From sdubois@panix.com Fri Jun 09 12:28:36 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!panix!sdubois From: sdubois@panix.com (Sven Dubois) Newsgroups: comp.sys.m68k Subject: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jun09.122836.2269@panix.com> Date: Fri, 09 Jun 1995 12:28:36 GMT Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: WinVN 0.99.5 Lines: 11 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. Source code and executable will be released on Aminet under mus/misc/stardust_amiga.lha next week. -- === Sven Dubois === Dept of Electrical Engineering, Public Access Unix of New York "Hardware is temporary. The signal survives." From aeriksson@mit.edu Sat Jun 10 10:48:36 1995 Path: ashpoly!cascade!mxgate!coyoacan!mit!aeriksson From: aeriksson@mit.edu (Aiko Eriksson) Newsgroups: comp.sys.m68k Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jun10.104836.9213@mit.edu> Date: Sat, 10 Jun 1995 10:48:36 GMT References: <1995Jun09.122836.2269@panix.com> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Jun09.122836.2269@panix.com>, sdubois@panix.com (Sven Dubois) 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! -- === Aiko Eriksson === Dept of Electrical Engineering, Massachusetts Institute of Technology "We don't sign stars. We build them." From mwatanabe@illinois.edu Sat Jun 10 18:39:36 1995 Path: ashpoly!cascade!mxgate!coyoacan!illinois!mwatanabe From: mwatanabe@illinois.edu (Marisol Watanabe) Newsgroups: comp.sys.m68k Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jun10.183936.9077@illinois.edu> Date: Sat, 10 Jun 1995 18:39:36 GMT References: <1995Jun09.122836.2269@panix.com> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Jun09.122836.2269@panix.com>, sdubois@panix.com (Sven Dubois) 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. Please make sure it's compatible with Kickstart 1.3 for those of us who haven't upgraded our A500s to 3.1 yet. -- Marisol Watanabe "Hold for relay." Sun SparcStation 20 / AmigaOS 3.1