本文選題：水下聲吶成像　切入點(diǎn)：信號優(yōu)化　出處：《南京信息工程大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：水下成像聲吶技術(shù)被廣泛用于海洋地貌勘探及內(nèi)陸湖泊河流探索,該體制成像技術(shù)主要是基于基陣式的聲學(xué)傳感器工作的,但在實(shí)際應(yīng)用中水下成像幀速率較低,實(shí)時性差,主要原因是傳感器頻率低、帶寬窄而且基陣數(shù)量較多,所以采用發(fā)射陣列和接收陣列同時收發(fā)的成像方案。本文以系統(tǒng)的發(fā)射信號為研究目標(biāo),設(shè)計了兩種正交性良好且利于通道分離的信號,克服了基陣陣元數(shù)量多、信號之間相關(guān)性差的問題,具有抗干擾性能強(qiáng)、帶寬大的特點(diǎn),而且實(shí)現(xiàn)簡單,有利于水下成像分辨率的提高。最后通過硬件電路及上位機(jī)實(shí)現(xiàn)實(shí)際信號測試,成功對水下回波數(shù)據(jù)進(jìn)行采集和接收。本文首先對脈沖壓縮概念進(jìn)行簡單介紹,突出大時寬帶寬積在信號性能中的重要作用,然后利用混沌天生良好的類隨機(jī)性和對初值的敏感性,通過構(gòu)造序列空間更廣的復(fù)合混沌系統(tǒng)產(chǎn)生多組偽隨機(jī)序列調(diào)制發(fā)射信號。仿真得出復(fù)合編碼信號具有較好的自相關(guān)性和互相關(guān)性,并且可以從回波中有效的分離出信號進(jìn)行成像,與傳統(tǒng)信號優(yōu)化方法相比,實(shí)現(xiàn)簡單性能更好。本文還設(shè)計了一種基于m序列的跳頻二相編碼信號優(yōu)化方法。跳頻信號在通信領(lǐng)域具有抗干擾強(qiáng)、誤碼率低和抗多徑效應(yīng)的特點(diǎn),符合水下聲吶成像信號的設(shè)計要求,本文在水下成像頻率允許范圍內(nèi)設(shè)計基于相關(guān)性能良好的m序列的跳頻二相編碼信號,此種復(fù)合信號的載頻和相位能夠在特定的范圍內(nèi)快速變換,兼具調(diào)頻和調(diào)相的優(yōu)點(diǎn),又能彌補(bǔ)各自的不足,提高了信號在水下的正交性能和保密性。最后本文對水下成像系統(tǒng)基本構(gòu)成進(jìn)行介紹,詳細(xì)闡述了系統(tǒng)各模塊的功能與設(shè)計,并對該系統(tǒng)進(jìn)行了實(shí)驗驗證。該系統(tǒng)主要由主控模塊、功率放大模塊、USB通信模塊、收發(fā)電路模塊構(gòu)成,同時利用C++進(jìn)行顯控終端的設(shè)計,實(shí)現(xiàn)收發(fā)界面及與硬件的聯(lián)通,通過回波數(shù)據(jù)的采集實(shí)現(xiàn)回波在界面的顯示和通過USB進(jìn)行數(shù)據(jù)與下位機(jī)的通信,成功實(shí)現(xiàn)了數(shù)據(jù)傳輸與保存等功能。
[Abstract]:Underwater imaging sonar technology is widely used in marine geomorphology exploration and inland lake river exploration. The system imaging technology is mainly based on acoustic sensors of matrix, but in practical application underwater imaging frame rate is low and real-time is poor. The main reason is that the frequency of sensor is low, the band is narrow and the number of array is large, so the imaging scheme of transmitting array and receiving array is adopted. Two kinds of signals with good orthogonality and good channel separation are designed, which overcome the problems of large number of matrix elements and poor correlation between signals, have the characteristics of strong anti-jamming performance, large bandwidth, and simple implementation. It is beneficial to improve the resolution of underwater imaging. Finally, the actual signal testing is realized by hardware circuit and upper computer, and the underwater echo data is collected and received successfully. Firstly, the concept of pulse compression is introduced briefly in this paper. The importance of wideband wide product in signal performance is highlighted, and then chaos is used to make use of its inherent randomness and sensitivity to initial values. By constructing a complex chaotic system with a wider sequence space, multiple sets of pseudorandom sequence modulated transmission signals are generated, and the simulation results show that the composite coded signals have good autocorrelation and mutual correlation. And can be effectively separated from the echo signal for imaging, compared with the traditional signal optimization method, This paper also designs an optimization method of frequency hopping binary coding signal based on m sequence. Frequency hopping signal has the characteristics of strong anti-jamming, low bit error rate and anti-multipath effect in the field of communication. According to the design requirements of underwater sonar imaging signal, the frequency hopping binary coded signal based on m sequence with good correlation performance is designed within the allowable frequency of underwater imaging. The carrier frequency and phase of the composite signal can be rapidly converted in a specific range, which has the advantages of frequency modulation and phase modulation, and can make up for their respective shortcomings. The orthogonal performance and confidentiality of the signal under water are improved. Finally, the basic structure of underwater imaging system is introduced, and the function and design of each module of the system are described in detail. The system is mainly composed of main control module, power amplifier module, USB communication module and transceiver circuit module. At the same time, the display and control terminal is designed with C to realize the transceiver interface and the connection with hardware. The functions of data transmission and storage are successfully realized through the acquisition of echo data, the display of echo at the interface and the communication between the data and the lower computer through USB.
【學(xué)位授予單位】：南京信息工程大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB56

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