| 摘要 |
PROBLEM TO BE SOLVED: To provide a pole change detector for a track circuit capable of carrying out always stable detection. SOLUTION: A mark signal of one point is rotated in a ring buffer 22 of N-cells by a clock signal of N-tuple frequency of track circuit frequency, and one point is added into the cell where the mark signal exists when a rising signal from the zero cross of a track circuit current is generated. One point is subtracted upon the lapse of M-seconds from the time of adding one point into each cell. The sum X of the number of points added in the past M-seconds on all the N-cells is obtained. Further, the N-number of the sums of the number of points added into the P-number of cells in the past M-seconds are obtained, and a maximum value Y is selected from them. In the case where Y exceeds a specified ratio in relation to X, the approximately center cell number of P-number of cells is set as the rising average phase point of the track circuit current. The latest average phase point and the oldest average phase point are compared and converted into an actual phase angle, and the pole change of the track circuit current is determined when the actual phase angle is changed by 180 deg..
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