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针对低频水表面声波(WSAW)的频率识别问题,提出了一种基于改进相位生成载波(PGC)解调的激光相干探测方法。利用简单的激光干涉系统探测水下声源激发的低频WSAW,再利用4路载波信号对其进行混频,通过功率比较遴选出2路功率最大的正交干涉信号,然后进行相位解调和频谱分析,实现了WSAW的频率测定。仿真和实验研究表明,改进的PGC解调法能够有效防止载波信号初始相位不可控条件下的正交信号消隐并准确实现低频WSAW的频率识别(频率探测下限可达30 Hz),对变频WSAW及大尺度扰动波干扰条件下的低频WSAW也取得了很好的检测效果。该研究结果表明改进的PGC解调方法能够准确实现WSAW的频率识别,并具有很强的抗干扰能力。
Aiming at the problem of frequency identification of low frequency water surface acoustic wave (WSAW), a laser coherent detection method based on improved phase-generated carrier (PGC) demodulation is proposed. A simple laser interferometer system is used to detect the low frequency WSAW excited by the underwater sound source and then mixed with 4 carrier signals. Two orthogonal interference signals with the largest power are selected by power comparison, and then the phase demodulation and spectrum Analysis, to achieve the WSAW frequency determination. Simulation and experimental results show that the improved PGC demodulation method can effectively prevent the orthogonal signal blanking under the condition that the initial phase of carrier signal is uncontrollable and accurately identify the frequency of low-frequency WSAW (the lower limit of frequency detection is up to 30 Hz) And low-frequency WSAW under large-scale disturbing wave interference has also achieved good detection results. The results show that the improved PGC demodulation method can accurately identify the frequency of WSAW and has strong anti-interference ability.