Telemetry Overlay

Hello, I have a question, is it possible to add a com port with a serial string that displays an external tether length counter in the telemetry overlay? similar way as the telemtry video overlays shows the depth ?
i know i can add the data as subtitles in VLC after but its a lot of work to implement tether length after hours of video.

Hi @Zirhc, welcome to the forum :slight_smile:

QGroundControl has a built in set of MAVLink messages that it accepts and can display for the telemetry values. It’s possible to build a custom version of QGroundControl to accept an additional message type[1], but given you’re only wanting a distance measurement you should be able to re-use one of the distance measurement types it already accepts by sending DISTANCE_SENSOR messages.

  1. Example here ↩︎


thanks, but the sensor is connected directly to the topside computer is this solution still possible then?

I believe that should be possible by either

  1. Sending your messages via the loopback IP (, or
  2. Sending your messages to the autopilot, which it will then relay to QGC

do i need to program the messages into mavlink and then send them or how do i send them through the loopback ip

Yes, you would need a program that does roughly

def setup():
    ... # connect to and initialise serial device
    ... # make UDP MAVLink connection to desired IP address and port

def loop():
    ... # read tether length from serial device
    ... # send it as a MAVLink message

I would personally approach that using Python, with the pymavlink and pyserial libraries, but it should be possible in most programming languages if you have some other preference.