PURPOSE: To find a pitch predictive factor with high accuracy and in a short time, by finding a pitch cycle from a data of one frame, and finding an autocorrelation value from a necessary minimum data of two frames.
CONSTITUTION: All of data x(0), x(1),..., x(k-1) are accumulated in an internal RAM34 via an internal bus 33. Next, an input signal x(j) is read out from the RAM34, and is fetched in an A register 35, and an input signal x(i+j) is fetched in a B register 36, and the arithmetic calculation of the x(j) and the x(i+j) is performed at an arithmetic circuit 37, and a result is inputted to a D register 38. The maximum value XMAX is detected out of found autocorrelation values R(a), R(a+1),..., R(b). The autocorrelation value is calculated by using the A register 35, the B register 36, the arithmetic circuit 37, and the D register 38, and the pitch predictive factor can be calculated.
TOMITA YOSHIHIRO
UMIGAMI SHIGEYUKI
