Research And Implementation Of Baseband Signal Processing Technologies In Real-Time Wide-Band Navigation Receivers

The application of Global Navigation Satellite System(GNSS)becomes gradually complete and widespread.However,the vulnerability of GNSS signal itself makes it easily suffer from interference,which causes the decline in positioning accuracy and even the failure of positioning,therefore the wide-band GNSS software receivers which can monitor interference gradually grow up to new research hotspots.Most of existing real-time software receivers are designed for ordinary civilian demand.For those receivers,the bandwidth of RF front-end is too low,the quantization bits is too small and the speed of base-band signal processing is too low,which means they can't process the signals of wide-band receivers real-timely.In order to achieve the real-time processing of GNSS signals which features wide bandwidth,high sampling rate and high quantization bits,this thesis studies the techniques of real-time baseband sinal processing in wide-band navigation software receivers.The thesis acclerates the acqusition module,bit sync module and tracking module by take advantage of the powerful computing capacity and the receiver finally achieve the high-speed performance of baseband signal processssing.The receiver can support the sampling rate which is no less than 50 MHz and the number of simultanenous tracking channels which no less than 20.The acquisition module parallels the search of doppler,carrier wipeing off,FFT and calculating the peak of correlation matrix.A method of rapid acquisition of navigation signals is implemented by adapting with the GPU software model.The bit synchronization module also adopts the strategy of paralleling the search of doppler and optimize the correlation operation using a method called parallel reduction.The paralled reduction can further be optimized by taking advatange of shared memorywhich the fast memory in GPU.Finally the receiver can achieve the real-time bit synchronization of single channel.The tracking module parallels the signal processing of different channels.The early,prompt and late C/A code correlation also adopts the parallel reduction strategy and shared memory.Because of the channel parallism and the E,P,L code parallisim,the parallsim of tracking module is high improved and the receiver eventually can tracking 20 channels simultaneously,which lays a good foundation for the realization of real-time interference monitoring function in wide-band GNSS software receivers.