peak detection for a noisy signal offline

[bala1234]

Dear LabView experts...!

I am trying to find the peaks in my Signal offline . I like to find out the amplitude,location of the peaks and manipulate it. But the signal has noise and if i try to feed in this signal to a peak detector it gives false results as taking the small noise peaks . i like to get the large peaks (3 peaks in the given data ) .

Please help me out to detect these peaks.

When i used a peak detector.vi for a simulated noise less data its works fine. I am using LabVIEW 7.1.

Expecting your reply.

[Coq_Rouge]

Then you use any digital filter you must provide some information about the timing (sample frequency/interval). Else it will not give the correct output result.

[bala1234]

Thank you for the reply. I tried to use the digital filters in the express vi but it gives out an error that the cut off frequency shouls be less than Fs/2 . The sampling freq for my signal was 7hz.

Please give the program in LabVIEW 7.1.

[Coq_Rouge]

Sorry I can not save for Labview 7.1.

Here is a picture

[bala1234]

I attached the sample interval (in my case 0.1429sec) . But i cant see any difference in the output.

[aeastet]

Are you simply looking for the peaks? Does the time matter?

[Coq_Rouge]

Why such a slow sample frequency? A technique that I have used is to sample with a higher rate than needed and then average x samples together. As an example. Use 140 Hz as sample rate and then average every down every 20 sample to one , and present the result as 7 Hz samples.

Message Edited by Coq Rouge on 04-13-2010 02:12 PM

[aeastet · Accepted solution]

This will give you peak values without filtering. You could get the time with a little more coding.

[bala1234]

ya ..i need the time also too....! As with that peak amplitude i will calculate 10 % of the peak and where it occurs (time).So need the location of the peak.

Thank you

Bala

[aeastet]

I set the threshold to 8 and the width to 300. Got the peak values of 16.5178, 18.8016 and 23.8797.