DME part 2

Question 1

DME (emission code P0N) is a secondary radar system operating between ? and ? MHz
in the ? band at 1 MHz spacing; this provides 252 spot frequencies or channels

Answer 1

DME (emission code P0N) is a secondary radar system operating between 960 and 1215 MHz
in the UHF band at 1 MHz spacing; this provides 252 spot frequencies or channels

Question 2

s. A modern DME is inherently accurate to +/-

Answer 2

0.2 NM

Question 3

The aircraft’s interrogator transmits a stream of omni-directional pulses on the carrier frequency
of the ground transponder. Simultaneously the interrogator’s receiver starts a Range Search.
At the transponder on the ground the received interrogation pulses are re-transmitted, after a
delay of 50 µs, at a frequency that is +/- ? MHz removed from the interrogation frequency

Answer 3

The aircraft’s interrogator transmits a stream of omni-directional pulses on the carrier frequency
of the ground transponder. Simultaneously the interrogator’s receiver starts a Range Search.
At the transponder on the ground the received interrogation pulses are re-transmitted, after a
delay of 50 µs, at a frequency that is +/- 63 MHz removed from the interrogation frequency

Question 4

· The DME operates in the UHF band reply frequency.

· The transponder reply carrier frequency differs by 63 MHZ from that of the interrogation signal. This stops it from receiving ground reflected signals.

· The DME indicates the slant range, i.e. a combination of the ground distance and the height of the aircraft above the station. It won’t indicate 0.0 NM, except on rare occasions.

· The principle of operation for the DME system is time.

Answer 4

· The DME operates in the UHF band reply frequency.

· The transponder reply carrier frequency differs by 63 MHZ from that of the interrogation signal. This stops it from receiving ground reflected signals.

· The DME indicates the slant range, i.e. a combination of the ground distance and the height of the aircraft above the station. It won’t indicate 0.0 NM, except on rare occasions.

· The principle of operation for the DME system is time.