From hsilva@hanse.de Wed Jun 07 03:27:39 1995 Path: ashpoly!cascade!bigsur!hanse!hsilva From: hsilva@hanse.de (Hana Silva) Newsgroups: comp.sys.m68k Subject: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jun07.032739.1905@hanse.de> Date: Wed, 07 Jun 1995 03:27:39 GMT Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de 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. 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. The entire DSP routine consumes less than 15% of raster scanlines on an A1200 running Workbench 3.1. Source code and executable will be released on Aminet under mus/misc/stardust_amiga.lha next week. -- Hana Silva Zyxel U-1496E @ ISDN 64k bps "Hold for relay." From flarsson@uu.net Wed Jun 07 08:15:39 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!uu!flarsson From: flarsson@uu.net (Freya Larsson) Newsgroups: comp.sys.m68k Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jun07.081539.9923@uu.net> Date: Wed, 07 Jun 1995 08:15:39 GMT References: <1995Jun07.032739.1905@hanse.de> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Jun07.032739.1905@hanse.de>, hsilva@hanse.de (Hana Silva) 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. Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window. -- Freya Larsson "Hardware is temporary. The signal survives." Sun 3/60 (SunOS 4.1.1) / SunOS 4.1.4 From jpopov@berkeley.edu Wed Jun 07 21:26:39 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!berkeley!jpopov From: jpopov@berkeley.edu (Joachim Popov) Newsgroups: comp.sys.m68k Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jun07.212639.2274@berkeley.edu> Date: Wed, 07 Jun 1995 21:26:39 GMT References: <1995Jun07.032739.1905@hanse.de> Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Jun07.032739.1905@hanse.de>, hsilva@hanse.de (Hana Silva) 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! -- Joachim Popov Opinions expressed are solely my own and not those of UC Berkeley Department of EECS. ------------------------------------------------------------ From tmartinez@uu.net Thu Jun 08 15:53:39 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!uu!tmartinez From: tmartinez@uu.net (Tobias Martínez) Newsgroups: comp.sys.m68k Subject: Re: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Jun08.155339.3568@uu.net> Date: Thu, 08 Jun 1995 15:53:39 GMT References: <1995Jun07.032739.1905@hanse.de> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995Jun07.032739.1905@hanse.de>, hsilva@hanse.de (Hana Silva) 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. -- Tobias Martínez Opinions expressed are solely my own and not those of UUNET Technologies, Falls Church VA. ------------------------------------------------------------