DME Flashcards
DME measures the difference between __ pulses being sent from an aircraft and received back, on different frequencies
paired
The aircraft is the first to transmit on _HF, when the DME transponder on the ground returns the signal after a __ microsecond delay.
UHF 50
The 50 microsecond delay exists to reduce the chances of uncoordinated activity when the interrogating aircraft is ___ the station
near
If the DME is part of an ILS installation, the delay is (not) present
not
The pulses are . miliseconds wide
3.5
___ frequencies are used, otherwise the first pulse received would be the ground return from below.
Two
___, the deliberate random variation of the time interval between interrogations, is used to identify pulses
Jittering
Only signals with the same jittering pattern, which is the ___, are replied to.
PRF
DME is _HF based, between __ and ___ _Hz
960 1215 MHz
___ pulse pairs are those which the beacon transmits even without interrogation
Squitter
Signal discrimination depends on the ___ ___ and ___ spacing.
frequency separation, pulse
The DME ident is pitched ___er than that of a VOR, at ___ _z
higher 1350 Hz
The groundspeed readout ___ at an increasing rate when overflying an overhead the beacon
reduces
The slant range is calculated by ___, remembering to subtract the __ delay at the transponder
Time / 12.4, 50
Normally, __ pulse pairs are transmitted per second, going up to ___ for searching
30 150
Up to ___ aircraft can interrogate the system before beacon saturation occurs.
100
The ground station can only cope with ___ pps
2700
DME wavelengths are ___
decimetric
The design requirements for DME-P stipulates that the total system error should not exceed . NM
0.2
If an interruption is caused, the airborne equipment is switched to memory mode for about __ seconds, with no signal received after that, the ___ flag appears
10 off
The ___ ____ ____ circuit creates a __ microsecond delay on the transponder in order to allow enough time after the receipt of the interrogation pulse for any other reflected multipath echoes to arrive at the station and be ignored
Echo Protection Circuit
DME airborne interrogation is made on one of ___ channels, at _ _Hz spacing between ___ and ___ _Hz
126 1 MHz 1025 and 1150 MHz
UHF propagation methods are ___ or ___ waves
direct space
The interrogation by the DME receiver does not start before ___ ___ of the tuned DME station are received
pulse pairs
