Interview Questions on DSP - Open Thread - Please Contribute

dsp interview questions and answer

Hi
Time and frequency are two important aspects in which time and frequency are the inverse of each other.Hence if u have a small frequency it is spread out in large time and vice versa. Just u can analyze a time frequency plot.
So when we try to analyze non stationary signals these values continuously change and the properties of FFT do not hold for non stationary signals for which u need to go to either Short term Fourier trnasform or the wavelet analysis.
Each has it's own adv and disadv.
I have a good HTML on this issue.It gives a good introduction to the topic.

cheers
srinivas

interview questions + dsp

pls review this.

How toget a magnitude response of a quantized filter.
Any noise estimation has to be done??

cheers
srinivas

dsp basic questions

What is the basic difference blw FIR and IIR filters?
basic difference is FIR has liner phase response,where has IIR filter has nonlinear phase response.
why we use DCT extensilvely in compression?
DCT has excellent energy compaction property, for highly correlated input it give excellent energy compaction similar to KL transform.
why after DCt we use a zig zag manner for run length coding?
to convert to 2d to 1d data for run lenth coding, zig-zag is prefered because it scan the 2d data from low frequency to high frequency coef.
what is the special about minimum phase filter ?
minimum phase system has both poles and zeors reside in side unit circle, these are basically used for
compensating channel impairments.
"differences b/w butterworth, chebyshev, elliptical filter and advantages/disadvantages of each"?
butter worth -monotonic response in pass band and stop band.
chebyshev-1 ripple in pass band, and monotonic in stop band.
chebyshev-2 monotonic in passband ripple in stop band.
elliptic- ripple response both in passband &stop band.
for given set of parameters we can achive minimum transistion band width with elliptic filter , other way
we can implement with fewer number of coef than other methods

dsp questions

how can you compute fourier transform form Z-transform ?

Why IIR filters doesnt have Linear phase?

Can IIR filters be Linear phase? how to make it linear Phase?

What is the advantage of a Direct form II FIR over fom I?

Tell some thing about Interpolation and decimation?

What is Interpolation and decimation filters and why we need it?

FFT is in complex domain, how to use it in real life signals optimally?

what is the simplest high pass filter ? write the equation?

interview questions signal processing

what is the difference between DFT and DTFT?

what do u mean by spectral resolution?

how do u reduce spectral leakage?

basic dsp questions

how can you compute fourier transform form Z-transform ?

z =r*e(-iw) when r=1 Z-transform converges to discrete Fourier tranform.
Why IIR filters doesnt have Linear phase?.
Liner phase IIR filter cannot physically realizable , its unstable.

Can IIR filters be Linear phase? how to make it linear Phase?
Idealy Physically realizable doesnt have linear phase, but we can implement IIR filter with linear phase response in passband. (refer Bessel series Approx)

What is the advantage of a Direct form II FIR over fom I?
i think Direct form -2 take less memory (not sure)

Tell some thing about Interpolation and decimation?
Intepolation basically filling missing samples,
decimation basically reducing the sample rate.

What is Interpolation and decimation filters and why we need it?
interpolation for reconstruction and for sample rate up conversion.
deciamtion filter sample rate down conversion.

FFT is in complex domain, how to use it in real life signals optimally?
use two diiferent buffers for real & complex

what is the simplest high pass filter ? write the equation?
give me some precise more details
Hp= 1- Lp

Added after 5 minutes:

what is the difference between DFT and DTFT?

DFT = spectrum of DFT also discrete in nature,where as spectrum of DTFT is continuous.

what do u mean by spectral resolution?

i think its separetion of two signal in frequency domain.
how do u reduce spectral leakage?

By incresing the window lenth in time domain we can reduce spectral leakage.

Added after 12 minutes:

Why is FFT faster than DFT? what is the actual concept behind this?
FFT is an algorithm to implement DFT , FFT is not at all a tranform,
if u implement Directly it take (N^2) complex Multiplications and (N^2 -N) complex additions , where as FFT will Nlog2(N) complex Mul & additions

dsp viva questions

whats basic difference b/w winer filter and kalman filter and lms filter

Added after 5 minutes:

pls give me some points

signal processing based interview questions

What is the application fo Cross correlation and Auto Correlation?

What is Auto Regressive Model? How is the order of auto regressive model is decided?

What is the difference between equiripple filter and FIR filter?

interview questions digital filters

What is the application fo Cross correlation and Auto Correlation?

Cross correlation is used to find the similarities of two signals if its +1 or -1 it means its highly correlated and 0 signifies signals are uncorrelated


What is the difference between equiripple filter and FIR filter?

Equiripple filter means it has eual number of ripples in pass band and stop band
and its one of methos to implement filter design.
FIR filter is finate impluse response filter

interview questions dsp

1. Under what conditions is the available bandwidth of a digital system
Fs Hz instead of Fs/2 Hz?

2. What's the difference between an FFT and a DFT?

3. What two PSK modulation orders differ exactly by a factor of two
in spectral efficiency?

4. How does polyphase filtering save computations in a decimation filter?

5. How does polyphase filtering save computations in an interpolation filter?

6. Suppose we have a system with transfer function

H(z) = 1 / ((z - 1.1)*(z - 0.9)).

Is the system stable or unstable?

dsp objective interview questions

"What is the basic difference between digital and analog filter"

audio processing interview questions

what are the fourier series and fourier transforms and where we use them.

basic difference b w fir and iir filters?

helios said:

how can you compute fourier transform form Z-transform ?

Why IIR filters doesnt have Linear phase?

Can IIR filters be Linear phase? how to make it linear Phase?

What is the advantage of a Direct form II FIR over fom I?

Tell some thing about Interpolation and decimation?

What is Interpolation and decimation filters and why we need it?

FFT is in complex domain, how to use it in real life signals optimally?

what is the simplest high pass filter ? write the equation?

Click to expand...

Interpolation and decimation are tools in multirate signal processing

Added after 4 minutes:

both are nothing but up and down sampling....

Added after 3 minutes:

convoultion is a simple mathematical operation with any two signals...
if it is between X and Y it is called as crosscorrelation
if it is between X at time t1 and with same X at time t2 then it is called as autocorrelation

viva questions in digital signal processing

Hi, good topic thanks


'' Why we use the time-frq distribution? ''

We use it when our signal is nonstationary. This distribution allow us to know the disrtibution of the energy in both time and frq domain, so we can extract the instantaneous frq easily

dsp q interview

Where are IIR filters used? What are their applications?

In IIR filter, what is infinite?

dsp jobs on-site question

aashutosh said:

Where are IIR filters used? What are their applications?

In IIR filter, what is infinite?

Click to expand...

it means its impulse response is infinite over time........

dsp qustions interveiw

what's TFR ? TFR is time - frequencsy representation it's used to sho wus the distribution of the energy in the time domain and the frequency domaine alos

why? It's used for the non-statinnay signals, like voice signal, sismic signal, bimédical singals...

objective questions on digital signal processing

Does "zero padding" improve FFT resolution?

what is the disadvantage of bandpass sampling?

interview questions+ digital signal processing

chickoos said:

Does "zero padding" improve FFT resolution?

what is the disadvantage of bandpass sampling?

Click to expand...

plz try to answer

dsp technical interview questions

chickoos said:

Does "zero padding" improve FFT resolution?

Click to expand...

Answer: No, because resolution is determined by the length of
observation interval, and zero padding does not increase this
length

Refer
http://home.eng.iastate.edu/~julied/classes/ee524/LectureNotes/l5.pdf