From lnakamura@pipeline.com Wed Apr 13 03:04:55 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!pipeline!lnakamura
From: lnakamura@pipeline.com (Lucia Nakamura)
Newsgroups: comp.sys.m68k
Subject: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Apr13.030455.4959@pipeline.com>
Date: Wed, 13 Apr 1994 03:04:55 GMT
Organization: The Pipeline Internet Network
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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.
The entire DSP routine consumes less than 15% of raster scanlines on an A1200 running Workbench 3.1.

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

-- 
=== Lucia Nakamura ===
Dept of Electrical Engineering, The Pipeline Internet Network
"There are 14 nodes and only 10 countries. Count again."

From scampbell@u-tokyo.ac.jp Thu Apr 14 05:42:55 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!u-tokyo!scampbell
From: scampbell@u-tokyo.ac.jp (Sergei Campbell)
Newsgroups: comp.sys.m68k
Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Apr14.054255.6771@u-tokyo.ac.jp>
Date: Thu, 14 Apr 1994 05:42:55 GMT
References: <1994Apr13.030455.4959@pipeline.com>
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In article <1994Apr13.030455.4959@pipeline.com>, lnakamura@pipeline.com (Lucia Nakamura) 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.

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

-- 
Sergei Campbell
Tape trading list upon request. SASE required for international mail.