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# Design filter by least squares

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#### Sandi2000

##### Junior Member level 2
The LS error methods use an error criterion that is related to the energy of
the signal or noise.
The design problem is posed by defining an error measure E as a sum (or integral) of the
squared differences between the actual and the desired frequency response over a
set of L frequency samples. This error function is defined as

Code:
E=\sum_{n = 0}^{L-1}|(H(\omega)-H(\omega)_d|^2

One of the most effective modifications of the direct LS error design methods is
to change the bands of frequencies over which the minimization is carried out.
(from the book : Digital Filter Design - Parks and Burrus).

The question : how the LS error design methods is to change the bands of frequencies ?

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The question : how the LS error design methods is to change the bands of frequencies ?
What do you want to mean ?

Sandi2000

### Sandi2000

Points: 2
What do you want to mean ?

I want to understand ,''One of the most effective modifications of the direct LS error design methods is
to change the bands of frequencies over which the minimization is carried out.''

what i understood the change bands of frequencies is done by using the iteration method, am I right?

What dou you mean by change band ?
Do you mean weighting for band ?

Sandi2000

### Sandi2000

Points: 2
What dou you mean by change band ?
Do you mean weighting for band ?
I don't know .
Digital Filter Design,Parks and Burrus ,page 70,this is a reference to the information.

I didn't check the phrase in the book. But as far as I understand, it refers to the bandwidth-changing property of a regular digital FIR filter.
Remembering that the passband freq of FIR is related to the sampling frequency with a fixed percentage, changing the sampling frequency changes the band of the filter.

Sandi2000

Points: 2