Digital orthogonal detection manner, digital orthogonal detection device and ultrasonic diagnostic device

摘要

PROBLEM TO BE SOLVED: To provide a digital orthogonal detection method and device capable of easily varying a reference frequency. ;SOLUTION: Coefficient sets k1i, k2i, k3i, k4i, for calculating, through interpolation operations and from four digital data d11, d12, d13, d14, interpolation digital data E1 at each time that divides a digital data sampling period Ts by (m), are stored in a coefficient table 105. Frequency varying parameters (n) are outputted from a timing control circuit 103 in a period of 'Ts +n (Ts/m)' and are accumulated and added together by an accumulator 104 that performs cyclic cumulative additions from '0' to 'm-1', and the coefficient sets K1i, K2i, K3i K4i are selected and set according to a sum (i) to calculate the interpolation digital data E1. The interpolation digital data E1 calculated, or interpolation digital data '-E1' obtained by inverting the sign of the data E1, or '0', is selectively outputted. Thus, the reference frequency of digital orthogonal detection can be varied finely by varying 'n'. Use of this method in an ultrasonic diagnostic device allows dealing with spectrum shifts.;COPYRIGHT: (C)1997,JPO