Telecommunication and Networking lesson 2

Telecommunication and Networking lesson 2

In the name of God; The most kindly merciful.

Hello everyone ! :) I am again here to tell about new news for my second lesson :)
This week our topic is about Data communication.

#1

What does mean Data communication ???

- Data communication means electronic transmission on digital area. Info can appear in ;

Examples

Computer, Radio station

Telephone handset, workstation

Radio waves, coaxial cable

Video, text

# 2
Type of signal
All this examples which I wrote above needs to signal to transfer data and there are two types of signal ;

Analogue signal appear with two feaures frequency(oftenness) and amplitude (violence).

Digital signal is tranmission of binary electrical (by 0 and 1). every digital signal needs to changed into Analogue signal for tranfer to PSTN line. there are two way two change them to each other :

• The process of changing ANALOGUE to DIGITAL signal = Modulation

• The process of changing DIGITAL to ANALOGUE signal = Demodulation

Also Hardware that used in computer to do this process =

• MoDem

Binary system

Bit (binary) are the smallet part in digital. they only has two statement, 0 and 1.

Data transmission mode

I draw this chart based on my understanding

Data transmission mode

For this two transmissions there must be two serial transmission mode;    Asynchronous = how long the transmitter leave(signal of the bits), examples;

• your computer use asynchronous serial communication with the keyboard and mouse
• The serial port is used to communicate with an external devices such as modems.we can think, asynchronous as a faster means of connecting, but less reliable when transmitting.

 Synchronous =   large group of data transmission. 

I hope this draft will help for understand clearly ;

#3 lets look at our last topic for lesson 2 

There are two types of duplex settings used for communications on an Ethernet network: half duplex and full duplex. The figure shows the two duplex settings available on modern network equipment. lets look at by picture to understand easily