Research And Implementation Of BeiDou B1C Signal Acquisition Algorithm

The Bei Dou Navigation Satellite System(BDS)has completed the global networking.To further improve the Navigation and positioning performance,a new Bei Dou B1 C signal has been added at the frequency of B1.The signal adopts the multiplexing BOC modulation method,achieving compatibility and interoperability with other Satellite Navigation systems.In the design of B1 C signal,due to the introduction of new technologies such as layered code structure,multiplexed modulation and data,pilot dual-channel,etc.,it is more difficult to reproduce local signal than BPSK modulation signal,and the baseband data processing will also increase.For navigation receivers,signal acquisition is an important prerequisite for baseband signal processing and positioning.In order to achieve the same acquisition performance as BPSK signal under limited hardware resources,it is of great significance to study and implement the B1 C signal acquisition algorithm.The main research work of this paper is as follows:Aiming at the hardware resource optimization problem of B1 C signal acquisition,an improved joint acquisition algorithm based on PMF-FFT based on average median Filter was proposed considering the acquisition sensitivity,acquisition time and algorithm complexity.Simulation results show that the proposed algorithm is effective.Secondly,FPGA hardware circuit design for local B1 C signal generation,including clock driver,code generator,code controller,carrier and subcarrier generator and other basic modules.Considering the complexity of B1 C code sequence,the circuit of code generator based on dual-port memory is designed.The structure of circuit not only realizes the parallel output of multipath code,but also saves a lot of hardware resources.In addition,in order to realize the design of B1 C signal acquisition algorithm,hardware circuits such as mixer,integral accumulator,piece-matching filter and FFT are designed by Verilog HDL.Thirdly,aiming at the design of B1 C signal acquisition,a B1 C signal receiving configuration scheme based on MAX2771 RF front end is designed.On this basis,the overall framework of acquisition was designed based on Zynq-7000.In order to realize the control and threshold of acquisition,the communication circuit of FPGA-ARM is designed,and the delay time from capture to trace is reduced.Finally,for evaluating the performance of subjects to acquisition scheme,designed the B1 C signal data collection,internal communication of chip,basic modules of logic and algorithm testing of B1 C acquisition,focusing on the acquisition of signal,time of acquisition,the sensitivity of acquisition and resource consumption content,the results prove that the scheme of acquisition satisfies the requirements of design,saves a lot of hardware resources,shows high practical value.