# Fourier Analysis and Filtering

This set of MATLAB MCQs focuses on “Fourier Analysis and Filtering ”.

1. What is the output of the following code?

`buttord[2,1,3,4]`

a) Error
b) Returns order of the filer
c) 1
d) 0

2. What is the output of the following code?

`Buttord(1,2,3,4)`

a) 1
b) Syntactical Error
c) Frequency Error
d) Error

3. The order of the type 1 Chebyshev filter is obtained from the ________
a) cheb1ord()
b) chebord()
c) chebyord()
d) chebshev()

4. The cut-off frequency of the type-2 Chebyshev filter is produced by the ________
a) cheby2ord()
b) chebyord2()
c) chebyshevord2()
d) cheby2order()

5. The ellipord command is used for _________
a) FIR Filter design
b) IIR Filter design
c) Both IIR and FIR filter design
d) No such command

6. The freqz() command returns __________
a) No such command
b) A set of frequencies
c) Frequency Response
d) Phase plot

7. The fftfilt command filters data based on ____________
a) Convolution
b) Overlap save method
c) No such command

8. The bilinear transformation is done by the ________
a) bilin()
b) bilinear()
c) no such command
d) bilineartran()

9. The bilinear command returns column vectors.
a) True
b) False

10. In chebwin(L,r), what is the default value of r?
a) 150 dB
b) 90 dB
c) 100 dB
d) 110 dB

11. Butterworth and Low pass filters use _________
a) IIR and FIR Design
b) FIR and IIR Design
c) FIR Design
d) IIR Design

12. The result of the following code is

`p=dtft([1,2,3],3)`

a) Returns a 3-point D.T.F.T.
b) Returns a N-point D.T.F.T.
c) Returns a 3-point D.F.T.
d) Error

13. The above command will give

`A=fft((1,2,3),2)`

a) D,F,T after taking a truncated input
b) Yield a 2-point D.F.T.
c) Uses the Butterfly algorithm
d) Error

14. The fir1 command can be used to find _____________
a) High Pass Filters using IIR method
b) Low Pass Filters FIR method
c) Filters using Window Method
d) FIR filters using Window Method

15. The multiplication of two signal in time domain signifies _______
a) Convolution in time domain
b) Convolution in frequency (jw) domain
c) Multiplication in frequency (jw) domain
d) Nothing

16. The window function is used to __________
a) multiply it with the incoming signal
b) add it with the incoming signal
c) subtract it from the incoming signal
d) divide the incoming signal

17. The output of the following codes are

```i fft([1,2],2,2)
ii. fft([1,2],2)```

a) same
b) different
c) I will give error
d) ii wil give error

18. The butter() command takes in ________
a) Stopband attenuation
b) Order of the filter
c) Ripple frequency
d) Nothing

19. The blackmann(N) command returns a ___________
a) N-point periodic blackmann window
b) N+1-point periodic blackmann window
c) N+1-point periodic blackmann window
d) N-point symmetric blackmann window

20. The result of the following command is

`hamming[32]`

a) Error
b) A 32 point symmetric Hamming Window
c) A 33 point periodic Hamming Window
d) A 33 point Hamming Window

21. fft2 returns _________
a) a 2-d matrix
b) a 2-d D.F.T
c) a vector
d) No such command

22. What is the function of the unwarp command?
a) Generate smoother phase plots
b) Generate smoother gain plots
c) Generate smoother root locus
d) No such command

23. The default tolerance of the unwarp() function is ________
a) pi
b) 2*pi
c) pi/2
d) 0

24. The hamming command returns a ___________
a) matrix
b) row vector
c) column vector
d) no such command

25. What is the value of N while creating a 27 point Hamming window?
a) 28
b) 26
c) 14
d) 13