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प्रश्न
Explain the process of amplitude modulation.
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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
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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.
An amplitude modulated wave is as shown in figure. Calculate
- the percentage modulation
- peak carrier voltage and
- peak value of information voltage.
Draw the plot of amplitude versus ‘ω’ for an amplitude modulated wave whose carrier wave (ωc) is carrying two modulating signals, ω1 and ω2 (ω2 > ω1).
- Is the plot symmetrical about ωc? Comment especially about plot in region ω < ωc.
- Extrapolate and predict the problems one can expect if more waves are to be modulated.
- Suggest solutions to the above problem. In the process can one understand another advantage of modulation in terms of bandwidth?
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 ______.
