专利名称：FILTERING发明人：COOK, John, Wolsey申请号：EP95907086.3申请日：19950201公开号：EP0742972B1公开日：19980930
摘要：A twisted-pair telephone line (100) is connected to a conventional telephone (at103) via a low-pass filter and (102) equipment (at 106) for receiving signals in an upperfrequency range e.g. 25-1000 kHz via a high-pass filter (105). The low pass filter (105) isprimarily passive (to allow passage of line power, ringing and signalling voltages) but, toimprove matching to non-resistive line and telephone impedances, at least the main partof the filter T4, T5, C4A/B, C5A/B, C6A/B, C7A/B is flanked by impedance converters (300,400) in which amplifiers IC2, IC4 having an appropriate transfer function feed voltagesback into the line via transformers T3, T7 through which power, ringing and dialling maypass unimpeded.
申请人：BRITISH TELECOMM
地址：GB
国籍：GB
代理机构：Lloyd, Barry George William
更多信息请下载全文后查看
因篇幅问题不能全部显示，请点此查看更多更全内容