GB842481A - Improvements relating to multi-channel pulse communication systems - Google Patents

Abstract

842,481. Multiplex pulse signalling. SIEMENS EDISON SWAN Ltd. Nov. 5, 1958 [Nov. 18, 1957], No. 35857/57. Class 40(5). A time division multiplex pulse communication system includes an arrangement for providing conversion from a two-wire to a four-wire circuit to enable amplification to be effected in the "Go" and "Return" paths respectively. The paths may be constituted by coaxial cables or may include radio links. The system is of the type in which terminal stations A, B, C, at one end have access through transistor gate circuits GA, GB, GC, to similar stations at the other end, the gate circuits permitting the passage of signals in either direction and being controlled by respective pulses in the channel pulse cycle. In a known arrangement a gate circuit, for example GA, when opened, allows a capacitor CA previously charged by the input signal to share its charge via the common line with a similar capacitor at a terminal station at the opposite end of the two-wire pulse highway the pulsing of the relevant gate circuits being appropriately timed. In the present arrangement the two-wire line 2W is connected via a gate circuit GS, and unidirectional amplifier AS in the "Go" path of the four-wire section HW, and via a unidirectional amplifier AR and gate circuit GR in the "Return" path. A similar arrangement is included at the other end of the four-wire section. By this means communication is established between say terminal station A and the "Go" path of the four-wire section by applying gating pulses to the send gate GS coincident with channel pulses applied to open the gate GA, thus permitting the potential on the capacitor CA to be applied to the amplifier AS, the high input impedance of the amplifier preventing discharge of the capacitor CA. For communication to be established via the "Return" path, gating pulses displaced in time from those used for the "Go" path of the four-wire section, but again coincident with the channel pulses, are applied to the receive gate GR. Just before the gate GR is opened the capacitor CR is charged through the amplifier AR by an appropriately timed signal pulse transmitted from the far end of the pulse highway, and when the gates GR and GA are opened, the signal is transferred by a chargesharing action between the capacitors and CR and CA. The capacitor CR is then discharged by a pulse applied via diode Rf. In order to increase the number of time channels available, the components GR, CR, HR, may be duplicated as shown in dotted lines and arranged to function alternately.