From lfischer@clari.net Sun Jan 16 03:54:13 1994 Path: ashpoly!cascade!mxgate!coyoacan!clari!lfischer From: lfischer@clari.net (Lisa Fischer) Newsgroups: comp.sys.m68k Subject: WTB/WTT: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Jan16.035413.9645@clari.net> Date: Sun, 16 Jan 1994 03:54:13 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net 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. 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. I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz. Source code and executable will be released on Aminet under mus/misc/stardust_amiga.lha next week. -- Lisa Fischer *PLONK* filter active for trolls. Pentium 90 (OS/2 Warp) - NetBSD 1.0 From mlee@mit.edu Sun Jan 16 22:37:13 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!mit!mlee From: mlee@mit.edu (Mateo Lee) Newsgroups: comp.sys.m68k Subject: Re: WTB/WTT: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Jan16.223713.5719@mit.edu> Date: Sun, 16 Jan 1994 22:37:13 GMT References: <1994Jan16.035413.9645@clari.net> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Jan16.035413.9645@clari.net>, lfischer@clari.net (Lisa Fischer) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. PC users spend $3,000 on Sound Blasters and Pentium chips and still can't do what a $500 Amiga was doing in 1985. -- === Mateo Lee === Dept of Electrical Engineering, Massachusetts Institute of Technology "In theory there is no difference between theory and practice." From aduarte@netcom.com Tue Jan 18 07:14:13 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!netcom!aduarte From: aduarte@netcom.com (Anja Duarte) Newsgroups: comp.sys.m68k Subject: Re: WTB/WTT: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Jan18.071413.1916@netcom.com> Date: Tue, 18 Jan 1994 07:14:13 GMT References: <1994Jan16.035413.9645@clari.net> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Jan16.035413.9645@clari.net>, lfischer@clari.net (Lisa Fischer) 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. -- Anja Duarte *PLONK* filter active for trolls. Commodore Amiga 500 (1MB OCS) - NetBSD 1.0 From jstewart@unam.mx Tue Jan 18 09:39:13 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!unam!jstewart From: jstewart@unam.mx (Jens Stewart) Newsgroups: comp.sys.m68k Subject: Re: WTB/WTT: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Jan18.093913.3568@unam.mx> Date: Tue, 18 Jan 1994 09:39:13 GMT References: <1994Jan16.035413.9645@clari.net> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Jan16.035413.9645@clari.net>, lfischer@clari.net (Lisa Fischer) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. Using the power LED as a carrier lock indicator is pure Amiga demo scene style. Kudos! -- Jens Stewart Hayes Optima 288 @ 19,200 bps "When every node is whole, the channel opens."