Connecting 3DR radio telemetry to rpi

I want to make a follower drone, which will follow a target drone. for this I’m using a radio telemetry. the air module will be placed on the target drone and the ground module will be placed on the follower drone. On the follower drone the ground module will be connected to a raspi which will encode the GPS data of target drone and send it to the follower drone’s FC.
Here I’m unable to read that the data from the telemetry on the follower drone on rpi can anyone please help me with this.