GB1022990A - System for reception of electric signals applicable mainly to telegraph exchanges - Google Patents

Abstract

1,022,990. Telegraphy. STANDARD TELEPHONES & CABLES Ltd. Nov. 20, 1964 [Nov. 20, 1963], No. 47313/64. Heading H4P. The invention provides a repeater which is used in time-multiplex manner with a plurality of lines, and a record queue is made of the time of occurrence of each transition in the received data, the regenerated signals being derived from queue. In the embodiment described the incoming lines are scanned in groups of seven lines. All the groups are scanned during a bit period, and each line is scanned several times in each bit period. Input cycle for each line relay contact group selected. Any data currently stored in the row of a core store MG corresponding to the group selected is transferred to a register RM, and the data read from the relay contacts is stored in a register RE and also in store MG. At this point, therefore, the current state of the incoming lines of the selected group is stored in RE and the state during the preceding scan of that group is in RM. The present and past states of the line group are compared, and any change in state is stored in RE. A counter which indicates the first available position in the queue store causes a scanner to select that position, and the line group number, the transition indications, and the time of occurrence of the transition (in binary code and relative to the start bit) are stored therein. The queue counter advances one step and the cycle repeats for the next selected group. Output cycle.-This cycle takes place only if the queue store indicates that a change in data state has occurred. A queue counter indicates the position in the queue which is to be read first. When that position has been selected, the data from the queue is passed to store RA. The line group position in a store is selected in accordance with the group number read from the queue, and the position within that group which corresponds to the first line for which a change of state was recorded is chosen. In this position is found a number indieating the time of occurrence of the midpoint of the start bit. The difference between this time and the time of the change of state already stored on RA is determined. If the difference indicates that the change of state corresponds to the second bit in the character then that bit must be a mark since the first or start bit is a space. This bit state is passed to the relevant line store. The process then repeats for each line in the group, whereupon the queue counter is stepped and the whole cycle repeats for the next queue location. When a complete character has been reconstituted it, together with the appropriate line number, is stored in another queue store prior to processing by known means.