GB1107067A - Improvements in or relating to telecommunications exchange systems - Google Patents

Abstract

1,107,067. Data transmission systems. SIEMENS A.G. 27 July, 1966 [28 July, 1965], No. 33763/66. Heading H4P. In an exchange system in which each subscriber is connected to a multiple line and transmits or receives each bit on a combination of channels in said line which is unique to the calling or called subscriber, dialling and control signals are transmitted on the same combination of channels but are distinguished from the binary data by modification by a preset signal. To call the exchange a subscriber pulses his combination transmitter at the exchange. This energizes a unique combination of channels and also two additional channels. The latter cause a free connector set to be seized and causes the unique combination to be stored and a monostable unit to be triggered. When now a call-up pulse arrives at the connector set, gating means pulse a combination of channels identical to that stored. This pulse therefore passes to the calling subscriber's combination receiver. A pulse is also passed over the additional channels to that receiver. A further pulse passes over all these channels when the monostable unit resets. In response to the pulses the combination receiver indicates to the calling subscriber that the exchange is ready to receive dialling pulses. The dialling pulses pass on the calling subscriber's unique combination, together with pulses on one of the additional channels, through gating units to a counter which generates a signal on a combination of channels representing the called station. This signal is used to set the combination transmitter of the calling station to the combination representing the called station, or the receiver of the called station to that representing the calling station. In an alternative arrangement the two additional channels are not used. Instead the combination from the calling subscriber is modified by a preset signal and the modified signal is repeated a number of times. A counter counts these repeated signals to determine what signal is meant.