MCQOPTIONS
Saved Bookmarks
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.
| 101. |
In MPSK adding new signals make it vulnerable to noise and in MFSK make it vulnerable. |
| A. | does, does not |
| B. | does not, does |
| C. | does, does |
| D. | does not, does not |
| Answer» B. does not, does | |
| 102. |
The number of voice channels that can be accommodated fortransmission in T1 carrier system is |
| A. | 24 |
| B. | 32 |
| C. | 56 |
| D. | 64 |
| Answer» B. 32 | |
| 103. |
The maximum data transmission rate in T1 carrier system is |
| A. | 2.6 megabits per second |
| B. | 1000 megabits per second |
| C. | 1.544 megabits per second |
| D. | 5.6 megabits per second |
| Answer» D. 5.6 megabits per second | |
| 104. |
The preferred orthogonalization process for its numerical stability is |
| A. | gram- schmidt process |
| B. | house holder transformation |
| C. | optimization |
| D. | all of the above |
| Answer» C. optimization | |
| 105. |
In Binary FSK, mark and space respectively represent |
| A. | 1 and 0 |
| B. | 0 and 1 |
| C. | 11 and 00 |
| D. | 00 and 11 |
| Answer» B. 0 and 1 | |
| 106. |
Scrambling of data is |
| A. | removing long strings of 1’s and 0’s |
| B. | exchanging of data |
| C. | transmission of digital data |
| D. | all of the above |
| Answer» B. exchanging of data | |
| 107. |
Roll – off factor is defined as |
| A. | the bandwidth occupied beyond the nyquist bandwidth of the filter |
| B. | the performance of the filter or device |
| C. | aliasing effect |
| D. | none of the above |
| Answer» B. the performance of the filter or device | |
| 108. |
In digital transmission, the modulation technique that requiresminimum bandwidth is |
| A. | delta modulation |
| B. | pcm |
| C. | dpcm |
| D. | pam |
| Answer» B. pcm | |
| 109. |
The bandwidth of BFSK is ______________ than BPSK. |
| A. | lower |
| B. | same |
| C. | higher |
| D. | not predictable |
| Answer» D. not predictable | |
| 110. |
Equalization in digital communication |
| A. | reduces inter symbol interference |
| B. | removes distortion caused due to channel |
| C. | is done using linear filters |
| D. | all of the above |
| Answer» E. | |
| 111. |
The factors that cause quantizing error in delta modulation are |
| A. | slope overload distortion |
| B. | granular noise |
| C. | white noise |
| D. | both a and b are correct |
| Answer» E. | |
| 112. |
Matched filter may be optimally used only for |
| A. | gaussian noise |
| B. | transit time noise |
| C. | flicker |
| D. | all of the above |
| Answer» B. transit time noise | |
| 113. |
The data rate of QPSK is ___________ of BPSK. |
| A. | thrice |
| B. | four times |
| C. | twice |
| D. | same |
| Answer» D. same | |
| 114. |
Standard deviation is _ |
| A. | rms value of dc |
| B. | rms value or ac |
| C. | either ac or dc |
| D. | neither dc nor ac |
| Answer» C. either ac or dc | |
| 115. |
Coherent detection of binary ASK signal requires |
| A. | phase synchronization |
| B. | timing synchronization |
| C. | amplitude synchronization |
| D. | both a and b |
| Answer» E. | |
| 116. |
Autocorrelation function of periodic signal is equal to |
| A. | energy of the signal |
| B. | power of the signal |
| C. | its area in frequency domain |
| D. | none of the mentioned |
| Answer» C. its area in frequency domain | |
| 117. |
In Adaptive Delta Modulation, the slope error reduces and |
| A. | quantization error decreases |
| B. | quantization error increases |
| C. | quantization error remains same |
| D. | none of the above |
| Answer» C. quantization error remains same | |
| 118. |
he distribution function of -(infinity) and (infinity) is |
| A. | 0 and 1 |
| B. | 1 and 0 |
| C. | both 0 |
| D. | both 1 |
| Answer» B. 1 and 0 | |
| 119. |
DPCM suffers from |
| A. | slope over load distortion |
| B. | quantization noise |
| C. | both a & b |
| D. | none of the above |
| Answer» D. none of the above | |
| 120. |
Orthonormal set is a set of all vectors that are |
| A. | mutually orthonormal and are of unit length |
| B. | mutually orthonormal and of null length |
| C. | both a & b |
| D. | none of the above |
| Answer» B. mutually orthonormal and of null length | |
| 121. |
Synchronization of signals is done using |
| A. | pilot clock |
| B. | extracting timing information from the received signal |
| C. | transmitter and receiver connected to master timing source |
| D. | all of the above |
| Answer» E. | |
| 122. |
For a line code, the transmission bandwidth must be |
| A. | maximum possible |
| B. | as small as possible |
| C. | depends on the signal |
| D. | none of the above |
| Answer» C. depends on the signal | |
| 123. |
Matched filters may be used |
| A. | to estimate the frequency of the received signal |
| B. | in parameter estimation problems |
| C. | to estimate the distance of the object |
| D. | all of the above |
| Answer» E. | |
| 124. |
Granular noise occurs when |
| A. | step size is too small |
| B. | step size is too large |
| C. | there is interference from the adjacent channel |
| D. | bandwidth is too large |
| Answer» C. there is interference from the adjacent channel | |
| 125. |
Pulse shaping is done |
| A. | to control inter symbol interference |
| B. | by limiting the bandwidth of transmission |
| C. | after line coding and modulation of signal |
| D. | all of the above |
| Answer» E. | |
| 126. |
White noise has mean and _ variance. |
| A. | zero and zero |
| B. | finite and zero |
| C. | zero and finite |
| D. | one and zero |
| Answer» D. one and zero | |
| 127. |
The interference caused by the adjacent pulses in digital transmissionis called |
| A. | inter symbol interference |
| B. | white noise |
| C. | image frequency interference |
| D. | transit time noise |
| Answer» B. white noise | |
| 128. |
The spectrum of BFSK may be viewed as the sum of |
| A. | two ask spectra |
| B. | two psk spectra |
| C. | two fsk spectra |
| D. | none of the above |
| Answer» B. two psk spectra | |
| 129. |
For two vectors to be orthonormal, the vectors are also said to beorthogonal. The reverse of the same |
| A. | is true |
| B. | is not true |
| C. | is not predictable |
| D. | none of the above |
| Answer» C. is not predictable | |
| 130. |
The criterion used for pulse shaping to avoid ISI is |
| A. | nyquist criterion |
| B. | quantization |
| C. | sample and hold |
| D. | pll |
| Answer» B. quantization | |
| 131. |
The DPSK needs Eb/N0 than BPSK. |
| A. | 1db more |
| B. | 1db less |
| C. | 3db more |
| D. | 3db less |
| Answer» B. 1db less | |
| 132. |
In coherent detection of signals, |
| A. | local carrier is generated |
| B. | carrier of frequency and phase as same as transmitted carrier is generated |
| C. | the carrier is in synchronization with modulated carrier |
| D. | all of the above |
| Answer» E. | |
| 133. |
Probability density function defines |
| A. | amplitudes of random noise |
| B. | density of signal |
| C. | probability of error |
| D. | all of the above |
| Answer» B. density of signal | |
| 134. |
Random variables give relationship between _ |
| A. | two random events |
| B. | probability of occurrence of two random events |
| C. | random event and a real number |
| D. | random event and its probability of occurrence |
| Answer» D. random event and its probability of occurrence | |
| 135. |
The process of converting the analog sample into discrete form is called |
| A. | modulation |
| B. | multiplexing |
| C. | quantization |
| D. | sampling |
| Answer» D. sampling | |
| 136. |
Analog to digital conversion includes |
| A. | Sampling |
| B. | Quantization |
| C. | Sampling & Quantization |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 137. |
Digital system includes |
| A. | Better encryption algorithm |
| B. | Difficult data multiplexing |
| C. | All of the mentioned |
| D. | None of the mentioned |
| Answer» B. Difficult data multiplexing | |
| 138. |
Synchronization available in digital communication are |
| A. | Symbol synchronization |
| B. | Frame synchronization |
| C. | Carrier synchronization |
| D. | All of the mentioned |
| Answer» E. | |
| 139. |
The attenuation level in bounded power spectral density is |
| A. | 35 |
| B. | 50 |
| C. | 35 & 50 |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 140. |
Effective radiated power of an isotropic radiator can be given as a product of |
| A. | Radiated power and received power |
| B. | Effective area and physical area |
| C. | Transmitted power and transmitting gain |
| D. | Receiving power and receiving gain |
| Answer» D. Receiving power and receiving gain | |
| 141. |
Antenna’s efficiency is given by the ratio of |
| A. | Effective aperture to physical aperture |
| B. | Physical aperture to effective aperture |
| C. | Signal power to noise power |
| D. | Losses |
| Answer» B. Physical aperture to effective aperture | |
| 142. |
SYNCHRONIZATION_AVAILABLE_IN_DIGITAL_COMMUNICATION_ARE?$ |
| A. | Symbol synchronization |
| B. | Frame synchronization |
| C. | Carrier synchronization |
| D. | All of the mentioned |
| Answer» E. | |
| 143. |
Analog to digital conversion includes$ |
| A. | Sampling |
| B. | Quantization |
| C. | Sampling & Quantization |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 144. |
Digital_system_includes$ |
| A. | Better encryption algorithm |
| B. | Difficult data multiplexing |
| C. | All of the mentioned |
| D. | None of the mentioned |
| Answer» B. Difficult data multiplexing | |
| 145. |
The attenuation level in bounded power spectral density i? |
| A. | 35 |
| B. | 50 |
| C. | 35 & 50 |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 146. |
The interval of frequencies outside which the spectrum is zero is called as ________ |
| A. | null to null bandwidth |
| B. | normalized bandwidth |
| C. | absolute bandwidth |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 147. |
Which system uses digital transmission? |
| A. | ISDN |
| B. | LANs |
| C. | ISDN & LANs |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 148. |
Examples of digital communication are |
| A. | ISDN |
| B. | Modems |
| C. | Classical telephony |
| D. | All of the mentioned |
| Answer» E. | |
| 149. |
What are the disadvantages of digital communication? |
| A. | Needs more bandwidth |
| B. | Is more complex |
| C. | Needs more bandwidth & Is more complex |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 150. |
What is necessary for digital communication? |
| A. | Precision timing |
| B. | Frame synchronization |
| C. | Character synchronization |
| D. | All of the mentioned |
| Answer» E. | |