MCQOPTIONS
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MCQOPTIONS
This section includes 902 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
A signal xn is given by x0 = 3, x1 = 2, x2 = 5, x3 = 1, x4 = 0, x5 = 1, x6 = 2, x7 = 2, x8 = 4, where the subscript ‘n’ denotes time. The peak value of the auto correlation of x2n-11 is: |
| A. | 0 |
| B. | 10 |
| C. | 54 |
| D. | 64 |
| Answer» C. 54 | |
| 152. |
_____ are those signals whose values are completely specified for any given time. |
| A. | Deterministic signals |
| B. | Statistical signals |
| C. | Random signals |
| D. | Complex signals |
| Answer» B. Statistical signals | |
| 153. |
A discrete time signal is said to be a unit sample sequence if |
| A. | δ(n) = 1 for n = 0 = 0 for n ≠ 0 |
| B. | δ(n) = 2 for n = 0 = 0 for n ≠ 0 |
| C. | δ(n) = - 1 for n = 0 = 0 for n ≠ 0 |
| D. | δ(n) = - 2 for n = 0 = 0 for n ≠ 0 |
| Answer» B. δ(n) = 2 for n = 0 = 0 for n ≠ 0 | |
| 154. |
Let f(t) be a continuous-time signal and let F(ω) be its Fourier Transform defined by\(F\left( \omega \right) = \mathop \smallint \limits_{ - \infty }^\infty f\left( t \right){e^{ - j\omega t}}dt\)Define g(t) by\(g\left( t \right) = \mathop \smallint \limits_{ - \infty }^\infty F\left( u \right){e^{ - ju t}}du\)What is the relationship between f(t) and g(t)? |
| A. | g(t) would always be proportional to f(t) |
| B. | g(t) would be proportional to f(t) if f(t) is an even function |
| C. | g(t) would be proportional to f(t) only if f(t) is a sinusoidal function |
| D. | g(t) would never be proportional to f(t) |
| Answer» C. g(t) would be proportional to f(t) only if f(t) is a sinusoidal function | |
| 155. |
If a continuous-time signal x(t) = cos(2πt) is sampled at 4 Hz, the value of the discrete-time sequence x(n) at n = 5 is |
| A. | -0.707 |
| B. | -1 |
| C. | 0 |
| D. | 1 |
| Answer» D. 1 | |
| 156. |
Find the fundamental period of a discrete signal \(x\left[ n \right] = {e^{j\left( {\frac{\pi }{4}} \right)n}}\) |
| A. | 2 |
| B. | 4 |
| C. | 8 |
| D. | 6 |
| Answer» D. 6 | |
| 157. |
Consider y1(t) = x(3t) and y2(t) = x(t/3). Consider the following statements.1. If y1(t) and y2(t) are periodic, then x(t) is periodic.2. If x(t) is periodic, then y1(t) and y2(t) are periodic.Which of the above statements is/are true: |
| A. | None |
| B. | 1 |
| C. | 1 and 2 |
| D. | 2 |
| Answer» D. 2 | |
| 158. |
Find the fundamental period of a continuous-time sinusoidal signal x(t) = A cos (ω0t + θ). |
| A. | \({T_0} = \frac{{2\pi }}{{{\omega _0}}}\) |
| B. | T0 = 2π ω0 |
| C. | \({T_0} = \frac{{2\pi \theta }}{{{\omega _0}}}\) |
| D. | \({T_0} = \frac{{{\omega _0}}}{{2\pi }}\) |
| Answer» B. T0 = 2π ω0 | |
| 159. |
For the discrete-time system shown in the figure, the poles of the system transfer function are located at |
| A. | 2, 3 |
| B. | \(\frac{1}{2},3\) |
| C. | \(\frac{1}{2},\frac{1}{3}\) |
| D. | \(2,\frac{1}{3}\) |
| Answer» D. \(2,\frac{1}{3}\) | |
| 160. |
A discrete time signal x[n] = 2 sin(π2n), n being an integer, is |
| A. | periodic with period π |
| B. | periodic with period π2 |
| C. | periodic with period π/2 |
| D. | Not periodic |
| Answer» E. | |
| 161. |
Find out the fundamental period of discrete-time signal x(n) = (-1)n |
| A. | 2 |
| B. | 4 |
| C. | 6 |
| D. | 3 |
| Answer» B. 4 | |
| 162. |
A signal f(t) is described as\(f(t) = \begin{cases} [1-|t|] &{when~|t|\le1}\\ 0&{when~|t|>1} \end{cases}\)This represents the unit |
| A. | sinc function |
| B. | area triangular function |
| C. | signum function |
| D. | parabolic function |
| Answer» C. signum function | |
| 163. |
A discrete-time, Linear time-invariant system with input sequence xn and output sequence yn is characterized by:yn = 0.1 xn + 0.9 yn-1If two such systems are connected in series, which of the following is the governing differential equation of the overall system? |
| A. | yn – 1.8 yn-1 + 0.81 yn-2 = 0.01 xn |
| B. | yn + 0.81 yn-1 = 0.01 xn |
| C. | yn – 0.81 yn-1 + 1.8 yn-2 = 0.01 xn |
| D. | yn – 1.8 yn-I = 0.01 xn |
| Answer» B. yn + 0.81 yn-1 = 0.01 xn | |
| 164. |
An LTI system will be stable, if the impulse response h(t) has the restriction |
| A. | \(\mathop \smallint \limits_{ - \infty }^\infty \left| {h\left( \tau \right)d\tau } \right| < \infty \) |
| B. | \(\mathop \smallint \limits_{ - \infty }^\infty h\left( \tau \right).h\left( {t - \tau } \right)d\tau = 0\) |
| C. | y(t) = h(t).x(t) |
| D. | h(0) = 0 |
| Answer» B. \(\mathop \smallint \limits_{ - \infty }^\infty h\left( \tau \right).h\left( {t - \tau } \right)d\tau = 0\) | |
| 165. |
In a discrete-time complex exponential sequence of frequency ω0 = 1, the sequence is :1. Periodic with period \(\frac{2\pi}{\omega_0}\)2. Non-periodic3. Periodic for some value of period Nwhich of the above statements are correct? |
| A. | 1 only |
| B. | 2 only |
| C. | 3 only |
| D. | 1 and 3 |
| Answer» C. 3 only | |
| 166. |
During the transformation of the independent variable, if two signals identical in shape are displaced relative to each other, then the difference in propagation time from point of origin of transmitted signal results in |
| A. | Timeshift |
| B. | Time reversal |
| C. | Time scaling |
| D. | Time reduction |
| Answer» B. Time reversal | |
| 167. |
Fourier Transform of sgn(t) is _____, where sgn represents sigma function. |
| A. | jω |
| B. | 2jω |
| C. | jω/2 |
| D. | 2/jω |
| Answer» E. | |
| 168. |
A discrete delay system is defined as |
| A. | y(n) = x(n) |
| B. | y(n) = x (n + 1) |
| C. | y(n) = x (n – 1) |
| D. | y(n) = x(2n) |
| Answer» D. y(n) = x(2n) | |
| 169. |
Find the smallest angular frequency for which discrete-time sinusoidal signal with the following fundamental period N = 5 would be periodic. |
| A. | \({\rm{\Omega }} = \frac{\pi }{{10}}rad/cycle\) |
| B. | \({\rm{\Omega }} = \frac{{2\pi }}{5}rad/cycle\) |
| C. | \({\rm{\Omega }} = \frac{\pi }{5}rad/cycle\) |
| D. | \({\rm{\Omega }} = \frac{{2\pi }}{{15}}rad/cycle\) |
| Answer» C. \({\rm{\Omega }} = \frac{\pi }{5}rad/cycle\) | |
| 170. |
Consider an LTI system with impulse response h(t) = e-5t u(t). If the output of the system is y(t) = e-3t u(t) – e-5t u(t) then the input, x(t), is given by |
| A. | e-3t u(t) |
| B. | 2e-3t u(t) |
| C. | e-5t u(t) |
| D. | 2e-5t u(t) |
| Answer» C. e-5t u(t) | |
| 171. |
A signal x(t) with respect to time is sketched as under:The signal x(t) could be classified as: |
| A. | Exponentially increasing sinusoidal signal |
| B. | Real exponential decreasing signal |
| C. | Real exponential increasing signal |
| D. | Exponentially decreasing sinusoidal signal |
| Answer» B. Real exponential decreasing signal | |
| 172. |
Evaluate \(\frac{d}{{dt}}sgn\left( t \right).\) |
| A. | -2δ(t) |
| B. | 0 |
| C. | 2δ(t) |
| D. | δ(t) |
| Answer» D. δ(t) | |
| 173. |
Integral of unit impulse is a: |
| A. | Unit ramp |
| B. | Unit step |
| C. | Constant |
| D. | Unit impulse |
| Answer» C. Constant | |
| 174. |
A discrete-time all-pass system has two of its poles at 0.25∠0° and 2∠30°. Which one of the following statement about the system is TRUE? |
| A. | It has two more poles at 0.5∠30° and 4∠0°. |
| B. | It is stable only when the impulse response is two-sided. |
| C. | It has constant phase response over all frequencies. |
| D. | It has constant phase response over the entire z-plane. |
| Answer» C. It has constant phase response over all frequencies. | |
| 175. |
Consider the Signal x[n] = sin (2πn) u[n], where \(u\left[ n \right] = \left\{ {\begin{array}{*{20}{c}} {1\;\;n = 0,\;1,\;2,\;3,\; \ldots }\\ {0\;\;\;otherwise} \end{array}} \right.\)The period of the signal x[n] is |
| A. | 4 |
| B. | 3 |
| C. | 2 |
| D. | 1 |
| Answer» E. | |
| 176. |
Consider the waveform as shown in figure the correct representation of waveform is: |
| A. | s(t) = 2t u(t - 1) – 2tu(t) + 2u(t - 2) |
| B. | s(t) = 2(t - 1) u(t - 1) + 2(t - 2) u(t - 2) + 2u(t - 2) |
| C. | s(t) = 2t u(t - 1) + 2(t – 2) u(t - 2) – 2 u(t - 2) |
| D. | s(t) = 2(t – 1) u(t - 1) – 2(t - 2) u(t - 2) – 2 u(t - 2) |
| Answer» E. | |
| 177. |
Consider the system with following input-output relation\(y\left[ n \right] = \left[ {1 + {{\left( { - 1} \right)}^n}} \right]x\left[ n \right]\)where, x[n] is the input and y[n] is the output. The system is |
| A. | invertible and time invariant |
| B. | invertible and time varying |
| C. | non-invertible and time invariant |
| D. | non-invertible and time varying |
| Answer» E. | |
| 178. |
Evaluate \(\mathop \smallint \limits_{ - \infty }^\infty {e^{ - t}}\delta \left( {2t - 2} \right)dt\) |
| A. | 0 |
| B. | \(\frac{1}{{2e}}\) |
| C. | 1 |
| D. | \(\frac{1}{{e}}\) |
| Answer» C. 1 | |
| 179. |
Determine the fundamental period of the signal \(x(t)=\rm cos\ {\left( 2t+\frac{\pi}{4}\right)}\) |
| A. | π s |
| B. | 2π s |
| C. | \(\dfrac{\pi}{4}\ s\) |
| D. | \(\dfrac{\pi}{2}\ s\) |
| Answer» B. 2π s | |
| 180. |
Express the following finite discrete-time signal as the difference of two unit step sequences: x[n] = 1, for 0 ≤ n ≤ 5; and 0 otherwise. |
| A. | u[n] – u[n - 6] |
| B. | u[n - 5] – u[n - 6] |
| C. | u[n - 6] – u[n - 5] |
| D. | u[n] – u[n - 5] |
| Answer» B. u[n - 5] – u[n - 6] | |
| 181. |
A periodic function is given by a function that: |
| A. | is a period of T = 2π |
| B. | satisfies f(t + T) = f(t) |
| C. | satisfies f(T + t) = -f(t) |
| D. | is a period of T = π |
| Answer» C. satisfies f(T + t) = -f(t) | |
| 182. |
If x(-t) = x(t), x[-n] = x[n] then signals x(t) and x[n] are called as ______ |
| A. | non-periodic signal |
| B. | periodic signal |
| C. | odd signal |
| D. | even signal |
| Answer» E. | |
| 183. |
Consider a signal x(t) = 4 cos (2t/3) + 8 sin (0.5t) + 7 sin (t/3 – π/6)Calculate the fundamental periodic. |
| A. | 6π seconds |
| B. | 2π seconds |
| C. | 12π seconds |
| D. | π seconds |
| Answer» D. π seconds | |
| 184. |
If a system gives unbounded output for a bounded input, then the system is: |
| A. | Oscillatery |
| B. | Marginally |
| C. | Unstable |
| D. | Stable |
| Answer» D. Stable | |
| 185. |
Directions: It consists of two statements, one labeled as ‘Statement (I)’ and the other as ‘Statement (II)’. Examine these two statements carefully and select the answer using the code given below:Statement (I): FIR filters are always stable.Statement (II): IIR filters require less memory and are less complex. |
| A. | Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I) |
| B. | Both Statement (I) and Statement (II) are individually true but Statement (II) is not the correct explanation of Statement(I) |
| C. | Statement (I) is true but Statement (II) us false |
| D. | Statement (I) is false but Statement (II) is true |
| Answer» C. Statement (I) is true but Statement (II) us false | |
| 186. |
Consider the discrete time signal x(n) = {1, 1, 1, 1, 0.5, 0.5} ⋅ y(n) = conv (δ(n – 1), x(n)) is: |
| A. | 1 |
| B. | δ(n – 1) |
| C. | x(n – 1) |
| D. | 5 |
| Answer» D. 5 | |
| 187. |
Direction: Given question consists of two statements, one labeled as the 'Assertion (A)' and the other as 'Reason (R)'.You are to examine these two statements carefully and select the answers to these items using the codes given below.Assertion (A): The system function \(H(s) = \frac {z^3 - 2z^2 + z}{z^2 + \frac 1 4 z + \frac 18}\) is not causal.Reason (R): If the numerator of H(s) is of lower order than the denominator, the system may be causal. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is NOT the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are individually true but R is NOT the correct explanation of A | |
| 188. |
A signal x(t) follows the following property:x(t +T) = x(t) for all t, where T is a positive non zero value, The signal x(t) classified as: |
| A. | Periodic signal |
| B. | Rower signals |
| C. | complex signals |
| D. | Non-periodic signal |
| Answer» B. Rower signals | |
| 189. |
A system is defined by its input relationship y(t) = 2x(t + 2) + 2 where y(t) and x(t) are the output and the input of the system, respectively. The system is |
| A. | linear and causal |
| B. | linear and non-causal |
| C. | non-linear and causal |
| D. | non-linear and non-causal |
| Answer» E. | |
| 190. |
A triangular wave shape is obtained _________ |
| A. | by differentiating a sine wave |
| B. | by integrating a sine wave |
| C. | by integrating a square wave |
| D. | by differencing a square wave |
| Answer» D. by differencing a square wave | |
| 191. |
A continuous-time function x(t) is periodic with period T. The function is sampled uniformly with a sampling period |
| A. | \({\rm{T\;}} = {\rm{\;}}\sqrt 2 {\rm{\;Ts}}\) |
| B. | 𝑇 = 1.2 𝑇𝑠 |
| C. | Always |
| D. | Never |
| Answer» C. Always | |
| 192. |
A system is given by \(x\left( t \right) = {e^{at}}u\left( t \right)\). The system is |
| A. | Causal and Stable |
| B. | Non-causal and Stable |
| C. | Causal and Unstable |
| D. | Non-causal and Unstable |
| Answer» D. Non-causal and Unstable | |
| 193. |
Determine average power of the signal x(t) = cos(2πf0t)(where f0 is the fundamental frequency and ‘t’ indicates continuous-time domain) |
| A. | 1.0 W |
| B. | 2.0 W |
| C. | 10 W |
| D. | 0.5 W |
| Answer» E. | |
| 194. |
Only harmonics of the same frequency interact to produce: |
| A. | Average power |
| B. | Total power |
| C. | dc power |
| D. | ac power |
| Answer» B. Total power | |
| 195. |
A signal is represented by\(x\left( t \right) = \left\{ {\begin{array}{*{20}{c}}1&{\left| t \right|}&{ < 1}\\0&{\left| t \right|}&{ > 1}\end{array}} \right.\)The Fourier transform of the convolved signal y(t) = x(2t) * x(t/2) is |
| A. | \(\frac{4}{{{\omega ^2}}}\sin \left( {\frac{\omega }{2}} \right){\rm{sin}}\left( {2\omega } \right)\) |
| B. | \(\frac{4}{{{\omega ^2}}}\sin \left( {\frac{\omega }{2}} \right)\) |
| C. | \(\frac{4}{{{\omega ^2}}}\sin \left( {2\omega } \right)\) |
| D. | \(\frac{4}{{{\omega ^2}}}{\sin ^2}\omega\) |
| Answer» B. \(\frac{4}{{{\omega ^2}}}\sin \left( {\frac{\omega }{2}} \right)\) | |
| 196. |
Consider signal \(x\left( t \right) = \left\{ {\begin{array}{*{20}{c}} {1,}&{\left| t \right| \le 2}\\ {0,}&{\left| t \right| > 2} \end{array}} \right.\) Let |
| A. | 2 |
| B. | 1 |
| C. | 0 |
| D. | 3 |
| Answer» B. 1 | |
| 197. |
f(t) = -f(t-T/2)The given periodic function possesses: |
| A. | Half-wave symmetry |
| B. | Odd function symmetry |
| C. | Quarter wave symmetry |
| D. | Even function symmetry |
| Answer» B. Odd function symmetry | |
| 198. |
Find out even and odd part of signal x(t) = (2 + sin t)2 |
| A. | 4 + sin2t, 4 sin t |
| B. | 2 + sin2t, 2 sin t |
| C. | 4, 4 sin t + sin2 t |
| D. | 2, sin t |
| Answer» B. 2 + sin2t, 2 sin t | |
| 199. |
A unit ramp function when integrated yields: |
| A. | Unit parabolic function |
| B. | Unit ramp function |
| C. | Unit doublet |
| D. | Unit impulse function |
| Answer» B. Unit ramp function | |
| 200. |
Human voice is an example of: |
| A. | Analog Signal |
| B. | Digital signal |
| C. | Mixed Signal |
| D. | Periodic Signal |
| Answer» B. Digital signal | |