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Two-way satellite time and frequency transfer(TWSTFT) has been recognized as one of the most accurate means for remote clock comparisons. The advantage is that the symmetry of the signal paths of two earth stations makes the errors to be mostly canceled. In two-way links, it is found that there are diurnal variety error whose magnitude is 1–3ns in most TWSTFT results. Combined with the character of...
For the TAI (International Atomic Time) Calculation of two-way satellite time and frequency transfer (TWSTFT) is based on a geostationary orbit satellite and KU band time transfer. Effect of time transfer precision of many factors: the modem time delay, the uplink and downlink path delay, the time delay of satellite transponder and Sagnac time delay etc. Limited by domestic satellite resource, we...
Modem is the important equipment in two way satellite time and frequency transfer (TWSTFT, short for TW). It takes the role of modulating and demodulating the one pulse per second (1PPS). With the using of the multi-channel technology in TWSTFT, multi-channel modem is carried on. The multi-channel modem concerned in this paper is NICT modem while the single channel modem is the TWT-100. In this paper,...
We report first results obtained with the Two Way Satellite Time and Frequency Transfer (TWSTFT) between LNE-SYRTE and NTSC using the IS-4 commercial geostationary satellite at 72degE operating in Ku band. This work is part of the activities recommended by the CCTF working group on TWSTFT. The detailed study of the measurement uncertainty is presented, with particular attention to the fluctuation...
Impact of satellite motion on the Asia-Pacific TWSTFT links are analyzed and calculated. Based on the satellite motion, three aspects, which are the different distances from two stations to the satellite, time synchronization error in stations, and the Sagnac effect, result in the non-reciprocal path affecting the TWSTFT accuracy
Based on several two-way satellite time and frequency transfer (TWSTFT) links and multichannel time transfer modems, a positioning method to geostationary communication satellite is presented, moreover, the accuracy of the positioning is concisely estimated. The characteristics of the method are simple and practical. Especially, the positioning system is completely established on TWSTFT links, so...
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