DME

Question 1

What does DME use to calculate range

Answer 1

Secondary radar

Question 2

What happens with the DME during:
1-search mode
2-memory mode
3-auto stby

Answer 2

1-transmitter transmits 150 pulses per second for 100 seconds, if no station found transmitter drops rate to 60 pulses per second, then goes to auto stby waiting for station to get into range,
If station found DME calculates range
2-DME signal lost, memory mode valid for 10s, during which it continues to show distance, after 10s, goes into search mode
3-doesnt transmit, ground station transmits filler pulses to switch DME out of stby

Question 3

At what distance do colocated VOR and DME have to be in order to have the same ident

Answer 3

Within 2000ft

Question 4

At what frequency does DME operate

Answer 4

UHF at 960MHz - 1215MHz

Question 5

What is the max error allowed for DME

Answer 5

0.25nm +1.25% slant range

Question 6

What PRF does DME operate at

Answer 6

2700 pps

Question 7

What frequency does a DME station respond at

Answer 7

63MHz above/below interrogation frequency

Question 8

What does using a random PRF with a DME do

Answer 8

Allows it to distinguish between its own replies and replies sent from other a/c

Question 9

What is the function of the Echo Protection Unit within a DME

Answer 9

It protects the interrogation-receiver from tracking reflected pulse pairs by detecting if it has been locked on by reflected pulse pairs

Question 10

What is the function of the Echo Protection Unit within a DME

Answer 10

It protects the interrogation-receiver from tracking reflected pulse pairs by detecting if it has been locked on by reflected pulse pairs