Preferably, the processor is configured to calculate correlation power Pk PN between a PN scrambling sequence and a received signal for a sample Sk based on: P k PN = ??? m ??? I ??? ??? n = 0 N - 1 r ( Nm + n ) c * ( Nm + n - k ) ??? where N is a predefined constant and c(???) represents values corresponding to PN scrambling sequences.