FreeTrack 2.02 - GPS to APRS Tracking Encoder [1]

"This encoder will turn serial NMEA data from a GPS receiver into APRS format AX.25 data packets.
By using this hardware with a 2 meter ham radio and the freely available APRS computer software, you can track the location of the GPS on a map in real time. Latest release now supports the mic-e compressed data format for much smaller packets.

The unique aspect of the design is in how it creates frequency shift keying (FSK) tones with the PICs built in 4 bit voltage reference instead of a modem chip.
FreeTrak's built in configuration routines allow you to enter all it's parameters with any serial terminal program."