摘要 |
A distance measuring system in which a first station radiates a modulated carrier wave and a second station receives that wave, and retransmits the modulation on a carrier wave back to the first station, which compares the phases of the original and received modulations. The second station includes a digital counter (19) which accumulates clock pulses (22) denoting the period of the modulation and a second counter is (26) incremented and decremented to reproduce the modulation for retransmission thereof. |