"Frank's" wrote in message
news:YJhdh.17283$YV4.16290@edtnps89...
wrote in message
ups.com...
It is possible to get nonlinear interactions among electromagnetic
waves in plasmas, but you generally need very large amplitudes to get
nonlinearities to kick in.

I'm guessing that "space modulation" has something to do with multipath
reflections or something; the VOR signal that rotates is going to be
modulated by the buildings, mountains, and so forth around the
transmitter, generally, the "space"

Just a guess; I don't really know anything about VOR.

Dan

Space modulation, in the case of VOR, is produced by a dipole
rotating at 1800 rpm. The rotating dipole pattern produces a
30 Hz amplitude modulation of the VOR omni-directional
pattern. This rotating pattern provides bearing information
to the receiver. The reference 30 Hz is provided by
FM modulation of the omni-directional pattern.

73,

Frank (VE6CB)


Thanks Frank, I thought the FM modulation was caused by doppler shift as a
result of the antenna rotation