Advertisements
Advertisements
Question
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.
Advertisements
Solution
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)
APPEARS IN
RELATED QUESTIONS
The process of superimposing a low frequency signal on a high frequency wave is_______ .
Draw a sketch of a sinusoidal carrier wave along with a modulating signal and show how these are superimposed to obtain the resultant amplitude modulated wave
How are side bands produced?
A carrier wave of peak voltage 12 V is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of 75%?
Explain the need for modulation related to the size of antenna (aerial).
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%
The carrier wave is represented by
The carrier wave of a signal is given by C(t) = 3 sin (8πt) volt. The modulating signal is a square wave as shown. Find its modulation index.
A 20 volt AC is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 volt, the voltage across the coil is ______.
Broadcasting antennas are generally ______.
