Data Communication — NCERT Solutions

Data communication refers to the exchange of data between two or more networked or connected devices. The data may be text, image, audio, video, or multimedia.

The main components of data communication are:

1. Sender — the device that sends data.
2. Receiver — the device that receives data.
3. Message — the data or information being exchanged.
4. Communication medium — the path or link through which the message travels.
5. Protocols — the rules that must be followed for successful communication.

Full-duplex communication allows two-way communication in which both devices can send and receive simultaneously.

Among LAN, MAN, and WAN, a LAN generally has the highest speed because it covers a small area with less congestion. A WAN covers the largest area because it can span very large geographical regions.

The three categories of wired media are:

1. Twisted pair cable — It consists of two copper wires twisted together and insulated with plastic covers. The twisted configuration reduces electrical interference. It is inexpensive and commonly used in telephone lines and LANs.

2. Coaxial cable — It has a copper wire at the core, surrounded by insulating material and an outer conductor. It is better shielded than twisted pair and has more bandwidth. It is used to carry higher-frequency signals over longer distances.

3. Optical fibre cable — It carries data as light through a thin glass fibre. It is light in weight, has high bandwidth, allows long-distance transmission, and is not affected by electromagnetic noise. However, it is expensive and unidirectional.

Wired media use a physical cable or wire to carry data signals. Examples are twisted pair, coaxial cable, and optical fibre. Wired media are generally more reliable and less affected by interference.

Wireless media do not use a physical cable. Data travels through air as electromagnetic waves using antennas. Examples include radio waves, microwaves, infrared waves, Bluetooth, and Wi-Fi. Wireless media provide mobility and flexibility, but they are more prone to interference and signal loss.

So, the main difference is that wired media are physical and cable-based, while wireless media are air-based and cable-free.

Optical fibre cable carries signals in the form of light.

Advantages of optical fibre cable:

• It is light in weight.
• It has higher bandwidth, so the data transfer rate is higher.
• Signals can travel longer distances.
• It is not affected by electromagnetic noise or interference.

Disadvantages of optical fibre cable:

• It is expensive.
• It is unidirectional.
• Two cables are required for full-duplex communication.