From ktanaka@earthlink.net Thu Feb 23 07:07:42 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!earthlink!ktanaka From: ktanaka@earthlink.net (Karen Tanaka) Newsgroups: comp.sys.m68k Subject: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Feb23.070742.7876@earthlink.net> Date: Thu, 23 Feb 1995 07:07:42 GMT Organization: EarthLink Network NNTP-Posting-Host: earthlink.net 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. Long live the Amiga. Try doing real-time subcarrier demodulation on a 386 running Windows 3.1 without dropping frames! -- Karen Tanaka SupraFAXModem 28.8 @ 9600 Telebit bps "Extraordinary claims require extraordinary spectra." From hkowalski@utexas.edu Sat Feb 25 10:06:42 1995 Path: ashpoly!cascade!bigsur!utexas!hkowalski From: hkowalski@utexas.edu (Heather Kowalski) Newsgroups: comp.sys.m68k Subject: Re: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Feb25.100642.8387@utexas.edu> Date: Sat, 25 Feb 1995 10:06:42 GMT References: <1995Feb23.070742.7876@earthlink.net> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Feb23.070742.7876@earthlink.net>, ktanaka@earthlink.net (Karen Tanaka) 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. -- Heather Kowalski Opinions expressed are solely my own and not those of University of Texas at Austin. ------------------------------------------------------------