基于改进循环谱的直扩信号检测方法研究

基于循环谱理论，根据直扩信号与平稳噪声具有不同的谱相关特性，可对直扩信号进行检测，分析循环谱包络在循环频域——谱频域上的分布，能实现载频及伪码速率的参数估计。在有限时间条件下，为实现更低信噪比情况下的信号检测，提出了集平均的频域平滑循环周期图的改进算法，避免了多维搜索，并对算法进行抗噪声性能及统计特性分析，理论表明具有进一步的抑制噪声水平。通过计算机仿真，说明了此法能在低信噪比情况下实现参数估计，并分别证明了数据长度及平滑点数对实验数据的影响，验证了理论分析的正确性。

A Research on Detection of DSSS Signal based on Improved Cyclic Spectrum

Based on cyclic spectrum theory, property of spectral correlation for DSSS signal and stationary noise is analyzed. Based on characteristics, DSSS signal can be detected, and the carrier frequency and chip rate can be estimated in distribution of cyclic frequency domain and spectral frequency domain based on cyclic spectrum envelope. In the condition of limited time, this paper proposed time-limited segment-average frequency-smoothed cyclic periodogram algorithm in order to avoid multidimensional searching, and discuss the algorithm against noise and statistical properties. Theory suggests that it suppress the noise level further. By computer simulation, the algorithm achieved estimation under low SNR, and certificated data length and smooth points influence on experimental results, and proved the correctness of theoretical analysis.