From asuzuki@delphi.com Mon Aug 05 02:55:51 1996
Path: ashpoly!cascade!bigsur!delphi!asuzuki
From: asuzuki@delphi.com (Aiko Suzuki)
Newsgroups: comp.sys.m68k
Subject: [FLAME] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1996Aug05.025551.3201@delphi.com>
Date: Mon, 05 Aug 1996 02:55:51 GMT
Organization: Delphi Internet Services
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Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS.

By setting up Paula's audio DMA to double-buffer incoming 8-bit samples, the 68020 has plenty of cycles left for the Costas loop.
I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz.

Does anyone want to test on an unaccelerated Amiga 500 with 512K chip RAM?

-- 
Aiko Suzuki
Tape trading list upon request. SASE required for international mail.

From brobertson@uni-hamburg.de Tue Aug 06 03:36:51 1996
Path: ashpoly!bigsur!pacrim!jpgate!kamome!uni-hamburg!brobertson
From: brobertson@uni-hamburg.de (Bill Robertson)
Newsgroups: comp.sys.m68k
Subject: Re: [FLAME] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1996Aug06.033651.5026@uni-hamburg.de>
Date: Tue, 06 Aug 1996 03:36:51 GMT
References: <1996Aug05.025551.3201@delphi.com>
Organization: Universität Hamburg Fachbereich Informatik
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In article <1996Aug05.025551.3201@delphi.com>, asuzuki@delphi.com (Aiko Suzuki) writes:
> Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS.
> By setting up Paula's audio DMA to double-buffer incoming 8-bit samples, the 68020 has plenty of cycles left for the Costas loop.

Please make sure it's compatible with Kickstart 1.3 for those of us who haven't upgraded our A500s to 3.1 yet.

-- 
Bill Robertson -- Universität Hamburg Fachbereich Informatik
"In theory there is no difference between theory and practice."