What is data communication
(Qasim Imran Chaudhery, Lahore)
Data communication is the
transmission of electronic data over some media. The media may be cables,
microwaves.
Elements of Data Communication
Four basic elements are needed for any communication system.
1. Sender. The computer or device that is used for sending data is called
sender, source or transmitter. In modern digital communication system, the
source is usually a computer.
2. Medium. The means through which data is sent from one location to another is
called transmission medium. If the receiver and transmitter are within a
building, a wire connects them. If they are located at different locations, they
may be connected by telephone lines, fiber optics or microwaves.
3. Receiver. The device or computer that receives the data is called receiver.
The receiver can be a computer, printer or a fax machine.
4. Protocols. There are rules under which data transmission takes place between
sender and receiver. The data communication s/w are used to transfer data from
one computer to another. The s/w follows same communication protocols can
communicate and exchange data.
Data Transmission
Data may be transfer from one device to another by means of some communication
media. The electromagnetic or light waves that transfer data from one device to
another device in encoded form are called signals. Data transmissions across the
network can occur in two forms i.e.:
(i) Analog signal.
(ii) Digital signal.
Analog Signal. The transfer of data in the form of electrical signals or
continuous waves is called analog signal or analog data transmission. An analog
signal is measured in volts and its frequency is in hertz (Hz).
Advantages of Analog Signaling
Allows multiple transmissions across the cable.
Suffers less from attenuation.
Disadvantages of Analog Signaling
Suffers from EMI.
Can only be transmitted in one direction without sophisticated equipment.
Digital Signal
The transfer of data in the form of digit is called digital signal or digital
data transmission. Digital signals consist of binary digits 0 & 1. Electrical
pulses are used to represent binary digits. Data transmission between computers
is in the form of digital signals.