filtering help

[marp84]

hi i need some to filtering this signal cause it's have alot of noise?

i've try to filtering with butterwoth but it's doesn't works and express filter vi also have some error?

please help me...

[Dennis_Knutson]

If you don't show the code, it's very hard to help. My guess is that you are not passing the sample rate to the filter. A DBL array has no timing information by itself and the Express VI requires a dynamic data type or waveform data type.

[marp84]

how i can pass the sample rate through filter?

[RavensFan]

Use the Build Waveform components to combine your Y array data with a dt which will be the reciprocal of your sample rate.  That creates a waveform you can feed into the Express VI.

But you actually have a larger problem.  Your Y array only has 1 element since you took a scalar value and just built it into an array.  The express VI isn't going to like that either.

You should look at the pt by pt filters under Signal Processing >> Pt by Pt >> Filters palette.

Message Edited by Ravens Fan on 07-23-2009 11:41 PM

[Dennis_Knutson]

You can't. You have no real sample rate. You are acquiring a single sample. Converting that single sample to an array does not make the array contain multiple samples. It's just an array with a single sample. I don't see a while loop so I don't understand how you even have more than a single sample in your chart. If you are using the run continous mode, stop that. 

If I recall, this problem of yours has been discussed already. You should use a function that acquires multiple samples where you specify a sample rate and not this single point at a time. Even if you put a while loop around the single point acquire with a Wait (ms) and created an actual array of samples, there would be significant jitter in your timing.