Patent ID: 6040801
Filing Date: 2000-03-21
Classification: G01S

Abstract:
In a radio transmitter-receiver combination of a R-.theta. type navigating system having a predetermined signal-to-noise threshold below which signals cannot be transmitted, received, modulated, and displayed, the method comprising:generating a carrier wave at the transmitter;generating like groups of coded binary pulses at the transmitter and at the receiver;modulating said carrier with said coded binary pulses, said pulses being of such small increments of energy and so widely distributed in time that the signal-to-noise ratio at the receiver is below said threshold;combining at the receiver the received and the locally generated groups of pulses;shifting at the receiver the relative time phase of the two groups of pulses so that the two groups cross-correlate, multiplying one group voltage by the other, and integrating the product until the stored signal exceeds said threshold; andfinally calibrating said relative phase shift in terms of distance between the transmitter and receiver.