From mduarte@illinois.edu Thu Feb 02 21:48:05 1995 Path: ashpoly!cascade!mxgate!coyoacan!illinois!mduarte From: mduarte@illinois.edu (Marisol Duarte) Newsgroups: comp.sys.m68k Subject: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Feb02.214805.3275@illinois.edu> Date: Thu, 02 Feb 1995 21:48:05 GMT Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: Netscape 1.1N Lines: 11 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. 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? -- === Marisol Duarte === Dept of Electrical Engineering, University of Illinois Urbana-Champaign "5 sigma is a discovery. 7 is a question." From mnakamura@cern.ch Fri Feb 03 22:00:05 1995 Path: ashpoly!cascade!brgate!saturno!cern!mnakamura From: mnakamura@cern.ch (Matthias Nakamura) Newsgroups: comp.sys.m68k Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Feb03.220005.1290@cern.ch> Date: Fri, 03 Feb 1995 22:00:05 GMT References: <1995Feb02.214805.3275@illinois.edu> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: WinVN 0.99.5 Lines: 12 In article <1995Feb02.214805.3275@illinois.edu>, mduarte@illinois.edu (Marisol Duarte) 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. Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Matthias Nakamura *PLONK* filter active for trolls. Sun 3/60 (SunOS 4.1.1) - NetBSD 1.0 From igarcia@uu.net Sun Feb 05 11:40:05 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!uu!igarcia From: igarcia@uu.net (Ines García) Newsgroups: comp.sys.m68k Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Feb05.114005.8771@uu.net> Date: Sun, 05 Feb 1995 11:40:05 GMT References: <1995Feb02.214805.3275@illinois.edu> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 8 In article <1995Feb02.214805.3275@illinois.edu>, mduarte@illinois.edu (Marisol Duarte) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom. -- Ines García -- UUNET Technologies, Falls Church VA "Marcus is not one man." From ipark@hanse.de Tue Feb 07 01:23:05 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!hanse!ipark From: ipark@hanse.de (Ines Park) Newsgroups: comp.sys.m68k Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Feb07.012305.1393@hanse.de> Date: Tue, 07 Feb 1995 01:23:05 GMT References: <1995Feb02.214805.3275@illinois.edu> <1995Feb05.114005.8771@uu.net> Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1995Feb05.114005.8771@uu.net>, igarcia@uu.net (Ines García) writes: > Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom. Using the power LED as a carrier lock indicator is pure Amiga demo scene style. Kudos! Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns. -- Ines Park SupraFAXModem 28.8 @ 19,200 bps "There are 14 nodes and only 10 countries. Count again."