Transportation media can be defined as the physical path to convey the information between sender and receiver.
In other words, the procedure of transmitting the data between two or more digital devices in analog-digital form.
In a computer network, we make an effort towards a couple of things in which an important function is to send data. For this, there is a necessity of media transmission. The main characteristics of the transmission media is to conduct the information in the form of bits through local area network. Various physical media can be used for the actual transmission. Each one has its own specifications in terms of bandwidth, delay, cost and ease of installation and maintenance. The property and quality of data transportation are decided by the features and quality of medium and signals.
TYPES OF TRANSMISSION MEDIA
- Guided media (wired)
- Unguided media (wireless)
1. Guided media
Guided media is known as wired media or bounded media. In this media data is transmitted through different types of cables or wires. It uses the actual path to transport the signals and provides direction to signals for transmitting. The speed of signal transmission in guided media is mostly faster.
Advantages of guided media
- It provides a high data transmission rate.
- It provides secure communication.
- It is generally used in short-distance data transportation or transmission.
Classification of guided media
- Power lines: Power lines deliver electrical power to houses, and electrical wiring within houses distributes the power to electrical outlets. Power lines have been used by electricity companies for low-rate communication such as remote metering for many years, as well as in the home to control devices.
- Twisted pair: Twisted pair is light weighted cable, the wires of twisted pair are twisted together in the form of a helical, like a DNA molecule. It consists of two insulated copper wires about 1mm thick. Its frequency lies in the range of 0-3.5kHz. Twisted pair is of two types- shielded twisted pair and unshielded twisted pair. The most general application of twisted pair is the telephone system.
- Coaxial cable: A coaxial cable consists of a stiff copper wire as the core, surrounded by an insulating material. The outer conductor is covered in a protective plastic sheath and the insulator is encased by a cylindrical conductor, often as a closely woven braided mesh. It has greater bandwidth than the twisted pair. It is generally used in analog transmission and cable television.
Coaxial cable is of two types
1. Baseband transmission: This transmission is referred to as the process of transmitting a single signal at high speed.
2. Broadband transmission: This transmission is referred to as the process of transmitting multiple signals simultaneously.
- Fiber optics: The telecommunication is vastly moving from copper wire networks to fiber optics. It is an ultra-thin string of glass that behaves like a waveguide for long distances. It is genuinely adjusted with two layers of glass- the core that holds the physical light signal and the cladding, i.e., a layer of glass covered the core.
An optical transmission system has three key components: the light source, transmission media, and detector. When light falls on the detector, it generates an electrical pulse. By attaching a light source to one end of an optical fiber and a detector to the other, we have a unidirectional data transmission system that accepts an electrical signal, converts and transmits it by light pulses, and then reconverts the output to an electrical signal at the receiving end.
2. Unguided media
Unguided media is also known as wireless or unbounded transmission media. Unguided media broadcasts the signals via air. The transmission speed of this media is commonly slower than guided media. There is no requirement for physical media for the transmission of electromagnetic signals.
Advantages of unguided media
- It broadcasts signals through the air.
- It is generally used in long-distance communication.
- It is less secure compared to guided media.
Types of unguided media
- Radio transmission
▫ It is easy to generate radio waves. They are widely used for communication both indoors and outdoors.
▫ Radio waves are omnidirectional which means they can travel in every direction from the source, so the transmitter and receiver do not have to be carefully aligned physically.
▫ The range of frequency is from 300GHz to 3KHz of radio waves. It is classified as terrestrial and satellite.
- Microwaves transmission
▫ It travels in straight lines. Due to this the transmitter and receiver stations will be exactly paralleled to each other. The frequency of microwaves lies between 1GHz to 300GHz.
▫ In addition, this directionality allows multiple transmitters lined up in a row to communicate with multiple receivers in a row without interference, provided some minimum spacing rules are observed.
▫ Microwaves are unidirectional, which means they travel in a single direction. It requires two antennas- A parabolic dish antenna and a horn antenna.
- Infrared transmission
▫ Infrared is generally used for short-range communication. It permits computing devices to connect via short-distance wireless signals.
▫ Infrared lights are produced from the heat and thermal radiation which is the electromagnetic form of radiation. It is relatively directional and easy to build but also have some drawbacks such as they cannot pass through solid objects.
▫ The frequency of infrared lies between 300GHz to 430THz.