基阵式水下成像信号编码优化研究与实现

发布时间：2018-03-03 18:41

本文选题：水下声呐成像　切入点：信号优化　出处：《南京信息工程大学》2017年硕士论文　论文类型：学位论文

【摘要】：水下成像声呐技术被广泛用于海洋地貌勘探及内陆湖泊河流探索,该体制成像技术主要是基于基阵式的声学传感器工作的,但在实际应用中水下成像帧速率较低,实时性差,主要原因是传感器频率低、带宽窄而且基阵数量较多,所以采用发射阵列和接收阵列同时收发的成像方案。本文以系统的发射信号为研究目标,设计了两种正交性良好且利于通道分离的信号,克服了基阵阵元数量多、信号之间相关性差的问题,具有抗干扰性能强、带宽大的特点,而且实现简单,有利于水下成像分辨率的提高。最后通过硬件电路及上位机实现实际信号测试,成功对水下回波数据进行采集和接收。本文首先对脉冲压缩概念进行简单介绍,突出大时宽带宽积在信号性能中的重要作用,然后利用混沌天生良好的类随机性和对初值的敏感性,通过构造序列空间更广的复合混沌系统产生多组伪随机序列调制发射信号。仿真得出复合编码信号具有较好的自相关性和互相关性,并且可以从回波中有效的分离出信号进行成像,与传统信号优化方法相比,实现简单性能更好。本文还设计了一种基于m序列的跳频二相编码信号优化方法。跳频信号在通信领域具有抗干扰强、误码率低和抗多径效应的特点,符合水下声呐成像信号的设计要求,本文在水下成像频率允许范围内设计基于相关性能良好的m序列的跳频二相编码信号,此种复合信号的载频和相位能够在特定的范围内快速变换,兼具调频和调相的优点,又能弥补各自的不足,提高了信号在水下的正交性能和保密性。最后本文对水下成像系统基本构成进行介绍,详细阐述了系统各模块的功能与设计,并对该系统进行了实验验证。该系统主要由主控模块、功率放大模块、USB通信模块、收发电路模块构成,同时利用C++进行显控终端的设计,实现收发界面及与硬件的联通,通过回波数据的采集实现回波在界面的显示和通过USB进行数据与下位机的通信,成功实现了数据传输与保存等功能。
[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.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB56

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