Over these short distances, are you sure the phase shift would have that screech effect? With a wavelength of about 2.5 meters and assuming something like a 10nm overlap that would be 0.05 degrees (as I make it) out of shift. Would that have any kind of noticable affect?
I wasn't as much thinking about propogation delay (too many years since uni and forgot most of it
).
I was thinking more about the affect you get when two aircraft transmit at once on the same frequency, that screeching noise which I always assumed was due to inaccuraces between the two carrier frequencies causing a sub-harmonic which is in the auidable.
Perhaps I'm wrong (am only guessing at all this), but just can't see how it's any different...
SWANFIS - sorry to be a pain, but can you just clarify this - does the broadcast of an aircraft on one of the three frequencies get 're-broadcast' onto ALL the towers on ALL the frequencies, or just the towers on the OTHER frequencies (i.e. not the frequency the aircraft is tuned to)?