GB600458A - Telecommunication systems - Google Patents

Abstract

600,458. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd. April 28, 1944, No. 7992. Convention date, June 21, 1943. [Class 40 (iv)] Each finder of a set of common first identification finders in a system similar to that described in Specification 592,846 is arranged to stop when it finds any of' a number of potentials applied over the normal switch train to the T-terminal by a wire chief, automatic ticketing equipment, a special service operator, either of two toll operators and a portable test set respectively, the second identification finders associated individually with these services stopping only when they find the potential distinctive of that service. When any of the potentials in question is applied (by keys IK1 or IK2 or relays IR1 ... IR4) to the T-circuit, the relay GSR of the group containing the calling line starts the corresponding first identitication finder which hunts in the ordinary way under control of its test relay TR, which responds to any of the possible markings and energizes a relay AR to extend the marking to the banks of the second identification finders. The finder corresponding to the operated relay IR or key IK is already in motion and stops when its test wiper TB, Fig. 2, encounters the voltage characteristic of the service in question, since in that case no current flows in a pair of vacuum tubes V1, V2 and the resulting rise in voltage allows a gas-filled tube GV to break down and energize GVR. In a modification, Fig. 3 (not shown), the application of a characteristic potential to the T-wire is used also to cause the association of repeaters and ticketing equipment with such calls as need them and to cause the transfer of a call from one operator to another. Rectifiers are provided where necessary to prevent the operation of the finder circuits by metering potential and vice versa. Specification 577,088 also is referred to. The Specification as open to inspection under Sect. 91 comprises also an arrangement whereby the application of characteristic potentials to the T-wire of a jack circuit causes the finder of a junction leading in a desired direction to make connection with the jack. This subject-matter does not appear in the Specification as accepted.