The study on transmission characteristics of Digital Optical fiber Communication System
This paper introduces a digital optical fiber communication systems transmission principle, and using MATLAB Simulink simulation module design a digital communication system simulation model. This simulation model of choice pulse modulation amplitude modulation, In the receiver using a cutoff frequency of 3500 Hz low-pass filter. In the receiver using a 3 ~ 5 times the power amplifier. Testing the communication system in different forms of modulation, different channels, for different input frequency, Communication System waveform recovery, and error rates. To experiment known to be high-quality digital fiber communication system, Need as much distinctly different length decreases as possible；In selecting channel coding manner possible to the election there were some redundant channel encoding. Win some experiments with the Nanjing - jiehui JH5002 fiber-optic communications system for experimental simulation results verified.
Key Words: PCM coder; CMI encryption; Modulation; BER; SNR
数字光纤通信系统传输特性的研究
本文主要介绍了数字光纤语音通信系统的传输原理，用MATLAB的simulink仿真模块设计了一个数字通信系统仿真模型。此仿真模型的调制方式选择脉冲振幅调制方式，在接收端采用一个截止频率为3500Hz的低通滤波器,在接收端采用一个3～5倍的功率放大器。测试了通信系统在不同的调制形式下、不同的信道中、对于不同的输入频率，通信系统波形的恢复情况以及误码率的情况。通过实验可知要想得到高质量的数字光纤通信系统，需要尽可能的使码子长度减小；在选择信道编码方式时要尽可能的选择有一定信道冗余的编码方式。实验部分选用运南京捷辉的JH5002光纤通信实验系统对仿真结果进行验证。
关键词：PCM编译码；CMI编译码 ；调制；误码率；信噪比413
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