From esilva@unam.mx Thu May 12 16:14:34 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!unam!esilva
From: esilva@unam.mx (Emi Silva)
Newsgroups: comp.dsp
Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994May12.161434.4775@unam.mx>
Date: Thu, 12 May 1994 16:14:34 GMT
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Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop.
The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead.

Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate.

-- 
Emi Silva -- Universidad Nacional Autónoma de México (DGSCA)
"Do not worship the copy."

From yrobertson@berkeley.edu Sat May 14 08:26:34 1994
Path: ashpoly!cascade!brgate!saturno!berkeley!yrobertson
From: yrobertson@berkeley.edu (Yuki Robertson)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994May14.082634.8370@berkeley.edu>
Date: Sat, 14 May 1994 08:26:34 GMT
References: <1994May12.161434.4775@unam.mx>
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In article <1994May12.161434.4775@unam.mx>, esilva@unam.mx (Emi Silva) writes:
> Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.
> However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop.

Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.

-- 
Yuki Robertson -- UC Berkeley Department of EECS
"Row 14. No joke."

From dchoi@hanse.de Sat May 14 16:15:34 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!hanse!dchoi
From: dchoi@hanse.de (Dave Choi)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994May14.161534.3709@hanse.de>
Date: Sat, 14 May 1994 16:15:34 GMT
References: <1994May12.161434.4775@unam.mx> <1994May14.082634.8370@berkeley.edu>
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In article <1994May14.082634.8370@berkeley.edu>, yrobertson@berkeley.edu (Yuki Robertson) writes:
> Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.

Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.

-- 
Dave Choi | dchoi@hanse.de
PGP Key fingerprint: 12A8 8318 BA40 B8FA
"Keep the channels open."

From schoi@netcom.com Sun May 15 01:23:34 1994
Path: ashpoly!cascade!transat!sunet!nordrelay!netcom!schoi
From: schoi@netcom.com (Seo-yeon Choi)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994May15.012334.7348@netcom.com>
Date: Sun, 15 May 1994 01:23:34 GMT
References: <1994May12.161434.4775@unam.mx> <1994May14.082634.8370@berkeley.edu>
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In article <1994May14.082634.8370@berkeley.edu>, yrobertson@berkeley.edu (Yuki Robertson) writes:
> Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.

Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.

My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise!

-- 
Seo-yeon Choi
Tape trading list upon request. SASE required for international mail.