| 摘要 |
PURPOSE:To prevent the intensional call from a third person and increase reliability of the system by checking incoming data by means of clock pulses initiated at a fixed time interval. CONSTITUTION:When data terminal DT sends an ID recognition No. to the center side through switchingboard EX at time interval to, synchronous output appears on lead OUTA of receiver REC and circuit CLK is initiated by means of operation of memory circuit MB; then, the output clock pulse is supplyed to gate A at constant time interval T. When the output of OUTA is supplyed to gate A and both time intervals are the same, output appears on gate A, so that the output data of REC is stored in circuit MA. ON the other hand, gate A is not operated by the intensional call of a third person and an alarm is generated by means of operation of lamp AL and buzer BZ acccording to operation of gate F. |
