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Working Principle of Optical Fiber Communication System

Views: 82     Author: Site Editor     Publish Time: 2020-04-09      Origin: Site

The principle of fiber optical communication is: at the sending end, the transmitted information (such as voice) must first be converted into an electrical signal, and then modulated onto the laser beam emitted by the laser, making the intensity of light change as the amplitude (frequency) of the electrical signal changes, and sent out through the optical fiber. At the receiving end, the detector converts it into an electrical signal after receiving the optical signal, and restores the original information after demodulation.



1. Work Principle

Send: The CPU serializes the parallel data through a dedicated IC chip, and inserts the corresponding bit code (start, stop, parity, etc.) according to the communication format. The output TXD sends the signal to the optical fiber connector (that is, the fixed plug). Then, the light source in the optical fiber connector performs electrical-optical conversion. The converted optical signal sends an optical signal to the fibre optical through the optical fiber moving plug, and the optical signal propagates forward in the optical fiber.


Receive: The optical signal from the optical fiber is sent to the receiver of the fixed plug through the moving plug of the optical fiber connector, and the receiver performs optical-electrical reduction of the received optical signal to obtain the corresponding electrical signal, which is sent to the RXD input end of the dedicated IC chip, and the serial data is changed to parallel data via the dedicated IC chip, and then transmitted to the CPU.



2. Application Field

The application field of optical fiber communication is very extensive, mainly used for local telephone trunks. The advantages of optical fiber communication can be fully exerted here, and it will gradually replace the cable and be widely used. It is also used for long-distance trunk line communication. In the past, it mainly relied on cable, microwave, and satellite communications. Now it is gradually using optical fiber communication and has formed a globally dominant bit transmission method. It is used in the global communication network and public telecommunications networks of various countries. It is also used for high-quality color television transmission, industrial production site monitoring and dispatching, traffic monitoring and control command, urban cable television network, and common antenna (CATV) system. It is used in optical fiber local area network and others such as in aircraft, spaceship, ship, power department, military, etc.


The optical fiber transmission system is mainly composed of: optical transmitter, optical receiver, optical cable transmission line, optical repeater and various passive optical devices. To achieve communication, the baseband signal must also be processed by the electrical terminal and sent to the optical fiber transmission system to complete the communication process.


It is suitable for fiber optical analog communication system, but also suitable for optical fiber digital communication system and data communication system. In the optical fiber analog communication system, electrical signal processing refers to processing such as amplification and pre-modulation of the baseband signal, and electrical signal inverse processing is the reverse process of originating processing, that is, demodulation, amplification and other processing. In the optical fiber digital communication system, electrical signal processing refers to amplifying, sampling, and quantizing the baseband signal, that is, pulse code modulation (PCM) and line code encoding processing, etc., and electrical signal inverse processing is also the inverse process of origination. For data optical fiber communication, electrical signal processing mainly includes amplifying the signal. Unlike digital communication systems, it does not require code conversion.