Utilizing both UARTs on an AVR ATtiny841, I've interfaced a Kenwood TK-780 mobile radio, a Garmin x18 OEM GPS module and a laptop. The system will automatically key-up the VHF radio and capture the received signal strength from the repeater and tag it with the current GPS position. All of the output is piped to the laptop as an ASCII CSV string.
The data is compiled and used to produce relative signal strength maps to help define repeater coverage areas.
nbytes from GPS, fix valid/invalid, lat, long, RSSI in mV