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# Greg Dionne

### MathWorks

146 total contributions since 2012

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Answered
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...

4 mesi ago | 0

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

8 mesi ago | 0

Answered
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...

8 mesi ago | 0

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Answered
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...

9 mesi ago | 2

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Answered
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/...

9 mesi ago | 1

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Answered
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...

9 mesi ago | 0

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Answered
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...

9 mesi ago | 0

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Answered
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...

10 mesi ago | 1

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Answered
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...

10 mesi ago | 0

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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...

10 mesi ago | 0

Answered
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...

10 mesi ago | 1

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Answered
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...

10 mesi ago | 0

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Answered
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...

10 mesi ago | 1

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Answered
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...

12 mesi ago | 0

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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...

12 mesi ago | 0

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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...

12 mesi ago | 0

Answered
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...

oltre un anno ago | 0

Answered
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....

oltre un anno ago | 0

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Answered
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...

oltre un anno ago | 0

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Answered
How can I determine the diameter (inner and outer) of the ring profile?
Try this link: <https://www.mathworks.com/help/images/detect-and-measure-circular-objects-in-an-image.html>

oltre un anno ago | 0

Answered
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...

oltre un anno ago | 1

Answered
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...

oltre un anno ago | 0

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Answered
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...

oltre un anno ago | 1

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Answered
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...

oltre un anno ago | 0

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Answered
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...

oltre un anno ago | 1

Answered
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...

oltre un anno ago | 1

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Answered
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...

oltre un anno ago | 0

Answered
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...

circa 2 anni ago | 0

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

circa 2 anni ago | 0

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Answered
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...

circa 2 anni ago | 0

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