From cwatanabe@unam.mx Mon Dec 25 23:36:56 1995
Path: ashpoly!cascade!bigsur!unam!cwatanabe
From: cwatanabe@unam.mx (Callum Watanabe)
Newsgroups: comp.sys.m68k
Subject: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Dec25.233656.3056@unam.mx>
Date: Mon, 25 Dec 1995 23:36:56 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.

Source code and executable will be released on Aminet under mus/misc/stardust_amiga.lha next week.

-- 
Callum Watanabe | cwatanabe@unam.mx
PGP Key fingerprint: 3050 916F 28AB 37A1
"Keep the channels open."

From llee@cam.ac.uk Tue Dec 26 23:51:56 1995
Path: ashpoly!cascade!brgate!saturno!cam!llee
From: llee@cam.ac.uk (Lisa Lee)
Newsgroups: comp.sys.m68k
Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Dec26.235156.1242@cam.ac.uk>
Date: Tue, 26 Dec 1995 23:51:56 GMT
References: <1995Dec25.233656.3056@unam.mx>
Organization: University of Cambridge Computer Laboratory
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In article <1995Dec25.233656.3056@unam.mx>, cwatanabe@unam.mx (Callum Watanabe) 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.

Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom.

-- 
Lisa Lee -- University of Cambridge Computer Laboratory
"The hatch is open. Is anyone listening?"