A method for synchronizing a receiver (1) with a transmitted code-modulated spread spectrum signal, uses at least one reference code (r(x)), which corresponds to a code used in the modulation, and determines the frequency shift of the transmitted signal and the code phase of the code used in the modulation. In the method, a correlation step is taken to form a correlation function matrix on the basis of the received signal and said reference code. A non-coherent search matrix is formed of said correlation function matrix. In the method, elements in said non-coherent search matrix are modified on the basis of at least one statistical property of the elements in said non-coherent search matrix, and/or high-pass filtering is performed before the formation of said correlation function matrix. The invention also relates to a system and a receiver in which the method is applied.