Principles Of ADF Flashcards
What is the primary functions of the ADF?
Indicates the tuned station’s relative or magnetic bearing
How does an aircraft’s ADF equipment display the direction of a ground transmitter?
Needle always points to the tuned station / relative bearing
What replaces the relative bearing indicator RBI in modern ADF systems?
Radio Magnetic Indicator, shows both relative and magnetic bearings plus heading.
What frequency range do ADF ground transmitters operate in, what are they called?
190 kHz ~ 2000kHz, they are known as Non directional Beacons NDBs
What is a key drawback of using commercial broadcast stations in ADF?
They identify only every half hour, making location determination hard.
Which Frequency Range is primarily used for navigation, and what special frequency is noted?
190~550 kHz, 500kHz is an international distress frequency.
How do ADF transmitters radiate and indemnify their signals?
They emit a vertically polarized field and use Morse code (CW or 1020 Hz MCW) for identification.
What are alternative name was historically used for the ADF?
The radio compass
What happens to the ADF needle when the aircraft turns?
It continually realigns to point toward the tuned station.
How do navigation stations differ from commercial broadcast stations in the ADF frequency range?
Navigation stations (190 ~ 550 kHz) are designed for navigation, while broadcast stations (550 kHz ~ 1,6 MHz) update identification only every half hour.
How are ADF signal identifications transmitted from the NDB?
Via Morse Code (CW) or a 1020 Hz modulated CW (MCW) signal.
What key information does the RMI provide over the traditional RBI?
It shows both relative and magnetic bearings, plus the aircraft’s heading.
What is the role of the omni-directional sense antenna in ADF?
Provides reference signal to resolve the loop antenna’s dual null ambiguity.
What issue arises in the ADF system without the omni-directional sense antenna?
Two nulls would occur, causing ambiguous indication
How is the ADF system unique regarding antenna usage?
Uses two antennas to receive the same signal.
