匹配场处理舰船辐射噪声级估计方法

An estimation method of ship radiated noise level based on matched field processing

针对水声信道对舰船辐射噪声声传播的影响,进而导致声源级测量结果不准确的问题,提出了基于匹配场处理的舰船辐射噪声级估计方法。在海洋环境噪声为空间均匀高斯白噪声的假设下,当海洋环境参数已知、信噪比满足一定要求时,匹配场处理能有效地给出被测噪声源的位置信息及该位置处的能量响应。从能量估计角度出发,推导了声源位置处匹配场输出响应的能量修正因子计算公式,从理论上证明了匹配场处理在被测声源位置处输出响应与能量修正因子的乘积为真实声源级的最小方差无偏(MVU)估计。该方法首先选择合适的声场计算模型计算拷贝场向量,对接收到的辐射噪声信号进行匹配场处理,得出接收信号级和被测声源位置;其次利用该位置所对应的拷贝场向量替换能量修正因子公式中的真实信道传输函数以计算能量修正因子的估计值;最后由接收信号级与能量修正因子估计值相乘得出舰船辐射噪声声源级的MVU估计。针对典型的浅海水声信道,进行了计算机仿真试验,结果表明:该方法能有效地进行舰船辐射噪声测量,当信噪比满足一定要求时,测量得到的声源级与实际声源级相比,误差小于1 dB。

An estimation method of the ship radiated noise level based on matching field processing （MFP） is proposed to decrease the measurement error caused by the propagation of the radiated noise in the complex underwater acoustic channel. Under the assumption that the ambient noise is temporally and spatially white Gaussian distributed, the location and the power spectrum response of the radiated noise source can be obtained while the ocean environment parameters are all known. A calculation formula of the power correction factor for the power response of the MFP at the location of the noise source is introduced, and the product of the power correction factor and the output power response of the MFP at the location of the radiated noise source is theoretically proved to be the minimum variance unbiased （MVU） estimation of the real source power. The processing steps of this method axe presented as follows： （1） the replica field vector can be calculated by appropriate acoustic field calculation model~ and the received source level （RSL） and the location of the measured ship can be obtained by MFP. （2） Utilizing the replica field vector at the location of the measured ship to replace the real channel transfer function to calculate the power correction factor. （3） The MVU estimation of the origin source level can be obtained by the product of the RSL and the power correction factor. Numerical simulations in a typical shallow water environment demonstrate the effectiveness of the proposed method. When the source to noise ratio satisfies a certain requirement, the difference between the source level estimated by proposed method and the origin source level is less than 1 dB.