Terms Used in Communication System-Noise

In this content, you will come to know about Noise. If we need to share some information with someone, we generally speak. Have you ever wondered how your voice reaches the concerned person against all external disturbances? An undesired sound usually interferes with other sounds being listened to. In Communication Systems , noise is an error or undesired random disturbance of an information signal. noise is the summation of undesired energy from natural and man-made sources too. The existence of noise will degrade the quality of the signal at the receiving point.

Noise

As discussed earlier, noise is an unwanted random signal that exists in a communication system. In other words, noise is a random fluctuation in electrical signal and varies for different devices and is produced by various effects. Noise is more significant in wireless communication systems.

A natural example of noise includes the thunderstorm, which affects communication. The man-made noises include noise from external sources such as power lines and ignition systems. The internal sources include receiving systems associated with electronic devices.

Effects of Noise

 The effects of noise are discussed below.

• Noise affects the sensitivity of the receiver system.

• The receiver cannot function properly.

• The performance of the signal in both analogue and digital systems is degraded.

• The receiver cannot get the information that the sender is sharing.

Classification of Noise 

Noise is classified into two main categories. They are Internal Noise and External Noise.

External Noise

As the name itself indicates, external noises are caused by external sources and are classified into 3 types. They are:

Atmospheric Noise

The atmospheric happenings such as lightning, thunderstorm, and other natural sources fall under this type. As the atmosphere is everywhere, its impulses are random and spread all over the spectrum.

Extraterrestrial Noise

As the name itself indicates, terrestrial refers to the outside world. Here they fall under 2 main subgroups: Solar Noise and Cosmic Noise.

• Solar Noise

The noise that is released from the sun is called solar noise.

• Cosmic Noise

The stars and other celestial bodies are present in our universe, and the noise caused by these is distributed all over the sky and is called cosmic noise.

Man-made Noise

The name itself indicates that the activities of man cause such disturbance. The noise caused by automobile ignition aircraft ignition from external power lines falls under man-made noises. It mainly happens in places where there are more industries.

Internal Noise

As the word-internal refers to things that happen in a specific environment. Here the sources of noise arise within the communication system. They fall under 4 categories which are described below.

1) Thermal Noise

2) Shot Noise

3) Transit Time Noise

4) Miscellaneous Internal Noise

Thermal Noise

• It is also known as White noise or Johnson noise.
• We know that free electrons and ions are usually present in conductors. Sometimes they collide with each other and start to vibrate. Their motion gives rise to noise, which is referred to as thermal noise.

Shot Noise

• It refers to the non-linearity in the system caused by excessive signal strength. The non linearity is caused at both the transmitter, and the receiver ends. But the output values will be the same. These are known as Shot noises.

Transmit Time Noise

• We know that a carrier is made up of holes and charges.
• Their exchange and noise require a certain duration of time created during this process, known as the Transmit time noise.

Miscellaneous internal Noise

• We will see one of the miscellaneous topics, the Flicker Noise or pink noise.
• It almost occurs everywhere in circuits, which may contain impurities. In some cases, there is noise due to some recombination processes. 

Noise Reduction Techniques

Various methods normally reduce the noise. They fall under 2 broad categories. Software method and Hardware methods. Software method refers to the various computer algorithms, while the hardware method refers to introducing devices such as filters, modulators, etc.

Conclusion 

This article has discussed the important concept of noise, its effects, and mainly the various classification of noise. Though noise is inevitable, it can be reduced by various techniques, and they are discussed above. The noise is inevitable in communication systems. A knowledge about their classification helps control noise and move to the next step of the communication process. The effects produced by the noise can be understood, and handling of these undesired signals that degrade the quality of the good signal is studied.