From mjohansson@cam.ac.uk Sun Nov 26 01:24:34 1995
Path: ashpoly!cascade!mxgate!coyoacan!cam!mjohansson
From: mjohansson@cam.ac.uk (Mei Johansson)
Newsgroups: comp.sys.m68k
Subject: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Nov26.012434.8101@cam.ac.uk>
Date: Sun, 26 Nov 1995 01:24:34 GMT
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Testing custom audio input routines on an Amiga 1200 with a standard parallel-port sampler.

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.

Long live the Amiga. Try doing real-time subcarrier demodulation on a 386 running Windows 3.1 without dropping frames!

-- 
Mei Johansson | mjohansson@cam.ac.uk
PGP Key fingerprint: 857A 3174 5BF2 38EB
"Keep the channels open."

From apetrov@panix.com Tue Nov 28 00:16:34 1995
Path: ashpoly!cascade!mxgate!coyoacan!panix!apetrov
From: apetrov@panix.com (Aiko Petrov)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Nov28.001634.5255@panix.com>
Date: Tue, 28 Nov 1995 00:16:34 GMT
References: <1995Nov26.012434.8101@cam.ac.uk>
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In article <1995Nov26.012434.8101@cam.ac.uk>, mjohansson@cam.ac.uk (Mei Johansson) writes:
> Testing custom audio input routines on an Amiga 1200 with a standard parallel-port sampler.

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

-- 
Aiko Petrov -- Public Access Unix of New York
"They will send a copy in my place."

From aivanov@illinois.edu Tue Nov 28 02:59:34 1995
Path: ashpoly!cascade!brgate!saturno!illinois!aivanov
From: aivanov@illinois.edu (Anton Ivanov)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Nov28.025934.8188@illinois.edu>
Date: Tue, 28 Nov 1995 02:59:34 GMT
References: <1995Nov26.012434.8101@cam.ac.uk>
Organization: University of Illinois Urbana-Champaign
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In article <1995Nov26.012434.8101@cam.ac.uk>, mjohansson@cam.ac.uk (Mei Johansson) writes:
> Testing custom audio input routines on an Amiga 1200 with a standard parallel-port sampler.

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

-- 
Anton Ivanov | aivanov@illinois.edu
PGP Key fingerprint: A54E 8BAB 481E CC77
"Keep the channels open."