Part 2 VOR ADF Flashcards
VOR
Very High Frequency Omni Range
What is a VOR
A enroute, station-to-station Radio Navigation System
What does a VOR provide
magnetic Heading and Bearing information, Aircraft location around the VOR station
What does a VOR assist in providing
Position FIx
What can a VOR be co-located with
DME or TACAN ground stations
Radials are identifies by
0-360 degrees
VOR test station
non-rotating, very low power transmitter
VOR transmits what
FM and AM in phase
VOR modulation and how do they compare
30 HZ Fm reference signal
30 HZ AM variale signal
Compares the PHASE difference between the two signals
Components of a VOR system
Antenna Receiver Control Head Indication Interconnecting wiring and antenna coaxial cable
NAV receiver is located
in the radio rack or avionics bay
Frequency selector
mounted on the glare-shield
VOR can be displayed on
a variety of different instruments
Manual VOR indications are displayed on
CDI
HSI DOR deviation represents
5 degrees
Automatic VOR indications are displayed on
Compass Instruments
To/From indication
tells you what the aircraft would do , if you were to turn onto the selected course heading
VOR system operates in the
VHF frequency band from 108.0 - 117.95 MHz
NON LOCALIZER FREQUENCIES
A 30 HZ, FM “Sub carrier” is transmitted omnidirectional at
9960HZ + / - 480 HZ
The “sub carrier” is applied as
AM to the RF
The RF carrier wave is electronically rotated during transmission at a speed of
1800 RPM
The FM reference signal is synchronized with
Rotating directional (AM) signal
The FM Reference will always be at its positive peak when the directional (AM) signal is pointed
North VOR receivers will detect the AM signal’s positive peak, when the directional signal is pointed at the aircraft
ADF
Automatic Direction Finders
Purpose of ADF
Station to station Navigation
Radio navigation system
needle points towards ADF ground station
Ground stations are called non directional beacons
ADF frequencies
horizontally polarized 200-2000KHZ
ADF components
Receiver
Control Head
Indicator
Antennas used for ADF
Loop antenna (box) Sense Antenna (wire) Both may be combines into one unit
ANT
ANT mode parks at the 3 o’clock position The loop antenna is disables and all receiving is done through the sense antenna This mode provides the best audio reception
ADF mode
pointer is activated, wants to point to the station
BFO
Best frequency oscillator. generates audio tone when there is none
ADF loop
senses direction of radio station by seeking null position
2 Nulls degrees apart
180
what antenna gives you direction
loop and sense
Problems with ADF
coastal effect
night effect
quadrantal error
“P” static
Night effect
ADF uses a ground wave which follows the contour of the earth - Portion of the signal acts as a skywave - reflected off the ionosphere back to earth
Coastal effect - when the ground wave from the ADF transmitter reaches a coastline what happens
it will change direction slightly
“P” static interference
ADF is prone to noise interference
Quadrantal error
Electromagnetic fields around the 4 quadrants of the airframe can cause errors being introduced into the ADF system
How can quadrantal error be minimized
Quadrantal Error corrector
