METERING PULSE GENERATION CIRCUIT OF AGRICULTURE AND FISHERY SWITCHING SYSTEM

摘要

PURPOSE: A metering pulse generation circuit of an agriculture and fishery switching system is provided to prevent a billing equipment from not being initialized due to under voltage. CONSTITUTION: A first excessive voltage protection part(24) protects the circuit against excessive voltage flowed from tip and ring terminals and is connected with an output test relay(26a) for the output test of a network relay(26). A second excessive voltage protection part(28) connected with a SLIC(30) interrupts excessive voltage flowed from a PRS relay(26d). A combo codec(32) carries out the transmitting and receiving of a HWX signal, a HWR signal, a FSX signal and a CLK signal. A metering pulse generation circuit(36) generates a clock of 12/16 kilohertz after receiving a clock of 2 megahertz. A triplex decoder(14) connected with a triplex addressable latch(20) is enabled by a card enable signal(CARD EN). The triplex addressable latch(20) latches and outputs signals of DW0-DW3.