The positioning method of BDS receiver with auxiliary clock under the weak signal circumstance

摘要

The traditional time-of-transmission recovery algorithm cannot be applied to practice due to a drastic calculation increase when the approximate position of receiver is unknown. This paper puts forward a receiver positioning method based on auxiliary clock, which can be used when the receiver’s approximate position is unknown. To determine search scope, the paper makes use of double GEO satellites to build custom polar coordinates, and reduces unknown searching numbers on the basis of elevation range information implied in the receiver. Furthermore, according to the restraints of satellite signal coverage scope, it is advocated to choose two farthest GEO satellites to build the custom coordinate system, and add any validation satellites for verification and selection, so as to realize the restoration of millisecond integer of signal transmission time. This method is verified through simulation analysis. To be specific, statistical analysis of the algorithm’s precision requirements of auxiliary clock is made under the application circumstance of only GEO constellation in China and neighbouring areas. The conclusion shows that, when the auxiliary clock error is below 100 us and the number of validation satellites is enough, the receiver can be rapidly positioned under the weak signal circumstance even when the approximate position is unknown.