| 摘要 |
PURPOSE:To improve a terminal ringing return loss by selecting ans using a balancing network of the best matching for a calling subscriber at every time when a call is connected. CONSTITUTION:The two-wire/four-wire converter circuit is composed of subscriber's line concentration switch SDSW on a space-division two-wire system, hybrid transformer H-TR, balancing network BNW, and time-division switch network TDSW with a distributing switch function. At this time, this circuit is equipped with balancing network BNW1 designed to match with a subscriber's line without general loading, balancing network BNW2 designed to match with a subscriber's line with long-distance loading, and control circuit CTL which switches between networks BNW1 and BNW2 connected to transformer H-TR. Preparing balancing networks separately improves the return loss to more than approximate 5 to 6dB. |
