| 摘要 |
PURPOSE:To carry out the 2-wire/4-wire exchange according to one of various systems, by providing with connection one of the resistance attenuators at the carrier output side or the local office side of the hybrid coil. CONSTITUTION:Resistance attenuator PAD2 is connected as shown by the solid lines, and each contact is connected at shown in the figure. As a result, the input signal of OdB receives the attenuation of -4dB at resistance attenuator PAD1 and hybrid coil 3 each to be then transmitted to telephone 1. And the output of telephone 1 receives the attenuation of -4dB at coil 3 and attenuator PAD1 each to be delivered. On the other hand, if attenuator PAD2 is distributed between capacitors C3/C4 and contacts 4W14/4W15 as shown by the dotted line, the input signal receives the attenuation of -12dB in all at attenuators PAD1, PAD2 and coil 3 each to be sent terminal unit 4. And the output of unit 4 receives the attenuation of -8dB in all at attenuator PAD2 and coil 3 each, and is then delivered. In such way, the 2-wire/4-wire exchange is possible according to one of various systems. |
