Transmission Media in Computer Networks
In data communication,
- Transmission media is a pathway that carries the information from sender to receiver.
- We use different types of cables or waves to transmit data.
- Data is transmitted normally through electrical or electromagnetic signals.
Description
Transmission media are located below the physical layer. Computers use signals to represent data, which are transmitted in the form of electromagnetic energy.
Classification of Transmission Media
Twisted-Pair Cable
A twisted pair consists of two conductors, usually copper-based, with their own plastic insulation twisted together.
Twisted Pair Description
- One wire is used to carry signals to the receiver, while the second wire is used as a ground reference.
Advantages:
- Cheap
- Easy to work with
Disadvantages:
- Low data rate
- Short range
Twisted pair cables are commonly used in telephone networks, within buildings, and for local area networks (LAN).
Twisted Pair Cables
- Unshielded Twisted Pair (UTP)
- Shielded Twisted Pair (STP)
Unshielded Twisted Pair (UTP)
UTP consists of a pair of unshielded wires wound around each other. It is easy to install and is commonly used for telephone subscribers, DSL lines, and LANs with speeds of 10Mbps or 100Mbps.
Advantages of UTP:
- Affordable
- Most compatible cabling
Disadvantages of UTP:
- Susceptible to external electromagnetic interference
Shielded Twisted Pair (STP)
STP consists of a pair of wires wound around each other placed inside a protective foil wrap. It is used in IBM token ring networks and offers higher transmission rates over longer distances compared to UTP.
Advantages of STP:
- Shielded
- Faster than UTP
Disadvantages of STP:
- More expensive than UTP
- High attenuation rate
Coaxial Cable
Coaxial cable carries signals of higher frequency ranges than twisted pair cable. It consists of an inner conductor, which is a solid wire, and an outer conductor that serves as a shield against noise and as a second conductor.
Categories of Coaxial Cables
Coaxial cables are categorized by Radio Government (RG) ratings, which are de jure standards.
Coaxial Cable Connectors
- BNC Connectors (Bayone Neil Concelman)
Coaxial cables are used in various applications including television distribution, long-distance telephone transmission, short-distance computer systems links, and local area networks.
Fiber-Optic Cable
A fiber optic cable is made of glass or plastic and transmits signals in the form of light. Light travels in a straight line and changes direction when it goes from one substance to another.
Fiber Construction
Fiber-optic cables use connectors such as Subscriber Channel (SC) and Straight-Tip (ST) connectors.
Areas of application for fiber-optic cables include telecommunications, local area networks, cable TV, and CCTV.
Advantages of Fiber-Optic Cable:
- Greater capacity (e.g., data rates at 100 Gbps)
- Smaller size & lightweight
- Lower attenuation
Disadvantages of Fiber-Optic Cable:
- Installation and maintenance are expensive
- Only unidirectional light propagation
Unguided Media
Unguided media, such as wireless transmission waves, do not require physical cables. Examples include radio waves, microwaves, and infrared.
Radio Waves
Radio waves are used for short-range communication and can penetrate buildings easily. They are used in radio, television, and paging systems.
Microwaves
Microwaves are electromagnetic waves with frequencies between 1 GHz and 300 GHz. They are used for cellular phones, satellite networks, wireless LANs (Wi-Fi), WiMAX, and GPS.
Infrared
Infrared waves have frequencies between 300 GHz to 400 THz and are used for short-range communication, such as in night vision cameras, remote controls, and file sharing between devices.
Conclusion
Transmission media play a crucial role in computer networks, providing pathways for the transmission of data. Understanding the different types of transmission media and their characteristics is essential for designing and implementing effective communication systems.