A time interval measurement system based on FPGA used for frequency calibration

The performance of GPS based frequency standard depends on the accuracy and stability of the time interval measurement. Based on the XILINX Spartan-3 FPGA, this paper mainly describes a time interval measurement system which is controlled by the PicoBlaze soft core embedded processor and is suitable for the frequency calibration of GPS based frequency standard. Besides receiving the measurement data and the time information of GPS module, PicoBlaze is used to supervise the system status, which ensures the whole system work effectually. The system has been implemented using XC3S200 device and the test show that the whole system works perfectly and meets the requirement of GPS based frequency standard.