2a Doppler Flashcards
Transmitted energy undergoes a perceived shift and frequency as the distance between the transmitting source in the observer changes due to relative motion
Theory of Doppler
This occurs when transmitter OR receiver are in motion
Single Doppler shift
This occurs when BOTH transmitter and receiver are in motion
Double Doppler shift
This calculates ground speed and drift angle it uses unmodulated continuous wave
The basis for aircraft Doppler systems
The antenna beam configuration consists of 4 beams. 2 forward beams that are positive shift and 2 rear beams that have
Negative shift
Headwind or tail wind will increase or decrease what
Ground speed
Cross winds affect what
Drift angle
If the ground speed increases, the forward and rear beams will do what?
Both increase
If ground speed decreases forward beams and rear beams will do what
Decrease
The drift angle affect.
If there is right drift, the forward right beam will increase positive shift while the forward left beam decreases positive shift. What will both rear beams do?
Rear right beam will become less negative.
Rear left beam will become even more negative
Vice versa for left drift
The APN-218 Doppler navigation system has 2 LRUs. The ground speed drift indicator and what? 
Doppler Velocity Sensor DVS
The APN-218 Doppler Nav System “locks on” at 96 knots. It has a max altitude of how many feet?
70,000
The pitch and roll limitations for the Doppler navigation system is what
Pitch = +/- 25°
Roll = +/- 40° 
This LRU controls DVS functions and displays current ground speed and drift angle
Ground speed drift indicator GSDI
This LRU contains the R/T, The antenna, all DVS related computational circuitry and a dehydrator
Doppler velocity sensor
