From bfournier@pacbell.net Tue May 24 19:12:12 1994
Path: ashpoly!cascade!brgate!saturno!pacbell!bfournier
From: bfournier@pacbell.net (Bruno Fournier)
Newsgroups: comp.dsp
Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994May24.191212.3088@pacbell.net>
Date: Tue, 24 May 1994 19:12:12 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.

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

-- 
=== Bruno Fournier ===
Dept of Electrical Engineering, Pacific Bell Internet Services
"A soul is not exclusive to biology."

From tnovak@cam.ac.uk Wed May 25 08:26:12 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!cam!tnovak
From: tnovak@cam.ac.uk (Tobias Novak)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1994May25.082612.9222@cam.ac.uk>
Date: Wed, 25 May 1994 08:26:12 GMT
References: <1994May24.191212.3088@pacbell.net>
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In article <1994May24.191212.3088@pacbell.net>, bfournier@pacbell.net (Bruno Fournier) 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.

Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns.

-- 
Tobias Novak | tnovak@cam.ac.uk
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