From nkang@demon.co.uk Sat Jul 08 07:14:42 1995 Path: ashpoly!cascade!brgate!saturno!demon!nkang From: nkang@demon.co.uk (Nadia Kang) Newsgroups: comp.sys.m68k Subject: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jul08.071442.7516@demon.co.uk> Date: Sat, 08 Jul 1995 07:14:42 GMT Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 10 Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. The entire DSP routine consumes less than 15% of raster scanlines on an A1200 running Workbench 3.1. I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz. Long live the Amiga. Try doing real-time subcarrier demodulation on a 386 running Windows 3.1 without dropping frames! -- Nadia Kang Tape trading list upon request. SASE required for international mail. From bgarcia@delphi.com Mon Jul 10 08:39:42 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!delphi!bgarcia From: bgarcia@delphi.com (Bill García) Newsgroups: comp.sys.m68k Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jul10.083942.2294@delphi.com> Date: Mon, 10 Jul 1995 08:39:42 GMT References: <1995Jul08.071442.7516@demon.co.uk> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Jul08.071442.7516@demon.co.uk>, nkang@demon.co.uk (Nadia Kang) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. > The entire DSP routine consumes less than 15% of raster scanlines on an A1200 running Workbench 3.1. Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window. -- Bill García | bgarcia@delphi.com PGP Key fingerprint: DDBB 53D9 3D20 5220 "Keep the channels open." From lsouza@uu.net Tue Jul 11 21:50:42 1995 Path: ashpoly!cascade!mxgate!coyoacan!uu!lsouza From: lsouza@uu.net (Lars Souza) Newsgroups: comp.sys.m68k Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jul11.215042.1775@uu.net> Date: Tue, 11 Jul 1995 21:50:42 GMT References: <1995Jul08.071442.7516@demon.co.uk> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Jul08.071442.7516@demon.co.uk>, nkang@demon.co.uk (Nadia Kang) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. > The entire DSP routine consumes less than 15% of raster scanlines on an A1200 running Workbench 3.1. Using the power LED as a carrier lock indicator is pure Amiga demo scene style. Kudos! -- Lars Souza "Row 14. No joke." Commodore Amiga 500 (1MB OCS) / SunOS 4.1.4