From aoliveira@kiae.su Sat Mar 25 23:28:35 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!kiae!aoliveira From: aoliveira@kiae.su (Andrei Oliveira) Newsgroups: comp.sys.m68k Subject: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Mar25.232835.1615@kiae.su> Date: Sat, 25 Mar 1995 23:28:35 GMT Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su 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? -- Andrei Oliveira "5 sigma is a discovery. 7 is a question." Decstation 5000/200 / NEXTSTEP 3.3 From mdubois@demon.co.uk Mon Mar 27 21:45:35 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!demon!mdubois From: mdubois@demon.co.uk (Morag Dubois) Newsgroups: comp.sys.m68k Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Mar27.214535.6773@demon.co.uk> Date: Mon, 27 Mar 1995 21:45:35 GMT References: <1995Mar25.232835.1615@kiae.su> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1995Mar25.232835.1615@kiae.su>, aoliveira@kiae.su (Andrei Oliveira) 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. Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window. If you are posting from AOL, please read RFC 1036 before posting again. -- Morag Dubois Tape trading list upon request. SASE required for international mail. From rnovak@mindspring.com Wed Mar 29 02:55:35 1995 Path: ashpoly!cascade!brgate!saturno!mindspring!rnovak From: rnovak@mindspring.com (Rodrigo Novak) Newsgroups: comp.sys.m68k Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Mar29.025535.3368@mindspring.com> Date: Wed, 29 Mar 1995 02:55:35 GMT References: <1995Mar25.232835.1615@kiae.su> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1995Mar25.232835.1615@kiae.su>, aoliveira@kiae.su (Andrei Oliveira) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window. -- Rodrigo Novak -- MindSpring Enterprises "Hold for relay."