ABSTRACT
The DME navigation aid contains a transponder
(receiver and transmitter) contained within a
single navigation aid, Figure 11.2(b). The aircraft
equipment radiates energy pulses to the DME
navigation aid; secondary signals are then
transmitted back to the aircraft. An on-board
interrogator measures the time taken for the
signals to be transmitted and received at the
aircraft. Since we know the speed of radio wave
propagation, the interrogator can calculate the
distance to the DME navigation aid. DME
navigation aids can either be self-contained
ground stations, or co-located with a VOR
navigation aid, Figure 11.2(c).
