紫外光通信系统中低速率语音编码技术研究
发布时间：2018-07-23 08:47
【摘要】：以紫外光作为通信载体的紫外光语音通信系统,以其对噪声极强抗干扰能力、保密性能好、非视距通信(Non Line of Sight,NLOS)和全天候通信等优点逐渐成为军事通信领域的研究焦点。但是,光通信领域又面临着信道资源有限和系统误码率高的问题,如何解决光通信中的问题,研究者主要从改进调制方式和进行信源编码两个方向进行攻关,其中以信源编码方式较为有效,研究高语音质量和低编码速率的编码方式成为光通信领域信源编码的重点。论文研究的目的是在参数编码的理论基础上,对特征参数进行提取,并在现场可编程逻辑阵列(FieldProgrammable Gate Array,FPGA)上实现,从而达到低速率语音编码的目的,编码后的数据加载到输出光波长为266 nm的紫外激光器上并调制输出,紫外光在大气中传播由光电倍增管接收并转换输出电流信号,电流信号被信号处理电路进行电流电压转换和放大处理,在FPGA开发板上对放大后的电压信号进行处理,完成解码工作,最终还原语音信号,从而实现高质量低速率紫外光语音通信。首先阐述了大气吸收效应和散射效应,进一步以瑞利散射和米氏散射为理论基础,建立了紫外光通信的单散射椭球模型。另外提出了参数编码中LPC-10编码算法,该算法能够在8 kHz的音频采集频率下,以180个样点为一帧,从而实现语音的编码速率为2.4 kb/s。在对语音进行线性预测分析时,重点研究了提取滤波器参数的理论推导,为参数编码奠定了理论模型。在对参数编码研究的同时,本文也给出了波形编码中较为典型的A律语音压缩编码的基本原理方法。针对系统的发射光源和光电探测器工作原理进行了简要介绍,同时对不同类型的光源和光电探测器进行了对比分析,最终确定发射光源选择紫外激光,光电探测器选择光电倍增管(Photomultiplier Tube,PMT)。使用FPGA开发板对数据流进行处理,根据FPGA的设计流程和编程原则,设计了串并转换、并串转换、RAM调用、参数计算、编码输出等底层模块,并对每个底层模块的功能进行相应的时序仿真和验证。搭建了两个通信系统,一个是验证A律编码的红光激光通信,另一个就是以LPC-10参数编码为核心的紫外光语音通信。并对以上两个语音通信系统在实验室进行了多次测试。测试结果表明,设计的A律编码的红光激光通信的语音编码速率为64 kb/s,客观平均意见得分(Mean Opinion Score,MOS)≥3.0,设计的LPC-10编码的紫外光语音通信的语音编码速率为2.4 kb/s,实现了中低速率语音编码通信。
[Abstract]:Ultraviolet (UV) voice communication system, with its strong anti-jamming ability to noise, good security performance, non-line-of-sight communication (NLOS) and all-weather communication, has gradually become the focus of research in the field of military communications. However, the field of optical communication is faced with the problems of limited channel resources and high bit error rate (BER). Among them, the source coding is more effective, and the research of high speech quality and low coding rate has become the focus of source coding in the field of optical communication. The purpose of this paper is to extract feature parameters based on the theory of parameter coding and implement them on Field Programmable Gate Array (FPGA), so as to achieve the purpose of low rate speech coding. The encoded data is loaded into the output wavelength of 266 nm UV laser and modulated. The ultraviolet light propagates in the atmosphere and is received by the photomultiplier tube and converted into the output current signal. The current signal is converted and amplified by the signal processing circuit, the amplified voltage signal is processed on the FPGA development board, the decoding work is completed, and the speech signal is finally restored. In order to achieve high quality low-rate UV voice communication. Firstly, the atmospheric absorption effect and scattering effect are described. Based on Rayleigh scattering and Michlet scattering theory, a single scattering ellipsoid model for ultraviolet communication is established. In addition, the LPC-10 coding algorithm in parameter coding is proposed. The algorithm can take 180 samples as a frame at 8 kHz audio acquisition frequency, thus the coding rate of speech is 2.4 kb / s. In the linear prediction analysis of speech, the theoretical derivation of extracting filter parameters is studied, which establishes a theoretical model for parameter coding. In addition to the research on parameter coding, this paper also gives the basic principle and method of A law speech compression coding, which is typical in waveform coding. This paper briefly introduces the working principle of the system's emitting light source and photodetector. At the same time, the different light sources and photodetectors are compared and analyzed. Finally, it is determined that the emitting light source should choose the ultraviolet laser. The photomultiplier PMT is selected by the photodetector. Using FPGA development board to process the data flow, according to the design flow and programming principle of FPGA, the bottom modules, such as serial-parallel conversion, parallel conversion RAM call, parameter calculation, encoding output and so on, are designed. And the function of each underlying module is simulated and verified. Two communication systems are built, one is the red laser communication which verifies A-law coding, the other is the ultraviolet voice communication based on LPC-10 parameter coding. The above two voice communication systems have been tested in the laboratory many times. The test results show that The speech coding rate of A law coded red light laser communication is 64 kb / s, the mean opinion score (MOS) is 鈮，
本文编号：2138857
[Abstract]:Ultraviolet (UV) voice communication system, with its strong anti-jamming ability to noise, good security performance, non-line-of-sight communication (NLOS) and all-weather communication, has gradually become the focus of research in the field of military communications. However, the field of optical communication is faced with the problems of limited channel resources and high bit error rate (BER). Among them, the source coding is more effective, and the research of high speech quality and low coding rate has become the focus of source coding in the field of optical communication. The purpose of this paper is to extract feature parameters based on the theory of parameter coding and implement them on Field Programmable Gate Array (FPGA), so as to achieve the purpose of low rate speech coding. The encoded data is loaded into the output wavelength of 266 nm UV laser and modulated. The ultraviolet light propagates in the atmosphere and is received by the photomultiplier tube and converted into the output current signal. The current signal is converted and amplified by the signal processing circuit, the amplified voltage signal is processed on the FPGA development board, the decoding work is completed, and the speech signal is finally restored. In order to achieve high quality low-rate UV voice communication. Firstly, the atmospheric absorption effect and scattering effect are described. Based on Rayleigh scattering and Michlet scattering theory, a single scattering ellipsoid model for ultraviolet communication is established. In addition, the LPC-10 coding algorithm in parameter coding is proposed. The algorithm can take 180 samples as a frame at 8 kHz audio acquisition frequency, thus the coding rate of speech is 2.4 kb / s. In the linear prediction analysis of speech, the theoretical derivation of extracting filter parameters is studied, which establishes a theoretical model for parameter coding. In addition to the research on parameter coding, this paper also gives the basic principle and method of A law speech compression coding, which is typical in waveform coding. This paper briefly introduces the working principle of the system's emitting light source and photodetector. At the same time, the different light sources and photodetectors are compared and analyzed. Finally, it is determined that the emitting light source should choose the ultraviolet laser. The photomultiplier PMT is selected by the photodetector. Using FPGA development board to process the data flow, according to the design flow and programming principle of FPGA, the bottom modules, such as serial-parallel conversion, parallel conversion RAM call, parameter calculation, encoding output and so on, are designed. And the function of each underlying module is simulated and verified. Two communication systems are built, one is the red laser communication which verifies A-law coding, the other is the ultraviolet voice communication based on LPC-10 parameter coding. The above two voice communication systems have been tested in the laboratory many times. The test results show that The speech coding rate of A law coded red light laser communication is 64 kb / s, the mean opinion score (MOS) is 鈮，
本文编号：2138857
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