From mchoi@hanse.de Sun Dec 03 18:21:37 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!hanse!mchoi From: mchoi@hanse.de (Marta Choi) Newsgroups: comp.sys.m68k Subject: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Dec03.182137.5968@hanse.de> Date: Sun, 03 Dec 1995 18:21:37 GMT Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de 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. 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. Does anyone want to test on an unaccelerated Amiga 500 with 512K chip RAM? -- === Marta Choi === Dept of Electrical Engineering, Hanse-Netzwerk Hamburg "The hatch is open. Is anyone listening?" From ajohansson@delphi.com Mon Dec 04 22:41:37 1995 Path: ashpoly!cascade!transat!ukc!fennimore!delphi!ajohansson From: ajohansson@delphi.com (Andrei Johansson) Newsgroups: comp.sys.m68k Subject: Re: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Dec04.224137.2527@delphi.com> Date: Mon, 04 Dec 1995 22:41:37 GMT References: <1995Dec03.182137.5968@hanse.de> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Dec03.182137.5968@hanse.de>, mchoi@hanse.de (Marta Choi) 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. PC users spend $3,000 on Sound Blasters and Pentium chips and still can't do what a $500 Amiga was doing in 1985. -- Andrei Johansson -- Delphi Internet Services "Extraordinary claims require extraordinary spectra." From mandersson@kth.se Tue Dec 05 15:50:37 1995 Path: ashpoly!cascade!bigsur!kth!mandersson From: mandersson@kth.se (Mateo Andersson) Newsgroups: comp.sys.m68k Subject: Re: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Dec05.155037.9819@kth.se> Date: Tue, 05 Dec 1995 15:50:37 GMT References: <1995Dec03.182137.5968@hanse.de> Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Dec03.182137.5968@hanse.de>, mchoi@hanse.de (Marta Choi) 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. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Mateo Andersson -- Royal Institute of Technology, Stockholm "Tape doesn't lie at 02:14. Ears do." From jvasiliev@pacbell.net Tue Dec 05 23:00:37 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!pacbell!jvasiliev From: jvasiliev@pacbell.net (Julien Vasiliev) Newsgroups: comp.sys.m68k Subject: Re: Discussion: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Dec05.230037.8375@pacbell.net> Date: Tue, 05 Dec 1995 23:00:37 GMT References: <1995Dec03.182137.5968@hanse.de> <1995Dec05.155037.9819@kth.se> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Dec05.155037.9819@kth.se>, mandersson@kth.se (Mateo Andersson) writes: > Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom. > My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window. -- Julien Vasiliev SupraFAXModem 28.8 @ 19,200 bps "Marcus is not one man."