# 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>

**ANSWER: (a) <a,b> = 0**

**2) One dimensional signal is a function of**

**a.** Multiple independent variables

**b.** Single independent variable

**c.** Multiple dependent variables

**d.** Single dependent variable

**ANSWER: (b) Single independent 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[n^{2}]

**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

**ANSWER: (b) Finite discrete 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 < N^{2}

**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

**ANSWER: (c) Phase diagram**

**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

2) Adder overflow limit cycle

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

**b.** Adder overflow limit cycle

**c.** Round off noise

**d.** Limit cycles

**ANSWER: (c) Round off noise**

**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 Z _{1} is zero then what would be the value of Z_{1}^{-1} or 1/ Z_{1}?**

**a.** Zero

**b.** Unity

**c.** Infinity

**d.** Unpredictable

**ANSWER: (a) Zero**

**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

**ANSWER: (b) Hanning 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

**ANSWER: (a) linearly**

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

**a.** bandgap

**b.** bandedge

**c.** bandwidth

**d.** bandshell

**ANSWER: (b) bandedge**

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

**a.** By representation of all products with double-length registers

**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 ________.**

**a.** adders

**b.** subtractors

**c.** multipliers

**d.** dividers

**ANSWER: (c) multipliers**

**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

**ANSWER:(b) IIR**

**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

**ANSWER: (b) Phase Characteristics**

**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

**ANSWER: (a) Increased**

**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

**ANSWER: (b) 12 to 14**

**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 (f _{s}) = 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

**ANSWER: (a) 0.025 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

**ANSWER: (c) 3**

**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

**ANSWER: (a) Low**

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

**a.** Cascade

**b.** Parallel

**c.** Direct

**d.** All of the above

**ANSWER: (b) Parallel**

**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

**ANSWER: (a) Implicate**

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

**a.** L_{2}

**b.** M_{2}

**c.** S_{2}

**d.** D_{2}

**ANSWER: (c) S _{2}**

**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?**

**a.** Boot Loader

**b.** HPI

**c.** EMIF

**d.** McBSP

**ANSWER:(d) McBSP**