TeleDongle frequency before you will be able to use packet
1184 <title>Radio Calibration</title>
1186 The radios in every Altus Metrum device are calibrated at the
1187 factory to ensure that they transmit and receive on the
1188 specified frequency. If you need to you can adjust the calibration
1189 by changing this value. Do not do this without understanding what
1190 the value means, read the appendix on calibration and/or the source
1191 code for more information. To change a TeleDongle's calibration,
1192 you must reprogram the unit completely.
1196 <title>Callsign</title>
1198 This sets the call sign included in each telemetry packet. Set this
1199 as needed to conform to your local radio regulations.
1203 <title>Maximum Flight Log Size</title>
1205 This sets the space (in kilobytes) allocated for each flight
1206 log. The available space will be divided into chunks of this
1207 size. A smaller value will allow more flights to be stored,
1208 a larger value will record data from longer flights.
1212 <title>Ignite Mode</title>
1214 TeleMetrum and TeleMini provide two igniter channels as they
1215 were originally designed as dual-deploy flight
1216 computers. This configuration parameter allows the two
1217 channels to be used in different configurations.
1222 Dual Deploy. This is the usual mode of operation; the
1223 'apogee' channel is fired at apogee and the 'main'
1224 channel at the height above ground specified by the
1225 'Main Deploy Altitude' during descent.
1230 Redundant Apogee. This fires both channels at
1231 apogee, the 'apogee' channel first followed after a two second
1232 delay by the 'main' channel.
1237 Redundant Main. This fires both channels at the
1238 height above ground specified by the Main Deploy
1239 Altitude setting during descent. The 'apogee'
1240 channel is fired first, followed after a two second
1241 delay by the 'main' channel.
1247 <title>Pad Orientation</title>
1249 Because it includes an accelerometer, TeleMetrum is
1250 sensitive to the orientation of the board. By default, it
1251 expects the antenna end to point forward. This parameter
1252 allows that default to be changed, permitting the board to
1253 be mounted with the antenna pointing aft instead.
1258 Antenna Up. In this mode, the antenna end of the
1259 TeleMetrum board must point forward, in line with the
1260 expected flight path.
1265 Antenna Down. In this mode, the antenna end of the
1266 TeleMetrum board must point aft, in line with the
1267 expected flight path.
1274 <title>Configure AltosUI</title>
1276 This button presents a dialog so that you can configure the AltosUI global settings.
1279 <title>Voice Settings</title>
1281 AltosUI provides voice announcements during flight so that you
1282 can keep your eyes on the sky and still get information about
1283 the current flight status. However, sometimes you don't want
1288 <para>Enable—turns all voice announcements on and off</para>
1292 Test Voice—Plays a short message allowing you to verify
1293 that the audio system is working and the volume settings
1300 <title>Log Directory</title>
1302 AltosUI logs all telemetry data and saves all TeleMetrum flash
1303 data to this directory. This directory is also used as the
1304 staring point when selecting data files for display or export.
1307 Click on the directory name to bring up a directory choosing
1308 dialog, select a new directory and click 'Select Directory' to
1309 change where AltosUI reads and writes data files.
1313 <title>Callsign</title>
1315 This value is transmitted in each command packet sent from
1316 TeleDongle and received from an altimeter. It is not used in
1317 telemetry mode, as the callsign configured in the altimeter board
1318 is included in all telemetry packets. Configure this
1319 with the AltosUI operators call sign as needed to comply with
1320 your local radio regulations.
1324 <title>Imperial Units</title>
1326 This switches between metric units (meters) and imperial
1327 units (feet and miles). This affects the display of values
1328 use during flight monitoring, data graphing and all of the
1329 voice announcements. It does not change the units used when
1330 exporting to CSV files, those are always produced in metric units.
1334 <title>Font Size</title>
1336 Selects the set of fonts used in the flight monitor
1337 window. Choose between the small, medium and large sets.
1341 <title>Serial Debug</title>
1343 This causes all communication with a connected device to be
1344 dumped to the console from which AltosUI was started. If
1345 you've started it from an icon or menu entry, the output
1346 will simply be discarded. This mode can be useful to debug
1347 various serial communication issues.
1351 <title>Manage Frequencies</title>
1353 This brings up a dialog where you can configure the set of
1354 frequencies shown in the various frequency menus. You can
1355 add as many as you like, or even reconfigure the default
1356 set. Changing this list does not affect the frequency
1357 settings of any devices, it only changes the set of
1358 frequencies shown in the menus.
1363 <title>Configure Groundstation</title>
1365 Select this button and then select a TeleDongle Device from the list provided.
1368 The first few lines of the dialog provide information about the
1369 connected device, including the product name,
1370 software version and hardware serial number. Below that are the
1371 individual configuration entries.
1374 Note that the TeleDongle itself doesn't save any configuration
1375 data, the settings here are recorded on the local machine in
1376 the Java preferences database. Moving the TeleDongle to
1377 another machine, or using a different user account on the same
1378 machine will cause settings made here to have no effect.
1381 At the bottom of the dialog, there are three buttons:
1386 Save. This writes any changes to the
1387 local Java preferences file. If you don't
1388 press this button, any changes you make will be lost.
1393 Reset. This resets the dialog to the most recently saved values,
1394 erasing any changes you have made.
1399 Close. This closes the dialog. Any unsaved changes will be
1405 The rest of the dialog contains the parameters to be configured.
1408 <title>Frequency</title>
1410 This configures the frequency to use for both telemetry and
1411 packet command mode. Set this before starting any operation
1412 involving packet command mode so that it will use the right
1413 frequency. Telemetry monitoring mode also provides a menu to
1414 change the frequency, and that menu also sets the same Java
1415 preference value used here.
1419 <title>Radio Calibration</title>
1421 The radios in every Altus Metrum device are calibrated at the
1422 factory to ensure that they transmit and receive on the
1423 specified frequency. To change a TeleDongle's calibration,
1424 you must reprogram the unit completely, so this entry simply
1425 shows the current value and doesn't allow any changes.
1430 <title>Flash Image</title>
1432 This reprograms any Altus Metrum device by using a TeleMetrum
1433 or TeleDongle as a programming dongle. Please read the
1434 directions for flashing devices in the Updating Device
1435 Firmware chapter below.
1438 Once you have the programmer and target devices connected,
1439 push the 'Flash Image' button. That will present a dialog box
1440 listing all of the connected devices. Carefully select the
1441 programmer device, not the device to be programmed.
1444 Next, select the image to flash to the device. These are named
1445 with the product name and firmware version. The file selector
1446 will start in the directory containing the firmware included
1447 with the AltosUI package. Navigate to the directory containing
1448 the desired firmware if it isn't there.
1451 Next, a small dialog containing the device serial number and
1452 RF calibration values should appear. If these values are
1453 incorrect (possibly due to a corrupted image in the device),
1454 enter the correct values here.
1457 Finally, a dialog containing a progress bar will follow the
1458 programming process.
1461 When programming is complete, the target device will
1462 reboot. Note that if the target device is connected via USB, you
1463 will have to unplug it and then plug it back in for the USB
1464 connection to reset so that you can communicate with the device
1469 <title>Fire Igniter</title>
1471 This activates the igniter circuits in TeleMetrum to help test
1472 recovery systems deployment. Because this command can operate
1473 over the Packet Command Link, you can prepare the rocket as
1474 for flight and then test the recovery system without needing
1475 to snake wires inside the air-frame.
1478 Selecting the 'Fire Igniter' button brings up the usual device
1479 selection dialog. Pick the desired TeleDongle or TeleMetrum
1480 device. This brings up another window which shows the current
1481 continuity test status for both apogee and main charges.
1484 Next, select the desired igniter to fire. This will enable the
1488 Select the 'Arm' button. This enables the 'Fire' button. The
1489 word 'Arm' is replaced by a countdown timer indicating that
1490 you have 10 seconds to press the 'Fire' button or the system
1491 will deactivate, at which point you start over again at
1492 selecting the desired igniter.
1496 <title>Scan Channels</title>
1498 This listens for telemetry packets on all of the configured
1499 frequencies, displaying information about each device it
1500 receives a packet from. You can select which of the three
1501 telemetry formats should be tried; by default, it only listens
1502 for the standard telemetry packets used in v1.0 and later
1507 <title>Load Maps</title>
1509 Before heading out to a new launch site, you can use this to
1510 load satellite images in case you don't have internet
1511 connectivity at the site. This loads a fairly large area
1512 around the launch site, which should cover any flight you're likely to make.
1515 There's a drop-down menu of launch sites we know about; if
1516 your favorites aren't there, please let us know the lat/lon
1517 and name of the site. The contents of this list are actually
1518 downloaded at run-time, so as new sites are sent in, they'll
1519 get automatically added to this list.
1522 If the launch site isn't in the list, you can manually enter the lat/lon values
1525 Clicking the 'Load Map' button will fetch images from Google
1526 Maps; note that Google limits how many images you can fetch at
1527 once, so if you load more than one launch site, you may get
1528 some gray areas in the map which indicate that Google is tired
1529 of sending data to you. Try again later.
1533 <title>Monitor Idle</title>
1535 This brings up a dialog similar to the Monitor Flight UI,
1536 except it works with the altimeter in "idle" mode by sending
1537 query commands to discover the current state rather than
1538 listening for telemetry packets.
1543 <title>Using Altus Metrum Products</title>
1545 <title>Being Legal</title>
1547 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
1548 other authorization to legally operate the radio transmitters that are part
1553 <title>In the Rocket</title>
1555 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
1556 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
1557 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
1558 850mAh battery weighs less than a 9V alkaline battery, and will
1559 run a TeleMetrum for hours.
1560 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
1561 a few hours, or a TeleMini for much (much) longer.
1564 By default, we ship the altimeters with a simple wire antenna. If your
1565 electronics bay or the air-frame it resides within is made of carbon fiber,
1566 which is opaque to RF signals, you may choose to have an SMA connector
1567 installed so that you can run a coaxial cable to an antenna mounted
1568 elsewhere in the rocket.
1572 <title>On the Ground</title>
1574 To receive the data stream from the rocket, you need an antenna and short
1575 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. The
1576 TeleDongle in turn plugs directly into the USB port on a notebook
1577 computer. Because TeleDongle looks like a simple serial port, your computer
1578 does not require special device drivers... just plug it in.
1581 The GUI tool, AltosUI, is written in Java and runs across
1582 Linux, Mac OS and Windows. There's also a suite of C tools
1583 for Linux which can perform most of the same tasks.
1586 After the flight, you can use the radio link to extract the more detailed data
1587 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
1588 TeleMetrum board directly. Pulling out the data without having to open up
1589 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
1590 battery, so you'll want one of those anyway... the same cable used by lots
1591 of digital cameras and other modern electronic stuff will work fine.
1594 If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
1595 receiver, so that you can put in a way-point for the last reported rocket
1596 position before touch-down. This makes looking for your rocket a lot like
1597 Geo-Caching... just go to the way-point and look around starting from there.
1600 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
1601 can use that with your antenna to direction-find the rocket on the ground
1602 the same way you can use a Walston or Beeline tracker. This can be handy
1603 if the rocket is hiding in sage brush or a tree, or if the last GPS position
1604 doesn't get you close enough because the rocket dropped into a canyon, or
1605 the wind is blowing it across a dry lake bed, or something like that... Keith
1606 and Bdale both currently own and use the Yaesu VX-7R at launches.
1609 So, to recap, on the ground the hardware you'll need includes:
1610 <orderedlist inheritnum='inherit' numeration='arabic'>
1612 an antenna and feed-line
1621 optionally, a hand-held GPS receiver
1624 optionally, an HT or receiver covering 435 MHz
1629 The best hand-held commercial directional antennas we've found for radio
1630 direction finding rockets are from
1631 <ulink url="http://www.arrowantennas.com/" >
1634 The 440-3 and 440-5 are both good choices for finding a
1635 TeleMetrum- or TeleMini- equipped rocket when used with a suitable 70cm HT.
1639 <title>Data Analysis</title>
1641 Our software makes it easy to log the data from each flight, both the
1642 telemetry received during the flight itself, and the more
1643 complete data log recorded in the flash memory on the altimeter
1644 board. Once this data is on your computer, our post-flight tools make it
1645 easy to quickly get to the numbers everyone wants, like apogee altitude,
1646 max acceleration, and max velocity. You can also generate and view a
1647 standard set of plots showing the altitude, acceleration, and
1648 velocity of the rocket during flight. And you can even export a TeleMetrum data file
1649 usable with Google Maps and Google Earth for visualizing the flight path
1650 in two or three dimensions!
1653 Our ultimate goal is to emit a set of files for each flight that can be
1654 published as a web page per flight, or just viewed on your local disk with
1659 <title>Future Plans</title>
1661 In the future, we intend to offer "companion boards" for the rocket that will
1662 plug in to TeleMetrum to collect additional data, provide more pyro channels,
1666 We are also working on the design of a hand-held ground terminal that will
1667 allow monitoring the rocket's status, collecting data during flight, and
1668 logging data after flight without the need for a notebook computer on the
1669 flight line. Particularly since it is so difficult to read most notebook
1670 screens in direct sunlight, we think this will be a great thing to have.
1673 Because all of our work is open, both the hardware designs and the software,
1674 if you have some great idea for an addition to the current Altus Metrum family,
1675 feel free to dive in and help! Or let us know what you'd like to see that
1676 we aren't already working on, and maybe we'll get excited about it too...
1681 <title>Altimeter Installation Recommendations</title>
1683 Building high-power rockets that fly safely is hard enough. Mix
1684 in some sophisticated electronics and a bunch of radio energy
1685 and oftentimes you find few perfect solutions. This chapter
1686 contains some suggestions about how to install Altus Metrum
1687 products into the rocket air-frame, including how to safely and
1688 reliably mix a variety of electronics into the same air-frame.
1691 <title>Mounting the Altimeter</title>
1693 The first consideration is to ensure that the altimeter is
1694 securely fastened to the air-frame. For TeleMetrum, we use
1695 nylon standoffs and nylon screws; they're good to at least 50G
1696 and cannot cause any electrical issues on the board. For
1697 TeleMini, we usually cut small pieces of 1/16" balsa to fit
1698 under the screw holes, and then take 2x56 nylon screws and
1699 screw them through the TeleMini mounting holes, through the
1700 balsa and into the underlying material.
1702 <orderedlist inheritnum='inherit' numeration='arabic'>
1704 Make sure TeleMetrum is aligned precisely along the axis of
1705 acceleration so that the accelerometer can accurately
1706 capture data during the flight.
1709 Watch for any metal touching components on the
1710 board. Shorting out connections on the bottom of the board
1711 can cause the altimeter to fail during flight.
1716 <title>Dealing with the Antenna</title>
1718 The antenna supplied is just a piece of solid, insulated,
1719 wire. If it gets damaged or broken, it can be easily
1720 replaced. It should be kept straight and not cut; bending or
1721 cutting it will change the resonant frequency and/or
1722 impedance, making it a less efficient radiator and thus
1723 reducing the range of the telemetry signal.
1726 Keeping metal away from the antenna will provide better range
1727 and a more even radiation pattern. In most rockets, it's not
1728 entirely possible to isolate the antenna from metal
1729 components; there are often bolts, all-thread and wires from other
1730 electronics to contend with. Just be aware that the more stuff
1731 like this around the antenna, the lower the range.
1734 Make sure the antenna is not inside a tube made or covered
1735 with conducting material. Carbon fiber is the most common
1736 culprit here -- CF is a good conductor and will effectively
1737 shield the antenna, dramatically reducing signal strength and
1738 range. Metallic flake paint is another effective shielding
1739 material which is to be avoided around any antennas.
1742 If the ebay is large enough, it can be convenient to simply
1743 mount the altimeter at one end and stretch the antenna out
1744 inside. Taping the antenna to the sled can keep it straight
1745 under acceleration. If there are metal rods, keep the
1746 antenna as far away as possible.
1749 For a shorter ebay, it's quite practical to have the antenna
1750 run through a bulkhead and into an adjacent bay. Drill a small
1751 hole in the bulkhead, pass the antenna wire through it and
1752 then seal it up with glue or clay. We've also used acrylic
1753 tubing to create a cavity for the antenna wire. This works a
1754 bit better in that the antenna is known to stay straight and
1755 not get folded by recovery components in the bay. Angle the
1756 tubing towards the side wall of the rocket and it ends up
1757 consuming very little space.
1760 If you need to place the antenna at a distance from the
1761 altimeter, you can replace the antenna with an edge-mounted
1762 SMA connector, and then run 50Ω coax from the board to the
1763 antenna. Building a remote antenna is beyond the scope of this
1768 <title>Preserving GPS Reception</title>
1770 The GPS antenna and receiver in TeleMetrum are highly
1771 sensitive and normally have no trouble tracking enough
1772 satellites to provide accurate position information for
1773 recovering the rocket. However, there are many ways to
1774 attenuate the GPS signal.
1775 <orderedlist inheritnum='inherit' numeration='arabic'>
1777 Conductive tubing or coatings. Carbon fiber and metal
1778 tubing, or metallic paint will all dramatically attenuate the
1779 GPS signal. We've never heard of anyone successfully
1780 receiving GPS from inside these materials.
1783 Metal components near the GPS patch antenna. These will
1784 de-tune the patch antenna, changing the resonant frequency
1785 away from the L1 carrier and reduce the effectiveness of the
1786 antenna. You can place as much stuff as you like beneath the
1787 antenna as that's covered with a ground plane. But, keep
1788 wires and metal out from above the patch antenna.
1794 <title>Radio Frequency Interference</title>
1796 Any altimeter will generate RFI; the digital circuits use
1797 high-frequency clocks that spray radio interference across a
1798 wide band. Altus Metrum altimeters generate intentional radio
1799 signals as well, increasing the amount of RF energy around the board.
1802 Rocketry altimeters also use precise sensors measuring air
1803 pressure and acceleration. Tiny changes in voltage can cause
1804 these sensor readings to vary by a huge amount. When the
1805 sensors start mis-reporting data, the altimeter can either
1806 fire the igniters at the wrong time, or not fire them at all.
1809 Voltages are induced when radio frequency energy is
1810 transmitted from one circuit to another. Here are things that
1811 influence the induced voltage and current:
1815 Keep wires from different circuits apart. Moving circuits
1816 further apart will reduce RFI.
1819 Avoid parallel wires from different circuits. The longer two
1820 wires run parallel to one another, the larger the amount of
1821 transferred energy. Cross wires at right angles to reduce
1825 Twist wires from the same circuits. Two wires the same
1826 distance from the transmitter will get the same amount of
1827 induced energy which will then cancel out. Any time you have
1828 a wire pair running together, twist the pair together to
1829 even out distances and reduce RFI. For altimeters, this
1830 includes battery leads, switch hookups and igniter
1834 Avoid resonant lengths. Know what frequencies are present
1835 in the environment and avoid having wire lengths near a
1836 natural resonant length. Altusmetrum products transmit on the
1837 70cm amateur band, so you should avoid lengths that are a
1838 simple ratio of that length; essentially any multiple of 1/4
1839 of the wavelength (17.5cm).
1844 <title>The Barometric Sensor</title>
1846 Altusmetrum altimeters measure altitude with a barometric
1847 sensor, essentially measuring the amount of air above the
1848 rocket to figure out how high it is. A large number of
1849 measurements are taken as the altimeter initializes itself to
1850 figure out the pad altitude. Subsequent measurements are then
1851 used to compute the height above the pad.
1854 To accurately measure atmospheric pressure, the ebay
1855 containing the altimeter must be vented outside the
1856 air-frame. The vent must be placed in a region of linear
1857 airflow, have smooth edges, and away from areas of increasing or
1858 decreasing pressure.
1861 The barometric sensor in the altimeter is quite sensitive to
1862 chemical damage from the products of APCP or BP combustion, so
1863 make sure the ebay is carefully sealed from any compartment
1864 which contains ejection charges or motors.
1868 <title>Ground Testing</title>
1870 The most important aspect of any installation is careful
1871 ground testing. Bringing an air-frame up to the LCO table which
1872 hasn't been ground tested can lead to delays or ejection
1873 charges firing on the pad, or, even worse, a recovery system
1877 Do a 'full systems' test that includes wiring up all igniters
1878 without any BP and turning on all of the electronics in flight
1879 mode. This will catch any mistakes in wiring and any residual
1880 RFI issues that might accidentally fire igniters at the wrong
1881 time. Let the air-frame sit for several minutes, checking for
1882 adequate telemetry signal strength and GPS lock. If any igniters
1883 fire unexpectedly, find and resolve the issue before loading any
1887 Ground test the ejection charges. Prepare the rocket for
1888 flight, loading ejection charges and igniters. Completely
1889 assemble the air-frame and then use the 'Fire Igniters'
1890 interface through a TeleDongle to command each charge to
1891 fire. Make sure the charge is sufficient to robustly separate
1892 the air-frame and deploy the recovery system.
1897 <title>Updating Device Firmware</title>
1899 The big concept to understand is that you have to use a
1900 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
1901 and a TeleMetrum or other TeleDongle to program the TeleDongle
1902 Due to limited memory resources in the cc1111, we don't support
1903 programming directly over USB.
1906 You may wish to begin by ensuring you have current firmware images.
1907 These are distributed as part of the AltOS software bundle that
1908 also includes the AltosUI ground station program. Newer ground
1909 station versions typically work fine with older firmware versions,
1910 so you don't need to update your devices just to try out new
1911 software features. You can always download the most recent
1912 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
1915 We recommend updating the altimeter first, before updating TeleDongle.
1918 <title>Updating TeleMetrum Firmware</title>
1919 <orderedlist inheritnum='inherit' numeration='arabic'>
1921 Find the 'programming cable' that you got as part of the starter
1922 kit, that has a red 8-pin MicroMaTch connector on one end and a
1923 red 4-pin MicroMaTch connector on the other end.
1926 Take the 2 screws out of the TeleDongle case to get access
1927 to the circuit board.
1930 Plug the 8-pin end of the programming cable to the
1931 matching connector on the TeleDongle, and the 4-pin end to the
1932 matching connector on the TeleMetrum.
1933 Note that each MicroMaTch connector has an alignment pin that
1934 goes through a hole in the PC board when you have the cable
1938 Attach a battery to the TeleMetrum board.
1941 Plug the TeleDongle into your computer's USB port, and power
1945 Run AltosUI, and select 'Flash Image' from the File menu.
1948 Pick the TeleDongle device from the list, identifying it as the
1952 Select the image you want put on the TeleMetrum, which should have a
1953 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
1954 in the default directory, if not you may have to poke around
1955 your system to find it.
1958 Make sure the configuration parameters are reasonable
1959 looking. If the serial number and/or RF configuration
1960 values aren't right, you'll need to change them.
1963 Hit the 'OK' button and the software should proceed to flash
1964 the TeleMetrum with new firmware, showing a progress bar.
1967 Confirm that the TeleMetrum board seems to have updated OK, which you
1968 can do by plugging in to it over USB and using a terminal program
1969 to connect to the board and issue the 'v' command to check
1973 If something goes wrong, give it another try.
1978 <title>Updating TeleMini Firmware</title>
1979 <orderedlist inheritnum='inherit' numeration='arabic'>
1981 You'll need a special 'programming cable' to reprogram the
1982 TeleMini. It's available on the Altus Metrum web store, or
1983 you can make your own using an 8-pin MicroMaTch connector on
1984 one end and a set of four pins on the other.
1987 Take the 2 screws out of the TeleDongle case to get access
1988 to the circuit board.
1991 Plug the 8-pin end of the programming cable to the matching
1992 connector on the TeleDongle, and the 4-pins into the holes
1993 in the TeleMini circuit board. Note that the MicroMaTch
1994 connector has an alignment pin that goes through a hole in
1995 the PC board when you have the cable oriented correctly, and
1996 that pin 1 on the TeleMini board is marked with a square pad
1997 while the other pins have round pads.
2000 Attach a battery to the TeleMini board.
2003 Plug the TeleDongle into your computer's USB port, and power
2007 Run AltosUI, and select 'Flash Image' from the File menu.
2010 Pick the TeleDongle device from the list, identifying it as the
2014 Select the image you want put on the TeleMini, which should have a
2015 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
2016 in the default directory, if not you may have to poke around
2017 your system to find it.
2020 Make sure the configuration parameters are reasonable
2021 looking. If the serial number and/or RF configuration
2022 values aren't right, you'll need to change them.
2025 Hit the 'OK' button and the software should proceed to flash
2026 the TeleMini with new firmware, showing a progress bar.
2029 Confirm that the TeleMini board seems to have updated OK, which you
2030 can do by configuring it over the radio link through the TeleDongle, or
2031 letting it come up in "flight" mode and listening for telemetry.
2034 If something goes wrong, give it another try.
2039 <title>Updating TeleDongle Firmware</title>
2041 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
2042 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
2044 <orderedlist inheritnum='inherit' numeration='arabic'>
2046 Find the 'programming cable' that you got as part of the starter
2047 kit, that has a red 8-pin MicroMaTch connector on one end and a
2048 red 4-pin MicroMaTch connector on the other end.
2051 Find the USB cable that you got as part of the starter kit, and
2052 plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
2055 Take the 2 screws out of the TeleDongle case to get access
2056 to the circuit board.
2059 Plug the 8-pin end of the programming cable to the
2060 matching connector on the programmer, and the 4-pin end to the
2061 matching connector on the TeleDongle.
2062 Note that each MicroMaTch connector has an alignment pin that
2063 goes through a hole in the PC board when you have the cable
2067 Attach a battery to the TeleMetrum board if you're using one.
2070 Plug both the programmer and the TeleDongle into your computer's USB
2071 ports, and power up the programmer.
2074 Run AltosUI, and select 'Flash Image' from the File menu.
2077 Pick the programmer device from the list, identifying it as the
2081 Select the image you want put on the TeleDongle, which should have a
2082 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
2083 in the default directory, if not you may have to poke around
2084 your system to find it.
2087 Make sure the configuration parameters are reasonable
2088 looking. If the serial number and/or RF configuration
2089 values aren't right, you'll need to change them. The TeleDongle
2090 serial number is on the "bottom" of the circuit board, and can
2091 usually be read through the translucent blue plastic case without
2092 needing to remove the board from the case.
2095 Hit the 'OK' button and the software should proceed to flash
2096 the TeleDongle with new firmware, showing a progress bar.
2099 Confirm that the TeleDongle board seems to have updated OK, which you
2100 can do by plugging in to it over USB and using a terminal program
2101 to connect to the board and issue the 'v' command to check
2102 the version, etc. Once you're happy, remove the programming cable
2103 and put the cover back on the TeleDongle.
2106 If something goes wrong, give it another try.
2110 Be careful removing the programming cable from the locking 8-pin
2111 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
2112 screwdriver or knife blade to gently pry the locking ears out
2113 slightly to extract the connector. We used a locking connector on
2114 TeleMetrum to help ensure that the cabling to companion boards
2115 used in a rocket don't ever come loose accidentally in flight.
2120 <title>Hardware Specifications</title>
2122 <title>TeleMetrum Specifications</title>
2126 Recording altimeter for model rocketry.
2131 Supports dual deployment (can fire 2 ejection charges).
2136 70cm ham-band transceiver for telemetry down-link.
2141 Barometric pressure sensor good to 45k feet MSL.
2146 1-axis high-g accelerometer for motor characterization, capable of
2147 +/- 50g using default part.
2152 On-board, integrated GPS receiver with 5Hz update rate capability.
2157 On-board 1 megabyte non-volatile memory for flight data storage.
2162 USB interface for battery charging, configuration, and data recovery.
2167 Fully integrated support for Li-Po rechargeable batteries.
2172 Uses Li-Po to fire e-matches, can be modified to support
2173 optional separate pyro battery if needed.
2178 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
2184 <title>TeleMini Specifications</title>
2188 Recording altimeter for model rocketry.
2193 Supports dual deployment (can fire 2 ejection charges).
2198 70cm ham-band transceiver for telemetry down-link.
2203 Barometric pressure sensor good to 45k feet MSL.
2208 On-board 5 kilobyte non-volatile memory for flight data storage.
2213 RF interface for configuration, and data recovery.
2218 Support for Li-Po rechargeable batteries, using an external charger.
2223 Uses Li-Po to fire e-matches, can be modified to support
2224 optional separate pyro battery if needed.
2229 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
2238 TeleMetrum seems to shut off when disconnected from the
2239 computer. Make sure the battery is adequately charged. Remember the
2240 unit will pull more power than the USB port can deliver before the
2241 GPS enters "locked" mode. The battery charges best when TeleMetrum
2245 It's impossible to stop the TeleDongle when it's in "p" mode, I have
2246 to unplug the USB cable? Make sure you have tried to "escape out" of
2247 this mode. If this doesn't work the reboot procedure for the
2248 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
2249 outgoing buffer IF your "escape out" ('~~') does not work.
2250 At this point using either 'ao-view' (or possibly
2251 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
2255 The amber LED (on the TeleMetrum) lights up when both
2256 battery and USB are connected. Does this mean it's charging?
2257 Yes, the yellow LED indicates the charging at the 'regular' rate.
2258 If the led is out but the unit is still plugged into a USB port,
2259 then the battery is being charged at a 'trickle' rate.
2262 There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
2263 That's the "pad" mode. Weak batteries might be the problem.
2264 It is also possible that the TeleMetrum is horizontal and the output
2265 is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
2266 it received a command packet which would have left it in "pad" mode.
2269 How do I save flight data?
2270 Live telemetry is written to file(s) whenever AltosUI is connected
2271 to the TeleDongle. The file area defaults to ~/TeleMetrum
2272 but is easily changed using the menus in AltosUI. The files that
2273 are written end in '.telem'. The after-flight
2274 data-dumped files will end in .eeprom and represent continuous data
2275 unlike the .telem files that are subject to losses
2276 along the RF data path.
2277 See the above instructions on what and how to save the eeprom stored
2278 data after physically retrieving your altimeter. Make sure to save
2279 the on-board data after each flight; while the TeleMetrum can store
2280 multiple flights, you never know when you'll lose the altimeter...
2284 <title>Notes for Older Software</title>
2287 Before AltosUI was written, using Altus Metrum devices required
2288 some finesse with the Linux command line. There was a limited
2289 GUI tool, ao-view, which provided functionality similar to the
2290 Monitor Flight window in AltosUI, but everything else was a
2291 fairly 80's experience. This appendix includes documentation for
2292 using that software.
2296 Both TeleMetrum and TeleDongle can be directly communicated
2297 with using USB ports. The first thing you should try after getting
2298 both units plugged into to your computer's USB port(s) is to run
2299 'ao-list' from a terminal-window to see what port-device-name each
2300 device has been assigned by the operating system.
2301 You will need this information to access the devices via their
2302 respective on-board firmware and data using other command line
2303 programs in the AltOS software suite.
2306 TeleMini can be communicated with through a TeleDongle device
2307 over the radio link. When first booted, TeleMini listens for a
2308 TeleDongle device and if it receives a packet, it goes into
2309 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
2310 launched. The easiest way to get it talking is to start the
2311 communication link on the TeleDongle and the power up the
2315 To access the device's firmware for configuration you need a terminal
2316 program such as you would use to talk to a modem. The software
2317 authors prefer using the program 'cu' which comes from the UUCP package
2318 on most Unix-like systems such as Linux. An example command line for
2319 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
2320 indicated from running the
2321 ao-list program. Another reasonable terminal program for Linux is
2322 'cutecom'. The default 'escape'
2323 character used by CU (i.e. the character you use to
2324 issue commands to cu itself instead of sending the command as input
2325 to the connected device) is a '~'. You will need this for use in
2326 only two different ways during normal operations. First is to exit
2327 the program by sending a '~.' which is called a 'escape-disconnect'
2328 and allows you to close-out from 'cu'. The
2329 second use will be outlined later.
2332 All of the Altus Metrum devices share the concept of a two level
2333 command set in their firmware.
2334 The first layer has several single letter commands. Once
2335 you are using 'cu' (or 'cutecom') sending (typing) a '?'
2336 returns a full list of these
2337 commands. The second level are configuration sub-commands accessed
2338 using the 'c' command, for
2339 instance typing 'c?' will give you this second level of commands
2340 (all of which require the
2341 letter 'c' to access). Please note that most configuration options
2342 are stored only in Flash memory; TeleDongle doesn't provide any storage
2343 for these options and so they'll all be lost when you unplug it.
2346 Try setting these configuration ('c' or second level menu) values. A good
2347 place to start is by setting your call sign. By default, the boards
2348 use 'N0CALL' which is cute, but not exactly legal!
2349 Spend a few minutes getting comfortable with the units, their
2350 firmware, and 'cu' (or possibly 'cutecom').
2351 For instance, try to send
2352 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
2353 Verify you can connect and disconnect from the units while in your
2354 terminal program by sending the escape-disconnect mentioned above.
2357 To set the radio frequency, use the 'c R' command to specify the
2358 radio transceiver configuration parameter. This parameter is computed
2359 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
2360 the standard calibration reference frequency, 'S', (normally 434.550MHz):
2364 Round the result to the nearest integer value.
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 flash on
2367 your altimeter board if you want the change to stay in place across reboots.
2370 To set the apogee delay, use the 'c d' command.
2371 As with all 'c' sub-commands, follow this with a 'c w' to write the
2372 change to the parameter block in the on-board DataFlash chip.
2375 To set the main deployment altitude, use the 'c m' command.
2376 As with all 'c' sub-commands, follow this with a 'c w' to write the
2377 change to the parameter block in the on-board DataFlash chip.
2380 To calibrate the radio frequency, connect the UHF antenna port to a
2381 frequency counter, set the board to 434.550MHz, and use the 'C'
2382 command to generate a CW carrier. Wait for the transmitter temperature
2383 to stabilize and the frequency to settle down.
2384 Then, divide 434.550 MHz by the
2385 measured frequency and multiply by the current radio cal value show
2386 in the 'c s' command. For an unprogrammed board, the default value
2387 is 1186611. Take the resulting integer and program it using the 'c f'
2388 command. Testing with the 'C' command again should show a carrier
2389 within a few tens of Hertz of the intended frequency.
2390 As with all 'c' sub-commands, follow this with a 'c w' to write the
2391 change to the parameter block in the on-board DataFlash chip.
2394 Note that the 'reboot' command, which is very useful on the altimeters,
2395 will likely just cause problems with the dongle. The *correct* way
2396 to reset the dongle is just to unplug and re-plug it.
2399 A fun thing to do at the launch site and something you can do while
2400 learning how to use these units is to play with the radio link access
2401 between an altimeter and the TeleDongle. Be aware that you *must* create
2402 some physical separation between the devices, otherwise the link will
2403 not function due to signal overload in the receivers in each device.
2406 Now might be a good time to take a break and read the rest of this
2407 manual, particularly about the two "modes" that the altimeters
2408 can be placed in. TeleMetrum uses the position of the device when booting
2409 up will determine whether the unit is in "pad" or "idle" mode. TeleMini
2410 enters "idle" mode when it receives a command packet within the first 5 seconds
2411 of being powered up, otherwise it enters "pad" mode.
2414 You can access an altimeter in idle mode from the TeleDongle's USB
2415 connection using the radio link
2416 by issuing a 'p' command to the TeleDongle. Practice connecting and
2417 disconnecting ('~~' while using 'cu') from the altimeter. If
2418 you cannot escape out of the "p" command, (by using a '~~' when in
2419 CU) then it is likely that your kernel has issues. Try a newer version.
2422 Using this radio link allows you to configure the altimeter, test
2423 fire e-matches and igniters from the flight line, check pyro-match
2424 continuity and so forth. You can leave the unit turned on while it
2425 is in 'idle mode' and then place the
2426 rocket vertically on the launch pad, walk away and then issue a
2427 reboot command. The altimeter will reboot and start sending data
2428 having changed to the "pad" mode. If the TeleDongle is not receiving
2429 this data, you can disconnect 'cu' from the TeleDongle using the
2430 procedures mentioned above and THEN connect to the TeleDongle from
2431 inside 'ao-view'. If this doesn't work, disconnect from the
2432 TeleDongle, unplug it, and try again after plugging it back in.
2435 In order to reduce the chance of accidental firing of pyrotechnic
2436 charges, the command to fire a charge is intentionally somewhat
2437 difficult to type, and the built-in help is slightly cryptic to
2438 prevent accidental echoing of characters from the help text back at
2439 the board from firing a charge. The command to fire the apogee
2440 drogue charge is 'i DoIt drogue' and the command to fire the main
2441 charge is 'i DoIt main'.
2444 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
2445 and 'ao-view' will both auditorily announce and visually indicate
2447 Now you can launch knowing that you have a good data path and
2448 good satellite lock for flight data and recovery. Remember
2449 you MUST tell ao-view to connect to the TeleDongle explicitly in
2450 order for ao-view to be able to receive data.
2453 The altimeters provide RDF (radio direction finding) tones on
2454 the pad, during descent and after landing. These can be used to
2455 locate the rocket using a directional antenna; the signal
2456 strength providing an indication of the direction from receiver to rocket.
2459 TeleMetrum also provides GPS tracking data, which can further simplify
2460 locating the rocket once it has landed. (The last good GPS data
2461 received before touch-down will be on the data screen of 'ao-view'.)
2464 Once you have recovered the rocket you can download the eeprom
2465 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
2466 either a USB cable or over the radio link using TeleDongle.
2467 And by following the man page for 'ao-postflight' you can create
2468 various data output reports, graphs, and even KML data to see the
2469 flight trajectory in Google-earth. (Moving the viewing angle making
2470 sure to connect the yellow lines while in Google-earth is the proper
2474 As for ao-view.... some things are in the menu but don't do anything
2475 very useful. The developers have stopped working on ao-view to focus
2476 on a new, cross-platform ground station program. So ao-view may or
2477 may not be updated in the future. Mostly you just use
2478 the Log and Device menus. It has a wonderful display of the incoming
2479 flight data and I am sure you will enjoy what it has to say to you
2480 once you enable the voice output!
2484 <title>Calibration</title>
2486 There are only two calibrations required for a TeleMetrum board, and
2487 only one for TeleDongle and TeleMini. All boards are shipped from
2488 the factory pre-calibrated, but the procedures are documented here
2489 in case they are ever needed. Re-calibration is not supported by
2490 AltosUI, you must connect to the board with a serial terminal program
2491 and interact directly with the on-board command interpreter to effect
2495 <title>Radio Frequency</title>
2497 The radio frequency is synthesized from a clock based on the 48 MHz
2498 crystal on the board. The actual frequency of this oscillator
2499 must be measured to generate a calibration constant. While our
2501 bandwidth is wide enough to allow boards to communicate even when
2502 their oscillators are not on exactly the same frequency, performance
2503 is best when they are closely matched.
2504 Radio frequency calibration requires a calibrated frequency counter.
2505 Fortunately, once set, the variation in frequency due to aging and
2506 temperature changes is small enough that re-calibration by customers
2507 should generally not be required.
2510 To calibrate the radio frequency, connect the UHF antenna port to a
2511 frequency counter, set the board to 434.550MHz, and use the 'C'
2512 command in the on-board command interpreter to generate a CW
2513 carrier. For TeleMetrum, this is best done over USB. For TeleMini,
2514 note that the only way to escape the 'C' command is via power cycle
2515 since the board will no longer be listening for commands once it
2516 starts generating a CW carrier.
2519 Wait for the transmitter temperature to stabilize and the frequency
2520 to settle down. Then, divide 434.550 MHz by the
2521 measured frequency and multiply by the current radio cal value show
2522 in the 'c s' command. For an unprogrammed board, the default value
2523 is 1186611. Take the resulting integer and program it using the 'c f'
2524 command. Testing with the 'C' command again should show a carrier
2525 within a few tens of Hertz of the intended frequency.
2526 As with all 'c' sub-commands, follow this with a 'c w' to write the
2527 change to the parameter block in the on-board DataFlash chip.
2530 Note that any time you re-do the radio frequency calibration, the
2531 radio frequency is reset to the default 434.550 Mhz. If you want
2532 to use another frequency, you will have to set that again after
2533 calibration is completed.
2537 <title>TeleMetrum Accelerometer</title>
2539 The TeleMetrum accelerometer we use has its own 5 volt power
2541 the output must be passed through a resistive voltage divider to match
2542 the input of our 3.3 volt ADC. This means that unlike the barometric
2543 sensor, the output of the acceleration sensor is not ratio-metric to
2544 the ADC converter, and calibration is required. Explicitly
2545 calibrating the accelerometers also allows us to load any device
2546 from a Freescale family that includes at least +/- 40g, 50g, 100g,
2547 and 200g parts. Using gravity,
2548 a simple 2-point calibration yields acceptable results capturing both
2549 the different sensitivities and ranges of the different accelerometer
2550 parts and any variation in power supply voltages or resistor values
2551 in the divider network.
2554 To calibrate the acceleration sensor, use the 'c a 0' command. You
2555 will be prompted to orient the board vertically with the UHF antenna
2556 up and press a key, then to orient the board vertically with the
2557 UHF antenna down and press a key. Note that the accuracy of this
2558 calibration depends primarily on how perfectly vertical and still
2559 the board is held during the cal process. As with all 'c'
2560 sub-commands, follow this with a 'c w' to write the
2561 change to the parameter block in the on-board DataFlash chip.
2564 The +1g and -1g calibration points are included in each telemetry
2565 frame and are part of the header stored in onboard flash to be
2566 downloaded after flight. We always store and return raw ADC
2567 samples for each sensor... so nothing is permanently "lost" or
2568 "damaged" if the calibration is poor.
2571 In the unlikely event an accel cal goes badly, it is possible
2572 that TeleMetrum may always come up in 'pad mode' and as such not be
2573 listening to either the USB or radio link. If that happens,
2574 there is a special hook in the firmware to force the board back
2575 in to 'idle mode' so you can re-do the cal. To use this hook, you
2576 just need to ground the SPI clock pin at power-on. This pin is
2577 available as pin 2 on the 8-pin companion connector, and pin 1 is
2578 ground. So either carefully install a fine-gauge wire jumper
2579 between the two pins closest to the index hole end of the 8-pin
2580 connector, or plug in the programming cable to the 8-pin connector
2581 and use a small screwdriver or similar to short the two pins closest
2582 to the index post on the 4-pin end of the programming cable, and
2583 power up the board. It should come up in 'idle mode' (two beeps),
2589 xmlns:xi="http://www.w3.org/2001/XInclude">
2590 <title>Release Notes</title>
2591 <xi:include href="release-notes-1.1.1.xsl" xpointer="xpointer(/article/*)"/>
2592 <xi:include href="release-notes-1.1.xsl" xpointer="xpointer(/article/*)"/>
2593 <xi:include href="release-notes-1.0.1.xsl" xpointer="xpointer(/article/*)"/>
2594 <xi:include href="release-notes-0.9.2.xsl" xpointer="xpointer(/article/*)"/>
2595 <xi:include href="release-notes-0.9.xsl" xpointer="xpointer(/article/*)"/>
2596 <xi:include href="release-notes-0.8.xsl" xpointer="xpointer(/article/*)"/>
2597 <xi:include href="release-notes-0.7.1.xsl" xpointer="xpointer(/article/*)"/>
2601 <!-- LocalWords: Altusmetrum
projects / fw / altos / blob