Tom Beecher wrote:
It's also relevant that the spectrum surrounding the 4.2-4.4 range has not
been an empty desert. It has been used for satellite downlink since the 60s
I think?
Yes, there are surely tons of differences in RF characteristics between the
two.
The important difference is in power. Downlink signal from satellites
is, at the ground, attenuated a lot. Moreover, downlink signal comes
from above an aircraft, though some are scattered by the ground to
the aircraft.
But let's be honest. Analysis would have been done decades ago on the
impact of spurious emissions from sat downlinks on RAs, so there should be
at least a baseline to work from.
Possible saturation of radar altimeter by 5G signal is caused
by signal power having nothing to do with spurious emission.
Either way this should not be a discussion now. This clearly was discussed
early in FCC filings, questions were asked, data was presented, and all
these parties signed off.
True. FCC even doubled guard band.
Masataka Ohta
