TWSTFT Network Status in the Pacific Rim Region and Development of a New Time Transfer Modem for TWSTFT

Abstract : Two-Way Satellite Time and Frequency Transfer "TWSTFT" is one of the most precise and accurate time transfer techniques. Recently TWSTFT results among the European and North American time and frequency institutes have been started applying to the TAI calculation. A TWSTFT network in the Pacific Rim region is also being developed rapidly. CRL and NRLM in Japan, NML in Australia, CSAO in China, and TL in Taiwan have been doing TWSTFT time transfer on a regular basis. Some other institutes, such as KRlSS in South Korea and PSB in Singapore, are also planning to join this network within 1 year. By performing TWSTFT time transfer it became obvious that several problems in TWSTFT should be solved for practical use and contribution to TAI with the full performance of TWSTFT. We have been developing a new time transfer modem to solve or reduce most of these problems with TWSTFT. It has three PRN code modulator units for transmission and eight PRN code demodulator and time-interval measurement units for receiving. It realizes simultaneous time transfer among up to eight stations.