Unit 3 - Practice Quiz

ECE220 50 Questions
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1 Which of the following signals can be represented by a Fourier Series?

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

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

A.
B. for all
C. for only
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. Aperiodic set
B. Orthogonal set
C. Exponential set
D. Inconsistent set

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

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

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

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

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

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

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

12 Which of the following is NOT a Dirichlet condition?

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

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

A.
B.
C. 0
D.

14 The Gibbs phenomenon refers to:

A. The divergence of Fourier series for non-periodic signals
B. Oscillatory behavior and overshoot near discontinuities in a truncated Fourier series
C. The phase shift in the frequency spectrum
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. Even harmonics
B. Odd 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 odd
C. Its average value must be zero
D. It must be discontinuous

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

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

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

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

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

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

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

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

27 The Fourier series of an Impulse Train consists of:

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

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

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

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

A. Complex
B. Real and Even
C. Purely Imaginary 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. Discrete and aperiodic
D. Continuous and periodic

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

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

32 Which signal has Fourier coefficients that decay as ?

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

33 Which signal has Fourier coefficients that decay as ?

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

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

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

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

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

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

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

37 If , the exponential Fourier coefficients are:

A. , others 0
B.
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. for all
B. It does not exist
C. for
D.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

A.
B.
C.
D.