MCQOPTIONS
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MCQOPTIONS
This section includes 36 Mcqs, each offering curated multiple-choice questions to sharpen your Digital Communications knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The signal can be reconstructed |
| A. | At Nyquist rate |
| B. | Above Nyquist rate |
| C. | At & above the Nyquist rate |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 2. |
Which filter does not have sharp output? |
| A. | Linear phase filter |
| B. | Delayed symmetric filter |
| C. | Linear phase & Delayed symmetric filter |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 3. |
Original signal came to be retraced from sampled version using |
| A. | Low pass filtering |
| B. | High pass filtering |
| C. | Low & High pass filtering |
| D. | None of the mentioned |
| Answer» B. High pass filtering | |
| 4. |
In pulse modulation, reciprocal of T(time) is |
| A. | Bandwidth |
| B. | Symbol rate |
| C. | Signal voltage |
| D. | None of the mentioned |
| Answer» C. Signal voltage | |
| 5. |
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 |
| Answer» B. Bipolar RZ | |
| 6. |
Transmitted pulse becomes distorted due to |
| A. | Ideal transmission characteristic |
| B. | Non ideal transmission characteristic |
| C. | All of the mentioned |
| D. | None of the mentioned |
| Answer» C. All of the mentioned | |
| 7. |
Some of the M-ary waveforms are |
| A. | PAM |
| B. | PPM |
| C. | PDM |
| D. | All of the mentioned |
| Answer» E. | |
| 8. |
The _____________ corresponds to average quantization noise power. |
| A. | Mean |
| B. | Variance |
| C. | Probability density function |
| D. | None of the mentioned |
| Answer» C. Probability density function | |
| 9. |
Non uniform quantization provides better quantization for |
| A. | Weak signals |
| B. | Coarse signals |
| C. | Weak & Coarse signals |
| D. | None of the mentioned |
| Answer» B. Coarse signals | |
| 10. |
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 |
| Answer» C. Interval between levels | |
| 11. |
In which mixing is easier? |
| A. | Analog signal |
| B. | Digital signal |
| C. | Analog & Digital signal |
| D. | None of the mentioned |
| Answer» C. Analog & Digital signal | |
| 12. |
The ratio of average signal power and quantization noise is |
| A. | 3L2 |
| B. | L2/3 |
| C. | 2L3 |
| D. | L3/2 |
| Answer» B. L2/3 | |
| 13. |
The primary advantage of this method is |
| A. | redistribution of spectral density |
| B. | to favor low frequencies |
| C. | redistribution of spectral density & to favor low frequencies |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 14. |
Different cases of sampling include |
| A. | Ideal impulse sampling |
| B. | Flat-topped sampling |
| C. | Sampling with rectangular pulses |
| D. | All of the mentioned |
| Answer» E. | |
| 15. |
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 |
| Answer» D. None of the mentioned | |
| 16. |
Which device is needed for the reconstruction of signal? |
| A. | Low pass filter |
| B. | Equalizer |
| C. | Low pass filter & Equalizer |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 17. |
PCM word size can be described by |
| A. | Time period |
| B. | Symbol rate |
| C. | Number of quantization levels |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 18. |
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 |
| Answer» C. RZ-AMI | |
| 19. |
The return to zero waveform consists of |
| A. | Unipolar RZ |
| B. | Bipolar RZ |
| C. | RZ-AMI |
| D. | All of the mentioned |
| Answer» E. | |
| 20. |
In polybinary signalling method the present bit of binary sequence is algebraically added with ______ number of previous bits. |
| A. | j |
| B. | 2j |
| C. | j+2 |
| D. | j-2 |
| Answer» E. | |
| 21. |
Which method should be implemented for reducing bandwidth? |
| A. | Multilevel codes |
| B. | Multilevel signalling |
| C. | PAM |
| D. | PDM |
| Answer» C. PAM | |
| 22. |
Sample resolution for LPCM ____ bits per sample. |
| A. | 8 |
| B. | 16 |
| C. | 24 |
| D. | All of the mentioned |
| Answer» E. | |
| 23. |
Adaptive DPCM is used to |
| A. | Increase bandwidth |
| B. | Decrease bandwidth |
| C. | Increase SNR |
| D. | None of the mentioned |
| Answer» C. Increase SNR | |
| 24. |
Delta modulation uses _____ bits per sample. |
| A. | One |
| B. | Two |
| C. | Four |
| D. | Eight |
| Answer» B. Two | |
| 25. |
The size of the quantile interval is called as |
| A. | Inter level |
| B. | Step size |
| C. | Quantile size |
| D. | Level width |
| Answer» C. Quantile size | |
| 26. |
Multiplication of input signal with pulse train is done in ________ sampling. |
| A. | Impulse sampling |
| B. | Natural sampling |
| C. | Flat top sampling |
| D. | None of the mentioned |
| Answer» C. Flat top sampling | |
| 27. |
Which value of μ corresponds to linear amplification? |
| A. | μ=0 |
| B. | μ=1 |
| C. | μ>0 |
| D. | μ<0 |
| Answer» B. μ=1 | |
| 28. |
Phase encoded group consists of |
| A. | Manchester coding |
| B. | Bi-phase-mark |
| C. | Miller coding |
| D. | All of the mentioned |
| Answer» E. | |
| 29. |
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 |
| Answer» C. Uniform & Non uniform quantization | |
| 30. |
The standard value of A in A-law is |
| A. | 87 |
| B. | 88 |
| C. | 86.7 |
| D. | 87.6 |
| Answer» E. | |
| 31. |
Source encoding procedure does |
| A. | Sampling |
| B. | Quantization |
| C. | Compression |
| D. | All of the mentioned |
| Answer» E. | |
| 32. |
Flat top sampling or practical sampling has |
| A. | Same frequency |
| B. | Same amplitude |
| C. | Same time difference |
| D. | None of the mentioned |
| Answer» C. Same time difference | |
| 33. |
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 |
| Answer» C. Square root of quantization level | |
| 34. |
Decreasing the data rate is called as |
| A. | Aliasing |
| B. | Down sampling |
| C. | Up sampling |
| D. | None of the mentioned |
| Answer» C. Up sampling | |
| 35. |
Application of phase encoded binary signals are |
| A. | Optical communication |
| B. | Magnetic recording |
| C. | Satellite telemetry |
| D. | All of the mentioned |
| Answer» E. | |
| 36. |
What is the standard value of μ in μ-law ? |
| A. | 128 |
| B. | 255 |
| C. | 256 |
| D. | 0 |
| Answer» C. 256 | |