Digital Communication System MCQs

Question 1

Cosmic noise is caused by

Accepted Answer

distant stars

Answer

lightning discharge

Answer

solar eruptions

Answer

none of the above

Question 2

The autocorrection function of the white noise is

Accepted Answer

impulse function

Answer

step function

Answer

constant

Answer

none of the above

Question 3

Frequency shift keying is used mostly in

Accepted Answer

telegraphy

Answer

telephony

Answer

radio transmission

Answer

none of the above .

Question 4

Thermal noise power is

Accepted Answer

proportional to B

Answer

proportional to 1/F3

Answer

proportional to 1/B2

Answer

proportional to B2

Question 5

If the sampling time is less than the Nyquist interval, then

Accepted Answer

simpler filters may be used to obtain the original signal

Answer

guard time reduces

Answer

bandwidth increases

Answer

channel capacity increases

Question 6

In order to get the original signal from the sampled signal, which of the following filters should be necessarily used?

Accepted Answer

Low pass filter

Answer

Band stop filter

Answer

High pass filter

Answer

Band pass filter

Question 7

For fast communication, which of the following requirements must be met?

Accepted Answer

Large bandwidth

Answer

High S/N ratio

Answer

High channel capacity

Answer

None of the above

Question 8

Broadband long distance communication was originally made possible by the advent of

Accepted Answer

repeater amplifie

Answer

telegraph cable

Answer

geostationary satellites

Answer

H.F. radio system

Question 9

With reference to 'Telex' which of the following statements is correct?

Accepted Answer

It is a teleprinter service between various subscribers

Answer

It is a telegraph service between various subscribers

Answer

It is telephone service between various subscribers

Answer

It is a television service between various subscribers