Telemetry via FPV Audio Channel rather than 915 radios?

Is there an easy and open-source way to take an aircraft’s telemetry (primarily GPS), inject it into the audio channel of an FPV transmitter, and decode it on the ground to drive an ardutracker?

I would like to eliminate the separate weight, interference and power requirements of my current 915 telemetry radios, and my Vtx is higher-powered too. I’m using Ardupilot, but the Ardutracker solution assumes you’re working separate telemetry radios. I know there are some commercial solutions that do this (e.g. EZOsd), but they’re very pricey.

I rate myself a noob at radio and programming, somewhat better at soldering.

Yes. It is entirely possible.
You can use a FSK modem IC. A couple of simpler ones are the TCM3105 and the MX614.
They both convert serial data to from FSK and work very well. The TCM3105 requires more adjustment with pots etc though to get it working

(It is also possible to use a microcontroller with a DAC to send FSK, and to receive using an ADC, but the chips above work well.

As for a protocol, this is the one I used

Thank you! Although I note that, given my lack of hardware and software expertise, this summarizes my level of comprehension of what to do next :wink: :slight_smile:

There is a project here that uses the TCM3105

You can view the board by installing the Freebie Eagle ECAD app

It has been used by Ghettostation antennatracker
More info here

I have a simple question, so I did not create a separate topic.
I want to collect a managed model controlled by mobile communication.
An analog of a military drone.
Is there such functionality for the controllers, if so which ones?
I did not understand this for a long time, so I could skip something.
I really hope for understanding.
Thanks to all.