[Patrik]

Dean or Woody mentioned at kickoff that it was hard to get the light beam in such a way that you could read light output from another sensor (in that case he was referring to jammers).
I think these are IR sensors/emitters ( I didn't notice a strong enough output of visible light on the device to be for detecting). So as long as no one is pointing IR emitters at the field ambient light shouldn't be a problem. All the fields I have been on are well shaded except for maybe main field at nationals last year, but even then I'd have problems believing there'd a be a problem with ambient light. Of course I haven't worked with these sensors except for fooling around with them this year and skimming the specs so I dunno.