What is bandwidth in transmission media?

What is meant by the bandwidth of a signal? Bandwidth is a range of frequencies within a continuous set of frequencies. It is measured in Hertz. The purpose of a communication system is to transfer information from the transmitter which is located in one place to a receiver which is usually far away from the transmitter. When we send an email, we are sending it as bits of information to the receiver. This information is transported over the air or wire at a certain frequency depending on the mode chosen. Another factor at play is that the information can be in many forms; voice, video, photo, word document, etc. Luckily there is a very large spectrum of frequencies waiting for our bidding.

The smaller frequencies are used for long-distance communication and can travel unaffected over large distances, ie, less attenuation. Larger frequencies have greater energy and can carry more information but they are very inefficient and cannot be transmitted over long distances. One such set of frequencies are used for a very different purpose than others, ie the microwaves. For transmitting sounds or speech, the frequency range of 300 Hz to 3100 Hz is sufficient and hence the current telephones operate at a bandwidth of 2800 Hz. Transmission of music requires a bandwidth of the signal of 20 kHz because of the various instruments with a variety of pitches.

The audible range of a human is from 20 Hz to 20 kHz whereas a dog can hear from 50 Hz to 46 kHz. The key characteristic of bandwidth is that any band of a given width can carry the same amount of information, regardless of where the band is located in the frequency spectrum. For example, a 4kHz signal bandwidth can transmit a telephone conversation whether it is through lower frequency, like a wired telephone or modulated to a higher frequency, ie cell phone.

What we discussed till now was with respect to analog signals. Digital signals are in rectangular form, either on or off, ie 1 or 0. The sine wave is the fundamental waveform and every other kind of waveform (triangular, rectangular as in digital) can be written as a combination of the fundamental sine wave. We get digital pulses when we superimpose sine waves of different harmonics.

Learn more about Difference Between Analog And Digital Signal.

Bandwidth of Transmission Medium

There are various methods of transmission, yes lots of them. From smoke signals and beating drums to the current fiber optics. The amount of data these various methods can transfer differ hugely. During the 1990’s and the early 2000’s, India had dial-up internet which was really slow but now with infrastructure changes we have faster internet. Wires are the most commonly used transmission media. A wire offers a bandwidth of approximately 750 MHz. The transmission over the air and free space range from a few hundred kHz to a few GHz. An optical fiber can offer a signal bandwidth of over 100 GHz. The bandwidths are allocated to radios, televisions and cellular communication companies by the government of the country.

Measurement of the Bandwidth of a Signal

Bandwidth is a key concept in several technological fields. In signal processing, it describes the difference between upper and lower frequencies in transmission signals like radio signals, etc. The measurement of the bandwidth of a signal is done in hertz (Hz). Depending on the context, the bandwidth may specifically be referred to passband bandwidth or base bandwidth.

A signal processing system works efficiently over a finite range of frequencies. Within this band of frequencies, the response of a system is flat. Outside this band, the frequency response gradually drops off. The boundary in a system’s frequency response at which the energy flowing through a system reduces rather than passing through is known as the cutoff frequency. A passband bandwidth is a difference between the upper and lower cut off frequency and a baseband bandwidth equals the highest frequency of a system. Bandwidth in hertz is a central concept in many fields like electronics, radio communications, digital communications, information theory, etc.

The representation of data can be done through computers as well as other types of telecommunication devices with the help of signals. These are broadcasted from one device to another in the shape of electromagnetic energy. The signals like electromagnetic can travel throughout vacuum, air otherwise other transmission mediums to travel from one sender to another receiver. Electromagnetic energy mainly includes voice, power, radio waves, visible light, UV light, & gamma rays. In the OSI model, the first layer is the physical layer which is dedicated to the transmission media. In data communication, a transmission media is a physical lane between the Tx & the Rx and it is the channel where data can be transmitted from one area to another.

What is Transmission Media?

Definition: A communication channel that is used to carry the data from the transmitter to the receiver through the electromagnetic signals. The main function of this is to carry the data in the bits form through the Local Area Network (LAN). In data communication, it works like a physical path between the sender & the receiver. For instance, in a copper cable network the bits in the form of electrical signals whereas in a fiber network, the bits are available in the form of light pulses. The quality, as well as characteristics of data transmission, can be determined from the characteristics of medium & signal. The properties of different transmission media are delay, bandwidth, maintenance, cost, and easy installation.

Different Types of Transmission Media

Transmission media is classified into two types namely wired media & wireless media. The medium characteristics of wired media are more significant but, in wireless media the signal characteristics are important.

Guided Media

This kind of transmission media is also known as wired otherwise bounded media. In this type, the signals can be transmitted directly & restricted in a thin path through physical links.

The main features of guided media mainly include secure, high-speed, and used in small distances. This kind of media is classified into three types which are discussed below.

 Twisted Pair Cable

It includes two separately protected conductor wires. Normally, some pairs of cables are packaged jointly in a protective cover. This is the most frequently used type of transmission media and it is available in two types.

  UTP (Unshielded Twisted Pair)

This UTP cable has the capacity to block interference. It doesn’t depend on a physical guard and used in telephonic applications. The advantage of UTP is a low cost, very simple to install, and high speed. The disadvantages of UTP is liable to exterior interference, transmits in fewer distances, and less capacity.

  STP (Shielded Twisted Pair)

STP cable includes a particular jacket for blocking outside interference. It is used in rapid data rate Ethernet, in voice & data channels of telephone lines.

The main advantages of STP cable mainly include good speed, removes crosstalk. The main disadvantages are hard to manufacture as well as install, It is expensive and bulky also

  Coaxial Cable

This cable contains an external plastic cover and it includes two parallel conductors where each conductor includes a separate protection cover. This cable is used to transmit data in two modes like baseband mode as well as broadband mode. This cable is widely used in cable TVs & analog TV networks.

The advantages of the coaxial cable include high bandwidth, noise immunity is good, low cost and simple to install. The disadvantage of this cable is, the failure of cable can disturb the whole network

  Optical Fibre Cable

This cable uses the notion of light reflected through a core that is made with plastic or glass. The core is enclosed with less thick plastic or glass and it is known as the cladding, used for large volume data transmission.

The main advantages of this cable include lightweight, capacity & bandwidth will be increased, signal attenuation is less, etc. The disadvantages are high cost, fragile, installation & maintenance is difficult and unidirectional.

Unguided Media

It is also known as unbounded otherwise wireless transmission media. It doesn’t require any physical medium to transmit electromagnetic signals. The main features of this media are less secure, the signal can be transmitted through air, and applicable for large distances. There are three types of unguided media which are discussed below.

 Radiowaves

These waves are very easy to produce as well as penetrate through buildings. In this, the transmitting & receiving antennas no need to align. The frequency range of these waves ranges from 3 kHz to 1GHz. These waves are used in AM & Fm radios for transmission. These waves are classified into two types namely Terrestrial & Satellite.

 Microwaves

It is a sightline transmission which means the transmitting & receiving antennas need to align correctly with each other. The distance which is covered through the signal can be directly proportional to the antenna’s height. The frequency range of microwaves ranges from 1GHz to 300GHz. These are extensively used in TV distribution & mobile phone communication

 Infrared Waves

Infrared (IR) waves are used in extremely small distance communication as they cannot go through obstacles. So it stops intrusion between systems. The range of frequency of these waves is 300GHz to 400THz. These waves are used in TV remotes, keyboards, wireless mouse, printer, etc.

Some Factors

The following factors must be considered to design the transmission media like the following.

 Bandwidth

The bandwidth mainly refers to the capacity of data-carrying in a medium otherwise a channel. So, high BW communication channels mainly support high data rates.

 Radiation

The radiation refers to the signal leakage from the medium because of its unwanted electrical characteristics.

 Absorption of Noise

The absorption of noise refers to the vulnerability of the media to exterior electrical noise. This noise can cause data signal distortion.

 Attenuation

Attenuation refers to the energy loss when signal broadcasts externally. The loss of energy amount mainly depends on frequency. Radiation, as well as physical media characteristics, contributes to attenuation.

Transmission Impairment Causes

The transmission impairment mainly causes because of the following reasons.

 Attenuation

It is the loss of energy which can be occurred due to the decrease in signal & increase in the distance.

 Distortion

Distortion mainly occurs because of the change in signal shape. This kind of distortion can be observed from various signals which have different frequencies. Every frequency component has its separate propagation speed because they arrive at a different time which leads to the delay in distortion.

 Noise

When data is transmitted above a transmission medium, an unwanted signal can be added to it. So the noise can be created.

FAQs

1). What is transmission media?

Transmission media is a path that transmits the data from a transmitter to the receiver.

2). What are the types of transmission media?

The two types of transmission media are guided and unguided.

3). What are twisted pair cables?

Unshielded twisted pair & shielded twisted pair

4). What are the examples of transmission media?

They are coaxial cable, twisted-pair cable, and fiber optic cable

5). Mention the most commonly used transmission media in homes?

They are coaxial cable, twisted-pair, satellite, fiber optics & microwave,

Thus, this is all about transmission media and there are some factors that are considered when choosing a transmission Medium like rate of transmission, cost, simple installation, and distances. Here is a question for you, what are the examples of transmission media?

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