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Filtering Analog Input Data

Hello again,
I need help in the "Filter" area. Let me start by saying I'm not the most experienced in filters, so any help in this area would be very helpful. My code has taken me quite a while to develop (just because I'm not able to use LV daily). My code basically acquires multiple channels of acoustic data, however I really need to filter analog input data prior to doing any scaling, amplification, etc. My nyquist frequency is 51.2Khz. My frequency of interest is 10-20kHz. So here's my question. I know I need a Filter. My options are either electronically filter (low pass and high pass, which would require to purchase expensive instrumentation) or write code to Filter analog input data prior to scaling, amplification. Writing Code to filter analog input data just as good as electronically filtering? Can anyone help in this area, any replys are welcome?
 
Scott
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Message 1 of 3
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Alv <x@no.email> wrote in news:1142604672875-339715@exchange.ni.com:

> Hello again,
> I need help in the "Filter" area. Let me start by saying I'm not
> the most experienced in filters, so any help in this area would be
> very helpful. My code has taken me quite a while to develop (just
> because I'm not able to use LV daily). My code
> basically acquires multiple channels of acoustic data,
> however I really need to filter analog input data prior to doing
> any scaling, amplification, etc. My nyquist frequency is 51.2Khz.
> My frequency of interest is 10-20kHz. So here's my question. I know I
> need a Filter. My options are either electronically filter (low
> pass and high pass, which would require to purchase expensive
> instrumentation) or write code to Filter analog input
> data prior to scaling, amplification. Writing Code to filter
> analog input data just as good as electronically filtering? Can anyone
> help in this area, any replys are welcome?
> Scott
>

If the data you are acquiring exceeds your Nyquist frequency (which is half
your sample rate), software filtering is not an option. If you are sure
that the contribution of frequencies outside the Nyquist range are
extremely small, software filtering will be just as good in many ways, and
better in other ways, than hardware filtering.

--
Scott
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Thanks for your help. My transducer usable frequency range is slightly above my frequency of interest (10-20kHz OTO, one third octave), therefore I'd need to filter unwanted frequencies such as 0-8Hz and ~23khz and above.
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