Not quite.

There is a subcarrier modulation on the main carrier that is 9960 Hz. amplitude
modulated onto the main carrier. The subcarrier is FM modulated with a 30 Hz.
reference signal. The subcarrier is transmitted equally in all directions.

The carrier is also transmitted by a series of antennas spaced around the
station. These antennas are fed by a mechanism rotating at 30 Hz. and
phaselocked to the subcarrier reference. The rotating antenna is calibrated so
that the rotating signal and the reference signal are perfectly in phase at due
north of the station. As you rotate around the station, the phase between the
rotated (variable) and constant (reference) signal changes degree of phase for
degree of rotation.

(There is another way of doing it, far more technically difficult to explain.)


Jim


(Teacherjh)
shared these priceless pearls of wisdom:

-
-The VOR signal out of the receiver is a 9960Hz sine wave that is AM
-modulated at 30Hz and FM modulated at 30Hz. The phase difference
-between the AM and FM signals is the bearing to the station.
-
-
-How does that work. =Something= has to be directional, no?
-
-Jose

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com