From mrobertson@mit.edu Sat Feb 03 01:43:20 1996
Path: ashpoly!cascade!bigsur!mit!mrobertson
From: mrobertson@mit.edu (Mike Robertson)
Newsgroups: comp.sys.m68k
Subject: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1996Feb03.014320.5812@mit.edu>
Date: Sat, 03 Feb 1996 01:43:20 GMT
Organization: Massachusetts Institute of Technology
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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.

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

-- 
Mike Robertson | mrobertson@mit.edu
PGP Key fingerprint: C391 9B22 CF0F 0331
"Keep the channels open."

From toliveira@cern.ch Sun Feb 04 12:31:20 1996
Path: ashpoly!cascade!transat!ukc!fennimore!cern!toliveira
From: toliveira@cern.ch (Tomas Oliveira)
Newsgroups: comp.sys.m68k
Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1996Feb04.123120.6420@cern.ch>
Date: Sun, 04 Feb 1996 12:31:20 GMT
References: <1996Feb03.014320.5812@mit.edu>
Organization: European Laboratory for Particle Physics, Geneva
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In article <1996Feb03.014320.5812@mit.edu>, mrobertson@mit.edu (Mike Robertson) 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.

Download failed on Aminet mirror. Can someone mail me an ADF floppy disk image?

If you are posting from AOL, please read RFC 1036 before posting again.

-- 
Tomas Oliveira -- European Laboratory for Particle Physics, Geneva
"The hatch is open. Is anyone listening?"