ECE · all questions

Communication Systems
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Q221

A signal m(t), band-limited to a maximum frequency of 20 kHz is sampled at a frequency f_s kHz to generate s(t). An ideal low pass filter having cut-off frequency 37 kHz is used to reconstruct m(t) from s(t). The minimum of f_s required to reconstruct m(t) without distortion is

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Q222

A message signal m(t) = A_msin(2πf_mt) is used to modulate the phase of carrier A_ccos(2πf_ct) to get the modulated signal y(t) = A_ccos(2πf_ct + m(t)). The bandwidth of y(t)

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Q223

A bandlimited signal is sampled at the Nyquist rate. The signal can be recovered by passing the samples through

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Q224

An FM signal is being broadcast in the 88-108 MHz band having a carrier swing of 125 kHz. The percentage of modulation is

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Q225

Hilbert transform of Acos(2πf₀t + θ) is

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Q226

Boosting of higher frequency at the transmitter is done by using

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Q227

A signal contains components at 400 Hz and 2400 Hz. This signal modulates a carrier of frequency 100 MHz. However after demodulation it is found that the 400 Hz signal component is present. The channel Bandwidth is 15 KHz. What is the reason for the higher frequency signal not to be detected properly.

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Q228

Match List-I with List-II and select the correct answer using the options given below:

List-I	List-II
a. SSB	1. Envelope detector
b. AM	2. Integrate and dump
c. BPSK	3. Hilbert transform

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