A new method of Common-view time transfer with transfer mode(TCV for abbreviation) via GEO telecommunication satellite is put forward, with which we can transfer the standard time kept in a time keeping laboratory, such as UTC (NTSC), to many users in the local area covered by the GEO satellite's signal. The time keeping laboratory is equipped with transmitting device and receiving device, and their external reference is from the main clock of the lab. The pseudo-code ranging signal is generated by the transmitting device in the lab, and is transmitted to the GEO satellite via a paraboloidal antenna, and then is broadcasted to the earth by the satellite. The pseudo-range from transmitter to GEO satellite and to the receiving device is measured in the lab. And at the same time the pseudo-range from transmitter to GEO satellite and to the user time receiver is also measured. By processing the pseudo-range measured by the user time receiver and that measured in the lab with paraboloidal antenna in common-view method, we can get the time difference between the user receiver clock and the main clock in the lab, carrying out the common-view time transfer with transfer mode (TCV). The precise coordinates of paraboloidal antenna in NTSC and the user time receiver, as well as precise orbit of the GEO satellite should be known in advance in this method. Chinese national standard time, UTC (NTSC) is kept in National Time Service Center (NTSC), Chinese Academy of Science. Based on the device of Two-Way Satellite Time and Frequency Transfer with C-band (TW(C) for abbreviation) in NTSC and Xinjiang Astronomical Observatory (XAO), we did TCV experiment. Both the transmitting and receiving units of the TW(C) device in NTSC are used, and only the receiving unit of the TW(C) device in XAO is used as a user time receiver. The main clock of UTC (NTSC) is a HP5071A Cs atomic clock, and an OSA5585 PRS Cs atomic clock is equipped in XAO. SATRE MODEM made by Timetech Company in Germany i- used in our TW(C) devices and the code rate is 20MChips. The GEO satellite used in the experiment is Sinosat-1 telecommunication satellite (110.5°E). For the data processing in TCV method, the precise coordinates of the transmitting station and the receiving station are known in advance, the satellite orbit is provided by the Chinese Area Positioning System (CAPS) of Chinese Academy of Sciences, orbit precision is on the level of meter. And the system errors including Sagnac effect, ionosphere delay, troposphere delay etc, are taken out during the data processing, but the device delay is not deducted. We compare the results of TCV and TW(C), and it shows that ignoring the device delay (almost constant), the RMS of the difference between TCV and TW(C) is about 1ns for five consecutive days, and such result is very better than that in GPS Common-view time transfer with code.
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