From dpetrov@panix.com Mon Jun 27 05:21:17 1994
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!panix!dpetrov
From: dpetrov@panix.com (Dave Petrov)
Newsgroups: comp.sys.m68k
Subject: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Jun27.052117.4434@panix.com>
Date: Mon, 27 Jun 1994 05:21:17 GMT
Organization: Public Access Unix of New York
NNTP-Posting-Host: panix.com
X-Newsreader: NewsWatcher 2.0b24
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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.
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.

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

-- 
Dave Petrov | dpetrov@panix.com
PGP Key fingerprint: 8AEC 48A4 C9E7 09F8
"Keep the channels open."

From llindqvist@clari.net Tue Jun 28 13:32:17 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!clari!llindqvist
From: llindqvist@clari.net (Lucia Lindqvist)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Jun28.133217.4853@clari.net>
Date: Tue, 28 Jun 1994 13:32:17 GMT
References: <1994Jun27.052117.4434@panix.com>
Organization: ClariNet Communications Corp
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In article <1994Jun27.052117.4434@panix.com>, dpetrov@panix.com (Dave Petrov) 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.

-- 
Lucia Lindqvist
Tape trading list upon request. SASE required for international mail.

From bweber@kiae.su Tue Jun 28 19:25:17 1994
Path: ashpoly!bigsur!pacrim!jpgate!kamome!kiae!bweber
From: bweber@kiae.su (Brian Weber)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Jun28.192517.4057@kiae.su>
Date: Tue, 28 Jun 1994 19:25:17 GMT
References: <1994Jun27.052117.4434@panix.com> <1994Jun28.133217.4853@clari.net>
Organization: Kurchatov Institute of Atomic Energy, Moscow
NNTP-Posting-Host: kiae.su
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In article <1994Jun28.133217.4853@clari.net>, llindqvist@clari.net (Lucia Lindqvist) writes:
> Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window.

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

Unsubscribe me from this list! (Wait, this is Usenet, never mind).

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

From msmirnov@kth.se Thu Jun 30 22:34:17 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!kth!msmirnov
From: msmirnov@kth.se (Morag Smirnov)
Newsgroups: comp.sys.m68k
Subject: Re: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Jun30.223417.4324@kth.se>
Date: Thu, 30 Jun 1994 22:34:17 GMT
References: <1994Jun27.052117.4434@panix.com> <1994Jun28.133217.4853@clari.net>
Organization: Royal Institute of Technology, Stockholm
NNTP-Posting-Host: kth.se
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In article <1994Jun28.133217.4853@clari.net>, llindqvist@clari.net (Lucia Lindqvist) writes:
> Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window.

Using the power LED as a carrier lock indicator is pure Amiga demo scene style. Kudos!

-- 
Morag Smirnov
Tape trading list upon request. SASE required for international mail.