. Differentiate between AM and FM
AM and FM
i. In amplitude modulation only there are three frequencies, the carrier and the first two side bands.
ii. In frequency modulation there are infinite number of side bands, as well as the carrier. The side bands are separated from the carrier by fm, 2fm, 3 fm, .. and thus have frequency fm.
iii. In amplitude modulation, increased depth of modulation increases the side bands power and, therefore, the total transmitted power.
iv. In frequency modulation, the total transmitted power always remains constant; but with increased depth of modulation the required bandwidth is increased.
v. FM broadcast operate in VHF and UHF frequency range. AM broadcast is usually in MF (Medium frequency) and HF(High frequency).
vi. In FM broadcast, magnitude of noise is comparatively larger than AM broadcast.
vii. In FM wave noise can be reduced by increasing deviation. This feature is not available in AM wave, as depth of amplitude modulation can not be increased beyond 100% without causing distortion.
viii. The channel width required by FM is upto 10 times as large as that needed by AM.
ix. The area of reception for FM is much smaller than for AM, as reception in FM is limited to the line of sight.