One embodiment of the invention provides a receiver for use in a navigation system comprising multiple transmitters. Each transmitter transmits a positioning signal comprising a pseudo-random noise (PRN) sequence corresponding to the respective transmitter. The receiver comprises a code module for supplying multiple PRN sequences corresponding to the respective multiple transmitters; and a correlator for correlating the PRN sequences supplied by the code module with an incoming signal. The multiple PRN sequences are based on a single Sidelnikov/Lempel/Cohn/Eastman (SLCE) generative sequence uSLCE, and each of said multiple PRN sequences, denoted ui satisfies the equation: ui=uSLCE⊕TiuSLCE, where ⊕ indicates element by element binary XOR addition, and Ti indicates a cyclic shift of i chips.