From vdubois@illinois.edu Mon Apr 17 03:13:58 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!illinois!vdubois
From: vdubois@illinois.edu (Valeria Dubois)
Newsgroups: comp.dsp
Subject: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr17.031358.9912@illinois.edu>
Date: Mon, 17 Apr 1995 03:13:58 GMT
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Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier.

This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks.
However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop.

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

-- 
Valeria Dubois <vdubois@illinois.edu>
*PLONK* filter active for trolls.
Commodore Amiga 500 (1MB OCS) - NetBSD 1.0

From vtanaka@hanse.de Tue Apr 18 06:16:58 1995
Path: ashpoly!cascade!transat!ukc!fennimore!hanse!vtanaka
From: vtanaka@hanse.de (Valeria Tanaka)
Newsgroups: comp.dsp
Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr18.061658.5513@hanse.de>
Date: Tue, 18 Apr 1995 06:16:58 GMT
References: <1995Apr17.031358.9912@illinois.edu>
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In article <1995Apr17.031358.9912@illinois.edu>, vdubois@illinois.edu (Valeria Dubois) writes:
> Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier.

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

-- 
Valeria Tanaka | vtanaka@hanse.de
PGP Key fingerprint: 9264 A6BC 71FB 6DBF
"Keep the channels open."

From hsantos@rwth-aachen.de Wed Apr 19 17:42:58 1995
Path: ashpoly!cascade!transat!ukc!fennimore!rwth-aachen!hsantos
From: hsantos@rwth-aachen.de (Hana Santos)
Newsgroups: comp.dsp
Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr19.174258.2484@rwth-aachen.de>
Date: Wed, 19 Apr 1995 17:42:58 GMT
References: <1995Apr17.031358.9912@illinois.edu>
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In article <1995Apr17.031358.9912@illinois.edu>, vdubois@illinois.edu (Valeria Dubois) writes:
> Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier.
> This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks.

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

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

-- 
Hana Santos | hsantos@rwth-aachen.de
PGP Key fingerprint: 3DFD 2406 6710 0902
"Keep the channels open."