Time synchronization design based on FPGA in integrated GPS/INS system

A new solution for time synchronization using GPS receiver signals as reference is proposed. In the GPS/INS applications, unknown time errors between IMU (Inertial Measurement Unit) measurements and GPS time have a significant influence on the data fusion performance of hybrid filter. However, each of exiting methods for time synchronization bears such-and-such shortcomings, for example high cost, complex or just dedicated to special situation etc. In order to improve the accuracy of time synchronization, we utilize 1PPS (Pulse Per Second) signal from GPS receiver as a synchronization reference, and tag time stamp on the serial data package from IMU. This scheme is implemented with a Field Programmable Gate Array (FPGA) device in Verilog programming language. Results of simulation and experiment show that with a simpler hardware design compared to exiting methods, the proposed solution of time synchronizer can reach the time synchronization accuracy on 1 millisecond level.