SYSID_ENFORCE: GCS sysid enforcement

Description

This controls whether packets from other than the expected GCS system ID will be accepted.

Values

• Default: 0

Description

This parameter adds a layer of security to the MAVLink communication link.

• Function: When enabled (1), the vehicle ignores all uplink commands (like mode changes or waypoint uploads) unless they come from a Ground Control Station whose System ID matches the value stored in SYSID_MYGCS.
• Usage: Useful if multiple pilots are flying in the same area on the same frequency/network to prevent cross-control.
• Warning: If you enable this and your GCS changes its System ID (or you use a different computer), you will be locked out of controlling the vehicle until you reset this parameter (e.g., via USB).

MAVLink GCS System ID (SYSID_MYGCS)

Description

SYSID_MYGCS sets the "Authorized" address for your ground control station (GCS).

In a MAVLink network, every device has a System ID. Most GCS software (Mission Planner, QGC) uses 255 as its default ID. This parameter tells the autopilot: "Only listen to commands from a GCS with this specific ID."

Tuning & Behavior

• Default: 255.
• Usage: For most users, leave at 255. Only change this if you are using a custom GCS or are operating in a multi-pilot environment where you want to lock your drone to a specific laptop/tablet to prevent accidental interference.
• Safety: If you change this value and your GCS ID doesn't match, you may lose the ability to send commands to the drone via telemetry.

Target vehicle's MAVLink system ID (SYSID_TARGET)

Description

This parameter tells the Antenna Tracker which MAVLink stream to listen to. In a swarm environment or at a flying field with multiple drones, this ensures your tracker points at your drone, not someone else's.

The Mathematics

MAVLink Message Filter:
$$ \text{Accept Packet} \iff (\text{Packet.SysID} == \text{SYSID\_TARGET}) \lor (\text{SYSID\_TARGET} == 0) $$

The Engineer's View

Defined in AntennaTracker/Parameters.cpp.

• 0 (Auto): The tracker will lock onto the first vehicle it receives a heartbeat from. Convenient for solo operations.
• 1-255: The tracker will strictly ignore all MAVLink traffic except that from the specified System ID.

Tuning & Behavior

• Default Value: 0
• Recommendation: Set to match your vehicle's SYSID_THISMAV (usually 1) to prevent accidental tracking of other aircraft.

MAVLink System ID (SYSID_THISMAV)

Description

SYSID_THISMAV sets the "Address" of your drone on the MAVLink network.

If you are flying multiple drones at the same time with the same Ground Control Station (GCS), each drone must have a unique SYSID_THISMAV. If two drones have the same ID, the GCS will get confused and may display erratic data or fail to send commands correctly.

• Default: 1.
• Recommended Range: 1 to 255.

Tuning & Behavior

• Default: 1.
• Action: Change this to any unique number (e.g., Drone 1 = 1, Drone 2 = 2) when performing multi-vehicle operations.
• Compatibility: Most MAVLink systems expect the GCS to be ID 255. Avoid setting your drone to 255.