Andrea
  • Member for 6 years, 2 months
  • Last seen this week
Do integration/differentiation processes work as simple filters?
4 votes

Yes, integration and differentiation can be linear filters. You can start from laplace properties that say: $ \int_{0}^{t} {x(t)dt} \longrightarrow \frac{X(s)}{s} \\ \frac{d}{dt}x(t) \longrightarrow ...

View answer
How to conclude LTI, causality and BIBO stability of a system represented by a differential equation?
Accepted answer
4 votes

I take your equation: $\frac{d^2y}{dt^2}-3\frac{dy}{dt}+2y(t)=x(t)$ Laplace transform will be: $ s^2Y(S) - 3sY(S) +2Y(s) = X(s) $ Now I can find transfer function: $H(s) \triangleq \frac{Y(s)}{X(s)}$...

View answer
When applying a bandpass filter designed in Matlab's DSP system toolbox, is it necessary to do any normalization?
1 votes

Note that you are cutting a lot of signal frequencies in the transition from 10Hz to 200Hz (look the attenuation in the frequency response of the filter), consider to use lowpass filter or to change ...

View answer
How to remove lines from captcha image which are acting as noise using java?
1 votes

I worked on this problem some time ago, my solution was to compress the image with wavelet transform with an opportune coefficient that depends on captcha type that I choose with some expermients. ...

View answer
What do we call the areas with "1" in a binary image
1 votes

This problem born when you use pixel intensity as physical mass, for example to calculate mass center or inertia moments, in this case the background should be 0 and object should be 1. Btw your ...

View answer
Evauating response to $x(n) = \sin{2\pi\frac{1}{4}n}$ given the system function
1 votes

You can start from z-transform of sine: $ Z[sin(2\pi f n)\cdot u(n)](z)= \frac{z \cdot sin(2 \pi f)}{z^2-2z \cdot cos(2 \pi f)+1}$ For your signal you have $f=1/4$ and substituting you obtain: $ X(...

View answer
Butterworth filter for signal processing
1 votes

First of all when you work with MATLAB I suggest you to use a time axis t. [x,Fs] = audioread('go10.wav'); % to read the data t=(0:length(x)-1)/Fs; plot(t,x) ; % Now when you plot you can see the ...

View answer
What is the best approach to classify an image containing either text or image?
1 votes

The segment with text (I assume with a background) should contains text clearly visible from the background, then the text segment should have a lot of peaks in the transitions from text to background....

View answer
Creating odd harmonics without the fundamental
1 votes

The function should be something like this: SR=sampling rate T=duration in second of the output t=0:(1/SR):T x=your sin wave input X=fft(x) freq=index of max(mod(X)) from 0 to SR/2 (in [Hz]) ai=[1 1 ...

View answer
How to classify accelerometer data?
1 votes

You should know the orientation of the phone because the axis signum must be the same of the car motion. Assuming the axis signum is correct you can filter the accelerometer signal in lowpass, to ...

View answer
Band limited discrete signals division
0 votes

I've found an estimator that can work for a lot of similar situations, the idea is that you can rewrite the division: $$ x(t) = z(t) \cdot y(t) \tag1$$ The problem now is to estimate $ z(t) $ that ...

View answer
Proof of linearity
0 votes

This is a $5$ variables equation, each variable is an $x[n-i]$ or $y[n-i] $ and you have not to consider the time to prove linearity. Take the linear equation definition: $ \sum_{k=1}^N c_k \cdot ...

View answer
Is this two input discrete system linear?
0 votes

To be linear you must have a function $f$ that satisfy: $ f(a\overline {x_1} + b \overline{x_2}) = af(\overline{x_1})+ b f(\overline{x_2}) $ I define $ \overline{x}=\left [\begin{matrix}\overline{x}(...

View answer
Avarege of a photo and its brightness
Accepted answer
0 votes

In your question there is not a matrix because some elements are missing, I assume they are equal to $0$. This solution in MATLAB should works: syms a b c f=1/12*[ 0 , 0 , 0 , 0, 0; 0 , c , ...

View answer
Possible ways to determine the direction of moving object?
0 votes

If the image is clear mass center (like @goldrik suggests) is a good option otherwise you can use cross correlation and find its pitch to detect the distance and the direction of the second center ...

View answer
The model of noise in Image denoising problem
0 votes

A1: This is a noise composed by a lot of indipendet factors. For example an old camera made with an old technology makes an high noise on the photo caused by the imprecision of the various components. ...

View answer