| 摘要 |
PURPOSE:To receive the data signal superposed on a power supply line with no effect of the load fluctuation, by obtaining a single pulse in response to the coincidence between the pulse delivered in response to the front edge differential pulse of a received signal and the back edge differential pulse. CONSTITUTION:A power supply circuit 13 is provided at the side of a slave unit of a key telephone, and a constant voltage load system is applied for the slave unit. While the changing speed of the data signal (a) which is transmitted through a power supply line 11 and with superposition on another signal is higher than the changing speed of voltage, and accordingly the rise and fall of the signal (a) are detected by the 1st and 2nd differentiating circuits DIF1 and DIF2 respectively. The outputs of the circuits DIF1 and DIF2 are supplied to a pulse generating circuit 8 and a Schmitt circuit 7. The signals produced through the circuits 8 and 7 are fed to a coincidence circuit 9. These two signals are then supplied to a pulse generating circuit 10 in the form of the trigger signals after the coincidence is obtained between both waveforms. Thus a desired receiving output is obtained. |
