Exponenital Filter design

Hello Folks

At the moment I am trying to design a one pole simple IIR digital 
filter to simulate exponential delay effect with simple equations 
like 1 - e^(-t/T), where T is a known time constant. I think an one 
pole IIR filter will do it: Y[n] = alpha/[1-(1-alpha)Z^(-1)] can 
simulate the delay effect when alpha < 1. But I am quite pullzing 
how the alpha will be determined. i'd appreciate if you shed some 
light on this.

Best regards,

Gordon Ao
	

Dear Gordon,

Go to my website http://www.sevenwoodsaudio.com/ and look for 
Consulting and articles, and find article AN-11. It should be helpful 
to you.

Chris Moore

On Mon, 24 Jan 2005 08:41:45 -0000, gordon_ao wrote:
	Hello Folks

At the moment I am trying to design a one pole simple IIR digital
filter to simulate exponential delay effect with simple equations
like 1 - e^(-t/T), where T is a known time constant. I think an one
pole IIR filter will do it: Y[n] = alpha/[1-(1-alpha)Z^(-1)] can
simulate the delay effect when alpha < 1. But I am quite pullzing
how the alpha will be determined. i'd appreciate if you shed some
light on this.

Best regards,

Gordon Ao
	-----------------------------------
Seven Woods Audio, Inc.                Christopher Moore
Concepts, Products, Circuits for Audio    Analog/Digital
moore@moor...
http://www.SevenWoodsAudio.com