一种低运算量GNSS接收机快速捕获方法

A fast acquisition method for GNSS receiver with low computational complexity

为了减少捕获阶段占用的时间与功耗,提出了一种低运算量的快速捕获方法。首先选取伪码周期整数倍数据进行二维重排,利用降采样理论对每个数据横块混叠;其次通过竖块FFT运算实现频率补偿以增强叠加信号的信噪比,使用横块FFT运算细化多普勒频移分辨率并得到特定的伪码相位筐,搜索特定筐内伪码相位的最大相关值。最后得到确切的伪码相位与多普勒频移。实际数据仿真结果表明,降采样因子与数据块个数取2时,所提方法运算效率是基于FFT捕获方法的4.1倍,基于SFT捕获方法的1.7倍,运算效率随降采样因子与数据块个数增大显著提升,能更好满足接收机的性能要求。

In order to reduce the time and power consumption of acquisition,a fast acquisition method with low computational complexity is proposed.Firstly,the integer multiples of the PRN’s period data are selected for two-dimensional rearrangement,and each data is aliased in horizontal blocks by using down-sampling theory.Secondly,vertical block FFT is used to compensate the frequency to enhance the SNR of the aliased signal,and horizontal block FFT is used to refine Doppler frequency shift resolution and obtain the PRN phase block,so as to find the max correlation value of the PRN phases in the block.Finally,the exact PRN phase and the Doppler frequency shift are obtained.The simulation of actual data shows that when the down-sampling factor and the number of data blocks are 2,the efficiency of the proposed method is 4.1 times of the FFT-based,and 1.7 times of the SFT-based acquisition method.The efficiency increases significantly with the increase of the down-sampling factor and the number of data blocks,which can better meet the performance requirements of GNSS receiver.