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Thread Subject:
pre-emphasis filter

Subject: pre-emphasis filter

From: Regina

Date: 12 Mar, 2009 03:49:01

Message: 1 of 3

hi!

does anyone know how to do a pre-emphasis filter
it will be used for a vector (1xN double array) containing values computed from a bounding box aspect ratio.

the formula for the pre-emphasis filter is this:

H(z) = 1-az^-1

with a chosen empirically to be = 1.0

i hope someone can help me code this.

thanks!

Subject: pre-emphasis filter

From: shilan

Date: 17 Apr, 2009 18:29:03

Message: 2 of 3

i know this one should b used:
s(n)-(alpha)s(n-1)
using alpha =3D 0.95

but still don't know how

On Mar 12, 6:49=A0am, "Regina " <velasquezreg...@rocketmail.com> wrote:
> hi!
>
> does anyone know how to do a pre-emphasis filter
> it will be used for a vector (1xN double array) containing values compute=
d from a bounding box aspect ratio.
>
> the formula for the pre-emphasis filter is this:
>
> H(z) =3D 1-az^-1
>
> with a chosen empirically to be =3D 1.0
>
> i hope someone can help me code this.
>
> thanks!

Subject: pre-emphasis filter

From: Wayne King

Date: 17 Apr, 2009 20:32:03

Message: 3 of 3

Hi Regina, if you want to have an FIR pre-emphasis (boost high frequncies) filter, you can filter your input as:

y=filter([1 -0.90],1,x);

where x is the input vector.
To see that this is a high pass filter, you can run:

fvtool([1 -0.90],1)

of course I just picked a value for the coefficient on z^{-1} close to 1. You can play with that a little to get the filter you want.

hope that helps,
wayne

"Regina " <velasquezregina@rocketmail.com> wrote in message <gpa0nd$b0q$1@fred.mathworks.com>...
> hi!
>
> does anyone know how to do a pre-emphasis filter
> it will be used for a vector (1xN double array) containing values computed from a bounding box aspect ratio.
>
> the formula for the pre-emphasis filter is this:
>
> H(z) = 1-az^-1
>
> with a chosen empirically to be = 1.0
>
> i hope someone can help me code this.
>
> thanks!

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