Electronic navigation that in use
today . This VHF Omni-Range
navigation method relies on the
ground based transmitters which
emitted signals to VOR receiver. The VOR system operates in the VHF
frequency band , from 108.0 to
117.95 MHz. The reception of VHF
signals is a line of sight situation . You
must be on the minimum altitude of
1000 feet (AGL) above ground level in order to pick up an Omni signals
service range.
OPERATION
The VOR facility at ground base
transmits two signals at the same time.
One signal is constant in all directions
as a reference phase. Another signal, it
is variable-phase signal and it rotates
through 360 degrees, like the beam from the lighthouse. Both signals are
in phase when the variable signal
passes 360 degrees (reference to
magnetic north) and they are 180
degrees out of phase when the
rotating signal passes 180 degrees The aircraft equipment receives both
signals. The receiver will calculate the
difference between the two signals,
and interprets the result as a radial
from the station to pilots on the
aircraft.
RADIALS: The two signals from VOR
transmitter generate 360 lines like
spokes in a wheel . Each line is called a Radial . VOR navigation equipment on the airplane will determine which of
those 360 radials the airplane is on.
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