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कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान 2nd PUC Class 12

An amplitude modulated wave is as shown in figure. Calculate (i) the percentage modulation, (ii) peak carrier voltage and, (iii) peak value of information voltage.

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प्रश्न

An amplitude modulated wave is as shown in figure. Calculate

  1. the percentage modulation
  2. peak carrier voltage and
  3. peak value of information voltage.

दीर्घउत्तर
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उत्तर

From the figure

`V_(max) = 100/2 = 50V, V_(min) = 20/2 = 10  V`.

i. Percentage modulation = `mu(%) = (V_(max) - V_(min))/(V_(max)  + V_(min)) xx 100`

= `((50  - 10)/(50 + 10)) xx 100`

= `40/60 xx 100`

= 66.67%

ii. Peak carrier voltage = `V_c = (V_(max) + V_(min))/2`

= `(50 + 10)/2`

= 30 V

iii. Peak information voltage = `V_m = muV_c`

= `2/3 xx 30`

= 20 V.

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पाठ 15: Communication Systems - Exercise [पृष्ठ १०४]

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एनसीईआरटी एक्झांप्लर Physics Exemplar [English] Class 12
पाठ 15 Communication Systems
Exercise | Q 12.28 | पृष्ठ १०४

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संबंधित प्रश्‍न

Explain any two factors that justify the need of modulating a low-frequency signal.


Explain the process of amplitude modulation.


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?


How is amplitude modulation achieved?


Explain any two factors which justify the need for modulating a low frequency base-band signal.


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.


What is meant by term ‘modulation’? Draw a block diagram of a simple modulator for obtaining an AM signal.


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.


A message signal of frequency ωm is superposed on a carrier wave of frequency ωc to get an amplitude modulated wave (AM). The frequency of the AM wave will be ______.


Why is a AM signal likely to be more noisy than a FM signal upon transmission through a channel?


Draw the plot of amplitude versus ‘ω’ for an amplitude modulated wave whose carrier wave (ωc) is carrying two modulating signals, ω1 and ω22 > ω1). 

  1. Is the plot symmetrical about ωc? Comment especially about plot in region ω < ωc.
  2. Extrapolate and predict the problems one can expect if more waves are to be modulated.
  3. Suggest solutions to the above problem. In the process can one understand another advantage of modulation in terms of bandwidth?

An amplitude-modulated wave is represented by Cm(t) = 10(1 + 0.2 cos 12560t) × sin (111 × 104t) volts. The modulating frequency in kHz will be ______.


The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be ______.


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 ______.


A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. The frequencies of the resultant signal are ______. 


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