For an introduction to DSP and filtering, it's hard to beat Steven 
Smith's book
http://www.dspguide.com/

You can read it for free, which makes it even better.

Jack


Andre Abelian wrote:
> Hi to all,
>
> I am using external 13 bit ADC witch originally won't necessary
> to go that high resolution "not under my control" now the result
> I am getting is noisy numbers are going high and low. what I did is
> reading it 10 times then I add them together then divide it by 10.
> It helps but one of our engineer asked me to add software low pass
> filter witch I am familiar with it. Reading 10 times values are up to 15 point
> different. 
> My question is do you have any experience or know how software LPF work?
> any link or info will appreciate. I searched piclist.com not enough info
> I found to understand what to do.
>
> thank you for your help
>
> Andre 
>
>   
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