Digital Signal Processing (DSP) Viva Questions

DIGITAL SIGNAL PROCESSING (DSP) VIVA QUESTIONS:

1. What is sampling theorem?
2. What do you mean by process of reconstruction.
3. What are techniques of reconstructions.
4. What do you mean Aliasing? What is the condition to avoid aliasing for sampling?
5. Write the conditions of sampling.
6. How many types of sampling there?
7. Explain the statement-
t= 0:0.000005:0.05
8. In the above example what does colon (: ) and semicolon (; ) denotes.
9. What is a) Undersampling b) nyquist plot c) Oversampling.
10. Write the MATLAB program for Oversampling.
11. What is the use of command ‘legend’?
12. Write the difference between built in function, plot and stem describe the function.
13. What is the function of built in function and subplot?
14. What is linear convolution?
15. Explain how convolution syntax built in function works.
16. How to calculate the beginning and end of the sequence for the two sided controlled output?
17. What is the total output length of linear convolution sum.
18. What is an LTI system?
19. Describe impulse response of a function.
20. What is the difference between convolution and filter?
21. Where to use command filter or impz, and what is the difference between these two?
22. What is the use o function command ‘deconv’?
23. What is the difference between linear and circular convolution?
24. What do you mean by statement subplot (3,3,1).
25. What do you mean by command “mod” and where it is used?
26. What do you mean by Autocorrelation and Crosscorrelation sequences?
27. What is the difference between Autocorrelatio and Crsscorrelation.
28. List all the properties of autocorrelation and Crosscorrelaion sequence.
29. Where we use the inbuilt function ‘xcorr’ and what is the purpose of using this function?
30. How to calculate output of DFT using MATLAB?
31. What do you mean by filtic command, explain.
32. How to calculate output length of the linear and circular convolution.
33. What do you mean by built in function ‘fliplr’ and where we need to use this.
34. What is steady state response?
35. Which built in function is used to solve a given difference equation?
36. Explain the concept of difference equation.
37. Where DFT is used?
38. What is the difference between DFT and IDFT?
39. What do you mean by built in function ‘abs’ and where it is used?
40. What do you mean by phase spectrum and magnitude spectrum/ give comparison.
41. How to compute maximum length N for a circular convolution using DFT and IDFT.(what is command).
42. Explain the statement- y=x1.*x2
43. What is FIR and IIR filter define, and distinguish between these two.
44. What is filter?
45. What is window method? How you will design an FIR filter using window method.
46. What are low-pass and band-pass filter and what is the difference between these two?
47. Explain the command – N=ceil(6.6*pi/tb)
48. Write down commonly used window function characteristics.
49. What is the matlab command for Hamming window? Explain.
50. What do you mea by cut-off frequency?

Q1.- Classify signals.
Ans1.
Continuous-time, continuous amplitude (Analog Signals)
Discrete time, continuous amplitude
Continuous time, discrete amplitude
Discrete-time, discrete-amplitude
Q2.-What is the use of Random Signals?
Ans2. Random signals are used to test dynamic response statistically for very small amplitudes and time-duration.
Q3.- Classify Systems.
Ans3. Linear, stable and time-invariant.
Q4.-What do you mean by aliasing in digital signal processing? How it can be avoided?
Ans4. Aliasing refers to an effect due to which different signals become indistinguishable. It also refers to distortion in the reconstructed signal when it is reconstructed from the original continuous signal.
To avoid aliasing we can simply filter out the high frequency components of the signal by using anti-aliasing filter like optical anti-aliasing filter.
Q5. – What are the differences between a microprocessor and a DSP processor?
Ans5. DSP processors are featured to support high performance and repeatitive and intensive tasks whereas microprocessors are not application specific and they are designed to process control-oriented tasks.
Q6. – What is the convolution?
Ans6. Convolution is the technique of adding two signals in time domain. We can also do this quite easily by changing the domain of signals from time domain to frequency domain using Fast Fourier Transform (FFT).
Q7.- What is FFT?
Ans7. FFT is a fast way to calculate Discrete Fourier Transform (DFT). It is much more efficient then DFT and require less number of coding lines. Due to FFT several kind of techniques are feasible.
Q8.- What is the advantage of a Direct form II FIR over fom I?
Ans8. Direct Form II FIR filters requires half the number of delay units as much as used by Form I.
Q9.- What is interpolation and decimation?
Ans9. Interpolation is the process of increasing the sample rate in dsp whereas decimation is the opposite of this that is, it is the process of decreasing the sample rate in dsp.
10.- Difference between DFT and DTFT.
Ans10.

DFT	DTFT
1-Limited number of samples of periodic signal	1-unlimited number of samples.
2- input is always periodic	2-input may not always be periodic
3- physically realizable	3- mathematically precise
4- frequency becomes discrete	4- frequency is continuous

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