You guys are great! 
Thanks!
Paul__B, The other thread was basically another question, so this is why I started this thread.
I have a lot to think about, thanks. I don't want to let the Arduino produce the pulse, because it also has to deal with several interrupts. With every interrupt there will be some calculations, and I'm afraid this will mess up the pulse, making it useless for the receiver. And since the moment of transmission is relevant, I do not want to have it sent multiple times.
Or is this no problem after all? Of course, I wont use any delay()s.
Thanks a lot!