# Coherent Detection of DSBSC Waves MCQ’s

This set of Analog Communication Multiple Choice Questions & Answers (MCQs) focuses on “Coherent Detection of DSBSC Waves”.

1. Calculate the Nyquist rate for the signal x(t) = 12cos50πt + 7 cos75π t – 13 cos100πt.
a) 300 Hz
b) 600 Hz
c) 100 Hz
d) 150 Hz

2. What is the need of doing Pre emphasis?
a) For boosting of modulating signal voltage
b) For boosting of modulating signal frequency
c) For removing amplitude variations due to noise
d) For removing frequency variations

3. Which among the following is the drawback of Pulse Position Modulation (PPM)?
a) Synchronization is required between receiver and transmitter
b) Synchronization is not required between receiver and transmitter
c) Amplitude is constant
d) Instantaneous power of PPM modulated signals is constant

4. Amount of data transmitted for a given time is called _________
a) Noise
b) Frequency
c) Bandwidth
d) Power

5. A superheterodyne receiver receives signal within frequency range of 120 to 180 MHz. Then the required Intermediate frequency is _________
a) 30MHz
b) 60MHz
c) 90MHz
d) 50MHz

6. What is the bandwidth of a FM wave when maximum allowed deviation is 50KHz and the modulating signal has a frequency of 15KHz?
a) 130 KHz
b) 260 KHz
c) 65 KHz
d) 50 KHz

7. Consider an AM broadcast station that transmits modulating frequencies up to 10kHz. If it transmits a frequency of 1000 kHz. Find its maximum and minimum upper and lower sidebands frequencies and also the total bandwidth?
a) 900 KHz, 820 KHz, 1000 Hz
b) 720 KHz, 650 KHz, 1020 Hz
c) 1010 KHz, 880 KHz, 15000 Hz
d) 1010 KHz, 990 KHz, 20000 Hz

8. Carson’s rule is used to calculate ________
a) Bandwidth of FM signal
b) SNR
c) Modulation index of FM signal
d) Figure of merit

9. For signal, m(t) = 50cos(10 × 90t + 30 sin100t), the power dissipated by the 20Ω resistor is ________
a) 100W
b) 65W
c) 74.7W
d) 62.5W

10. Signal and its Hilbert transform have ________
a) same energy density spectrum
b) same power
c) a phase difference of 60°
d) a phase difference of 120°