高抗噪性的SFFT-DT快速捕获算法

针对稀疏快速傅里叶变换（Sparse Fast Fourier Transform，SFFT）并行码相位捕获算法抗噪性能较差的问题，提出了一种新的高抗噪性快速捕获算法。该算法依据伪码相关函数峰值唯一的特点，利用降采样快速傅里叶变换（Downsampling Fast Fourier Transform，DFFT）取代了SFFT并行码相位捕获算法中对噪声容忍能力较差的定位循环与估值循环过程来对伪码相位进行捕获，同时对算法参数进行了优化设计。理论分析及仿真结果表明，与已有的SFFT快速捕获算法相比，SFFT-DT（Combination of SFFT and DFFT）捕获算法的计算速度提升了约19%，抗噪性能提升了约5 dB。与经典的FFT捕获算法相比，当两者抗噪性能近似相同（捕获概率大于95%的前提下）时，本文算法计算量比其减少了约43%。 

Fast Acquisition Algorithm with High Anti-Noise Performance Based on SFFT-DT

Aiming at the problem of poor anti-noise performance of Sparse Fast Fourier Transform parallel code phase capture algorithm， a new fast capture algorithm with high noise immunity is proposed. Based on the feature that the pseudo-code correlation function has only one large value point， the algorithm uses Downsampling Fast Fourier Transform（DFFT） to replace the positioning loop and the estimation loop process in the SFFT parallel code phase capture algorithm， which are less tolerant to noise. The algorithm parameters are optimized. Theoretical analysis and simulation results show that， compared with the existing SFFT capture algorithm， the calculation speed of the SFFT-DT capture algorithm is increased by about 19%， the anti-noise performance is improved by about 5 dB. Compared with the classic FFT capture algorithm， when the two anti-noise performances are approximately the same （under the premise that the capture probability is greater than 95%）， the calculation amount of the algorithm in this paper is reduced by about 43%.