From llindqvist@utexas.edu Wed Jul 03 23:45:40 1996
Path: ashpoly!cascade!brgate!saturno!utexas!llindqvist
From: llindqvist@utexas.edu (Lisa Lindqvist)
Newsgroups: comp.dsp
Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Jul03.234540.7478@utexas.edu>
Date: Wed, 03 Jul 1996 23:45:40 GMT
Organization: University of Texas at Austin
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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.

Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate.

-- 
Lisa Lindqvist -- University of Texas at Austin
"The hatch is open. Is anyone listening?"

From rsilva@cern.ch Fri Jul 05 19:38:40 1996
Path: ashpoly!bigsur!pacrim!krgate!eunha!cern!rsilva
From: rsilva@cern.ch (Rodrigo Silva)
Newsgroups: comp.dsp
Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Jul05.193840.8483@cern.ch>
Date: Fri, 05 Jul 1996 19:38:40 GMT
References: <1996Jul03.234540.7478@utexas.edu>
Organization: European Laboratory for Particle Physics, Geneva
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In article <1996Jul03.234540.7478@utexas.edu>, llindqvist@utexas.edu (Lisa Lindqvist) 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.

-- 
=== Rodrigo Silva ===
Dept of Electrical Engineering, European Laboratory for Particle Physics, Geneva
"5 sigma is a discovery. 7 is a question."

From lsuzuki@berkeley.edu Sun Jul 07 01:05:40 1996
Path: ashpoly!cascade!transat!ukc!fennimore!berkeley!lsuzuki
From: lsuzuki@berkeley.edu (Lars Suzuki)
Newsgroups: comp.dsp
Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Jul07.010540.5429@berkeley.edu>
Date: Sun, 07 Jul 1996 01:05:40 GMT
References: <1996Jul03.234540.7478@utexas.edu> <1996Jul05.193840.8483@cern.ch>
Organization: UC Berkeley Department of EECS
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In article <1996Jul05.193840.8483@cern.ch>, rsilva@cern.ch (Rodrigo Silva) 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.

-- 
Lars Suzuki
Opinions expressed are solely my own and not those of UC Berkeley Department of EECS.
------------------------------------------------------------

From mlopez@utexas.edu Sun Jul 07 18:17:40 1996
Path: ashpoly!bigsur!pacrim!jpgate!kamome!utexas!mlopez
From: mlopez@utexas.edu (Mathieu López)
Newsgroups: comp.dsp
Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1996Jul07.181740.1898@utexas.edu>
Date: Sun, 07 Jul 1996 18:17:40 GMT
References: <1996Jul03.234540.7478@utexas.edu> <1996Jul05.193840.8483@cern.ch> <1996Jul07.010540.5429@berkeley.edu>
Organization: University of Texas at Austin
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In article <1996Jul07.010540.5429@berkeley.edu>, lsuzuki@berkeley.edu (Lars Suzuki) writes:
> Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in.

Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.

-- 
=== Mathieu López ===
Dept of Electrical Engineering, University of Texas at Austin
"Extraordinary claims require extraordinary spectra."