Patent ID: 6556620
Filing Date: 2003-04-29
Classification: H04B

Abstract:
A device for performing synchronization acquisition in a spread spectrum communication system by detecting a specific timing in received signals that is spread by a specific spreading code, said synchronization acquisition device comprising:a correlation detecting means for calculating correlation values between digital data, which have been obtained by A/D converting said received signals that have been demodulated, and said specific spreading code; a timing-correlation value storing means for storing both data of correlation values and associated timings; a first multiplying means for multiplying correlation values obtained by said correlation detecting means by a coefficient K(0a second multiplying means for multiplying correlation values read from said timing-correlation value storing means by a coefficient (1âˆ’K) and outputting the result; an adding means for adding values outputted from said first multiplying means and values outputted from said second multiplying means and outputting the result; a selecting means for selecting and outputting one of the output of said adding means and the output of said first multiplying means; and a control means for: in the first correlation value calculation, storing in said timing-correlation value storing means only data of the N highest-ranking correlation values of a fixed interval portion obtained in said correlation detecting means, N being a predetermined number; and in the second and subsequent correlation value calculations, determining whether or not a timing for which a correlation value is obtained in said correlation detecting means is stored in said timing-correlation value storing means; instructing said selecting means to output the output from said adding means to said timing-correlation value storing means if the timing is stored in said timing-correlation value storing means; instructing said selecting means to output the output from said first multiplying means to said timing-correlation value storing means if the timing is not stored in said timing-correlation value storing means and if the associated correlation value is greater than the Nth correlation value PN stored in said timing-correlation value storing means; instructing said timing-correlation value storing means not to carry out any processing on output from said selecting means if the timing is not stored in said timing-correlation value storing means and if the associated correlation value is equal to or less than the Nth correlation value PN that is stored in said timing-correlation value storing means; and outputting the timing information stored in said timing-correlation value storing means upon completion of correlation value calculations equal in number to a prescribed number of averages.