| 摘要 |
PURPOSE:To accurately detect various monitor signals, by preventing missing and misdetection of various monitor signals due to noise, through the decision by majority for the scanning of lines before the result of the last but one time. CONSTITUTION:A line status signal 108 is sequentially shifted with a shift register 100 in accordance wth a clock pulse from a clock generation section 101, and scanning signals for this time, previous time and last but one time are outputted as a parallel data on signal lines 111-113. The polarity of the scanning signal is discriminated with a decision by majority discrimination section 102 receiving this parallel data. When it is Z polarity, logical 1 is applied to a Z polarity detection shift register 103 and logical 0 is applied to an A polarity detection shift register 104, and when it is the A polarity, the inverted logicals 0 and 1 are applied to the registers 103 and 104. The output of the registers 103 and 104 is applied to a callout signal detecting section 105, a pulse detecting section 106 and an call end signal detecting section 107 to accurately detect the respective call signal, call end signal and pulse width. |
