| 摘要 |
PURPOSE:To obtain a multiplex transmission system which is not affected by external noises and prevented from the limitation of the pulse width of transmission signals by using a photocoupler element as a terminal branch device for a multidrop circuit. CONSTITUTION:A digital data signal transmitted from a central office which is not shown in the drawing through a common transmisson line is converted into an optical signal by a light emitting diode LED constituting a terminal branch device. Said optical signal is converted again into an electric signal by the 1st phototransistor and sent to a succeeding terminal branch device through a common transmission line and, simultaneously, a part of the optical signal is converted into an electric signal by the 2nd photodiode PT2 and sent to an unshown terminal device. Said constitution enables the multiplex transmission system to remove a ground loop without using a pulse transformer, so that external noises can be removed without the limitation of pulse width of transmission signals. |
