波导不变量误差对频域β-warping变换及浅海被动测距的影响

Influence of waveguide invariant error on β-warping transform and range estimation results in shallow water

频域β-warping变换可将接收信号自相关函数中简正波互相关部分,变为时域上时延随声源距离线性增大的脉冲序列。对信号自相关函数进行β-warping变换需要已知波导不变量值。但是,在实际应用中,很难获得波导不变量的准确值。研究表明,在事先获得粗略的水体声速剖面参数的情况下,如果估计得到的波导不变量为其真实值的q倍,那么频域β-warping变换后得到的脉冲时延也会变为波导不变量取真实值时的q倍。进一步研究表明,在水平不变浅海波导中采用频域β-warping变换进行被动测距时,通过设置一个已知距离的引导声源,那么即使估计得到的波导不变量存在一定误差,实际测距结果仍与真实距离符合得较好。

Theβ-warping operator can transform the cross-correlation functions of mode pairs in signal autocorrelation function into an impulsive sequence.However,it’s difficult to obtain the accurate value of the waveguide invariant.Theoretical analysis and simulations show that the pulse delay afterβ-warping is q times as the real one if the estimated waveguide invariant is q times as many as the real one with prior knowledge of sound speed profile parameters.For passive source range estimation usingβ-warping transform,when a guided source existing,the estimated ranges match well with the real ones,as long as the estimated waveguide invariant is within a reasonable range.