Automatic Direction Finder (ADF) Flashcards
What does ADF stand for?
Automatic Direction Finder
What is a NDB?
Non Directional Beacon
A ground station that transmits a non directional signal on a specific frequency
Where does ADF operate?
in the low to medium frequency bands
Which direction does the ADF indicator point?
only points to the station direction NOT the direction the aircraft is necessarily flying in
The entire ADF system in the aircraft consists of:
A receiver, a control head, an indicator, and two antennas (a loop antenna and a sense antenna)
What is a Beat Frequency Oscillator (BFO)?
causes a tone to be heard on the radio output when a station is received
Why do ADFs have a BFO?
so that stations can be identified while only broadcasting a carrier wave
ADF data can also be displayed on what?
an RMI indicator
What circumstances can you test the ADF?
outside of the hangar and should best tested with the engine running
What will the technician need to know in order to test the ADF:
the bearing to the local station and its frequency
The ADF indicator can be found in two forms:
Fixed card
and
Movable card
With a movable card it is best to align the compass direction with what?
The magnetic compass
How is the loop antenna polarized?
Horizontally
What is the antenna designed to receive?
The H - field being broadcast from the NDB
What is the purpose of the loop antenna?
To narrow the direction to two possible directions
