基于MDBZP的微弱扩频信号捕获方法研究

Research on Acquisition Algorithm for Weak DSSS Signal Based on MDBZP Method

扩频接收机中微弱信号捕获是个难点。针对传统捕获算法对微弱扩频信号捕获概率低、分辨率不高的问题,引入常应用于捕获GPS信号的改进的双块零拓展MDBZP算法,并创新性地对其进行改进和参数优化,提出适用于扩频接收机的M^2DBZP(modified MDBZP)算法。根据M^2DBZP算法提供的数据分块组合和补零原则,仅需要较小的计算量就可以完成长时间相干积分和未知数据跳变处理。仿真结果表明,当数据码率为5 kb/s时,M^2DBZP算法能精确地捕获信噪比低至-40 dB的微弱扩频信号,且具有较高的分辨率,伪码相位精确到采样点。还验证了M^2DBZP算法针对不同码率的普遍适应性。与传统单频域并行捕获算法相比,在捕获分辨率相同的情况下,M^2DBZP算法的计算量减少了约86%。

Acquisition of the weak signal is a focal point in DSSS signal receiving.The performance of conventional solutions cannot meet the needs of fast acquisition of DSSS signals at low signal-to-noise ratio（SNR）.To solve this problem,this paper introduces the modified double block zero padding（MDBZP） method which is often used in GPS signal acquisition.By improving the procedure and optimizing the parameters,a modified algorithm for spread spectrum telemetry signal,which is named M2 DBZP,is used on the spread spectrum receiver for the first time.The algorithm makes it possible to calculate long-term coherent integration and data reverse with less computation burden.Simulation and test results show the excellent performance and flexibility of the proposed algorithm when the code rate of the signal is 5kb/s and the SNR is as low as-40 dB.Compared with the FFT-based parallel acquisition algorithm,the M2 DBZP algorithm reduces the computation cost by 86%on the same precision of Doppler frequency or phase of the PN code.