Newsgroups: comp.robotics
Path: brunix!uunet!cs.utexas.edu!zaphod.mps.ohio-state.edu!rpi!utcsri!torn!newshub.ccs.yorku.ca!newshub.ariel.yorku.ca!cs911225
From: cs911225@ariel.yorku.ca (KEN E WILLMOTT)
Subject: IR remote timing
Message-ID: <1992Dec21.165153.1282@newshub.ariel.yorku.ca>
Sender: news@newshub.ariel.yorku.ca (USENET News System)
Organization: York University, Toronto, Canada
Date: Mon, 21 Dec 1992 16:51:53 GMT
Lines: 43

Hi,
I found the postings about the Sony infrared remote control
protocol interesting, but I was alarmed to note that it did
not seem to mesh with the readings I got from 3 different
controls in use in my living room. These are an RCA t.v.,
an Onkyo receiver, and a Jerrold tuner.

Here is what I found (presence of signal = logic 1):

First, there is an AGC stabilization pulse, followed by a short
break. Then come the mysterious bit patterns (I'll get to them).

Signal			Duration	Polarity
------			--------	________

AGC pulse		18.5 ms		1
pause			850 us		0
50 3-bit patterns	1125 us		(see below)

Each 3-bit patterns consists of three 375 us. long bits.
The first two are always the same, and convey the binary
information. The last is always set to 0.

When these bits are laid out end to end, they look like
the following (actual data from one of my controllers):

11 01 11 01 10 10 10 11
01 01 10 10 11 10 10 10
10 11 11 01 11 11 01 01
01

There are two interesting features of this stream, neither
of which I am sure is always true, or merely an artifact
of the particular button I chose.

1) The pattern 00 never appears
2) The pattern 10 never precedes the pattern 01

If anybody out there has more information to add to this,
I would be eternally grateful.

	-Ken

