| 摘要 |
As a function of the occurrence of first square-wave signals the circuit arrangement generates a time window and monitors the appearance of second square-wave signals during the time span defined by the time window. If the second square-wave signals appear during the time window, appropriate output signals are generated. The circuit arrangement contains an integrator which is reset by the first square-wave signals and released subsequently. A comparator compares the voltage at the integrator with two threshold values. If the first threshold valve is exceeded, the time window is opened, and it is reclosed if the second threshold value is exceeded. The threshold values are generated by means of a switchable voltage divider. This voltage divider is switched by means of a flip-flop if the voltage at the integrator exceeds the first or second threshold value, respectively.
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