sinfoera.com – MCQs, Mock Tests | Electrical measurements Digital Communications MCQs set-4

1 The main sources of corruption are

A Sampling and quantizing effects B Channel effects C Sampling, quantizing and channel effects D None of the mentioned

✅ Correct Answer: 3

2 The distortion in quantization is called as

A Round off error B Truncation error C Round off & Truncation error D None of the mentioned

✅ Correct Answer: 3

3 In quantization process, the amount of quantization noise is _______________ to number of levels.

A Directly proportional B Inversely proportional C Independent D None of the mentioned

✅ Correct Answer: 2

4 Saturation noises can be avoided or reduced by

A Automatic gain control B Amplifying C Filtering D None of the mentioned

✅ Correct Answer: 1

5 Timing jitter can be reduced by

A Good power supply isolation B Stable clock reference C Good power supply isolation & Stable clock reference D None of the mentioned

✅ Correct Answer: 3

6 The reasons for the threshold effect are

A Thermal noise B Interference from other users C Interference from circuit switching transients D All of the mentioned

✅ Correct Answer: 4

7 When channel bandwidth is greater than the pulse bandwidth, it causes

A Intersignal interference B Intersymbol interference C Bandwidth error D None of the mentioned

✅ Correct Answer: 2

8 The _____________ corresponds to average quantization noise power.

A Mean B Variance C Probability density function D None of the mentioned

✅ Correct Answer: 2

9 Signal to noise ratio increases as ___________ increases.

A Quantization level B Square of quantization level C Square root of quantization level D None of the mentioned

✅ Correct Answer: 2

10 Signal to noise ratio is infinite when

A Quantization noise is zero B Number of levels are infinite C Quantization noise is zero & Number of levels are infinite D None of the mentioned

✅ Correct Answer: 3

11 The length of the code-word obtained by encoding quantized sample is equal to

A l=log(to the base 2)L B l=log(to the base 10)L C l=2log(to the base 2)L D l=log(to the base 2)L/2

✅ Correct Answer: 1

12 Quantization noise can be reduced by ________ the number of levels.

A Decreasing B Increasing C Doubling D Squaring

✅ Correct Answer: 2

13 In PCM encoding, quantization level varies as a function of ________

A Frequency B Amplitude C Square of frequency D Square of amplitude

✅ Correct Answer: 2

14 What is bit depth?

A Number of quantization level B Interval between two quantization levels C Number of possible digital values to represent each sample D None of the mentioned

✅ Correct Answer: 3

15 Choosing a discrete value that is near but not exactly at the analog signal level leads to

A PCM error B Quantization error C PAM error D Sampling error

✅ Correct Answer: 2

16 In PCM the samples are dependent on ________

A Time B Frequency C Quanization leavel D Interval between quantization level

✅ Correct Answer: 1

17 DPCM encodes the PCM values based on

A Quantization level B Difference between the current and predicted value C Interval between levels D None of the mentioned

✅ Correct Answer: 2

18 Delta modulation uses _____ bits per sample.

A One B Two C Four D Eight

✅ Correct Answer: 1

19 Sample resolution for LPCM ____ bits per sample.

A 8 B 16 C 24 D All of the mentioned

✅ Correct Answer: 4

20 Adaptive DPCM is used to

A Increase bandwidth B Decrease bandwidth C Increase SNR D None of the mentioned

✅ Correct Answer: 2

21 The size of the quantile interval is called as

A Inter level B Step size C Quantile size D Level width

✅ Correct Answer: 2

22 Uniform quantization provides better quantization for

A Weak signals B Strong signals C Weak & Strong signals D None of the mentioned

✅ Correct Answer: 2

23 Non uniform quantization provides better quantization for

A Weak signals B Coarse signals C Weak & Coarse signals D None of the mentioned

✅ Correct Answer: 1

24 In non uniform quantization, the quantization noise is _______ to signal size.

A Inversely proportional B Directly proportional C Equal D Double

✅ Correct Answer: 2

25 The output SNR can be made independent of input signal level by using

A Uniform quantizer B Non uniform quantizer C Uniform & Non uniform quantizer D None of the mentioned

✅ Correct Answer: 2

26 Companding is the process of

A Compression B Expansion C Compression & Expansion D None of the mentioned

✅ Correct Answer: 3

27 Which value of Î¼ corresponds to linear amplification?

A Î¼=0 B Î¼=1 C Î¼>0 D Î¼<0

✅ Correct Answer: 1

28 What is the standard value of Î¼ in Î¼-law ?

A 128 B 255 C 256 D 0

✅ Correct Answer: 2

29 The standard value of A in A-law is

A 87 B 88 C 86.7 D 87.6

✅ Correct Answer: 4

30 Which type of quantization is most preferable for audio signals for a human ear?

A Uniform quantization B Non uniform quantization C Uniform & Non uniform quantization D None of the mentioned

✅ Correct Answer: 2

31 Which waveforms are also called as line codes?

A PCM B PAM C FM D AM

✅ Correct Answer: 1

32 When pulse code modulation is applied to non binary symbols we obtain waveform called as

A PCM B PAM C M-ary D line codes

✅ Correct Answer: 3

33 Examples of PCM waveforms are

A Non return to zero B Phase encoded C Multilevel binary D All of the mentioned

✅ Correct Answer: 4

34 Which type is used and preferred in digital logic circuits?

A NRZ-L B NRZ-M C NRZ-S D None of the mentioned

✅ Correct Answer: 1

35 Which method is called as differential encoding?

A NRZ-L B NRZ-M C NRZ-S D None of the mentioned

✅ Correct Answer: 2

36 Which method is preferred in magnetic tape recording?

A NRZ-L B NRZ-M C NRZ-S D None of the mentioned

✅ Correct Answer: 2

37 NRZ-S is complement of _______

A NRZ-L B NRZ-M C NRZ-L & NRZ-M D None of the mentioned

✅ Correct Answer: 2

38 The return to zero waveform consists of

A Unipolar RZ B Bipolar RZ C RZ-AMI D All of the mentioned

✅ Correct Answer: 4

39 Phase encoded group consists of

A Manchester coding B Bi-phase-mark C Miller coding D All of the mentioned

✅ Correct Answer: 4

40 In which waveform logic 1 is represented by half bit wide pulse and logic 0 is represented by absence of pulse?

A Unipolar RZ B Bipolar RZ C RZ-AMI D Manchester coding

✅ Correct Answer: 1

41 In which waveform logic 1 and logic 0 are represented by opposite one half bit wide pulses?

A Unipolar RZ B Bipolar RZ C RZ-AMI D Manchester coding

✅ Correct Answer: 2

42 In which waveform logic 1 is represented by equal amplitude alternating pulses?

A Unipolar RZ B Bipolar RZ C RZ-AMI D Manchester coding

✅ Correct Answer: 3

43 Application of phase encoded binary signals are

A Optical communication B Magnetic recording C Satellite telemetry D All of the mentioned

✅ Correct Answer: 4

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?

A Bi-p-L B Bi-p-M C Bi-p-S D Delay modulation

✅ Correct Answer: 1

45 Which binary waveform uses three levels?

A Bipolar RZ B RZ-AMI C Bipolar RZ & RZ-AMI D None of the mentioned

✅ Correct Answer: 3

46 Which waveform type has the feature of clocking?

A Manchester coding B Bbi-p-M C Delay modulation D NRZ-L

✅ Correct Answer: 1

47 Which waveform has the feature of error detection?

A NRZ-L B RZ-AMI C Manchester coding D Duobinary

✅ Correct Answer: 4

48 Which waveform scheme introduces bandwidth compression?

A Duobinary B Manchester coding C Phase encoded waveform D Multilevel codes

✅ Correct Answer: 4

49 Which waveform type has better noise immunity?

A NRZ B RZ C Phase encoded D Multilevel codes

✅ Correct Answer: 1

50 In pulse modulation, reciprocal of T(time) is

A Bandwidth B Symbol rate C Signal voltage D None of the mentioned

✅ Correct Answer: 2

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Digital Communications MCQs set-4