Patent GB-1052827-A (GB)
IPC: H04J3/20
Abstract: 1,052,827. Automatic exchange systems; pulse modulation systems. SIEMENS & HALSKE A.G. April 29, 1964 [April 29. 1963]. No. 17762/64. Headings H4K and H4L. In a time division multiplex exchange utilizing the resonant transfer method of signalling, an intermediate store and rectifier are connected to the multiplex highway whereby when a line store is connected to the highway during a relevant time slot, energy stored in the line store is transferred to the intermediate store as a half-wave oscillation, the closing time of the switch which completes the path between the stores being less than the periodic time t1 of the resonant circuit thus completed and greater than ¢t1. The closing time of the line and intermediate switches and the adjustment of the resonant circuits are rendered non- critical by these means. In the systems shown, the intermediate stores S1, S2 may each comprise a single capacitor provided with a short circuiting contact (Fig. 3, not shown), a magnetic core provided with read-out and reset windings (Fig. 4, not shown) or a capacitor bridge (Fig. 5, not shown) which forms part of a parametric amplifier. The necessary inductance for tuning the circuits may be provided by an individual inductor at each of the line circuits, e.g. inductor La or by a single inductance (lumped or distributed) located in the highway. The line stores (capacitors Ca, Cb) are positively biased by sources +U and the rectifiers G ensure that only half-wave oscillations are transmitted. In operation, switch ta is closed for the duration of a first time slot and, concurrently therewith, switch 1k1 is closed but for a period preferably less than half that of ta. Energy, in Ca, is transferred to S1 while 1k1 is closed, as a half-wave oscillation, because of the action of rectifier G1 and the fact that 1k1 is closed for a period less than the periodic time of the resonant circuit formed by Ca, La and S1. During the remaining portion of this time slot, store S2 is cleared of any information it may have retained from a previous operation. Switch tb is closed in the next time slot during the first half of which store Cb is connected to S2 via 1k2 and during the second half of which S1 is connected to Cb via 2k1. Finally ta is again closed during the third time slot whereby store S1 is cleared and store S2 is connected to Ca via 2k2. In the system shown in Fig. 2 an outgoing (calling) highway Mab and an incoming (called) highway Man is used. Here, calling store Ca is connected via abta and 1k1 to S1 and called store Cb is connected via antb and 2k2 to S2 during a first time slot and store S1 is then connected via 2k1 and antb to Cb and store S2 is connected via 1k2 and abta to Ca during the next time slot. The stores S1 and S2 are cleared prior to each pair of time slots used for the exchange of signals between two line stores. If diode or similar unidirectional switches are used for the switches 1k and 2k, the separate rectifiers G may be dispensed with. In copending Specification 1,052,828 (Division H3) which is generally similar to the present Specification, the use of a superconducting device as the intermediate store is mentioned.