Editing SimTX API/Tracking and pointing (section)

== Tracking ==
[[SimTX API/Data types#Tracking|Tracking]] says what a session follows:

<syntaxhighlight lang="protobuf">
message Tracking {
  bytes target_station_id = 1;
  bool point_antenna = 2;     // drive the antenna's rotator toward the target
  bool doppler_correct = 3;   // RX: shift tuning by the target's Doppler; TX: pre-correct so it arrives on frequency
  // Simulation time at which the rotator began slewing toward this target (point_antenna only; both 0 =
  // not known). Servers set it in SessionStatus; with the antenna's slew rate it gives the rotator position.
  // Ignored in a client's start or AntennaPointingUpdate.
  int64 since_epoch_seconds = 4;
  int32 since_nanos = 5;
}
</syntaxhighlight>

* <code>target_station_id</code>: the station to follow, usually a satellite from the satellite catalog.
* <code>point_antenna</code>: drive the antenna's rotator towards the target. Needs an <code>AZ</code> or <code>AZEL</code> mount.
* <code>doppler_correct</code>: correct the session's frequency for the target's Doppler shift.

Set <code>tracking</code> in [[SimTX API/Packets/ReceiverStart|ReceiverStart]] or [[SimTX API/Packets/TransmitterStart|TransmitterStart]] to follow a target from the start.