+ <section>
+ <title>Controlling An Altimeter Over The Radio Link</title>
+ <para>
+ One of the unique features of the Altus Metrum system 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 radio
+ link. TeleMini doesn't provide a USB connector and so it is
+ always controlled through the radio link. Select the
+ appropriate TeleDongle device when the list of devices is
+ presented and AltosUI will interact with an altimter over the
+ radio link.
+ </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>