1) Which
mathematical notation specifies the condition of periodicity for a continuous time signal?
a. x(t)
= x(t +T0) b. x(n) = x(n+ N) c. x(t) = eαt d. None of the above


2) Which
property of delta function indicates the equality between the area under the product of function with shifted impulse and the value of function located at unit impulse instant?
a.
Replication b. Sampling c. Scaling d. Product


3) Which
among the below specified conditions/cases of discrete time in terms of real constant ‘a’, represents the doublesided decaying exponential signal?
a. a
> 1 b. 0 < a < 1 c. a < 1 d. 1 < a < 0


4) Damped
sinusoids are _____
a.
sinusoid signals multiplied by growing exponentials b. sinusoid signals divided by growing exponentials c. sinusoid signals multiplied by decaying exponentials d. sinusoid signals divided by decaying exponentials


5) An
amplitude of sinc function that passes through zero at multiple values of an independent variable ‘x’ ______
a.
Decreases with an increase in the magnitude of an independent variable (x) b. Increases with an increase in the magnitude of an independent variable (x) c. Always remains constant irrespective of variation in magnitude of ‘x’ d. Cannot be defined


6) A
system is said to be shift invariant only if______
a. a
shift in the input signal also results in the corresponding shift in the output b. a shift in the input signal does not exhibit the corresponding shift in the output c. a shifting level does not vary in an input as well as output d. a shifting at input does not affect the output


7) Which
condition determines the causality of the LTI system in terms of its impulse response?
a. Only
if the value of an impulse response is zero for all negative values of time b. Only if the value of an impulse response is unity for all negative values of time c. Only if the value of an impulse response is infinity for all negative values of time d. Only if the value of an impulse response is negative for all negative values of time


8) Under
which conditions does an initially relaxed system become unstable?
a. only
if bounded input generates unbounded output b. only if bounded input generates bounded output c. only if unbounded input generates unbounded output d. only if unbounded input generates bounded output


9) Which
among the following are the stable discrete time systems? 1. y(n) = x(4n)
a. 1
& 3 b. 2 & 4 c. 1, 3 & 4 d. 1, 2, 3 & 4


10) An
equalizer used to compensate the distortion in the communication system by faithful recovery of an original signal is nothing but an illustration of _________
a.
Static system b. Dynamic system c. Invertible system d. None of the above


11) Which
block of the discrete time systems requires memory in order to store the previous input?
a.
Adder b. Signal Multiplier c. Unit Delay d. Unit Advance


12) Which
type/s of discretetime system do/does not exhibit the necessity of any feedback?
a.
Recursive Systems b. Nonrecursive Systems c. Both a & b d. None of the above


13) Which
among the following belongs to the category of nonrecursive systems?
a.
Causal FIR Systems b. Noncausal FIR Systems c. Causal IIR Systems d. Noncausal IIR Systems


14) Recursive
Systems are basically characterized by the dependency of its output on _______
a.
Present input b. Past input c. Previous outputs d. All of the above


15) What
does the term y(1) indicate especially in an equation that represents the behaviour of the causal system?
a.
initial condition of the system b. negative initial condition of the system c. negative feedback condition of the system d. response of the system to its initial input


16) Which
type of system response to its input represents the zero value of its initial condition?
a. Zero
state response b. Zero input response c. Total response d. Natural response


17) Which
is/are the essential condition/s to get satisfied for a recursive system to be linear?
a. Zero
state response should be linear b. Principle of Superposition should be applicable to zero input response c. Total Response of the system should be addition of zero state & zero input responses d. All of the above


18) Which
among the following operations is/are not involved /associated with the computation process of linear convolution?
a.
Folding Operation b. Shifting Operation c. Multiplication Operation d. Integration Operation


19) A LTI
system is said to be initially relaxed system only if ____
a. Zero
input produces zero output b. Zero input produces nonzero output c. Zero input produces an output equal to unity d. None of the above


20) What
are the number of samples present in an impulse response called as?
a.
string b. array c. length d. element


21) Which
are the only waves that correspond/ support the measurement of phase angle in the line spectra?
a. Sine
waves b. Cosine waves c. Triangular waves d. Square waves


22) Doublesided
phase & amplitude spectra _____
a.
Possess an odd & even symmetry respectively b. Possess an even & odd symmetry respectively c. Both possess an odd symmetry d. Both possess an even symmetry


23) What
does the first term ‘a0’ in the below stated expression of a line spectrum indicate? x(t) = a0 + a1 cos w0 t + a2 cos2
a. DC
component b. Fundamental component c. Second harmonic component d. All of the above


24) Which
kind of frequency spectrum/spectra is/are obtained from the line spectrum of a continuous signal on the basis of Polar Fourier Series Method?
a.
Continuous in nature b. Discrete in nature c. Sampled in nature d. All of the above


25) Which
type/s of Fourier Series allow/s to represent the negative frequencies by plotting the doublesided spectrum for the analysis of periodic signals?
a.
Trigonometric Fourier Series b. Polar Fourier Series c. Exponential Fourier Series d. All of the above


26) What
does the signalling rate in the digital communication system imply?
a.
Number of digital pulses transmitted per second b. Number of digital pulses transmitted per minute c. Number of digital pulses received per second d. Number of digital pulses received per minute


27) As
the signalling rate increases, _______
a.
Width of each pulse increases b. Width of each pulse decreases c. Width of each pulse remains unaffected d. None of the above


28) Which
phenomenon occurs due to an increase in the channel bandwidth during the transmission of narrow pulses in order to avoid any intervention of signal distortion?
a.
Compression in time domain b. Expansion in time domain c. Compression in frequency domain d. Expansion in frequency domain


29) Why
are the negative & positive phase shifts introduced for positive & negative frequencies respectively in amplitude and phase spectra?
a. To
change the symmetry of the phase spectrum b. To maintain the symmetry of the phase spectrum c. Both a & b d. None of the above


30) Duality
Theorem / Property of Fourier Transform states that _________
a.
Shape of signal in time domain & shape of spectrum can be interchangeable b. Shape of signal in frequency domain & shape of spectrum can be interchangeable c. Shape of signal in time domain & shape of spectrum can never be interchangeable d. Shape of signal in time domain & shape of spectrum can never be interchangeable


31) Which
property of fourier transform gives rise to an additional phase shift of 2π ftd for the generated time delay in the communication system without affecting an amplitude spectrum?
a. Time
Scaling b. Linearity c. Time Shifting d. Duality


32) Which
among the below assertions is precise in accordance to the effect of time scaling? A : Inverse relationship exists between the time and frequency domain
a. A is
true & B is false b. A is false & B is true c. Both A & B are true d. Both A & B are false


33) Which
is/are the mandatory condition/s to get satisfied by the transfer function for the purpose of distortionless transmission?
a.
Amplitude Response should be constant for all frequencies b. Phase should be linear with frequency passing through zero c. Both a & b d. None of the above


34) What
is/are the crucial purposes of using the Fourier Transform while analyzing any elementary signals at different frequencies?
a.
Transformation from time domain to frequency domain b. Plotting of amplitude & phase spectrum c. Both a & b d. None of the above


35) What
is the possible range of frequency spectrum for discrete time fourier series (DTFS)?
a. 0 to
2π b. π to +π c. Both a & b d. None of the above


36) Which
among the following assertions represents a necessary condition for the existence of Fourier Transform of discrete time signal (DTFT)?
a.
Discrete Time Signal should be absolutely summable b. Discrete Time Signal should be absolutely multipliable c. Discrete Time Signal should be absolutely integrable d. Discrete Time Signal should be absolutely differentiable


37) What
is the nature of Fourier representation of a discrete & aperiodic signal?
a.
Continuous & periodic b. Discrete & aperiodic c. Continuous & aperiodic d. Discrete & periodic


38) Which
property of periodic signal in DTFS gets completely clarified / identified by the equation x (n – n0)?
a.
Conjugation b. Time Shifting c. Frequency Shifting d. Time Reversal


39) A
Laplace Transform exists when ______ A. The function is piecewise continuous
a. A
& B b. C & D c. A & D d. B & C


40) Where
is the ROC defined or specified for the signals containing causal as well as anticausal terms?
a.
Greater than the largest pole b. Less than the smallest pole c. Between two poles d. Cannot be defined


41) What
should be the value of laplace transform for the timedomain signal equation eat cos ωt.u(t)?
a. 1 / s + a with ROC σ
> – a b. ω / (s + a) 2 + ω2 with ROC σ > – a c. s + a / (s + a)2 + ω2 with ROC σ > – a d. Aω / s2 + ω2 with ROC σ > 0


42) According
to the timeshifting property of Laplace Transform, shifting the signal in time domain corresponds to the ______
a. Multiplication by est0
in the time domain b. Multiplication by est0 in the frequency domain c. Multiplication by est0 in the time domain d. Multiplication by est0 in the frequency domain


43) Which
result is generated/ obtained by the addition of a step to a ramp function?
a. Step Function shifted
by an amount equal to ramp b. Ramp Function shifted by an amount equal to step c. Ramp function of zero slope d. Step function of zero slope


44) Unilateral
Laplace Transform is applicable for the determination of linear constant coefficient differential equations with ________
a. Zero initial condition
b. Nonzero initial condition c. Zero final condition d. Nonzero final condition


45) What
should be location of poles corresponding to ROC for bilateral Inverse Laplace Transform especially for determining the nature of time domain signal?
a. On L.H.S of ROC
b. On R.H.S of ROC c. On both sides of ROC d. None of the above


46) Generally,
the convolution process associated with the Laplace Transform in time domain results into________
a. Simple multiplication
in complex frequency domain b. Simple division in complex frequency domain c. Simple multiplication in complex time domain d. Simple division in complex time domain


47) An
impulse response of the system at initially rest condition is basically a response to its input & hence also regarded as,
a. Black’s function
b. Red’s function c. Green’s function d. None of the above


48) When
is the system said to be causal as well as stable in accordance to pole/zero of ROC specified by system transfer function?
a. Only if all the poles
of system transfer function lie in lefthalf of Splane b. Only if all the poles of system transfer function lie in righthalf of Splane c. Only if all the poles of system transfer function lie at the centre of Splane d. None of the above


49) Correlogram
is a graph of ______
a. Amplitude of one signal
plotted against the amplitude of another signal b. Frequency of one signal plotted against the frequency of another signal c. Amplitude of one signal plotted against the frequency of another signal d. Frequency of one signal plotted against the time period of another signal


50) Which
theorem states that the total average power of a periodic signal is equal to the sum of average powers of the individual fourier coefficients?
a. Parseval’s Theorem
b. Rayleigh’s Theorem c. Both a & b d. None of the above


51) According
to Rayleigh’s theorem, it becomes possible to determine the energy of a signal by________
a. Estimating the area
under the square root of its amplitude spectrum b. Estimating the area under the square of its amplitude spectrum c. Estimating the area under the onefourth power of its amplitude spectrum d. Estimating the area exactly half as that of its amplitude spectrum


52) What
would be the value of normalized energy for the causal exponential pulse shown below?
a. 8α
b. 1 / 8α c. 1 / 8α d. 8α


53) What
does the spectral density function of any signal specify?
a. Distribution of energy
or power b. Consumption of energy or power c. Conservation of energy or power d. Generation of energy or power


54) Which
among the below mentioned transform pairs is/are formed between the autocorrelation function and the energy spectral density, in accordance to the property of Energy Spectral Density (ESD)?
a. Laplace Transform
b. ZTransform c. Fourier Transform d. All of the above


55) The
ESD of a real valued energy signal is always _________
a. An even (symmetric)
function of frequency b. An odd (nonsymmetric) function of frequency c. A function that is odd and halfwave symmetric d. None of the above


56) Which
among the below mentioned assertions is /are correct? a. Greater the value of correlation function, higher is the similarity level
a. Only C
b. Only B c. A & D d. B & C


57) Which
function has a provision of determining the similarity between the signal and its delayed version?
a. Autocorrelation
Function b. Crosscorrelation Function c. Both a & b d. None of the above


58) Which
property is exhibited by the autocorrelation function of a complex valued signal?
a. Commutative property
b. Distributive property c. Conjugate property d. Associative property


59) Where
does the maximum value of autocorrelation function of a power signal occur?
a. At origin
b. At extremities c. At unity d. At infinity


60) What
does the set comprising all possible outcomes of an experiment known as?
a. Null event
b. Sure event c. Elementary event d. None of the above


61) What
does an each outcome in the sample space regarded as?
a. Sample point
b. Element c. Both a & b d. None of the above


62) Mutually
Exclusive events ________
a. Contain all sample
points b. Contain all common sample points c. Does not contain any common sample point d. Does not contain any sample point


63) What
would be the probability of an event ‘G’ if G denotes its complement, according to the axioms of probability?
a. P (G) = 1 / P (G)
b. P (G) = 1 – P (G) c. P (G) = 1 + P (G) d. P (G) = 1 * P (G)


64) What
would happen if the two events are statistically independent?
a. Conditional probability
becomes less than the elementary probability b. Conditional probability becomes more than the elementary probability c. Conditional probability becomes equal to the elementary probability d. Conditional as well as elementary probabilities will exhibit no change


65) What
would be the joint probability of statistically independent events that occur simultaneously?
a. Zero
b. Not equal to zero c. Infinite d. None of the above


66) Consider
the assertions given below A : CDF is a monotonously increasing function Which among them is correct according to the properties of PDF?
a. A is true & B is
false b. A is false & B is true c. Both A & B are true but B is a reason for A d. Both A & B are false since B is not a reason for A


67) The
Joint Cumulative Density Function (CDF) _____
a. Is a nonnegative
function b. Is a nondecreasing function of x & y planes c. Is always a continuous function in xy plane d. All of the above


68) What
is the value of an area under the conditional PDF?
a. Greater than ‘0’ but
less than ‘1’ b. Greater than ‘1’ c. Equal to ‘1’ d. Infinite


69) When
do the conditional density functions get converted into the marginally density functions?
a. Only if random
variables exhibit statistical dependency b. Only if random variables exhibit statistical independency c. Only if random variables exhibit deviation from its mean value d. None of the above


70) Which
among the below mentioned standard PDFs is/are applicable to discrete random variables?
a. Gaussian distribution
b. Rayleigh distribution c. Poisson distribution d. All of the above


71) A
random variable belongs to the category of a uniform PDF only when ______
a. It occurs in a finite
range b. It is likely to possess zero value outside the finite range c. Both a & b d. None of the above


72) What
would happen if the value of term [(mx) / (σ √2)] increases in the expression of Guassian CDF?
a. Complementary error
function also goes on increasing b. Complementary error function goes on decreasing c. Complementary error function remains constant or unchanged d. Cannot predict


73) Which
type of standard PDFs has/ have an ability to describe an integer valued random variable concerning to the repeated trials carried /conducted in an experiment?
a. Binomial
b. Uniform c. Both a & b d. None of the above

ELECTRONICS AND COMMUNICATION ENGINEERING IMPORTANT MCQSIGNALS AND SYSTEMS
October 23, 2016
ECE MCQ PDF, General
thank u so much sir
within two days i will upload all others pdf also