What is Data Communications?
Data communication is a process of transferring data electronically from one place to another. Data can be transferred by using different medium. The basic components of data communications are as follows:
- Message
- Sender
- Receiver
- Medium/ communication channel
- Encoder and decoder
Message
The message is the data or information to be communicated. It may consist of text, number, pictures, sound, video or any a combination of these.
Sender
Sender is a device that sends message. The message can consist of text, numbers, pictures etc. it is also called source or transmitter. Normally, computer is used as sender in information communication systems.
Receiver
Receiver is a device that receives message. It is also called sink. The receiver can be computer, printer or another computer related device. The receiver must be capable of accepting the message.
Medium
Medium is the physical path that connects sender and receiver. It is used to transmit data. The medium can be a copper wire, a fiber optic cable, microwaves etc. it is also called communication channel.
Encoder and decoder
The encoder is a device that converts digital signals in a form that can pass through a transmission medium. The decoder is a device that converts the encoded signals into digital form. The receiver can understand the digital form of message. Sender and receiver cannot communicate successfully without encoder and decoder.
What is signal?
Signal is an electromagnetic or light wave that represents data. Signals are used to transfer data from one device to another through a communication medium.
Types of Signals
Different forms of communication signals are as follows:
- Digital signals
- Analog signals
Digital Signals
Digital signal is a sequence of voltage represented in binary form. The digital signals are in the form of electrical pulses of ON and OFF. These signals are in discrete form. Digital signals are faster and efficient. They provide low error rates. They also provide high transmission speed and high-quality voice transmission.
All data communication between the computers is in digital form. Computers understand and work only in digital form. The following figure represents a high voltage as a 1 and a low voltage as a 0.
Analog Signals
Analog signal is a continuous electrical signal in the form of wave. The wave is known as carrier wave. Telephone line is most commonly used media for analog signals.
Characteristics of Analog Signals
Two characteristics of an analog wave are as follows:
- Frequency: the number of times a wave repeats during a specific time interval is known as frequency.
- Amplitude: the height of wave within a given period of time is known as amplitude.
