FrFT解线调浅剖信号增强算法及FPGA实现

FrFT dechirping sub-bottom profiling signal enhancement algorithm and FPGA implementation

针对浅剖信号带内噪声抑制问题,提出一种基于分数阶Fourier变换(FrFT)解线调理论的浅剖信号增强算法,在分数阶Fourier域(u域)去除chirp浅剖信号带内噪声与信号间的耦合,推导出任意时延chirp解线调信号u域的频率表达式,分析了解线调多途信号的u域频谱特征,并指出时间窗位置的选取不会影响算法性能,以此为理论依据联合时频域带通滤波和u域遮隔处理实现信号空间与噪声空间的分离,达到了提高带内信号信噪比的目的。计算机仿真实验验证了算法的有效性,并在1片FPGA上实时实现了该算法。

A sub-bottom profiling signal enhancement algorithm based on the fractional Fourier transform （FrFT） dechirping theory was proposed to restrain the intraband noise. The algorithm can remove the coupling of the intraband noise and signal in the fractional Fourier domain （u domain） , as a result the dechirping signal＇s frequency expression in the u domain with arbitrary time delay can be derived, The authors analyzed the u domain spectrum characteristics of the multi-path signal, and pointed out that the position selection of the time window would not affect the performance of this algorithm, And according to the results analyzed, the signal space and the noise space can be separated by associating time-frequency domain band-pass filtering and u domain masking, and the intraband SNR was increased. The availability of this algorithm was proved by the computer simulation, and this algorithm was implemented on one piece of the FPGA.