or radio link via TeleDongle.
</para>
<section>
- <title>Radio Frequencies</title>
+ <title>Radio Frequency</title>
<para>
Altus Metrum boards support radio frequencies in the 70cm
band. By default, the configuration interface provides a
altimeter and TeleDongle must be configured to the same
frequency to successfully communicate with each other.
</para>
- <para>
- To set the radio frequency, use the 'c R' command to specify the
- radio transceiver configuration parameter. This parameter is computed
- using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
- the standard calibration reference frequency, 'S', (normally 434.550MHz):
- <programlisting>
- R = F / S * C
- </programlisting>
- Round the result to the nearest integer value.
- As with all 'c' sub-commands, follow this with a 'c w' to write the
- change to the parameter block in the on-board flash on
- your altimeter board if you want the change to stay in place across reboots.
- </para>
</section>
<section>
<title>Apogee Delay</title>
primary and backup pyrotechnic charges do not fire simultaneously.
</para>
<para>
- To set the apogee delay, use the 'c d' command.
- As with all 'c' sub-commands, follow this with a 'c w' to write the
- change to the parameter block in the on-board DataFlash chip.
- </para>
- <para>
- Please note that the Altus Metrum apogee detection algorithm
- fires exactly at apogee. If you are also flying an
- altimeter like the PerfectFlite MAWD, which only supports
- selecting 0 or 1 seconds of apogee delay, you may wish to
- set the MAWD to 0 seconds delay and set the TeleMetrum to
- fire your backup 2 or 3 seconds later to avoid any chance of
- both charges firing simultaneously. We've flown several
- air-frames this way quite happily, including Keith's
- successful L3 cert.
+ The Altus Metrum apogee detection algorithm fires exactly at
+ apogee. If you are also flying an altimeter like the
+ PerfectFlite MAWD, which only supports selecting 0 or 1
+ seconds of apogee delay, you may wish to set the MAWD to 0
+ seconds delay and set the TeleMetrum to fire your backup 2
+ or 3 seconds later to avoid any chance of both charges
+ firing simultaneously. We've flown several air-frames this
+ way quite happily, including Keith's successful L3 cert.
</para>
</section>
<section>
than the primary so that both pyrotechnic charges don't fire
simultaneously.
</para>
- <para>
- To set the main deployment altitude, use the 'c m' command.
- As with all 'c' sub-commands, follow this with a 'c w' to write the
- change to the parameter block in the on-board DataFlash chip.
- </para>
+ </section>
+ <section>
+ <title>Maximum Flight Log</title>
+ <para>
+ TeleMetrum version 1.1 has 2MB of on-board flash storage,
+ enough to hold over 40 minutes of data at full data rate
+ (100 samples/second). TeleMetrum 1.0 has 1MB of on-board
+ storage. As data are stored at a reduced rate during
+ descent, there's plenty of space to store many flights worth
+ of data.
+ </para>
+ <para>
+ The on-board flash is partitioned into separate flight logs,
+ each of a fixed maximum size. Increase the maximum size of
+ each log and you reduce the number of flights that can be
+ stored. Decrease the size and TeleMetrum can store more
+ flights.
+ </para>
+ <para>
+ All of the configuration data is also stored in the flash
+ memory, which consumes 64kB on TeleMetrum v1.1 and 256B on
+ TeleMetrum v1.0. This configuration space is not available
+ for storing flight log data.
+ </para>
+ <para>
+ To compute the amount of space needed for a single flight,
+ you can multiply the expected ascent time (in seconds) by
+ 800, multiply the expected descent time (in seconds) by 80
+ and add the two together. That will slightly under-estimate
+ the storage (in bytes) needed for the flight. For instance,
+ a flight spending 20 seconds in ascent and 150 seconds in
+ descent will take about (20 * 800) + (150 * 80) = 28000
+ bytes of storage. You could store dozens of these flights in
+ the on-board flash.
+ </para>
+ <para>
+ The default size, 192kB, allows for 10 flights of storage on
+ TeleMetrum v1.1 and 5 flights on TeleMetrum v1.0. This
+ ensures that you won't need to erase the memory before
+ flying each time while still allowing more than sufficient
+ storage for each flight.
+ </para>
+ </section>
+ <section>
+ <title>Ignite Mode</title>
+ <para>
+ Instead of firing one charge at apogee and another charge at
+ a fixed height above the ground, you can configure the
+ altimeter to fire both at apogee or both during
+ descent. This was added to support an airframe that has two
+ TeleMetrum computers, one in the fin can and one in the
+ nose.
+ </para>
+ <para>
+ Providing the ability to use both igniters for apogee or
+ main allows some level of redundancy without needing two
+ flight computers. In Redundant Apogee or Redundant Main
+ mode, the two charges will be fired two seconds apart.
+ </para>
+ </section>
+ <section>
+ <title>Pad Orientation</title>
+ <para>
+ TeleMetrum measures acceleration along the axis of the
+ board. Which way the board is oriented affects the sign of
+ the acceleration value. Instead of trying to guess which way
+ the board is mounted in the air frame, TeleMetrum must be
+ explicitly configured for either Antenna Up or Antenna
+ Down. The default, Antenna Up, expects the end of the
+ TeleMetrum board connected to the 70cm antenna to be nearest
+ the nose of the rocket, with the end containing the screw
+ terminals nearest the tail.
+ </para>
</section>
</section>
<section>
temperature changes is small enough that re-calibration by customers
should generally not be required.
</para>
- <para>
- To calibrate the radio frequency, connect the UHF antenna port to a
- frequency counter, set the board to 434.550MHz, and use the 'C'
- command to generate a CW carrier. Wait for the transmitter temperature
- to stabilize and the frequency to settle down.
- Then, divide 434.550 MHz by the
- measured frequency and multiply by the current radio cal value show
- in the 'c s' command. For an unprogrammed board, the default value
- is 1186611. Take the resulting integer and program it using the 'c f'
- command. Testing with the 'C' command again should show a carrier
- within a few tens of Hertz of the intended frequency.
- As with all 'c' sub-commands, follow this with a 'c w' to write the
- change to the parameter block in the on-board DataFlash chip.
- </para>
<para>
- when the radio calibration value is changed, the radio
+ When the radio calibration value is changed, the radio
frequency value is reset to the same value, so you'll need
to recompute and reset the radio frequency value using the
new radio calibration value.
Verify you can connect and disconnect from the units while in your
terminal program by sending the escape-disconnect mentioned above.
</para>
+ <para>
+ To set the radio frequency, use the 'c R' command to specify the
+ radio transceiver configuration parameter. This parameter is computed
+ using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
+ the standard calibration reference frequency, 'S', (normally 434.550MHz):
+ <programlisting>
+ R = F / S * C
+ </programlisting>
+ Round the result to the nearest integer value.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board flash on
+ your altimeter board if you want the change to stay in place across reboots.
+ </para>
+ <para>
+ To set the apogee delay, use the 'c d' command.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board DataFlash chip.
+ </para>
+ <para>
+ To set the main deployment altitude, use the 'c m' command.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board DataFlash chip.
+ </para>
+ <para>
+ To calibrate the radio frequency, connect the UHF antenna port to a
+ frequency counter, set the board to 434.550MHz, and use the 'C'
+ command to generate a CW carrier. Wait for the transmitter temperature
+ to stabilize and the frequency to settle down.
+ Then, divide 434.550 MHz by the
+ measured frequency and multiply by the current radio cal value show
+ in the 'c s' command. For an unprogrammed board, the default value
+ is 1186611. Take the resulting integer and program it using the 'c f'
+ command. Testing with the 'C' command again should show a carrier
+ within a few tens of Hertz of the intended frequency.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board DataFlash chip.
+ </para>
<para>
Note that the 'reboot' command, which is very useful on the altimeters,
will likely just cause problems with the dongle. The *correct* way
strength providing an indication of the direction from receiver to rocket.
</para>
<para>
- TeleMetrum also provides GPS trekking data, which can further simplify
+ TeleMetrum also provides GPS tracking data, which can further simplify
locating the rocket once it has landed. (The last good GPS data
received before touch-down will be on the data screen of 'ao-view'.)
</para>
projects / fw / altos / blobdiff