Pulse-hyperbolic location system using three passive beacon measurements

A passive radio ranging system for locating a station at a target position and an unknown location, said system comprising a radio frequency pulse transmitter means at a first known location for periodically transmitting a discrete number of cyclic pulses recurring at a system identifying pulse repetition rate, at least one radio frequency pulse repeater means at another separated but known geographical location for receiving pulses which recur at said system identifying pulse repetition rate and for selectively dropping some and retransmitting other of said pulses, said stations being identified by the pulses which are dropped and those which are retransmitted by that station, and calculating means at said target position responsive to time differentials required to receive pulses from said first known location and said repeater means at said another location for calculating the location of said target means.

A radar location system comprising at least three stations transmitting and receiving on a particular frequency, means at a first of said stations for transmitting a first and continuous stream of pulses formed by interrupting said frequency at a cyclically recurring station identifying rate for an indefinite period of time during which said system is operating, means at a second of said stations responsive to the receipt of a predetermined number of pulses in said first continuous and indefinite stream of pulses for thereafter repeating pulses in said first stream by pulses by interrupting said frequency at a rate which identifies the second station, thereby forming a second stream of pulses lagging after said first stream of pulses by a time period at least partially reflecting the distance between said first and said second stations, and means at a third of said stations responsive jointly to the receipt of said first and second stream of pulses recurring at the rate which identifies the first station for calculating the location of said third station.

A radar location system comprising at least three stations, means at a first of said stations for transmitting a first stream of pulses which recur at a station identifying rate, means at a second of said stations responsive to the receipt of a predetermined number of pulses in said first stream of pulses for thereafter repeating each pulse in said first stream of pulses, thereby forming a second stream of pulses lagging after said first stream of pulses by a time period at least partially reflecting the distance between said first and said second stations, means at a third of said stations responsive jointly to the receipt of said first and second stream of pulses for calculating the location of said third station, and means at said third station responsive to a receipt of less than said predetermined number of pulses in said first stream of pulses for generating cyclically recurring first window pulses coinciding with said first stream of pulses and ocurring at said station identifying rate, and means for rejecting any pulses which does not coincide with a corresponding one of said first window pulses.