| 摘要 |
862,270. Automatic exchange systems. STANDARD TELEPHONES & CABLES Ltd. Nov. 8, 1957, No. 34885/57. Class 40 (4). Means for allocating time-positions in a time-division multiplex transmission system to a calling line comprises a co-ordinate array of cells in which each row is allocated to a timeposition. While a time-position is not in use the associated row is arranged to store a number which is cyclically varied according to the numbers of the lines, variation of the number ceasing when a calling line is encountered. The co-ordinate array makes up a store and may be arranged as a coordinate arrangement of toroids, a perforated ferrite plate, or a number of columns of delay lines or stepping pattern registers. The store has a row of storage cells for each time-position in a 100-division multiplex system. Each row has two groups of digit cells 1-5 and 6-10 and a group of three control cells. The rows are read one by one in a recurring cycle under the control of a pulse generator and distributer. Assume a number 9 has been read from a row and there is no entry in the control cells (read cycle 1, Fig. 10). This number energizes the appropriate column circuits in the group 1-10, Fig. 1. Unity is added by the control gates so that the number 10 is recorded in the digit cells together with an entry a in the control cells. When the row is scanned for the second time the numbers 10 and a are read. The entry a enables the access gates so that the digits 1 and 0 operate a cell in a co-ordinately-arranged access selector whereby a pulse is delivered to a test gate GT10, of the type described in Specification 824,222 associated with the line 10. If the line is idle no pulse P is delivered and the number 10 is rerecorded with no entry in the control cells. When the row is scanned for the third time the number 11 is entered together with entry a in the control cells. The process continues with the time-position represented by the row being effered to all lines in turn during alternate cycles. If, however, the line 10 is engaged when tested in the second cycle the associated test gate GT10 delivers a pulse P which operates the control gates of Fig. 1 so that the same number 10 is re-recorded with a different entry b in the control cells. These entries are re-recorded at each scan until a comparator is available and receives the digit 10. The entry b is then replaced by c. During one complete cycle the number 10 is compared with the numbers read out from the other rows whose time-positions have been allocated. If identity is found the comparator (Figs. 7 and 8, not shown) is released and the time-position is offered to other lines. If the cycle is completed without identity being found the comparator is released and entry c is replaced by d. The entries 10 and d are then read and re-recorded for the duration of the call on the line 10. Specification 862,271 also is referred to.
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