Xref: utzoo comp.sys.handhelds:3128 sci.electronics:15061
Path: utzoo!attcan!uunet!munnari.oz.au!uniwa!earwax.pd.uwa.oz.au!andrew
From: andrew@earwax.pd.uwa.oz.au (Andrew Williams)
Newsgroups: comp.sys.handhelds,sci.electronics
Subject: Infra-red data for HP28S wanted
Summary: Does anyone know the modulation frequencies of the infra-red output?
Keywords: Infra-red,modulation,frequency
Message-ID: <andrew.656252611@earwax.pd.uwa.oz.au>
Date: 18 Oct 90 12:23:31 GMT
Sender: usenet@uniwa.uwa.oz (USENET News System)
Organization: University of Western Australia
Lines: 12

Hi- I'm trying to build a receiver for the infra-red printer output on my
HP28S. The data seems to be RS232 protocol, but getting the frequency
right is a bit tricky. I assume thats its a carrier of around 40kHz, with
a couple of signal tones for 1 and 0 around a few hundred Hertz. Does
anyone out there know the exact frequencies, for both carrier and signal?
(I dont have a storage CRO, and its pretty tricky triggering properly
without one). With a bit of luck, I'll be able to make a 'Infra-red to
RS232' converter, and keep up with the 48 owners (at least partially)!
			Andrew Williams,
			Physics Department,
			University of Western Australia.
			(andrew@earwax.uwa.oz.au)