Patent GB-511695-A (GB)
Title: Improvements in electric signalling systems
IPC: H04M15/10
Filed: 1938-02-22
Abstract: 511,695. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd., and WRIGHT, E. P. G. Feb. 22, 1938, No. 5589. [Class 40 (iv)] [Also in Group XL] In an electric signalling system, particularly a, telephone exchange system, information received in a code having a digital significance in the system is translated into a code having an alphabetical significance. The invention may be utilized to obtain a printed record of the name of the exchange, and if desired of the town,' for metering purposes, toll checking, malicious call tracing and fire &c. alarm arrangements where identification of the calling line is required, the translation being derived from exchange digits dialled by a calling subscriber, transmitted by identification equipment or stored in registers. The digits may be transmitted and stored in code; and where a digit or digits have already been used to obtain access to a toll line with which the equipment is associated. the toll line circuit may send an invariable digit or digits to the equipment which may suffice to determine the translation. The translation may be used to control a call announcer. As described, the exchange designation is determined by a single digit stored, together with the numerical designation, in a circuit reached over a finder CH and consisting of groups of 5 condensers from which a positive or negative impulse is received for each digit 'as described in Specification 476,088. When the storage circuit calls for a translation, ground on STL operates start relay ST and CH hunts until TT operates, ST then releasing slowly so that an impulse is sent over chm 7 to the 'storage circuit in response to which the exchange designation is sent as a positive or negative impulse over one of wipers chm 2-6. In the meantime, switch CS has commenced to step and proceeds to a contact dependent on the operation of relays CA ... CE responding to an impulse of either polarity and CF responding to a positive impulse. Assuming that CE operates alone, TS pulls up over csm 4 and ssm 3, stops CS and operates a " town " relay such as LN or BM cross connected over frame TF or a switch to the contact of CS. Relay CR pulls up to ground on a teleprinter lead TPE which is removed and re-applied after each response of the teleprinter, and relays TB, L energize over ssm 2 (normal) and ground all the leads a ... e to the teleprinter TP to effect letter shift. Relay CR releases and re-operates, SSM takes a step, L and TB fall back and ground is applied to the second contact of ssm 2. It will be assumed that " town " relay LN (London) has been operated so that the ground on ssm 2 operates relays B, D of a translating set connected to the contacts of SSM over frame CCF. These relays ground a combination of wires a ... c to cause the printing of letter L. The remaining letters are printed in similar manner during the advance of SSM to contacts 8 whereupon L pulls up to signal a space to the teleprinter and SSM takes another step. Ground is now applied over ssm 2 and csm 1 to a relay of the translating set A .... K determined by the setting of CS where by a combination of leads a ... e is grounded to cause the first letter of the exchange to be printed, the other two letters being printed in similar manner by selections over csm 2 and 3 when SS is in positions 10 and 11. In position 12, the figure shift signal is sent, CE which has been holding over ssm 6 is released, and the storage circuit is signalled over chm 7 to send the first digit of the numerical designation. In position 13 of SS, TS has released to remove control by relay CR, the holding circuits for the digit responding relays CA ... CF now passing over relay CG to ground on teleprinter lead TPE. The code over the teleprinter wires a ... e is now controlled directly by relays CA ... CF in conjunction with CG which relapses and re-operates on each response of the teleprinter to signal the storage circuit after each digit has been printed. Switch SS remains in position 13 until the storage circuit releases TT on termination of the transmission. If the town has only one exchange, the contact of csm 5 is jumpered direct to relay P so that when SS steps to its 2nd position, it proceeds forthwith by selfinterruption to position 9, the exchange (town) letters and the number being then printed as described above. Calculating the price of the call. Relay P which may be operated directly as described above or by the " town " relay such as LN may be used in conjunction with calculating apparatus not shown.