>   
>  OK second issue that can be solve by the modulated signal is the receivers are being tripped by false singals from the other tx LED's.  If I was to modulate each transmitter with different frequency square wave, then each IR detector could feed to a PIC where it could measure the incoming frequency and know which device was being tripped.  
>  
>
Forget the PIC (or any other device you build yourself) for detecting  !!
check some datasheets e.g. TSOP1138 (they also explain why modulation is 
important)
  http://www.rentron.com/Files/TSOP7000.pdf
and see that this device can detect 4mW/m2 signal in ambient light of 10W/m2
Stef


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist