A self-powered positioning and modem system, which is adapted for linking to a radio frequency transmitter of a communication device to communicating with a communication system through radio frequency signals, includes a GPS controller for communicatively linking to the radio frequency transmitter. The GPS controller includes a position information receptor receiving a positioning data, a signal converter linked to the position information receptor to encode the positioning data into a RF positioning signal in form of audio signal, wherein the GPS controller is triggered for wirelessly transmitting the RF positioning signal through the radio frequency transmitter to the communication system.