| 摘要 |
<p>839,581. Telephone transmission. SIEMENS EDISON SWAN Ltd. Nov. 21, 1958 [Nov. 26, 1957], No. 36844/57. Class 40 (4). At a tandem exchange wherein an incoming 4-wire junction is connected to an outgoing 4-wire junction by a 2-wire link TW, each terminating set comprises a hybrid coil HCP, HCQ with a balancing network and a repeating coil RCP, RCQ arranged as shown. A D.C signalling circuit exists over the primary windings of the repeating coils, polarized relay DD being energized by reversal of current when relay D (not shown) pulls up.</p> |
