一种水声宽带双曲调频信号波达方向估计方法

A DOA estimation method for underwater wideband HFM signals

提出了一种基于短时分数阶傅里叶变换的水下宽带双曲调频信号波达方向估计方法.建立了均匀线列阵声呐远场宽带双曲调频信号接收数据模型,在时域将接收信号进行分时段处理,对每一段短时信号分别进行分数阶傅里叶变换,将时域阵列接收数据转化成多段短时分数阶傅里叶域阵列数据,同时将多个时段的时变阵列流形矩阵变换成与每个时段一一对应的多个固定阵列流形矩阵.利用多重信号分类算法估计各短时信号的空间谱,应用求和运算进一步得到整体时段双曲调频信号空间谱,通过谱峰搜索实现对双曲调频信号的波达方向估计.通过仿真实验与分析,对该方法的水声双曲调频信号波达方向估计的有效性进行了验证,分析了该方法在阵列接收信号时域分段数、信噪比、目标方位等参数变化条件下的性能.与传统方法相比,该方法具有更高的方位分辨率和估计精度.

A method of estimating the direction of arrival（DOA）for underwater wideband hyperbolic frequency modulation（HFM）signal is proposed based on short-time fractional Fourier transform.The received wideband HFM signal data model of uniform linear array sonar in the far field is established.The received signal is divided into multiple short-time signals in time domain and fractional Fourier transform is applied to transform the traditional array data into a short-time fractional Fourier domain array data.At the same time,the time-varying array manifold matrix is correspondingly transformed into a fixed array manifold matrix.The spatial spectrum of each shorttime signal is estimated by the multiple signal classification（MUSIC）algorithm,and the HFM signal spatial spectrum of the whole time is further obtained by summation operation.Finally,DOA estimation of HFM signals is realized through spectral peak search.The effectiveness of the method to estimate the DOA of underwater HFM signals is verified by simulation experiments and the influence of time domain segmentation number,SNR and sound source orientation on the performance of the method is mainly studied.Compared with the traditional method,this method has higher azimuth resolution and estimation accuracy.