| 摘要 |
<p>PURPOSE:To ensure an economical control for call signal of a multiparty telephone set, by installing a reference signal generating circuit and a declining circuit to the multiparty trunk and then switching the ratio of decline for the period of output signal of the reference signal generating circuit. CONSTITUTION:Counters CN1, CN10 and CN100 decline the period of the reference signal delivered from a reference signal generating means CLK. At the same time, the information given from a control device is stored in memory circuits M1, M10 and M100 respectively, and the ratio of decline is switched for the period of the reference signal. When the corresponding party line telephone is called out among plural party line telephones connected to a multiparty telephone set circuit, the period of the reference signal is declined by a declining means to extract a call signal. This call signal is transmitted through a multiparty trunk.</p> |
