From ggarcia@clari.net Fri Mar 17 18:25:32 1995
Path: ashpoly!cascade!transat!eunet-de!hansebox!clari!ggarcia
From: ggarcia@clari.net (Graham García)
Newsgroups: comp.dsp
Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Mar17.182532.3933@clari.net>
Date: Fri, 17 Mar 1995 18:25:32 GMT
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Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip.

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?

-- 
Graham García -- ClariNet Communications Corp
"A soul is not exclusive to biology."

From lweber@berkeley.edu Sat Mar 18 23:31:32 1995
Path: ashpoly!bigsur!pacrim!jpgate!kamome!berkeley!lweber
From: lweber@berkeley.edu (Lisa Weber)
Newsgroups: comp.dsp
Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Mar18.233132.5058@berkeley.edu>
Date: Sat, 18 Mar 1995 23:31:32 GMT
References: <1995Mar17.182532.3933@clari.net>
Organization: UC Berkeley Department of EECS
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In article <1995Mar17.182532.3933@clari.net>, ggarcia@clari.net (Graham García) 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.

-- 
=== Lisa Weber ===
Dept of Electrical Engineering, UC Berkeley Department of EECS
"Hold for relay."