Digital Filter Design Software

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2 total messages Started by Andy Adams Tue, 26 Mar 1991 21:06

#1624

Author: Andy Adams
Date: Tue, 26 Mar 1991 21:06

38 lines
2074 bytes

        I'm currently involved in FIR digital filter design.
        I've been using the CARL digital filter design software
        by Mcclellan and Parks designed some 10 years ago. 

        I am trying to design fairly large (16->32 tap) FIR
        filters for image sharpness correction/enhancement. Ideally,
        I would like to be able to specify filter gains at various
        frequencies and have the program optimally design the coeffs.
        The band-edge, band-gain, band-ripple approach of CARL
        seems to be very awkward and unpredictable for this 
        type of filter design. 

        I'm also designing very large (256->1024) tap interpolation
        filters. CARL is limited to 128 coeffs.

        If anybody knows of any more recent offerings or newer
        algorithms for filter design/analysis software, please 
        post or e-mail some recommendations.

        I've seen some references to Gabriel from UC Berkley.
        Is this any good? How do I obtain it? Does it run on a Sun?
        Can I ftp something??

        I realize this has probably been asked in the past, but
        I haven't captured the info.

        I would prefer that to run on Sun workstation (Sun3 or Sparc).

                Thanks much,
        
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Andy Adams, KEPS Inc.           |internet: ada@epps.kodak.com
an Eastman Kodak Company        |
164 Lexington Rd.               |
Billerica, Ma. 01821            |
(508)670-6593                   |
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Re: Digital Filter Design Software

#1628

Author: Norbert Hanke
Date: Thu, 28 Mar 1991 11:43

22 lines
1467 bytes

In article <2345@gonzales.munsell.UUCP> ada@munsell.UUCP (Andy Adams) writes:
>
>        I am trying to design fairly large (16->32 tap) FIR
>        filters for image sharpness correction/enhancement. Ideally,
>        I would like to be able to specify filter gains at various
>        frequencies and have the program optimally design the coeffs.
>        The band-edge, band-gain, band-ripple approach of CARL
>        seems to be very awkward and unpredictable for this 
>        type of filter design. 

Try to use them Remez Exchange Algorithm, if you want to design linear
phase filters.

Internally, Remez builds a large grid of the specified frequencies, each
point having its desired value and the weight. It should be possible to
adapt Remez in a way to allow for arbitrary frequency responses, not just
the band-edge, band-gain, band-weight approach.

Norbert Hanke
Power Electronics &
Electrometrology
ETH Zurich, Switzerland

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