双谱估计法在海底钴结壳微地形探测中的应用

THE APPLICATION OF THE BISPECTRUM METHOD TO THE MICROTOPOGRAPHIC MEASUREMENT OF Co-RICH CRUST AT THE OCEAN BOTTOM

海洋环境中水下超声测量系统往往因环境中机械噪声、背景噪声以及混响等强噪声而导致测距精度低,因而具有一定局限性。双谱的时延估计方法对高斯噪声具有屏蔽能力,能更好地压制噪声,并准确估计信号的时间延迟,且双谱功率谱重构要比直接用FFT变换方法估计功率谱具有更好的性能。利用双谱估计对背景噪声不敏感的特性来处理超声回波信号,根据实验室水池实测数据,验证了该方法的适用性。研究结果表明:在先验知识较少和背景噪声较强时双谱法比广义互相关法的适用性更好。

Under the actual marine environment,the underwater ultrasonic measurement system has a certain limitation because of mechanical noises such as background noise and reverberation noise.The bispectrum time delay estimation method with Gaussian noise has shielding capacity and is capable of suppressing noise.This method adopts an accurate estimation of the signal time delay,and its power spectral bispectrum reconstruction is superior to the direct use of FFT transform power spectrum estimation,thus having relatively high precision and performance.In view of underwater ultrasonic detection deficiencies,the bispectrum estimation method is adopted due to its insensitivity to background noise.According to measured data obtained in laboratory pool,the applicability of the method is verified.The results show that the bispectrum method has better applicability than the cross-correlation method under the conditions of less prior knowledge and strong background noise.