Abstract: A ranging system using the correlation between two spread spectrum wave signals includes an antenna for receiving from a single radio source two spread spectrum modulated signals simultaneously transmitted in the same code on carrier waves of different frequency, a multiplier for multiplying the received signals by each other to generate two continuous signals of frequencies respectively equal to the difference and the sum of the carrier waves of the spread spectrum signals, and a data processing computer for measuring the phases of the two continuous signals with reference to a reference clock at the receiving station so as to remove the ambiguity at the time of range measurement.