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Module 3-Digital modulation techniques

Total questions: 20

Worksheet time: 10mins

Name
Class
Date
1.

In Binary Phase Shift Keying system, the binary symbols 1 and 0 are represented by carrier with phase shift of

a)

Π/2

b)

Π

c)

d)

0

2.

BPSK system modulates at the rate of

a)

1 bit/ symbol

b)

2 bit/ symbol

c)

4 bit/ symbol

d)

None of the above

3.

The binary waveform used to generate BPSK signal is encoded in

a)

Bipolar NRZ format

b)

Manchester coding

c)

Differential coding

d)

None of the above

4.

The bandwidth of BFSK is ______________ than BPSK.

a)

Lower

b)

Same

c)

Higher

d)

Not predictable

5.

The maximum bandwidth is occupied by

a)

ASK

b)

BPSK

c)

FSK

d)

None of the above

6.

BPSK uses non-coherent demodulator. State whether True or False.

a)

True

b)

False

7.

Probability density function defines

a)

Amplitudes of random noise

b)

Density of signal

c)

Probability of error

d)

All of the above

8.

In coherent detection of signals

a)

Local carrier is generated

b)

Carrier of frequency and phase as same as transmitted carrier is generated

c)

The carrier is in synchronization with modulated carrier

d)

All of the above

9.

In DPSK technique, the technique used to encode bits is

a)

AMI

b)

Differential code

c)

Uni polar RZ format

d)

Manchester format

10.

QPSK system uses a phase shift of

a)

Π

b)

Π/2

c)

Π/4

d)

11.

QPSK is a modulation scheme where each symbol consists of

a)

4 bits

b)

2 bits

c)

1 bits

d)

M number of bits, depending upon the requirement

12.

In On-Off keying, the carrier signal is transmitted with signal value '1' and '0' indicates

a)

No carrier

b)

Half the carrier amplitude

c)

Amplitude of modulating signal

d)

None of the above

13.

In non coherent reception _____ is measured.

a)

Phase

b)

Energy

c)

Power

d)

None of the mentioned

14.

QAM uses ______ as the dimensions.

a)

In phase

b)

Quadrature

c)

In phase & Quadrature

d)

None of the mentioned

15.

Which system uses QAM?

a)

Digital microwave relay

b)

Dial up modem

c)

Digital microwave relay & Dial up modem

d)

None of the mentioned

16.

DPSK uses coherent form of PSK. State whether True or False.

a)

True

b)

False

17.

On a 16-QAM constellation diagram each constellation point represents a

a)

dibit

b)

quadbit

c)

tribit

d)

pentabit

18.

In-------the phase and amplitude of the carrier signal is varied in accordance with the information signal

a)

ASK

b)

FSK

c)

PSK

d)

QAM

19.

In which system, bit stream is portioned into even and odd stream?

a)

BPSK

b)

MSK

c)

QPSK

d)

FSK

20.

Energy per symbol Es is given as

a)

Es=Eb(log2M)

b)

Es=Eb/(log2M)

c)

Es=2Eb(log2M)

d)

Es=Eb/2(log2M)