| 摘要 |
PURPOSE:To enhance the function of the key telephone system by securing the cordless part between the main device and the telephone of the key telephone system as well as having multiplication of the signal. CONSTITUTION:Among the signals which are transferred between the main device and the telephone, such signals which never occur at one time and are required for the talking action as the call signal, the hook signals before and after the call signal, the dial signal, the incoming signal and others like the normal telephone unit are referred to as the first signal. And the signal which can be generated simultaneously with the first signal and is proper to the key telephone system is referred to as the second signal. Then the second signal is turned to upper and lower side bands 4 and 2 which are modulated by subcarrier wave 3 and then frequency-multiplifed with the first signal. These signals such distributed are modulated by main carrier wave 5 to be transferred between the main device and the telephone unit. |
