【摘要】：光纖空氣聲波傳感器相對(duì)于傳統(tǒng)的電麥克風(fēng)具有靈敏度高,測(cè)量動(dòng)態(tài)范圍廣,抗干擾能力強(qiáng)的優(yōu)點(diǎn),滿(mǎn)足在環(huán)境條件惡劣的情況下,對(duì)聲波信號(hào)高質(zhì)量檢測(cè),目前對(duì)光纖聲波傳感器的研究已成為光纖傳感領(lǐng)域的研究熱點(diǎn)之一。本文針對(duì)基于法布里-珀羅干涉型結(jié)構(gòu)的光纖麥克風(fēng),對(duì)其解調(diào)方法和解調(diào)性能等方面進(jìn)行了研究,主要內(nèi)容如下：1.詳細(xì)分析理想相位生成載波(Phase Generated Carrier,簡(jiǎn)稱(chēng)PGC)算法,利用Simulink仿真工具,驗(yàn)證算法的可行性。確定調(diào)制頻率、采樣率、濾波器過(guò)渡帶寬與解調(diào)動(dòng)態(tài)范圍之間的關(guān)系,并通過(guò)大量數(shù)據(jù)仿真,驗(yàn)證關(guān)系的正確性。2.針對(duì)工程應(yīng)用中,采用DFB(Distributed Feed Back)激光器的光頻內(nèi)調(diào)制方案,利用理想的PGC解調(diào)方法,解調(diào)信號(hào)出現(xiàn)多次諧波問(wèn)題。經(jīng)過(guò)分析,提出利用載波二倍和三倍載波頻率來(lái)解調(diào)信號(hào)的改進(jìn)方案,消除多次諧波。另外,通過(guò)相位補(bǔ)償,解決系統(tǒng)延時(shí)對(duì)解調(diào)信號(hào)的影響。在多頻解調(diào)情況下,驗(yàn)證解調(diào)信號(hào)滿(mǎn)足群延時(shí)特性。3.制作光纖麥克風(fēng)解調(diào)系統(tǒng)硬件電路,編寫(xiě)FPGA(Field Programmable Gate Array)底層驅(qū)動(dòng)程序和DSP(Digital Signal Processing)算法。激光器驅(qū)動(dòng)電路對(duì)激光器的工作電流和溫度嚴(yán)格限制,保護(hù)激光器不受損壞。核心控制電路采集數(shù)據(jù)、進(jìn)行算法處理、輸出音頻信號(hào),嚴(yán)格控制時(shí)序,實(shí)時(shí)解調(diào)。4.對(duì)光纖麥克風(fēng)解調(diào)系統(tǒng)的各方面性能進(jìn)行測(cè)試,測(cè)得音頻輸出信號(hào)系統(tǒng)線性響應(yīng)度良好,線性響應(yīng)誤差為0.21%；在3kHz-10kHz范圍內(nèi),系統(tǒng)頻率響應(yīng)誤差小于3dB;系統(tǒng)在1kHz處,能檢測(cè)的最小聲壓為2mPa,即-54dB@1kHz。實(shí)驗(yàn)結(jié)果表明,此套麥克風(fēng)信號(hào)解調(diào)系統(tǒng)能滿(mǎn)足基本的聲波信號(hào)測(cè)量要求。
[Abstract]:Compared with the traditional electric microphone, the fiber optic air acoustic sensor has the advantages of high sensitivity, wide dynamic range of measurement and strong anti-interference ability. At present, the research of optical fiber acoustic sensor has become one of the research hotspots in the field of optical fiber sensing. In this paper, the demodulation method and demodulation performance of fiber optic microphone based on Fabry-Perot interference structure are studied. The main contents are as follows: 1. The ideal phase generation carrier (Phase Generated Carrier, (PGC) algorithm is analyzed in detail. The feasibility of the algorithm is verified by Simulink simulation tool. The relationship between modulation frequency, sampling rate, filter bandwidth and demodulation dynamic range is determined, and the correctness of the relationship is verified by a large number of data simulations. 2. In view of the engineering application, the problem of multiple harmonics in demodulation signal is caused by adopting the optical intracavity modulation scheme of DFB (Distributed Feed Back) laser and using the ideal PGC demodulation method. After analysis, an improved scheme of demodulating signals with double and triple carrier frequencies is proposed to eliminate multiple harmonics. In addition, the effect of system delay on demodulation signal is solved by phase compensation. In the case of multi-frequency demodulation, it is verified that the demodulation signal meets the group delay characteristics. 3. Make the hardware circuit of fiber optic microphone demodulation system, write FPGA (Field Programmable Gate Array) bottom driver and DSP (Digital Signal Processing) algorithm. The laser drive circuit strictly limits the operating current and temperature of the laser and protects the laser from damage. Core control circuit data acquisition, algorithm processing, output audio signal, strict control of timing, real-time demodulation. 4. The performance of fiber optic microphone demodulation system is tested. The linear responsivity of audio output signal system is good, the linear response error is 0.21, the frequency response error is less than 3 dB in 3kHz-10kHz range, and the system is at 1kHz. The minimum detectable sound pressure is 2mPa-54dB@ 1kHz. Experimental results show that the microphone signal demodulation system can meet the basic requirements of acoustic signal measurement.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TN253;TN641

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本文編號(hào)：2282197