| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a circuit capable of monitoring BER without using a timer. <P>SOLUTION: An error term T<SB>e</SB>of input data is detected by a parity check unit 1 and an error term detection unit 2, and a maximum value T<SB>emax</SB>in a plurality of these error period is detected by an error period memory 3 and an error period maximum value retrieval unit 4. This maximum value T<SB>emax</SB>is then converted into a corresponding estimate error rate BER<SB>max</SB>by a Te-BER conversion table 5 and when the estimate error rate BER<SB>max</SB>becomes greater than an alarm detection threshold Th<SB>d</SB>, an SF/SD 6 issues an alarm ALM. When the estimate error rate BER<SB>max</SB>becomes equal with or lower than an alarm cancel threshold Th<SB>r</SB>thereafter, the alarm ALM is canceled. Furthermore, an error free retrieval unit 7 is initiated when the alarm ALM is issued, and the alarm ALM is canceled when a period during which the error term T<SB>e</SB>is not changed, exceeds a period T<SB>eThr</SB>corresponding to the alarm cancel threshold Th<SB>r</SB>. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
