25-02-2013, 02:57 PM
Amplitude Modulation
Amplitude.pptx (Size: 241.51 KB / Downloads: 25)
Modulation
The process by which some characteristic of a signal (carrier signal) is varied in accordance with the instantaneous value of another signal called modulating or message signal.
The carrier frequency is greater than the modulating frequency.
The signal resulting from the modulation is called Modulated signal.
Need of Modulation :-
Practicality of Antenna (length of antenna ¼ of wavelength).
To remove interference .
Reduction of Noise (noise cannot be eliminated but minimized by several Modulation scheme).
Advantage of AM :
It is simple to implement .
It can be demodulated using a circuit consisting of very few components.
AM receivers are very cheap as no specialised components are needed.
Disadvantage of AM:-
It is not efficient in terms of its power usage.
It is not efficient in terms of its use of bandwidth, requiring a bandwidth equal to twice that of the highest audio frequency .
It is prone to high levels of noise because most noise is amplitude based .
Conclusion :
Though we are doing Amplitude Modulation for minimized the noise but it is not effective compare to FM & PM. As most of the noise is amplitude based , so the affect of noise is higher in AM.
Wastage of power is more in Amplitude Modulation.