Patent ID: 7016400

Claim:
A digital matched filter for despreading on reception side a received signal sequence having been spread on transmission side, comprising: received signal holding means for successively holding a predetermined number of samples among samples constituting said received signal sequence input in time-series manner; spreading code generating means for generating a spreading code sequence for said despreading; and correlation value calculating means for calculating a correlation value between said predetermined number of samples held in said received signal holding means and said generated spreading code sequence, said correlation value calculating means including first product-sum calculating means for calculating a correlation value between a part of the predetermined number of samples held in said received signal holding means and a part of the generated spreading code sequence corresponding to said part of the predetermined number of samples held in said received signal holding means, second product-sum calculating means for calculating a correlation value between a remaining part of the predetermined number of samples held in said received signal holding means and a remaining part of the generated spreading code sequence corresponding to said remaining part of the predetermined number of samples held in said received signal holding means, and decision means for comparing the correlation value output from said first product-sum calculating means with a predetermined threshold value to stop calculation by said second product-sum calculating means when said decision means decides that the correlation value output from said first product-sum calculating means does not exceed said predetemiined threshold value.