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प्रश्न
In the block diagram of a simple modulator for obtaining an AM signal, shown in the figure, identify the boxes A and B. Write their function.
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उत्तर
In the block diagram of modulator, A is Square Law Device and B is Band pass filter.
Band pass filter rejects low and high frequencies and allows a band of frequencies to pass through.
Square law device is a non linear device. It produces a non-linear output of message and carrier signals. The output from square law device is,
y(t)=Bx(t)+Cx2(t)
Where, B and C are constants and x(t)=message signal (Amsinωmt) + carrier signal (Acsinωct)
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संबंधित प्रश्न
The process of superimposing a low frequency signal on a high frequency wave is_______ .
The carrier wave is given by
C(t) = 2sin(8πt) volt.
The modulating signal is a square wave as shown. Find modulation index.
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A carrier wave of peak voltage 15 V is used to transmit a message signal. Find the peak voltage of the modulating signal in order to have a modulation index of 60%
State any two types of modulation
The carrier wave is represented by
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An audio signal of 15kHz frequency cannot be transmitted over long distances without modulation because ______.
- the size of the required antenna would be at least 5 km which is not convenient.
- the audio signal can not be transmitted through sky waves.
- the size of the required antenna would be at least 20 km, which is not convenient.
- effective power transmitted would be very low, if the size of the antenna is less than 5 km.
A carrier wave Vc(t) = 160 sin(2π × 106t) volts is made to vary between Vmax = 200 V and Vmin = 120 V by a message signal Vm(t) = Am sin(2π × 103t) volts. The peak voltage Am of the modulating signal is ______.
