# Multiple Choice Questions and Answers on Digital Signal Processing(Part-2)

**1) The cost of the digital processors is cheaper because**

**a.** Processor allows time sharing among a number of signals

**b.** The hardware is cheaper

**c.** Require less maintenance

**d.** Less power consumption

**ANSWER:(a) Processor allows time sharing among a number of signals**

**2) The operations that may be performed on vectors in Euclidean Space are**

1) Inner product, distance between vectors

2) Norm of a vector, orthogonal vectors

3) Orthonormal functions

4) Vector division

**a.** 1, 2 and 3 are correct

**b.** 1 and 2 are correct

**c.** 1, 2 and 4 are correct

**d.** All the four are correct

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

**3) The norm or length of a signal is given by**

**a.** The square of the energy of the signal

**b.** The square root of the energy of the signal

**c.** The inverse of the energy of the signal

**d.** The cube root of the energy of the signal

**ANSWER: (a) The square root of the energy of the signal**

**4) The principle of Gram-Schmidt Orthogonalization (GSO) states that, any set of M energy signals can be expressed as**

**a.** Summation of N ortho normal basis functions, where N ≤ M.

**b.** Linear combinations of N ortho normal basis functions, where N ≤ M.

**c.** Product of logarithmic combinations of N ortho normal basis functions, where N ≤ M.

**d.** Product of inverse squares of N ortho normal basis functions, where N ≤ M.

**ANSWER: (b) Linear combinations of N ortho normal basis functions, where N ≤ M.**

**5) A signal x[n] is anti symmetric or odd when**

**a.** x[-n] = x[n] • x[n]

**b.** x[n] = -x[n]

**c.** x[n] = [x[n]]^{2}

**d.** x[-n] = -x[n]

**ANSWER: (d) x[-n] = -x[n]**

**6) Time shifting of discrete time signal means**

**a.** y[n] = x[n-k]

**b.** y[n] = x[-n-k]

**c.** y[n] = -x[n-k]

**d.** y[n] = x[n+k]

**ANSWER:(a) y[n] = x[n-k]**

**7) Time reversal of a discrete time signal refers to**

**a.** y[n] = x[-n+k]

**b.** y[n] = x[-n]

**c.** y[n] = x[-n-k]

**d.** y[n] = x[n-k]

**ANSWER: (b) y[n] = x[-n]**

**8) Causal systems are the systems in which**

**a.** The output of the system depends on the present and the past inputs

**b.** The output of the system depends only on the present inputs

**c.** The output of the system depends only on the past inputs

**d.** The output of the system depends on the present input as well as the previous outputs

**ANSWER: (a) The output of the system depends on the present and the past inputs**

**9) The basic properties of DFT includes**

1) Linearity

2) Periodicity

3) Circular symmetry

4) Summation

**a.** 1, 2 and 3 are correct

**b.** 1, 2 and 4 are correct

**c.** 1 and 3 are correct

**d.** All the four are correct

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

**10) Padding of zeros increases the frequency resolution.**

**a.** True

**b.** False

**ANSWER: (b) False**

**11) Circular shift of an N point is equivalent to**

**a.** Circular shift of its periodic extension and its vice versa

**b.** Linear shift of its periodic extension and its vice versa

**c.** Circular shift of its aperiodic extension and its vice versa

**d.** Linear shift of its aperiodic extension and its vice versa

**ANSWER: (b) Linear shift of its periodic extension and its vice versa**

**12) The circular convolution of two sequences in time domain is equivalent to**

**a.** Multiplication of DFTs of two sequences

**b.** Summation of DFTs of two sequences

**c.** Difference of DFTs of two sequences

**d.** Square of multiplication of DFTs of two sequences

**ANSWER: (a) Multiplication of DFTs of two sequences**

**13) For the calculation of N- point DFT, Radix -2 FFT algorithm repeats**

**a.** 2(N Log2 N) stages

**b.** (N Log2 N)^{2}/2 stages

**c.** (N Log2 N)/2 stages

**d.** (N Log2(2 N))/2 stages

**ANSWER: (c) (N Log2 N)/2 stages**

**14) Radix – 2 FFT algorithm performs the computation of DFT in**

**a.** N/2Log2 N multiplications and 2Log2 N additions

**b.** N/2Log2 N multiplications and NLog2 N additions

**c.** Log2 N multiplications and N/2Log2 N additions

**d.** NLog2 N multiplications and N/2Log2 N additions

**ANSWER: (b) N/2Log2 N multiplications and NLog2 N additions**

**15) The overlap save method is used to calculate**

**a.** The discrete convolution between a sampled signal and a finite impulse response (FIR) filter

**b.** The discrete convolution between a sampled signal and an infinite impulse response (IIR) filter

**c.** The discrete convolution between a very long signal and a finite impulse response (FIR) filter

**d.** The discrete convolution between a very long signal and a infinite impulse response (IIR) filter

**ANSWER: (c) The discrete convolution between a very long signal and a finite impulse response (FIR) filter**

**16) Overlap-Add Method Deals with principles that **

**a.** The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length L + M – 1

**b.** The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length L + M

**c.** The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length 2L + M – 1

**d.** The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length 2L + 2M – 1

**ANSWER:(a) The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length L + M – 1**

**17) ROC does not have**

**a.** zeros

**b.** poles

**c.** negative values

**d.** positive values

**ANSWER: (b) poles**

**18) Damping is the ability of a system **

**a.** To support oscillatory nature of the system’s transient response

**b.** To oppose the continuous nature of the system’s transient response

**c.** To oppose the oscillatory nature of the system’s transient response

**d.** To support the discrete nature of the system’s transient response

**ANSWER: (c) To oppose the oscillatory nature of the system’s transient response**

**19) The condition for a system to be causal is**

**a.** All poles of its transfer function must be left half of s-plane

**b.** All poles of its transfer function must be right half of s-plane

**c.** All zeros of its transfer function must be right half of s-plane

**d.** All zeros of its transfer function must be left half of s-plane

**ANSWER:(b) All poles of its transfer function must be right half of s-plane**

**20) The condition for a system to be stable is**

**a.** All poles of its transfer function lie on the left half of s-plane

**b.** All poles of its transfer function must be right half of s-plane

**c.** All zeros of its transfer function must be right half of s-plane

**d.** All zeros of its transfer function must be left half of s-plane

**ANSWER: (a) All poles of its transfer function lie on the left half of s-plane**

**21) Partial fraction method involves**

**a.** Allotting coefficients

**b.** Dividing the numerator by denominator to get fractions

**c.** Dividing single fraction into parts

**d.** None of the above

**ANSWER: (c) Dividing single fraction into parts**

**22) The factors formed for partial fraction are a combination of**

1) Linear factors

2) Irreducible quadratic factors

3) Square roots

4) Cube roots

**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: (b) 1 and 2 are correct**

**23) For a partial fraction method to be followed,**

1) The degree of the numerator must be more than the degree of the denominator.

2) The factors formed for partial fraction are a combination of Linear factors and Irreducible quadratic factors.

3) The degree of the numerator must be less than the degree of the denominator.

4) The factors formed for partial fraction are a combination of Linear factors and Square roots.

**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:(c) 2 and 3 are correct**

**24) The partial fraction of x ^{2}+1/x(x-1)^{2} is**

**a.** 1/ (x-1) + 2/(x-1)^{2} – 1/x

**b.** 1/ (x-1) + 2/(x-1)^{2} – 3/x

**c.** 1/ (x-1) + 2/(x-1)^{2} – 3/x^{2}

**d.** 1/ (x+1) + 2/(x+1)^{2} – 1/x

**ANSWER: (a) 1/ (x-1) + 2/(x-1) ^{2} – 1/x**

**25) The impulse invariant method is obtained by**

**a.** Sampling the impulse response of an equivalent analog filter

**b.** Taking backward difference for the derivative

**c.** Mapping from s-domain to z-domain

**d.** Approximation of derivatives

**ANSWER: (a) Sampling the impulse response of an equivalent analog filter**

**26) The transformation technique in which there is one to one mapping from s-domain to z-domain is**

**a.** Approximation of derivatives

**b.** Impulse invariance method

**c.** Bilinear transformation method

**d.** Backward difference for the derivative

**ANSWER: (c) Bilinear transformation method**

**27) The frequency warping is referred as**

1) lower frequencies in analog domain expanded in digital domain

2) lower frequencies in digital domain expanded in analog domain

3) non linear mapping

4) compression of higher frequencies

**a.** 1, 3 and 4 are correct

**b.** 2 and 4 are correct

**c.** 2 and 3 are correct

**d.** All the four are correct

**ANSWER: (a) 1, 3 and 4 are correct**

**28) The magnitude response of Butterworth filter has**

1) Flat stop band

2) Flat pass band

3) Tapering 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: (a) 1 and 2 are correct**

**29) In the cascaded form of realisation, the polynomials are factored into**

**a.** a product of 1st-order and 2nd-order polynomials

**b.** a product of 2nd-order and 3rd-order polynomials

**c.** a sum of 1st-order and 2nd-order polynomials

**d.** a sum of 2nd-order and 3rd-order polynomials

**ANSWER: (a) a product of 1st-order and 2nd-order polynomials**

**30) Parallel form of realisation is done in**

**a.** High speed filtering applications

**b.** Low speed filtering applications

**c.** Both a and b

**d.** None of the above

**ANSWER: (a) High speed filtering applications**

**31) A partial-fraction expansion of the transfer function in Z ^{-1} leads to**

**a.** The parallel form II structure

**b.** The parallel form I structure

**c.** Cascaded structure

**d.** None of the above

**ANSWER: (b) The parallel form I structure**

**32) A direct partial-fraction expansion of the transfer function in Z leads to**

**a.** The parallel form II structure

**b.** The parallel form I structure

**c.** Cascaded structure

**d.** None of the above

**ANSWER: (a) The parallel form II structure**

**33) Basically, group delay is the delayed response of filter as a function of ________.**

**a.** Phase

**b.** Amplitude

**c.** Frequency

**d.** All of the above

**ANSWER: (c) Frequency**

**34) A filter is said to be linear phase filter if the phase delay and group delay are _______**

**a.** High

**b.** Moderate

**c.** Low

**d.** Constant

**ANSWER: (d) Constant**

**35) Which among the following has/have a provision to support an adaptive filtering mechanism?**

**a.** IIR

**b.** FIR

**c.** Both a and b

**d.** None of the above

**ANSWER: (c) Both a and b**

**36) Which is/are the correct way/s for the result quantization of an arithmetic operation?**

**a.** Result Truncation

**b.** Result Rounding

**c.** Both a and b

**d.** None of the above

**ANSWER: (c) Both a and b**

**37) In direct form realization for an interpolator, which among the following generates an intermediate signal? **

**a.** Upsampler

**b.** Downsampler

**c.** Anti-imaging filter

**d.** Anti-aliasing filter

**ANSWER: (a) Upsampler**

**38) To change the sampling rate for better efficiency in two or multiple stages, The decimation and interpolation factors must be _________unity.**

**a.** Less than

**b.** Equal to

**c.** Greater than

**d.** None of the above

**ANSWER: (c) Greater than**

**39) Which address/es is/are generated by Program Sequences? **

**a.** Data Address

**b.** Instruction Address

**c.** Both a and b

**d.** None of the above

**ANSWER: (b) Instruction Address**

**40) In DAGs, which register/s provide/s increment or step size for index register especially during the register move?**

**a.** Index Register

**b.** Length & Base Register

**c.** Modify Register

**d.** All of the above

**ANSWER: (c) Modify Register**