MCQOPTIONS
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MCQOPTIONS
This section includes 152 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. |
Due to transmission scheme bits are needed for overhead in FDMA systems. |
| A. | continuous, few |
| B. | discontinuous, few |
| C. | continuous, many |
| D. | discontinuous, many |
| Answer» B. discontinuous, few | |
| 2. |
Performance of BFSK signal is than BPSK. |
| A. | 3db worse |
| B. | 3db better |
| C. | 6db worse |
| D. | 6db better |
| Answer» B. 3db better | |
| 3. |
Power spectrum describes distribution of under frequency domain. |
| A. | mean |
| B. | variance |
| C. | gaussian |
| D. | none of the mentioned |
| Answer» C. gaussian | |
| 4. |
symbols. |
| A. | 2m |
| B. | m |
| C. | 2m |
| D. | 2m-1 |
| Answer» E. | |
| 5. |
In Binary Phase Shift Keying system, the binary symbols 1 and 0 arerepresented by carrier with phase shift of |
| A. | Π/2 |
| B. | Π |
| C. | 2Π |
| Answer» C. 2Π | |
| 6. |
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 | |
| 7. |
Autocorrelation is maximum at |
| A. | unity |
| B. | origin |
| C. | infinite point |
| D. | none of the mentioned |
| Answer» C. infinite point | |
| 8. |
In Random Variable we have |
| A. | sample space |
| B. | sample points |
| C. | sample space & sample points |
| D. | none of above |
| Answer» D. none of above | |
| 9. |
In On-Off keying, the carrier signal is transmitted with signal value‘1’ and ‘0’ indicates |
| A. | no carrier |
| B. | half the carrier amplitude |
| C. | amplitude of modulating signal |
| D. | none of the above |
| Answer» B. half the carrier amplitude | |
| 10. |
The digital modulation technique in which the step size is varied according to the variation in the slope of the input is called |
| A. | delta modulation |
| B. | pcm |
| C. | adaptive delta modulation |
| D. | pam |
| Answer» D. pam | |
| 11. |
The time interval over which the received signal may be sampledwithout error may be explained by |
| A. | width of eye opening of eye pattern |
| B. | rate of closure of eye of eye pattern |
| C. | height of the eye opening of eye pattern |
| D. | all of the above |
| Answer» B. rate of closure of eye of eye pattern | |
| 12. |
In the frequency of the carrier signal is varied based on the information in an a digital signal |
| A. | ask |
| B. | psk |
| C. | fsk |
| D. | qam |
| Answer» D. qam | |
| 13. |
Zero forced equalizers are used for |
| A. | reducing isi to zero |
| B. | sampling |
| C. | quantization |
| D. | none of the abov |
| Answer» B. sampling | |
| 14. |
Nyquist Rate is given by |
| A. | 2w |
| B. | 2fmin |
| Answer» B. 2fmin | |
| 15. |
In FH-SS which of the following Modulation Demodulation Technique has been used |
| A. | bpsk |
| B. | fsk |
| C. | ask |
| D. | qam |
| Answer» C. ask | |
| 16. |
What is the set of possible carrier frequencies in FH-SS? |
| A. | hopset |
| B. | hop |
| C. | chips |
| D. | symbols |
| Answer» B. hop | |
| 17. |
The number of bits of data transmitted per second is called |
| A. | data signaling rate |
| B. | modulation rate |
| C. | coding |
| D. | none of the above |
| Answer» B. modulation rate | |
| 18. |
White noise has power spectral density. |
| A. | constant |
| B. | variable |
| C. | constant & variable |
| D. | none of the mentioned |
| Answer» B. variable | |
| 19. |
The bandwidth of the channel used in the hopset is called |
| A. | hopping bandwidth |
| B. | total hopping bandwidth |
| C. | instantaneous bandwidth |
| D. | 3 db bandwidth |
| Answer» D. 3 db bandwidth | |
| 20. |
The advantage of using Manchester format of coding is |
| A. | power saving |
| B. | polarity sense at the receiver |
| C. | noise immunity |
| D. | none of the above |
| Answer» B. polarity sense at the receiver | |
| 21. |
In Differential Pulse Code Modulation techniques, the decoding is performed by |
| A. | accumulator |
| B. | sampler |
| C. | pll |
| D. | quantizer |
| Answer» B. sampler | |
| 22. |
In modulation , the bit rate is 8 times the baud rate |
| A. | 8-qam |
| B. | 64-qam |
| C. | 256-qam |
| D. | none of above |
| Answer» D. none of above | |
| 23. |
Eye pattern is |
| A. | is used to study isi |
| B. | may be seen on cro |
| C. | resembles the shape of human eye |
| D. | all of the above |
| Answer» E. | |
| 24. |
One of the disadvantages of PCM is |
| A. | it requires large bandwidth |
| B. | very high noise |
| C. | cannot be decoded easily |
| D. | all of the above |
| Answer» B. very high noise | |
| 25. |
Frequency division multiple access (FDMA) assigns channels to users. |
| A. | individual, individual |
| B. | many, individual |
| C. | individual, many |
| D. | many, many |
| Answer» B. many, individual | |
| 26. |
The maximum bandwidth is occupied by |
| A. | ask |
| B. | bpsk |
| C. | fsk |
| D. | none of the above |
| Answer» D. none of the above | |
| 27. |
Random process is a function of |
| A. | random event and time |
| B. | random event and frequency |
| C. | random event and real number |
| D. | none of the mentioned |
| Answer» B. random event and frequency | |
| 28. |
The process of coding multiplexer output into electrical pulses orwaveforms for transmission is called |
| A. | line coding |
| B. | amplitude modulation |
| C. | fsk |
| D. | filtering |
| Answer» B. amplitude modulation | |
| 29. |
The modulation techniques used to convert analog signal into digitalsignal are |
| A. | pulse code modulation |
| B. | delta modulation |
| C. | adaptive delta modulation |
| D. | all of the above |
| Answer» E. | |
| 30. |
The probability of error of DPSK is ______________ than that ofBPSK. |
| A. | higher |
| B. | lower |
| C. | same |
| D. | not predictable |
| Answer» B. lower | |
| 31. |
Pseudorandom signal predicted. |
| A. | can be |
| B. | cannot be |
| C. | maybe |
| D. | none of the mentioned |
| Answer» B. cannot be | |
| 32. |
ISI may be removed by using |
| A. | differential coding |
| B. | manchester coding |
| C. | polar nrz |
| D. | none of the above |
| Answer» B. manchester coding | |
| 33. |
QPSK system uses a phase shift of |
| A. | Π |
| B. | Π/2 |
| C. | Π/4 |
| D. | 2Π |
| Answer» C. Π/4 | |
| 34. |
For a noise to be white Gaussian noise, the optimum filter is known as |
| A. | low pass filter |
| B. | base band filter |
| C. | matched filter |
| D. | bessel filter |
| Answer» D. bessel filter | |
| 35. |
Advantages of using AMI |
| A. | needs least power as due to opposite polarity |
| B. | prevents build-up of dc |
| C. | may be used for longer distance |
| D. | all of the above |
| Answer» E. | |
| 36. |
In DS-SS which of the following Modulation Demodulation Technique has been used |
| A. | bpsk |
| B. | fsk |
| C. | ask |
| D. | qam |
| Answer» B. fsk | |
| 37. |
Impulse noise is caused due to |
| A. | switching transients |
| B. | lightening strikes |
| C. | power line load switching |
| D. | all of the above |
| Answer» E. | |
| 38. |
The BPSK signal has +V volts and -V volts respectively to represent |
| A. | 1 and 0 logic levels |
| B. | 11 and 00 logic levels |
| C. | 10 and 01 logic levels |
| D. | 00 and 11 logic levels |
| Answer» B. 11 and 00 logic levels | |
| 39. |
The noise that affects PCM |
| A. | transmission noise |
| B. | quantizing noise |
| C. | transit noise |
| D. | both a and b are correct |
| Answer» E. | |
| 40. |
Which of the following technique used in CDMA |
| A. | qam |
| B. | gmsk |
| C. | ds-ss bpsk |
| D. | fh-ss fsk |
| Answer» D. fh-ss fsk | |
| 41. |
The digital modulation technique in which the step size is variedaccording to the variation in the slope of the input is called |
| A. | delta modulation |
| B. | pcm |
| C. | adaptive delta modulation |
| D. | pam |
| Answer» D. pam | |
| 42. |
The sequence of operations in which PCM is done is |
| A. | sampling, quantizing, encoding |
| B. | quantizing, encoding, sampling |
| C. | quantizing, sampling, encoding |
| D. | none of the above |
| Answer» B. quantizing, encoding, sampling | |
| 43. |
The FDMA channel carries phone circuit at a time. |
| A. | ten |
| B. | two |
| C. | one |
| D. | several |
| Answer» D. several | |
| 44. |
PN sequence can be generated using . |
| A. | sequential logic circuits |
| B. | op-amp |
| C. | timer ic |
| D. | mosfet |
| Answer» B. op-amp | |
| 45. |
Minimum shift keying is similar to |
| A. | continuous phase frequency shift keying |
| B. | binary phase shift keying |
| C. | binary frequency shift keying |
| D. | qpsk |
| Answer» B. binary phase shift keying | |
| 46. |
The binary waveform used to generate BPSK signal is encoded in |
| A. | bipolar nrz format |
| B. | manchester coding |
| C. | differential coding |
| D. | none of the above |
| Answer» B. manchester coding | |
| 47. |
Impulse sampling is also called as |
| A. | delta sampling |
| B. | ideal sampling |
| C. | natural sampling |
| D. | both a & b |
| Answer» E. | |
| 48. |
The number of voice channels that can be accommodated for transmission in T1 carrier system is |
| A. | 24 |
| B. | 32 |
| C. | 56 |
| D. | 64 |
| Answer» B. 32 | |
| 49. |
In the amplitude of the carrier signal is varied based on the information in an a digital signal |
| A. | ask |
| B. | psk |
| C. | fsk |
| D. | qam |
| Answer» B. psk | |
| 50. |
Because of transmissions in TDMA, the handoff process in |
| A. | continuous, complex |
| B. | continuous, simple |
| C. | discontinuous, complex |
| D. | discontinuous, simple |
| Answer» E. | |