[sdiy] Digital interpolation filtering

[Tom Wiltshire]

Thanks Neil.

I had a look at this page, and tried out the raised-cosine FIR page,  
but a couple of things confused me:

Beta. What the hell is beta? I'm told to enter a value between 0 and  
1, but no clue is given as to what this is. I expect people that know  
don't need to be told, but it just made me feel ignorant.

Why does the FIR impulse have to have an odd number of taps?

Other than that, it seems to be a simple way to get a look at the  
frequency response, which is the part I understand best when I'm  
thinking about filters. The "truncate" to x bits option is dead handy  
too. As I understand more what I'm doing, I expect I might agree that  
this is a very useful page. Currently I think it's a bit over my head.

Thanks,
Tom


On 31 May 2009, at 16:28, Neil Johnson wrote:

> Tom,
>
> Please try out the page at York.  Here's the URL again:
>
>       http://www-users.cs.york.ac.uk/~fisher/mkfilter/
>
> You could start with a raised-cosine FIR filter, and you can also  
> specify truncating the filter to 16 bit data.
>
> It will give you back C code, plus graphs of responses.
>
> A very useful page.
>
> Cheers,
> Neil
> --
> http://www.njohnson.co.uk
>
>
>
>