Unit 3 - Practice Quiz

ECE220 50 Questions
0 Correct 0 Wrong 50 Left
0/50

1 Which of the following signals can be represented by a Fourier Series?

A. Any continuous time signal
B. Periodic power signals
C. Aperiodic energy signals
D. Energy signals only

2 The condition for a signal to be periodic with period is:

A. for all
B. for only
C.
D.

3 In the trigonometric Fourier series representation, the term represents:

A. Fundamental frequency component
B. Phase angle
C. RMS value of the signal
D. Average (DC) value of the signal

4 The fundamental angular frequency is related to the time period by:

A.
B.
C.
D.

5 Which of the following is the correct synthesis equation for the Exponential Fourier Series?

A.
B.
C.
D.

6 The set of functions form an:

A. Orthogonal set
B. Exponential set
C. Inconsistent set
D. Aperiodic set

7 For the Exponential Fourier Series coefficient , what is the value of ?

A. The average value of
B. 0
C. The RMS value
D.

8 If a periodic signal is even, i.e., , its Trigonometric Fourier Series contains:

A. Sine terms only
B. Sine terms and a DC term
C. Cosine terms and a DC term
D. Odd harmonics only

9 If a periodic signal is odd, i.e., , which coefficients are zero?

A. and
B. and
C. only
D. only

10 The relationship between the exponential Fourier coefficient and trigonometric coefficients (for ) is:

A.
B.
C.
D.

11 The Dirichlet conditions provide sufficient conditions for:

A. The periodicity of a signal
B. The convergence of the Fourier Series
C. The stability of a system
D. The linearity of a system

12 Which of the following is NOT a Dirichlet condition?

A. must be absolutely integrable over one period
B. must differ from zero for all
C. must have a finite number of maxima and minima in one period
D. must have a finite number of discontinuities in one period

13 At a point of discontinuity , the Fourier series of converges to:

A. 0
B.
C.
D.

14 The Gibbs phenomenon refers to:

A. The divergence of Fourier series for non-periodic signals
B. The phase shift in the frequency spectrum
C. Oscillatory behavior and overshoot near discontinuities in a truncated Fourier series
D. The decay of coefficients for smooth signals

15 For a real-valued signal , the exponential Fourier series coefficients satisfy the conjugate symmetry property:

A.
B.
C.
D.

16 A signal has half-wave symmetry if:

A.
B.
C.
D.

17 A signal with half-wave symmetry contains only:

A. Odd harmonics
B. Even harmonics
C. DC component and even harmonics
D. Cosine terms only

18 Parseval's relation for the Exponential Fourier Series states that the average power is:

A.
B.
C.
D.

19 If , then the coefficients of the time-shifted signal are:

A.
B.
C.
D.

20 If , then the coefficients of the time-reversed signal are:

A.
B.
C.
D.

21 The Fourier series coefficients of the derivative of a periodic signal are related to (coefficients of ) by:

A.
B.
C.
D.

22 For the integration property to hold (i.e., coefficients become ), what condition must the signal satisfy?

A. It must be even
B. It must be discontinuous
C. Its average value must be zero
D. It must be odd

23 Multiplication of two periodic signals and in the time domain corresponds to what operation on their Fourier series coefficients?

A. Addition
B. Multiplication
C. Discrete Convolution
D. Differentiation

24 The plot of versus frequency (or index ) is known as the:

A. Power density
B. Magnitude spectrum
C. Phase plot
D. Phase spectrum

25 For a real-valued signal, the magnitude spectrum is:

A. An odd function of
B. An even function of
C. Always zero
D. Non-symmetric

26 For a real-valued signal, the phase spectrum is:

A. Always positive
B. Constant
C. An even function of
D. An odd function of

27 The Fourier series of an Impulse Train consists of:

A. Zero coefficients
B. Sine waves only
C. Constants (all are equal)
D. Decaying exponentials

28 If a signal is real and even, its exponential Fourier coefficients are:

A. Real and Odd
B. Real and Even
C. Complex
D. Purely Imaginary and Odd

29 If a signal is real and odd, its exponential Fourier coefficients are:

A. Complex
B. Purely Imaginary and Even
C. Real and Even
D. Purely Imaginary and Odd

30 The frequency spectrum of a continuous time periodic signal is:

A. Discrete and periodic
B. Continuous and aperiodic
C. Continuous and periodic
D. Discrete and aperiodic

31 What happens to the Fourier coefficients if the signal is time-scaled to where ?

A. The coefficients change to
B. The coefficients remain the same, but the fundamental frequency becomes
C. The coefficients are squared
D. The coefficients become zero

32 Which signal has Fourier coefficients that decay as ?

A. Impulse train
B. A smooth continuous signal
C. A signal with discontinuous first derivative (e.g., Triangular wave)
D. A signal with jump discontinuities (e.g., Square wave)

33 Which signal has Fourier coefficients that decay as ?

A. Triangular wave (Continuous but discontinuous slope)
B. Square wave
C. Impulse train
D. Sine wave

34 When simulating the frequency spectrum of a periodic signal using software, the spacing between spectral lines is determined by:

A. The phase of the signal
B. The sampling frequency
C. The fundamental frequency
D. The amplitude of the signal

35 In a software simulation, calculating Fourier Series coefficients often involves numerical integration. Which method effectively implements this for discrete data?

A. Laplace Transform
B. Fast Fourier Transform (FFT)
C. Z-Transform
D. Convolution

36 The Power Spectral Density (PSD) of a periodic signal describes:

A. The total energy of the signal
B. How energy is distributed with frequency
C. The phase shift at each frequency
D. How power is distributed with frequency

37 If , the exponential Fourier coefficients are:

A.
B. , others 0
C.
D. , others 0

38 If , the exponential Fourier coefficients are:

A.
B.
C.
D.

39 What is the Fourier Series representation of a constant signal ?

A.
B. It does not exist
C. for all
D. for

40 The linearity property of Fourier Series implies that if , then its coefficients are:

A.
B.
C.
D.

41 Frequency shifting: If the coefficients are shifted to , the time domain signal becomes:

A.
B.
C.
D.

42 The Fourier series expansion of a periodic square wave with zero DC value contains:

A. Odd harmonics of sine (or cosine) terms
B. Only the fundamental component
C. Even harmonics only
D. All harmonics

43 If a periodic signal is decomposed into even and odd parts , then generates:

A.
B. Zero coefficients
C. Im
D. Re

44 The total power of a periodic signal is 10 W. If the DC component power is 2 W, what is the power contained in the AC components?

A. 12 W
B. 8 W
C. 100 W
D. 5 W

45 Why is the exponential form of Fourier series often preferred over the trigonometric form in software simulation and analysis?

A. It only deals with positive frequencies
B. It has no convergence issues
C. Mathematical compactness and ease of manipulation
D. It avoids complex numbers

46 For a periodic signal , if , the Fourier Series becomes:

A. Laplace Transform
B. Fourier Transform
C. Z-Transform
D. Discrete Fourier Series

47 Which mathematical tool is used to prove the orthogonality of the basis functions in Fourier Series?

A. Integration over one period
B. Convolution
C. Limit as
D. Differentiation

48 If a periodic signal is time-shifted, which aspect of its spectrum changes?

A. Neither magnitude nor phase
B. Phase spectrum only
C. Both magnitude and phase
D. Magnitude spectrum only

49 In the context of software simulation, 'Aliasing' would occur if:

A. The signal is not periodic
B. The signal has no DC component
C. The sampling rate is too low compared to the highest frequency harmonic
D. The Fourier series is truncated

50 The RMS value of a periodic signal can be calculated from the Fourier coefficients as:

A.
B.
C.
D.