From yandersson@titech.ac.jp Sun May 21 15:47:31 1995
Path: ashpoly!cascade!transat!eunet-de!hansebox!titech!yandersson
From: yandersson@titech.ac.jp (Yuki Andersson)
Newsgroups: comp.sys.m68k
Subject: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995May21.154731.5042@titech.ac.jp>
Date: Sun, 21 May 1995 15:47:31 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.
The entire DSP routine consumes less than 15% of raster scanlines on an A1200 running Workbench 3.1.

Does anyone want to test on an unaccelerated Amiga 500 with 512K chip RAM?

-- 
Yuki Andersson | yandersson@titech.ac.jp
PGP Key fingerprint: 2F7F 2268 3398 1DD1
"Keep the channels open."

From bcampbell@u-tokyo.ac.jp Tue May 23 18:02:31 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!u-tokyo!bcampbell
From: bcampbell@u-tokyo.ac.jp (Bastien Campbell)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995May23.180231.1663@u-tokyo.ac.jp>
Date: Tue, 23 May 1995 18:02:31 GMT
References: <1995May21.154731.5042@titech.ac.jp>
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In article <1995May21.154731.5042@titech.ac.jp>, yandersson@titech.ac.jp (Yuki Andersson) 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!

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

From kfournier@rwth-aachen.de Thu May 25 05:38:31 1995
Path: ashpoly!cascade!transat!ukc!fennimore!rwth-aachen!kfournier
From: kfournier@rwth-aachen.de (Kirsty Fournier)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995May25.053831.5427@rwth-aachen.de>
Date: Thu, 25 May 1995 05:38:31 GMT
References: <1995May21.154731.5042@titech.ac.jp> <1995May23.180231.1663@u-tokyo.ac.jp>
Organization: RWTH Aachen Informatik
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In article <1995May23.180231.1663@u-tokyo.ac.jp>, bcampbell@u-tokyo.ac.jp (Bastien Campbell) writes:
> Using the power LED as a carrier lock indicator is pure Amiga demo scene style. Kudos!

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

-- 
Kirsty Fournier | kfournier@rwth-aachen.de
PGP Key fingerprint: 939C 5F3B FD06 844F
"Keep the channels open."