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5 <title>The Altus Metrum System</title>
6 <subtitle>An Owner's Manual for TeleMetrum, TeleMini, TeleDongle and TeleBT 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>1.3</revnumber>
40 <date>12 November 2013</date>
42 Updated for software version 1.3. Version 1.3 adds support
43 for TeleMega, TeleMetrum v2.0, TeleMini v2.0 and EasyMini
44 and fixes bugs in AltosUI and the AltOS firmware.
48 <revnumber>1.2.1</revnumber>
49 <date>21 May 2013</date>
51 Updated for software version 1.2. Version 1.2 adds support
52 for TeleBT and AltosDroid. It also adds a few minor features
53 and fixes bugs in AltosUI and the AltOS firmware.
57 <revnumber>1.2</revnumber>
58 <date>18 April 2013</date>
60 Updated for software version 1.2. Version 1.2 adds support
61 for MicroPeak and the MicroPeak USB interface.
65 <revnumber>1.1.1</revnumber>
66 <date>16 September 2012</date>
68 Updated for software version 1.1.1 Version 1.1.1 fixes a few
69 bugs found in version 1.1.
73 <revnumber>1.1</revnumber>
74 <date>13 September 2012</date>
76 Updated for software version 1.1. Version 1.1 has new
77 features but is otherwise compatible with version 1.0.
81 <revnumber>1.0</revnumber>
82 <date>24 August 2011</date>
84 Updated for software version 1.0. Note that 1.0 represents a
85 telemetry format change, meaning both ends of a link
86 (TeleMetrum/TeleMini and TeleDongle) must be updated or
87 communications will fail.
91 <revnumber>0.9</revnumber>
92 <date>18 January 2011</date>
94 Updated for software version 0.9. Note that 0.9 represents a
95 telemetry format change, meaning both ends of a link (TeleMetrum and
96 TeleDongle) must be updated or communications will fail.
100 <revnumber>0.8</revnumber>
101 <date>24 November 2010</date>
102 <revremark>Updated for software version 0.8 </revremark>
107 <title>Acknowledgements</title>
109 Thanks to Bob Finch, W9YA, NAR 12965, TRA 12350 for writing "The
110 Mere-Mortals Quick Start/Usage Guide to the Altus Metrum Starter
111 Kit" which formed the basis of the original Getting Started chapter
112 in this manual. Bob was one of our first customers for a production
113 TeleMetrum, and his continued enthusiasm and contributions
114 are immensely gratifying and highly appreciated!
117 And thanks to Anthony (AJ) Towns for major contributions including
118 the AltosUI graphing and site map code and associated documentation.
119 Free software means that our customers and friends can become our
120 collaborators, and we certainly appreciate this level of
124 Have fun using these products, and we hope to meet all of you
125 out on the rocket flight line somewhere.
128 NAR #87103, TRA #12201
130 Keith Packard, KD7SQG
131 NAR #88757, TRA #12200
136 <title>Introduction and Overview</title>
138 Welcome to the Altus Metrum community! Our circuits and software reflect
139 our passion for both hobby rocketry and Free Software. We hope their
140 capabilities and performance will delight you in every way, but by
141 releasing all of our hardware and software designs under open licenses,
142 we also hope to empower you to take as active a role in our collective
146 The first device created for our community was TeleMetrum, a dual
147 deploy altimeter with fully integrated GPS and radio telemetry
148 as standard features, and a "companion interface" that will
149 support optional capabilities in the future. The latest version
150 of TeleMetrum, v2.0, has all of the same features but with
151 improved sensors and radio to offer increased performance.
154 Our second device was TeleMini, a dual deploy altimeter with
155 radio telemetry and radio direction finding. The first version
156 of this device was only 13mm by 38mm (½ inch by 1½ inches) and
157 could fit easily in an 18mm air-frame. The latest version, v2.0,
158 includes a beeper, USB data download and extended on-board
159 flight logging, along with an improved barometric sensor.
162 TeleMega is our most sophisticated device, including six pyro
163 channels (four of which are fully programmable), integrated GPS,
164 integrated gyroscopes for staging/air-start inhibit and high
165 performance telemetry.
168 EasyMini is a dual-deploy altimeter with logging and built-in
172 TeleDongle was our first ground station, providing a USB to RF
173 interfaces for communicating with the altimeters. Combined with
174 your choice of antenna and notebook computer, TeleDongle and our
175 associated user interface software form a complete ground
176 station capable of logging and displaying in-flight telemetry,
177 aiding rocket recovery, then processing and archiving flight
178 data for analysis and review.
181 For a slightly more portable ground station experience that also
182 provides direct rocket recovery support, TeleBT offers flight
183 monitoring and data logging using a Bluetooth connection between
184 the receiver and an Android device that has the Altos Droid
185 application installed from the Google Play store.
188 More products will be added to the Altus Metrum family over time, and
189 we currently envision that this will be a single, comprehensive manual
190 for the entire product family.
194 <title>Getting Started</title>
196 The first thing to do after you check the inventory of parts in your
197 "starter kit" is to charge the battery.
200 For TeleMetrum and TeleMega, the battery can be charged by plugging it into the
201 corresponding socket of the device and then using the USB
202 cable to plug the flight computer into your computer's USB socket. The
203 on-board circuitry will charge the battery whenever it is plugged
204 in, because the on-off switch does NOT control the
208 On TeleMetrum v1 boards, when the GPS chip is initially
209 searching for satellites, TeleMetrum will consume more current
210 than it can pull from the USB port, so the battery must be
211 attached in order to get satellite lock. Once GPS is locked,
212 the current consumption goes back down enough to enable charging
213 while running. So it's a good idea to fully charge the battery
214 as your first item of business so there is no issue getting and
215 maintaining satellite lock. The yellow charge indicator led
216 will go out when the battery is nearly full and the charger goes
217 to trickle charge. It can take several hours to fully recharge a
218 deeply discharged battery.
221 TeleMetrum v2.0 and TeleMega use a higher power battery charger,
222 allowing them to charge the battery while running the board at
223 maximum power. When the battery is charging, or when the board
224 is consuming a lot of power, the red LED will be lit. When the
225 battery is fully charged, the green LED will be lit. When the
226 battery is damaged or missing, both LEDs will be lit, which
230 The Lithium Polymer TeleMini and EasyMini battery can be charged by
231 disconnecting it from the board and plugging it into a
232 standalone battery charger such as the LipoCharger product
233 included in TeleMini Starter Kits, and connecting that via a USB
234 cable to a laptop or other USB power source.
237 You can also choose to use another battery with TeleMini v2.0
238 and EasyMini, anything supplying between 4 and 12 volts should
239 work fine (like a standard 9V battery), but if you are planning
240 to fire pyro charges, ground testing is required to verify that
241 the battery supplies enough current.
244 The other active device in the starter kit is the TeleDongle USB to
245 RF interface. If you plug it in to your Mac or Linux computer it should
246 "just work", showing up as a serial port device. Windows systems need
247 driver information that is part of the AltOS download to know that the
248 existing USB modem driver will work. We therefore recommend installing
249 our software before plugging in TeleDongle if you are using a Windows
250 computer. If you are using Linux and are having problems, try moving
251 to a fresher kernel (2.6.33 or newer), as the USB serial driver had
252 ugly bugs in some earlier versions.
255 Next you should obtain and install the AltOS software. These
256 include the AltosUI ground station program, current firmware
257 images for all of the hardware, and a number of standalone
258 utilities that are rarely needed. Pre-built binary packages are
259 available for Linux, Microsoft Windows, and recent MacOSX
260 versions. Full source code and build instructions are also
261 available. The latest version may always be downloaded from
262 <ulink url="http://altusmetrum.org/AltOS"/>.
265 If you're using a TeleBT instead of the TeleDongle, you'll want
266 to go install the Altos Droid application from the Google Play
267 store. You don't need a data plan to use Altos Droid, but
268 without network access, the Map view will be less useful as it
269 won't contain any map data. You can also use TeleBT connected
270 over USB with your laptop computer; it acts exactly like a
271 TeleDongle. Anywhere this manual talks about TeleDongle, you can
272 also read that as 'and TeleBT when connected via USB'.
276 <title>Handling Precautions</title>
278 All Altus Metrum products are sophisticated electronic devices.
279 When handled gently and properly installed in an air-frame, they
280 will deliver impressive results. However, as with all electronic
281 devices, there are some precautions you must take.
284 The Lithium Polymer rechargeable batteries have an
285 extraordinary power density. This is great because we can fly with
286 much less battery mass than if we used alkaline batteries or previous
287 generation rechargeable batteries... but if they are punctured
288 or their leads are allowed to short, they can and will release their
290 Thus we recommend that you take some care when handling our batteries
291 and consider giving them some extra protection in your air-frame. We
292 often wrap them in suitable scraps of closed-cell packing foam before
293 strapping them down, for example.
296 The barometric sensors used on all of our flight computers are
297 sensitive to sunlight. In normal mounting situations, the baro sensor
298 and all of the other surface mount components
299 are "down" towards whatever the underlying mounting surface is, so
300 this is not normally a problem. Please consider this, though, when
301 designing an installation, for example, in an air-frame with a
302 see-through plastic payload bay. It is particularly important to
303 consider this with TeleMini v1.0, both because the baro sensor is on the
304 "top" of the board, and because many model rockets with payload bays
305 use clear plastic for the payload bay! Replacing these with an opaque
306 cardboard tube, painting them, or wrapping them with a layer of masking
307 tape are all reasonable approaches to keep the sensor out of direct
311 The barometric sensor sampling port must be able to "breathe",
312 both by not being covered by foam or tape or other materials that might
313 directly block the hole on the top of the sensor, and also by having a
314 suitable static vent to outside air.
317 As with all other rocketry electronics, Altus Metrum altimeters must
318 be protected from exposure to corrosive motor exhaust and ejection
323 <title>Altus Metrum Hardware</title>
325 <title>Overview</title>
327 Here's the full set of Altus Metrum products, both in
328 production and retired.
331 <title>Altus Metrum Electronics</title>
332 <tgroup cols='8' align='center' colsep='1' rowsep='1'>
333 <colspec align='center' colwidth='*' colname='Device'/>
334 <colspec align='center' colwidth='*' colname='Barometer'/>
335 <colspec align='center' colwidth='*' colname='Z-axis accelerometer'/>
336 <colspec align='center' colwidth='*' colname='GPS'/>
337 <colspec align='center' colwidth='*' colname='3D sensors'/>
338 <colspec align='center' colwidth='*' colname='Storage'/>
339 <colspec align='center' colwidth='*' colname='RF'/>
340 <colspec align='center' colwidth='*' colname='Battery'/>
343 <entry align='center'>Device</entry>
344 <entry align='center'>Barometer</entry>
345 <entry align='center'>Z-axis accelerometer</entry>
346 <entry align='center'>GPS</entry>
347 <entry align='center'>3D sensors</entry>
348 <entry align='center'>Storage</entry>
349 <entry align='center'>RF Output</entry>
350 <entry align='center'>Battery</entry>
355 <entry>TeleMetrum v1.0</entry>
356 <entry><para>MP3H6115 10km (33k')</para></entry>
357 <entry><para>MMA2202 50g</para></entry>
358 <entry>SkyTraq</entry>
365 <entry>TeleMetrum v1.1</entry>
366 <entry><para>MP3H6115 10km (33k')</para></entry>
367 <entry><para>MMA2202 50g</para></entry>
368 <entry>SkyTraq</entry>
375 <entry>TeleMetrum v1.2</entry>
376 <entry><para>MP3H6115 10km (33k')</para></entry>
377 <entry><para>ADXL78 70g</para></entry>
378 <entry>SkyTraq</entry>
385 <entry>TeleMetrum v2.0</entry>
386 <entry><para>MS5607 30km (100k')</para></entry>
387 <entry><para>MMA6555 102g</para></entry>
388 <entry>uBlox Max-7Q</entry>
395 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
396 <entry><para>MP3H6115 10km (33k')</para></entry>
405 <entry>TeleMini <?linebreak?>v2.0</entry>
406 <entry><para>MS5607 30km (100k')</para></entry>
412 <entry>3.7-12V</entry>
415 <entry>EasyMini <?linebreak?>v1.0</entry>
416 <entry><para>MS5607 30km (100k')</para></entry>
422 <entry>3.7-12V</entry>
425 <entry>TeleMega <?linebreak?>v1.0</entry>
426 <entry><para>MS5607 30km (100k')</para></entry>
427 <entry><para>MMA6555 102g</para></entry>
428 <entry>uBlox Max-7Q</entry>
429 <entry><para>MPU6000 HMC5883</para></entry>
438 <title>Altus Metrum Boards</title>
439 <tgroup cols='6' align='center' colsep='1' rowsep='1'>
440 <colspec align='center' colwidth='*' colname='Device'/>
441 <colspec align='center' colwidth='*' colname='Connectors'/>
442 <colspec align='center' colwidth='*' colname='Screw Terminals'/>
443 <colspec align='center' colwidth='*' colname='Width'/>
444 <colspec align='center' colwidth='*' colname='Length'/>
445 <colspec align='center' colwidth='*' colname='Tube Size'/>
448 <entry align='center'>Device</entry>
449 <entry align='center'>Connectors</entry>
450 <entry align='center'>Screw Terminals</entry>
451 <entry align='center'>Width</entry>
452 <entry align='center'>Length</entry>
453 <entry align='center'>Tube Size</entry>
458 <entry>TeleMetrum</entry>
462 Companion<?linebreak?>
466 <entry><para>Apogee pyro <?linebreak?>Main pyro <?linebreak?>Switch</para></entry>
467 <entry>1 inch (2.54cm)</entry>
468 <entry>2 ¾ inch (6.99cm)</entry>
469 <entry>29mm coupler</entry>
472 <entry><para>TeleMini <?linebreak?>v1.0</para></entry>
479 Apogee pyro <?linebreak?>
482 <entry>½ inch (1.27cm)</entry>
483 <entry>1½ inch (3.81cm)</entry>
484 <entry>18mm aiframe</entry>
487 <entry>TeleMini <?linebreak?>v2.0</entry>
495 Apogee pyro <?linebreak?>
496 Main pyro <?linebreak?>
497 Battery <?linebreak?>
500 <entry>0.8 inch (2.03cm)</entry>
501 <entry>1½ inch (3.81cm)</entry>
502 <entry>24mm coupler</entry>
505 <entry>EasyMini</entry>
512 Apogee pyro <?linebreak?>
513 Main pyro <?linebreak?>
514 Battery <?linebreak?>
517 <entry>0.8 inch (2.03cm)</entry>
518 <entry>1½ inch (3.81cm)</entry>
519 <entry>24mm coupler</entry>
522 <entry>TeleMega</entry>
526 Companion<?linebreak?>
531 Apogee pyro <?linebreak?>
532 Main pyro<?linebreak?>
533 Pyro A-D<?linebreak?>
537 <entry>1¼ inch (3.18cm)</entry>
538 <entry>3¼ inch (8.26cm)</entry>
539 <entry>38mm coupler</entry>
546 <title>TeleMetrum</title>
548 TeleMetrum is a 1 inch by 2¾ inch circuit board. It was designed to
549 fit inside coupler for 29mm air-frame tubing, but using it in a tube that
550 small in diameter may require some creativity in mounting and wiring
551 to succeed! The presence of an accelerometer means TeleMetrum should
552 be aligned along the flight axis of the airframe, and by default the 1/4
553 wave UHF wire antenna should be on the nose-cone end of the board. The
554 antenna wire is about 7 inches long, and wiring for a power switch and
555 the e-matches for apogee and main ejection charges depart from the
556 fin can end of the board, meaning an ideal "simple" avionics
557 bay for TeleMetrum should have at least 10 inches of interior length.
561 <title>TeleMini</title>
563 TeleMini v1.0 is ½ inches by 1½ inches. It was
564 designed to fit inside an 18mm air-frame tube, but using it in
565 a tube that small in diameter may require some creativity in
566 mounting and wiring to succeed! Since there is no
567 accelerometer, TeleMini can be mounted in any convenient
568 orientation. The default ¼ wave UHF wire antenna attached to
569 the center of one end of the board is about 7 inches long. Two
570 wires for the power switch are connected to holes in the
571 middle of the board. Screw terminals for the e-matches for
572 apogee and main ejection charges depart from the other end of
573 the board, meaning an ideal "simple" avionics bay for TeleMini
574 should have at least 9 inches of interior length.
577 TeleMini v2.0 is 0.8 inches by 1½ inches. It adds more
578 on-board data logging memory, a built-in USB connector and
579 screw terminals for the battery and power switch. The larger
580 board fits in a 24mm coupler. There's also a battery connector
581 for a LiPo battery if you want to use one of those.
585 <title>EasyMini</title>
587 EasyMini is built on a 0.8 inch by 1½ inch circuit board. It's
588 designed to fit in a 24mm coupler tube. The connectors and
589 screw terminals match TeleMini, so you can swap an EasyMini
594 <title>TeleMega</title>
596 TeleMega is a 1¼ inch by 3¼ inch circuit board. It was
597 designed to easily fit in a 38mm coupler. Like TeleMetrum,
598 TeleMega has an accelerometer and so it must be mounted so that
599 the board is aligned with the flight axis. It can be mounted
600 either antenna up or down.
604 <title>Flight Data Recording</title>
606 Each flight computer logs data at 100 samples per second
607 during ascent and 10 samples per second during descent, except
608 for TeleMini v1.0, which records ascent at 10 samples per
609 second and descent at 1 sample per second. Data are logged to
610 an on-board flash memory part, which can be partitioned into
611 several equal-sized blocks, one for each flight.
614 <title>Data Storage on Altus Metrum altimeters</title>
615 <tgroup cols='4' align='center' colsep='1' rowsep='1'>
616 <colspec align='center' colwidth='*' colname='Device'/>
617 <colspec align='center' colwidth='*' colname='Bytes per sample'/>
618 <colspec align='center' colwidth='*' colname='Total storage'/>
619 <colspec align='center' colwidth='*' colname='Minutes of
623 <entry align='center'>Device</entry>
624 <entry align='center'>Bytes per Sample</entry>
625 <entry align='center'>Total Storage</entry>
626 <entry align='center'>Minutes at Full Rate</entry>
631 <entry>TeleMetrum v1.0</entry>
637 <entry>TeleMetrum v1.1 v1.2</entry>
643 <entry>TeleMetrum v2.0</entry>
649 <entry>TeleMini v1.0</entry>
655 <entry>TeleMini v2.0</entry>
661 <entry>EasyMini</entry>
667 <entry>TeleMega</entry>
676 The on-board flash is partitioned into separate flight logs,
677 each of a fixed maximum size. Increase the maximum size of
678 each log and you reduce the number of flights that can be
679 stored. Decrease the size and you can store more flights.
682 Configuration data is also stored in the flash memory on
683 TeleMetrum v1.x, TeleMini and EasyMini. This consumes 64kB
684 of flash space. This configuration space is not available
685 for storing flight log data. TeleMetrum v2.0 and TeleMega
686 store configuration data in a bit of eeprom available within
687 the processor chip, leaving that space available in flash for
691 To compute the amount of space needed for a single flight, you
692 can multiply the expected ascent time (in seconds) by 100
693 times bytes-per-sample, multiply the expected descent time (in
694 seconds) by 10 times the bytes per sample and add the two
695 together. That will slightly under-estimate the storage (in
696 bytes) needed for the flight. For instance, a TeleMetrum v2.0 flight spending
697 20 seconds in ascent and 150 seconds in descent will take
698 about (20 * 1600) + (150 * 160) = 56000 bytes of storage. You
699 could store dozens of these flights in the on-board flash.
702 The default size allows for several flights on each flight
703 computer, except for TeleMini v1.0, which only holds data for a
704 single flight. You can adjust the size.
707 Altus Metrum flight computers will not overwrite existing
708 flight data, so be sure to download flight data and erase it
709 from the flight computer before it fills up. The flight
710 computer will still successfully control the flight even if it
711 cannot log data, so the only thing you will lose is the data.
715 <title>Installation</title>
717 A typical installation involves attaching
718 only a suitable battery, a single pole switch for
719 power on/off, and two pairs of wires connecting e-matches for the
720 apogee and main ejection charges. All Altus Metrum products are
721 designed for use with single-cell batteries with 3.7 volts
722 nominal. TeleMini v2.0 and EasyMini may also be used with other
723 batteries as long as they supply between 4 and 12 volts.
726 The battery connectors are a standard 2-pin JST connector and
727 match batteries sold by Spark Fun. These batteries are
728 single-cell Lithium Polymer batteries that nominally provide 3.7
729 volts. Other vendors sell similar batteries for RC aircraft
730 using mating connectors, however the polarity for those is
731 generally reversed from the batteries used by Altus Metrum
732 products. In particular, the Tenergy batteries supplied for use
733 in Featherweight flight computers are not compatible with Altus
734 Metrum flight computers or battery chargers. <emphasis>Check
735 polarity and voltage before connecting any battery not purchased
736 from Altus Metrum or Spark Fun.</emphasis>
739 By default, we use the unregulated output of the battery directly
740 to fire ejection charges. This works marvelously with standard
741 low-current e-matches like the J-Tek from MJG Technologies, and with
742 Quest Q2G2 igniters. However, if you want or need to use a separate
743 pyro battery, check out the "External Pyro Battery" section in this
744 manual for instructions on how to wire that up. The altimeters are
745 designed to work with an external pyro battery of no more than 15 volts.
749 Ejection charges are wired directly to the screw terminal block
750 at the aft end of the altimeter. You'll need a very small straight
751 blade screwdriver for these screws, such as you might find in a
752 jeweler's screwdriver set.
755 Except for TeleMini v1.0, the flight computers also use the
756 screw terminal block for the power switch leads. On TeleMini v1.0,
757 the power switch leads are soldered directly to the board and
758 can be connected directly to a switch.
761 For most air-frames, the integrated antennas are more than
762 adequate. However, if you are installing in a carbon-fiber or
763 metal electronics bay which is opaque to RF signals, you may need to
764 use off-board external antennas instead. In this case, you can
765 order an altimeter with an SMA connector for the UHF antenna
766 connection, and, on TeleMetrum v1, you can unplug the integrated GPS
767 antenna and select an appropriate off-board GPS antenna with
768 cable terminating in a U.FL connector.
773 <title>System Operation</title>
775 <title>Firmware Modes </title>
777 The AltOS firmware build for the altimeters has two
778 fundamental modes, "idle" and "flight". Which of these modes
779 the firmware operates in is determined at start up time. For
780 TeleMetrum, the mode is controlled by the orientation of the
781 rocket (well, actually the board, of course...) at the time
782 power is switched on. If the rocket is "nose up", then
783 TeleMetrum assumes it's on a rail or rod being prepared for
784 launch, so the firmware chooses flight mode. However, if the
785 rocket is more or less horizontal, the firmware instead enters
786 idle mode. Since TeleMini v2.0 and EasyMini don't have an
787 accelerometer we can use to determine orientation, "idle" mode
788 is selected if the board is connected via USB to a computer,
789 otherwise the board enters "flight" mode. TeleMini v1.0
790 selects "idle" mode if it receives a command packet within the
791 first five seconds of operation.
794 At power on, you will hear three beeps or see three flashes
795 ("S" in Morse code for start up) and then a pause while
796 the altimeter completes initialization and self test, and decides
797 which mode to enter next.
800 In flight or "pad" mode, the altimeter engages the flight
801 state machine, goes into transmit-only mode to
802 send telemetry, and waits for launch to be detected.
803 Flight mode is indicated by an "di-dah-dah-dit" ("P" for pad)
804 on the beeper or lights, followed by beeps or flashes
805 indicating the state of the pyrotechnic igniter continuity.
806 One beep/flash indicates apogee continuity, two beeps/flashes
807 indicate main continuity, three beeps/flashes indicate both
808 apogee and main continuity, and one longer "brap" sound or
809 rapidly alternating lights indicates no continuity. For a
810 dual deploy flight, make sure you're getting three beeps or
811 flashes before launching! For apogee-only or motor eject
812 flights, do what makes sense.
815 If idle mode is entered, you will hear an audible "di-dit" or
816 see two short flashes ("I" for idle), and the flight state
817 machine is disengaged, thus no ejection charges will fire.
818 The altimeters also listen for the radio link when in idle
819 mode for requests sent via TeleDongle. Commands can be issued
820 in idle mode over either USB or the radio link
821 equivalently. TeleMini v1.0 only has the radio link. Idle
822 mode is useful for configuring the altimeter, for extracting
823 data from the on-board storage chip after flight, and for
824 ground testing pyro charges.
827 One "neat trick" of particular value when TeleMetrum or TeleMega are used with
828 very large air-frames, is that you can power the board up while the
829 rocket is horizontal, such that it comes up in idle mode. Then you can
830 raise the air-frame to launch position, and issue a 'reset' command
831 via TeleDongle over the radio link to cause the altimeter to reboot and
832 come up in flight mode. This is much safer than standing on the top
833 step of a rickety step-ladder or hanging off the side of a launch
834 tower with a screw-driver trying to turn on your avionics before
838 TeleMini v1.0 is configured solely via the radio link. Of course, that
839 means you need to know the TeleMini radio configuration values
840 or you won't be able to communicate with it. For situations
841 when you don't have the radio configuration values, TeleMini v1.0
842 offers an 'emergency recovery' mode. In this mode, TeleMini is
843 configured as follows:
847 Sets the radio frequency to 434.550MHz
852 Sets the radio calibration back to the factory value.
857 Sets the callsign to N0CALL
862 Does not go to 'pad' mode after five seconds.
868 To get into 'emergency recovery' mode, first find the row of
869 four small holes opposite the switch wiring. Using a short
870 piece of small gauge wire, connect the outer two holes
871 together, then power TeleMini up. Once the red LED is lit,
872 disconnect the wire and the board should signal that it's in
873 'idle' mode after the initial five second startup period.
879 TeleMetrum and TeleMega include a complete GPS receiver. A
880 complete explanation of how GPS works is beyond the scope of
881 this manual, but the bottom line is that the GPS receiver
882 needs to lock onto at least four satellites to obtain a solid
883 3 dimensional position fix and know what time it is.
886 The flight computers provide backup power to the GPS chip any time a
887 battery is connected. This allows the receiver to "warm start" on
888 the launch rail much faster than if every power-on were a GPS
889 "cold start". In typical operations, powering up
890 on the flight line in idle mode while performing final air-frame
891 preparation will be sufficient to allow the GPS receiver to cold
892 start and acquire lock. Then the board can be powered down during
893 RSO review and installation on a launch rod or rail. When the board
894 is turned back on, the GPS system should lock very quickly, typically
895 long before igniter installation and return to the flight line are
900 <title>Controlling An Altimeter Over The Radio Link</title>
902 One of the unique features of the Altus Metrum system is the
903 ability to create a two way command link between TeleDongle
904 and an altimeter using the digital radio transceivers
905 built into each device. This allows you to interact with the
906 altimeter from afar, as if it were directly connected to the
910 Any operation which can be performed with a flight computer can
911 either be done with the device directly connected to the
912 computer via the USB cable, or through the radio
913 link. TeleMini v1.0 doesn't provide a USB connector and so it is
914 always communicated with over radio. Select the appropriate
915 TeleDongle device when the list of devices is presented and
916 AltosUI will interact with an altimeter over the radio link.
919 One oddity in the current interface is how AltosUI selects the
920 frequency for radio communications. Instead of providing
921 an interface to specifically configure the frequency, it uses
922 whatever frequency was most recently selected for the target
923 TeleDongle device in Monitor Flight mode. If you haven't ever
924 used that mode with the TeleDongle in question, select the
925 Monitor Flight button from the top level UI, and pick the
926 appropriate TeleDongle device. Once the flight monitoring
927 window is open, select the desired frequency and then close it
928 down again. All radio communications will now use that frequency.
933 Save Flight Data—Recover flight data from the rocket without
939 Configure altimeter apogee delays, main deploy heights
940 and additional pyro event conditions
941 to respond to changing launch conditions. You can also
942 'reboot' the altimeter. Use this to remotely enable the
943 flight computer by turning TeleMetrum or TeleMega on in "idle" mode,
944 then once the air-frame is oriented for launch, you can
945 reboot the altimeter and have it restart in pad mode
946 without having to climb the scary ladder.
951 Fire Igniters—Test your deployment charges without snaking
952 wires out through holes in the air-frame. Simply assemble the
953 rocket as if for flight with the apogee and main charges
954 loaded, then remotely command the altimeter to fire the
960 Operation over the radio link for configuring an altimeter, ground
961 testing igniters, and so forth uses the same RF frequencies as flight
962 telemetry. To configure the desired TeleDongle frequency, select
963 the monitor flight tab, then use the frequency selector and
964 close the window before performing other desired radio operations.
967 The flight computers only enable radio commanding in 'idle' mode.
968 TeleMetrum and TeleMega use the accelerometer to detect which orientation they
969 start up in, so make sure you have the flight computer lying horizontally when you turn
970 it on. Otherwise, it will start in 'pad' mode ready for
971 flight, and will not be listening for command packets from TeleDongle.
974 TeleMini listens for a command packet for five seconds after
975 first being turned on, if it doesn't hear anything, it enters
976 'pad' mode, ready for flight and will no longer listen for
977 command packets. The easiest way to connect to TeleMini is to
978 initiate the command and select the TeleDongle device. At this
979 point, the TeleDongle will be attempting to communicate with
980 the TeleMini. Now turn TeleMini on, and it should immediately
981 start communicating with the TeleDongle and the desired
982 operation can be performed.
985 You can monitor the operation of the radio link by watching the
986 lights on the devices. The red LED will flash each time a packet
987 is transmitted, while the green LED will light up on TeleDongle when
988 it is waiting to receive a packet from the altimeter.
992 <title>Ground Testing </title>
994 An important aspect of preparing a rocket using electronic deployment
995 for flight is ground testing the recovery system. Thanks
996 to the bi-directional radio link central to the Altus Metrum system,
997 this can be accomplished in a TeleMega, TeleMetrum or TeleMini equipped rocket
998 with less work than you may be accustomed to with other systems. It
1002 Just prep the rocket for flight, then power up the altimeter
1003 in "idle" mode (placing air-frame horizontal for TeleMetrum or TeleMega, or
1004 selecting the Configure Altimeter tab for TeleMini). This will cause
1005 the firmware to go into "idle" mode, in which the normal flight
1006 state machine is disabled and charges will not fire without
1007 manual command. You can now command the altimeter to fire the apogee
1008 or main charges from a safe distance using your computer and
1009 TeleDongle and the Fire Igniter tab to complete ejection testing.
1013 <title>Radio Link </title>
1015 The chip our boards are based on incorporates an RF transceiver, but
1016 it's not a full duplex system... each end can only be transmitting or
1017 receiving at any given moment. So we had to decide how to manage the
1021 By design, the altimeter firmware listens for the radio link when
1022 it's in "idle mode", which
1023 allows us to use the radio link to configure the rocket, do things like
1024 ejection tests, and extract data after a flight without having to
1025 crack open the air-frame. However, when the board is in "flight
1026 mode", the altimeter only
1027 transmits and doesn't listen at all. That's because we want to put
1028 ultimate priority on event detection and getting telemetry out of
1030 the radio in case the rocket crashes and we aren't able to extract
1034 We don't generally use a 'normal packet radio' mode like APRS
1035 because they're just too inefficient. The GFSK modulation we
1036 use is FSK with the base-band pulses passed through a Gaussian
1037 filter before they go into the modulator to limit the
1038 transmitted bandwidth. When combined with forward error
1039 correction and interleaving, this allows us to have a very
1040 robust 19.2 kilobit data link with only 10-40 milliwatts of
1041 transmit power, a whip antenna in the rocket, and a hand-held
1042 Yagi on the ground. We've had flights to above 21k feet AGL
1043 with great reception, and calculations suggest we should be
1044 good to well over 40k feet AGL with a 5-element yagi on the
1045 ground with our 10mW units and over 100k feet AGL with the
1046 40mW devices. We hope to fly boards to higher altitudes over
1047 time, and would of course appreciate customer feedback on
1048 performance in higher altitude flights!
1051 TeleMetrum v2.0 and TeleMega can send APRS if desired, the
1052 interval between APRS packets can be configured. As each APRS
1053 packet takes a full second to transmit, we recommend an
1054 interval of at least 5 seconds to avoid consuming too much
1055 battery power or radio channel bandwidth.
1059 <title>Configurable Parameters</title>
1061 Configuring an Altus Metrum altimeter for flight is very
1062 simple. Even on our baro-only TeleMini and EasyMini boards, the use of a Kalman
1063 filter means there is no need to set a "mach delay". The few
1064 configurable parameters can all be set using AltosUI over USB or
1065 or radio link via TeleDongle.
1068 <title>Radio Frequency</title>
1070 Altus Metrum boards support radio frequencies in the 70cm
1071 band. By default, the configuration interface provides a
1072 list of 10 "standard" frequencies in 100kHz channels starting at
1073 434.550MHz. However, the firmware supports use of
1074 any 50kHz multiple within the 70cm band. At any given
1075 launch, we highly recommend coordinating when and by whom each
1076 frequency will be used to avoid interference. And of course, both
1077 altimeter and TeleDongle must be configured to the same
1078 frequency to successfully communicate with each other.
1082 <title>Apogee Delay</title>
1084 Apogee delay is the number of seconds after the altimeter detects flight
1085 apogee that the drogue charge should be fired. In most cases, this
1086 should be left at the default of 0. However, if you are flying
1087 redundant electronics such as for an L3 certification, you may wish
1088 to set one of your altimeters to a positive delay so that both
1089 primary and backup pyrotechnic charges do not fire simultaneously.
1092 The Altus Metrum apogee detection algorithm fires exactly at
1093 apogee. If you are also flying an altimeter like the
1094 PerfectFlite MAWD, which only supports selecting 0 or 1
1095 seconds of apogee delay, you may wish to set the MAWD to 0
1096 seconds delay and set the TeleMetrum to fire your backup 2
1097 or 3 seconds later to avoid any chance of both charges
1098 firing simultaneously. We've flown several air-frames this
1099 way quite happily, including Keith's successful L3 cert.
1103 <title>Main Deployment Altitude</title>
1105 By default, the altimeter will fire the main deployment charge at an
1106 elevation of 250 meters (about 820 feet) above ground. We think this
1107 is a good elevation for most air-frames, but feel free to change this
1108 to suit. In particular, if you are flying two altimeters, you may
1110 deployment elevation for the backup altimeter to be something lower
1111 than the primary so that both pyrotechnic charges don't fire
1116 <title>Maximum Flight Log</title>
1118 Each flight computer logs data at 100 samples per second
1119 during ascent and 10 samples per second during descent. Data
1120 are logged to an on-board flash memory part, which can be
1121 partitioned into several equal-sized blocks, one for each
1125 <title>Data Storage on Altus Metrum altimeters</title>
1126 <tgroup cols='4' align='center' colsep='1' rowsep='1'>
1127 <colspec align='center' colwidth='*' colname='Device'/>
1128 <colspec align='center' colwidth='*' colname='Bytes per sample'/>
1129 <colspec align='center' colwidth='*' colname='Total storage'/>
1130 <colspec align='center' colwidth='*' colname='Minutes of
1134 <entry align='center'>Device</entry>
1135 <entry align='center'>Bytes per Sample</entry>
1136 <entry align='center'>Total Storage</entry>
1137 <entry align='center'>Minutes at Full Rate</entry>
1142 <entry>TeleMetrum v1.x</entry>
1151 The on-board flash is partitioned into separate flight logs,
1152 each of a fixed maximum size. Increase the maximum size of
1153 each log and you reduce the number of flights that can be
1154 stored. Decrease the size and TeleMetrum can store more
1158 Configuration data is also stored in the flash memory on
1159 TeleMetrum v1.x, TeleMini and EasyMini. This consumes 64kB
1160 of flash space. This configuration space is not available
1161 for storing flight log data. TeleMetrum v2.0 and TeleMega
1162 store configuration data in a bit of eeprom available within
1166 To compute the amount of space needed for a single flight,
1167 you can multiply the expected ascent time (in seconds) by
1168 100 times bytes-per-sample (8 for TeleMetrum v1.x, 16 for
1169 TeleMetrum v2.0 and 32 for TeleMega), multiply the expected
1170 descent time (in seconds) by 80 and add the two
1171 together. That will slightly under-estimate the storage (in
1172 bytes) needed for the flight. For instance, a flight
1173 spending 20 seconds in ascent and 150 seconds in descent
1174 will take about (20 * 800) + (150 * 80) = 28000 bytes of
1175 storage. You could store dozens of these flights in the
1179 The default size, 192kB, allows for 10 flights of storage on
1180 TeleMetrum v1.1/v1.2 and 5 flights on TeleMetrum v1.0. This
1181 ensures that you won't need to erase the memory before
1182 flying each time while still allowing more than sufficient
1183 storage for each flight.
1186 As TeleMini does not contain an accelerometer, it stores
1187 data at 10 samples per second during ascent and one sample
1188 per second during descent. Each sample is a two byte reading
1189 from the barometer. These are stored in 5kB of
1190 on-chip flash memory which can hold 256 seconds at the
1191 ascent rate or 2560 seconds at the descent rate. Because of
1192 the limited storage, TeleMini cannot hold data for more than
1193 one flight, and so must be erased after each flight or it
1194 will not capture data for subsequent flights.
1198 <title>Ignite Mode</title>
1200 Instead of firing one charge at apogee and another charge at
1201 a fixed height above the ground, you can configure the
1202 altimeter to fire both at apogee or both during
1203 descent. This was added to support an airframe that has two
1204 altimeters, one in the fin can and one in the
1208 Providing the ability to use both igniters for apogee or
1209 main allows some level of redundancy without needing two
1210 flight computers. In Redundant Apogee or Redundant Main
1211 mode, the two charges will be fired two seconds apart.
1215 <title>Pad Orientation</title>
1217 TeleMetrum and TeleMega measure acceleration along the axis
1218 of the board. Which way the board is oriented affects the
1219 sign of the acceleration value. Instead of trying to guess
1220 which way the board is mounted in the air frame, the
1221 altimeter must be explicitly configured for either Antenna
1222 Up or Antenna Down. The default, Antenna Up, expects the end
1223 of the board connected to the 70cm antenna to be nearest the
1224 nose of the rocket, with the end containing the screw
1225 terminals nearest the tail.
1229 <title>Pyro Channels</title>
1239 <title>AltosUI</title>
1241 The AltosUI program provides a graphical user interface for
1242 interacting with the Altus Metrum product family, including
1243 TeleMetrum, TeleMini and TeleDongle. AltosUI can monitor telemetry data,
1244 configure TeleMetrum, TeleMini and TeleDongle devices and many other
1245 tasks. The primary interface window provides a selection of
1246 buttons, one for each major activity in the system. This manual
1247 is split into chapters, each of which documents one of the tasks
1248 provided from the top-level toolbar.
1251 <title>Monitor Flight</title>
1252 <subtitle>Receive, Record and Display Telemetry Data</subtitle>
1254 Selecting this item brings up a dialog box listing all of the
1255 connected TeleDongle devices. When you choose one of these,
1256 AltosUI will create a window to display telemetry data as
1257 received by the selected TeleDongle device.
1260 All telemetry data received are automatically recorded in
1261 suitable log files. The name of the files includes the current
1262 date and rocket serial and flight numbers.
1265 The radio frequency being monitored by the TeleDongle device is
1266 displayed at the top of the window. You can configure the
1267 frequency by clicking on the frequency box and selecting the desired
1268 frequency. AltosUI remembers the last frequency selected for each
1269 TeleDongle and selects that automatically the next time you use
1273 Below the TeleDongle frequency selector, the window contains a few
1274 significant pieces of information about the altimeter providing
1275 the telemetry data stream:
1279 <para>The configured call-sign</para>
1282 <para>The device serial number</para>
1285 <para>The flight number. Each altimeter remembers how many
1291 The rocket flight state. Each flight passes through several
1292 states including Pad, Boost, Fast, Coast, Drogue, Main and
1298 The Received Signal Strength Indicator value. This lets
1299 you know how strong a signal TeleDongle is receiving. The
1300 radio inside TeleDongle operates down to about -99dBm;
1301 weaker signals may not be receivable. The packet link uses
1302 error detection and correction techniques which prevent
1303 incorrect data from being reported.
1308 The age of the displayed data, in seconds since the last
1309 successfully received telemetry packet. In normal operation
1310 this will stay in the low single digits. If the number starts
1311 counting up, then you are no longer receiving data over the radio
1312 link from the flight computer.
1317 Finally, the largest portion of the window contains a set of
1318 tabs, each of which contain some information about the rocket.
1319 They're arranged in 'flight order' so that as the flight
1320 progresses, the selected tab automatically switches to display
1321 data relevant to the current state of the flight. You can select
1322 other tabs at any time. The final 'table' tab displays all of
1323 the raw telemetry values in one place in a spreadsheet-like format.
1326 <title>Launch Pad</title>
1328 The 'Launch Pad' tab shows information used to decide when the
1329 rocket is ready for flight. The first elements include red/green
1330 indicators, if any of these is red, you'll want to evaluate
1331 whether the rocket is ready to launch:
1335 Battery Voltage. This indicates whether the Li-Po battery
1336 powering the TeleMetrum has sufficient charge to last for
1337 the duration of the flight. A value of more than
1338 3.7V is required for a 'GO' status.
1343 Apogee Igniter Voltage. This indicates whether the apogee
1344 igniter has continuity. If the igniter has a low
1345 resistance, then the voltage measured here will be close
1346 to the Li-Po battery voltage. A value greater than 3.2V is
1347 required for a 'GO' status.
1352 Main Igniter Voltage. This indicates whether the main
1353 igniter has continuity. If the igniter has a low
1354 resistance, then the voltage measured here will be close
1355 to the Li-Po battery voltage. A value greater than 3.2V is
1356 required for a 'GO' status.
1361 On-board Data Logging. This indicates whether there is
1362 space remaining on-board to store flight data for the
1363 upcoming flight. If you've downloaded data, but failed
1364 to erase flights, there may not be any space
1365 left. TeleMetrum can store multiple flights, depending
1366 on the configured maximum flight log size. TeleMini
1367 stores only a single flight, so it will need to be
1368 downloaded and erased after each flight to capture
1369 data. This only affects on-board flight logging; the
1370 altimeter will still transmit telemetry and fire
1371 ejection charges at the proper times.
1376 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
1377 currently able to compute position information. GPS requires
1378 at least 4 satellites to compute an accurate position.
1383 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
1384 10 consecutive positions without losing lock. This ensures
1385 that the GPS receiver has reliable reception from the
1392 The Launchpad tab also shows the computed launch pad position
1393 and altitude, averaging many reported positions to improve the
1394 accuracy of the fix.
1398 <title>Ascent</title>
1400 This tab is shown during Boost, Fast and Coast
1401 phases. The information displayed here helps monitor the
1402 rocket as it heads towards apogee.
1405 The height, speed and acceleration are shown along with the
1406 maximum values for each of them. This allows you to quickly
1407 answer the most commonly asked questions you'll hear during
1411 The current latitude and longitude reported by the TeleMetrum GPS are
1412 also shown. Note that under high acceleration, these values
1413 may not get updated as the GPS receiver loses position
1414 fix. Once the rocket starts coasting, the receiver should
1415 start reporting position again.
1418 Finally, the current igniter voltages are reported as in the
1419 Launch Pad tab. This can help diagnose deployment failures
1420 caused by wiring which comes loose under high acceleration.
1424 <title>Descent</title>
1426 Once the rocket has reached apogee and (we hope) activated the
1427 apogee charge, attention switches to tracking the rocket on
1428 the way back to the ground, and for dual-deploy flights,
1429 waiting for the main charge to fire.
1432 To monitor whether the apogee charge operated correctly, the
1433 current descent rate is reported along with the current
1434 height. Good descent rates vary based on the choice of recovery
1435 components, but generally range from 15-30m/s on drogue and should
1436 be below 10m/s when under the main parachute in a dual-deploy flight.
1439 For TeleMetrum altimeters, you can locate the rocket in the
1440 sky using the elevation and bearing information to figure
1441 out where to look. Elevation is in degrees above the
1442 horizon. Bearing is reported in degrees relative to true
1443 north. Range can help figure out how big the rocket will
1444 appear. Ground Distance shows how far it is to a point
1445 directly under the rocket and can help figure out where the
1446 rocket is likely to land. Note that all of these values are
1447 relative to the pad location. If the elevation is near 90°,
1448 the rocket is over the pad, not over you.
1451 Finally, the igniter voltages are reported in this tab as
1452 well, both to monitor the main charge as well as to see what
1453 the status of the apogee charge is. Note that some commercial
1454 e-matches are designed to retain continuity even after being
1455 fired, and will continue to show as green or return from red to
1460 <title>Landed</title>
1462 Once the rocket is on the ground, attention switches to
1463 recovery. While the radio signal is often lost once the
1464 rocket is on the ground, the last reported GPS position is
1465 generally within a short distance of the actual landing location.
1468 The last reported GPS position is reported both by
1469 latitude and longitude as well as a bearing and distance from
1470 the launch pad. The distance should give you a good idea of
1471 whether to walk or hitch a ride. Take the reported
1472 latitude and longitude and enter them into your hand-held GPS
1473 unit and have that compute a track to the landing location.
1476 Both TeleMini and TeleMetrum will continue to transmit RDF
1477 tones after landing, allowing you to locate the rocket by
1478 following the radio signal if necessary. You may need to get
1479 away from the clutter of the flight line, or even get up on
1480 a hill (or your neighbor's RV roof) to receive the RDF signal.
1483 The maximum height, speed and acceleration reported
1484 during the flight are displayed for your admiring observers.
1485 The accuracy of these immediate values depends on the quality
1486 of your radio link and how many packets were received.
1487 Recovering the on-board data after flight will likely yield
1488 more precise results.
1491 To get more detailed information about the flight, you can
1492 click on the 'Graph Flight' button which will bring up a
1493 graph window for the current flight.
1497 <title>Site Map</title>
1499 When the TeleMetrum has a GPS fix, the Site Map tab will map
1500 the rocket's position to make it easier for you to locate the
1501 rocket, both while it is in the air, and when it has landed. The
1502 rocket's state is indicated by color: white for pad, red for
1503 boost, pink for fast, yellow for coast, light blue for drogue,
1504 dark blue for main, and black for landed.
1507 The map's scale is approximately 3m (10ft) per pixel. The map
1508 can be dragged using the left mouse button. The map will attempt
1509 to keep the rocket roughly centered while data is being received.
1512 Images are fetched automatically via the Google Maps Static API,
1513 and cached on disk for reuse. If map images cannot be downloaded,
1514 the rocket's path will be traced on a dark gray background
1518 You can pre-load images for your favorite launch sites
1519 before you leave home; check out the 'Preload Maps' section below.
1524 <title>Save Flight Data</title>
1526 The altimeter records flight data to its internal flash memory.
1527 TeleMetrum data is recorded at a much higher rate than the telemetry
1528 system can handle, and is not subject to radio drop-outs. As
1529 such, it provides a more complete and precise record of the
1530 flight. The 'Save Flight Data' button allows you to read the
1531 flash memory and write it to disk. As TeleMini has only a barometer, it
1532 records data at the same rate as the telemetry signal, but there will be
1533 no data lost due to telemetry drop-outs.
1536 Clicking on the 'Save Flight Data' button brings up a list of
1537 connected TeleMetrum and TeleDongle devices. If you select a
1538 TeleMetrum device, the flight data will be downloaded from that
1539 device directly. If you select a TeleDongle device, flight data
1540 will be downloaded from an altimeter over radio link via the
1541 specified TeleDongle. See the chapter on Controlling An Altimeter
1542 Over The Radio Link for more information.
1545 After the device has been selected, a dialog showing the
1546 flight data saved in the device will be shown allowing you to
1547 select which flights to download and which to delete. With
1548 version 0.9 or newer firmware, you must erase flights in order
1549 for the space they consume to be reused by another
1550 flight. This prevents accidentally losing flight data
1551 if you neglect to download data before flying again. Note that
1552 if there is no more space available in the device, then no
1553 data will be recorded during the next flight.
1556 The file name for each flight log is computed automatically
1557 from the recorded flight date, altimeter serial number and
1558 flight number information.
1562 <title>Replay Flight</title>
1564 Select this button and you are prompted to select a flight
1565 record file, either a .telem file recording telemetry data or a
1566 .eeprom file containing flight data saved from the altimeter
1570 Once a flight record is selected, the flight monitor interface
1571 is displayed and the flight is re-enacted in real time. Check
1572 the Monitor Flight chapter above to learn how this window operates.
1576 <title>Graph Data</title>
1578 Select this button and you are prompted to select a flight
1579 record file, either a .telem file recording telemetry data or a
1580 .eeprom file containing flight data saved from
1584 Once a flight record is selected, a window with four tabs is
1585 opened. The first tab contains a graph with acceleration
1586 (blue), velocity (green) and altitude (red) of the flight,
1587 measured in metric units. The apogee(yellow) and main(magenta)
1588 igniter voltages are also displayed; high voltages indicate
1589 continuity, low voltages indicate open circuits. The second
1590 tab lets you configure which data to show in the graph. The
1591 third contains some basic flight statistics while the fourth
1592 has a map with the ground track of the flight displayed.
1595 The graph can be zoomed into a particular area by clicking and
1596 dragging down and to the right. Once zoomed, the graph can be
1597 reset by clicking and dragging up and to the left. Holding down
1598 control and clicking and dragging allows the graph to be panned.
1599 The right mouse button causes a pop-up menu to be displayed, giving
1600 you the option save or print the plot.
1603 Note that telemetry files will generally produce poor graphs
1604 due to the lower sampling rate and missed telemetry packets.
1605 Use saved flight data in .eeprom files for graphing where possible.
1609 <title>Export Data</title>
1611 This tool takes the raw data files and makes them available for
1612 external analysis. When you select this button, you are prompted to
1614 data file (either .eeprom or .telem will do, remember that
1615 .eeprom files contain higher resolution and more continuous
1616 data). Next, a second dialog appears which is used to select
1617 where to write the resulting file. It has a selector to choose
1618 between CSV and KML file formats.
1621 <title>Comma Separated Value Format</title>
1623 This is a text file containing the data in a form suitable for
1624 import into a spreadsheet or other external data analysis
1625 tool. The first few lines of the file contain the version and
1626 configuration information from the altimeter, then
1627 there is a single header line which labels all of the
1628 fields. All of these lines start with a '#' character which
1629 many tools can be configured to skip over.
1632 The remaining lines of the file contain the data, with each
1633 field separated by a comma and at least one space. All of
1634 the sensor values are converted to standard units, with the
1635 barometric data reported in both pressure, altitude and
1636 height above pad units.
1640 <title>Keyhole Markup Language (for Google Earth)</title>
1642 This is the format used by Google Earth to provide an overlay
1643 within that application. With this, you can use Google Earth to
1644 see the whole flight path in 3D.
1649 <title>Configure Altimeter</title>
1651 Select this button and then select either a TeleMetrum or
1652 TeleDongle Device from the list provided. Selecting a TeleDongle
1653 device will use the radio link to configure a remote altimeter.
1656 The first few lines of the dialog provide information about the
1657 connected device, including the product name,
1658 software version and hardware serial number. Below that are the
1659 individual configuration entries.
1662 At the bottom of the dialog, there are four buttons:
1667 Save. This writes any changes to the
1668 configuration parameter block in flash memory. If you don't
1669 press this button, any changes you make will be lost.
1674 Reset. This resets the dialog to the most recently saved values,
1675 erasing any changes you have made.
1680 Reboot. This reboots the device. Use this to
1681 switch from idle to pad mode by rebooting once the rocket is
1682 oriented for flight, or to confirm changes you think you saved
1688 Close. This closes the dialog. Any unsaved changes will be
1694 The rest of the dialog contains the parameters to be configured.
1697 <title>Main Deploy Altitude</title>
1699 This sets the altitude (above the recorded pad altitude) at
1700 which the 'main' igniter will fire. The drop-down menu shows
1701 some common values, but you can edit the text directly and
1702 choose whatever you like. If the apogee charge fires below
1703 this altitude, then the main charge will fire two seconds
1704 after the apogee charge fires.
1708 <title>Apogee Delay</title>
1710 When flying redundant electronics, it's often important to
1711 ensure that multiple apogee charges don't fire at precisely
1712 the same time, as that can over pressurize the apogee deployment
1713 bay and cause a structural failure of the air-frame. The Apogee
1714 Delay parameter tells the flight computer to fire the apogee
1715 charge a certain number of seconds after apogee has been
1720 <title>Radio Frequency</title>
1722 This configures which of the configured frequencies to use for both
1723 telemetry and packet command mode. Note that if you set this
1724 value via packet command mode, you will have to reconfigure
1725 the TeleDongle frequency before you will be able to use packet
1730 <title>Radio Calibration</title>
1732 The radios in every Altus Metrum device are calibrated at the
1733 factory to ensure that they transmit and receive on the
1734 specified frequency. If you need to you can adjust the calibration
1735 by changing this value. Do not do this without understanding what
1736 the value means, read the appendix on calibration and/or the source
1737 code for more information. To change a TeleDongle's calibration,
1738 you must reprogram the unit completely.
1742 <title>Callsign</title>
1744 This sets the call sign included in each telemetry packet. Set this
1745 as needed to conform to your local radio regulations.
1749 <title>Maximum Flight Log Size</title>
1751 This sets the space (in kilobytes) allocated for each flight
1752 log. The available space will be divided into chunks of this
1753 size. A smaller value will allow more flights to be stored,
1754 a larger value will record data from longer flights.
1758 <title>Ignite Mode</title>
1760 TeleMetrum and TeleMini provide two igniter channels as they
1761 were originally designed as dual-deploy flight
1762 computers. This configuration parameter allows the two
1763 channels to be used in different configurations.
1768 Dual Deploy. This is the usual mode of operation; the
1769 'apogee' channel is fired at apogee and the 'main'
1770 channel at the height above ground specified by the
1771 'Main Deploy Altitude' during descent.
1776 Redundant Apogee. This fires both channels at
1777 apogee, the 'apogee' channel first followed after a two second
1778 delay by the 'main' channel.
1783 Redundant Main. This fires both channels at the
1784 height above ground specified by the Main Deploy
1785 Altitude setting during descent. The 'apogee'
1786 channel is fired first, followed after a two second
1787 delay by the 'main' channel.
1793 <title>Pad Orientation</title>
1795 Because it includes an accelerometer, TeleMetrum is
1796 sensitive to the orientation of the board. By default, it
1797 expects the antenna end to point forward. This parameter
1798 allows that default to be changed, permitting the board to
1799 be mounted with the antenna pointing aft instead.
1804 Antenna Up. In this mode, the antenna end of the
1805 TeleMetrum board must point forward, in line with the
1806 expected flight path.
1811 Antenna Down. In this mode, the antenna end of the
1812 TeleMetrum board must point aft, in line with the
1813 expected flight path.
1820 <title>Configure AltosUI</title>
1822 This button presents a dialog so that you can configure the AltosUI global settings.
1825 <title>Voice Settings</title>
1827 AltosUI provides voice announcements during flight so that you
1828 can keep your eyes on the sky and still get information about
1829 the current flight status. However, sometimes you don't want
1834 <para>Enable—turns all voice announcements on and off</para>
1838 Test Voice—Plays a short message allowing you to verify
1839 that the audio system is working and the volume settings
1846 <title>Log Directory</title>
1848 AltosUI logs all telemetry data and saves all TeleMetrum flash
1849 data to this directory. This directory is also used as the
1850 staring point when selecting data files for display or export.
1853 Click on the directory name to bring up a directory choosing
1854 dialog, select a new directory and click 'Select Directory' to
1855 change where AltosUI reads and writes data files.
1859 <title>Callsign</title>
1861 This value is transmitted in each command packet sent from
1862 TeleDongle and received from an altimeter. It is not used in
1863 telemetry mode, as the callsign configured in the altimeter board
1864 is included in all telemetry packets. Configure this
1865 with the AltosUI operators call sign as needed to comply with
1866 your local radio regulations.
1869 Note that to successfully command a flight computer over the radio
1870 (to configure the altimeter, monitor idle, or fire pyro charges),
1871 the callsign configured here must exactly match the callsign
1872 configured in the flight computer. This matching is case
1877 <title>Imperial Units</title>
1879 This switches between metric units (meters) and imperial
1880 units (feet and miles). This affects the display of values
1881 use during flight monitoring, data graphing and all of the
1882 voice announcements. It does not change the units used when
1883 exporting to CSV files, those are always produced in metric units.
1887 <title>Font Size</title>
1889 Selects the set of fonts used in the flight monitor
1890 window. Choose between the small, medium and large sets.
1894 <title>Serial Debug</title>
1896 This causes all communication with a connected device to be
1897 dumped to the console from which AltosUI was started. If
1898 you've started it from an icon or menu entry, the output
1899 will simply be discarded. This mode can be useful to debug
1900 various serial communication issues.
1904 <title>Manage Frequencies</title>
1906 This brings up a dialog where you can configure the set of
1907 frequencies shown in the various frequency menus. You can
1908 add as many as you like, or even reconfigure the default
1909 set. Changing this list does not affect the frequency
1910 settings of any devices, it only changes the set of
1911 frequencies shown in the menus.
1916 <title>Configure Groundstation</title>
1918 Select this button and then select a TeleDongle Device from the list provided.
1921 The first few lines of the dialog provide information about the
1922 connected device, including the product name,
1923 software version and hardware serial number. Below that are the
1924 individual configuration entries.
1927 Note that the TeleDongle itself doesn't save any configuration
1928 data, the settings here are recorded on the local machine in
1929 the Java preferences database. Moving the TeleDongle to
1930 another machine, or using a different user account on the same
1931 machine will cause settings made here to have no effect.
1934 At the bottom of the dialog, there are three buttons:
1939 Save. This writes any changes to the
1940 local Java preferences file. If you don't
1941 press this button, any changes you make will be lost.
1946 Reset. This resets the dialog to the most recently saved values,
1947 erasing any changes you have made.
1952 Close. This closes the dialog. Any unsaved changes will be
1958 The rest of the dialog contains the parameters to be configured.
1961 <title>Frequency</title>
1963 This configures the frequency to use for both telemetry and
1964 packet command mode. Set this before starting any operation
1965 involving packet command mode so that it will use the right
1966 frequency. Telemetry monitoring mode also provides a menu to
1967 change the frequency, and that menu also sets the same Java
1968 preference value used here.
1972 <title>Radio Calibration</title>
1974 The radios in every Altus Metrum device are calibrated at the
1975 factory to ensure that they transmit and receive on the
1976 specified frequency. To change a TeleDongle's calibration,
1977 you must reprogram the unit completely, so this entry simply
1978 shows the current value and doesn't allow any changes.
1983 <title>Flash Image</title>
1985 This reprograms any Altus Metrum device by using a TeleMetrum
1986 or TeleDongle as a programming dongle. Please read the
1987 directions for flashing devices in the Updating Device
1988 Firmware chapter below.
1991 Once you have the programmer and target devices connected,
1992 push the 'Flash Image' button. That will present a dialog box
1993 listing all of the connected devices. Carefully select the
1994 programmer device, not the device to be programmed.
1997 Next, select the image to flash to the device. These are named
1998 with the product name and firmware version. The file selector
1999 will start in the directory containing the firmware included
2000 with the AltosUI package. Navigate to the directory containing
2001 the desired firmware if it isn't there.
2004 Next, a small dialog containing the device serial number and
2005 RF calibration values should appear. If these values are
2006 incorrect (possibly due to a corrupted image in the device),
2007 enter the correct values here.
2010 Finally, a dialog containing a progress bar will follow the
2011 programming process.
2014 When programming is complete, the target device will
2015 reboot. Note that if the target device is connected via USB, you
2016 will have to unplug it and then plug it back in for the USB
2017 connection to reset so that you can communicate with the device
2022 <title>Fire Igniter</title>
2024 This activates the igniter circuits in TeleMetrum to help test
2025 recovery systems deployment. Because this command can operate
2026 over the Packet Command Link, you can prepare the rocket as
2027 for flight and then test the recovery system without needing
2028 to snake wires inside the air-frame.
2031 Selecting the 'Fire Igniter' button brings up the usual device
2032 selection dialog. Pick the desired TeleDongle or TeleMetrum
2033 device. This brings up another window which shows the current
2034 continuity test status for both apogee and main charges.
2037 Next, select the desired igniter to fire. This will enable the
2041 Select the 'Arm' button. This enables the 'Fire' button. The
2042 word 'Arm' is replaced by a countdown timer indicating that
2043 you have 10 seconds to press the 'Fire' button or the system
2044 will deactivate, at which point you start over again at
2045 selecting the desired igniter.
2049 <title>Scan Channels</title>
2051 This listens for telemetry packets on all of the configured
2052 frequencies, displaying information about each device it
2053 receives a packet from. You can select which of the three
2054 telemetry formats should be tried; by default, it only listens
2055 for the standard telemetry packets used in v1.0 and later
2060 <title>Load Maps</title>
2062 Before heading out to a new launch site, you can use this to
2063 load satellite images in case you don't have internet
2064 connectivity at the site. This loads a fairly large area
2065 around the launch site, which should cover any flight you're likely to make.
2068 There's a drop-down menu of launch sites we know about; if
2069 your favorites aren't there, please let us know the lat/lon
2070 and name of the site. The contents of this list are actually
2071 downloaded at run-time, so as new sites are sent in, they'll
2072 get automatically added to this list.
2075 If the launch site isn't in the list, you can manually enter the lat/lon values
2078 Clicking the 'Load Map' button will fetch images from Google
2079 Maps; note that Google limits how many images you can fetch at
2080 once, so if you load more than one launch site, you may get
2081 some gray areas in the map which indicate that Google is tired
2082 of sending data to you. Try again later.
2086 <title>Monitor Idle</title>
2088 This brings up a dialog similar to the Monitor Flight UI,
2089 except it works with the altimeter in "idle" mode by sending
2090 query commands to discover the current state rather than
2091 listening for telemetry packets.
2096 <title>AltosDroid</title>
2098 AltosDroid provides the same flight monitoring capabilities as
2099 AltosUI, but runs on Android devices and is designed to connect
2100 to a TeleBT receiver over Bluetooth™. Altos Droid monitors
2101 telemetry data, logging it to internal storage in the Android
2102 device, and presents that data in a UI the same way the 'Monitor
2103 Flight' window does in AltosUI.
2106 This manual will explain how to configure AltosDroid, connect
2107 to TeleBT, operate the flight monitoring interface and describe
2108 what the displayed data means.
2111 <title>Installing AltosDroid</title>
2113 AltosDroid is included in the Google Play store. To install
2114 it on your Android device, open open the Google Play Store
2115 application and search for "altosdroid". Make sure you don't
2116 have a space between "altos" and "droid" or you probably won't
2117 find what you want. That should bring you to the right page
2118 from which you can download and install the application.
2122 <title>Connecting to TeleBT</title>
2124 Press the Android 'Menu' button or soft-key to see the
2125 configuration options available. Select the 'Connect a device'
2126 option and then the 'Scan for devices' entry at the bottom to
2127 look for your TeleBT device. Select your device, and when it
2128 asks for the code, enter '1234'.
2131 Subsequent connections will not require you to enter that
2132 code, and your 'paired' device will appear in the list without
2137 <title>Configuring AltosDroid</title>
2139 The only configuration option available for AltosDroid is
2140 which frequency to listen on. Press the Android 'Menu' button
2141 or soft-key and pick the 'Select radio frequency' entry. That
2142 brings up a menu of pre-set radio frequencies; pick the one
2143 which matches your altimeter.
2147 <title>Altos Droid Flight Monitoring</title>
2149 Altos Droid is designed to mimic the AltosUI flight monitoring
2150 display, providing separate tabs for each stage of your rocket
2151 flight along with a tab containing a map of the local area
2152 with icons marking the current location of the altimeter and
2158 The 'Launch Pad' tab shows information used to decide when the
2159 rocket is ready for flight. The first elements include red/green
2160 indicators, if any of these is red, you'll want to evaluate
2161 whether the rocket is ready to launch:
2165 Battery Voltage. This indicates whether the Li-Po battery
2166 powering the TeleMetrum has sufficient charge to last for
2167 the duration of the flight. A value of more than
2168 3.7V is required for a 'GO' status.
2173 Apogee Igniter Voltage. This indicates whether the apogee
2174 igniter has continuity. If the igniter has a low
2175 resistance, then the voltage measured here will be close
2176 to the Li-Po battery voltage. A value greater than 3.2V is
2177 required for a 'GO' status.
2182 Main Igniter Voltage. This indicates whether the main
2183 igniter has continuity. If the igniter has a low
2184 resistance, then the voltage measured here will be close
2185 to the Li-Po battery voltage. A value greater than 3.2V is
2186 required for a 'GO' status.
2191 On-board Data Logging. This indicates whether there is
2192 space remaining on-board to store flight data for the
2193 upcoming flight. If you've downloaded data, but failed
2194 to erase flights, there may not be any space
2195 left. TeleMetrum can store multiple flights, depending
2196 on the configured maximum flight log size. TeleMini
2197 stores only a single flight, so it will need to be
2198 downloaded and erased after each flight to capture
2199 data. This only affects on-board flight logging; the
2200 altimeter will still transmit telemetry and fire
2201 ejection charges at the proper times.
2206 GPS Locked. For a TeleMetrum device, this indicates whether the GPS receiver is
2207 currently able to compute position information. GPS requires
2208 at least 4 satellites to compute an accurate position.
2213 GPS Ready. For a TeleMetrum device, this indicates whether GPS has reported at least
2214 10 consecutive positions without losing lock. This ensures
2215 that the GPS receiver has reliable reception from the
2222 The Launchpad tab also shows the computed launch pad position
2223 and altitude, averaging many reported positions to improve the
2224 accuracy of the fix.
2229 <title>Downloading Flight Logs</title>
2231 Altos Droid always saves every bit of telemetry data it
2232 receives. To download that to a computer for use with AltosUI,
2233 simply remove the SD card from your Android device, or connect
2234 your device to your computer's USB port and browse the files
2235 on that device. You will find '.telem' files in the TeleMetrum
2236 directory that will work with AltosUI directly.
2241 <title>Using Altus Metrum Products</title>
2243 <title>Being Legal</title>
2245 First off, in the US, you need an <ulink url="http://www.altusmetrum.org/Radio/">amateur radio license</ulink> or
2246 other authorization to legally operate the radio transmitters that are part
2251 <title>In the Rocket</title>
2253 In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
2254 <ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
2255 a single-cell, 3.7 volt nominal Li-Po rechargeable battery. An
2256 850mAh battery weighs less than a 9V alkaline battery, and will
2257 run a TeleMetrum for hours.
2258 A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
2259 a few hours, or a TeleMini for much (much) longer.
2262 By default, we ship the altimeters with a simple wire antenna. If your
2263 electronics bay or the air-frame it resides within is made of carbon fiber,
2264 which is opaque to RF signals, you may choose to have an SMA connector
2265 installed so that you can run a coaxial cable to an antenna mounted
2266 elsewhere in the rocket.
2270 <title>On the Ground</title>
2272 To receive the data stream from the rocket, you need an antenna and short
2273 feed-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. If possible, use an SMA to BNC
2274 adapter instead of feedline between the antenna feedpoint and
2275 TeleDongle, as this will give you the best performance. The
2276 TeleDongle in turn plugs directly into the USB port on a notebook
2277 computer. Because TeleDongle looks like a simple serial port, your computer
2278 does not require special device drivers... just plug it in.
2281 The GUI tool, AltosUI, is written in Java and runs across
2282 Linux, Mac OS and Windows. There's also a suite of C tools
2283 for Linux which can perform most of the same tasks.
2286 After the flight, you can use the radio link to extract the more detailed data
2287 logged in either TeleMetrum or TeleMini devices, or you can use a mini USB cable to plug into the
2288 TeleMetrum board directly. Pulling out the data without having to open up
2289 the rocket is pretty cool! A USB cable is also how you charge the Li-Po
2290 battery, so you'll want one of those anyway... the same cable used by lots
2291 of digital cameras and other modern electronic stuff will work fine.
2294 If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
2295 receiver, so that you can put in a way-point for the last reported rocket
2296 position before touch-down. This makes looking for your rocket a lot like
2297 Geo-Caching... just go to the way-point and look around starting from there.
2300 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
2301 can use that with your antenna to direction-find the rocket on the ground
2302 the same way you can use a Walston or Beeline tracker. This can be handy
2303 if the rocket is hiding in sage brush or a tree, or if the last GPS position
2304 doesn't get you close enough because the rocket dropped into a canyon, or
2305 the wind is blowing it across a dry lake bed, or something like that... Keith
2306 and Bdale both currently own and use the Yaesu VX-7R at launches.
2309 So, to recap, on the ground the hardware you'll need includes:
2310 <orderedlist inheritnum='inherit' numeration='arabic'>
2313 an antenna and feed-line or adapter
2328 optionally, a hand-held GPS receiver
2333 optionally, an HT or receiver covering 435 MHz
2339 The best hand-held commercial directional antennas we've found for radio
2340 direction finding rockets are from
2341 <ulink url="http://www.arrowantennas.com/" >
2344 The 440-3 and 440-5 are both good choices for finding a
2345 TeleMetrum- or TeleMini- equipped rocket when used with a suitable
2346 70cm HT. TeleDongle and an SMA to BNC adapter fit perfectly
2347 between the driven element and reflector of Arrow antennas.
2351 <title>Data Analysis</title>
2353 Our software makes it easy to log the data from each flight, both the
2354 telemetry received during the flight itself, and the more
2355 complete data log recorded in the flash memory on the altimeter
2356 board. Once this data is on your computer, our post-flight tools make it
2357 easy to quickly get to the numbers everyone wants, like apogee altitude,
2358 max acceleration, and max velocity. You can also generate and view a
2359 standard set of plots showing the altitude, acceleration, and
2360 velocity of the rocket during flight. And you can even export a TeleMetrum data file
2361 usable with Google Maps and Google Earth for visualizing the flight path
2362 in two or three dimensions!
2365 Our ultimate goal is to emit a set of files for each flight that can be
2366 published as a web page per flight, or just viewed on your local disk with
2371 <title>Future Plans</title>
2373 In the future, we intend to offer "companion boards" for the rocket
2374 that will plug in to TeleMetrum to collect additional data, provide
2375 more pyro channels, and so forth.
2378 Also under design is a new flight computer with more sensors, more
2379 pyro channels, and a more powerful radio system designed for use
2380 in multi-stage, complex, and extreme altitude projects.
2383 We are also working on alternatives to TeleDongle. One is a
2384 a stand-alone, hand-held ground terminal that will allow monitoring
2385 the rocket's status, collecting data during flight, and logging data
2386 after flight without the need for a notebook computer on the
2387 flight line. Particularly since it is so difficult to read most
2388 notebook screens in direct sunlight, we think this will be a great
2389 thing to have. We are also working on a TeleDongle variant with
2390 Bluetooth that will work with Android phones and tablets.
2393 Because all of our work is open, both the hardware designs and the
2394 software, if you have some great idea for an addition to the current
2395 Altus Metrum family, feel free to dive in and help! Or let us know
2396 what you'd like to see that we aren't already working on, and maybe
2397 we'll get excited about it too...
2401 <ulink url="http://altusmetrum.org/">web site</ulink> for more news
2402 and information as our family of products evolves!
2407 <title>Altimeter Installation Recommendations</title>
2409 Building high-power rockets that fly safely is hard enough. Mix
2410 in some sophisticated electronics and a bunch of radio energy
2411 and oftentimes you find few perfect solutions. This chapter
2412 contains some suggestions about how to install Altus Metrum
2413 products into the rocket air-frame, including how to safely and
2414 reliably mix a variety of electronics into the same air-frame.
2417 <title>Mounting the Altimeter</title>
2419 The first consideration is to ensure that the altimeter is
2420 securely fastened to the air-frame. For TeleMetrum, we use
2421 nylon standoffs and nylon screws; they're good to at least 50G
2422 and cannot cause any electrical issues on the board. For
2423 TeleMini, we usually cut small pieces of 1/16" balsa to fit
2424 under the screw holes, and then take 2x56 nylon screws and
2425 screw them through the TeleMini mounting holes, through the
2426 balsa and into the underlying material.
2428 <orderedlist inheritnum='inherit' numeration='arabic'>
2431 Make sure TeleMetrum is aligned precisely along the axis of
2432 acceleration so that the accelerometer can accurately
2433 capture data during the flight.
2438 Watch for any metal touching components on the
2439 board. Shorting out connections on the bottom of the board
2440 can cause the altimeter to fail during flight.
2446 <title>Dealing with the Antenna</title>
2448 The antenna supplied is just a piece of solid, insulated,
2449 wire. If it gets damaged or broken, it can be easily
2450 replaced. It should be kept straight and not cut; bending or
2451 cutting it will change the resonant frequency and/or
2452 impedance, making it a less efficient radiator and thus
2453 reducing the range of the telemetry signal.
2456 Keeping metal away from the antenna will provide better range
2457 and a more even radiation pattern. In most rockets, it's not
2458 entirely possible to isolate the antenna from metal
2459 components; there are often bolts, all-thread and wires from other
2460 electronics to contend with. Just be aware that the more stuff
2461 like this around the antenna, the lower the range.
2464 Make sure the antenna is not inside a tube made or covered
2465 with conducting material. Carbon fiber is the most common
2466 culprit here -- CF is a good conductor and will effectively
2467 shield the antenna, dramatically reducing signal strength and
2468 range. Metallic flake paint is another effective shielding
2469 material which is to be avoided around any antennas.
2472 If the ebay is large enough, it can be convenient to simply
2473 mount the altimeter at one end and stretch the antenna out
2474 inside. Taping the antenna to the sled can keep it straight
2475 under acceleration. If there are metal rods, keep the
2476 antenna as far away as possible.
2479 For a shorter ebay, it's quite practical to have the antenna
2480 run through a bulkhead and into an adjacent bay. Drill a small
2481 hole in the bulkhead, pass the antenna wire through it and
2482 then seal it up with glue or clay. We've also used acrylic
2483 tubing to create a cavity for the antenna wire. This works a
2484 bit better in that the antenna is known to stay straight and
2485 not get folded by recovery components in the bay. Angle the
2486 tubing towards the side wall of the rocket and it ends up
2487 consuming very little space.
2490 If you need to place the antenna at a distance from the
2491 altimeter, you can replace the antenna with an edge-mounted
2492 SMA connector, and then run 50Ω coax from the board to the
2493 antenna. Building a remote antenna is beyond the scope of this
2498 <title>Preserving GPS Reception</title>
2500 The GPS antenna and receiver in TeleMetrum are highly
2501 sensitive and normally have no trouble tracking enough
2502 satellites to provide accurate position information for
2503 recovering the rocket. However, there are many ways to
2504 attenuate the GPS signal.
2505 <orderedlist inheritnum='inherit' numeration='arabic'>
2508 Conductive tubing or coatings. Carbon fiber and metal
2509 tubing, or metallic paint will all dramatically attenuate the
2510 GPS signal. We've never heard of anyone successfully
2511 receiving GPS from inside these materials.
2516 Metal components near the GPS patch antenna. These will
2517 de-tune the patch antenna, changing the resonant frequency
2518 away from the L1 carrier and reduce the effectiveness of the
2519 antenna. You can place as much stuff as you like beneath the
2520 antenna as that's covered with a ground plane. But, keep
2521 wires and metal out from above the patch antenna.
2528 <title>Radio Frequency Interference</title>
2530 Any altimeter will generate RFI; the digital circuits use
2531 high-frequency clocks that spray radio interference across a
2532 wide band. Altus Metrum altimeters generate intentional radio
2533 signals as well, increasing the amount of RF energy around the board.
2536 Rocketry altimeters also use precise sensors measuring air
2537 pressure and acceleration. Tiny changes in voltage can cause
2538 these sensor readings to vary by a huge amount. When the
2539 sensors start mis-reporting data, the altimeter can either
2540 fire the igniters at the wrong time, or not fire them at all.
2543 Voltages are induced when radio frequency energy is
2544 transmitted from one circuit to another. Here are things that
2545 influence the induced voltage and current:
2550 Keep wires from different circuits apart. Moving circuits
2551 further apart will reduce RFI.
2556 Avoid parallel wires from different circuits. The longer two
2557 wires run parallel to one another, the larger the amount of
2558 transferred energy. Cross wires at right angles to reduce
2564 Twist wires from the same circuits. Two wires the same
2565 distance from the transmitter will get the same amount of
2566 induced energy which will then cancel out. Any time you have
2567 a wire pair running together, twist the pair together to
2568 even out distances and reduce RFI. For altimeters, this
2569 includes battery leads, switch hookups and igniter
2575 Avoid resonant lengths. Know what frequencies are present
2576 in the environment and avoid having wire lengths near a
2577 natural resonant length. Altusmetrum products transmit on the
2578 70cm amateur band, so you should avoid lengths that are a
2579 simple ratio of that length; essentially any multiple of 1/4
2580 of the wavelength (17.5cm).
2586 <title>The Barometric Sensor</title>
2588 Altusmetrum altimeters measure altitude with a barometric
2589 sensor, essentially measuring the amount of air above the
2590 rocket to figure out how high it is. A large number of
2591 measurements are taken as the altimeter initializes itself to
2592 figure out the pad altitude. Subsequent measurements are then
2593 used to compute the height above the pad.
2596 To accurately measure atmospheric pressure, the ebay
2597 containing the altimeter must be vented outside the
2598 air-frame. The vent must be placed in a region of linear
2599 airflow, have smooth edges, and away from areas of increasing or
2600 decreasing pressure.
2603 The barometric sensor in the altimeter is quite sensitive to
2604 chemical damage from the products of APCP or BP combustion, so
2605 make sure the ebay is carefully sealed from any compartment
2606 which contains ejection charges or motors.
2610 <title>Ground Testing</title>
2612 The most important aspect of any installation is careful
2613 ground testing. Bringing an air-frame up to the LCO table which
2614 hasn't been ground tested can lead to delays or ejection
2615 charges firing on the pad, or, even worse, a recovery system
2619 Do a 'full systems' test that includes wiring up all igniters
2620 without any BP and turning on all of the electronics in flight
2621 mode. This will catch any mistakes in wiring and any residual
2622 RFI issues that might accidentally fire igniters at the wrong
2623 time. Let the air-frame sit for several minutes, checking for
2624 adequate telemetry signal strength and GPS lock. If any igniters
2625 fire unexpectedly, find and resolve the issue before loading any
2629 Ground test the ejection charges. Prepare the rocket for
2630 flight, loading ejection charges and igniters. Completely
2631 assemble the air-frame and then use the 'Fire Igniters'
2632 interface through a TeleDongle to command each charge to
2633 fire. Make sure the charge is sufficient to robustly separate
2634 the air-frame and deploy the recovery system.
2639 <title>Updating Device Firmware</title>
2641 The big concept to understand is that you have to use a
2642 TeleDongle as a programmer to update a TeleMetrum or TeleMini,
2643 and a TeleMetrum or other TeleDongle to program the TeleDongle
2644 Due to limited memory resources in the cc1111, we don't support
2645 programming directly over USB.
2648 You may wish to begin by ensuring you have current firmware images.
2649 These are distributed as part of the AltOS software bundle that
2650 also includes the AltosUI ground station program. Newer ground
2651 station versions typically work fine with older firmware versions,
2652 so you don't need to update your devices just to try out new
2653 software features. You can always download the most recent
2654 version from <ulink url="http://www.altusmetrum.org/AltOS/"/>.
2657 We recommend updating the altimeter first, before updating TeleDongle.
2660 <title>Updating TeleMetrum Firmware</title>
2661 <orderedlist inheritnum='inherit' numeration='arabic'>
2664 Find the 'programming cable' that you got as part of the starter
2665 kit, that has a red 8-pin MicroMaTch connector on one end and a
2666 red 4-pin MicroMaTch connector on the other end.
2671 Take the 2 screws out of the TeleDongle case to get access
2672 to the circuit board.
2677 Plug the 8-pin end of the programming cable to the
2678 matching connector on the TeleDongle, and the 4-pin end to the
2679 matching connector on the TeleMetrum.
2680 Note that each MicroMaTch connector has an alignment pin that
2681 goes through a hole in the PC board when you have the cable
2687 Attach a battery to the TeleMetrum board.
2692 Plug the TeleDongle into your computer's USB port, and power
2698 Run AltosUI, and select 'Flash Image' from the File menu.
2703 Pick the TeleDongle device from the list, identifying it as the
2709 Select the image you want put on the TeleMetrum, which should have a
2710 name in the form telemetrum-v1.2-1.0.0.ihx. It should be visible
2711 in the default directory, if not you may have to poke around
2712 your system to find it.
2717 Make sure the configuration parameters are reasonable
2718 looking. If the serial number and/or RF configuration
2719 values aren't right, you'll need to change them.
2724 Hit the 'OK' button and the software should proceed to flash
2725 the TeleMetrum with new firmware, showing a progress bar.
2730 Confirm that the TeleMetrum board seems to have updated OK, which you
2731 can do by plugging in to it over USB and using a terminal program
2732 to connect to the board and issue the 'v' command to check
2738 If something goes wrong, give it another try.
2744 <title>Updating TeleMini Firmware</title>
2745 <orderedlist inheritnum='inherit' numeration='arabic'>
2748 You'll need a special 'programming cable' to reprogram the
2749 TeleMini. It's available on the Altus Metrum web store, or
2750 you can make your own using an 8-pin MicroMaTch connector on
2751 one end and a set of four pins on the other.
2756 Take the 2 screws out of the TeleDongle case to get access
2757 to the circuit board.
2762 Plug the 8-pin end of the programming cable to the matching
2763 connector on the TeleDongle, and the 4-pins into the holes
2764 in the TeleMini circuit board. Note that the MicroMaTch
2765 connector has an alignment pin that goes through a hole in
2766 the PC board when you have the cable oriented correctly, and
2767 that pin 1 on the TeleMini board is marked with a square pad
2768 while the other pins have round pads.
2773 Attach a battery to the TeleMini board.
2778 Plug the TeleDongle into your computer's USB port, and power
2784 Run AltosUI, and select 'Flash Image' from the File menu.
2789 Pick the TeleDongle device from the list, identifying it as the
2795 Select the image you want put on the TeleMini, which should have a
2796 name in the form telemini-v1.0-1.0.0.ihx. It should be visible
2797 in the default directory, if not you may have to poke around
2798 your system to find it.
2803 Make sure the configuration parameters are reasonable
2804 looking. If the serial number and/or RF configuration
2805 values aren't right, you'll need to change them.
2810 Hit the 'OK' button and the software should proceed to flash
2811 the TeleMini with new firmware, showing a progress bar.
2816 Confirm that the TeleMini board seems to have updated OK, which you
2817 can do by configuring it over the radio link through the TeleDongle, or
2818 letting it come up in "flight" mode and listening for telemetry.
2823 If something goes wrong, give it another try.
2829 <title>Updating TeleDongle Firmware</title>
2831 Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
2832 firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
2834 <orderedlist inheritnum='inherit' numeration='arabic'>
2837 Find the 'programming cable' that you got as part of the starter
2838 kit, that has a red 8-pin MicroMaTch connector on one end and a
2839 red 4-pin MicroMaTch connector on the other end.
2844 Find the USB cable that you got as part of the starter kit, and
2845 plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
2850 Take the 2 screws out of the TeleDongle case to get access
2851 to the circuit board.
2856 Plug the 8-pin end of the programming cable to the
2857 matching connector on the programmer, and the 4-pin end to the
2858 matching connector on the TeleDongle.
2859 Note that each MicroMaTch connector has an alignment pin that
2860 goes through a hole in the PC board when you have the cable
2866 Attach a battery to the TeleMetrum board if you're using one.
2871 Plug both the programmer and the TeleDongle into your computer's USB
2872 ports, and power up the programmer.
2877 Run AltosUI, and select 'Flash Image' from the File menu.
2882 Pick the programmer device from the list, identifying it as the
2888 Select the image you want put on the TeleDongle, which should have a
2889 name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
2890 in the default directory, if not you may have to poke around
2891 your system to find it.
2896 Make sure the configuration parameters are reasonable
2897 looking. If the serial number and/or RF configuration
2898 values aren't right, you'll need to change them. The TeleDongle
2899 serial number is on the "bottom" of the circuit board, and can
2900 usually be read through the translucent blue plastic case without
2901 needing to remove the board from the case.
2906 Hit the 'OK' button and the software should proceed to flash
2907 the TeleDongle with new firmware, showing a progress bar.
2912 Confirm that the TeleDongle board seems to have updated OK, which you
2913 can do by plugging in to it over USB and using a terminal program
2914 to connect to the board and issue the 'v' command to check
2915 the version, etc. Once you're happy, remove the programming cable
2916 and put the cover back on the TeleDongle.
2921 If something goes wrong, give it another try.
2926 Be careful removing the programming cable from the locking 8-pin
2927 connector on TeleMetrum. You'll need a fingernail or perhaps a thin
2928 screwdriver or knife blade to gently pry the locking ears out
2929 slightly to extract the connector. We used a locking connector on
2930 TeleMetrum to help ensure that the cabling to companion boards
2931 used in a rocket don't ever come loose accidentally in flight.
2936 <title>Hardware Specifications</title>
2938 <title>TeleMetrum Specifications</title>
2942 Recording altimeter for model rocketry.
2947 Supports dual deployment (can fire 2 ejection charges).
2952 70cm ham-band transceiver for telemetry down-link.
2957 Barometric pressure sensor good to 45k feet MSL.
2962 1-axis high-g accelerometer for motor characterization, capable of
2963 +/- 50g using default part.
2968 On-board, integrated GPS receiver with 5Hz update rate capability.
2973 On-board 1 megabyte non-volatile memory for flight data storage.
2978 USB interface for battery charging, configuration, and data recovery.
2983 Fully integrated support for Li-Po rechargeable batteries.
2988 Uses Li-Po to fire e-matches, can be modified to support
2989 optional separate pyro battery if needed.
2994 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
3000 <title>TeleMini Specifications</title>
3004 Recording altimeter for model rocketry.
3009 Supports dual deployment (can fire 2 ejection charges).
3014 70cm ham-band transceiver for telemetry down-link.
3019 Barometric pressure sensor good to 45k feet MSL.
3024 On-board 5 kilobyte non-volatile memory for flight data storage.
3029 RF interface for configuration, and data recovery.
3034 Support for Li-Po rechargeable batteries, using an external charger.
3039 Uses Li-Po to fire e-matches, can be modified to support
3040 optional separate pyro battery if needed.
3045 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
3054 TeleMetrum seems to shut off when disconnected from the
3055 computer. Make sure the battery is adequately charged. Remember the
3056 unit will pull more power than the USB port can deliver before the
3057 GPS enters "locked" mode. The battery charges best when TeleMetrum
3061 It's impossible to stop the TeleDongle when it's in "p" mode, I have
3062 to unplug the USB cable? Make sure you have tried to "escape out" of
3063 this mode. If this doesn't work the reboot procedure for the
3064 TeleDongle *is* to simply unplug it. 'cu' however will retain it's
3065 outgoing buffer IF your "escape out" ('~~') does not work.
3066 At this point using either 'ao-view' (or possibly
3067 'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
3071 The amber LED (on the TeleMetrum) lights up when both
3072 battery and USB are connected. Does this mean it's charging?
3073 Yes, the yellow LED indicates the charging at the 'regular' rate.
3074 If the led is out but the unit is still plugged into a USB port,
3075 then the battery is being charged at a 'trickle' rate.
3078 There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
3079 That's the "pad" mode. Weak batteries might be the problem.
3080 It is also possible that the TeleMetrum is horizontal and the output
3081 is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
3082 it received a command packet which would have left it in "pad" mode.
3085 How do I save flight data?
3086 Live telemetry is written to file(s) whenever AltosUI is connected
3087 to the TeleDongle. The file area defaults to ~/TeleMetrum
3088 but is easily changed using the menus in AltosUI. The files that
3089 are written end in '.telem'. The after-flight
3090 data-dumped files will end in .eeprom and represent continuous data
3091 unlike the .telem files that are subject to losses
3092 along the RF data path.
3093 See the above instructions on what and how to save the eeprom stored
3094 data after physically retrieving your altimeter. Make sure to save
3095 the on-board data after each flight; while the TeleMetrum can store
3096 multiple flights, you never know when you'll lose the altimeter...
3100 <title>Notes for Older Software</title>
3103 Before AltosUI was written, using Altus Metrum devices required
3104 some finesse with the Linux command line. There was a limited
3105 GUI tool, ao-view, which provided functionality similar to the
3106 Monitor Flight window in AltosUI, but everything else was a
3107 fairly 80's experience. This appendix includes documentation for
3108 using that software.
3112 Both TeleMetrum and TeleDongle can be directly communicated
3113 with using USB ports. The first thing you should try after getting
3114 both units plugged into to your computer's USB port(s) is to run
3115 'ao-list' from a terminal-window to see what port-device-name each
3116 device has been assigned by the operating system.
3117 You will need this information to access the devices via their
3118 respective on-board firmware and data using other command line
3119 programs in the AltOS software suite.
3122 TeleMini can be communicated with through a TeleDongle device
3123 over the radio link. When first booted, TeleMini listens for a
3124 TeleDongle device and if it receives a packet, it goes into
3125 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
3126 launched. The easiest way to get it talking is to start the
3127 communication link on the TeleDongle and the power up the
3131 To access the device's firmware for configuration you need a terminal
3132 program such as you would use to talk to a modem. The software
3133 authors prefer using the program 'cu' which comes from the UUCP package
3134 on most Unix-like systems such as Linux. An example command line for
3135 cu might be 'cu -l /dev/ttyACM0', substituting the correct number
3136 indicated from running the
3137 ao-list program. Another reasonable terminal program for Linux is
3138 'cutecom'. The default 'escape'
3139 character used by CU (i.e. the character you use to
3140 issue commands to cu itself instead of sending the command as input
3141 to the connected device) is a '~'. You will need this for use in
3142 only two different ways during normal operations. First is to exit
3143 the program by sending a '~.' which is called a 'escape-disconnect'
3144 and allows you to close-out from 'cu'. The
3145 second use will be outlined later.
3148 All of the Altus Metrum devices share the concept of a two level
3149 command set in their firmware.
3150 The first layer has several single letter commands. Once
3151 you are using 'cu' (or 'cutecom') sending (typing) a '?'
3152 returns a full list of these
3153 commands. The second level are configuration sub-commands accessed
3154 using the 'c' command, for
3155 instance typing 'c?' will give you this second level of commands
3156 (all of which require the
3157 letter 'c' to access). Please note that most configuration options
3158 are stored only in Flash memory; TeleDongle doesn't provide any storage
3159 for these options and so they'll all be lost when you unplug it.
3162 Try setting these configuration ('c' or second level menu) values. A good
3163 place to start is by setting your call sign. By default, the boards
3164 use 'N0CALL' which is cute, but not exactly legal!
3165 Spend a few minutes getting comfortable with the units, their
3166 firmware, and 'cu' (or possibly 'cutecom').
3167 For instance, try to send
3168 (type) a 'c r 2' and verify the channel change by sending a 'c s'.
3169 Verify you can connect and disconnect from the units while in your
3170 terminal program by sending the escape-disconnect mentioned above.
3173 To set the radio frequency, use the 'c R' command to specify the
3174 radio transceiver configuration parameter. This parameter is computed
3175 using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
3176 the standard calibration reference frequency, 'S', (normally 434.550MHz):
3180 Round the result to the nearest integer value.
3181 As with all 'c' sub-commands, follow this with a 'c w' to write the
3182 change to the parameter block in the on-board flash on
3183 your altimeter board if you want the change to stay in place across reboots.
3186 To set the apogee delay, use the 'c d' command.
3187 As with all 'c' sub-commands, follow this with a 'c w' to write the
3188 change to the parameter block in the on-board DataFlash chip.
3191 To set the main deployment altitude, use the 'c m' command.
3192 As with all 'c' sub-commands, follow this with a 'c w' to write the
3193 change to the parameter block in the on-board DataFlash chip.
3196 To calibrate the radio frequency, connect the UHF antenna port to a
3197 frequency counter, set the board to 434.550MHz, and use the 'C'
3198 command to generate a CW carrier. Wait for the transmitter temperature
3199 to stabilize and the frequency to settle down.
3200 Then, divide 434.550 MHz by the
3201 measured frequency and multiply by the current radio cal value show
3202 in the 'c s' command. For an unprogrammed board, the default value
3203 is 1186611. Take the resulting integer and program it using the 'c f'
3204 command. Testing with the 'C' command again should show a carrier
3205 within a few tens of Hertz of the intended frequency.
3206 As with all 'c' sub-commands, follow this with a 'c w' to write the
3207 change to the parameter block in the on-board DataFlash chip.
3210 Note that the 'reboot' command, which is very useful on the altimeters,
3211 will likely just cause problems with the dongle. The *correct* way
3212 to reset the dongle is just to unplug and re-plug it.
3215 A fun thing to do at the launch site and something you can do while
3216 learning how to use these units is to play with the radio link access
3217 between an altimeter and the TeleDongle. Be aware that you *must* create
3218 some physical separation between the devices, otherwise the link will
3219 not function due to signal overload in the receivers in each device.
3222 Now might be a good time to take a break and read the rest of this
3223 manual, particularly about the two "modes" that the altimeters
3224 can be placed in. TeleMetrum uses the position of the device when booting
3225 up will determine whether the unit is in "pad" or "idle" mode. TeleMini
3226 enters "idle" mode when it receives a command packet within the first 5 seconds
3227 of being powered up, otherwise it enters "pad" mode.
3230 You can access an altimeter in idle mode from the TeleDongle's USB
3231 connection using the radio link
3232 by issuing a 'p' command to the TeleDongle. Practice connecting and
3233 disconnecting ('~~' while using 'cu') from the altimeter. If
3234 you cannot escape out of the "p" command, (by using a '~~' when in
3235 CU) then it is likely that your kernel has issues. Try a newer version.
3238 Using this radio link allows you to configure the altimeter, test
3239 fire e-matches and igniters from the flight line, check pyro-match
3240 continuity and so forth. You can leave the unit turned on while it
3241 is in 'idle mode' and then place the
3242 rocket vertically on the launch pad, walk away and then issue a
3243 reboot command. The altimeter will reboot and start sending data
3244 having changed to the "pad" mode. If the TeleDongle is not receiving
3245 this data, you can disconnect 'cu' from the TeleDongle using the
3246 procedures mentioned above and THEN connect to the TeleDongle from
3247 inside 'ao-view'. If this doesn't work, disconnect from the
3248 TeleDongle, unplug it, and try again after plugging it back in.
3251 In order to reduce the chance of accidental firing of pyrotechnic
3252 charges, the command to fire a charge is intentionally somewhat
3253 difficult to type, and the built-in help is slightly cryptic to
3254 prevent accidental echoing of characters from the help text back at
3255 the board from firing a charge. The command to fire the apogee
3256 drogue charge is 'i DoIt drogue' and the command to fire the main
3257 charge is 'i DoIt main'.
3260 On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
3261 and 'ao-view' will both auditorily announce and visually indicate
3263 Now you can launch knowing that you have a good data path and
3264 good satellite lock for flight data and recovery. Remember
3265 you MUST tell ao-view to connect to the TeleDongle explicitly in
3266 order for ao-view to be able to receive data.
3269 The altimeters provide RDF (radio direction finding) tones on
3270 the pad, during descent and after landing. These can be used to
3271 locate the rocket using a directional antenna; the signal
3272 strength providing an indication of the direction from receiver to rocket.
3275 TeleMetrum also provides GPS tracking data, which can further simplify
3276 locating the rocket once it has landed. (The last good GPS data
3277 received before touch-down will be on the data screen of 'ao-view'.)
3280 Once you have recovered the rocket you can download the eeprom
3281 contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
3282 either a USB cable or over the radio link using TeleDongle.
3283 And by following the man page for 'ao-postflight' you can create
3284 various data output reports, graphs, and even KML data to see the
3285 flight trajectory in Google-earth. (Moving the viewing angle making
3286 sure to connect the yellow lines while in Google-earth is the proper
3290 As for ao-view.... some things are in the menu but don't do anything
3291 very useful. The developers have stopped working on ao-view to focus
3292 on a new, cross-platform ground station program. So ao-view may or
3293 may not be updated in the future. Mostly you just use
3294 the Log and Device menus. It has a wonderful display of the incoming
3295 flight data and I am sure you will enjoy what it has to say to you
3296 once you enable the voice output!
3300 <title>Drill Templates</title>
3302 These images, when printed, provide precise templates for the
3303 mounting holes in Altus Metrum flight computers
3306 <title>TeleMetrum template</title>
3308 TeleMetrum has overall dimensions of 1.000 x 2.750 inches, and the
3309 mounting holes are sized for use with 4-40 or M3 screws.
3311 <mediaobject id="TeleMetrumTemplate">
3313 <imagedata format="SVG" fileref="telemetrum.svg"/>
3318 <title>TeleMini template</title>
3320 TeleMini has overall dimensions of 0.500 x 1.500 inches, and the
3321 mounting holes are sized for use with 2-56 or M2 screws.
3323 <mediaobject id="TeleMiniTemplate">
3325 <imagedata format="SVG" fileref="telemini.svg"/>
3331 <title>Calibration</title>
3333 There are only two calibrations required for a TeleMetrum board, and
3334 only one for TeleDongle and TeleMini. All boards are shipped from
3335 the factory pre-calibrated, but the procedures are documented here
3336 in case they are ever needed. Re-calibration is not supported by
3337 AltosUI, you must connect to the board with a serial terminal program
3338 and interact directly with the on-board command interpreter to effect
3342 <title>Radio Frequency</title>
3344 The radio frequency is synthesized from a clock based on the 48 MHz
3345 crystal on the board. The actual frequency of this oscillator
3346 must be measured to generate a calibration constant. While our
3348 bandwidth is wide enough to allow boards to communicate even when
3349 their oscillators are not on exactly the same frequency, performance
3350 is best when they are closely matched.
3351 Radio frequency calibration requires a calibrated frequency counter.
3352 Fortunately, once set, the variation in frequency due to aging and
3353 temperature changes is small enough that re-calibration by customers
3354 should generally not be required.
3357 To calibrate the radio frequency, connect the UHF antenna port to a
3358 frequency counter, set the board to 434.550MHz, and use the 'C'
3359 command in the on-board command interpreter to generate a CW
3360 carrier. For TeleMetrum, this is best done over USB. For TeleMini,
3361 note that the only way to escape the 'C' command is via power cycle
3362 since the board will no longer be listening for commands once it
3363 starts generating a CW carrier.
3366 Wait for the transmitter temperature to stabilize and the frequency
3367 to settle down. Then, divide 434.550 MHz by the
3368 measured frequency and multiply by the current radio cal value show
3369 in the 'c s' command. For an unprogrammed board, the default value
3370 is 1186611. Take the resulting integer and program it using the 'c f'
3371 command. Testing with the 'C' command again should show a carrier
3372 within a few tens of Hertz of the intended frequency.
3373 As with all 'c' sub-commands, follow this with a 'c w' to write the
3374 change to the parameter block in the on-board DataFlash chip.
3377 Note that any time you re-do the radio frequency calibration, the
3378 radio frequency is reset to the default 434.550 Mhz. If you want
3379 to use another frequency, you will have to set that again after
3380 calibration is completed.
3384 <title>TeleMetrum Accelerometer</title>
3386 The TeleMetrum accelerometer we use has its own 5 volt power
3388 the output must be passed through a resistive voltage divider to match
3389 the input of our 3.3 volt ADC. This means that unlike the barometric
3390 sensor, the output of the acceleration sensor is not ratio-metric to
3391 the ADC converter, and calibration is required. Explicitly
3392 calibrating the accelerometers also allows us to load any device
3393 from a Freescale family that includes at least +/- 40g, 50g, 100g,
3394 and 200g parts. Using gravity,
3395 a simple 2-point calibration yields acceptable results capturing both
3396 the different sensitivities and ranges of the different accelerometer
3397 parts and any variation in power supply voltages or resistor values
3398 in the divider network.
3401 To calibrate the acceleration sensor, use the 'c a 0' command. You
3402 will be prompted to orient the board vertically with the UHF antenna
3403 up and press a key, then to orient the board vertically with the
3404 UHF antenna down and press a key. Note that the accuracy of this
3405 calibration depends primarily on how perfectly vertical and still
3406 the board is held during the cal process. As with all 'c'
3407 sub-commands, follow this with a 'c w' to write the
3408 change to the parameter block in the on-board DataFlash chip.
3411 The +1g and -1g calibration points are included in each telemetry
3412 frame and are part of the header stored in onboard flash to be
3413 downloaded after flight. We always store and return raw ADC
3414 samples for each sensor... so nothing is permanently "lost" or
3415 "damaged" if the calibration is poor.
3418 In the unlikely event an accel cal goes badly, it is possible
3419 that TeleMetrum may always come up in 'pad mode' and as such not be
3420 listening to either the USB or radio link. If that happens,
3421 there is a special hook in the firmware to force the board back
3422 in to 'idle mode' so you can re-do the cal. To use this hook, you
3423 just need to ground the SPI clock pin at power-on. This pin is
3424 available as pin 2 on the 8-pin companion connector, and pin 1 is
3425 ground. So either carefully install a fine-gauge wire jumper
3426 between the two pins closest to the index hole end of the 8-pin
3427 connector, or plug in the programming cable to the 8-pin connector
3428 and use a small screwdriver or similar to short the two pins closest
3429 to the index post on the 4-pin end of the programming cable, and
3430 power up the board. It should come up in 'idle mode' (two beeps),
3436 <title>Release Notes</title>
3438 <title>Version 1.3</title>
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3441 href="release-notes-1.3.xsl"
3442 xpointer="xpointer(/article/*)"/>
3445 <title>Version 1.2.1</title>
3447 xmlns:xi="http://www.w3.org/2001/XInclude"
3448 href="release-notes-1.2.1.xsl"
3449 xpointer="xpointer(/article/*)"/>
3452 <title>Version 1.2</title>
3454 xmlns:xi="http://www.w3.org/2001/XInclude"
3455 href="release-notes-1.2.xsl"
3456 xpointer="xpointer(/article/*)"/>
3459 <title>Version 1.1.1</title>
3461 xmlns:xi="http://www.w3.org/2001/XInclude"
3462 href="release-notes-1.1.1.xsl"
3463 xpointer="xpointer(/article/*)"/>
3466 <title>Version 1.1</title>
3468 xmlns:xi="http://www.w3.org/2001/XInclude"
3469 href="release-notes-1.1.xsl"
3470 xpointer="xpointer(/article/*)"/>
3473 <title>Version 1.0.1</title>
3475 xmlns:xi="http://www.w3.org/2001/XInclude"
3476 href="release-notes-1.0.1.xsl"
3477 xpointer="xpointer(/article/*)"/>
3480 <title>Version 0.9.2</title>
3482 xmlns:xi="http://www.w3.org/2001/XInclude"
3483 href="release-notes-0.9.2.xsl"
3484 xpointer="xpointer(/article/*)"/>
3487 <title>Version 0.9</title>
3489 xmlns:xi="http://www.w3.org/2001/XInclude"
3490 href="release-notes-0.9.xsl"
3491 xpointer="xpointer(/article/*)"/>
3494 <title>Version 0.8</title>
3496 xmlns:xi="http://www.w3.org/2001/XInclude"
3497 href="release-notes-0.8.xsl"
3498 xpointer="xpointer(/article/*)"/>
3501 <title>Version 0.7.1</title>
3503 xmlns:xi="http://www.w3.org/2001/XInclude"
3504 href="release-notes-0.7.1.xsl"
3505 xpointer="xpointer(/article/*)"/>
3510 <!-- LocalWords: Altusmetrum
projects / fw / altos / blob