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# GATE 2023 Communication System Quiz 32

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Question 1

A sinusoidal message signal, m(t) = Am cos (2pfmt) is applied to a frequency modulator and a phase modulator separately. If βFM is the modulation index of the FM signal and βPM is the modulation index of the PM signal, then select the correct one of the following statements?

Question 2

An FM signal  is modulated by waveform shown in fig.

Find the value of Kf(Hz/V) so that peak-to-peak frequency deviation is 50 KHz.

Question 3

Consider an angle modulated signal x(t) = 2 cos[2π × 105t + 2cos2π × 102 t]. Let the instantaneous frequency at t = 5 m sec will be f1 and maximum frequency deviation is f2 then f1 + f2 is ______ × 102 Hz.

Question 4

A sinusoidal carrier wave of frequency of fc =100M Hz is exponentially modulated by a modulating signal x(t). find maximum and minimum instantaneous frequency.

if resulting signal is PM with sensitivity kP= 10π Hz/v

Question 5

A super heterodyne receiver having RF amplifier is tuned to 1200 kHz, the intermediate frequency is 450 kHz. The quality factor of the tuned circuit at RF amplifier and at the mixer are same and is equal to 65. The image rejection ratio is

Question 6

For an envelope detector with AWGN receiving a fine mode signal has SNR of 30dB. Assuming the modulation index of 0.8 and rms value of carrier to be 100V and message is band limited to 4kHz, The PSD of noise at the input of envelope detector would be………..(mW/Hz)
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