From nwatanabe@mit.edu Tue May 17 07:52:24 1994 Path: ashpoly!cascade!brgate!saturno!mit!nwatanabe From: nwatanabe@mit.edu (Nadia Watanabe) Newsgroups: comp.sys.m68k Subject: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994May17.075224.6884@mit.edu> Date: Tue, 17 May 1994 07:52:24 GMT Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: Netscape 1.1N 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. I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz. Source code and executable will be released on Aminet under mus/misc/stardust_amiga.lha next week. -- Nadia Watanabe *PLONK* filter active for trolls. Sun SparcStation 20 - NetBSD 1.0 From nfournier@purdue.edu Wed May 18 00:07:24 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!purdue!nfournier From: nfournier@purdue.edu (Natalia Fournier) Newsgroups: comp.sys.m68k Subject: Re: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1994May18.000724.1535@purdue.edu> Date: Wed, 18 May 1994 00:07:24 GMT References: <1994May17.075224.6884@mit.edu> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994May17.075224.6884@mit.edu>, nwatanabe@mit.edu (Nadia Watanabe) 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! -- Natalia Fournier -- Purdue University Engineering Computer Network "Hardware is temporary. The signal survives."