Patent ID: 8384590

Claim:
A system comprising a plurality of devices for time synchronization, wherein each device comprises: a global positioning system (GPS) receiver for receiving GPS signals to determine location and generate positioning information and a pulse per second (PPS) signal; an oscillator for generating a periodic signal; a microprocessor coupled to the GPS receiver and the oscillator for receiving the PPS signal and the periodic signal, the microprocessor comprising a timer for generating a clock signal according to the periodic signal; wherein the microprocessor generates a drift per second according to the difference between the PPS signal and the clock signal; and a wireless transceiver coupled to the microprocessor for transmitting the positioning information to the other devices and receiving positioning informations from the other devices; wherein the microprocessor turns off the GPS receiver and calibrates the clock signal constantly according to the drift per second, and then the GPS receiver is turned on after a pre-determined time period to update the drift per second and calibrate the clock signal with the updated drift per second, thereby forming cycle.