摘要（船用）自动识别系统（AIS），是用于船与船之间、船舶与岸上基站之间相互通信交流的系统，可以便于海事管理。运用AIS蜂窝通信的原理，海上船只能够及时与其他船只进行通讯；而岸上的基站（一般为港口）能实时掌握各船舶的航行状况并依此发出调度信息。但船用AIS系统存在缺陷：一、通信距离受约束，只可与近岸的船舶进行通讯；二、船舶数量增加，海上情况愈加复杂。因而必须引进拥有更大通信与观测范围的星载AIS系统，以应对挑战。42461
本文设计了一种全数字的星载AIS接收机，给出了数字接收机系统框图和各组成模块的算法设计。接收到的射频信号首先通过数字下变频算法变频到基带，信道分离算法将AIS两路信道分离；为了解调时预先确定帧头位置和载波频率偏移，设计了符号定时同步算法和帧头精确估计算法以满足后续解调的需求；重点研究了接收机解调部分，给出了差分解调和Viterbi解调的算法流程和仿真结果，进行了性能评估和参数选择。
关键词 星载AIS 高斯最小频移键控 数字接收机 定时同步 Viterbi解调
毕业论文设计说明书外文摘要
Title Research on Demodulation Algorithm for Space-Borne AIS receiver
Abstract
(Marine) Automatic Identification System, (AIS), traditionally is a kind of communication system used between ship and ship, ship and shore base station. Using the principle of AIS cellular communication, ships can promptly carries on the communication with other vessels and shore base station (regularly port) can real-time control the sailing conditions of ship and accordingly issue scheduling information, which can be achieved on AIS.
This paper designs a full digital satellite AIS receiver, and shows the digital receiver system block diagram and the algorithm design of each module. The received RF signal first goes through the digital frequency conversion algorithm to baseband, and then channel separation algorithm separates the two AIS channels; Before demodulation, frame head position and carrier frequency offset is needed, and symbol timing synchronization algorithm and accurate estimation of frame head algorithm will meet the accuracy requirements; In the design of receiver, demodulation algorithm is the focus of this topic. After giving simulation of the differential decomposition algorithm and Viterbi demodulation, the demodulation algorithm finally chosen is most suitable for the design of the receiver. At last, it performs evaluation and makes a choice on various parameters.
Keywords Space AIS, GMSK modulation, Digital Receiver, Timing Synchronization , Viterbi Demodulation
目 次
1. 引言 1
1.1 研究背景 1
1.2 研究现状 1
1.3 本文工作和章节安排 2
2. 星载AIS介绍 4
2.1 星载AIS全局架构 4
2.2 船载AIS发射机 4
2.3 星载AIS数字接收机 9
2.4 本章小结 11
3. 星载AIS全数字解调研究 12
3.1 星载AIS数字接收机全局架构 12
3.2 基带信号处理 13
3.3 解调算法研究 23 星载AIS接收机解调算法研究:http://www.751com.cn/tongxin/lunwen_42928.html