MCQOPTIONS
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MCQOPTIONS
This section includes 33 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. |
Channel’s phase response must be a linear function of |
| A. | Time |
| B. | Frequency |
| C. | Time & Frequency |
| D. | None of the mentioned |
| Answer» C. Time & Frequency | |
| 2. |
If the filter’s tap weight remains fixed during transmission of data, then the equalization is called as |
| A. | Preset equalization |
| B. | Adaptive equalization |
| C. | Fixed equalization |
| D. | None of the mentioned |
| Answer» B. Adaptive equalization | |
| 3. |
The detection method where carrier’s phase is given importance is called as |
| A. | Coherent detection |
| B. | Non coherent detection |
| C. | Coherent detection & Non coherent detection |
| D. | None of the mentioned |
| Answer» B. Non coherent detection | |
| 4. |
The disadvantage of preset equalizer is that |
| A. | It doesnot requires initial training pulse |
| B. | Time varying channel degrades the performance of the system |
| C. | All of the mentioned |
| D. | None of the mentioned |
| Answer» C. All of the mentioned | |
| 5. |
The sample from the demodulation process consists of sample which is _______ to energy of the received symbol and _____ to noise. |
| A. | Directly and inversely proportional |
| B. | Inversely and directly proportional |
| C. | Both directly proportional |
| D. | Both inversely proportional |
| Answer» B. Inversely and directly proportional | |
| 6. |
Range of time difference of the zero crossing gives the value of |
| A. | Width |
| B. | Distortion |
| C. | Timing jitter |
| D. | Noise margin |
| Answer» D. Noise margin | |
| 7. |
A Gaussian distribution into the non linear envelope detector yields |
| A. | Rayleigh distribution |
| B. | Normal distribution |
| C. | Poisson distribution |
| D. | Binary distribution |
| Answer» B. Normal distribution | |
| 8. |
The _______ of the opening of eye pattern indicates the time over which the sampling for detection might be performed. |
| A. | Length |
| B. | Width |
| C. | X-axis value |
| D. | Y-axis value |
| Answer» C. X-axis value | |
| 9. |
As the eye opens, ISI _______ |
| A. | Increases |
| B. | Decreases |
| C. | Remains the same |
| D. | None of the mentioned |
| Answer» C. Remains the same | |
| 10. |
If the filter's tap weight remains fixed during transmission of data, then the equalization is called as |
| A. | Preset equalization |
| B. | Adaptive equalization |
| C. | Fixed equalization |
| D. | None of the mentioned |
| Answer» B. Adaptive equalization | |
| 11. |
Examples of double side band signals are |
| A. | ASK |
| B. | PSK |
| C. | ASK & PSK |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 12. |
Pseudo noise signal has _______ and _______ SNR for the same peak transmitted power. |
| A. | Larger, smaller |
| B. | Smaller, larger |
| C. | Larger, larger |
| D. | Smaller, smaller |
| Answer» D. Smaller, smaller | |
| 13. |
Equalization method which is done by tracking a slowly time varying channel response is |
| A. | Preset equalization |
| B. | Adaptive equalization |
| C. | Variable equalization |
| D. | None of the mentioned |
| Answer» C. Variable equalization | |
| 14. |
Which is the main system consideration? |
| A. | Probability of error |
| B. | System complexity |
| C. | Random fading channel |
| D. | All of the mentioned |
| Answer» E. | |
| 15. |
Matched filter provides _____ signal to noise ratio. |
| A. | Maximum |
| B. | Minimum |
| C. | Zero |
| D. | Infinity |
| Answer» B. Minimum | |
| 16. |
The range of amplitude difference gives the value of |
| A. | Width |
| B. | Distortion |
| C. | Timing jitter |
| D. | Noise margin |
| Answer» C. Timing jitter | |
| 17. |
The index value n, in transversal filter can be used as. |
| A. | Time offset |
| B. | Filter coefficient identifier |
| C. | Time offset & Filter coefficient identifier |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 18. |
The non coherent FSK needs ________ Eb/N0 than coherent FSK. |
| A. | 1db more |
| B. | 1db less |
| C. | 3db more |
| D. | 3db less |
| Answer» B. 1db less | |
| 19. |
Channel's phase response must be a linear function of |
| A. | Time |
| B. | Frequency |
| C. | Time & Frequency |
| D. | None of the mentioned |
| Answer» C. Time & Frequency | |
| 20. |
A pulse shaping filter should satisfy two requirements. They are |
| A. | Should be realizable |
| B. | Should have proper roll off factor |
| C. | Should be realizable & have proper roll off factor |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 21. |
The channel may be affected by |
| A. | Thermal noise |
| B. | Interference from other signals |
| C. | Thermal noise & Interference from other signals |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 22. |
The DPSK needs ________ Eb/N0 than BPSK. |
| A. | 1db more |
| B. | 1db less |
| C. | 3db more |
| D. | 3db less |
| Answer» B. 1db less | |
| 23. |
For AWGN, the noise variance is |
| A. | N0 |
| B. | N0/2 |
| C. | 2N0 |
| D. | N0/4 |
| Answer» C. 2N0 | |
| 24. |
Which is easier to implement and is preferred? |
| A. | Coherent system |
| B. | Non coherent system |
| C. | Coherent & Non coherent system |
| D. | None of the mentioned |
| Answer» C. Coherent & Non coherent system | |
| 25. |
Coherent PSK and non coherent orthogonal FSK have a difference of ______ in PB. |
| A. | 1db |
| B. | 3db |
| C. | 4db |
| D. | 6db |
| Answer» D. 6db | |
| 26. |
Preamble is used for |
| A. | Detect start of transmission |
| B. | To set automatic gain control |
| C. | To align internal clocks |
| D. | All of the mentioned |
| Answer» E. | |
| 27. |
The average noise power of white noise is |
| A. | 0 |
| B. | Infinity |
| C. | 1 |
| D. | None of the mentioned |
| Answer» C. 1 | |
| 28. |
The impulse response of the filter is the ________ of the mirror image of the signal waveform. |
| A. | Delayed version |
| B. | Same version |
| C. | Delayed & Same version |
| D. | None of the mentioned |
| Answer» B. Same version | |
| 29. |
Channels display multi-path due to |
| A. | Scattering |
| B. | Time delayed reflections |
| C. | Diffraction |
| D. | All of the mentioned |
| Answer» E. | |
| 30. |
The over-determined set of equations can be solved using |
| A. | Zero forcing |
| B. | Minimum mean square error |
| C. | Zero forcing & Minimum mean square error |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 31. |
Performance of BFSK signal is ________ than BPSK. |
| A. | 3db worse |
| B. | 3db better |
| C. | 6db worse |
| D. | 6db better |
| Answer» B. 3db better | |
| 32. |
The likelihood ratio test is done between |
| A. | Likelihood of s1 by likelihood of s2 |
| B. | Likelihood of s2 by likelihood of s1 |
| C. | Likelihood of s1 by likelihood of s1 |
| D. | None of the mentioned |
| Answer» B. Likelihood of s2 by likelihood of s1 | |
| 33. |
Example for antipodal bandpass signaling is |
| A. | BPSK |
| B. | ASK |
| C. | FSK |
| D. | MSK |
| Answer» B. ASK | |