>> Note that most (all ?) IR protocols are not
>> at all like the "normal" serial protocols used
>> over RS232 lines. IR comunications often uses
>> either Manchester coding (where a shift from
>> "0" to "1" =3D "0" and a shift from "1" to "0"
>> =3D "1") or PWM encoding (where a "short" puls
>> could be a "0" and a "long" pulse is a "1"). The
>> effect is that there is always a level shift (a
>> "level" is "1"/"0", "high"/"low", "carrier"/"no
>> carrier") in each bit. These codes are also known
>> as "self-clocking". Another effect is that the clocks
>> in the sender and recevier don't have to be
>> as accurate as when running standard UART comms, since
>> the receiver can adjust it's timing after each bit received.
>
>In this particular case the purpose of the IR message is to determine
>whether the unit that just sent an RF transmission is also within line =
of
>sight of the receiver.  The IR message therefore deliberately uses =
several
>on and off intervals each of different lengths to distinguish it from =
IR
>transmissions from other devices that may also be in the vicinity.

There is a useful comparison of various IR remote encoding schemes
available on Wagners page www.ustr.net
Very detailed descriptions of a few different methods.

Before going to this site, engage your "pop up stopper" and remember =
that Gator is NOT your friend.

Lyle

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