[PD] FIR filter design

MLN Kazem, Aerospace Engineering M.Kazem at bristol.ac.uk
Tue Aug 27 15:47:15 CEST 2002


did you sort the equation out? - I have just read your email and am 
confused about your equation - do you mean 
y[n] = ax[n] + bx[n-1] + cx[n-2] + .... 
x[n] being the digital input to the FIR (x[n-1] being the input 
delayed by 1 time sample) and a,b,c being the coefficients of the 
impulse response of the filter that you require, the number of 
coefficients therefore dictating the final x[n-?] delay that is 
required to implement the FIR - ie convolution of input and FIR?
I presume to dictate cut-off freq of the FIR you are going to have to 
work in the freq domain as opposed to the time domain - or at least for
the calculation- or am I getting very confused here??
just interested


On Sat, 24 Aug 2002 01:04:00 +0100 João_M_Pais <jmmmpl at netcabo.pt>

> Dear list,
> I am writing a patch for FIR filter design in the old way, by realizing the
> formula y(n)=a(n)+b(n-1)+c(n-2)+...+?(n-??) with z~. All the work is ready,
> but I am just missing the designs. I wanted to make also some presets and
> the ability to design the filter from normal parameters (type, cutoff freq,
> etc). Does anybody knows how to make the calculus for FIR filters, to know
> the equation?
> By the way, there is a bug in the dynamic instructions: when the instruction
> "vis 0" is given to a already closed subpatch, the program crashes.
> Thanks as usual,
> Joco Miguel Pais
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MLN Kazem, Aerospace Engineering
M.Kazem at bristol.ac.uk
Tel. 0117 9288219
Fax. 0117 9272771

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