Re: Simple RF/IR distribution

[Nigel Orr <nigel.orr@xxxxxxx>]

At 11:39 01/03/00 -0000, you wrote:
>> If you did this in the analoge domain, it would work for any type
of IR.
>
>Any circuits please...?  Open to all suggestions (except CAT5 - I'm not
>doing that in this house, next one..... probably)

I'm not sure what is being suggested, but I'll try to explain the usual
system.  An IR receiver usually consists of a tuned circuit, set between 36
and 40kHz, with a _lot_ of AGC (gain control) and filtering to get rid of
extraneous noise.  The output of the tuned circuit is a digital pulse
train.  Typically if you use a receiver in the 38-40kHz range, it will
decode every IR remote's codes, with probably a slightly reduced range (but
still enough for domestic use) at the frequency extremes.

The digital control signal is then used to trigger an oscillator at
36-40kHz to drive an IR LED.  Again, frequency isn't too critical unless
you need long ranges.

The digital signal can be transmitted any way you want- down the phone
line, over cat-5, over an RF link, some other wired modulation scheme, you
could even use X10 if you weren't in a hurry!

What you don't want is to receive and repeat all the noise that is received
by an IR-sensitive photodiode- just the desired signal.

Now, which analogue domain did you have in mind? :-)

Nigel


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