Research On The Key Techniques Of Assisted BeiDou Position

With the increasing demand for location-based services and the requirements for firsttime positioning and positioning accuracy,especially for weak signals,Assisted Global Navigation Satellite System(A-GNSS)assisted positioning technology has become the field of navigation.Research hotspots;the key technology of Assisted BeiDou(A-BD)has also set off an upsurge of research in China.A-BD is a new positioning technology based on China's self-developed and self-developed Beidou navigation satellite system.The wireless communication network is combined to obtain important auxiliary information,and auxiliary information is used to reduce positioning time and improve accuracy.This paper conducts indepth research on the key techniques of Beidou-assisted positioning:In order to capture the Beidou-assisted positioning algorithm,the parallel code phase acquisition algorithm is improved,and the auxiliary information is used to reduce the number of search times captured.After the zero complement of the BD satellite signal,the effect of the NH code can be solved after the fast Fourier transform.The capture algorithm can achieve the capture of BeiDou signal;for the shortcomings of the improved capture algorithm,a joint capture strategy is proposed.The joint capture first uses the parallel code phase to perform coarse capture frequency estimation,and the serial frequency of rough capture frequency Fine capture,this strategy can improve the capture performance.In the weak signal,the conventional bit synchronization can't achieve synchronization basically.A slope synchronization method is proposed to perform energy accumulation for the BeiDou signal for a long time,curve fitting is performed for the energy accumulation point,and the candidate position is maximally calculated.At the slope point,the algorithm is computationally large,but it can achieve bit synchronization under weak signals.The experimental simulation shows that the slope synchronization accuracy is better than the histogram and KP method.When the receiver can only receive 1 to 2 satellite signals,the receiver can capture the Doppler observations of other satellites but cannot obtain the complete pseudorange.The Beidou-assisted positioning based on Doppler measurements combined with pseudoranges is proposed.The algorithm,through experimental simulation and analysis,shows that the positioning algorithm can achieve positioning only when the weak signal can only receive 1 to 2 satellite signals.The positioning accuracy error of two signals is in the range of ten meters.