【摘 要】
：
The efficiency of Search and Rescue(SAR)heavily relies on the positioning accuracy,so high positioning accuracy is very important in the proce-dure of SAR,especially when searched and rescued object (
【机 构】
：
National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China; Department of Civil
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The efficiency of Search and Rescue(SAR)heavily relies on the positioning accuracy,so high positioning accuracy is very important in the proce-dure of SAR,especially when searched and rescued object (SARO) dropped into the place where the number of the visible satellites is very small.It is necessary to know the position of the SARO by using as less satellites as possible because of the signal sheltered.Combining with the principle of time-and-frequency-difference of arrival (TDOA and FDOA,respectively) and differential technology of positioning error correction in Global Positioning System (GPS),pseudo-range differential positioning method basing on TDOA and FDOA is put forward in the procedure of SAR with two satellites.By choosing the proper reference object (RO),the pseudo-range correction of RO is used to correct pseudo-range of the SARO so that more accurate position of SARO is solved.Finally,simulation results show that the positioning accuracy can be improved and can precede 5km after differential by selecting RO and SARO which are within 1000km apart for pseudo-range differential technology.
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