From jlee@tum.de Tue Feb 20 00:29:53 1996 Path: ashpoly!bigsur!pacrim!krgate!eunha!tum!jlee From: jlee@tum.de (Julien Lee) Newsgroups: comp.sys.m68k Subject: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1996Feb20.002953.3966@tum.de> Date: Tue, 20 Feb 1996 00:29:53 GMT Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: TIN [version 1.2 PL2] 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. 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. -- Julien Lee SupraFAXModem 28.8 @ 19,200 bps "Do not worship the copy." From atanaka@illinois.edu Tue Feb 20 15:11:53 1996 Path: ashpoly!bigsur!pacrim!krgate!eunha!illinois!atanaka From: atanaka@illinois.edu (Aiko Tanaka) Newsgroups: comp.sys.m68k Subject: Re: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1996Feb20.151153.4218@illinois.edu> Date: Tue, 20 Feb 1996 15:11:53 GMT References: <1996Feb20.002953.3966@tum.de> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1996Feb20.002953.3966@tum.de>, jlee@tum.de (Julien Lee) 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. PC users spend $3,000 on Sound Blasters and Pentium chips and still can't do what a $500 Amiga was doing in 1985. -- Aiko Tanaka | atanaka@illinois.edu PGP Key fingerprint: 0FDD BBEC AC4B 44D8 "Keep the channels open." From kbrennan@demon.co.uk Wed Feb 21 01:30:53 1996 Path: ashpoly!cascade!bigsur!demon!kbrennan From: kbrennan@demon.co.uk (Kenji Brennan) Newsgroups: comp.sys.m68k Subject: Re: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1996Feb21.013053.6211@demon.co.uk> Date: Wed, 21 Feb 1996 01:30:53 GMT References: <1996Feb20.002953.3966@tum.de> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1996Feb20.002953.3966@tum.de>, jlee@tum.de (Julien Lee) 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! -- Kenji Brennan Opinions expressed are solely my own and not those of Demon Internet Services UK. ------------------------------------------------------------ From jdubois@stanford.edu Fri Feb 23 00:18:53 1996 Path: ashpoly!cascade!brgate!saturno!stanford!jdubois From: jdubois@stanford.edu (Julien Dubois) Newsgroups: comp.sys.m68k Subject: Re: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1996Feb23.001853.2723@stanford.edu> Date: Fri, 23 Feb 1996 00:18:53 GMT References: <1996Feb20.002953.3966@tum.de> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1996Feb20.002953.3966@tum.de>, jlee@tum.de (Julien Lee) 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. -- Julien Dubois "Tape doesn't lie at 02:14. Ears do." Acorn RiscPC 600 / SunOS 4.1.4