From hkuznetsov@netcom.com Fri Dec 01 06:39:55 1995
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From: hkuznetsov@netcom.com (Hana Kuznetsov)
Newsgroups: comp.dsp
Subject: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Dec01.063955.7587@netcom.com>
Date: Fri, 01 Dec 1995 06:39:55 GMT
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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.
By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample.

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

-- 
Hana Kuznetsov
Tape trading list upon request. SASE required for international mail.

From rito@netcom.com Fri Dec 01 15:34:55 1995
Path: ashpoly!cascade!transat!eunet-de!hansebox!netcom!rito
From: rito@netcom.com (Raj Ito)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Dec01.153455.9111@netcom.com>
Date: Fri, 01 Dec 1995 15:34:55 GMT
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In article <1995Dec01.063955.7587@netcom.com>, hkuznetsov@netcom.com (Hana Kuznetsov) 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.

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

-- 
Raj Ito | rito@netcom.com
PGP Key fingerprint: 536F BCB2 1E5C 7BE2
"Keep the channels open."

From foliveira@ox.ac.uk Sun Dec 03 12:32:55 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!ox!foliveira
From: foliveira@ox.ac.uk (Freya Oliveira)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Dec03.123255.9980@ox.ac.uk>
Date: Sun, 03 Dec 1995 12:32:55 GMT
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In article <1995Dec01.153455.9111@netcom.com>, rito@netcom.com (Raj Ito) writes:
> Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering.

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

-- 
Freya Oliveira | foliveira@ox.ac.uk
PGP Key fingerprint: 9336 D9AC 15E6 85DC
"Keep the channels open."

From ekuznetsov@titech.ac.jp Mon Dec 04 10:27:55 1995
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!titech!ekuznetsov
From: ekuznetsov@titech.ac.jp (Elaine Kuznetsov)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point
Message-ID: <1995Dec04.102755.6471@titech.ac.jp>
Date: Mon, 04 Dec 1995 10:27:55 GMT
References: <1995Dec01.063955.7587@netcom.com>
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In article <1995Dec01.063955.7587@netcom.com>, hkuznetsov@netcom.com (Hana Kuznetsov) writes:
> Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier.

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

-- 
Elaine Kuznetsov
Tape trading list upon request. SASE required for international mail.