IREX 2.0 Flashcards
What sort of lines do VHF waves travel as?
Straight lines
Where do VHF waves send most of their energy and what are they referred to as?
Through the sky.
Sky waves
Where do VLF waves send most of their energy and what are they referred to as?
Into the ground which follows earths curvature.
Ground waves
What does the NDB send out?
Ground waves that follow the earths curvature at equal strength in all directions
What is the airborne equipment which receives the NDB?
ADF (Automatic direction finder)
What frequency does NDB operate in?
Low to medium range (200-400)
What conditions does NDB ground waves work best/worst over?
Best over water
Worst over dry sandy country
Is the rated coverage of an NDB affected by the height at which the aircraft is flying?
NO!
What are some limitations that apply to the NDB?
Night effect Co-channel interference Thunderstorm effect Mountain effect Coastal refraction Quadrant error
How does night effect affect the NDB?
Skywave reflected from ionosphere, it causes interference with the ground wave mainly at night.
Receives the ground wave fine but the sky wave later, causing them to be out of phase
Results in reduced rated coverage
How does co-channel interference affect the NDB?
Other transmitters transmitting on same frequency
How does thunderstorm effect affect the NDB?
Radio signals from thunderstorms affect the net signal received by the ADF
How does mountain effect affect the NDB?
Caused by reflections of the NDB signal from mountains. This error decreases with increased height
How does coastal refraction affect the NDB?
If ground wave crosses the coast at an angle, in bends towards the coast line
How does quadrant error affect the NDB?
Interference caused by structure of the aircraft
Once the NDB signal has been received, what does the ADF do and how does it present it to the pilot?
Points TO the station.
Presented to the pilot as a position on a fixed card
Does the fixed card on an NDB move as aircraft heading moves?
No, remains fixed with zero always representing the aircraft’s nose, 180 the tail, 90 right wing, 270 left wing
If a pilot flies towards an NDB by adjusting the heading so point of ADF needle is on zero, where will the resulting track take you?
TO the station
On a constant heading, what is the deflection of the point or tail of the needle from 0 or 180 called?
Drift
What is the drift?
Angular difference between heading held and the track that is resulted
How do you work out the track error for NDBs?
Flight path - track
