"Paul Tomblin" wrote in message ...
In a previous article, said:
How does the system know which are the outer dme "targets"? Is it
just the weaker dme transmissions that are received by the ground
station that are dropped? Stan

By response time. It sends out a signal, and the first N to respond are
tracked.

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No, Paul, the DME ground station does not initiate the exchange.
The ground stations only reply to interrogations from aircraft.
See Bob Noel's correct explanation elsewhere in this thread.
When the ground station is not being interrogated, it increases
its receiver sensitivity until it "replies" occasionally to random noise.
As more actual interrogations are received, the ground receiver
reduces its sensitivity to limit the rate of replies transmitted.