平台运动引起Bragg海浪谱的展宽及其压缩方法

A Novel Method for Extracting Target Signal from Broadened

基于运动叠加原理，推导了以Ｄｏｐｐｌｅｒ频率表征的雷达平台运动条件下高频段海浪杂波的运动方程及由平台运动引起的Ｂｒａｇｇ海浪谱的展宽表达式；给出了受平台运动调制的Ｂｒａｇｇ海浪回波与目标信号在Ｄｏｐｐｌｅｒ域里的二阶模糊关系和运用ＳＴ－ＷＤ（ＳｈｏｒｔＴｉｍｅＡｖｅｒａｇｅＷｉｇｎｅｒ－ＶｉｌｅＤｉｓｔｒｉｂｕｔｉｏｎ：短时平均Ｗｉｇｎｅｒ－Ｗｉｌｅ分布）技术对一阶海浪回波信号的高频相位进行平滑处理的方法。在此基础上，提出了一种在展宽的一阶海浪谱中提取目标信号的方法—复解调技术。

Based on the motion-superposition principle, the effects of a moving radar platform on the first-order Bragg lines in ship-borne surface wave radar returns are analysised mathematically in terms of Doppler frequency and a distortion model which describes Bragg lines broadening due to the radar platform motion is presented. The ambiguity between broadened Bragg lines and ship echoes in Doppler domain is indicated implicitly and a method based on ST-WD(Short Time Average Wigner-Ville Distribution) for removing the random phase from the first-order Bragg returns is described. Finally, a complex demodulation technique for extracting the interesting of target signals from the broadened Bragg clutter is developed. Simulation results in ship-borne surface wave radar applications show that the broadened Bragg lines resulted from the motion of radar platform can be suppressed about 17-19dB by the complex demodulation method, which also means that the complex demodulation technique developed in this paper is more prospective to detect the targets embedded in the broadened Bragg clutter in ship-borne surface wave radar.