From aeriksson@hanse.de Sun Apr 09 19:47:01 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!hanse!aeriksson
From: aeriksson@hanse.de (Aiko Eriksson)
Newsgroups: comp.dsp
Subject: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr09.194701.8785@hanse.de>
Date: Sun, 09 Apr 1995 19:47:01 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?

-- 
Aiko Eriksson
Tape trading list upon request. SASE required for international mail.

From blaurent@panix.com Mon Apr 10 08:15:01 1995
Path: ashpoly!bigsur!pacrim!jpgate!kamome!panix!blaurent
From: blaurent@panix.com (Brian Laurent)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr10.081501.2798@panix.com>
Date: Mon, 10 Apr 1995 08:15:01 GMT
References: <1995Apr09.194701.8785@hanse.de>
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In article <1995Apr09.194701.8785@hanse.de>, aeriksson@hanse.de (Aiko Eriksson) 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.

-- 
Brian Laurent -- Public Access Unix of New York
"Row 14. No joke."

From achoi@purdue.edu Tue Apr 11 09:33:01 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!purdue!achoi
From: achoi@purdue.edu (Anja Choi)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr11.093301.6645@purdue.edu>
Date: Tue, 11 Apr 1995 09:33:01 GMT
References: <1995Apr09.194701.8785@hanse.de> <1995Apr10.081501.2798@panix.com>
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In article <1995Apr10.081501.2798@panix.com>, blaurent@panix.com (Brian Laurent) writes:
> Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.

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

-- 
Anja Choi | achoi@purdue.edu
PGP Key fingerprint: B497 A5C6 0E52 6AE2
"Keep the channels open."