# Digital Signal Processing Past Papers Exam Questions

By Prof. Fazal Rehman Shamil

## Guess Paper 1:Digital Signal Processing Fall – 2020 Past Papers

Time Allowed: 3 hours

Total Marks:    70, Passing Marks (35)

Q.1 Explain operation of low pass FIR filter with the help of diagram.

Q2. Explain in detail Radix-2 FFT algorithm

Q3. Explain the following terms.
a) Signal Magnitude
b) Signal power
c) Signal Amplitude,

Q4. Obtain the z-transform of the sequence.

U(k)={ 1 2 2 2 1 1 1}

Q5. Explain the working principal of Butterfly and Bit Reversal Algorithm.

Q6. Differentiate between band pass signal, low pass signal and high pass signal.

Q7. Define the following terms.
a) Sampling
b) Aliasing
c) Convolution

## Guess Paper 2:Digital Signal Processing Spring- 2020 Past Papers

Time Allowed: 3 hours

Total Marks:    70, Passing Marks (35)

Q1: Define the following terms.
a) Autocorrelation
b) Cross-correlation sequences
c) Causality
d) Time invariance
e) Linearity

Q2: Determine and plot the impulse response of FIR system

Q3: Find the z-transform and Region of convergence(ROC) of the following ;

a. X[n]= σ[n]
b. X[n]= σ[n-1]
c. X[n]= σ[n+1]

Q4: Draw the direct form structure of FIR filter?

Q5 What is sampling? Write note on Shannon sampling theorem?

Q6: Find the inverse z-transform using partial fraction expansion

Q7: (a) Determine the z-transforms of the following sequences and their respective ROCs:
i). X1[n] = – αn μ [-n-1] ii) X2[n] = α μ[n+1]
i) Is the cascade connection of two stable LTI systems also stable?
ii) Is the parallel connection of two stable LTI systems also stable?

Q8: Explain any two of them
(a) High pass filter
(b) Periodic and Aperiodic period
(c) Aliasing

## Guess Paper 3:Digital Signal Processing Spring- 2019 Past Papers

Time Allowed: 3 hours

Total Marks:    70, Passing Marks (35)

Q1: Choose the suitable option.
1. Determine the convolution sum of two sequences x(n) = {3, 2, 1, 2} and h(n) = {1, 2, 1, 2}
a. y(n) = {3,8,8,12,9,4,4} b. y(n) = {3,8,3,12,9,4,4}
c. y(n) = {3,8,8,12,9,1,4} d. y(n) = {3,8,8,1,9,4,4}
2. Application of Convolution
a. FIR Filtering b. Addition c. Manipulation d. None of these
3. Condition for aliasing problem
a. fs<fm b.fs<2fm c. fs=fm d. all of these
4. The interface between an analog signal and a digital processor is
a. D/A converter b. A/D converter c. Modulator d. Demodulator
5. DTFT is the representation of
a. Periodic Discrete time signals b. Aperiodic Discrete time signals
c. Aperiodic continuous signals d. Periodic continuous signals
6. DIT algorithm divides the sequence into
a. Even and odd samples b. Positive and negative values
c. Upper higher and lower spectrum d. Small and large samples
7. The anti causal sequences have ______ components in the left hand sequences.
a. Positive b. Negative c. Both a and b d. None of the above.
8. FIR filters ________
a. are non-recursive b. are recursive c. use feedback

9. How is the sensitivity of filter coefficient quantization for FIR filters? Power
a. Low b. Moderate c. High d. Unpredictable
10. Suppose that x(t) is bandlimited to 8 kHz (that is, X( f ) = 0 for |f| > 8000), then what isthe Nyquist rate for x(t)cos(2π . 1000t)?
a. 18KHz. b. 4KHz. c. 16KHz. d. 5KHz.

Q2: Distinguish Between FIR Filters And IIR Filters?
Q3: a) Define Discrete Time Signal and Discrete Time System?
b) State The Classification Of Discrete Time Signals?
Q4: a) Define Periodic and Aperiodic Signal?
b) Define Symmetric and Antisymmetric Signal?
Q5: Find DFT of sequence
x(n) = [1, 1, -2, -2]
b) Define Aliasing and Sampling Theorem.
Q6: Using Butterfly method, compute the 4 point FFT for the signal.

Q7: Write down the procedure to design the FIR Filter Using Frequency Sampling Method. Prof.Fazal Rehman Shamil (Available for Professional Discussions)
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