"Frequency notch filtering, is it possible?"

Question

Hello all,

I've been trying to find a way (after a Fourier transform) to filter out all but a very narrow band of frequencies so I can concentrate on these in the classification process I have. Is there any way I could perform a logical AND on all members of a value series to eliminate all but the ones I want?

I've been trying to use FilterTransformation but I can't quite get the sharpness and I also can't think of a way to use SingleCombinedFunction (but I have been staring at it for too long perhaps).

Thanks in advance for any advice

best regards

Andrew

Andrew2 · Answer

I figured out a way - it's attached. I'm guessing that there might be better ways. Thanks for spending time on this. Andrew

Andrew2 · Answer

Hello Sebastian, Thanks - I get it now - I was trying to do too much with the value series operators I think. I've attached a cut down version of the process. In this example, I want to suppress all frequencies outside the range 175 to 225. I can't quite (yet ;) ) work out how to set the attribute FFT(sinus)_dim_1 to 0 when the frequency attribute in the same example is less than 175 or greater than 225. I'm guessing there's a neat way to do it but as usual I've been staring at it for too long. Any advice would be appreciated. best regards, Andrew

land · Answer

Hi Andrew,
you could filter out the according attribute using an AttributeFilter after the series processing, when everything is stored in an exampleSet again.
If this doesn't work, please post your process below, so that I can see, what you are actually doing.

Greetings,
  Sebastian