What is Transmission media?
- Transmission media is a communication channel that carries the information from the sender to the receiver. Data is transmitted through electromagnetic signals.
- The main functionality of the transmission media is to carry the information in the form of bits through LAN(Local Area Network).
- It is a physical path between transmitter and receiver in data communication.
- In a copper-based network, the bits in the form of electrical signals.
- In a fiber-based network, the bits in the form of light pulses.
- In OSI(Open System Interconnection) phase, transmission media supports Layer 1. Therefore, it is considered to be a Layer 1 component.
- The electrical signals can be sent through the copper wire, fiber optics, atmosphere, water, and vacuum.
- The characteristics and quality of data transmission are determined by the characteristics of medium and signal.
- Transmission media is of two types are wired media and wireless media. In wired media, medium characteristics are more important whereas, in wireless media, signal characteristics are more important.
- Different transmission media have different properties such as bandwidth, delay, cost, and ease of installation and maintenance.
- The transmission media is available in the lowest layer of the OSI reference model, i.e., Physical layer.
Some factors need to be considered for designing the transmission media:
- Bandwidth: All the factors are remaining constant, the greater the bandwidth of a medium, the higher the data transmission rate of a signal.
- Transmission impairment: When the received signal is not identical to the transmitted one due to the transmission impairment. The quality of the signals will get destroyed due to transmission impairment.
- Interference: An interference is defined as the process of disrupting a signal when it travels over a communication medium on the addition of some unwanted signal.
Causes Of Transmission Impairment:
- Attenuation: Attenuation means the loss of energy, i.e., the strength of the signal decreases with increasing the distance which causes the loss of energy.
- Distortion: Distortion occurs when there is a change in the shape of the signal. This type of distortion is examined from different signals having different frequencies. Each frequency component has its own propagation speed, so they reach at a different time which leads to the delay distortion.
- Noise: When data is traveled over a transmission medium, some unwanted signal is added to it which creates the noise.
We can group the communication media in two categories :
- Guided Media: It includes wires and cables
- Unguided Media: It includes waves through air, water, or vacuum.
Types of Guide Media
- Twisted Pair Cables: The most common form of wiring in the data communication application is the twisted pair cable.As a voice-grade medium (VGM), it is the basis for most internal office telephone wiring. It consists of two identical wires wrapped together in a double helix.
Different types and categories of twisted-pair cable exist ,but they are all the two things in common:
- the wires come in pairs
- the pairs of wires are twisted around each other.
Types of Twisted Pairs Cables
- Unshielded Twisted pair cables (UTP)
- Shielded Twisted Pair Cables (STP)
2. Coaxial Cables: This type of cable consisting of a solid wire core surrounded by one or more foil or wire shields, each separated by a kind of some kind of plastic insulator.
3.Optical Fiber: It consists of a thin strand of glass or glass-like material which are so constructed that they carry light from a source at one end of the fiber to a detector at the other end, The light source used are either light emitted diodes or laser diodes.