hello geeks, In this article, we understand what is Transmission media and it’s classification, so let’s start. A transmission medium can be understood as easily as anything that can carry information from a source to a destination. For example, two people having a dinner conversation in the air, therefore here the air is a transmission medium. Mail carrier, a truck, or an airplane can be transmission medium for a written message.
In data communication, The transmission medium is usually free space (i.e. air), metallic cable, or fiber-optic cable and the definition of the information and the transmission medium is more specific. The information is usually a signal that is the result of a conversation of data from another form.
Classification of Transmission Media
Transmission media can be divided into two categories. Guided or unguided media. let’s simplified with this tree graph…
In this type of media, The signal energy travels within a solid media. The guided media is basically used for point to point communication. For example, of guided media are Twisted pair cable, Co-axial cable Fiber optic cable.
In the unguided media, the signal energy travels (propagates) in the form of unguided electromagnetic waves. For examples, unguided media are radio and infrared light.
These are Types of Guided Media
Twisted-pair cables are basically made of copper and a pair of wires are twisted together to reduce interference by adjacent wires. A twisted pair cable consists of two-conductor (normally copper), each with its own plastic insulation, twisted together. One of the wires is used to carry signals to the receiver, and the other is used only as a ground inference. The receiver uses the difference between the two. Telephone communication and for digital data transmission usually use twisted pair cable, over short distance upto 1km. Data transmission speeds of upto 9600 bits per second(bps) are possible for a distance upto 100 meters. Speed of data transmission is 1200 bps, for longer distance. [click here to read more…]
Co-axial cables consist of a central copper wire surrounded by a PVC insulation over which a sleeve of copper mesh is placed. In addition, The metal sleeve is again shielded by an outer shield of thick PVC material to reduce interference.
Most importantly, The construction of the co-axial cable gives it a good combination of high bandwidth and excellent noise immunity. For 1km cables, a data rate of 10mbps is feasible. [click here to read more…]
A fiber-optic cable is made of glass or plastic and transmits signals in the form of light signals. The construction of an optical fiber is as shown figure. It consists of an inner glass core surrounded by a glass cladding, that reflects the light back into the core. Each fiber is surrounded by a plastic jacket.
Most importantly, Fiber-optics, semiconductor lasers transmit information in the form of light along hair-thin glass (optical) fibers at the speed of light, (1,86,000 miles second) with no significant loss of intensity over very long distances. Basically, the fiber optics cables are made of tiny threads of glass or plastic. [click here to read more…]
It refers to the method of transmission of signals through the air/atmosphere. In this media, there is no cabling. The signal is broadcast in the air and thus are available to anyone, who has device cable of receiving them.
Basically, Unguided Media transports electromagnetic waves without using a physical conductor. For example, Here the part of the electromagnetic spectrum, ranging from 3kHz to 900 THz, used for wireless communication.
Unguided signals can be travel from the source to destination in several ways.
The three most important methods are:
- Ground Propagation ( below 2 MHz)
- Sky Propagation (2 to 30 MHz)
- Line-of-sight Propagation (above 30MHz).
The section of the electromagnetic spectrum defined as radio waves and microwaves is divided into eight ranges, call bands, each regulated by government authorities.
These bands are rated by very low frequency (VLF) to extremely high frequency (EHF).
These are the list of bands and their ranges with some applications.
|Very low frequency||3 – 30 kHz||Long-range radio navigation.|
|Low frequency||30 – 300 kHz||Radio beacons and navigation locators.|
|Middle frequency||300 kHz-3 MHz||
|High frequency||3 – 30 MHz||Citizen band, ship/aircraft communication|
|Very high frequency||30-300 MHz||
VHF TV, FM radio
|Ultra-high frequency||300-3 GHz||UHF TV, cellular phones, paging, satellite.|
|Super high frequency||3-30 GHz||Satellite communication|
|Extremely high frequency||30-300 GHz||Radar, satellite|
There are three types of wireless transmission or unguided media
These waves are very easy to generate and they can travel long distances. Due to these reasons, they are widely used for indoor and outdoor communication. These are the waves through which you walky-talky sets and radio operates. Most importantly, Radio waves have a frequency between 10kHz and 1GHz. [click here to read more…]
Electromagnetic waves having frequencies between 1 and 300GHz are called microwave. Microwave systems use very high-frequency radio or television signals to transmit data through space. However, at microwave frequencies, the electromagnetic waves cannot bend or pass through obstacles like hills, etc. [click here to read more…]
Above all, Infrared waves, with frequencies from 300GHz to 400THz(wavelength from 1-770mm), can be used for short-range communication. You must have used this communication while changing a channel of the TV while using the remote control or while transferring data from your mobile to your computer. Because these communications use infrared communication. [click here to read more..]
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