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MCQS
Electrical measurements MCQ Quiz Hub
Digital Communications MCQs set-7
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1. M-ary signalling produces _______ error performance with orthogonal signalling and _______ error performance with multiple phase signalling.
Degraded, improved
Improved, degraded
Improved, improved
Degraded, degraded
2. Which is more vulnerable to noise?
2-ary system
4-ary system
Binary system
None of the mentioned
3. In which system, bit stream is portioned into even and odd stream?
BPSK
MSK
QPSK
FSK
4. The error performance of MPSK ______ as M or k increases.
Increases
Decreases
Stays constant
None of the mentioned
5. In MPSK adding new signals _______ make it vulnerable to noise and in MFSK _______ make it vulnerable.
Does, does not
Does not, does
Does, does
Does not, does not
6. In orthogonal signalling with symbols containing more number of bits we need ____ power.
More
Less
Double
None of the mentioned
7. For FSK signalling, WT is equal to
0
1
0.737
Infinity
8. Energy per symbol Es is given as
Es=Eb(log2M)
Es=Eb/(log2M)
Es=2Eb(log2M)
Es=Eb/2(log2M)
9. The relation between the probability of bit error and probability of symbol error in M-ary orthogonal signalling is
M/M-1
2M/M-1
(M/2)/M-1
M/M+1
10. As limit of k increases, the ratio of PB/PE becomes
1:2
2:1
1:3
3:1
11. Link budget consists of calculation of
Useful signal power
Interfering noise power
Useful signal & Interfering noise power
None of the mentioned
12. Link budget can help in predicting
Equipment weight and size
Technical risk
Prime power requirements
All of the mentioned
13. Which is the primary cost for degradation of error performance?
Loss in signal to noise ratio
Signal distortion
Signal distortion & Loss in signal to noise ratio
None of the mentioned
14. Which factor adds phase noise to the signal?
Jitter
Phase fluctuations
Jitter & Phase fluctuations
None of the mentioned
15. Antennas are used
As transducer
To focus
As transducer & To focus
None of the mentioned
16. Mechanism contributing to a reduction in efficiency is called as
Amplitude tapering
Blockage
Edge diffraction
All of the mentioned
17. Space loss occurs due to a decrease in
Electric field strength
Efficiency
Phase
Signal power
18. Antenna’s efficiency is given by the ratio of
Effective aperture to physical aperture
Physical aperture to effective aperture
Signal power to noise power
Losses
19. Effective radiated power of an isotropic radiator can be given as a product of
Radiated power and received power
Effective area and physical area
Transmitted power and transmitting gain
Receiving power and receiving gain
20. According to reciprocity theorem, _____ and _____ are identical.
Transmitting power and receiving power
Transmitting gain and receiving gain
Effective area and physical area
None of the mentioned
21. Field of view is ______ to antenna gain.
Proportional
Inversely proportional
Half the
Double
22. Antenna gain ______ as effective area increases.
Increases
Decreases
Remains same
None of the mentionedv
23. The beam-width becomes narrower on
Increasing frequency
Increasing antenna size
Increasing frequency & antenna size
None of the mentioned
24. Path loss Ls is dependent on
Signal power
Effective area
Wavelength
Antenna size
25. Thermal noise is generated due to
Lossy coupling
Lossless coupling
Lossy & Lossless coupling
None of the mentioned
26. In analog receivers, noise bandwidth is _________ signal bandwidth.
Lesser than
Greater than
Equal to
Not related View Answer
27. The link availability measures the percentage of time the link can be ______
Open
Closed
Used
None of the mentioned
28. Visibility is ________ to required availability.
Proportional
Inversely proportional
Equal
Not related
29. The stop and wait ARQ needs _______ connection.
Half duplex
Full duplex
Simplex
None of the mentioned
30. In continuous ARQ will pullback uses _____ system.
Half duplex
Full duplex
Simplex
None of the mentioned
31. Which method requires less redundancy?
Error detection
Error correction
Error detection & correction
None of the mentioned
32. Hybrid automatic repeat request is a combination of
ARQ and error correction code
ARQ and error detection code
Error detection and correction codes
One of the mentioned
33. Automatic repeat request is also called as
Forward error correction
Backward error correction
Forward & Backward error correction
None of the mentioned
34. Error detection is realized using
Hash function
Check sum
Hash function & Check sum
None of the mentioned
35. Check-sum scheme has
Check bits
Parity bits
Longitudinal redundancy bits
All of the mentioned
36. Example of block code is
Hamming code
Reed-solomon code
Repetition code
All of the mentioned
37. Noise figure measures the
Power degradation
Noise degradation
SNR degradation
None of the mentioned
38. Noise figure is a parameter that represents a ______ of the system.
Noisiness
Efficiency
Maximum output
Maximum power handling capacity
39. When two networks are connected in series, its composite noise figure can be given as
F1+(F2-1)/G1
F1-(F2-1)/G1
F2+(F1-1)/G1
F1G1+(F2-1)
40. The space window region ranges from
1GHz to 10 GHz
10GHz to 100GHZ
5GHz to 50GHz
1MHz to 10MHz
41. Atmospheric window region is used for
Satellite communication
Deep-space communication
Satellite & Deep-space communication
None of the mentioned
42. Which parameter is referred to as receiver sensitivity?
S/N ratio
G/T ratio
EIRP
PR/N0
43. What are the functions of satellite repeaters?
Re transmits
Regenerates
Reconstitutes
All of the mentioned
44. What are the functions of non-regenerative repeaters?
Amplifies
Re transmits
Amplifies & Re transmits
None of the mentioned
45. In which repeaters uplink is decoupled from the downlink?
Regenerative
Non regenerative
Regenerative & Non regenerative
None of the mentioned
46. AM-to-AM conversion brings about
Amplitude variation
Phase variation
Frequency variation
None of the mentioned
47. AM-to-PM conversion brings about
Amplitude variation
Phase variation
Frequency variation
None of the mentioned
48. Channel coding relates to area such as
Waveform coding
Structured sequence
Waveform coding & Structured sequence
None of the mentioned
49. Examples of structured sequences are
Block codes
Convolutional codes
Turbo codes
All of the mentioned
50. Antipodal signals are
Mirror images
1800 apart
One is negative of the other
All of the mentioned
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