From tito@ox.ac.uk Fri Aug 04 01:50:47 1995
Path: ashpoly!cascade!mxgate!coyoacan!ox!tito
From: tito@ox.ac.uk (Tyler Ito)
Newsgroups: comp.sys.m68k
Subject: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Aug04.015047.5976@ox.ac.uk>
Date: Fri, 04 Aug 1995 01:50:47 GMT
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Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS.

I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz.
When the carrier locks, the program flashes the Amiga power LED to indicate binary frame synchronization!

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

-- 
Tyler Ito | tito@ox.ac.uk
PGP Key fingerprint: 9B87 BA4F 0A36 6EB6
"Keep the channels open."

From mmoreau@earthlink.net Sat Aug 05 12:47:47 1995
Path: ashpoly!cascade!transat!ukc!fennimore!earthlink!mmoreau
From: mmoreau@earthlink.net (Morag Moreau)
Newsgroups: comp.sys.m68k
Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Aug05.124747.2147@earthlink.net>
Date: Sat, 05 Aug 1995 12:47:47 GMT
References: <1995Aug04.015047.5976@ox.ac.uk>
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In article <1995Aug04.015047.5976@ox.ac.uk>, tito@ox.ac.uk (Tyler Ito) writes:
> Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS.
> 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!

My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise!

-- 
=== Morag Moreau ===
Dept of Electrical Engineering, EarthLink Network
"Tape doesn't lie at 02:14. Ears do."