Why does the FAA still use AM? Our aviation industry depends on AM to keep
our people safe and we have the best safety record in the world. AM should
be eliminated as some would say ? HUMM.
Because of the capture effect of FM. They don't want a strong signal from
one aircraft to completely block a slightly weaker signal from another.
With AM, despite the QRM, both signals would be heard at the same time,
letting air traffic controllers know there was a second plane. With SSB,
there is too much liklihood one station may be too far off frequency to be
audible at a critical moment.
I have also heard it said that the doppler shift from a jet aircraft running
at full speed is enough to make SSB inaudible due to frequency error. Not
sure if this it true. Anyone know from experience?
Don k4kyv
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