Patent ID: 6816543
Filing Date: 2004-11-09
Classification: H04B

Abstract:
A spread spectrum communications apparatus for receiving an RF spread spectrum modulated signal and obtaining a primary modulated signal modulated by an information signal, comprising:a) an RF receiver for receiving said RF spread spectrum modulated signal, b) a de-spreader for generating said primary modulated signal from said RF spread spectrum modulated signal output from said RF receiver by using a de-spreading code, and c) a sync circuit for acquiring synchronization to synchronize said RF spread spectrum modulated signal and the de-spreading code, by performing a first synchronization acquisition operation by detecting a correlation value of said RF spread spectrum modulated signal and the de-spreading code in the synchronization acquisition operation at every sequential change of a phase value of the de-spreading code, and by performing a second synchronization acquisition operation, wherein the first synchronization acquisition operation judges a maximum value of the correlation value from the correlation values for the number of times of detection in the synchronization acquisition operation, and a phase value corresponding to the maximum value, calculates a sum of the correlation values for the number of times of detection, calculates an average of the correlation values from the sum, and judges if the synchronization acquisition has been established or not by comparing the maximum value with a sum of the average and a specified threshold level, and the second synchronization acquisition operation chances the phase of the de-spreading code before and after a phase corresponding to the maximum value.