Abstract:The modernization GPS system employes new Binary Offset Carrier (BOC) modulations, which achieve high performance in anti-jamming and code tracking. BOC modulations can be write as a sum of two coding signals. This can be generalized as multiple Spread Spectrum Direct Sequence (SS-DS) modulations transmitted by single radiator. This paper suggest that multiple spread spectrum signals should be processed as a new single signal for achieving high performance in anti-jamming and code tracking. Expression for error of code tracking is given in terms of signal parameters. Values of signal parameters for 3 dB outperform in code tracking are given finally.