船舶噪声信号常用解调方法分析

为了加深对绝对值解调以及Hilbert变换这2种解调方法的认识，对含有2个载频信号（从而可推广到宽频）的2种解调方法进行了较深层的理论研究，将DEMON分析用于对仿真信号进行频谱分析，并估计仿真信号中的谐波成分，进而比较不同方法的差异。理论分析及仿真结果表明，在一定条件下，无论是单频信号还是多频信号，其Hilbert变换都明显优于绝对值解调方法，但是所含载频越多，条件就越苛刻。本文的实验结果与理论相吻合。

Analysis of the Common Demodulation Method of Ship-Radiated Noise

In order to deepen the understanding about the methods of absolute-value-low-pass demodulation and Hilbert-transform demodulation,this paper provides a theoretical study on two demodulation methods containing the signals with two carrier frequency and this can be generalized to broadband.Meanwhile,by analyzing the spectrum of simulation signal,we estimate the harmonic composition,and then show the difference of the methods.The theoretical analysis and the simulation results indicate that,under certain condition,for both the single-frequency signal and the multiple-frequency signal,its Hilbert transformation will be quite better obviously than absolute-value-low-pass demodulation.However,the more it contains carrier frequency,the more rigorous its conditions will be.The simulation results coincide with the theory in this paper.