AN/APN Doppler

Question 1

Doppler components

Answer 1

• Receiver/Transmitter and Antenna (under fuselage)
• Signal Data Converter (SDC)
  o Determines Doppler shift of received signals
  o Convert data into drift angle and ground speed
  o Conducts signal to noise checks
  o Performs system validity checks and sends status signal to ATS
• Emulated Control Display Unit (CDU)
  o Graphical Drift display
  o G/S & Drift Digital Readout
• Air Training System Computer (ATSC)
  o ATSC generates the software for the emulated Control Display Unit (CDU)

Question 2

Doppler inputs/outputs

Answer 2

Inputs
-	Antenna
-	Receiver, sends frequency to SDC
-	SDC sends it to ATSC
Outputs
-	ATSC sends it to CDU
-	Drift and G/S displayed in Data Information Display

Question 3

Doppler limits

Answer 3

• Drift 20 degrees maximum

- Ground speed: 25 to 650 kts (666 kts during self test)