Time Comparison Experiments with Small K-Band Antennas and SSRA Equipments via a Domestic Geostationary Satellite

Time comparison experiments were made for the development of a domestic accurate time-comparison system via the K-band (30/20-GHz) link of a Japanese geostationary satellite (CS). In the experiments, SSRA communication equipment and K-band earth stations such as a 13-m antenna main station, a 2-m antenna headquarters station, and a 1-m antenna automobile station were used. Time fluctuation of about 1 ns (rms) and frequency stability of less than 1 X 10-13 (for averaging time of 100-200 min) were achieved in the two-way time transfer method. The accuracies of the experiments were estimated as about 13 ns for the time comparison between the main station and the headquarters one, referred to a two-way time transfer through a ground microwave link, and about 0.74 ns for that between the two small (mobile) stations by method of a two-way time transfer experiment at a single site with a common clock. We measured the station time delays by insertion of a pulse-modulated signal and its detection at each of the up-link path and the down-link path of the station, and obtained the results with accuracies of 3.6 ns for the mobile stations and 7.7 ns for the main station.