| 摘要 |
PURPOSE:To vary the bit rate of a monitoring signal which is inputted to a stand-by system over the entire permissible range of the standard of the stand-by system and to monitor the operation of the stand-by system by varying the frequency of a clock signal which is inputted to a pattern generating circuit. CONSTITUTION:A coincidence detecting circuit 3a controls the clock signal Ca for a specific monitoring time so that the bit rate of a monitoring signal Ma outputted from the pattern generating circuit 2a varies over the entire permissible range of the standard. Namely, the coincidence detecting circuit 3a outputs a frequency control signal FC to a variable clock frequency source 1a to control the frequency of the clock signal Ca. Consequently, the monitoring signal Ma which varies the bit rate over the entire permissible range of the standard is inputted to the stand-by system 4 for the specific monitoring signal and the stand-by system monitoring output signal Na corresponding to the signal Ma is outputted from the stand-by system 4. This monitoring signal Ma and stand-by system monitoring output signal Na and matched, bit by bit, by the coincident detecting circuit 3a to judge that the stand-by system 4 is normal when both signals coincide with each other and abnormal when not. |
