COMMUNICATION ENGINEERING QUESTION BANK
DEPARTMENT OF
ELECTRONICS AND COMMUNICATION ENGINEERING
QUESTION BANK
TWO MARKS:
1. Define about DFT and IDFT?
2. Find the values of WNk ,When N=8, k=2 and also for k=3.
3. Compare DIT radix-2 FFT and DIF radix -2
FFT.
4. Draw the radix-2 FFT–DIF butterfly diagram.
5. Draw the radix-2 FFT–DIT butterfly diagram.
6. What is the necessity of sectioned
convolution in signal processing?
7. Define Correlation of the sequence.
8. State any two DFT properties.
9. Why impulse invariant transformation is not
a one-to-one mapping?
PART - B
1. a) Compute 4- point DFT of casual three
sample sequence is given by,
x(n) = 1/3, 0_n_2
= 0, else (10)
b) State and prove shifting property of DFT. (6)
2. Derive and draw the radix -2 DIT algorithms
for FFT of 8 points. (16)
3. Compute the DFT for the sequence {1, 2, 0,
0, 0, 2, 1, 1}. Using radix -2 DIF FFT and radix -2 DIT- FFT algorithm. (16)
4. Find the output y(n) of a filter whose
impulse response is h(n) = {1, 1, 1} and input signal x(n) = {3, -1, 0, 1, 3,
2, 0, 1, 2, 1}. Using Overlap add overlap save method. (16)
5. In an LTI system the input x(n) = {1, 1,
1}and the impulse response h(n) = {-1, -}Determine the response of LTI system
by radix -2 DIT FFT (16)
6. Find the output y(n) of a filter whose
impulse response is h(n) = {1, 1, 1} and input signal x(n) = {3, -1, 0, 1, 3,
2, 0, 1, 2, 1}. Using Overlap save method (16)
UNIT-II: DIGITAL FILTERS DESIGN
TWO MARKS:
1. Differentiate IIR filters and FIR filters.
2. Write the characteristics features of
Hanning window
3. Define pre-warping effect? Why it is
employed?
4. Give any two properties of Butterworth
filter.
5. When a FIR filter is said to be a linear
phase FIR filter
6. Write the characteristics features of
rectangular window.
7. Write the expression for Kaiser window
function..
8. What are the advantages and disadvantages of
FIR filters?
9. Write the characteristics features of
Hamming window
10. Why mapping is needed in the design of digital
filters?
PART - B
1 . With a neat sketch explain the design of
IIR filter using impulse invariant transformation. (16)
2. Apply impulse invariant transformation to H(S)
= (S +1) (S + 2) with T =1sec and find H(Z). (16)
3. For a given specifications of the desired
low pass filter is
0.707 _ |H(_)| _1.0, 0 _ _ _ 0.2_|H(_)| _ 0.08, 0.4 _ _ _ _ _
Design a Butterworth filter using bilinear
transformation. (16)
4. Explain the procedural steps the design of
low pass digital Butterworth filter and list its properties.
(16)
5. The normalized transfer function of an
analog filter is given by,
1Ha(Sn)= Sn2 + 1.414Sn +1 with
a cutoff frequency of 0.4 _, using bilinear transformation.
(16).
6. List the three well known methods of design
technique for IIR filters and explain any one. (16)
7. Design a low pass filter using rectangular
window by taking 9 samples of w(n)
and with a cutoff frequency of 1.2
radians/sec.Using frequency sampling method, design a band pass FIR filter with
the following specification. Sampling frequency Fs =8000 Hz, Cutoff frequency fc1 =1000Hz, fc2 =3000Hz.Determine the filter coefficients for N
=7. (16)
8. Design an ideal high pass filter with Hd(ej _) =
1 ; _/4 _ | _| _ _= 0
; | _| _ _/4
Using Hamming window with N =11 (16)
9. Determine the coefficients of a linear phase
FIR filter of length N =15 which has a symmetric unit sample response and a
frequency response that satisfies the conditions H (2 _k
/15) = 1; for k = 0, 1, 2, 3
= 0.4 ; for k = 4
= 0; for k = 5, 6, 7 (16)
10. Design and implement linear phase FIR
filter of length N =15 which has following unit sample sequence H(k) = 1 ; for
k = 0, 1, 2, 3
= 0
; for k =4, 5, 6, 7 (16)
11. Convert the analog filter in to a digital
filter whose system function is
S + 0.2 H(s) = (S + 0.2)2 + 9.Use Impulse Invariant Transformation
.Assume T=1sec (16)
12. The Analog Transfer function H(s)=
----------------.Determine H(Z) .Using Impulse (S+1) (S+2) Invariant Transformation
.Assume T=1sec . (8)
13. Apply Bilinear Transformation to H(s)=
------------- with T=0.1 sec. (8)
(S+2)(S+3)
UNIT-III: EFFECTS OF FINITE WORD LENGTH
TWO MARKS:
1. What are the effects of finite word length
in digital filters?
2. List the errors which arise due to
quantization process.
3. Discuss the truncation error in quantization
process.
4. Write expression for variance of round-off
quantization noise.
5. What is sampling?
6. Define limit cycle Oscillations, and list
out the types.
7. When zero limit cycle oscillation and Over
flow limit cycle oscillation has occur?
8. Why? Scaling is important in Finite word
length effect.
9. What are the differences between Fixed and
Binary floating point number representation?
10. What is the error range for Truncation and
round-off process?
PART - B
1. The output of an A/D is fed through a
digital system whose system function is
H(Z)=(1-_)z /(z-_), 0<_<1.Find the output noise power of the
digital system. (8)
2. The output of an A/D is fed through a
digital system whose system function is
H(Z)=0.6z/z-0.6. Find the output noise power of
the digital system=8 bits (8)
3. Discuss in detail about quantization effect
in ADC of signals. Derive the expression for Pe(n) and SNR. (16)
4 a. Write short notes on limit cycle
oscillation (8)
b. Explain in detail about signal scaling (8)
5. A digital system is characterized by the
difference equation
Y(n)=0.95y(n-1)+x(n).determine the dead band of
the system when x(n)=0 and y(-1)=13. (16)
6. Two first order filters are connected in
cascaded whose system functions of theIndividual sections are H1(z)=1/(1-0.8z-¹ ) and
H2(z)=1/(1-0.9z¹ ).Determine the Over all output noise power. (16)
UNIT-IV: POWER SPECTRUM ESTIMATION
TWO MARKS
1. What is the need for spectral estimation?
2. How can the energy density spectrum be
determined?
3. What is autocorrelation function?
4. What is the relationship between
autocorrelation and spectral density?
5. Give the estimate of autocorrelation
function and power density for random signals?
6. Obtain the expression for mean and variance
for the autocorrelation function of random signals.
7. Define period gram.
PART - B
1. Explain how DFT and FFT are useful in power
spectral estimation. (10)
2. Explain Power spectrum estimation using the Bartlett
3. Obtain the mean and variance of the
averaging modified period gram estimate. (16)
4. How is the Blackman and Turkey
Periodogram? (10)
5. Derive the mean and variance of the power
spectral estimate of the Blackman and Turkey
6. What are the limitations of non-parametric
methods in spectral estimation? (8)
7. How the parametric methods overcome the
limitations of the non-parametric methods? (10)
UNIT-V: DIGITAL SIGNAL PROCESSORS
TWO MARKS:
1. What are the factors that influence the
selection of DSPs.
2 .What are the advantages and disadvantages of
VLIW architecture?
3. What is pipelining? and What are the stages
of pipelining?
4. What are the different buses of TMS 320C5x
processor and list their functions
5. List the various registers used with ARAU.
6. What are the shift instructions in TMS 320
C5x.
7. List the on-chip peripherals of C5x
processor.
PART - B
1. Explain in detail about the applications of
PDSP (10)
2. Explain briefly:
(i). Von Neumann architecture (5)
(ii). Harvard architecture (5)
(iii).VLIW architecture (6)
3. Explain in detail about
(i). MAC unit (8 )
(ii). Pipelining (8)
4. Draw and explain the architecture of TMS
320C5x processor (16)
5. Explain in detail about the Addressing modes
of TMS 320C50 (16)
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EEE ENGINEERING NOTES
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