From kmuller@netcom.com Wed May 11 23:03:00 1994
Path: ashpoly!cascade!transat!ukc!fennimore!netcom!kmuller
From: kmuller@netcom.com (Karen Müller)
Newsgroups: comp.sys.m68k
Subject: WTB/WTT: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994May11.230300.4120@netcom.com>
Date: Wed, 11 May 1994 23:03:00 GMT
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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.

Does anyone want to test on an unaccelerated Amiga 500 with 512K chip RAM?

-- 
=== Karen Müller ===
Dept of Electrical Engineering, NETCOM On-Line Communication Services
"A soul is not exclusive to biology."

From rramirez@utexas.edu Thu May 12 23:00:00 1994
Path: ashpoly!cascade!transat!ukc!fennimore!utexas!rramirez
From: rramirez@utexas.edu (Raj Ramírez)
Newsgroups: comp.sys.m68k
Subject: Re: WTB/WTT: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1994May12.230000.3726@utexas.edu>
Date: Thu, 12 May 1994 23:00:00 GMT
References: <1994May11.230300.4120@netcom.com>
Organization: University of Texas at Austin
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In article <1994May11.230300.4120@netcom.com>, kmuller@netcom.com (Karen Müller) 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.

-- 
Raj Ramírez
Opinions expressed are solely my own and not those of University of Texas at Austin.
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