FREQUENCY STABILITY DECIDING METHOD FOR NETWORK CLOCK AND CIRCUIT THEREFOR

摘要

PROBLEM TO BE SOLVED: To decide a degree of frequency stability in an early stage by preventing a wrong decision.;SOLUTION: First of all, a shortest detection term T1 is set (201), the degree of frequency stability is found (202) and compared with a threshold (203). In such a case, when the degree of frequency stability is within the threshold, stability OK is decided (204) and stability decision in the detection term T1 is repeated. When the degree of stability exceeds the threshold, the term T1 is changed to a longer detection term T2 (205), and the degree of frequency stability is found (206) and compared with the threshold (207). When the degree of frequency stability is within the threshold, stability OK is decided (208) and processing is returned to the stability decision in the term T1. When the degree of stability exceeds the threshold, the term T2 is changed to a longer detection term T3 (209), the degree of frequency stability is found (210) and compared with the threshold. When the degree of frequency stability is within the threshold, stability OK is decided (212) and the stability decision is performed back to the detection term T1. When the degree of frequency stability exceeds the threshold, stability abnormality is decided (213).;COPYRIGHT: (C)2004,JPO