Patent GB-345268-A (GB)
Title: Improvements in impulse repeating arrangements for telephone or like systems
IPC: H04Q1/36
Filed: 1929-12-18
Abstract: 345,268. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd., Columbia House, Aldwych, London. -(GanÚline, C. S.; 18, Rue Boudewyns, Antwerp, Belgium.) Dec. 18, 1929, No. 38781. [Class 40 (iv).] In order to ensure proper transmission of impulses over long subscribers' lines, such lines are associated directly or over non-numerical switches with impulse repeaters having a sensitive impulse relay fed by battery of higher voltage than that supplying the remainder of the system. The normal line relay, which is replaced by the impulse relay before impulse transmission, is also connected to the higher voltage. In one arrangement, Fig. 1, the impulse repeater is individual to the line and gives access to a call finder, while in another arrangement, Fig. 2, long lines are grouped and obtain access to repeaters over auxiliary call finders. In both arrangements, means are provided for repeating ringing from a connector and, in Fig. 2, an auxiliary feed bridge is connected in the incoming speaking path which does not include the repeater. The subscribers with long lines may have a local speaking battery. Repeater individual to subscriber's line, Fig. 1; outgoing call. Relays A, B energize and impulse relay C pulls up in a local circuit to complete the circuit of D which starts the finders. When the calling line is found, CO releases D and operates F which locks up, releases A, B and connects the line through to repeating coil RC. Relay C is very sensitive and battery 1B supplying relays A, C is of greater voltage than the battery serving the remainder of the system. Impulses are repeated at c1 over a loop circuit. Owing to the high resistance of C, battery 1B supplies only a small speaking current for the calling party, and a substation battery may be provided for this purpose. Incoming call. Ground over wiper C1 of the final selector operates CO and ringing current operates G intermittently so that ringing current is connected over g1 to subscriber's line. Relay G is of sufficiently high resistance to prevent the tripping of ringing at the final selector and A does not operate. When the called party replies, A pulls up followed by B, C and F. Relay C completes the loop at c1 to trip ringing at the final selection, while F completes the speaking path to RC and releases A, B, relay G having previously been released by B to disconnect local ringing current. Repeater associated with line by auxiliary call finders; outgoing call. Relays A, B energize, and ground over b2 operates common start relay C which energizes D to complete driving circuits for the auxiliary finders over relay S. When the calling line is found, battery over b2 on the d terminal operates E over its lower high resistance winding which energizes F so that ground over the upper low resistance winding of E short-circuits C which releases D. Relay G operates in a local loop circuit and completes a loop circuit for H which, at h1, starts the regular line finders. When one of these finders reaches the calling line, CO pulls up, releases H, locks F and operates K, the marginal metering relay M remaining inert. Relay K releases A, B, and E, and switches the line through to the repeater Dialled impulses are repeated at g1. Metering. On release of the connection, booster battery operates M which connects battery to meter MR and lights lamp MP. Preventing simultaneous seizure of line by two or more finders. Relays E, F of the finders operate as previously described, but the relays E cannot remain energized in parallel and therefore, with relays F, relapse to reconnect the driving circuits. As the release periods of relays E, F in various finders will be naturally different, the finders will be restarted at different times. All finders busy. There will be no circuit for relay S so that lamp CP glows. Incoming call. When a final selector (a2, b2, c2) seizes the line, N is operated by ground over c2 and prepares circuits for Q. Ringing current over a2 operates O intermittently so that ringing current is connected at o1 to the wanted line, relay A remaining inert. When the wanted party replies, A operates B so that P pulls up to trip local ringing, connects the windings of Q to the line in place of A, so that the line terminals of the final selector are looped over BC whereupon ringing is tripped at the final selector. Fault signals. Lamp MP in the metering circuit will also indicate permanent grounds in the battery distribution system. A faulty finder may be put out of service by key BK.