From mkang@delphi.com Mon Feb 26 02:47:57 1996
Path: ashpoly!bigsur!pacrim!krgate!eunha!delphi!mkang
From: mkang@delphi.com (Mathieu Kang)
Newsgroups: comp.dsp
Subject: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Feb26.024757.1480@delphi.com>
Date: Mon, 26 Feb 1996 02:47:57 GMT
Organization: Delphi Internet Services
NNTP-Posting-Host: delphi.com
X-Newsreader: TIN [version 1.2 PL2]
Lines: 11

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?

-- 
Mathieu Kang | mkang@delphi.com
PGP Key fingerprint: FC81 641E 982B 25EF
"Keep the channels open."

From sgarcia@kiae.su Tue Feb 27 18:20:57 1996
Path: ashpoly!cascade!mxgate!coyoacan!kiae!sgarcia
From: sgarcia@kiae.su (Sergei García)
Newsgroups: comp.dsp
Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Feb27.182057.5035@kiae.su>
Date: Tue, 27 Feb 1996 18:20:57 GMT
References: <1996Feb26.024757.1480@delphi.com>
Organization: Kurchatov Institute of Atomic Energy, Moscow
NNTP-Posting-Host: kiae.su
X-Newsreader: NewsWatcher 2.0b24
Lines: 11

In article <1996Feb26.024757.1480@delphi.com>, mkang@delphi.com (Mathieu Kang) 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.

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

-- 
Sergei García | sgarcia@kiae.su
PGP Key fingerprint: 8E05 7840 746D 338A
"Keep the channels open."