From abrennan@tum.de Mon Sep 18 05:18:23 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!tum!abrennan
From: abrennan@tum.de (Astrid Brennan)
Newsgroups: comp.sys.m68k
Subject: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Sep18.051823.9861@tum.de>
Date: Mon, 18 Sep 1995 05:18:23 GMT
Organization: Technische Universität München
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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!

-- 
Astrid Brennan | abrennan@tum.de
PGP Key fingerprint: 41E9 584F 1BCC 0365
"Keep the channels open."

From mcampbell@u-tokyo.ac.jp Wed Sep 20 05:30:23 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!u-tokyo!mcampbell
From: mcampbell@u-tokyo.ac.jp (Mathieu Campbell)
Newsgroups: comp.sys.m68k
Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Sep20.053023.8877@u-tokyo.ac.jp>
Date: Wed, 20 Sep 1995 05:30:23 GMT
References: <1995Sep18.051823.9861@tum.de>
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In article <1995Sep18.051823.9861@tum.de>, abrennan@tum.de (Astrid Brennan) 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.

Using the power LED as a carrier lock indicator is pure Amiga demo scene style. Kudos!

-- 
Mathieu Campbell | mcampbell@u-tokyo.ac.jp
PGP Key fingerprint: 07B0 0BDF 1093 905F
"Keep the channels open."