Patent ID: 9214921
Filing Date: 2015-12-15
Classification: H03H

Abstract:
1. A sampling rate conversion device which converts an input digital signal sampled at an input sampling rate into an output digital signal sampled at an output sampling rate, comprising: a position coordinate difference calculation section calculating a position coordinate difference Dk between a position coordinate of the input digital signal close to a position coordinate Tk of the output digital signal Yk and the position coordinate Tk; an FIR coefficient memory storing, with respect to a finite impulse response-low pass filter (FIR-LPF) having such a characteristic as to cut off frequency components equal to or higher than ½ of the output sampling rate, an FIR coefficient F(z) of the FIR-LPF when a position coordinate of an impulse input to the FIR-LPF is z=0, wherein when the position coordinate difference Dk is input, the FIR coefficient memory outputs FIR coefficients F (Zk(q)−Tk) corresponding to a position coordinate differences (Zk(q)−Tk) with respect to Zk(q) (q=1, 2, . . . , p) representing position coordinates of a certain number (p) of input digital signals Xk(q) existing in the vicinity of the position coordinate Tk of the output digital signal Yk; and an FIR computation unit computing Yk=F(Zk(1)−Tk)*Xk(1)+F(Zk(2)−Tk)*Xk(2)+ . . . +F(Zk(p)−Tk)*Xk(p) and obtaining the output digital signal Yk, wherein C is a constant, M and N are positive integers prime to each other, a sampling period of the input digital signal is C·M, a sampling period of the output digital signal is C·N, and the position coordinate difference calculation section includes: an input accumulator accumulating M and outputting an accumulated value Sm; an output accumulator accumulating N and outputting an accumulated value Sn; an accumulated value comparator making the input accumulator accumulate M when Sm−Sn is equal to or less than a predetermined value, making the output accumulator accumulate N when Sn−Sm is equal to or less than a predetermined value, and outputting, as the position coordinate difference Dk, Sn−Sm obtained when the output accumulator is made to accumulate N.