Re: Whole House IR.

[Keith Doxey <keith.doxey@xxxxxxx>]

Hi Stuart,

The units I have designed can be used either as a passive system just
repeating received signals via the transmitters as in your first example,
or can be used to feed a PC or Homevision etc for some intelligent
processing before sending IR to the required transmitter.

You are right to be cautious about the PC picking up the signals it has
just sent as this could cause absolute chaos, however this is more of a
problem with the passive system which blindly repeats whatever it picks up.
Whilst nothing is happening the system would be totally idle until someone
somewhere fired a remote control. When this happens ALL the transmitters
would repeat it into every room. At this point EVERY receiver would pick up
IR and try to send it to all transmitters. At best you would get severe
errors in the transmissions and at worst the system would lock up with all
transmitters permanently on until the IR leds burnt out :-((

If you are going to have a combined receiver/transmitter you need to
incorporate something that will disable the receiver for the duration of
the IR transmission.

MY personal preference is for localised IR mini emitters attached to the
device to be controlled. This totally avoids the possibility of IR lockup
by not filling the room with IR. It also allows easy zoned control which is
very useful if you have several devices that respond to the same signals. I
have 4 satellite receivers that use the same codes but for different
functions.

Hope that helps

Keith


-----Original Message-----
From:	Grimshaw Stuart [SMTP:stuart.grimshaw@xxxxxxx]
Sent:	19 October 1999 09:28
To:	'UKHA List (E-mail)'
Subject:	[ukha_d] Whole House IR.

This seems to be a recurring topic on the list, but this question should
be my last on the subject :)

There are two ways I can think of for acheiving this, I'd appreciate
anyone elses thoughts & experiences of either...

The two systems have an IR transeiver in every room, it's the gubbins
behind it that differs.

1) Have a repeater in a "central" location that just repeats any
infra
red signal it finds back out over the rest of the transceivers in the
house. With a device such as a Red Rat, or Actisys IR210L atatched to
the PC to receive any signals, and transmit any responses back into the
system.

2) Have the PC act as a "hub" for the IR, and have it decide
which needs
to be transmitted back into the system, and which it needs to respond
to...

The first seems the more simple of the two ideas, but also the more
limited. Also, transmitting the signal around the house in wires would
seem to be a problem what with signal loss and interferance. I've seen
the panels Mark and Keith designed, and I presume they work OK, so it
isn't an insurmountable problem, Mark's house will have far longer cable
runs than mine :)

The second option would give me far greater control over the system, but
would still require the transeivers in every room. Might there also be a
problem with the PC receiving the signals it has just sent?

I'd appreciate your thoughts and experiences with this kind of thing.

Also, I'll be compiling any answers and adding them to my beginners FAQ,
http://www.stubbynet.org.uk/homeautomation/myquestions.htm

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