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# Greg Dionne

### MathWorks

146 total contributions since 2012

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How to edit original data in for-each equivalent statement
You can often avoid the need for references and the for-loop altogether in MATLAB. This example should get you started: classd...

alrededor de 2 meses ago | 0

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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

6 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...

6 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...

6 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/...

7 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...

7 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...

7 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...

7 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...

8 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...

8 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...

8 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...

8 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...

8 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...

9 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...

10 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...

10 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...

alrededor de 1 año 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....

alrededor de 1 año 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...

alrededor de 1 año ago | 0

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

alrededor de 1 año 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...

alrededor de 1 año 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...

más 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...

más 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...

más 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...

más 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...

más 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...

más 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...

casi 2 años ago | 0

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

casi 2 años ago | 0

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