低旁瓣多相编码脉冲压缩“波形─—滤波器对”及其抗噪性能

Low Sidelobe Polyphase Coded Pulse Compression“Waveform filter Pairs”and Their Performance in an AGWN Environment

本文在研究Ｐ＿３码和Ｐ＿４码序列对称特性的基础上，提出了两种实现低距离旁瓣的多相编码脉冲压缩“波形—滤波器对”，其中的滤波器参考码序列长度等于发射码序列长度，而且发射波形的包络是恒定的。在多普勒频移ｆ＿ｄ＝０的条件下，这两种“波形—滤波器对”的互相关函数的主旁瓣比接近或等于码序列的长度。另外，互模糊函数的研究结果表明，两种“滤形—滤波器对”具有比较理想的多普勒特性，在ｆ＿ｄ＝０～０．０５Ｂ的范围内，脉压结果的旁瓣几乎不增高，主瓣幅度起伏分别为２．１０ｄＢ和１．４４ｄＢ，平均ＳＮＲ损失为１．６２ｄＢ和２．２４ｄＢ。

In this paper,we first investigate the symmetric properties of P_3code and P_4code sequences,then,on the basis of the results obtained, we design two kinds of low range sidelobe polyphase coded pulsecompression“waveform-filter pairs”in which the length of the filter reference code sequence is equal to thelength of the transmitted waveform code sequence As far as MPSR(mainlobe to peak sidelobe ratio)is con-cerned, our designed“waveform-filter pairs”are equivalent to polyphase barker coded waveform,that is,theMPSR is equal to the length of the code sequence. With the help of the simulation of cross ambiguityfunction of the“waveform-filter pairs”,we investigate the Doppler property and the performance of the“waveform-filter pairs”in an additive White gaussian noise(AWGN)envionment from a detectionstandpoint. The results obtained indicate that the“waveform-filter pairs”have perfect Doppler property rela-tively.The simulation results also illustrate that within the limits of Doppler frequency from zero to 0.05B theaverage SNR loss of the two kinds“waveform-filter pairs”are 1.62dB and 2.24dB compared with matchedfilter processing, respectively.