SATER modem used in microwave time transfer

The paper introduces the microwave time transfer system between timekeeping laboratory in Lintong and time & frequency control laboratory in Pucheng of National Time Service Center. The distance between timekeeping laboratory and time & frequency control laboratory is about 71 km. The microwave time transfer system was reconstructed in 2007, in order to transfer time signal more precisely, the digital channel was added to the system which adopted SATRE Modem to modulate and demodulate 1 pps signal. The time comparing data of the digital microwave time transfer system is measured by a counter, the data is sampled once an hour in about one month. Then the wrong data was processed by using some math methods before it is analyzed. By comparing the analyzed result of analog channel with digital channel, the conclusion was put forward at the end of the paper, including the reason that the microwave digital channel is more precise than analog channel and what cause its instability.