TELEMETRY SYSTEMS EMPLOYING ACTIVE TRANSPONDERS

摘要

A telemetry system is provided which enables positioning of a vehicle equipped with an interrogator relative to at least two active transponders whose relative coordinates are initially unknown. The separation of the transponders is initially measured by interrogating the transponders with a code whereby one of the transponders produces a single response and the other produces two consecutive responses, the first responsive to reception of the interrogation signal and the second responsive to the reception of the response produced by the other transponder. By providing a further vehicle with a transponder similar to the reference transponders, the further vehicle can be positioned simultaneously with the main vehicle. The invention is particularly applicable to positioning marine and/or underwater vehicles relative to submerged transponders although it is also applicable to landing aircraft under poor visibility conditions.