From bcampbell@pipeline.com Sat Nov 04 05:20:33 1995
Path: ashpoly!cascade!transat!eunet-de!hansebox!pipeline!bcampbell
From: bcampbell@pipeline.com (Bastien Campbell)
Newsgroups: comp.dsp
Subject: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Nov04.052033.4873@pipeline.com>
Date: Sat, 04 Nov 1995 05:20:33 GMT
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Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample.
This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks.

Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm.

-- 
Bastien Campbell
Opinions expressed are solely my own and not those of The Pipeline Internet Network.
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From dmartinez@demon.co.uk Sat Nov 04 09:37:33 1995
Path: ashpoly!cascade!bigsur!demon!dmartinez
From: dmartinez@demon.co.uk (Dmitri Martínez)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Nov04.093733.7672@demon.co.uk>
Date: Sat, 04 Nov 1995 09:37:33 GMT
References: <1995Nov04.052033.4873@pipeline.com>
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In article <1995Nov04.052033.4873@pipeline.com>, bcampbell@pipeline.com (Bastien Campbell) writes:
> Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

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

-- 
Dmitri Martínez | dmartinez@demon.co.uk
PGP Key fingerprint: 4DFF 6F89 EB8B BDF3
"Keep the channels open."

From eschneider@berkeley.edu Mon Nov 06 00:13:33 1995
Path: ashpoly!cascade!mxgate!coyoacan!berkeley!eschneider
From: eschneider@berkeley.edu (Elaine Schneider)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Nov06.001333.1011@berkeley.edu>
Date: Mon, 06 Nov 1995 00:13:33 GMT
References: <1995Nov04.052033.4873@pipeline.com>
Organization: UC Berkeley Department of EECS
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In article <1995Nov04.052033.4873@pipeline.com>, bcampbell@pipeline.com (Bastien Campbell) 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.

-- 
Elaine Schneider
Opinions expressed are solely my own and not those of UC Berkeley Department of EECS.
------------------------------------------------------------

From skim@unam.mx Mon Nov 06 15:56:33 1995
Path: ashpoly!cascade!mxgate!coyoacan!unam!skim
From: skim@unam.mx (Sergei Kim)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Nov06.155633.4358@unam.mx>
Date: Mon, 06 Nov 1995 15:56:33 GMT
References: <1995Nov04.052033.4873@pipeline.com>
Organization: Universidad Nacional Autónoma de México (DGSCA)
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In article <1995Nov04.052033.4873@pipeline.com>, bcampbell@pipeline.com (Bastien Campbell) 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.

-- 
=== Sergei Kim ===
Dept of Electrical Engineering, Universidad Nacional Autónoma de México (DGSCA)
"We don't sign stars. We build them."