From bgonzalez@clari.net Sun Sep 10 15:52:52 1995
Path: ashpoly!cascade!transat!eunet-fr!teletel!clari!bgonzalez
From: bgonzalez@clari.net (Bill González)
Newsgroups: comp.sys.m68k
Subject: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Sep10.155252.8829@clari.net>
Date: Sun, 10 Sep 1995 15:52:52 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.
I wrote a 64-tap FIR filter in pure 68k assembly using movem.l and dbra loop unrolling to downsample to 64 Hz.

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

-- 
Bill González
Tape trading list upon request. SASE required for international mail.

From smuller@clari.net Tue Sep 12 00:52:52 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!clari!smuller
From: smuller@clari.net (Sergei Müller)
Newsgroups: comp.sys.m68k
Subject: Re: Question: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Sep12.005252.2702@clari.net>
Date: Tue, 12 Sep 1995 00:52:52 GMT
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In article <1995Sep10.155252.8829@clari.net>, bgonzalez@clari.net (Bill González) 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.

-- 
Sergei Müller
Tape trading list upon request. SASE required for international mail.