Digital Communication System MCQs

Question 1

The unit of energy density spectrum is

Accepted Answer

H/Hz

Answer

Hz/J

Answer

H

Answer

J

Question 2

With reference to which of the following, the effect of noise in a communication system is most adverse?

Accepted Answer

Channel

Answer

Receiver

Answer

Source

Answer

Encoder

Question 3

What is the total area under probability distribution curve?

Accepted Answer

One

Answer

Zero

Answer

Infinite

Answer

None of the above

Question 4

Autocorrelation, for a Gaussian process, also implies

Accepted Answer

statistical independence

Answer

ergodic process

Answer

statistical dependence

Answer

none of the above

Question 5

In communication, an ergodic process is present if many random signals have

Accepted Answer

identical time and ensemble averages

Answer

identical time averages

Answer

identical ensemble averages

Answer

none of the above

Question 6

In carrier system frequency frogging is used to

Accepted Answer

reduce cross talk

Answer

reduce distortion

Answer

conserve frequencies

Answer

all of the above

Question 7

The modulation system inherently most noise resistant is

Accepted Answer

pulse-code modulation

Answer

pulse-position modulation

Answer

SSB, suppressed carrier

Answer

frequency modulation

Question 8

Which of the following instruments is used in an aeroplane to measure its height aboveground?

Accepted Answer

Radar altimeter

Answer

MI!

Answer

CW radar

Answer

Doppler radar

Question 9

The grade of service is measured in

Accepted Answer

percentage

Answer

logarithmic number

Answer

number

Answer

fractional number