From osuzuki@berkeley.edu Tue Oct 24 03:51:29 1995 Path: ashpoly!cascade!transat!ukc!fennimore!berkeley!osuzuki From: osuzuki@berkeley.edu (Olga Suzuki) Newsgroups: comp.sys.m68k Subject: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Oct24.035129.1202@berkeley.edu> Date: Tue, 24 Oct 1995 03:51:29 GMT Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: NewsWatcher 2.0b24 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. Long live the Amiga. Try doing real-time subcarrier demodulation on a 386 running Windows 3.1 without dropping frames! -- Olga Suzuki "In theory there is no difference between theory and practice." Amiga 3000T / SunOS 4.1.4 From hsouza@purdue.edu Tue Oct 24 22:28:29 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!purdue!hsouza From: hsouza@purdue.edu (Heather Souza) Newsgroups: comp.sys.m68k Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA Message-ID: <1995Oct24.222829.5336@purdue.edu> Date: Tue, 24 Oct 1995 22:28:29 GMT References: <1995Oct24.035129.1202@berkeley.edu> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Oct24.035129.1202@berkeley.edu>, osuzuki@berkeley.edu (Olga Suzuki) 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. -- Heather Souza Tape trading list upon request. SASE required for international mail.