MATLAB: Detecting rise time from noisy data

noisy datarise time detectionSignal Processing Toolbox

I have a noisy set of pressure vs time data. The pressure starts near vacuum level and begins to rise at a certain time which I want to determine. This can be done just by eyeballing to a fairly good accuracy but wanted to know if there is a statistical method to do so. The data I am looking at is in the attached excel sheet. Thanks

Best Answer

Try running a median filter on it, medfilt1(). It will get rid of the spurious spike but keep the monotonic increases. Make the filter window about twice the width of the spike.

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MATLAB: Rise time fs meaning

A wild guess: femtoseconds?

MATLAB: Rise/fall time

%set-up parameters
fs=44100; %CD quality - also conveniently divisible by 30 and 25
stim_dur=.025; %duration in seconds
ISI_dur=.030; %ISI duration in seconds
ramp_dur=.010; %ramp duration in seconds
t=0:1/fs:stim_dur-1/fs;
f1=500;
f2=1000;
%create signals
xt1=sin(2*pi*f1*t);
xt2=sin(2*pi*f2*t);
%setup ramp
rampSamps = floor(fs*ramp_dur);
window=hanning(2*rampSamps)'; %hanning window is cosine^2 this will change depending on the kind of ramp you want
w1=window(1:ceil((length(window))/2)); %use the first half of hanning function for onramp
w2=window(ceil((length(window))/2)+1:end); %use second half of hanning function of off ramp
w1 = [w1 ones(1,length(xt1)-length(w1))];
w2 = [ones(1,length(xt1)-length(w2)) w2];
%ramp stimuli
xt1_ramped = xt1.*w1.*w2; 
xt2_ramped = xt2.*w1.*w2; 
%generate ISI
ISI=zeros(ISI_dur*fs,1);
%final stimulus
out=[xt1_ramped';ISI;xt2_ramped'];
plot(out)

Best Answer

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MATLAB: Rise time fs meaning

MATLAB: Rise/fall time

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