Patent ID: 6891885
Filing Date: 2005-05-10
Classification: H04B

Abstract:
1. A correlation circuit for spread spectrum communication for obtaining a correlation output from a spectrum-spread received signal, said circuit comprising: an A/D converter for converting said received signal to a digital signal from an analog signal and sampling the signal; a memory for storing an output from said A/D converter; an input signal register, having a variable transfer speed of a shift, for shifting and outputting the input signal from said memory at a specified speed; spread code registers, prepared for a necessary number of users, for shifting and outputting a generated spread code; a sum of products calculator for multiplying and adding the input signal outputted from said input signal register and the spread code outputted from said spread code register at a specified number of times said sampling speed; and a controller for: controlling the transfer speed of the shift of one sample in said input signal register in order to hold a sufficient time for completing calculation of a sum of products with respect to all a plurality of users in said sum of products calculator, when the plurality of users more than a specified number of users exist in the same phase of the input signal from said memory; subsequently controlling and setting said transfer speed to be higher than said specified speed before compensating for a delay time within one symbol, when the users less than said specified number of users exist in the same phase; and controlling and selecting the spread code to be outputted to said sum of products calculator in accordance with the number of users in the same phase.