This is a long range telemetry modem which uses the audio channel of your on board video transmitter to transmit data. This is delivered to you as a simple kit which you can solder together. If you pair this with another modem connected to your laptop/computer via a serial FTDI interface you can read back data from your AeroQuad such as GPS coordinates and battery capacity.
This has been used at the UAVForge competition to allow us to transmit telemetry over a range of 2+ miles. The AeroQuad flight software also uses a data error correction algorithm to ensure the integrity of your data being received over great distances. This modem is only limited by the range of your video transmitter. Both the modem design and the implementation of the error correction algorithm is done by Kha, our community member and AeroQuad software team member!
Build information and additional tech info found here