本文選題：激光 + 水下聲源��； 參考：《煙臺大學(xué)》2017年碩士論文

【摘要】：本文采用激光干涉法設(shè)計光路和搭建實驗平臺,對水下聲信號提取進行了實驗探索,驗證了激光相干探測水下聲源的可行性。實驗對自然水面波動情況進行了提取,并對三組不同位置、不同頻率以及不同振幅的數(shù)據(jù)進行了對比分析。同時,針對信號特征微弱的問題,本課題在傳統(tǒng)頻譜分析的基礎(chǔ)上,分別采用了濾波、短時傅里葉變換、小波分析、Wigner-Ville分布以及時頻分布的重排等時頻分析手段,以實現(xiàn)信號降噪和特征信號增強。實驗結(jié)果表明:(1)水面自然波動頻率主要集中在500 Hz以下的低頻區(qū),水面波動頻率范圍的確定為進一步的濾波降噪和時頻分析等提供了參考,也便于將水面自然波動頻率同特征信號頻率區(qū)分。(2)三組設(shè)定條件的數(shù)據(jù)采集和分析結(jié)果表明:距離探測位置越遠(yuǎn),信號衰減越嚴(yán)重。相同頻率的水下?lián)P聲器設(shè)備,隨著輸入幅值的增大,可探測到的信號強度明顯增強。輸入幅值一定時,頻率越高,信號強度越微弱。(3)在特征信號微弱的情況下,對采集的數(shù)據(jù)直接做傅里葉變換,特征信號不明顯,容易淹沒在背景中。采用濾波和小波分析等頻譜分析方法處理后,噪聲信號可以得到有效的濾除,特征信號增強明顯。(4)頻譜分析結(jié)果只能得到某一時刻各個頻率分量的相對強度分布,為了實現(xiàn)觀察一段時間內(nèi)頻率隨時間的變化情況的目的,本課題采用了短時傅里葉變換、譜圖以及Wigner-Ville分布等時頻分析方法。針對二次型時頻分布方法存在的交叉項等問題,本文采用增加窗口函數(shù)的方法來抑制交叉項。為了增加時頻聚集性,本文對數(shù)據(jù)做了時頻分布的重排。結(jié)果表明:交叉項干擾得到了相當(dāng)程度的抑制,時頻聚集性顯著改善。該系統(tǒng)采用光纖型的實驗裝置,避免了光路暴露在空氣中,大大減少了外界環(huán)境的影響。
[Abstract]:In this paper, the laser interference method is used to design the optical path and build the experimental platform. The experimental exploration of underwater acoustic signal extraction is carried out, and the feasibility of laser coherent detection of underwater acoustic source is verified. Three groups of data of different positions, frequencies and amplitudes were compared and analyzed. At the same time, aiming at the problem of weak signal characteristics, based on the traditional spectrum analysis, the paper adopts filtering, short-time Fourier transform, wavelet analysis and Wigner-Ville distribution to rearrange the time-frequency distribution. In order to achieve signal noise reduction and feature signal enhancement. The experimental results show that the natural wave frequency of water surface is mainly concentrated in the low frequency region below 500 Hz. The determination of the frequency range of water surface fluctuation provides a reference for further filtering noise reduction and time-frequency analysis. It is also convenient to distinguish the natural wave frequency of water surface from the frequency of characteristic signal. The results of data acquisition and analysis of three set conditions show that the farther away from the detecting position, the more serious the attenuation of the signal is. With the increase of input amplitude, the detectable signal intensity of the same frequency underwater loudspeaker equipment is obviously enhanced. When the input amplitude is constant, the higher the frequency is, the weaker the signal intensity is.) when the characteristic signal is weak, the collected data is directly transformed by Fourier transform, and the characteristic signal is not obvious and easily submerged in the background. The noise signal can be effectively filtered by using the methods of filtering and wavelet analysis, and the characteristic signal can be enhanced obviously. The spectrum analysis results can only obtain the relative intensity distribution of each frequency component at a certain time. In order to observe the change of frequency with time in a certain period of time, the methods of time-frequency analysis, such as short time Fourier transform, spectrum diagram and Wigner-Ville distribution, are adopted in this paper. Aiming at the problems of crossover terms in quadratic time-frequency distribution method, this paper uses the method of adding window function to suppress the crossover term. In order to increase the time-frequency aggregation, the time-frequency distribution of the data is rearranged. The results show that the cross term interference is suppressed to a certain extent and the time-frequency aggregation is improved significantly. The optical fiber type experimental device is used in the system, which avoids the exposure of the light path to the air and greatly reduces the influence of the external environment.
【學(xué)位授予單位】：煙臺大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB56

【參考文獻】

相關(guān)期刊論文 前10條

1 戴前偉;吳鎧均;張彬;;短時傅里葉變換在GPR數(shù)據(jù)解釋中的應(yīng)用[J];物探與化探;2016年06期

2 陳世哲;張曉琳;王波;趙維杰;張可可;趙強;吳玉尚;;激光-聲聯(lián)合探測中水表面聲波檢測方法進展[J];海洋技術(shù)學(xué)報;2016年03期

3 王玉明;王文成;韓鵬斌;;低頻水下聲信號調(diào)制下衍射光場的分布[J];光學(xué)儀器;2015年04期

4 文洪濤;楊燕明;周鴻濤;劉貞文;鄭凌虹;;海洋水下聲探測信號的分類與分析[J];應(yīng)用海洋學(xué)學(xué)報;2015年02期

5 徐健;張語R，

本文編號：1947554