【作者】 刘伟；

【导师】 黄瑞光；

【作者基本信息】 华中科技大学 ， 通信与信息系统， 2004， 硕士

【摘要】 现代通信系统是陆-海-空三维通信网,三维通信网的组成主要制约于水下通信。声波是当前实现水下通信唯一可选的有效手段。海上中继通信平台是三维通信网的重要组成部分,它包括无线通信子系统和水声通信子系统,是实现水上水下互联通信的中继。本文主要进行该平台中水声通信子系统中数字调制器的研究。本文首先介绍了水声通信基本原理、发展和当前取得的一些进展。然后从水声通信系统中影响系统设计的因素出发,阐述了本系统中实现的FSK和时延差编码通信体制的基本原理,并对两种通信体制信号特点和实现进行了详细分析,这些分析为水声通信数字调制器的设计提供了依据。接着,本文对数字调制器的设计进行了详细讨论并重点分析了调制电路的设计。简要介绍了常用信号合成技术,对采用的直接数字频率合成技术的原理和特点进行了详细分析,提出采用这种技术实现调制电路的方案,并在数字调制器的设计中采用了PC机和调制电路通过串口配合工作的结构。最后根据设计的数字调制器的结构和调制电路特点,划分了各模块功能,并对各部分功能进行软硬件实现,在调制电路的软件设计中采用了嵌入式操作系统μC/OS-II以支持软件开发。经过多次实验室测试,数字调制器工作正常能满足需要。对测试中系统存在的一些问题,提出了改进方向。更多还原

【Abstract】 Modern communication system is a land-sea-space three-dimensional communication network whose realization is mainly restrained by underwater communication. Acoustic is the only effective means available in underwater communication at present. The marine relaying communication platform that relay communication among under-water and above-water parts is an important component of it, which includes wireless communication subsystem and underwater acoustic communication subsystem. This paper mainly carries on the research of the digital modulator in underwater acoustic communication subsystem of this platform.This paper firstly introduces basic principles, development state and achievements of underwater acoustic communication. Then proceed from main factors that influence the system design, the paper explains the basic principles of FSK and Pattern Time-Delay Coding applied in our system and analyzes signal characteristics and realization of each method in detail. These discuss offers definite basis for the design of the digital modulator.Next, this paper discusses design of the digital modulator and especially analyzes design of modulating circuit. Common frequency synthetic technology is discussed briefly and basic principle and characteristic of direct digital frequency synthesize technology adopted in out design is investigated in detail. Then the scheme of modulating circuit is put forward, the structure that PC and the modulating circuit cooperate through serial connection is adopted, and module function is partitioned.Finally hardware and software are carried on to realize function of each module and embedded operate system μC/OS-II is utilized to support the software develop. Many laboratory-scale testing proves that the performance of the modulator has attained the design requirement and satisfied need of system. Moreover, to some questions existing while testing, some advices have been proposed.更多还原