Find duration of signal
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I have a set of signals that due to some unknown error have been acquired with millions of empty datapoints. Is there a way I can automatically detect the moment the signal ends so I can delete everything from that point onwards?
Thanks everyone.
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Star Strider
2020년 9월 9일
There are no actual ‘missing’ values, just a very low amplitude signal after about element 40:
T1 = readtable('sampledata.csv');
figure
semilogy(abs(T1{:,1}))
grid
producing:
That would appear to be legitimate data.
.
Xavier
2020년 9월 10일
This depends on how you define legitimate data, if you unplug a probe/sensor from an oscilloscope it will continue to display numbers and a waveform. If you're trying to measure a signal then it is fair to call recorded noise invalid data
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Xavier
2020년 9월 10일
Something like this may work for you
Raw data:
data = readmatrix('sampledata.csv');
avgdat = movmean(abs(data), 5);
threshold = 0.01;
data(avgdat < threshold) = [];
plot(data)
추가 답변 (1개)
Steven Lord
2020년 9월 9일
If the empty data points are represented by NaN then find the 'last' 1 element of the vector that isfinite.
x = [1:10 NaN(1, 5)]
find(isfinite(x), 1, 'last')
If the vector has no missing data inside it, you could instead just rmmissing.
rmmissing(x)
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