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The communication system is a system of information exchange between two parties. Communication is the process of transmission and reception of information. The transmitter, the channel and the receiver form a significant part of the communication system.
Frequency modulation is an integral part of the communication system as this technology is used in various fields like telecommunication, radio broadcasting, signal processing, and computing.
Frequency modulation is subdivided into definition, types, advantages, disadvantages and applications.
Modulation and its types
Modulation is the essential requirement for transmitting the message signal through a channel. It is the transmission of a low-frequency information signal using a high-frequency carrier signal.
If the variation in the carrier parameter is continuous and in accordance with the input signal, the modulation technique is divided into the following categories.
Amplitude modulation (AM):
Amplitude modulation encodes information in a carrier wave by varying the wave’s amplitude.
Frequency modulation (FM):
Frequency modulation is the encoding of information in a carrier wave by varying the frequency of the wave
Phase modulation (PM):
Phase modulation is the encoding of information in the carrier wave by varying the phase of the wave
Frequency modulation definition
Frequency modulation is the process by which the frequency of a carrier signal changes with respect to the modulating signal. FM modulated signal is a nonlinear function of modulating signal.
Types of frequency modulation
- Narrowband Frequency modulation means that the FM modulated wave has a narrow bandwidth. The maximum frequency deviation is 3kHz.
- Wideband frequency modulation means that the FM modulated wave has a wide bandwidth. Modulation frequency ranges from 30Hz to 15kHz, and the minimum deviation is 75kHz.
Advantages of Frequency Modulation
- The amplitude of the frequency-modulated wave does not get affected.
- Frequency Modulation decreases the noise; hence, there is a significant increase in the signal to noise ratio.
- We can also reduce the noise by increasing the frequency deviation.
- It also reduces the interference by the adjacent channels through guard bands.
- It operates in a very high frequency called VHF.
- It is resistant to single strength variations.
- It does not require a linear amplifier in the transmitter.
Disadvantages of frequency modulation
- FM cannot cover large areas.
- Transmitting and receiving equipment of frequency modulation is complex and expensive.
- Generally, wider channels, 200kHz, are required for FM.
- The antennas for FM need to be closely placed for better signals.
Applications of frequency modulation
- It is used in video cassette recorders.
- It is used to store luminous parts in VHS.
- It works as a limiter and also helps to remove pre-echo.
- It is used in radio broadcasts and satellite TV.
- It is used for audio frequency synthesis.
- It is used to broadcast analogous TV sound.
Comparison between frequency modulation and phase modulation
- In FM, amplitude and phase remain constant, while in PM, the frequency and amplitude remain constant.
- Frequency modulation and phase modulation both are proportional to the modulating voltage.
- FM is associated with the change in frequency, while PM is related to the change in phase.
- It is possible to receive a FM on a PM receiver, and it is also possible to receive a PM signal on an FM receiver.
- The amplitude of the PM and FM wave is constant.
- FM provides high-quality received signals while PM provides low-quality, received signals
- The signal-to-noise ratio is better in FM compared to PM.
Comparison between frequency modulation and amplitude modulation
In AM, modulation in amplitude occurs, while in FM, modulation in frequency occurs.
In FM, amplitude and phase remain constant, while frequency and phase remain constant in AM.
AM has poor sound quality compared to FM
- FM is more expensive as compared to AM.
- AM can be transmitted over a long distance and have a low bandwidth as compared to FM.
Frequency demodulation
Frequency demodulation is an essential process. It is the reversal of modulation. In this process, the retrieval of information from the carrier wave occurs at the receiver end of the channel.
A demodulator is an electronic circuit used to recover the original information from a carrier wave.
Conclusion
Frequency modulation is a very important subtype of modulation. It forms a very integral part of our day-to-day life. It is most frequently used in radio broadcasting and satellite TV.
Frequency modulation has both advantages and disadvantages, just like any other modulation system. It provides a high sound-to-noise ratio with very low interference, the reason why it is used in a radio broadcasts. One of the most significant drawbacks is that it does not cover a large area, and the system is very costly and complex.
