| 摘要 |
<p>A bridge-lifter circuit arranged to match the impedance of party-line off-hook transmission facilities to the impedance of a common transmission line. Circuitry is provided so that when one party-line transmission facility is off-hook a high impedance is switched in series with the remaining on-hook party-line facilities to effectively remove the bridged impedances from across the off-hook facility. When more than one transmission facility is off-hook, an impedance matching transformer, arranged to pass d.c. supervisory signals, is serially inserted between the common transmission line and off-hook party-line transmission facilities to match the combined impedances of the bridged facilities to the impedance of the common line.</p> |
