【摘要】：淺海水聲信道是一個(gè)極其復(fù)雜的無線信道,其信道參數(shù)隨著時(shí)-空-頻的變化而隨機(jī)變化,存在強(qiáng)多徑干擾、帶寬窄、隨機(jī)噪聲和多普勒頻移等特征,要在這樣環(huán)境惡劣的信道下,實(shí)現(xiàn)可靠和有效的通信傳輸面臨著巨大的挑戰(zhàn)。所以研究一種可以抵抗低信噪比、多徑衰落以及多普勒頻移等影響,仍能保證一定信息傳輸速率的可靠傳輸技術(shù)是十分必要的。 本文研究了基于Chirp信號(hào)的水聲擴(kuò)頻通信技術(shù),具有很好的抗噪性能和抗多徑特性。首先提出一種基于Chirp信號(hào)的幀同步結(jié)構(gòu),驗(yàn)證了該幀同步優(yōu)異的同步性能,保證了通信系統(tǒng)接收端的正確解調(diào)。接著研究基于分?jǐn)?shù)階傅里葉變換(FRFT)解調(diào)的Chirp單載波與多載波的調(diào)制系統(tǒng),以及利用去斜壓縮解調(diào)的Chirp掃頻-擴(kuò)頻系統(tǒng)。在上述系統(tǒng)理論仿真的基礎(chǔ)上,將各個(gè)通信系統(tǒng)的調(diào)制解調(diào)集成到設(shè)計(jì)的Matlab GUI界面上。最后對(duì)通信系統(tǒng)進(jìn)行加噪測(cè)試、水池多徑實(shí)驗(yàn)及海測(cè)實(shí)驗(yàn),驗(yàn)證本文所設(shè)計(jì)的通信系統(tǒng)的抗噪性能和抗多徑特性,實(shí)驗(yàn)結(jié)果表示,基于Chirp信號(hào)的擴(kuò)頻通信系統(tǒng)具有較好的抗噪和抗多徑性能。論文的主要工作如下： 1.系統(tǒng)地介紹國(guó)內(nèi)外Chirp擴(kuò)頻技術(shù)的發(fā)展現(xiàn)狀和研究概況。 2.并提出一種適用于水聲通信的幀同步結(jié)構(gòu),仿真測(cè)試在不同信道條件下的同步性能。 3.系統(tǒng)介紹Chirp擴(kuò)頻技術(shù),對(duì)Chirp單載波的高階調(diào)制技術(shù)進(jìn)行研究,接收端采用FRFT解調(diào),為抵抗多徑信道的頻率選擇性衰落,提出基于多載波技術(shù)的Chirp擴(kuò)頻調(diào)制技術(shù),對(duì)比分析Chirp單載波與多載波的系統(tǒng)性能。 4.針對(duì)水聲強(qiáng)多徑的特點(diǎn),研究一種抗多徑的Chirp掃頻-擴(kuò)頻系統(tǒng),分析不同信道參數(shù)對(duì)系統(tǒng)的影響,并提出了一種結(jié)合FRFT解調(diào)的MFSK-Chirp掃頻-擴(kuò)頻系統(tǒng),進(jìn)一步提高系統(tǒng)的傳輸速率。 5.在上述理論分析和仿真測(cè)試基礎(chǔ)上,將通信系統(tǒng)集成到Matlab GUI界面,進(jìn)行抗噪測(cè)試、水池多徑實(shí)驗(yàn)和海洋測(cè)試實(shí)驗(yàn),驗(yàn)證系統(tǒng)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.
【學(xué)位授予單位】：廈門大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN929.3

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