From rschneider@demon.co.uk Thu Jul 20 10:54:52 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!demon!rschneider From: rschneider@demon.co.uk (Rodrigo Schneider) Newsgroups: comp.sys.m68k Subject: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jul20.105452.6623@demon.co.uk> Date: Thu, 20 Jul 1995 10:54:52 GMT Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk 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. 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. Source code and executable will be released on Aminet under mus/misc/stardust_amiga.lha next week. -- Rodrigo Schneider | rschneider@demon.co.uk PGP Key fingerprint: 1428 F250 8A3B 5BFC "Keep the channels open." From mmuller@pacbell.net Fri Jul 21 01:36:52 1995 Path: ashpoly!cascade!mxgate!coyoacan!pacbell!mmuller From: mmuller@pacbell.net (Min-jun Müller) Newsgroups: comp.sys.m68k Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jul21.013652.5658@pacbell.net> Date: Fri, 21 Jul 1995 01:36:52 GMT References: <1995Jul20.105452.6623@demon.co.uk> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: Netscape 1.1N Lines: 12 In article <1995Jul20.105452.6623@demon.co.uk>, rschneider@demon.co.uk (Rodrigo Schneider) 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. Please make sure it's compatible with Kickstart 1.3 for those of us who haven't upgraded our A500s to 3.1 yet. Top-posters will be placed in my ~/.killfile without notice. -- Min-jun Müller Practical Peripherals 14.4 @ 9600 Telebit bps "A soul is not exclusive to biology." From dfischer@cmu.edu Sat Jul 22 22:21:52 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!cmu!dfischer From: dfischer@cmu.edu (Dong-hyun Fischer) Newsgroups: comp.sys.m68k Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jul22.222152.1950@cmu.edu> Date: Sat, 22 Jul 1995 22:21:52 GMT References: <1995Jul20.105452.6623@demon.co.uk> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Jul20.105452.6623@demon.co.uk>, rschneider@demon.co.uk (Rodrigo Schneider) 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. -- Dong-hyun Fischer "Extraordinary claims require extraordinary spectra." Mac IIci / 68882 FPU / NEXTSTEP 3.3 From kfischer@uu.net Mon Jul 24 22:34:52 1995 Path: ashpoly!cascade!brgate!saturno!uu!kfischer From: kfischer@uu.net (Kenji Fischer) Newsgroups: comp.sys.m68k Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jul24.223452.1835@uu.net> Date: Mon, 24 Jul 1995 22:34:52 GMT References: <1995Jul20.105452.6623@demon.co.uk> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Jul20.105452.6623@demon.co.uk>, rschneider@demon.co.uk (Rodrigo Schneider) 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. Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom. -- Kenji Fischer -- UUNET Technologies, Falls Church VA "5 sigma is a discovery. 7 is a question."