| 摘要 |
A transmission system includes a transmission path from a transmitting station to a receiving station for both voice telephone service occupying the frequency spectrum below a predetermined frequency f1 and for data service occupying the frequency spectrum above another predetermined frequency f3, where f3 is substantially higher than f1, a plurality of telephone sets at said receiving station connected in parallel with one another to the transmission path, and where each of the telephone sets has an on-hook state which presents a substantially infinite resistance to the transmission path and an off-hook state which presents a predetermined resistance R to the transmission path. A plurality of separate and substantially identical multi-pole low-pass filters are provided for connection between the transmission path and respective ones of the telephone sets, where each of the low-pass filters has a -3 dB frequency f2 which lies between f1 and f3, and a characteristic impedance of substantially (n*R), where n is a number equal to at least 2.4, thereby reducing the effect of low impedances that develop at frequencies below f1 because of resonances that occur between f1 and f2 with at least one but less than all of said telephone sets off-hook.
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