Patent GB-977420-A (GB)
Title: Control system for communication network
IPC: H03K17/16
Filed: 1961-07-21
Abstract: 977,420. Automatic exchange systems. STANDARD TELEPHONES & CABLES Ltd. July 21, 1961 [July 28, 1960], No. 26543/61. Heading H4K. A slow-speed serial access register, each compartment of which contains information governing the connection of two subscribers in a system having a plurality of time division multiplex highways, is cycled over its compartments at a speed such that the contents of each compartment are staticized for an interval at least as long as a multiplex cycle so that the information may be transferred to high-speed slave registers associated with each multiplex highway. Each highway of the system serves 100 subscribers and provides 25 channels in a multiplex cycle of 100 microseconds. Connections between different highways are made with the same time slot coincident in both highways and in an intermediate highway linking the other two. Transmission may be over both way resonant transfer gates. Connections between subscribers served by the same highway are made with two time slots and an intermediately connected storage device. The 100 gates, such as G 00 , connecting subscribers to a multiplex highway, are controlled by a high-speed slave register SM, similar registers being provided to control gating to intermediate highways. The gates are switched at the appropriate channel times by the elements, such as X 00 , of a 10 x 10 matrix shown in Fig. 3, the matrix being marked on a row and column wire according to the tens and units digit of the subscriber being connected. A subscriber's tens and units digits are set up in the slave register as 2-out-of-5 codes in two sets of five recirculating magneto-strictive delay line stores, one of which is shown in Fig. 3 at DSM. In each channel time the contents of the circulating stores is set up on two sets of five bistable circuits, one of which is shown at BS, and the markings extended by the bi-stable circuits are decoded to provide 1-out-of-10 markings by circuits DCT, DCU, to mark the 10 x 10 channel gate switching matrix. A recirculating delay line store is shown in Fig. 4 and is controlled by 1 microsecond pulses TW1 at the end of each channel time of 4 microseconds and by 2 microsecond pulses TW2 occurring at the beginning of each channel time. The delay line normally circulates pulses at 4 microsecond intervals which over gate G12 sets by-stable circuit BS to its O state for the appropriate channel time. With BS in a O state gate G14 is normally open to enable gate G15 which passes a TW2 pulse to regenerate the pulse in the delay line DL by means of a blocking oscillator MS. So long as a pulse circulates the bi-stable circuit BS is set to its O state in the corresponding channel time. The master control equipment injects information into a set of five delay line stores DSM by means of a thousands and hundreds mark on gates such as G10 and inverters 12. Input to inverter 12 disables gate G14 and prevents regeneration of a pulse circulating in the time slot. If gate G10 has a tens or units mark then G15 is enabled to restore the pulse in circulation. In the absence of a tens or units mark to gate G10 no pulse is circulated in the time slot and, whenever this time slot occurs, inverter I1 enables G13 to set bi-stable circuit BS to its 1 state which extends a mark to the multiplex gate switching matrix. As shown in Fig. 1 a slow-speed serial access register MM is cycled over 1080 compartments with a period of 129.6 milliseconds. In each compartment time of 120 microseconds ten microseconds is spent in reading the information from the compartment to a staticizer MST, ten periods of ten microseconds are spent in performing unspecified logical operations on the data set up in the staticizer, and the final ten microseconds is occupied with returning the information to the register MM. The manner in which information is registered in MM is not described but the information is said to comprise five elements SO which control signalling between the staticizer MST and the high-speed slave registers; four sets of five elements SGG, GG, TG, UG, which identify the calling subscriber with a 2-out-of-5 code in each set; four sets of five elements SGD, GD, TD, UD, which identify the called subscriber similarly; and two sets of seven elements CHG, CHD, recording in 3-out-of-7 code the channel position of the calling and called subscribers, respectively. Each cell of the staticizer is associated with a gate, only gates G2 to G7 being shown as examples, and depending on the state of cells. SO the calling or the called line information is passed by the gates for routing to the appropriate highway gates. The 2-out-of- 5 codes giving the tens and units digits are connected in multiple over mixer gates, such as M5, M6, to the 100 high-speed slave registers SM described above. The thousands and hundreds digits are translated from their 2-outof-5 codes to one-out-of-ten markings by decoders DCS, DCG, and by enabling one of ten group gates, of which G8 is an example, and one of a hundred second stage gates, of which G9 is an example, the ten gates, of which only G10 and G11 are shown, of the appropriate high-speed register are enabled in the time slot of the calling or called subscriber. The generation of a pulse in the right time slot is effected by a comparator CMP to which the channel time slots are presented in sequence by 3-out-of-7 markings on terminals P1 to P7. The staticizer MST presents its information for the whole of a multiplex cycle of 100 microseconds and when the code set up in cells CHG, or CHD, finds a match in the comparator CMP, the desired time slot is signalled over the thousands and hundreds gates to gate the information presented by the staticizer to the slave register SM as described above. By this means the slave register is brought up to date once in every 1,296 multiplex cycles as regards its connection of a single multiplex highway gate. A transistor circuit is described which may be employed as the comparator CMP, see Fig. 7, not shown. A check may be put on the function of CMP by providing a second but complementary comparator for fear that an erroneous 4- or 5-out-of- 7 code may arise which would cause widespread blocking of highway channels. Specifications 765,681, 824,222, 904,232, 904,233 and 971,763 are referred to