HF radio question

[Lberto]

SSB

QUOTE
Those squeals are known as heterodynes or beats, and can still occur on SSB, because they happen when the carrier frequencies are close but not exactly the same. Agreed, they are less than on AM, but FM should reduce the squealing considerably.
UNQUOTE

As Ham Radio Op ,and aviation enthusiast let me inform that SSB has NO carrier (it is indeed suppressed) and aircrafts use the USB (Upper Side Band).
At a certain location you may hear different stations on the same freq.,and if the signals are similar in level you'll hear both of them clearly, but rarely two stations will try to contact the same ground station at the same time , there are procedures and Selcals in place to avoid that,at least for commercial aviation.