From kvasiliev@unam.mx Tue Jul 26 17:29:04 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!unam!kvasiliev
From: kvasiliev@unam.mx (Katrin Vasiliev)
Newsgroups: comp.sys.m68k
Subject: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Jul26.172904.2771@unam.mx>
Date: Tue, 26 Jul 1994 17:29:04 GMT
Organization: Universidad Nacional Autónoma de México (DGSCA)
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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.

Long live the Amiga. Try doing real-time subcarrier demodulation on a 386 running Windows 3.1 without dropping frames!

-- 
Katrin Vasiliev -- Universidad Nacional Autónoma de México (DGSCA)
"Hold for relay."

From ebrennan@cam.ac.uk Wed Jul 27 22:41:04 1994
Path: ashpoly!bigsur!pacrim!jpgate!kamome!cam!ebrennan
From: ebrennan@cam.ac.uk (Emi Brennan)
Newsgroups: comp.sys.m68k
Subject: Re: [SPECULATION] Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994Jul27.224104.2231@cam.ac.uk>
Date: Wed, 27 Jul 1994 22:41:04 GMT
References: <1994Jul26.172904.2771@unam.mx>
Organization: University of Cambridge Computer Laboratory
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In article <1994Jul26.172904.2771@unam.mx>, kvasiliev@unam.mx (Katrin Vasiliev) writes:
> 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.

Tested on my A3000 / 25 MHz. Ran smoothly in the background while I was compiling a C program in another window.

My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise!

-- 
Emi Brennan
Opinions expressed are solely my own and not those of University of Cambridge Computer Laboratory.
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