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प्रश्न
Explain the process of amplitude modulation.
उत्तर
Amplitude Modulation: Amplitude modulation is produced by varying the amplitude of the carrier waves in accordance with the amplitude of the modulating wave.
Let the carrier wave be c(t) = Acsinωct and the modulating signal be m(t) = Amsinωmt where ωm = 2πfm is the angular frequency of the message signal.
Modulated signal cm(t) is
cm(t)=(Ac+Am sinωmt)sinωct
where μ = Am/Ac is the modulation index.
`c_m(t)=A_csinomega_ct+(muA_c)/2cos(omega_c-omega_m)t-(muA_c)/2cos(omega_c+omega_m)t`
ωc - ωm and ωc+ωm are the lower side and upper side frequencies, respectively.
Production of Amplitude Modulated Wave
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संबंधित प्रश्न
Draw a block diagram of a detector for AM signal and show, using necessary processes and the waveforms, how the original message signal is detected from the input AM wave.
Draw a schematic sketch showing how amplitude modulated signal is obtained by superposing a modulating signal over a sinusoidal carrier wave.
Write three important factors which justify the need of modulating a message signal. Show diagrammatically how an amplitude modulated wave is obtained when a modulating signal is superimposed on a carrier wave.
Answer the following question.
If A and B represent the maximum and minimum amplitudes of an amplitude-modulated wave, write the expression for the modulation index in terms of A and B.
Solve the following question.
A message signal of frequency 20 kHz and peak voltage 10 V is used to modulate a carrier of frequency 2 MHz and peak voltage of 15 V. Calculate the modulation index. Why the modulation index is generally kept less than one?
Identify the mathematical expression for amplitude modulated wave ______.
In amplitude modulation, the modulation index m, is kept less than or equal to 1 because ______.
- m > 1, will result in interference between carrier frequency and message frequency, resulting into distortion.
- m > 1 will result in overlapping of both side bands resulting into loss of information.
- m > 1 will result in change in phase between carrier signal and message signal.
- m > 1 indicates amplitude of message signal greater than amplitude of carrier signal resulting into distortion.
Why is a AM signal likely to be more noisy than a FM signal upon transmission through a channel?
An audio signal vm = 20sin2π(1500t) amplitude modulates a carrier vc = 80 sin 2π (100,000t). The value of percent modulation is ______.
The maximum amplitude for an amplitude modulated wave is found to be 12V while the minimum amplitude is found to be 3V. The modulation index is 0.6x where x is ______.
