Worksheetsacs unit 1
Total questions: 20
Worksheet time: 7mins
Name
Class
Date
1.
In digital modulation, the digital data modulates which type of signal?
a)
A DC level
b)
A sinusoidal carrier
c)
A square pulse
d)
Random noise
e)
Not applicable
2.
The purpose of a carrier in digital modulation is:
a)
To reduce power
b)
To reduce bandwidth
c)
To shift data into passband
d)
To add noise
e)
Not applicable
3.
Amplitude modulation in analog systems corresponds to which digital scheme?
a)
ASK
b)
FSK
c)
PSK
d)
QAM
e)
Not applicable
4.
Frequency modulation in analog corresponds to:
a)
QPSK
b)
ASK
c)
FSK
d)
QAM
e)
Not applicable
5.
Phase modulation in analog corresponds to:
a)
QAM
b)
PSK
c)
FSK
d)
ASK
e)
Not applicable
6.
Quadrature Amplitude Modulation (QAM) combines:
a)
ASK and FSK
b)
ASK and PSK
c)
FSK and PSK
d)
PSK and DPSK
e)
Not applicable
7.
Digital modulation is used mainly to:
a)
Reduce frequency
b)
Increase distance of communication
c)
Increase noise
d)
Eliminate modulation
e)
Not applicable
8.
Baseband transmission differs from bandpass transmission by:
a)
Using a carrier
b)
Not using a carrier
c)
Using frequency shifts
d)
Using phase shifts
e)
Not applicable
9.
Which is NOT a digital modulation scheme?
a)
ASK
b)
FSK
c)
QAM
d)
AM
e)
Not applicable
10.
Digital modulation is preferred in modern systems because:
a)
It increases distortion
b)
It reduces noise immunity
c)
It allows high speed data
d)
It avoids all errors
e)
Not applicable
11.
ASK modulation is also called:
a)
Phase keying
b)
On-Off Keying
c)
Frequency keying
d)
Quadrature modulation
e)
Not applicable
12.
In ASK, when binary input is 1:
a)
Carrier is blocked
b)
Carrier is transmitted
c)
No signal appears
d)
Noise is transmitted
e)
Not applicable
13.
In ASK, when binary input is 0:
a)
Carrier is transmitted
b)
Carrier is blocked
c)
Frequency is doubled
d)
Phase is shifted
e)
Not applicable
14.
ASK suffers most from:
a)
Phase noise
b)
Amplitude noise
c)
Frequency drift
d)
None
e)
Not applicable
15.
ASK is suitable for:
a)
Optical fiber
b)
Radio broadcasting
c)
Wi-Fi
d)
Satellite uplink
e)
Not applicable
16.
Which device generates carrier in ASK modulator?
a)
Amplifier
b)
Oscillator
c)
Detector
d)
Phase shifter
e)
Not applicable
17.
Which component removes unwanted signal in ASK demodulator?
a)
High pass filter
b)
Band reject filter
c)
Low pass filter
d)
Amplifier
e)
Not applicable
18.
ASK is less preferred because:
a)
It needs high bandwidth
b)
It is highly noise sensitive
c)
It requires complex receiver
d)
It needs phase recovery
e)
Not applicable
19.
ASK uses which parameter of carrier?
a)
Amplitude
b)
Frequency
c)
Phase
d)
None
e)
Not applicable
20.
ASK demodulator uses which circuit to synchronize carrier?
a)
PLL
b)
Oscillator
c)
Rectifier
d)
Mixer
e)
Not applicable
100 %
