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

"Ron Parsons" wrote in message
...
In article ,
"Peter R." wrote:

For some reason known only to the FAA, both Dunkirk, NY (KDKK), and
Wellsville, NY (KELZ), two small, uncontrolled airports in southwestern
NY
state that are about 60 nm apart, share the same ASOS frequency.

For pilots flying to Dunkirk from the east, retrieving the current ASOS
broadcast is not possible until about 25nm east of the airport, due to
the
more powerful KELZ broadcast. This is not so much a problem when
conditions are VFR, but when they are IFR I prefer to retrieve the ASOS
as
early as possible in order to choose and prepare for a particular
instrument approach.

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).

It's not unusual for a chain of transmitters to broadcast on what
appears to be the same frequency. They are actually all set about 5khz
apart and aviation radios filter out the squeal. That filter also makes
it more difficult to hear the higher pitched female voice.

Guess every aviation radio I have ever used was broken 'cause they all
squeal. I think you need to review basic radio theory as it applies to our
dear old AM aviation radios.