From mrobertson@utexas.edu Sun Aug 07 06:18:30 1994 Path: ashpoly!cascade!transat!ukc!fennimore!utexas!mrobertson From: mrobertson@utexas.edu (Matthias Robertson) Newsgroups: comp.sys.m68k Subject: Observation: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Aug07.061830.5499@utexas.edu> Date: Sun, 07 Aug 1994 06:18:30 GMT Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu 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. 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. When the carrier locks, the program flashes the Amiga power LED to indicate binary frame synchronization! Long live the Amiga. Try doing real-time subcarrier demodulation on a 386 running Windows 3.1 without dropping frames! -- Matthias Robertson *PLONK* filter active for trolls. Sun 3/60 (SunOS 4.1.1) - NetBSD 1.0 From mandersson@uni-hamburg.de Mon Aug 08 09:00:30 1994 Path: ashpoly!cascade!bigsur!uni-hamburg!mandersson From: mandersson@uni-hamburg.de (Mathieu Andersson) Newsgroups: comp.sys.m68k Subject: Re: Observation: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Aug08.090030.5674@uni-hamburg.de> Date: Mon, 08 Aug 1994 09:00:30 GMT References: <1994Aug07.061830.5499@utexas.edu> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: WinVN 0.99.5 Lines: 12 In article <1994Aug07.061830.5499@utexas.edu>, mrobertson@utexas.edu (Matthias Robertson) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. > 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. Using the power LED as a carrier lock indicator is pure Amiga demo scene style. Kudos! Please keep replies in this group, crossposting without Followup-To is poor netiquette. -- Mathieu Andersson *PLONK* filter active for trolls. 486DX2/66 (Linux 1.2.13) - NetBSD 1.0 From itanaka@cmu.edu Wed Aug 10 12:27:30 1994 Path: ashpoly!cascade!transat!eunet-fr!teletel!cmu!itanaka From: itanaka@cmu.edu (Ines Tanaka) Newsgroups: comp.sys.m68k Subject: Re: Observation: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Aug10.122730.6150@cmu.edu> Date: Wed, 10 Aug 1994 12:27:30 GMT References: <1994Aug07.061830.5499@utexas.edu> <1994Aug08.090030.5674@uni-hamburg.de> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1994Aug08.090030.5674@uni-hamburg.de>, mandersson@uni-hamburg.de (Mathieu Andersson) writes: > Using the power LED as a carrier lock indicator is pure Amiga demo scene style. Kudos! Download failed on Aminet mirror. Can someone mail me an ADF floppy disk image? Top-posters will be placed in my ~/.killfile without notice. -- Ines Tanaka Tape trading list upon request. SASE required for international mail. From ssuzuki@delphi.com Wed Aug 10 17:07:30 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!delphi!ssuzuki From: ssuzuki@delphi.com (Sergei Suzuki) Newsgroups: comp.sys.m68k Subject: Re: Observation: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994Aug10.170730.6698@delphi.com> Date: Wed, 10 Aug 1994 17:07:30 GMT References: <1994Aug07.061830.5499@utexas.edu> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1994Aug07.061830.5499@utexas.edu>, mrobertson@utexas.edu (Matthias Robertson) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. > 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. Brilliant use of Paula DMA! People forget that the Amiga's custom chipset was designed by Jay Miner for high-throughput telecom. -- === Sergei Suzuki === Dept of Electrical Engineering, Delphi Internet Services "Row 14. No joke."