Two nearby ASOS broadcasts on the same frequency: Why no squeal?

"Peter R." wrote in message
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In any case, I am curious how it is possible for two transmissions to be
heard over an aviation frequency without the squeal (I forgot the
appropriate technical term for this).



The "squeal" that you refer to, is the absolute difference in frequency
between the two base carriers of the two different transmitters. This
"difference" is known as the "beat" frequency. If the two base-carrier
frequencies are exactly correct, then the difference would be zero and no
"beat" sound would be produced. Today's equipment... it is normal to
maintain transmitter frequencies very, very accurate.

The human ear does not hear very well below about 20 hertz, so a tiny
difference of 5 or 10 hertz would not produce any "sound", either...
although it may manifest itself as a quick "pulsing" in the volume of the
signals as your receiver attempts to handle the interfering signals.