21. A signal m(t), band-limited to a maximum frequency of 20 kHz is sampled at a frequency fs 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 fs required to reconstruct m(t) without distortion is
22. A message signal m(t) = Amsin(2πfmt) is used to modulate the phase of carrier Accos(2πfct) to get the modulated signal y(t) = Accos(2πfct + m(t)). The bandwidth of y(t)
23. A bandlimited signal is sampled at the Nyquist rate. The signal can be recovered by passing the samples through
24. An FM signal is being broadcast in the 88-108 MHz band having a carrier swing of 125 kHz. The percentage of modulation is
25. Hilbert transform of Acos(2πf0t + θ) is
26. Boosting of higher frequency at the transmitter is done by using
27. 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.
28. 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
| List-I | List-II |
| a. SSB | 1. Envelope detector |
| b. AM | 2. Integrate and dump |
| c. BPSK | 3. Hilbert transform |
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