| 摘要 |
PURPOSE:To obtain a code error alarm output without dispersion, by counting the number of code error pulses at every cycle of a clock selected by a timer switching selector, outputting an overflow signal when a counted value arrives at a prescribed value, and outputting a code error alarm signal when a prescribed number of overflow signals are detected. CONSTITUTION:When transmission quality is deteriorated and the error code pulse is inputted to a code error detecting circuit A1, the code error alarm signal 6 is outputted through a path of (1) (2) (3) (4). Simultaneously, a timer switching selector circuit (c) selects the output of a timer circuit (d2), and the code error detecting characteristic of the code error detecting circuit A1 is changed to a characteristic shown in continuous line, and code error alarm is surely outputted. Meanwhile, when the code error pulse disappears, the code error alarm signal 6 is released through the path of (4) (5) (6) (1), and simultaneously. the timer switching selector circuit (c) selects the output of a timer circuit (d1), and the code error detecting characteristic of the code error detecting circuit A1 is changed again to the characteristic shown in an alternate long and short dash line, and no code error alarm is surely outputted.
|
