利用正弦调频信号的宽带速度敏感特性抑制混响
Reverberation suppression by utilizing wideband speed sensitive characteristic of sinusoidal frequency modulation signal
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摘要: 有源声呐探测水中低速目标时,混响与目标回波的频率接近,目标回波与混响分离困难。根据运动目标与产生混响的散射体在速度域的差异,利用正弦调频信号(SFM)的速度敏感特性实现目标回波与混响的有效分离。推导了 SFM信号宽带混响抑制能力与速度分辨模糊之间的约束关系,建立了波形优化设计的搜索模型。通过多普勒滤波处理将数据从频率域统一转换至速度域,设定合适的速度门限,去除静止的混响成分。通过仿真分析了 SFM信号的混响抑制能力、调制指数和带宽的关系,在设定的速度范围内平均混响抑制能力较连续波(CW)信号可提高7.5 dB。动目标试验数据的处理结果表明了该方法能够抑制混响中强杂波造成的虚警,通过速度差异性可有效提高对动目标的检测能力。Abstract: Reverberation is the main interference in the detection of underwater targets by active sonar,especially for low-speed target,whose echo frequency is close to that of reverberation.According to the velocity difference of scatters in the process of echo and reverberation,the effective separation of target echo and reverberation is realized by using the characteristics of Sinusoidal Frequency Modulation(SFM) signal.The constraint relation of wideband reverberation suppression and velocity resolution ambiguity was derived for SFM signal,the search model of waveform optimization was established.The data was transformed from frequency domain to speed domain through doppler filering,the reverberation can be reduced by setting an appropriate speed threshold.The relationship between reverberation suppression ability,modulation index and bandwidth of SFM signal is analyzed by simulation.The mean anti-reverberation performance of SFM signal is 7.5 dB better than that of Continuous Wave(CW) signal within the preset speed range.The processing results of moving target test data show that this method can suppress the false alarm caused by strong clutter component in reverberation.The detection ability of moving target can be improved by speed difference feature.