| 摘要 |
PURPOSE:To ensure the effective transmission of the information between the master unit and the slave units, by transmitting the synchronous signal and the information signal to the same information line and in correspondence to the pulse train having two different levels and then having the comparison between these levels at the reception side to isolate the synchronous signal from the information signal. CONSTITUTION:The information to be sent to the slave unit from the master unit of the key telephone equipment plus the information to the master unit from the slave unit are divided into two blocks. And the ramp to the slave unit from the master unit plus the working information of the amplifier are sent in multiplication to the information line and in the form of the pulse train having the different levels. At the same time, the button selection, the holding and the dial information are sent to the master unit from the slave unit via the call line. Then the call current of the call line is varied via the constant current circuit within the slave unit and as shown in the table, and thus the button selection, the holding and the dial information are identified by the slave unit detecting circuit within the master unit. As a result, the information transmission is carried out between the master unit and the slave units with a reduced number of wiring cables and in a high efficiency. |
