JNTU
JNTU B.Tech III DIGITAL SIGNAL PROCESSING Previous Question Paper (May - 2019 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
What is the necessary and sufficient condition on the impulse response for stability.
Answer
A discrete-time LTI system is BIBO stable if and only if its impulse response h(n) is absolutely summable, expressed as the condition:
Find the z-transform of the sequence x(n) = (1/3)^n u(n) - (1/3)^n u(-n-1).
Answer
For x(n) = (1/3)n u(n) - (1/3)n u(-n-1), the Z-transform is calculated as:
X(z) = 1/(1 - (1/3)z-1) for |z| > 1/3, minus (-1/(1 - (1/3)z-1)) for |z| < 1/3.
Since the regions of convergence (ROC) do not overlap, the Z-transform does not exist for this sequence as a whole unless defined in a specific ROC context, but formally:
Write the differences between DFT and FFT.
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What is the speed improvement factor in calculating 64-point DFT of a sequence using direct computation and FFT algorithms?
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Compare analog and digital filters.
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What the properties of the bilinear transformation?
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Describe the various characteristic features of windows.
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Distinguish between FIR and IIR filters.
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What is mean by limit cycle oscillations?
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What is significance of decimator and interpolator in multirate DSP?
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Part B
Obtain the direct form-II realization for the given system: y(n) - 0.1y(n-1) - 0.72y(n-2) = 0.7x(n) - 0.252x(n-2)
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Determine the transfer function H(Z) of the system given by y(n) + y(n-1) = 5x(n) + 4x(n-1) + 6x(n-2)
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Find the impulse response of the system described by difference equation y(n) - 3y(n-1) - 4y(n-2) = x(n) + 2x(n-1) using z transform.
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Test if the following system is linear time invariant or not: y(n) = Ax(n) + B
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Find the y(n) for the sequences x(n)={1,-1,1,2,1,0,1,-4,3,2,1,0,1,1} and h(n)={1,1,2,1} using overlap-save method.
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Discuss the relation between DFT and Z-transform.
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Find the 8-point DFT of {2,1,2,1} using DIF-FFT. Draw the signal flow graph for N=8 with intermediate values.
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Determine the order and poles of type-I chebyshev low pass filter for the given specifications: αp = 1 dB, αs = 40 dB, Ωp = 1000 rad/sec, Ωs = 2000 rad/sec.
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Show that s = (2/T) * (1 - z^-1) / (1 + z^-1) in the designing of IIR filter using bilinear transformation method.
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Discuss impulse invariance method. What are its disadvantages?
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Compare Hamming window and Rectangular window in terms of characteristics.
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Prove that for a linear phase FIR filter the impulse response is symmetric.
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Design an ideal low pass filter with frequency response H(e^jω) = 1 for -π/2 ≤ ω ≤ π/2, and 0 for π/2 ≤ ω ≤ π. Find the values of h(n) using hamming window for N=11. Find the H(z).
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Discuss the finite word length effects in FIR filters.
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What is Round-off Noise in IIR Digital Filters? Discuss its effects in IIR filters.
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Describe the interpolation process with factor D and obtain the necessary expressions.
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