FIltering Noise

[marp84]

i've signal so lot with noise and it's disturb my real signal, how i can remove this noise and i see it's 50hz or 60hz from my signal?

for DAQ i use 1208FS.

tanx

[Eugen Graf]

Use butterworth lowpass filter, it's very easy to use and filters very good

[marp84]

i've try to make it but it's still have a noise?

[ESST]

Hi,

Could you post some information about the filtering you have tried, and the signal you are interested in? Maby a vi, and a plot?

[marp84]

here's the vi

u3.vi

[ESST]

As far as I can see, that cannot work. When you use the non PtByPt filters, you need to give it an array containing the waveform to filter, not an array containing a single value. I would recommend looking at the following examples:

PtByPt and Array Based Filter.vi

Extract the sine Wave.vi

This should show you how to do basic filtering of your signal.

You should be able to find them under menu "Help/Find Examples", then searching for "Butterworth".

[ASTDan]

As a general rule, if you can, you want to try and filter or reduce the noise before you acquire it.

Here is a great white paper on the topic.

http://zone.ni.com/devzone/cda/tut/p/id/3344

Dan

[Matthew Zaleski]

In general you need to know what is your frequency range of interest. If the data contains usable frequency content from 0 to 3 Hz, then applying a 5 or 6 Hz lowpass filter should help. But sometimes your frequency of interest is not near 0 Hz. In those cases, look at passband or highpass filters.

Your initial post seems to indicate you may need a notch filter (60 Hz noise from electrical?).