音频信号光反射调制的激光传输系统研制

发布时间：2018-10-07 21:08

【摘要】：由于音频信号在信息传递中的重要作用,使得音频信号的检测备受重视。目前音频信号检测常用的的方法是利用传声器检测和利用激光测振法检测。传声器检测要求音频信号距离传声器的距离不能太远,且音频信号与传声器间不能有封闭性的遮挡物,否则检测效果将大打则扣。因此,在声音源距离检测端较远或者有薄壁器物作为遮挡物的情况下则需用到激光测振法来检测。由于本系统研制的应用场景是基于远距离且声音源与检测端间有遮挡物,故采用激光测振方式。目前常用的激光测振技术包括激光多普勒参考光测振技术、外差多普勒测振技术、全息干涉法测振技术及光反射调制测振技术等。其中激光多普勒技术由于无法分辨振动方向,所以其无法测量随机振动,外差多普勒测振技术和全息干涉法测振技术克服了以上缺点,但是两者由于均采用干涉的方法,故对光路稳定性要求严格,且采用干涉时系统复杂,尤其是在室外环境使用时会有诸多不便。光反射调制测振技术采用反射的方法,其可测量随机振动,且对光路稳定性要求较干涉有所降低,系统的复杂性也有所降低,因此结合应用需求本系统采用了光反射调制测振技术。本文研制了音频信号光反射调制的激光传输系统,采用了激光发射系统和接收系统分立设计的思想,这样极大地增强了系统使用的便利性及实用性,并在检测到音频信号并存储后对带有噪声的音频信号进行了语音增强处理,处理后的音频信号无论清晰度还是可懂度都较为良好。本论文的主要工作总结如下。(1)完成了音频信号光反射调制的激光传输系统的设计与实现,实现了较远距离且声源与检测装置有遮挡时的音频信号检测,检测距离可达200m。(2)开展了对系统的测试与实验,包括:激光器性能的测试,如光斑大小、发散角及激光稳定度;系统参数的测试,如检测距离,灵敏度及频率响应范围;语音信号的检测,包括相对较易识别的语音信号数字1-10和较难识别的汉语话语。(3)完成了对检测的带有噪声的语音信号的语音增强处理,并采用MOS得分法和信噪比处理前后对比的方法对语音增强的效果进行了质量评价,结果较好。通过本文的工作,对采用激光反射式的方式检测音频信号提供了思路与借鉴,具有一定的意义。
[Abstract]:Due to the important role of audio signal in information transmission, the detection of audio signal is paid more attention. At present, the commonly used methods of audio signal detection are microphone detection and laser vibration detection. The detection of microphone requires that the distance between the audio signal and the microphone should not be too far, and there must be no blocking between the audio signal and the microphone, otherwise, the detection effect will be greatly reduced. Therefore, when the sound source is far from the detection end or has a thin wall object as a barrier, laser vibration detection method is needed to detect the sound source. Because the application scene of this system is based on the distance and there is an occlusion between the sound source and the detecting end, the laser vibration measurement method is adopted. At present, the commonly used laser vibration measurement techniques include laser Doppler reference light vibration measurement, heterodyne Doppler vibration measurement, holographic interferometry and light reflection modulation vibration measurement. The laser Doppler technique can not measure the random vibration because it can not distinguish the vibration direction. The heterodyne Doppler vibration measurement technique and the holographic interferometry technique overcome the above shortcomings, but both of them adopt the interference method. Therefore, the stability of optical path is strict, and the system is complex when it is used in interference, especially in outdoor environment. The method of light reflection modulation is used to measure random vibration, and the requirement of optical path stability is lower than that of interference, and the complexity of the system is also reduced. Therefore, the system adopts the light reflection modulation vibration measurement technology combined with the application requirements. In this paper, a laser transmission system with optical reflection modulation of audio signal is developed. The design of laser transmitting system and receiving system is adopted, which greatly enhances the convenience and practicability of the system. After the audio signal is detected and stored, the speech enhancement of the audio signal with noise is carried out. The processed audio signal has good clarity and intelligibility. The main work of this paper is summarized as follows: (1) the design and implementation of the laser transmission system of audio signal and optical reflection modulation is completed, and the audio signal detection is realized when the sound source and detection device are occluded. (2) testing and experiment of the system are carried out, including: laser performance test, such as spot size, divergence angle and laser stability, system parameter test, such as detection distance, sensitivity and frequency response range; The detection of speech signals includes relatively easily recognizable speech signal numbers 1-10 and more difficult to recognize Chinese utterances. (3) speech enhancement processing of the detected speech signals with noise is completed. The effect of speech enhancement is evaluated by MOS score method and comparison of signal to noise ratio before and after processing, and the result is good. Through the work of this paper, the method and reference of detecting audio signal by laser reflection mode are provided, which is of certain significance.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN249

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