Re: Getting started

Jerry Avins wrote: 
Gert Baars wrote:

Hello,

In order to start with DSP I want to learn how to design FIR filters.
I have read that the procedure includes an inverse Fourier transformation from H(w) to h(n) of a filter. (I seem to remember the h(n) coefficients could be found by summing of terms but forgot the details) Can I find documents about such methods without having to buy expensive books.
I already have made a moving-average FIR filter which works fine so also
my platform works fine. Now I would like to know the methods of how to transform an H(w) (frequency domain) response of LPF,BPF and LPF to the coefficients (h0,h1....hn).

Please let me know if you know how to obtain this information.


FIR filters are usually designed using a computer program to generate the coefficients using an empirical approximation rule. Some programs to do that are available as free downloads.

I applaud learning do do the job by hand, just as I believe that everyone should be able to add a column of numbers. Nevertheless, a program will usually design a better practical filter than you or I.

See http://iowegian.com/

Jerry


Thank you for the link. I downloaded scopeFIR and that seems to
be the easiest way. But what if the filter (roll-off frequency) has to be variable?
How are the coefficients implemented? Lets say we have a filter with
3 taps. Does that mean the first tap is before the first delay and the last after the last delay and the number of delays = 2?
.

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