Distance measuring equipment
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Distance Measuring Equipment
A DME is a transponder-based radio navigation technology that measures distance by timing the propagation delay of VHF or UHF radio signals. [[1]]
- A radio pulse takes around 12.36 microseconds to travel 1 nautical mile (1,852 m) to and from; this is also referred to as a radar-mile.
- The aircraft interrogates the ground transponder with a series of pulse-pairs (interrogations) and, after a precise time delay (typically 50 microseconds), the ground station replies with an identical sequence of reply pulse-pairs.