McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .
| 101. |
Alternate Mark Inversion (AMI) is also known as |
| A. | pseudo ternary coding |
| B. | manchester coding |
| C. | polar nrz format |
| D. | none of the above |
| Answer» A. pseudo ternary coding | |
| 102. |
The process of coding multiplexer output into electrical pulses or waveforms for transmission is called |
| A. | line coding |
| B. | amplitude modulation |
| C. | fsk |
| D. | filtering |
| Answer» A. line coding | |
| 103. |
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» D. all of the above | |
| 104. |
The criterion used for pulse shaping to avoid ISI is |
| A. | nyquist criterion |
| B. | quantization |
| C. | sample and hold |
| D. | pll |
| Answer» A. nyquist criterion | |
| 105. |
TDM is |
| A. | analog multiplexing |
| B. | digital multiplexing |
| C. | a to d converter |
| D. | both a & b |
| Answer» B. digital multiplexing | |
| 106. |
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» C. random event and a real number | |
| 107. |
The distribution function of random variable is |
| A. | p(x less than or equal to x) |
| B. | p(x greater than or equal to x) |
| C. | p(x less than x) |
| D. | p(x greater than x) |
| Answer» A. p(x less than or equal to x) | |
| 108. |
The value of the probability density function of random variable is |
| A. | positive function |
| B. | negative function |
| C. | zero |
| D. | one |
| Answer» A. positive function | |
| 109. |
Which gives the measure of randomness of the random variable? |
| A. | mean |
| B. | variance |
| C. | standard variance |
| D. | |
| Answer» B. variance | |
| 110. |
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» A. random event and time | |
| 111. |
A random process is called as stationary in strict sense if |
| A. | its statistics vary with shift in time origin |
| B. | its statistics does not vary with shift in time origin |
| C. | its autocorrelation vary with shift in time |
| D. | its autocorrelation does not vary with shift in time |
| Answer» A. its statistics vary with shift in time origin | |
| 112. |
For a stationary process, autocorrelation function depends on |
| A. | time |
| B. | time difference |
| C. | does not depend on time |
| D. | none of the mentioned |
| Answer» B. time difference | |
| 113. |
The autocorrelation function is maximum at |
| A. | origin |
| B. | infinity |
| C. | origin & infinity |
| D. | none of the mentioned |
| Answer» A. origin | |
| 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» B. rms value or ac | |
| 115. |
The average power of white noise is |
| A. | zero |
| B. | unity |
| C. | infinity |
| D. | between zero and one |
| Answer» C. infinity | |
| 116. |
he distribution function of -(infinity) and (infinity) is |
| A. | 0 and 1 |
| B. | 1 and 0 |
| C. | both 0 |
| D. | both 1 |
| Answer» A. 0 and 1 | |
| 117. |
White noise has mean and _ variance. |
| A. | zero and zero |
| B. | finite and zero |
| C. | zero and finite |
| D. | one and zero |
| Answer» C. zero and finite | |
| 118. |
Power spectral density function is a? |
| A. | real and even function |
| B. | non negative function |
| C. | periodic |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 119. |
Energy spectral density defines |
| A. | signal energy per unit area |
| B. | signal energy per unit bandwidth |
| C. | signal power per unit area |
| D. | signal power per unit bandwidth |
| Answer» B. signal energy per unit bandwidth | |
| 120. |
Power spectrum describes distribution of under frequency domain. |
| A. | mean |
| B. | variance |
| C. | gaussian |
| D. | none of the mentioned |
| Answer» B. variance | |
| 121. |
How can power spectral density of non periodic signal be calculated? |
| A. | by integrating |
| B. | by truncating |
| C. | by converting to periodic |
| D. | none of the mentioned |
| Answer» B. by truncating | |
| 122. |
What is Wiener-Khinchin theorem? |
| A. | spectral density and auto-covariance makes a fourier transform pair |
| B. | spectral density and auto-correlatioon makes a fourier transform pair |
| C. | spectral density and variance makes a fourier transform pair |
| D. | none of the mentioned |
| Answer» B. spectral density and auto-correlatioon makes a fourier transform pair | |
| 123. |
According to Parseval’s theorem the energy spectral density curve is equal to? |
| A. | area under magnitude of the signal |
| B. | area under square of the magnitude of the signal |
| C. | area under square root of magnitude of the signal |
| D. | none of the mentioned |
| Answer» B. area under square of the magnitude of the signal | |
| 124. |
Autocorrelation is a function which matches |
| A. | two same signals |
| B. | two different signal |
| C. | one signal with its delayed version |
| D. | none of the mentioned |
| Answer» C. one signal with its delayed version | |
| 125. |
Autocorrelation is a function of |
| A. | time |
| B. | frequency |
| C. | time difference |
| D. | frequency difference |
| Answer» C. time difference | |
| 126. |
Autocorrelation is maximum at |
| A. | unity |
| B. | origin |
| C. | infinite point |
| D. | none of the mentioned |
| Answer» B. origin | |
| 127. |
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» B. power of the signal | |
| 128. |
Autocorrelation function of white noise will have? |
| A. | strong peak |
| B. | infinite peak |
| C. | weak peak |
| D. | none of the mentioned |
| Answer» A. strong peak | |
| 129. |
Thermal noise in the communication system due to thermal electrons |
| A. | can be eliminated |
| B. | cannot be eliminated |
| C. | can be avoided upto some extent |
| D. | none of the mentioned |
| Answer» B. cannot be eliminated | |
| 130. |
White noise has power spectral density. |
| A. | constant |
| B. | variable |
| C. | constant & variable |
| D. | none of the mentioned |
| Answer» A. constant | |
| 131. |
The average noise power of white noise is |
| A. | 0 |
| B. | infinity |
| C. | 1 |
| D. | none of the mentioned |
| Answer» B. infinity | |
| 132. |
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» C. thermal noise & interference from other signals | |
| 133. |
In Random Variable we have |
| A. | sample space |
| B. | sample points |
| C. | sample space & sample points |
| D. | none of above |
| Answer» C. sample space & sample points | |
| 134. |
In Random Process we have |
| A. | sample function |
| B. | ensemble of sample function |
| C. | sample space & sample points |
| D. | sample function & ensemble of sample function |
| Answer» D. sample function & ensemble of sample function | |
| 135. |
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» A. coherent detection | |
| 136. |
The coherent modulation techniques are |
| A. | psk |
| B. | fsk |
| C. | ask |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 137. |
The real part of a sinusoid carrier wave is called as |
| A. | inphase |
| B. | quadrature |
| C. | inphase & quadrature |
| D. | none of the mentioned |
| Answer» A. inphase | |
| 138. |
The FSK signal which has a gentle shift from one frequency level to another is called as |
| A. | differential psk |
| B. | continuous psk |
| C. | differential & continuous psk |
| D. | none of the mentioned |
| Answer» B. continuous psk | |
| 139. |
Which modulation scheme is also called as on-off keying method? |
| A. | ask |
| B. | fsk |
| C. | psk |
| D. | gmsk |
| Answer» A. ask | |
| 140. |
In differential PSK the date is |
| A. | encoded differentially |
| B. | decoded differentially |
| C. | encoded & decoded differentially |
| D. | none of the mentioned |
| Answer» A. encoded differentially | |
| 141. |
Envelope detector consists of |
| A. | rectifier and high pass filter |
| B. | rectifier and low pass filter |
| C. | amplifier and low pass filter |
| D. | amplifier and high pass filter |
| Answer» B. rectifier and low pass filter | |
| 142. |
M-ary signaling produces error performance with orthogonal signaling and error performance with multiple phase signalling. |
| A. | degraded, improved |
| B. | improved, degraded |
| C. | improved, improved |
| D. | degraded, degraded |
| Answer» B. improved, degraded | |
| 143. |
Which is more vulnerable to noise? |
| A. | 2-ary system |
| B. | 4-ary system |
| C. | binary system |
| D. | none of the mentioned |
| Answer» B. 4-ary system | |
| 144. |
In which system, bit stream is portioned into even and odd stream? |
| A. | bpsk |
| B. | msk |
| C. | qpsk |
| D. | fsk |
| Answer» C. qpsk | |
| 145. |
The error performance of MPSK as M or k increases. |
| A. | increases |
| B. | decreases |
| C. | stays constant |
| D. | none of the mentioned |
| Answer» B. decreases | |
| 146. |
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» A. does, does not | |
| 147. |
In orthogonal signalling with symbols containing more number of bits we need power. |
| A. | more |
| B. | less |
| C. | double |
| D. | none of the mentioned |
| Answer» A. more | |
| 148. |
Energy per symbol Es is given as |
| A. | es=eb(log2m) |
| B. | es=eb/(log2m) |
| C. | es=2eb(log2m) |
| D. | es=eb/2(log2m) |
| Answer» A. es=eb(log2m) | |
| 149. |
The relation between the probability of bit error and probability of symbol error in M-ary orthogonal signalling is |
| A. | m/m-1 |
| B. | 2m/m-1 |
| C. | (m/2)/m-1 |
| D. | m/m+1 |
| Answer» C. (m/2)/m-1 | |
| 150. |
Performance of BFSK signal is than BPSK. |
| A. | 3db worse |
| B. | 3db better |
| C. | 6db worse |
| D. | 6db better |
| Answer» A. 3db worse | |
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