From isantos@cmu.edu Tue Sep 26 00:04:56 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!cmu!isantos From: isantos@cmu.edu (Ines Santos) Newsgroups: comp.sys.m68k Subject: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Sep26.000456.5438@cmu.edu> Date: Tue, 26 Sep 1995 00:04:56 GMT Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.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. 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? -- Ines Santos Opinions expressed are solely my own and not those of Carnegie Mellon University School of CS. ------------------------------------------------------------ From ycampbell@unam.mx Tue Sep 26 07:50:56 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!unam!ycampbell From: ycampbell@unam.mx (Yuki Campbell) Newsgroups: comp.sys.m68k Subject: Re: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Sep26.075056.2443@unam.mx> Date: Tue, 26 Sep 1995 07:50:56 GMT References: <1995Sep26.000456.5438@cmu.edu> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Sep26.000456.5438@cmu.edu>, isantos@cmu.edu (Ines Santos) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window. -- Yuki Campbell Practical Peripherals 14.4 @ 33,600 bps "When every node is whole, the channel opens." From jgarcia@pacbell.net Wed Sep 27 22:36:56 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!pacbell!jgarcia From: jgarcia@pacbell.net (Ji-woo García) Newsgroups: comp.sys.m68k Subject: Re: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Sep27.223656.4028@pacbell.net> Date: Wed, 27 Sep 1995 22:36:56 GMT References: <1995Sep26.000456.5438@cmu.edu> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Sep26.000456.5438@cmu.edu>, isantos@cmu.edu (Ines Santos) 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. -- Ji-woo García | jgarcia@pacbell.net PGP Key fingerprint: 5F7F EDFC DE45 7B8D "Keep the channels open." From bkuznetsov@utexas.edu Thu Sep 28 14:16:56 1995 Path: ashpoly!cascade!transat!ukc!fennimore!utexas!bkuznetsov From: bkuznetsov@utexas.edu (Bastien Kuznetsov) Newsgroups: comp.sys.m68k Subject: Re: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Sep28.141656.2556@utexas.edu> Date: Thu, 28 Sep 1995 14:16:56 GMT References: <1995Sep26.000456.5438@cmu.edu> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1995Sep26.000456.5438@cmu.edu>, isantos@cmu.edu (Ines Santos) writes: > Amiga audio hackers: you can demodulate the 14.2 Hz carrier in real time without bogging down the OS. Please make sure it's compatible with Kickstart 1.3 for those of us who haven't upgraded our A500s to 3.1 yet. Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Bastien Kuznetsov Practical Peripherals 14.4 @ 9600 Telebit bps "Tape doesn't lie at 02:14. Ears do."