| 摘要 |
<p>PURPOSE:To perform the test of a monitoring function profitably by inserting an error code to a signal relating to the monitoring function out of communication signals via a monitor signal insertion circuit. CONSTITUTION:Communication is performed by stopping an error insertion control circuit 4 from the outside and sending a normal signal without inserting an error to a monitor signal. Meanwhile, a delivery test or periodical inspection is performed by driving the error control circuit 4 from the outside, and sending it by inserting the error to the monitor signal via the monitor signal insertion circuit 3. Receivers 6-9 operate the monitoring function by the monitor signal to which the error is inserted. For example, when the monitoring function is a synchronous monitoring function, the error is inserted to a synchronizing signal, therefore, no synchronous detection is performed when the synchronous monitoring function is operated normally, and a synchronous alarm is issued after a prescribed operation is performed. Also, in an error correction circuit, a signal outputted by performing a corrective operation is compared with a signal before the error is inserted. In such a manner, it is possible to test the normal/abnormal state of the monitoring function.</p> |
