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# Greg Dionne

### MathWorks

145 total contributions since 2012

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Segmentation of audio signal.
If you have the Signal Processing Toolbox, buffer may be what you're after. Hope this helps! -Greg

2 meses ago | 0

RMS Function Returns NAN
It's likely you have NaN in your input, or your input is an empty vector. If you wish to exclude NaN values from computation, t...

2 meses ago | 0

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thd() in matlab workspace shows me an unexpected result, is anything wrong ?
The default window used when running the THD function has a wide rolloff which masks the second and third harmonics in your sign...

3 meses ago | 2

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Why this bandpass butterworth is unstable (while the corresponding low and high pass are stable)?
You will have better results if you use second-order sections. See the "Limitations" section of https://www.mathworks.com/help/...

3 meses ago | 1

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medfreq with delta-F threshold ?
From what I can tell your sinusoid is around ~895 Hz and has fairly clean second and third harmonics. So I took that as the sta...

3 meses ago | 0

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measure time from fft spectrogram
You can extract the time vector from the third output of the spectrogram function. [S,F,T,Pxx] = spectrogram(X,...) F is the...

3 meses ago | 0

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Fast Fourier Transform of the subtraction between a signal and the same signal but shifted
Circularly shifting in the time domain is equivalent to multiplying by a phase ramp in the frequency domain. The FFT of the va...

3 meses ago | 1

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How to get pairwise distance matrices from dynamic time warping dtw on a matrix of time series ?
Your signals look extremely well time-aligned (within a sample). Since you have NaN, I suppose you could just perform a weigh...

4 meses ago | 0

Warping window in "findsignal()" for dtw as TimeAlignment.
At the moment there are no warping constraints used in the FINDSIGNAL variant of DTW. I'm usually successful at coaxing it to...

4 meses ago | 0

FFT of Downsampled Signal
Hi Adam, If you have significant noise on the signal, then decimate(x,10) or resample(x,1,10) would be preferable. Your result...

4 meses ago | 1

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Making a video showing trajectories of particles
This should get you started: load Trajectories.mat hAxes = newplot; colors = lines(10); axis(hAxes,[0 1300 0 1100]) f...

4 meses ago | 0

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DSP TOOL BOX NOT WORKING Spectrum Analyzer For Two-Sided Power Spectrum
This worked for me: sin = dsp.SineWave('Frequency',100,'SampleRate',1000); sin.SamplesPerFrame = 1000; scope = dsp.SpectrumAn...

4 meses ago | 1

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Generating a sound that goes up and down in frequency - based on a vector of numbers
Hi Harriet, I'm glad you have the Signal Processing Toolbox and were successfully able to use vco, resample, and spectrogram to...

6 meses ago | 0

Weighted spline for calculating trajectory with lowest possible lateral acceleration
I'm not certain if I understood your question correctly, but you could try adapting the approach in the drivingScenario trajecto...

6 meses ago | 0

How to select matching records based on the differences in their detection time?
I think you want something like this(?): function [t1s, t2s] = szanto(t1, t2) % compute time vectors offset from first tim...

6 meses ago | 0

How to find the slope of phase data (between two points) which is uneven
You could try a combination of <https://www.mathworks.com/help/matlab/ref/unwrap.html unwrap> (to remove the jumps of your array...

10 meses ago | 0

Looking for a way to patch 44k polygons fast
Have you tried using just one patch? You can specify X and Y as matrices (this example taken from the doc page on <https://www....

10 meses ago | 0

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how to apply dynamic time wrapping
DTW(X,Y) can work on vectors of non-equal length. It will repeat elements in either X or Y so that the comparison is of the sam...

11 meses ago | 0

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How can I determine the diameter (inner and outer) of the ring profile?

11 meses ago | 0

Why does findchangepts doesn't work right?
If you have R2016b or later try: Fs = 100; [sst,f] = fsst(Ch9,Fs,kaiser(512,10)); fridge = tfridge(sst,f,10,'NumRidge...

11 meses ago | 1

Time response of the voltage
Most of the documentation for the bilevel measurements panel can be found here: <https://www.mathworks.com/help/simulink/ug/bile...

alrededor de 1 año ago | 0

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ismember runs too slow (others have asked similar questions)
Looks like your positional data could fit in a 3-D histogram (168x24x168). This could be made considerably faster, but hopefull...

alrededor de 1 año ago | 1

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plot a smooth envelope for oscillation curves
Do you have a particular selection criteria for the peaks or formula for how you would like the smoothing performed at the ext...

alrededor de 1 año ago | 0

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How to combine Matlab's build-in functions dtw and pdist?
You'll want to take the output of DTW and put it into a form that PDIST can recognize. This should get you started: func...

alrededor de 1 año ago | 1

Filter big data simulink or matlab
<https://www.mathworks.com/help/signal/ref/hampel.html hampel> should get you started plot(hampel(OutAIS.Data)) If you n...

alrededor de 1 año ago | 1

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colthoid fitting using trajectory();
The trajectory generator uses a fast discrete solver to obtain a G2-continuous path, so some discontinuities (usu < 1 degree/met...

alrededor de 1 año ago | 0

How can i delay a signal?
You could do something simple like: s = exp(-a*(t-t0)).*sin(2*pi*(t-t0)/T); and tweak t0 to be whatever time you need th...

más de 1 año ago | 0

Power Spectrum of Colored Noises
I think you're looking for a PSD. Try |periodogram(white_noise)| or |periodogram(white_noise,[],[],Fs)|

más de 1 año ago | 0

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Why i can't plot a spectrum of a rectangular window function?
If you line up the frequency points, you'll see that your FFT is showing the zeros only. If you crank up the number of points i...

más de 1 año ago | 0

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