Comparison of FM and PM Systems

FM (Frequency Modulation) and PM (Phase Modulation) are two types of angle modulation techniques used in communication systems. Here are some key differences between FM and PM:

1. Frequency Range: In FM, the frequency of the carrier signal is varied in proportion to the amplitude of the modulating signal. In contrast, in PM, the phase of the carrier signal is varied in proportion to the amplitude of the modulating signal. As a result, the frequency range of PM is limited to a smaller range compared to FM.

2. Bandwidth: The bandwidth of FM and PM signals depends on the maximum frequency deviation and the maximum modulation frequency. In general, FM signals require more bandwidth than PM signals for the same maximum deviation and maximum modulation frequency.

3. Noise Immunity: FM signals are more immune to noise and interference than PM signals. This is because the phase of the PM signal can be affected by noise or interference, while the frequency of the FM signal is less affected.

 4. Spectral Efficiency: PM is generally more spectrally efficient than FM. This is because PM can achieve a higher signal-to-noise ratio for a given bandwidth compared to FM.

5. Implementation Complexity: In general, PM is simpler to implement than FM. This is because PM only requires a single integrator to generate the modulated signal, while FM requires both an integrator and a differentiator.

Overall, both FM and PM have their own advantages and disadvantages, and the choice between the two depends on the specific requirements of the application. FM is commonly used for high-fidelity audio transmission and for some analog communication systems, while PM is commonly used in digital communication systems. 

Comparison of FM and PM Systems