水流场的声学散射信号的模拟仿真

论文总字数：27370字

摘 要

声学多普勒流速剖面仪作为一种新型的利用声学多普勒原理测量水流剖面流速的测流装置^[1]，在水下导航定位系统中具有重要作用，在水文测量中有着广泛的应用。

四波束的水流测量完成了对水流层的平均流速的测量，并取得了良好的效果。对四波束的推广可以采用多波束的概念来获得整个流场的流速和散射强度分布特性的测量。四波束的算法和工程应用为多波束测量提供了依据。多波束测量结果将产生大量数据，因此需要较大的硬件和软件的投入。

本文基于声学多普勒测流原理，介绍了相关技术在国内外的发展现状，并在C语言环境下，建立了三维模拟流场。由发射阵元向水流场中发射一段7位barker码脉冲信号，然后由接收阵元接收到回波信号，再通过采样等过程，产生提供给计算机的声散射信号的模拟数据，为进一步得到整个空间的流速信息奠定基础。仿真中考虑了声信号的频率、传输距离、散射强度等因素，并通过了对水回波的仿真模型进行了验证。

关键词：声学多普勒，多波束，回波信号，C语言

ABSTRACT

Acoustic Doppler flow profiler is a new type of flow measuring device that uses the acoustic Doppler principle to measure the flow velocity of a water flow. It plays an important role in underwater navigation and positioning systems and widely used in hydrological measurement.

The four-beam water flow measurement completed the measurement of the average flow velocity of the water layer and achieved good results. The generalization of the four beams can use the concept of multi-beam to obtain the measurement of the flow velocity and scattering intensity distribution characteristics of the entire flow field. Four-beam algorithms and engineering applications provide the basis for multi-beam measurements. Multi-beam measurements will generate a large amount of data and therefore require a large amount of hardware and software investment to support.

Based on the principle of acoustic Doppler flow measurement, this paper introduces the development status of related technologies at home and abroad, and establishes a three-dimensional simulated flow field in C language environment. A 7-bit barker code pulse signal is transmitted from the transmitting array element to the water flow field, and then the echo signal is received by the receiving array element. Next, the simulation data of the acoustic scattering signal supplied to the computer is generated by sampling and the like, which lays a foundation for further obtaining the flow velocity information of the entire space. The frequency, transmission distance and scattering intensity of the acoustic signal are considered in the simulation, and the simulation model of the water echo is verified.

KEY WORDS: Acoustic Doppler, multiple beams, echo signal，C language

目 录

第一章 绪论 1

1.1研究背景及意义 1

1.2国内外研究现状 2

1.2.1国外研究现状 2

1.2.2国内研究现状 3

1.3研究内容 4

1.4论文组织架构 4

第二章 水下声学多普勒效应基础 6

2.1水声学的基本概念 6

2.1.1声波传播的速度 6

2.1.2声呐方程的基本参数 6

2.1.3传播损失 7

2.1.4指向性指数 8

2.1.5声波的散射 9

2.1.6混响和噪声 9

2.2多普勒测流的原理 9

2.2.1 多普勒效应 9

2.2.2 多普勒测流的公式 10

2.2.3 盲区和旁瓣 11

2.3本章小结 11

第三章 回波信号的仿真分析 12

3.1回波建模 12

3.2回波仿真 13

3.2.1发送信号的形式 13

3.2.2流程的回波仿真 13

3.3回波模型参数对测流的影响 14

3.4本章小结 14

第四章 系统的设计与实现 15

4.1 系统运行环境和开发工具 15

4.1.1运行环境 15

4.1.2开发工具 15

4.2 程序流程设计 16

4.2.1编译预处理 16

4.2.2数据结构定义 17

4.2.3主函数 17

4.2.4具体模块处理函数的实现 18

4.3 仿真数据的输出与验证 20

4.3.1仿真数据的输出 20

4.3.2仿真数据的验证 21

4.4 本章小结 23

第五章 总结和展望 24

参考文献 25

致 谢 27

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