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Modulation Index is the ratio of the maximum deviation frequency to the frequency of modulation. In other words it is the ratio of the spread in frequency spectrum to the frequency that was used to modulate the carrier. For FM, modulation index is given by the formula mf= df/f where, mf=modulation index for FM df=difference in carrier frequency f=frequency of the signal
Deviation ratio: In a frequency modulation system, the ratio of the maximum frequency deviation of the carrier to the maximum modulating frequency of the system under specified conditions
the maximum amplitude of carrier wave varied with respect to instantaneous values of message signal is called amplitude modulation
amplitude modulating signal
If the modulation index is greater than 1 (more than 100% modulation) the modulated carrier signal is periodically reduced to zero. This does not effect the transmitter but at the receiver these "dead carrier" intervals result in dropouts in the audio stream from the loudspeaker producing a distorted output that is difficult to understand.
Modulation Index is the ratio of the maximum deviation frequency to the frequency of modulation. In other words it is the ratio of the spread in frequency spectrum to the frequency that was used to modulate the carrier. For FM, modulation index is given by the formula mf= df/f where, mf=modulation index for FM df=difference in carrier frequency f=frequency of the signal
Deviation ratio: In a frequency modulation system, the ratio of the maximum frequency deviation of the carrier to the maximum modulating frequency of the system under specified conditions
the maximum amplitude of carrier wave varied with respect to instantaneous values of message signal is called amplitude modulation
Modulation index is also called as Modulation depth. The modulation index of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its unmodulated level.
fc>2fm
A(m)/A(c)=0.5 is known as 50% modulation index. where, A(m)=amplitude of message signal A(c)=amplitude of carrier signal
amplitude modulating signal
In amplitude modulation, modulation depth refers to the ratio of the unmodulated carrier amplitude to the amplitude deviation for which the modulated carrier wave reaches its minimum value. If this minimum value is zero, the modulation depth is 100%.For amplitude modulation,modulation depth = (a-b)/(a+b),wherea is the unmodulated carrier amplitude, andb is the minimum amplitude deviation.The modulation depth ratio is also referred to as the modulation index.
If the modulation index is greater than 1 (more than 100% modulation) the modulated carrier signal is periodically reduced to zero. This does not effect the transmitter but at the receiver these "dead carrier" intervals result in dropouts in the audio stream from the loudspeaker producing a distorted output that is difficult to understand.
In amplitude modulation, modulation depth refers to the ratio of the unmodulated carrier amplitude to the amplitude deviation for which the modulated carrier wave reaches its minimum value. If this minimum value is zero, the modulation depth is 100%.For amplitude modulation,modulation depth = (a-b)/(a+b),wherea is the unmodulated carrier amplitude, andb is the minimum amplitude deviation.The modulation depth ratio is also referred to as the modulation index.
how modulation index varies for FM
how modulation index varies for FM