From asantos@hanse.de Tue Nov 01 06:25:01 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!hanse!asantos
From: asantos@hanse.de (Andrei Santos)
Newsgroups: comp.dsp
Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994Nov01.062501.7391@hanse.de>
Date: Tue, 01 Nov 1994 06:25:01 GMT
Organization: Hanse-Netzwerk Hamburg
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Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead.
By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample.

Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip?

-- 
Andrei Santos
Tape trading list upon request. SASE required for international mail.

From jkuznetsov@kiae.su Wed Nov 02 09:22:01 1994
Path: ashpoly!cascade!mxgate!coyoacan!kiae!jkuznetsov
From: jkuznetsov@kiae.su (Julien Kuznetsov)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994Nov02.092201.5387@kiae.su>
Date: Wed, 02 Nov 1994 09:22:01 GMT
References: <1994Nov01.062501.7391@hanse.de>
Organization: Kurchatov Institute of Atomic Energy, Moscow
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In article <1994Nov01.062501.7391@hanse.de>, asantos@hanse.de (Andrei Santos) writes:
> Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.
> The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead.

Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in.

-- 
Julien Kuznetsov
Opinions expressed are solely my own and not those of Kurchatov Institute of Atomic Energy, Moscow.
------------------------------------------------------------

From mwatanabe@cern.ch Thu Nov 03 14:16:01 1994
Path: ashpoly!cascade!transat!sunet!nordrelay!cern!mwatanabe
From: mwatanabe@cern.ch (Morag Watanabe)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994Nov03.141601.5270@cern.ch>
Date: Thu, 03 Nov 1994 14:16:01 GMT
References: <1994Nov01.062501.7391@hanse.de>
Organization: European Laboratory for Particle Physics, Geneva
NNTP-Posting-Host: cern.ch
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In article <1994Nov01.062501.7391@hanse.de>, asantos@hanse.de (Andrei Santos) writes:
> Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in.

-- 
Morag Watanabe | mwatanabe@cern.ch
PGP Key fingerprint: 7755 2B05 F61C C6A8
"Keep the channels open."