From mokonkwo@u-tokyo.ac.jp Fri Oct 13 16:31:10 1995
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!u-tokyo!mokonkwo
From: mokonkwo@u-tokyo.ac.jp (Morag Okonkwo)
Newsgroups: comp.sys.m68k
Subject: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Oct13.163110.2892@u-tokyo.ac.jp>
Date: Fri, 13 Oct 1995 16:31:10 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?

-- 
Morag Okonkwo
Tape trading list upon request. SASE required for international mail.

From jsilva@ox.ac.uk Sun Oct 15 11:17:10 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!ox!jsilva
From: jsilva@ox.ac.uk (Joachim Silva)
Newsgroups: comp.sys.m68k
Subject: Re: Data: Real-time 14.2 Hz demodulation on Amiga Paula audio DMA
Message-ID: <1995Oct15.111710.7316@ox.ac.uk>
Date: Sun, 15 Oct 1995 11:17:10 GMT
References: <1995Oct13.163110.2892@u-tokyo.ac.jp>
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In article <1995Oct13.163110.2892@u-tokyo.ac.jp>, mokonkwo@u-tokyo.ac.jp (Morag Okonkwo) 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!

-- 
Joachim Silva
Tape trading list upon request. SASE required for international mail.