Patent ID: 7315590

Claim:
A method for measuring a frequency error being a difference between a reference frequency of a receiver and a reference frequency of a sender comprising the steps of: counting how many chips of complex base band signals are to be input; performing a rotation correction in a step-by-step manner by rotating a phase of said complex base band signal on a complex plane at a phase rotation angle at m-stages each being slid by a reference rotation angle being an angle obtained by dividing a rotation angle (2π) of a revolution to M portions every time said counted number of the chips increases by K-chips; producing a multiplied value by multiplying the rotation corrected complex base band signals by spread signals; producing a correlation value of I component of said multiplied value and a correlation value of Q component of said multiplied value by adding said multiplied value in an accumulative manner for every I component and every Q component during one symbol period; calculating a power value of the complex base band signal in said one symbol period based on said correlation values of said I component and said Q component; and selecting said reference rotation angle so that said power value becomes maximum.