制作者Communication-System(通信系统)

2021年1月27日发(作者：oda是什么意思)
Communication System


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Abstract
】

Communication industry is one of the oldest industry. In the new technology
revolution, driven by information highway construction wave, communication technology has
been developing rapidly.
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Key Words
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communication system; composition; model; classification; development trend

1.1 Composition of Communication System

From ancient to modern times, human social activities always can not leave news
transmission and ancient of the news tree, beacon-fire tower and modern social text,
letters, telegraph, telephone, radio, television, remote control, remote sensing etc, these are the
means of information can use language, words, data, or images of different
forms to express these languages, text, data, or image themselves are not
information but news.


Therefore, the basic purpose of communication is to transmit the useful information.

Based on this understanding,
transmission
1.2 General Model of Communication System

of Information
The source of information is the generation of effect is to convert all the news to the
original electrical signals, called news signal or baseband kinds of digital terminal
equipment for example, telephone, television camera, the telex machine, computer is the
former are analog source and the output is analog latter is digital source and
the output is the discrete digital signal.

Equipment
The basic function of send equipment is matching up the source and channel. Communication
means is tion is the most common way of digital communication
system,send equipment can be divided into the source coding and channel coding.

ation Channel
Channel refers to the physical media of the transmission signal.
In a wireless channel,it can
be atmosphere (free space). In the cable channel, it can be cable or optical and wireless
channel all have a variety of physical inherent characteristics of the medium and the
interference directly related to the quality of the ing to the difference of the
study, it need to set up different mathematical model of the actual physical as to reflect
on the influence of the signal transmission medium.
4.
Source of Noise
Noise is not the thing that human want to add,but channel of communication system
inherent source of the noise is can be divided into the interior noise and external
noise. The external noise often introduces from the channel.
e Device
The basic function of the receiving device is complete inverse transform of sending
is demodulating, decoding, decoding, etc.
ationsink
Informationsink is home to the information that will be transformed. It can convert the
original signal into the news.
1.3 Classification of Communication System

ing to communication business classification

According to communication business, communication system classify telephone
communication and other one service is indispensable in the
telecommunication field. It belongs to the communication between recent years, with
the rapid development of telephone communication, the telephone communication include data
service, computer communication, database retrieval, E-mail, electronic data exchange,visual
graphic and meeting TV, image communication, phone communication is the most
developed. So other communication ofen draw support from public phone communication
addition, there are control communications business for example remote measure,
remote control.

ing to Modulation Method Classification

According to

modulation method ,communication system can be divided into baseband
transmission and frequency nd transmission will be transmitted directly
without modulation signal, such as audio local ncy transmission is the floorboard of the
transmission of signal that had modulated.

3. According to Signal Features Classification


According to the transmission of channel is analog signal or digital signal, the
communication system can classify analog communication system and digital communication
system.

4. According to The Transmission Medium Classification

According to the transmission medium,communication system can be divided into wire
communication system and wireless communication communication uses lead as
transmission medium to finish communication, such as the telephone, cable TV, submarine cable
ss communication depends on electromagnetic wave propagation in space
to achieve the purpose of sending messages, such as short wave ionosphere spread, microwave
spread.

5. According to Workband Classification

According to the working frequency of communication equipment ,communication can be
divided into long wave communication, medium wave communication, short wave
communication, far infrared communication, etc.
6. According to Signal Multiplex Method Classification


Transmission multiple signal have three multiplex method, namely frequency division
multiplex, time division multiplex and code division ncy division multiplex uses
the method of spectrum moved to occupy different frequency of different division
multiplex uses the method of modulation by using a pulse signal to occupy different time
division multiplex uses orthogonal pulse sequences carried different signals.

Traditional analog communication uses frequency division the development
of digital communication, time division multiplex communication system applys more and more
extensively. Code division multiplex mainly used in the spread spectrum communication of the
space communication.

1.4 Development Trend of Communication System