Patent ID: 7035605

Claim:
A method for controlling frequency of a local oscillator in a DS-CDMA type receiver, the method comprising: transforming a known spread spectrum signal into a sampled digital signal formed of symbols with a despreaded frequency spectrum; determining a residual frequency error f e for each symbol including a first residual frequency error f e1 ; filtering the residual frequency errors; correcting the frequency of the local oscillator with the filtered residual frequency errors; storing the first determined residual frequency error f e1 ; determining an average of absolute values of a predetermined number of successive residual frequency errors; and comparing the average with a threshold, and if the average is greater than or equal to the threshold, the local oscillator frequency is corrected using an error equal to −sgn(f e1 ) (1/T−|f e1 |) , where sgn is the sign function, | | is the absolute value function and T is duration of a symbol before determining the next residual frequency error associated with the next symbol.