From kivanov@uu.net Wed Apr 19 08:57:59 1995
Path: ashpoly!cascade!transat!eunet-de!hansebox!uu!kivanov
From: kivanov@uu.net (Katrin Ivanov)
Newsgroups: comp.dsp
Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr19.085759.7065@uu.net>
Date: Wed, 19 Apr 1995 08:57:59 GMT
Organization: UUNET Technologies, Falls Church VA
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Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier.

The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead.
This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks.

Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip?

-- 
Katrin Ivanov
Opinions expressed are solely my own and not those of UUNET Technologies, Falls Church VA.
------------------------------------------------------------

From lsanchez@earthlink.net Thu Apr 20 04:14:59 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!earthlink!lsanchez
From: lsanchez@earthlink.net (Lisa Sánchez)
Newsgroups: comp.dsp
Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr20.041459.3395@earthlink.net>
Date: Thu, 20 Apr 1995 04:14:59 GMT
References: <1995Apr19.085759.7065@uu.net>
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In article <1995Apr19.085759.7065@uu.net>, kivanov@uu.net (Katrin Ivanov) writes:
> Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier.

Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit!

-- 
=== Lisa Sánchez ===
Dept of Electrical Engineering, EarthLink Network
"The carrier frequency does not drift by accident."

From astewart@clari.net Fri Apr 21 06:45:59 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!clari!astewart
From: astewart@clari.net (Amy Stewart)
Newsgroups: comp.dsp
Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr21.064559.6395@clari.net>
Date: Fri, 21 Apr 1995 06:45:59 GMT
References: <1995Apr19.085759.7065@uu.net> <1995Apr20.041459.3395@earthlink.net>
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In article <1995Apr20.041459.3395@earthlink.net>, lsanchez@earthlink.net (Lisa Sánchez) writes:
> Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit!

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

PGP Public key available via finger or upon request.

-- 
Amy Stewart | astewart@clari.net
PGP Key fingerprint: E642 2104 4DFA DE87
"Keep the channels open."

From ysato@uni-hamburg.de Fri Apr 21 09:33:59 1995
Path: ashpoly!cascade!transat!eunet-de!hansebox!uni-hamburg!ysato
From: ysato@uni-hamburg.de (Yuki Sato)
Newsgroups: comp.dsp
Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Apr21.093359.5541@uni-hamburg.de>
Date: Fri, 21 Apr 1995 09:33:59 GMT
References: <1995Apr19.085759.7065@uu.net>
Organization: Universität Hamburg Fachbereich Informatik
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In article <1995Apr19.085759.7065@uu.net>, kivanov@uu.net (Katrin Ivanov) writes:
> Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier.
> The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead.

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

-- 
=== Yuki Sato ===
Dept of Electrical Engineering, Universität Hamburg Fachbereich Informatik
"Tape doesn't lie at 02:14. Ears do."