Download Digital Signal Processing Concepts and more Exams Nursing in PDF only on Docsity!
DGT301 - Part 1 - Digital Signal
Processing
QN=1 The highest rate of oscillation in a discrete-time sinusoid is attained when a. f= b. f=1/ c. f=1 - Answer b QN=2 y(n) = 2x(n) - x(n-1) + x(n-2). The impulse response h(n) contains the sequence: a. infinite values b. 2, -1, 1; h(0) = 2 c. 1, -1, 2; h(0) = 1 d. 2, -1, 1; h(0) = -1 - Answer b QN=3 The graphical representation of signal x(-n-3) is from the one of signal x(n) by: a. folding and right shift operations. b. folding and left shift operations. c. folding operation. d. right shift operation. - Answer b QN=4 Suppose a low-pass moving-average filter uses the coefficients 0.25, 0.25, 0.25, and 0.25. What will the output sequence be with an input signal at a constant value of 2? a. 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, and so on. b. 0.5, 1.0, 1.5, 2.0, 2.0, 2.0, and so on. c. 1.0, 2.0, 3.0, 4.0, 4.0, 4.0, and so on. d. None of the others. - Answer b QN=5 When two cosin waves of frequencies 30 and 50 Hz are multiplied together, the Nyquist rate for resulting signal is (in Hertz): a. 30 b. 50 c. 80 d. 160 - Answer d QN=6 The following system y[n] = nx[n] is: a. nonlinear.
b. linear. - Answer b QN=7 If FT{x(n)} = X(w), then FT{x(n)} = ______. a. X(w). b. X(-w). c. X(-w). d. X(1/w). - Answer c QN=8 FT{x(n)} = _______. a. X(-w). b. -X(-w). c. X*(w). d. 0 - Answer a QN=9 A signal consists a pure tone of frequency 100 Hz. It is sampled at f(sampling)= 1024 Hz for 0.5s. The FFT of the sampled signal using a rectangular window_______________________. a. will show a single peak at 100Hz. b. will exhibit spectral leakage. c. will be twice as fast as a DFT on the same number of samples. - Answer a QN=10 FFT is a. an acronym for fast frequency transform. b. a transform for determining the frequency content of continuous-time aperiodic signals. c. an efficient algorithm for calculating the DFT when N is a power of 2. d. an algorithm for calculating the length of the diagonal of a right-angled triangle. - Answer c QN=11 The following system y[n] = x[n] - x[n-1] is: a. causal b. non causal - Answer a QN=12 Digital signal processing of an analog signal may be preferable to processing the signal directly in the analog domain because: a. Digital programmable system allows flexibility in reconfiguration the digital signal processing operations simply by changing the program. b. A digital system provides much better control of accuracy requirements. c. The digital signal processing method also allows for the implementation of more sophisticated signal processing algorithms. d. All of the others. - Answer d QN=13 The fastest way to compute the frequency content of a signal is to a. choose the number of samples as a power of 2, and use an FFT algorithm. b. choose any reasonable number of samples and use a generic DFT algorithm. c. perform the calculations using pencil and paper.
b. X(z * 2) c. X(z - 2) d. X(z +2 ) - Answer a QN=22 The fundamental period (T for continuous-time signals, N for discrete-time signals) of the following periodic signals: x(t)=cos(pit)+2sin(4pit). a. 2 b. 3 c. 4 d. 5 - Answer a QN=23 What name is given to the lowest frequency in a Fourier series? a. Fundamental. b. First harmonic. c. Both "fundamental" and "first harmonic". d. None of the others. - Answer c QN=24 Consider the analog signal : x(t)=3cos(50pit)+10sin(300pit)-cos(200pi*t). What is the Nyquist rate for this signal? a. 100 Hz b. 200 Hz c. 300 Hz d. 600 Hz - Answer c QN=25 Find the dB power gain of an electronic circuit that has input and output resistances of 600 ohms, an input signal of 0.2 mV, and an output signal of 4V. a. 76 b. 86 c. 96 d. 106 - Answer b QN=26 When two sine waves of frequencies 50 and 30 Hz are multiplied together, the resulting signal consists of the following frequencies (in Hertz): a. 50 and 30. b. 80 and 20. c. -50 and 30. d. 100 and 60. - Answer b QN=27 Suppose a low-pass moving-average filter uses the coefficients 0.25, 0.25, 0.25, and 0.25. What will the output sequence be with an input signal at a constant value of 2? a. 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, and so on. b. 0.5, 1.0, 1.5, 2.0, 2.0, 2.0, and so on. c. 1.0, 2.0, 3.0, 4.0, 4.0, 4.0, and so on. d. None of the others. - Answer b
QN=28 The DFT a. is the Fourier transform in continuous frequency domain. b. is considered as the sampling of the Fourier transform of an aperiodic discrete-time sequence. c. is considered as the sampling of the Fourier transform of a periodic discrete-time sequence. - Answer b QN=29 DFT is a. an acronym for fast frequency transform. b. a transform for determining the frequency content of continuous-time aperiodic signals. c. an efficient algorithm for calculating the DFT when N is a power of 2. d. none of the others - Answer d QN=30 A high-pass moving-average filter uses the coefficients -0.25, -0.25, 1.0, -0.25, and -025. What will the output sequence be with an input signal at a constant value of 2? a. -0.5, -1.0, 1.0, 0.5, 0, 0, 0, and so on. b. -0.25, -1.25, 1.25, 1.75, 2.0, 2.0, 2.0, and so on. c. 0.5, 1.5, 1.0, 0, -1.5, -1.5, -1.5, and so on. d. None of the others. - Answer a QN=31 Divide-and-conquer approach of DFT a. is based on the composition of an N-point DFT into successively smaller DFTs. b. leads to a family of computationally efficient algorithms know collectively as FFT algorithms. c. is the radix-2 FFT algorithm. d. is based on basic butterfly computation. - Answer b QN=32 What is the name given to the frequency that is exactly half of the sampling frequency? a. Anti-aliasing frequency b. Nyquist frequency c. Shannon frequency d. Sample-and-hold frequency - Answer b QN=33 The resolution of a digital signal can be increased by a. Increasing the number of bits. b. Decreasing the number of bits. c. Sampling the signal less often. d. Using a faster computer. - Answer a QN=34 The DC value of the signal having the following samples, 3.5, 3.5, -2.0, -3.5, 2.0, -1.5, 3.0, 3.0, is a. 1. b. 3.
d. One dimensional, single channel, discrete-time, digital. - Answer b QN=42 Two digital filters can be operated in cascade. Or, the same effect can be achieved by: a. adding their coefficients. b. subtracting their coefficients. c. convolving their coefficients. d. averaging their coefficients and then using a Blackman window. - Answer c QN=43 We have discussed transducers that produce electrical signals. Which of the following transducers does the opposite-takes in an electrical signal and converts it to some other type of signal? a. Loudspeaker b. Thermistor c. Thermocouple d. Strain gauge - Answer a QN=44 The z-transform of the signal x(n) = u(n) is: a. 1/(1-1/z), ROC: |z|>1. b. 1/(1-1/z), ROC: |z|<1. c. (1-1/z), ROC: |z|>1. d. (1-1/z), ROC: |z|<1. - Answer a QN=45 Two discrete-time system U and V are connected in cascade to form a new system W. Select a false statement: a. If U and V are causal, then W is causal. b. If U and V are nonlinear, then W is nonlinear. c. If U and V are linear, then W is linear. d. If U and V are stable, then W is stable. - Answer b An LTI system is causal if and only if its impluse response is a. zero for negative values of n. b. noncausal. c. constant. - Answer a QN=47 With real signals, X(w) = ______. a. X(-w). b. X(w). c. -X*(-w). d. 1 - Answer a QN=48 Which of the following is not required for correlation? a. Accumulation b. Multiplication c. Flipping d. Shifting - Answer c
QN=49 The transition bandwidth of an ideal filter is a. 0 Hz. b. half of the passband. c. half of the stopband. d. none of the others. - Answer a QN=50 The following system y[n] = x[n] - x[n-1] is: a. time invariant b. time variant - Answer a QN=51 The number of possible filter structures are a. 2 b. 3 c. 5 d. infinite - Answer d
