DME and VOR Quiz

What is the maximum distance between VOR and DME/TACANground installations if they are to have the same morse code identifier?

• 60 m

• 2000 m

• 600 m

• 300 m

A DME in tracking mode subsequently experiences a reduction in signal strength will switch the equipment in the first instance to:

• standby mode

• search mode

• memory mode

• signal controlled search

A DME that has difficulty obtaining a "lock-on": (NOTE: PRF = pulse recurrence frequency, PPS = pulses per second)

• alternates search mode with periods of memory mode lasting 10 seconds

• stays in search mode without a reduction in PRF

• stays in search mode but reduces PRF to max. 60 PPS after 100 seconds

• stays in search mode but reduces PRF to max. 60 PPS after 15000 pulse pairs have been transmitted

Of what use, if any, is a military TACAN station to civil aviation ?

• alternates search mode with periods of memory mode lasting 10 seconds

• stays in search mode without a reduction in PRF

• stays in search mode but reduces PRF to max. 60 PPS after 100 seconds

• stays in search mode but reduces PRF to max. 60 PPS after 15000 pulse pairs have been transmitted

DME channels utilise frequencies of approximately:

• 110 MHz

• 300 MHz

• 1000 MHz

• 600 MHz

A VOR and DME are co-located. You want to identify the DME by listening to the callsign. Having heard the same callsign 4 times in 30 seconds the:

• VOR and DME callsigns were the same and broadcast with the same pitch

• DME callsign was not transmitted, the distance information is sufficient proof of correct operation

• DME callsign is the one with the lower pitch that was broadcast several times

• DME callsign is the one with the higher pitch that was broadcast only once

In the DME system

• The aircraft equipment is called a transponder

• The receive and the transmit frequency is always split by 63 MHz

• The operation is similar to a primary radar system

• The channels are referred to as "X" channels paired with VORs and "Y" channels paired with ILS localizers

The reason for using different frequencies for transmitting and receiving in the DME system

• Is to avoid the reception in the aircraft of signals referring to other aircraft

• Is to prevent self-triggering of the receiving equipment by the transmitter

• Is to prevent overload of the system

• Is to permit more channels in the system

The airborne DME equipment will transmit pulse pairs at a comparatively high PRF

• At all times, except when the panel control "LO" is operated

• When the distance presented is above 50 NM

• Whenever a stable signal is being received from the selected ground station

• When first switched on and after a channel selection

In the DME system, responses in the aircraft equipment to answers to other aircraft is prevented

• By using a directional aerial in the aircraft

• By carefully selecting the correct channel

• By an irregular change in pulse-pair PRF in every aircraft installation, and by making the receiver sensitive for reception only in a short period of time of around the anticipated time of arrival of the answer from the ground station

• By using the "search mode" at frequent intervals