Abstract: A correlator and a detection method are presented. The detection method is modified from "Appollo" ranging system and suitable specifically for tone-code mixed ranging system. In the "Appollo" system the maximum likelihood detection was used, while in the present detection method setting of detection threshold is float.In comparison with"Appollo"system it has obvio us advantages: cor-relation loss decreases by 6dB and configuration is very simple. These feat-ures have been proved in use.

Key words: Pseudo-random code, Range finding, Correlation technique, Threshold condition, Computation.