Question
For an amplitude modulated wave, the maximum amplitude is found to be 10 V while the minimum amplitude is found to be 2 V. Determine the modulation index, μ. What would be the value of μ if the minimum amplitude is zero volt?
Solution
Let, Ac and Am be the amplitude of carrier wave and message signal wave.
Given,
Amax = Ac + Am = 10 V
Amin = AC - Am = 2V
On solving the above equations, we get
AC = 6V ; Am = 4V
Amax = 6+4 = 10 V
Amin = 6-4 = 2 V
The maximum amplitude is M1 = Ac + Am while the minimum amplitude is M2 = Ac - Am.
Hence, the modulation index is
With M2 = 0, clearly, μ = 1, irrespective of M1.
Given,
Amax = Ac + Am = 10 V
Amin = AC - Am = 2V
On solving the above equations, we get
AC = 6V ; Am = 4V
Amax = 6+4 = 10 V
Amin = 6-4 = 2 V
The maximum amplitude is M1 = Ac + Am while the minimum amplitude is M2 = Ac - Am.
Hence, the modulation index is
With M2 = 0, clearly, μ = 1, irrespective of M1.
