I am planning to control my tracked robot via an xbee link and I would to use directional antennas to get the maximum possible range. So I would like to interface this gps based antenna tracker with an arduino to consistently keep the antennas pointed at my bot. I understand this tracker uses http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_21&products_id=54
Typically the gps information is send through the audio channel on an fpv transmitter. I remember after some googling I was able to find out how it was done. Now I can't seem to find it anywhere. Does anyone know what this type of communication is called and have any suggestions on how to convert my gps data to something the tracker can understand?