Synchronization acquisition device for both preventing erroneous detection due to noise and reducing required storage capacity

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(0<K≦1) and outputting the result;
• a second multiplying means for multiplying correlation values read from said timing-correlation value storing means by a coefficient (1−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.