# Multiple Choice Questions and Answers on Digital Signal Processing(Part-3)

1)   Two vectors a, b are orthogonal if

a. <a,b> = 0
b. <a,b> = <a,b>
c. <a,b> = 1
d. <a,b> = – <a,b>

2)   One dimensional signal is a function of

a. Multiple independent variables
b. Single independent variable
c. Multiple dependent variables
d. Single dependent variable

3)   Superposition of signals in a linear system refers to the

a. Output that is product of all the signals
b. Output that is sum of all the signals
c. Output that is of highest amplitude of all the signals
d. Output that is of largest spectrum of all the signals

ANSWER: (b) Output that is sum of all the signals

4)   The scaling of a sequence x[n] by a factor α is given by

a. y[n] = α [x[n]]2
b. y[n] = α x[n2]
c. y[n] = α x[n]
d. y[n] = x[n]x[-n]

ANSWER: (c) y[n] = α x[n]

5)   DFT is applied to

a. Infinite sequences
b. Finite discrete sequences
c. Continuous infinite signals
d. Continuous finite sequences

6)   The filtering is performed using DFT using

1) Limited size or blocks of data
2) Small memory size
3) Large memory size
4) Large segments of data

a. 1, 2 and 3 are correct
b. 3 and 4 are correct
c. 1 and 2 are correct
d. All the four are correct

ANSWER: (c) 1 and 2 are correct

7)   In Overlap-Add Method with linear convolution of a discrete-time signal of length L and a discrete-time signal of length M, for a length N, zero padding should be of length

a. L, M > N
b. L, M = N
c. L, M < N
d. L, M < N2

ANSWER: (c) L, M < N

8)   Discrete cosine transforms (DCTs) express a function or a signal in terms of

a. Sum of cosine functions oscillating at different frequencies
b. Sum of cosine functions oscillating at same frequencies
c. Sum of cosine functions at different sampling intervals
d. Sum of cosine functions oscillating at same sampling intervals

ANSWER: (a) Sum of cosine functions oscillating at different frequencies

9)   A system is said to be unstable if

a. None of the poles of its transfer function is shifted to the right half of s-plane
b. At least one zero of its transfer function is shifted to the right half of s-plane
c. At least one pole of its transfer function is shifted to the right half of s-plane
d. At least one pole of its transfer function is shifted to the left half of s-plane

ANSWER: (c) At least one pole of its transfer function is shifted to the right half of s-plane

10)   A system is said to be marginally unstable if

a. None of its zeros of its transfer function lies on the jω axis of s-plane
b. At least one zero of its transfer function lies on the jω axis of s-plane
c. None of its poles of its transfer function lies on the jω axis of s-plane
d. At least one pole of its transfer function lies on the jω axis of s-plane

ANSWER: (d) At least one pole of its transfer function lies on the jω axis of s-plane

11)   The nonlinear difference equations are solved using

a. Iterative method
b. Cobweb model
c. Phase diagram
d. Power series method

12)   Correlation is used for

1) Computation of average power in waveforms
2) Climatography
3) Identification of binary code word in PCM systems
4) Quantization

a. 1, 2 and 3 are correct
b. 1 and 2 are correct
c. 2 and 3 are correct
d. All the four are correct

ANSWER: (a) 1, 2 and 3 are correct

13)   The Chebyshev filters have

1) Flat pass band
2) Flat stop band
3) Equiripple pass band
4) Tapering stop band

a. 1 and 2 are correct
b. 2 and 4 are correct
c. 2 and 3 are correct
d. All the four are correct

ANSWER: (c) 2 and 3 are correct

14)   The Elliptic filters have

1) Flat pass band
2) Flat stop band
3) Equiripple pass band
4) Equiripple stop band

a. 1 and 2 are correct
b. 3 and 4 are correct
c. 2 and 3 are correct
d. All the four are correct

ANSWER: (b) 3 and 4 are correct

15)   The effects caused due to finite word lengths are

1) Coefficient quantization error
3) Round off noise
4) Limit cycles
a. 1, 2 and 3 are correct
b. 1 and 3 are correct
c. 1 and 4 are correct
d. All the four are correct

ANSWER: (d) All the four are correct

16)   The error in the filter output that results from rounding or truncating calculations within the filter is called

a. Coefficient quantization error
c. Round off noise
d. Limit cycles

17)   Consider the assertions given below. Which among them is an advantage of FIR Filter?

a. Necessity of computational techniques for filter implementation
b. Requirement of large storage
c. Incapability of simulating prototype analog filters
d. Presence of linear phase response

ANSWER: (d) Presence of linear phase response

18)   For a linear phase filter, if Z1 is zero then what would be the value of Z1-1 or 1/ Z1?

a. Zero
b. Unity
c. Infinity
d. Unpredictable

19)   In FIR filter design, which among the following parameters is/are separately controlled by using Kaiser window?

a. Order of filter (M)
b. Transition width of main lobe
c. Both a and b
d. None of the above

ANSWER: (c) Both a and b

20)   Which window function is also regarded as ‘Raised-cosine window’?

a. Hamming window
b. Hanning window
c. Barlett window
d. Blackman window

21)   In Barlett window, the triangular function resembles the tapering of rectangular window sequence _______ from the middle to the ends.

a. linearly
b. elliptically
c. hyperbolically
d. parabolically

22)   In Gibb’s phenomenon, the ringing effect is predominantly present near the ______ .

a. bandgap
b. bandedge
c. bandwidth
d. bandshell

23)   How is/are the roundoff errors reduced in the digital FIR filter?

b. By rounding the results after acquiring the final sum
c. Both a and b
d. None of the above

ANSWER: (c) Both a and b

24)   In linear phase realization, equal valued coefficients are taken common for reducing the requisite number of ________.

b. subtractors
c. multipliers
d. dividers

25)   Which filters exhibit their dependency upon the system design for the stability purpose?

a. FIR
b. IIR
c. Both a and b
d. None of the above

26)   In FIR filters, which among the following parameters remains unaffected by the quantization effect?

a. Magnitude Response
b. Phase Characteristics
c. Both a and b
d. None of the above

27)   In the frequency response characteristics of FIR filter, the number of bits per coefficient should be _________in order to maintain the same error.

a. Increased
b. Constant
c. Decreased
d. None of the above

28)   In cascade form of realization, how many bits should be used to represent the FIR filter coefficients in order to avoid the quantization effect on filter coefficients?

a. 5 to 10
b. 12 to 14
c. 20 to 24
d. 28 to 40

29)   Consider the assertions (steps) given below. Which among the following is a correct sequence of designing steps for the sampling rate converters?

A. Computation of decimation/interpolation factor for each stage.
B. Clarification of anti-aliasing / anti-imaging filter requirements.
C. Designing of filter at each stage.
D. Calculation of optimum stages of decimation/ interpolation yielding maximum efficient implementation.

a. A, B, C, D
b. C, A, D, B
c. D, A, B, C
d. B, D, A, C

ANSWER: (d)  B, D, A, C

30)   For designing a multirate LPF with passband 0 to 50 Hz, stopband 60 to 280 Hz, stopband deviation 0.001, passband deviation 0.01 and sampling frequency (fs) = 400 Hz, what would be the value of normalized transition width?

a. 0.025 Hz
b. 1.25 Hz
c. 1.50 Hz
d. 2.6 Hz

31)   In polyphase filters, the subfilters which share a common delay line results in the reduction of the storage requirement by factor ______

a. 1
b. 2
c. 3
d. 4

32)   How is the operating level of sampling rate for the subfilters involved in the polyphase filters?

a. Low
b. Moderate
c. High
d. None of the above

33)   In polyphase filter, which kind of realization is/are adopted for three subfilters possessing coefficients?

b. Parallel
c. Direct
d. All of the above

34)   How is the sampling rate conversion achieved by factor I/D?

a. By increase in the sampling rate with (I)
b. By filtering the sequence to remove unwanted images of spectra of original signal
c. By decimation of filtered signal with factor D
d. All of the above

ANSWER: (d) All of the above

35)   Program Sequence plays a crucial role in maintaining the track of ___________

a. Program counter increment
b. Conditional branching & looping
c. Subroutine & interrupt handling
d. All of the above

ANSWER: (d) All of the above

36)   In DSP Processor, what kind of queuing is undertaken/executed through instruction register and instruction cache?

a. Implicate
b. Explicate
c. Both a and b
d. None of the above

37)   In TMS 320 C6x processor architecture, which functional unit is adopted for transferring the data from register to and from control register?

a. L2
b. M2
c. S2
d. D2

38)   In TMS 320 C6x processor architecture, which operation/s is/are performed by ‘M’ functional unit?

a. Bit expansion
b. Bit interleaving & deinterleaving
c. Rotation & Variable shifting
d. All of the above

ANSWER: (d) All of the above

39)   In C6X processor, which external device/s get/s acquire/s an interface support by EMIF peripheral?

a. Synchronous burst
b. Asynchronous devices
c. Externally shared memory devices
d. All of the above

ANSWER: (d) All of the above

40)   Which peripheral on C 6 X processor allows buffering of serial samples in memory by port automatically & especially with an assistance of EDMA controller?