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针对浅海近距离时倒谱多径时延峰变弱难以提取的问题,提出了一种功率谱加权自相关多径时延估计方法。该方法采用FFT估计信号功率谱,对功率谱取1-α次幂(0<α<1),再进行IFFT变换,对其实部进行峰值检测获得多径时延估计。根据目标能量通过特性在正横前递增正横后递减的特点,在已检测时延前后一定区间内搜索下一个时延值,实现多径时延的自动提取.理论分析表明,多径时延估计的倒谱法与自相关法都可以看作功率谱加权自相关法的特例.海试数据处理与基于Bellhop射线模型的仿真计算表明,该方法在近距离时多径时延峰比倒谱法更清晰,输出信噪比提高了3～4 dB.采用该方法自动提取的海底反射多径时延用于单个水听器对目标距离的估计,与GPS测量距离基本相符,验证了方法的有效性.
Aiming at the problem that the multipath delay peak of cepstral fractal spectrum becomes weaker and harder to extract at shallow sea near distance, a power spectral autocorrelation multipath delay estimation method is proposed. The method uses FFT to estimate the power spectrum of the signal, takes 1-α power (0 <α <1) for the power spectrum, and performs IFFT transform on the power spectrum to obtain the multipath time delay estimation. According to the characteristic that the target energy passes through the front of the target and increases descending in the horizontal direction, the next delay value is searched within a certain interval before and after the detected delay to realize the automatic extraction of the multipath delay. The theoretical analysis shows that the multipath delay Estimation of cepstrum and autocorrelation can be regarded as a special case of power spectral weighted autocorrelation.Seismic processing and Bellhop ray model based on the simulation results show that this method at close range multipath delay peak cepstrum Method is clearer and the output signal to noise ratio is increased by 3 ~ 4 dB. The submarine reflection multipath delay automatically extracted by this method is used to estimate the target distance of a single hydrophone, which is basically consistent with the GPS measurement distance, Effectiveness.