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Electrical measurements MCQ Quiz Hub
Digital Communications MCQs set-4
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1. The main sources of corruption are
Sampling and quantizing effects
Channel effects
Sampling, quantizing and channel effects
None of the mentioned
2. The distortion in quantization is called as
Round off error
Truncation error
Round off & Truncation error
None of the mentioned
3. In quantization process, the amount of quantization noise is _______________ to number of levels.
Directly proportional
Inversely proportional
Independent
None of the mentioned
4. Saturation noises can be avoided or reduced by
Automatic gain control
Amplifying
Filtering
None of the mentioned
5. Timing jitter can be reduced by
Good power supply isolation
Stable clock reference
Good power supply isolation & Stable clock reference
None of the mentioned
6. The reasons for the threshold effect are
Thermal noise
Interference from other users
Interference from circuit switching transients
All of the mentioned
7. When channel bandwidth is greater than the pulse bandwidth, it causes
Intersignal interference
Intersymbol interference
Bandwidth error
None of the mentioned
8. The _____________ corresponds to average quantization noise power.
Mean
Variance
Probability density function
None of the mentioned
9. Signal to noise ratio increases as ___________ increases.
Quantization level
Square of quantization level
Square root of quantization level
None of the mentioned
10. Signal to noise ratio is infinite when
Quantization noise is zero
Number of levels are infinite
Quantization noise is zero & Number of levels are infinite
None of the mentioned
11. The length of the code-word obtained by encoding quantized sample is equal to
l=log(to the base 2)L
l=log(to the base 10)L
l=2log(to the base 2)L
l=log(to the base 2)L/2
12. Quantization noise can be reduced by ________ the number of levels.
Decreasing
Increasing
Doubling
Squaring
13. In PCM encoding, quantization level varies as a function of ________
Frequency
Amplitude
Square of frequency
Square of amplitude
14. What is bit depth?
Number of quantization level
Interval between two quantization levels
Number of possible digital values to represent each sample
None of the mentioned
15. Choosing a discrete value that is near but not exactly at the analog signal level leads to
PCM error
Quantization error
PAM error
Sampling error
16. In PCM the samples are dependent on ________
Time
Frequency
Quanization leavel
Interval between quantization level
17. DPCM encodes the PCM values based on
Quantization level
Difference between the current and predicted value
Interval between levels
None of the mentioned
18. Delta modulation uses _____ bits per sample.
One
Two
Four
Eight
19. Sample resolution for LPCM ____ bits per sample.
8
16
24
All of the mentioned
20. Adaptive DPCM is used to
Increase bandwidth
Decrease bandwidth
Increase SNR
None of the mentioned
21. The size of the quantile interval is called as
Inter level
Step size
Quantile size
Level width
22. Uniform quantization provides better quantization for
Weak signals
Strong signals
Weak & Strong signals
None of the mentioned
23. Non uniform quantization provides better quantization for
Weak signals
Coarse signals
Weak & Coarse signals
None of the mentioned
24. In non uniform quantization, the quantization noise is _______ to signal size.
Inversely proportional
Directly proportional
Equal
Double
25. The output SNR can be made independent of input signal level by using
Uniform quantizer
Non uniform quantizer
Uniform & Non uniform quantizer
None of the mentioned
26. Companding is the process of
Compression
Expansion
Compression & Expansion
None of the mentioned
27. Which value of μ corresponds to linear amplification?
μ=0
μ=1
μ>0
μ<0
28. What is the standard value of μ in μ-law ?
128
255
256
0
29. The standard value of A in A-law is
87
88
86.7
87.6
30. Which type of quantization is most preferable for audio signals for a human ear?
Uniform quantization
Non uniform quantization
Uniform & Non uniform quantization
None of the mentioned
31. Which waveforms are also called as line codes?
PCM
PAM
FM
AM
32. When pulse code modulation is applied to non binary symbols we obtain waveform called as
PCM
PAM
M-ary
line codes
33. Examples of PCM waveforms are
Non return to zero
Phase encoded
Multilevel binary
All of the mentioned
34. Which type is used and preferred in digital logic circuits?
NRZ-L
NRZ-M
NRZ-S
None of the mentioned
35. Which method is called as differential encoding?
NRZ-L
NRZ-M
NRZ-S
None of the mentioned
36. Which method is preferred in magnetic tape recording?
NRZ-L
NRZ-M
NRZ-S
None of the mentioned
37. NRZ-S is complement of _______
NRZ-L
NRZ-M
NRZ-L & NRZ-M
None of the mentioned
38. The return to zero waveform consists of
Unipolar RZ
Bipolar RZ
RZ-AMI
All of the mentioned
39. Phase encoded group consists of
Manchester coding
Bi-phase-mark
Miller coding
All of the mentioned
40. In which waveform logic 1 is represented by half bit wide pulse and logic 0 is represented by absence of pulse?
Unipolar RZ
Bipolar RZ
RZ-AMI
Manchester coding
41. In which waveform logic 1 and logic 0 are represented by opposite one half bit wide pulses?
Unipolar RZ
Bipolar RZ
RZ-AMI
Manchester coding
42. In which waveform logic 1 is represented by equal amplitude alternating pulses?
Unipolar RZ
Bipolar RZ
RZ-AMI
Manchester coding
43. Application of phase encoded binary signals are
Optical communication
Magnetic recording
Satellite telemetry
All of the mentioned
44. In which waveform one is represented by half bit wide pulse positioned during the first half and zero is represented by half bit wide pulse positioned in the second half?
Bi-p-L
Bi-p-M
Bi-p-S
Delay modulation
45. Which binary waveform uses three levels?
Bipolar RZ
RZ-AMI
Bipolar RZ & RZ-AMI
None of the mentioned
46. Which waveform type has the feature of clocking?
Manchester coding
Bbi-p-M
Delay modulation
NRZ-L
47. Which waveform has the feature of error detection?
NRZ-L
RZ-AMI
Manchester coding
Duobinary
48. Which waveform scheme introduces bandwidth compression?
Duobinary
Manchester coding
Phase encoded waveform
Multilevel codes
49. Which waveform type has better noise immunity?
NRZ
RZ
Phase encoded
Multilevel codes
50. In pulse modulation, reciprocal of T(time) is
Bandwidth
Symbol rate
Signal voltage
None of the mentioned
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