METHOD AND DEVICE FOR DETECTING OUT OF SYNCHRONISM

摘要

PROBLEM TO BE SOLVED: To provide the out of synchronism detector with a small circuit scale. SOLUTION: Detection signals xk , yk are input terminals 1, 2. An absolute value arithmetic circuit 3 provides an output of an absolute value |xk | of the signal xk and an absolute value arithmetic circuit 4 provides an output of an absolute value |yk | of the signal yk . A constant multiplier 5 multiplies the value |xk | with a multiple of (c) to provide an output of c|xk | and a constant multiplier 6 multiplies the value |yk | with a multiple of (c) to provide an output of c|yk |. A comparator 7 provides an output of '1' in the case of |yk |>c|xk |, and a compactor 8 provides an output of '1' in the case of |xk |>c|yk |. An OR circuit 9 provides an output of ORed outputs of the two comparators and a counter 10 counts number of times when the OR output is '1'. A comparator 11 provides an output of out of synchronism when number of times exceeds a threshold level L.