Hi Alex,
Thanks for clarifying the direction. For UAS → GCS with your current voxl-vtx 1.7.1:
- Autopilot telemetry already goes VTX → VRX → Ethernet UDP:
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voxl-vtx subscribes to the autopilot's MAVLink stream from voxl-mavlink-server and sends it over the RF link next to the video. The VRX then re-sends it as UDP to:
- destination: gcs_ip in /etc/modalai/voxl-vrx.conf (default 10.0.0.1), port 14550 (fixed in 1.7.1)
- source: the VRX at 10.0.0.2
- Give your GCS laptop 10.0.0.1 on the VRX Ethernet link (or set gcs_ip to its address) and listen on UDP 14550. QGC will pick it up automatically.
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This is a one-way telemetry snapshot, not a transparent MAVLink link. The VTX sends at mavlink_telem_rate_hz (30 Hz in your config) and keeps one message of each message ID per send window.
- Custom companion data: not supported in this release.
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voxl-vtx only forwards what voxl-mavlink-server publishes on its mavlink_onboard pipe, and that pipe only carries messages received from the autopilot. If a companion app writes MAVLink into that pipe, voxl-mavlink-server sends it to the autopilot and doesn't publish it back onto the pipe, so voxl-vtx never sees it.
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Writing to the mavlink_to_gcs pipe doesn't help either: voxl-mavlink-server sends those messages out its own UDP sockets, and they have no way to reach the ground over the MVX link. There is currently no supported way to put your observation data onto the VTX → VRX link.
- Upgrading to SDK 1.6.4, if these features are useful to you:
Your voxl-vtx 1.7.1 is older than what ships in SDK 1.6.4, the latest SDK release for Stinger. SDK 1.6.4 includes voxl-vtx 2.2.x, which adds:
- Parameter, mission and FTP forwarding to the GCS, so QGC can read and set parameters and download missions over the MVX link.
- GCS → drone MAVLink through the VRX. MAVLink your GCS sends to the VRX on the GCS port is forwarded over the link to the aircraft, for example mission uploads. By default this forwarding stops while the vehicle is armed. To keep GCS → drone MAVLink flowing in flight, set this in /etc/modalai/voxl-vrx.conf and restart voxl-vrx:
"allow_mavlink_forward_while_armed": true- Only enable this if you want the GCS able to send commands to the aircraft while it is armed. MANUAL_CONTROL messages are dropped.
- A configurable GCS port (mavlink_gcs_port), replacing the fixed 14550.
- None of these add a path for custom companion data, so they don't solve the observation use case.
- WiFi client mode with the VTX active:
On the Stinger the M0185 is the VTX radio, and it runs in raw injection/monitor mode while it sends video. It can't also join a network as a WiFi client. A TCP/IP WiFi link would need a second, separate WiFi adapter. Even then, running it on the same band as the video link could hurt video quality, so we'd advise against it for a flight setup unless you deconflict the frequency used by each network device.
