From moliveira@berkeley.edu Wed Mar 08 15:16:06 1995
Path: ashpoly!cascade!brgate!saturno!berkeley!moliveira
From: moliveira@berkeley.edu (Morag Oliveira)
Newsgroups: comp.dsp
Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Mar08.151606.7772@berkeley.edu>
Date: Wed, 08 Mar 1995 15:16:06 GMT
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Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems.

However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop.
This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks.

Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm.

-- 
Morag Oliveira -- UC Berkeley Department of EECS
"Tape doesn't lie at 02:14. Ears do."

From lrobertson@rwth-aachen.de Fri Mar 10 13:46:06 1995
Path: ashpoly!cascade!bigsur!rwth-aachen!lrobertson
From: lrobertson@rwth-aachen.de (Liam Robertson)
Newsgroups: comp.dsp
Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Mar10.134606.3081@rwth-aachen.de>
Date: Fri, 10 Mar 1995 13:46:06 GMT
References: <1995Mar08.151606.7772@berkeley.edu>
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In article <1995Mar08.151606.7772@berkeley.edu>, moliveira@berkeley.edu (Morag Oliveira) writes:
> Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems.
> However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop.

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

-- 
Liam Robertson | lrobertson@rwth-aachen.de
PGP Key fingerprint: D876 DFC6 24A6 F438
"Keep the channels open."

From mgirard@uu.net Sun Mar 12 07:29:06 1995
Path: ashpoly!cascade!transat!eunet-fr!teletel!uu!mgirard
From: mgirard@uu.net (Mei Girard)
Newsgroups: comp.dsp
Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Mar12.072906.6218@uu.net>
Date: Sun, 12 Mar 1995 07:29:06 GMT
References: <1995Mar08.151606.7772@berkeley.edu> <1995Mar10.134606.3081@rwth-aachen.de>
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In article <1995Mar10.134606.3081@rwth-aachen.de>, lrobertson@rwth-aachen.de (Liam Robertson) writes:
> Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in.

Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete.

-- 
Mei Girard | mgirard@uu.net
PGP Key fingerprint: B652 8163 BB3A 2CB5
"Keep the channels open."