Performance Comparison of FM and AM System

Performance Comparison of FM and AM System


In this post I am gonna compare FM & AM systems.

DRex Electronics

I know you are aware of this, nevertheless, I must tell that FM stands for Frequency Modulation whereas AM stands for Amplitude Modulation. So, it is quite obvious that FM deals with modulation of frequency whereas AM deals with modulation of frequency.

S.No                                  FM                                    AM
1. Amplitude of FM wave is constant. It is independent of the modulation index. Amplitude of AM wave will change with the modulating voltage.
2. Hence, transmitted power remains constant. It is independent of mf . Transmitted power is dependent on the modulation index.
3. All the transmitted power is useful. Carrier power and one sideband power are useless.
4. FM receivers are immune to noise. AM receivers are not immune to noise.
5. It is possible to decrease noise further by increasing deviation. This feature is absent in AM.
6. Bandwidth = 2[Δf+fm]. The bandwidth depends on modulation index. Bandwidth = 2fm . It is not dependent on the modulation index.
7. BW is large. Hence, wide channel is required. BW is much less than FM.
8. Space wave is used for propagation. So, radius of transmission is limited to line of sight. Ground wave and sky wave propagation is used. Therefore, large area is covered than FM.
9. Hence, it is possible to operate several transmitters on same frequency. Not possible to operate more channels on same frequency.
10. FM transmission and reception equipment are more complex. AM equipments are less complex.
11. The number of sidebands having significant amplitudes depends on modulation index mf . Number of sidebands in AM will be constant and equal to 2.
12. The information is contained in the frequency variation of the carrier. The information is contained in the amplitude variation of the carrier.
13. FM Wavefm wave AM Wave :am wave
14. Applications :Radio, TV broadcasting, police wireless, point to point communications Applications: Radio and TV broadcasting.

I know the above chart is not exhaustive, hence I am open to suggestions.

Please feel free to contact me, if I missed anything.