| 摘要 |
1,026,306. Automatic exchange systems. STANDARD TELEPHONES & CABLES Ltd. Aug. 15, 1963 [Aug. 23, 1962], No. 32297/63. Heading H4K. In a switching network in which each stage comprises a number of switching blocks KVA, KVB ..., Fig. 1, each block of one stage being connected by a single trunk to each block of the next, an idle through-route between a subscriber's line and a transmission path is selected by the application of markings at both sides of the network to guide wires associated with the trunks. In Fig. 1A, which shows two stages only, each switching block includes a PNPN diode 23 associated with an electromechanical switch 21. A forward " offering " signal applied at 27 fans out through all the idle trunks, and a backward " catching " signal applied at 28 brings about the operation of one diode in each stage to select a single route, the first diode to fire preventing the firing of any other in that stage. In the block KVB1, Fig. 2, in the idle condition an offering signal on an incoming guide wire mw, for example, passes forward to all the outgoing guide wires m1 ... mu. If a catching signal is received on one of the guide wires k1 ... ku an AND gate A1 opens and allows the signal to pass to the preceding stage, and at the same time relay K energizes to control switching. A control circuit AGB ensures that only one block can retransmit the catching signal. The circuits of Fig. 2 are shown in greater detail in Fig. 3 (not shown). The same guide wires may be employed for the offering and catching signals, Fig. 4 (not shown). |
