Difference between Frequency Modulation and Phase Modulation

Transmission is used in telecommunications and broadcasting by altering a carrier wave so that it can cover a certain distance. Transmission of information involves two common methods of modulation, that is, frequency modulation and phase modulation. While both are employed for the purpose of transmitting data, it is employed in a manner by which the characteristics of the carrier signal are altered in a way that could prove advantageous depending on the type of application it would be used for, such as radio broadcast or mobile communication. 

What is Frequency Modulation (FM)?

Frequency modulation (FM) can be described as the method in which the carrier wave frequency varies following the modulating signal amplitude. The amplitude and the phase of the carrier wave do not change at all. Among modulation schemes, FM is used most famously in radio broadcasting because of better audio frequency modulation as compared to other modulations. 

How Does Frequency Modulation Work?

In FM, the frequency of the carrier signal varies dependent on the voltage of the modulating signal that delivers the information. As evident above, while the frequency may be varying, the phase and the amplitude remain constant. This makes sure that the signals produced from the FM transmitter have better noise immunities than the AM, offering good quality of the sounds that are transmitted locally. 

Advantages of Frequency Modulation

• The Amplitude of FM wave remains constant over time. This helps in removing noise from received signal.
• FM is resistant to single strength variation.
• It enhances more efficient use of bandwidth.

Disadvantage of Frequency Modulation

• Modulation of wave increases the complexity in implementation.
• It requires specialized equipment and knowledge to implement, which makes it less accessible.
• FM has a large bandwidth which makes it costlier.

What is Phase Modulation (PM)?

With phase modulation (PM), the phase of the carrier wave only changes depending on the amplitude of the modulating signal and not the amplitude and frequency of the signal. While, comparably with FM, it is PM that is more utilized in mobile communication systems. 

How Does Phase Modulation Work?

Therefore, in PM, the phase of the carrier wave is directly proportional to the amplitude of the modulating signal. The change of phase can alter the frequency, though it means that there will always be a little overlap between the two phenomena, FM and PM. Nonetheless, the main difference here is that PM is centered around changing the phase rather than the frequency of the carrier signal.

Advantages of Phase Modulation

• Phase Modulation is used in mobile system.
• In Phase Modulation, the amplitude remains the same.

Disadvantages of Phase Modulation

• It has complex circuit.
• It has poor sound quality

Difference between Frequency Modulation and Phase Modulation

Conclusion

Both Frequency Modulation and Phase Modulation have their importance in working of communication systems. Although signal to noise ratio as well as audio quality is better with FM than that with PM, the latter is used in mobile communication systems. Comparing the two enables one to be in a position to select the appropriate modulation technique depending on the application.

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Article Tags :

• Difference Between
• Digital Logic