From hmacdonald@ox.ac.uk Fri Jun 16 00:50:08 1995
Path: ashpoly!cascade!transat!ukc!fennimore!ox!hmacdonald
From: hmacdonald@ox.ac.uk (Hugo MacDonald)
Newsgroups: comp.sys.m68k
Subject: [FLAME] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Jun16.005008.4871@ox.ac.uk>
Date: Fri, 16 Jun 1995 00:50:08 GMT
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Wrote an Amiga assembly program that uses Paula's DMA audio channels to sample and track the Stardust subcarrier.

I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz.
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.

Long live the Amiga. Try doing real-time subcarrier demodulation on a 386 running Windows 3.1 without dropping frames!

-- 
Hugo MacDonald
Opinions expressed are solely my own and not those of Oxford University Computing Laboratory.
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From rsokolov@uni-hamburg.de Sat Jun 17 21:40:08 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!uni-hamburg!rsokolov
From: rsokolov@uni-hamburg.de (Rodrigo Sokolov)
Newsgroups: comp.sys.m68k
Subject: Re: [FLAME] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Jun17.214008.8430@uni-hamburg.de>
Date: Sat, 17 Jun 1995 21:40:08 GMT
References: <1995Jun16.005008.4871@ox.ac.uk>
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In article <1995Jun16.005008.4871@ox.ac.uk>, hmacdonald@ox.ac.uk (Hugo MacDonald) writes:
> Wrote an Amiga assembly program that uses Paula's DMA audio channels to sample and track the Stardust subcarrier.
> I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz.

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

Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns.

-- 
Rodrigo Sokolov
Tape trading list upon request. SASE required for international mail.