Digital Communication System MCQs

Question 1

In a TDM system, different signals are distinguished from each other

Accepted Answer

in amplitude

Answer

only in time

Answer

only in frequency

Answer

both in time and frequency

Question 2

Quadrature multiplexing is a form of

Accepted Answer

none of the above

Answer

time division multiplexing

Answer

frequency division multiplexing

Answer

combined time and frequency division multiplexing

Question 3

Synchronous Time Division multiplexing is called synchronous because

Accepted Answer

None of the above

Answer

Synchronous transmission is used

Answer

Time slots are pre-assigned to sources and fixed

Answer

Synchronous durawn is used

Question 4

If a 20 kHz audio signal is to be sent accurately with an 8?bit PCM digital signal, how often (in microseconds) should the audio signal be sampled?

Accepted Answer

once every 25 microseconds

Answer

25 times every microsecond

Answer

once every 50 microseconds

Answer

10 times every microsecond

Question 5

What type of modulation would be performed by a voltage-to-frequency converter?

Accepted Answer

Frequency Modulation

Answer

Amplitude Modulation

Answer

Phase Modulation

Answer

Pulse Code Modulation

Question 6

A PCM system involves following conversion

Accepted Answer

Analog to binary codes

Answer

Voltage of frequency

Answer

Analog to pulse widths

Answer

Serial digital to parallel digital data

Question 7

If the digital '1' level is represented by +5 V and the digital '0' is represented by 1V, the noise margin in volts is given by

Accepted Answer

2 volts

Answer

6 volts

Answer

4 volts

Answer

none of these

Question 8

Time division multiplexing (TDM) allows

Accepted Answer

all of above

Answer

several subsystems to share the same transmitter facilities

Answer

different time slots to be used by different communications -

Answer

only one carrier frequency to be used to handle many communicators

Question 9

Frequency division multiplexing (FDM) allows

Accepted Answer

all of above

Answer

several subsystems to use same transmitter facilities

Answer

different frequency ranges to beused by different communicators

Answer

several communicators communicate simultaneously using same transmitter