基于FRFT的Chirp水声扩频通信技术研究
发布时间：2018-10-09 09:26
【摘要】：浅海水声信道是一个极其复杂的无线信道,其信道参数随着时-空-频的变化而随机变化,存在强多径干扰、带宽窄、随机噪声和多普勒频移等特征,要在这样环境恶劣的信道下,实现可靠和有效的通信传输面临着巨大的挑战。所以研究一种可以抵抗低信噪比、多径衰落以及多普勒频移等影响,仍能保证一定信息传输速率的可靠传输技术是十分必要的。 本文研究了基于Chirp信号的水声扩频通信技术,具有很好的抗噪性能和抗多径特性。首先提出一种基于Chirp信号的帧同步结构,验证了该帧同步优异的同步性能,保证了通信系统接收端的正确解调。接着研究基于分数阶傅里叶变换(FRFT)解调的Chirp单载波与多载波的调制系统,以及利用去斜压缩解调的Chirp扫频-扩频系统。在上述系统理论仿真的基础上,将各个通信系统的调制解调集成到设计的Matlab GUI界面上。最后对通信系统进行加噪测试、水池多径实验及海测实验,验证本文所设计的通信系统的抗噪性能和抗多径特性,实验结果表示,基于Chirp信号的扩频通信系统具有较好的抗噪和抗多径性能。论文的主要工作如下： 1.系统地介绍国内外Chirp扩频技术的发展现状和研究概况。 2.并提出一种适用于水声通信的帧同步结构,仿真测试在不同信道条件下的同步性能。 3.系统介绍Chirp扩频技术,对Chirp单载波的高阶调制技术进行研究,接收端采用FRFT解调,为抵抗多径信道的频率选择性衰落,提出基于多载波技术的Chirp扩频调制技术,对比分析Chirp单载波与多载波的系统性能。 4.针对水声强多径的特点,研究一种抗多径的Chirp扫频-扩频系统,分析不同信道参数对系统的影响,并提出了一种结合FRFT解调的MFSK-Chirp扫频-扩频系统,进一步提高系统的传输速率。 5.在上述理论分析和仿真测试基础上,将通信系统集成到Matlab GUI界面,进行抗噪测试、水池多径实验和海洋测试实验,验证系统性能。
[Abstract]:Shallow underwater acoustic channel is an extremely complex wireless channel. Its channel parameters change randomly with the change of time-space-frequency, which has the characteristics of strong multipath interference, narrow band, random noise and Doppler shift. In such a bad environment, reliable and effective communication transmission is facing a great challenge. Therefore, it is necessary to study a reliable transmission technology which can resist the influence of low signal-to-noise ratio, multipath fading and Doppler frequency shift, and can still guarantee a certain rate of information transmission. In this paper, the underwater acoustic spread spectrum communication technology based on Chirp signal is studied, which has good anti-noise performance and anti-multipath characteristic. Firstly, a frame synchronization structure based on Chirp signal is proposed, which verifies the excellent synchronization performance of the frame synchronization and ensures the correct demodulation of the receiver of the communication system. Then the Chirp single carrier and multi-carrier modulation system based on fractional Fourier transform (FRFT) demodulation and the Chirp sweep-spread spectrum system based on de-skew compression demodulation are studied. Based on the theoretical simulation of the above system, the modulation and demodulation of each communication system is integrated into the designed Matlab GUI interface. Finally, the anti-noise performance and anti-multipath characteristic of the communication system designed in this paper are verified by the noise-adding test, the multi-path experiment and the sea survey experiment. The experimental results show that, The spread spectrum communication system based on Chirp signal has better anti-noise and anti-multipath performance. The main work of this paper is as follows: 1. This paper systematically introduces the development and research situation of Chirp spread spectrum technology at home and abroad. 2. A frame synchronization structure suitable for underwater acoustic communication is proposed, and the synchronization performance under different channel conditions is tested by simulation. 3. The Chirp spread spectrum technology is introduced systematically, and the high-order modulation technology of Chirp single carrier is studied. In order to resist the frequency selective fading of multipath channel, the FRFT demodulation is adopted in the receiver. In order to resist the frequency selective fading of multipath channel, the Chirp spread spectrum modulation technology based on multi-carrier technology is proposed. The system performance of Chirp single carrier and multi-carrier is compared and analyzed. 4. According to the characteristics of underwater acoustic intensity multipath, a kind of anti-multipath Chirp sweep-spread spectrum system is studied. The influence of different channel parameters on the system is analyzed, and a kind of MFSK-Chirp sweep-spread spectrum system combined with FRFT demodulation is proposed to further improve the transmission rate of the system. 5. Based on the above theoretical analysis and simulation test, the communication system is integrated into the Matlab GUI interface, and the anti-noise test, the multi-path experiment in the pool and the experiment in the ocean are carried out to verify the performance of the system.
【学位授予单位】：厦门大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.3
本文编号：2258836
[Abstract]:Shallow underwater acoustic channel is an extremely complex wireless channel. Its channel parameters change randomly with the change of time-space-frequency, which has the characteristics of strong multipath interference, narrow band, random noise and Doppler shift. In such a bad environment, reliable and effective communication transmission is facing a great challenge. Therefore, it is necessary to study a reliable transmission technology which can resist the influence of low signal-to-noise ratio, multipath fading and Doppler frequency shift, and can still guarantee a certain rate of information transmission. In this paper, the underwater acoustic spread spectrum communication technology based on Chirp signal is studied, which has good anti-noise performance and anti-multipath characteristic. Firstly, a frame synchronization structure based on Chirp signal is proposed, which verifies the excellent synchronization performance of the frame synchronization and ensures the correct demodulation of the receiver of the communication system. Then the Chirp single carrier and multi-carrier modulation system based on fractional Fourier transform (FRFT) demodulation and the Chirp sweep-spread spectrum system based on de-skew compression demodulation are studied. Based on the theoretical simulation of the above system, the modulation and demodulation of each communication system is integrated into the designed Matlab GUI interface. Finally, the anti-noise performance and anti-multipath characteristic of the communication system designed in this paper are verified by the noise-adding test, the multi-path experiment and the sea survey experiment. The experimental results show that, The spread spectrum communication system based on Chirp signal has better anti-noise and anti-multipath performance. The main work of this paper is as follows: 1. This paper systematically introduces the development and research situation of Chirp spread spectrum technology at home and abroad. 2. A frame synchronization structure suitable for underwater acoustic communication is proposed, and the synchronization performance under different channel conditions is tested by simulation. 3. The Chirp spread spectrum technology is introduced systematically, and the high-order modulation technology of Chirp single carrier is studied. In order to resist the frequency selective fading of multipath channel, the FRFT demodulation is adopted in the receiver. In order to resist the frequency selective fading of multipath channel, the Chirp spread spectrum modulation technology based on multi-carrier technology is proposed. The system performance of Chirp single carrier and multi-carrier is compared and analyzed. 4. According to the characteristics of underwater acoustic intensity multipath, a kind of anti-multipath Chirp sweep-spread spectrum system is studied. The influence of different channel parameters on the system is analyzed, and a kind of MFSK-Chirp sweep-spread spectrum system combined with FRFT demodulation is proposed to further improve the transmission rate of the system. 5. Based on the above theoretical analysis and simulation test, the communication system is integrated into the Matlab GUI interface, and the anti-noise test, the multi-path experiment in the pool and the experiment in the ocean are carried out to verify the performance of the system.
【学位授予单位】：厦门大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.3
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