hi i need to design a notch filter for eliminating ECG hum..i am working with NI ELVIS work station...and LABVIE 8.0

[Joaana]

hi i need to design a notch filter for eliminating ECG hum..i am working with NI ELVIS work station...and LABVIEW 8.0. Unfortunately it needs an addon software "Digital filter design toolkit", which i dont have. Its urgent..can some 1 plzz help me out.

[CharlieM]

Hi and Happy Halloween,

Depending on the license you have for LabVIEW and the toolsets you have installed, you may be able to have a "notch" filter. I would search your pallet for "Bandstop" because a notch is a type of Bandstop filter. Or, you can make a notch out of a high-pass and a low-pass or you can use the filter express VI. If these VIs are not on your pallet than you probably only have the LabVIEW Base and thus, cannot use these options.

[marp84]

i've labview 8.0 professional development system can i bulid the notch filter in this software and if it's can how to build it ?

do you know what is the lower and higer cut-off frequency  of this filter?

tanx before

[ga101]

One way to do this can be to go to functions pallette on the block diagram then Express VIs then signal analysis then filter. Select Band stop filter and put same frequency as lower as well as higher cutoff. It should work.

[marp84]

is the notch filter same with bandstop filter?

can tell me more details about how to design the notch filter and how to setting the cut-off frequency ?

tanx 

[johnsold]

A notch filter is not quite the same as a bandstop filter, although they have many similarities.  A notch filter behaves like a resonant circuit in that it has center frequency and width parameters.  The bandstop filter is essentially a low pass filter cascaded with a high pass filter.  It will have low frequency and high frequency cutoff parameters.

To eliminate a single frequency, the notch filter is best.  To remove a range of frequencies the bandstop filter is more versatile.

Lynn 

[marp84]

If the notch filter is best so can you tell me more details about how to design it (not bandstop filter) in labview  ?

and can you give some project that use notch filter ?

tanx 

Message Edited by marp84 on 10-21-2008 05:26 PM

[johnsold]

I do not have time to look into this in detail now.  A quick glance at the Filters palette did not show any notch filters.  Perhaps you can get sufficient performance from the FIR Narrowband Coefficients.vi and the FIR Narrowband Filter.vi.  Look at the detailed help pages fro information on applying them.

I think I would try these before trying to take a notch filter from a filter handbook and implementing in LV.  These filter VIs have had  quite a bit of optimization and probably would work better than a "do it yourself" notch filter.

You might also look at elliptic fitlers.

Lynn