- <section>
- <title>Packet Command Mode</title>
- <subtitle>Controlling An Altimeter Over The Radio Link</subtitle>
- <para>
- One of the unique features of the Altus Metrum environment is
- the ability to create a two way command link between TeleDongle
- and an altimeter using the digital radio transceivers built into
- each device. This allows you to interact with the altimeter from
- afar, as if it were directly connected to the computer.
- </para>
- <para>
- Any operation which can be performed with TeleMetrum can
- either be done with TeleMetrum directly connected to the
- computer via the USB cable, or through the packet
- link. TeleMini doesn't provide a USB connector and so it can
- only be controlled through the packet link. Select the
- appropriate TeleDongle device when the list of devices is
- presented and AltosUI will use packet command mode.
- </para>
- <para>
- One oddity in the current interface is how AltosUI selects the
- frequency for packet mode communications. Instead of providing
- an interface to specifically configure the frequency, it uses
- whatever frequency was most recently selected for the target
- TeleDongle device in Monitor Flight mode. If you haven't ever
- used that mode with the TeleDongle in question, select the
- Monitor Flight button from the top level UI, pick the
- appropriate TeleDongle device. Once the flight monitoring
- window is open, select the desired frequency and then close it
- down again. All Packet Command Mode operations will now use
- that frequency.
- </para>
- <itemizedlist>
- <listitem>
- <para>
- Save Flight Data—Recover flight data from the rocket without
- opening it up.
- </para>
- </listitem>
- <listitem>
- <para>
- Configure altimeter apogee delays or main deploy heights
- to respond to changing launch conditions. You can also
- 'reboot' the altimeter. Use this to remotely enable the
- flight computer by turning TeleMetrum on in "idle" mode,
- then once the air-frame is oriented for launch, you can
- reboot the altimeter and have it restart in pad mode
- without having to climb the scary ladder.
- </para>
- </listitem>
- <listitem>
- <para>
- Fire Igniters—Test your deployment charges without snaking
- wires out through holes in the air-frame. Simply assembly the
- rocket as if for flight with the apogee and main charges
- loaded, then remotely command the altimeter to fire the
- igniters.
- </para>
- </listitem>
- </itemizedlist>
- <para>
- Packet command mode uses the same RF frequencies as telemetry
- mode. Configure the desired TeleDongle frequency using the
- flight monitor window frequency selector and then close that
- window before performing the desired operation.
- </para>
- <para>
- TeleMetrum only enables packet command mode in 'idle' mode, so
- make sure you have TeleMetrum lying horizontally when you turn
- it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
- flight and will not be listening for command packets from TeleDongle.
- </para>
- <para>
- TeleMini listens for a command packet for five seconds after
- first being turned on, if it doesn't hear anything, it enters
- 'pad' mode, ready for flight and will no longer listen for
- command packets. The easiest way to connect to TeleMini is to
- initiate the command and select the TeleDongle device. At this
- point, the TeleDongle will be attempting to communicate with
- the TeleMini. Now turn TeleMini on, and it should immediately
- start communicating with the TeleDongle and the desired
- operation can be performed.
- </para>
- <para>
- When packet command mode is enabled, you can monitor the link
- by watching the lights on the
- devices. The red LED will flash each time they
- transmit a packet while the green LED will light up
- on TeleDongle while it is waiting to receive a packet from
- the altimeter.
- </para>
- </section>