Patent GB-548838-A (GB)
Title: Telephone systems
IPC: H04Q3/42
Filed: 1941-06-06
Abstract: 548,838. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd. (Western Electric Co., Inc.). June 6, 1941, No. 7170. [Class 40 (iv)] [Also in Group XXXVII] In a register-controller, the wanted number is recorded magnetically on a tape or other medium and is subsequently reproduced for setting up the connection. When the subscribers are provided with ordinary dials, Figs. 4-7 (not shown), the impulses of the successive digits are recorded as a series of magnetized areas which as the tape passes through an air-gap affect the flux in a magnetic circuit controlling a pair -of contacts in an outgoing impulse circuit. A single tape may be used for all the digits or there may be one tape for each digit. The subscribers may be provided instead with reed transmitters of the kind described in Specification 538,552 which send a combination of frequencies for each digit, and it is then necessary for the reproduced designation to be translated into numerical form at some stage. In the cross-bar system shown in Figs. 1-3, as soon as the sender is seized, the tape 208 is fed from a container 209 through. the recorder 207 to a container 212 and thence through the reproducer 215. The reproduced office digits go to a translator 300 comprising a number of filters in parallel and a marker 321 is taken into use to control the extension of the connection through district and office switches S, S1 to the required exchange or to the local switches. The feed to the reproducer 215 is temporarily stopped by means of relay 323 until an incoming sender 103 or 108 is seized, whereupon the remaining digits are transferred thereto, relay 301 being operative, and translated into numerical form by means of filters to control the completion of the connection with the help of a marker. The feed to the reproducer is started by the arrival of signals, and therefore if no signals are received. all the tape is eventually withdrawn from the container 209, and the closure of contacts .217 operates relay 326 which causes the call to be routed to an operator's position. Moreover the feed to the reproducer is slower than that to the recorder, so that the tape in the container 209 eventually becomes exhausted with a similar result if the sender is held for an abnormal time. During the release of the sender the feed through the reproducer is continued until all the tape is withdrawn from the container 212, when contacts 219 make a circuit for relay 236. In a modified system, Figs. 8-12 (not shown), the office digits are reproduced at a high speed and delivered in code form to a marker which controls routing and in addition determines how the numerical digits are to be sent. If the wanted exchange is of cross-bar type they are sent in code to an incoming sender thereat as described above, but if it is of step-by-step or panel type a decoder is taken into use in order to set numerical registers which then control the completion of the connection by direct or revertive impulsing. The reproduction of the numerical digits takes place at a low speed. Alternatively the numerical digits may be sent in code in all cases, and a decoder may be used when necessary at the terminating exchange. Specifications 466,986 and 522,798, [Group XXXVII], also are referred to.