VORs Flashcards
VHF Frequency Range
108 MHz to 117.95MHz
Conventional VOR
Reference phase is FM
Variable phase is AM
Clockwise movement
Strongest when ac directly pointing at beacon
Rotating antenna 30 times per second
Doppler VOR
Reference phase AM
Variable phase FM
Anti-clockwise
Uses electronic sweeping
Principles of operation of a VOR
Bearing by phase comparison
Two signal phases
90 degrees - east
180 degrees - south
Etc
Doppler advantages of a conventional VOR
More accurate
Less susceptible to siting errors
VOR frequency band
112.000MHz to 117.95MHz
Think odd numbers at the end
ILS Frequency Band
108.10MHz to 111.95MHz
Odd numbers below VORs 112.000MHZ
Terminal VOR frequency band
108MHz to 111.80MHz
Even numbers below VOR - odd numbers in same range are ILS
50KHz separation
Flight accuracy for a VOR
Must be kept within half of full scale deflection of required track
VOR ground monitoring system - limits and operation
Keep within 1 degree accuracy/loss of strength signal 15%
Remove ident/nav components or shut down transmitter
VOR errors
Bending - building etc/documented
Scalloping - building/vehicles/refraction - slow oscillation of bearing
Cone of confusion - 35 degrees either side vertically
Scalloping
Due to reflection radials bent leading to fluctuating indications
VOR oscillates
Must be less than +- 2 degrees
Cone of confusion
No single vertically above
Cannot be no less than 40 degrees above the plane of the VOR
Tan (40) x height nm x 2
VOR are identified by
3 letter Morse code and or plain voice communications
ATIS and VORs…
ATIS info is often transmitted on VOR frequency’s
Doppler VOR Range
200NM - en route IFR traffic
VOR/DME is a
Rho - theta
Intercepting a radial flight director provides
Optimum bank angle to reach radial
DME interrogator uses irregular transmission sequence because
Able to distinguish between his own reply pulse pairs and the reply pulse pairs of the other aircraft
Jittery Frequency
TVOR
A VOR station with a shorter range used as part of the approach and departure structure of aerodrome
DME receiver can distinguish between other aircraft’s due to
Unique pulse pairs
DME receiver can distinguish between itself and the reply because
Frequency transmitted +- 63MHz
TVOR Frequency Band
108MHz to 111.80MHz
AC on different radials at equal distance from a VOR - Reference vs Variable Signal
Equal reference signal (same DME distance around VOR)
Unequal variable signals (different radials as antenna moves)
A radial is
A magnetic bearing outbound from a station called the QDR.
Travel the shortest routes around earth (great circles)
Total system error using a VOR
5%
