Data Transmission Media in Computer Networks

In this article, we will discuss What is transmission media in computer networks and also discuss transmission medium types: wired media and wireless media.

What is Transmission media?

Transmission media is a communication channel means it is a medium for data transmission. In other words, when two devices want to communicate, at that time the communication channel they used is called transmission media.

Transmission Medium is used to carry data from the transmitter to the receiver. It is a physical path between sending machine and receiving machine in data communication means it provides a pathway over which the data can travel from sender-to-receiver.

Transmission Medium is a medium that is used to transfer the data from one place to another place. When we talk about transfer the data that’s not only mean internet data, we talk about all types of data, which can be radio network, TV network, phone network, local network, internet, etc.

Each of the messages can be sent in the form of data by converting them into binary digits. These binary digits are then encoded into a signal that can be transmitted over the appropriate medium.

In data communication, it works like a physical route between the sender and receiver. For example, a copper cable network uses bits as electrical signals while bits in a fiber network are available as light pulses.

 

 

Types of Transmission Media

1. Wired or Guided Media or Bound Transmission Media

  • Twisted Pair Cable
  • Coaxial Cable
  • Fiber Optic Cable

2. Wireless or Unguided Media or Unbound Transmission Media

  • Radio Waves
  • Microwaves
  • Infrared Waves

Types of Transmission Media

 

Wired or Guided Media or Bound Transmission Media

Guided transmission media are cables that are tangible or have a physical existence.

Wired transmission media use cable or wires for sending the data from one place to another. Cables can be twisted pair cables, coaxial cables or fiber optic cables.

It is also referred to as guided transmission media because the data guide goes through cables from one place to another.

It is also known as bounded transmission media because the data signals are bound by the cabling system.

Bounded transmission refers to the connectivity between a source and a destination using cables or wires. The signals have to travel through this channel i.e. physical medium.

 

Twisted Pair Cable

Twisted-pair cabling is the most popular network cable for data transmission.

It is lightweight, easy to install, inexpensive, and supports data speeds up to 100 Mbps.

It is a pair of copper wires. Copper wires are the most common and widely used wire for transmitting signals due to good performance at low cost.

A twisted pair cable consists of two conductors (normally copper), each pair of cable twisted together to form a single media with its own plastic insulation.

Out of these two wires, one wire carries the actual signal and the other is used for ground reference.

To identify each cable, these cables are color coated.

A twist between wires is helpful in reducing noise (electromagnetic interference) and crosstalk.

This type of cable is mostly used to provide voice and data transmission in telephone networks.

Shielded and Unshielded Twisted Pair Cable

 

The two types of twisted pair cables are:

  • Unshielded twisted pair (UTP)
  • Shielded twisted pair (STP)

Unshielded twisted pair (UTP)

  • There is no shield in unshielded twisted pair means no metal foil in UTP.
  • UTP cable is more common than STP cables because it’s costs less than STP and easily available due to its many use.
  • Due to its low cost, UTP cabling is widely used for local-area networks (LANs) and telephone connections because of its low cost.
  • Unshielded twisted-pair cables do not provide high bandwidth or good protection from interference like coaxial or fiber optic cables, but UTP cables are low cost and easier to work with.

Shielded twisted pair (STP)

  • These types of cable have a metal foil covering each pair of insulator conductors.
  • Shielding in STP cable helps to prevent electromagnetic noise and also eliminates crosstalk. The Data transmission rate is higher in STP.
  • Because of metal foil covering, these cables are more expensive than coaxial and unshielded twisted pair.

 

Coaxial Cable

Coaxial cable has two wires of copper.

The core/inner copper wire in the center and is made of the solid conductor which is used actual data transmission. It is enclosed in an insulating sheath.

The second/external copper wire is wrapped around and used to protect against external electromagnetic interference (noise).

This all is covered by plastic cover used to protect the inner layers from physical damage such as fire or water.

Coaxial Cable

Coaxial cables are categorized by their Radio Government (RG) ratings. Each RG number denotes a unique set of physical specifications

Common coaxial cable standards:

  • 50-Ohm RG-7 or RG-11: Used for thick Ethernet or “thicknet”.
  • 50-Ohm RG-58: Used for thin Ethernet, or “cheapernet”.
  • 75-Ohm RG-59: Used for cable television.
  • 93-Ohm RG-62: Used for ARCNET.

Fiber Optic Cable

A fiber optic cable is made of high quality of thin glass or plastic and is used to transfer digital data signals in the form of light over thousands of miles.

Fiber optic cables are not affected by electromagnetic interference, so noise and distortion are much less.

Fiber optic cables provide high data transmission and designed for long-distance.

Fiber optic cables transmit data signals using light pulses generated by small lasers or light-emitting diodes (LEDs).

The cable consists of one or more strands of glass, each slightly thicker than a human hair.

The center of each strand is called the core, which provides a pathway for light to travel.

The core is surrounded by a layer of glass known as cladding that reflects light inward to avoid loss of signal and allow the light to pass through bends in the cable. Because of this reflective cladding, no light can escape the glass core.

Most of the world’s Internet use fiber optic cables because it provides higher bandwidth and transmits data over longer distances.

Fiber Optic Cable

 

you can read this article: What are network topologies and its types?

 

Wireless or Unguided Media or Unbound Transmission Media

Wireless Transmission Media does not establish a physical link between two or more devices, it helps to communicate wirelessly.

Data transmits through electromagnetic waves without using any physical medium. Hence it is known as wireless transmission.

Wireless signals are transmitted over the air and are received and interpreted by suitable antennas. Air is the medium through which electromagnetic energy can flow easily.

When an antenna is attached to the electrical circuit of a computer or wireless device, it converts digital data into a wireless signal and spreads all over its frequency range. The receptor at the other end receives these signals and converts them back into digital data.

It is also referred to as unguided transmission media because data do not guide through cables, data transmit wirelessly through the air unguided.

The main features of wireless media are less secure, the signal can be transmitted through the air, and can be applied for larger distances.

What are Electromagnetic Waves?

According to economictimes.indiatimes.com

Electromagnetic waves are formed when an electric field comes in contact with a magnetic field. Hence they are known as ‘electromagnetic’ waves.

The electric field and magnetic field of an electromagnetic wave are perpendiculars (at right angles) to each other.

EM waves travel with a constant velocity of 3.00 x 108 ms-1 in vacuum. They are deflected neither by the electric field nor by the magnetic field.

An electromagnetic wave can travel through anything – be it air, a solid material, or vacuum. It does not need a medium to propagate or travel from one place to another. Mechanical waves (like sound waves or water waves), on the other hand, need a medium to travel.

 

Radio Waves

Radio waves are electromagnetic waves (EM waves) which are the longest wavelengths in the electromagnetic spectrum.

Its wavelengths can be between 1 millimeter and 10,000 kilometers and in frequencies can as high as 300 GHz to as low as 30 Hz.

If the wavelength is 1mm, the corresponding frequency 300 GHz, and if the wavelength is 10,000 km, the corresponding frequency 30 Hz.

The radio frequency is easy to generate because it has a large wavelength and can travel long distances.

Transmitters are used to generate radio waves artificially which are received by radio receivers using antennas.

Radio stations transmit radio signals using transmitters, and these signals are received by receivers installed in our devices. In simple words, transmitters transmit radio signals and receivers capture those radio signals using antennas which installed in our devices.

Radio waves are omnidirectional means they travel in all directions from the source. So when a sending antenna sends radio signals, it can be received by any receiving antenna.

 

Microwaves

Microwave is a type of radio wave that has high frequencies. It can be classified as a subclass of radio waves.

The frequencies range of microwaves is between from 300 MHz to 300 GHz.

Microwave is the subpart of radio waves, means it’s a high frequency of radio waves.

When the frequency exceeds 100 MHz, EM waves travel in a straight line so the signals can be sent by beaming those waves towards one particular station.

Microwaves are unidirectional because it has a higher frequency and travels in straight lines.

For sending signals to another antenna, both sender and receiver antennas should be mounted on the towers and must be aligned to be strictly in line-of-sight.

It is used for satellite communications, navigation, radar, remote sensing, and other short-range communications systems.

 

Infrared Waves

Infrared waves are also a part of wireless transmission.

These waves are used for very short-range communication because its frequency range is very high from 300 GHz to 400 THz that cannot travel in the longer distances.

Infrared waves are mostly used very short distance communication like TV remote, wireless mouse, wireless printer, automatic doors, handheld devices, etc.

Because if very high frequency, these waves cannot penetrate walls.

Its short-range communication does not affect two communication devices in one room to the next room. That’s the reason when we are using an infrared TV remote in one room than the infrared signals do not interfere with in the next room infrared TV remote control.

The data transfer rate is very high because it has a very high frequency.

 


Frequently Asked Question about Transmission Media

What are the other names of wired media transmission?

Wired media transmission can also be called guided media or bounded media.

Why is wired media called guided media?

Because using wired media, we can guide the data signals using wires from one location to another, so that way it can also be called guided media.

Why twisted pair cables are twisted with each other?

They are twisted because this twist between the wires is helpful to reduce the electromagnet interference, which helps to reduce the noise.

Which type of cable mostly used in telephone networks?

Twisted pair cables are mostly used in telephone networks.

How many types of twisted pair cable?

There are only two types of twisted-pair cables.
Unshielded twisted pair (UTP), which has no shield means there is no metal foil.
Shielded twisted pair (STP), which covered with a metal foil for preventing electromagnetic noise.

Which cable type is best for highest data transmission?

Fiber Optic Cable is the only cable, which provides the highest data transmission in the form of light. These types of cables are designed for long-distance and also no affected by any electromagnetic interference.

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