时频域并行捕获算法

针对DS/FH(Direct Sequence/Frequency Hopping)混合扩频测控信号的快速捕获,经典的时域并行方法或频域并行方法已不能满足需求.为了进一步提高载波捕获精度,在PMF-FFT(Partial Match Filter-Fast Fourier Transform)算法基础上,提出了一种反馈式结构的时频域并行捕获算法,通过PMF-FFT算法粗估载波频偏,利用一种Quinn频率插值算法提高频偏估计精度,并使用估计结果调整本地载波,再次进行捕获.理论分析和仿真结果表明,该算法与PMF-FFT算法相比,提高了载波捕获精度,在大频偏低信噪比条件下增加了频率分析带宽、减少了平均捕获时间.

Parallel acquisition algorithm in time-frequency domain

Due to the fact that the classic method of parallel acquisition in the time or frequency domain cannot satisfy the demand of the fast acquisition of the direct sequence/frequency hopping(DS/FH) hybrid spread spectrum signal in TT&C. In order to further improve the acquisition accuracy of the carrier, on the basis of the partial match filter-fast fourier transform(PMF-FFT) algorithm, a parallel algorithm in the time-frequency domain with feedback architecture was proposed. Through the coarse estimation of the carrier frequency offset by the PMF-FFT algorithm, the new algorithm uses the Quinn frequency interpolation algorithm to improve the estimation accuracy of frequency offset, modifying the local carrier by employing the estimated result and reacquiring. Theoretical analysis and simulation results show that, compared to the PMF-FFT algorithm, the new method improves acquisition accuracy of the carrier, under the conditions of large frequency offset and low SNR, increases the frequency analysis bandwidth, and reduces the average acquisition time.