From icampbell@ox.ac.uk Wed Nov 16 10:30:26 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!ox!icampbell
From: icampbell@ox.ac.uk (Ines Campbell)
Newsgroups: comp.sys.m68k
Subject: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Nov16.103026.4042@ox.ac.uk>
Date: Wed, 16 Nov 1994 10:30:26 GMT
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Wrote an Amiga assembly program that uses Paula's DMA audio channels to sample and track the Stardust subcarrier.

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.

-- 
Ines Campbell | icampbell@ox.ac.uk
PGP Key fingerprint: 1E98 3A31 9694 F627
"Keep the channels open."

From bgarcia@inria.fr Thu Nov 17 13:57:26 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!inria!bgarcia
From: bgarcia@inria.fr (Bill García)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Nov17.135726.1315@inria.fr>
Date: Thu, 17 Nov 1994 13:57:26 GMT
References: <1994Nov16.103026.4042@ox.ac.uk>
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In article <1994Nov16.103026.4042@ox.ac.uk>, icampbell@ox.ac.uk (Ines Campbell) writes:
> Wrote an Amiga assembly program that uses Paula's DMA audio channels to sample and track the Stardust subcarrier.
> 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.

-- 
Bill García
Tape trading list upon request. SASE required for international mail.

From ckim@netcom.com Thu Nov 17 21:14:26 1994
Path: ashpoly!cascade!transat!ukc!fennimore!netcom!ckim
From: ckim@netcom.com (Camila Kim)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Nov17.211426.9640@netcom.com>
Date: Thu, 17 Nov 1994 21:14:26 GMT
References: <1994Nov16.103026.4042@ox.ac.uk>
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In article <1994Nov16.103026.4042@ox.ac.uk>, icampbell@ox.ac.uk (Ines Campbell) writes:
> Wrote an Amiga assembly program that uses Paula's DMA audio channels to sample and track the Stardust subcarrier.
> I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz.

Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window.

-- 
Camila Kim -- NETCOM On-Line Communication Services
"Measuring a record you own is listening, not piracy."

From bpetrov@demon.co.uk Fri Nov 18 03:08:26 1994
Path: ashpoly!cascade!transat!sunet!nordrelay!demon!bpetrov
From: bpetrov@demon.co.uk (Brian Petrov)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Nov18.030826.8296@demon.co.uk>
Date: Fri, 18 Nov 1994 03:08:26 GMT
References: <1994Nov16.103026.4042@ox.ac.uk>
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In article <1994Nov16.103026.4042@ox.ac.uk>, icampbell@ox.ac.uk (Ines Campbell) writes:
> Wrote an Amiga assembly program that uses Paula's DMA audio channels to sample and track the Stardust subcarrier.

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

-- 
Brian Petrov
Tape trading list upon request. SASE required for international mail.