Dhirajlal Gandhi College of TechnologyDepartment of ECESignals and Systems

1. Graphical representation of a signal in time domain is called

a. frequency spectrum b. frequencyc. waveformd. none of the above

2. Graphical representation of a signal in frequency domain is called

a. frequency spectrum b. frequencyc. waveformd. none of the above

3. A signal can be represented in

a. time domainb. frequency domainc. both (a) and (b)d .phase domain

4.Analog signal can be converted in to discrete-time signal by

a. samplingb. codingc. quantizingd. none of the above

5. A deterministic signal has

a. no uncertainty b. uncertaintyc. partial uncertaintyd. certain

6. A random signal has

a. no uncertainty b. uncertaintyc. partial uncertaintyd. certain

7. A system is a

a. Physical deviceb. mathematical model c. linear modeld. ideal device8. A system whose output depends on future input is a

a. static systemb. dynamic systemc. non-casual systemd. both (b) and (c)

9. A non-anticipative system is a

a. static systemb. dynamic systemc. casual systemd. non-casual system10.A system which has a unique relation between its input and output is called

a. linear systemb. casual systemc. time-invariant systemd. invariant system

11.A system which does not have a unique relation between its input and output is called

a. non-linear systemb. non-casual systemc. time-variant system d. non-invariant system

12. y(n)=x(n)u(n) is for a

a. static, linear systemb. casual, time-invariant system c. both (a) and (b) d. none of the above

13.y(n) = x(n) +nx(n-1) is for a

a. dynamic system b. casual system c. linear systemd. all the above

14. Two vectors are orthogonal if their dot product is

a. 0b. 1c. 2d. infinity

15. Two signals are orthogonal if the integral of their product is

a. 0b. 1c. 2d. Infinity

16.Fourier series applied to

a. Only periodic signals b. only aperiodic signals c. both periodic and aperiodic signalsd. random signal

17. For the existence of Fourier series, Dirichlets condition are

a. Necessary b. sufficientc. necessary and sufficient d. none of thos

18.The net area of sinusoids over complete periods are

a. Finite b. infinitec. zerod. On

19. Even symmetry is also called

a. Rotational symmetryb. mirror symmetryc. full symmetry d. half symmetry

20. The most widely used Fourier series is

a. Trigonometric series b .cosine series c. exponential seriesd.none

21. A trigonometric Fourier series has

a. One-side spectrum b. two-sided spectrum c. both (a) and (b)d.non

22. A exponential Fourier series has

a. One-side spectrum b. two-sided spectrum c. both (a) and (b)d.none

23.The frequency spectrum of a periodic signal is

a. Continuous b. discrete c. both (a) and (b) d. none

24.The frequency spectrum of an aperiodic signal is

a. Continuous b. discrete c. both (a) and (b) d. none

25.The time domain representation of a signal graphically is called

a. Waveform b. spectrum c. magnitude d. phase

26.The frequency domain representation of a signal graphically is called

a. Waveform b. spectrum c. magnitude d. phase

27.Fourier transform is applicable to

a. Only periodic signalsb. Only aperiodic signals c. both (a) and (b)d. random signal

28.In the frequency spectrum of an aperiodic signal, the spacing among the components is

a. Large b. smallc. infinityd. zero

29.A periodic signal becomes an aperiodic signal if its time period approaches

a. Ten times pulse width b. infinityc. hundreds times pulse width d. zero

30.If the frequency spectrum of a function is discrete ,then the function is:

a. discreteb. aperiodicc. periodicd. random

31.If the frequency spectrum of a function is continuous ,then the function is:

a. discreteb. aperiodicc. periodicd. random

32.The sinc function x(t) is defined as x(t)=

a. sin5t/5t b. sint/5tc. sin5t/5d. sin5t/t

33.The signum function x(t) can be written as

a. u(t)-1b.2u(t)-1c.1-u(t)d.u(t)+u(-t)

34.Hilbert transform

a.LPFb.90 phase shifterc.HPFd.180 phase shifter

35.The Fourier transform of x(-t) is

a.x(w)b.x(-w)c.x(1/w)d.-x(w)

36. The Fourier transform of autocorrelation is

a. PSD b.ESDc.both of (a) and (b)d.none

37. In Communication, the sampling technique leads to

a. More efficiency b .low cost c. high speed d. all the above

38.Practical sampling is

a. PAMb.PCMc.PPMd.PWM

39.The sampling rate is always between

a. 0 and 2Bb. 2B and 4Bc. B and 2B d.>4B

40.A band pass signal extending from 5kHz to 15 kHz is to be sampled at

a. 5kHz b.15kHzc.20kHzd. between 5kHz and 15kHz

41.The impulse response of a system is h(t).When the input is x(t0,the output y(t) will be

a. h(t)x(t) b.h(t)(t)c.h(t)*x(t)d.x(t) (t)

42.The impulse response of a system is h(t).When the input is (t), the output y(t) will be

a.y(t)b, (t)c.h(t)d. none

43. The convolution u(t-3) *u(t-3) is

a. u(t-6) b.u(t-3)u(t-3)c.(t-6)d.(t-3)(t-3)

44.which one of the following cannot be the ROC of 5/(s+1)(s+2)

a. Re(s)>-1b.Re(s)