Noise refers to any such signal which is undesirable, unpredictable, and random or causing a change in signals resulting in masking the desired information content. Noise sources are the origin of such noises. They can be further classified as follows:
- Communication Hardware noise sources
- Natural noise sources
- Man-made noise sources
- Inadvertent noise sources
The above mentioned sources of noises are discussed below.
Communication Hardware noise sources
This kind of noise generally originates at the radio receiver front end. It is caused due to the electronic circuits near the input stages of a radio receiver. Whenever an electric current passes through any electronic device such as transistor etc. it produces a certain amount of noise. This happens due to the unevenness of the movement of electrons.
Different types of semiconductor material used in the making of transistors contribute different quantum to the noise. The noise generated at the end of the radio receiver determines the noise floor of the radio receiver.
Natural Noise sources
Factors such as weather, atmospheric noise, galactic noise, and system noise contribute to radio interference. All such factors are classified under the head of Natural Noise sources. These sources do not generally cause radio interference.
They are largely dependent on frequency. The magnitude of natural noise is significant at High Frequency and less at Very High frequency and Ultra High Frequency.
Man-made Noise sources
Another category of external radio frequency noise is Man-made noise sources. The magnitude of man-made noise is more in urban areas, and it gradually reduces when we move towards suburban and rural areas.
Some examples of man-made sources of noise are as follows: power grid transmission, Industrial machinery, domestic appliances, etc. These sources are spread across a wide frequency spectrum.
However, the impact of these noises gradually decreases with the increase in frequency. It is more in case of high frequency and less susceptible in case of Very High Frequency and Ultra High Frequency.
Inadvertent Noise sources
Most of the amateur radio stations often pick additional noise. The main reason behind this is the poorly configured transmission lines and antennas. An improper set of transmission may line lead to noise due to imbalances giving rise to common mode currents.
Poorly set up station equipment also give rise to elevated noise issues. This happens because of the inefficiency of radio stations and their poor deployment practices.
How to reduce noise during transmission
- There should not be a flaw in the engineering design of the antenna system or its installation.
- There is a proper distance between the antenna and the operating position.
- Check the power supply ground.
- The engineering design of the radio equipment should not be poor.
- Check whether Connectors and cables are installed properly.
With the steps mentioned above, the noise transmission from the noise sources can be reduced but cannot be avoided.
To Sum it up
Noise sources affect radio transmission during communication. To reduce the interference, there is a need to reduce the magnitude of the noise from these sources. This can be done by the installation of properly designed equipment, antennas, and cables. It was also noticed that High-Frequency transmission is likely to get more affected in comparison to the Very High Frequency and Ultra High-frequency transmission.