HELP with Infrared emitter + sensor problems

oh, I guess I misunderstood something I read about having the IR emitter pulsed so the receiver can take it in.

" We write an Arduino sketch to make this LED flash 38,000 times per second so it can be detected by the PNA4602M. " I've read similar statements like this from different sources. It is flashed at 38 khz because that is what the receiver looks for, so it takes light with different frequencies out of the equation.... is this wrong or idk? haha. sounds right. maybe. Anyway that is why I am pulsing it.

This statement was taken from a powerpoint found online here.... web.cecs.pdx.edu/eas199/C/notes/1/1_IR_object_detection.ppt

please help. let me know if this is wrong and why, or visa versa