If you're trying to detect which of the receivers has responded first, you can't use pulseIn() because this will only wait for a response on one input at a time. I suggest you follow the interrupt based approach I outlined earlier.
If you're trying to detect which of the receivers has responded first, you can't use pulseIn() because this will only wait for a response on one input at a time. I suggest you follow the interrupt based approach I outlined earlier.