Abstract:

This paper introduces a system for a new type of GPS/the Beidou locking second-class frequency standard of measuring time intervals based on the TDC-GP2 Chip. It also presents the overall design scheme for the system, develops the hardware and software frame, and implements the Kalman filter algorithm combined with the method of linear average for estimating and filtering noise. The universal TDC-GP2 produced by the ACAM company for measuring time interval of locked second-class frequency standard system is used by the satellite. By increasing another dividing frequency output signal 1PPS2, the measurement range is extended to -3.25～+3.25ms and the time resolution of 50ps is obtained. Experimental results show that the system's locked output frequency accuracy is as high as 10^-12(24-hour average). Frequency stability is better than 10^-11/s. Compared with the traditional frequency standard locked system, the system has the advantages of simple circuit, convenient adjustment, wide measurement range, small additional noise, and high precision.

Key words: frequency standard locked system, TDC-GP2 chip, global positioning system, Kalman filter