Patent GB-872059-A (GB)
Title: Concentrators of telephone lines or the like
IPC: H04Q3/58
Filed: 1957-12-31
Abstract: 872,059. Automatic exchange systems. STANDARD TELEPHONES & CABLES Ltd. (Compagnie Generale de Constructions Telephoniques S.A., and Materiel Telephonique S.A.). Dec. 31, 1957, No. 40380/57. Class 40 (4). In a system including an automatic satellite (non-exchange) having cross-bar switches at the satellite and at the exchange for connecting the subscribers' lines and their exchange appearances, respectively, to a group of trunks smaller in number than the subscribers, test devices are provided, one at the satellite and one at the exchange, each of which consists of a plurality of rectifier and relay matrices, which devices respond to calls originated by the subscribers and by the exchange appearances, respectively, to operate a combination of relays indicative of the calling line or appearance, the operated relays causing the transmission of a signal indicating the existence of a call. In the first embodiment (Fig. 1, not shown) fifty subscribers can be associated with their respective exchange appearances by way of eight bothway trunks, over cross-bar switches in a subscriber's-end concentrator "A" and an exchange-end concentrator " B." The test devices respond to calls, each choosing one call if more than one occur simultaneously and operating relays to identify the calling subscriber or exchange appearance in code form. Each then signals to an option device in concentrator " B " the existence of a call, the option device giving preference to outgoing calls from the exchange signalled by " B." The option device having chosen the call to be dealt with, causes the transmission of code signals to operate the relays of a set of selecting relays in each concentrator in accordance with the identity of the line or appearance concerned, the relays thus operated energizing the relevant cross-bar magnets to complete the connection over a free trunk. Operation.-The cross-bar switches used each have 13 selecting bars movable in either of two directions by 26 selecting magnets, an auxiliary bar with two magnets serving for double group working, so that any one of 52 lines (or appearances) can, by way of the relevant one of 8 hold magnets, be connected to any one of the eight trunks. The fifty-two lines (or appearances) are divided into four groups I to IV the test wires of which are connected to the four inputs of a rectifier and relay matrix A, in the test device (Fig. 4), leading to the four relays aa 1-4, respectively; the identification of a line within its group being effected by the 5-input matrix B and the 6-input matrix C which operate two of the six relays ad in each case. Incoming call.-Assuming lines 4, 17, 18 and 39 to be calling, relays aa<SP>1</SP>, aa<SP>2</SP> and aa<SP>3</SP> are all energized at "A " and each short-circuits the others. They all release and re-operate until eventually one, say aa<SP>2</SP>, succeeds in holding, and short-circuits the others. Relay aa<SP>2</SP> operates coding relay ab<SP>2</SP> which connects ground to matrix B. The test wires of groups I, III and IV are grounded by aa<SP>2</SP>, but the lines 17 and 18 are still effective upon matrix B to operate ac<SP>2</SP>, which brings up coding relay ad<SP>2</SP>, and also grounds the test wires of lines 1 to 3, and 7 to 13 of each group. Lines 17 and 18 (4 and 5 of the second group) operate ae<SP>3</SP> and ae<SP>4</SP>, which release and re-operate until one, say ae<SP>3</SP>, holds and brings up coding relay ad<SP>3</SP>. The operated combination of coding relays ab<SP>2</SP>, ad<SP>2</SP> and ad<SP>3</SP> identifies the calling line as No. 17. At the concentrator "A," the operation of the ad relays completes a loop over the signalling pair ta<SP>1</SP>, tb<SP>1</SP> (Fig. 5) to the concentrator " B." Providing no outgoing call is waiting (dh down), the concentrator " B " applies the positive pole of battery 66 to ta<SP>1</SP> and the negative pole to tb<SP>1</SP> (Fig. 6), so that da pulls up to this incoming call signal and operates the incoming option relay db<SP>2</SP> (Fig. 7) which cuts off the outgoing option relay db<SP>1</SP> and relay dh. Relay da brings up the slow-torelease df which holds da after the operation of cj, as mentioned below. Relay da also starts a pulse generator (Fig. 7) by operating the slowto-release dc<SP>1</SP>, whereafter dc<SP>1</SP> and dc<SP>2</SP> interact. Alternate operations of dc<SP>1</SP> operate and release dd<SP>1</SP> which sends alternate positive and negative pulses over the pulsing pair ta, tb to "A," and at the same time alternately grounds the odd and even relays of the stepping chain cf<SP>1</SP>-cf<SP>4</SP>, ch<SP>1</SP>-ch<SP>6</SP>, cj at " B " (Fig. 6). This chain and the corresponding one af<SP>1</SP>-af<SP>4</SP>, ah<SP>1</SP>-ah<SP>6</SP>, aj at "A" (Fig. 5) are thus stepped synchronously. At each step the chain at "A" connects across the pair ta<SP>1</SP>-tb<SP>1</SP> the relevant one of the selecting relays ag<SP>1</SP>-ag<SP>1</SP>, ai<SP>1</SP>-ai<SP>6</SP>in series with a make contact of one or more of the coding relays ab<SP>1</SP>-ab<SP>4</SP>, ad<SP>1</SP>-ad<SP>6</SP>, while the chain at "B" includes in the loop of ta<SP>1</SP>-tb<SP>1</SP> the corresponding one of the selecting relays cg<SP>1</SP>-cg<SP>4</SP>, ci<SP>1</SP>-ci<SP>6</SP>. Consequently, two of the relays ag<SP>1</SP>-ag<SP>4</SP> and two of the relays ai<SP>1</SP>-ai<SP>4</SP> are operated together with the corresponding relays of eg<SP>1</SP>-cg<SP>4</SP> and ci<SP>1</SP>-ci<SP>6</SP>. In the case of line No. 17 calling these are ag<SP>1</SP>, ag<SP>4</SP>, ai<SP>2</SP> and ai<SP>3</SP>, cg<SP>1</SP>, cg<SP>4</SP>, ci<SP>2</SP> and ci<SP>3</SP>. When aj and cj operate at the end of the stepping, the latter relay holds dc<SP>1</SP> (Fig. 7) which maintains dd<SP>1</SP> operated under control of da. The operation of da also brings up the seizing relays ja (Fig. 8) of all free trunks, that of the first jaN) locking up with dj and bringing up the corresponding auxiliary relay jmN which extends battery over the "a" wire of the selected trunk N (Fig. 10) to operate the corresponding seizing relay amN (Fig. 9) at concentrator "A." In the case of an incoming call, jmN also brings up jcN (Fig. 10) over front db<SP>2</SP>. The double group working select magnet SX<SP>1</SP> at " A " operates under control of ag<SP>1</SP>, and the select magnet SS17 under control of ag<SP>4</SP>, ai<SP>2</SP> and ai<SP>3</SP>, similar operations taking place at " B." At " B " relay ck (Fig. 6) now pulls up over front contacts of the select magnets, and dg (Fig. 7) follows. Relay ck operates the hold magnet VN (Fig. 10) selected by jmN, which holds in series with jnN; and also applies positive battery to the " b " wire of the selected trunk. This, in conjunction with the negative battery on the " a " wire, operates the corresponding hold magnet VN (Fig. 9) at "A." The cross-bar switches are thus operated. At " B " operation of the hold magnets VN at "A" and " B " releases ck (Fig. 6), whereupon da falls away releasing the operated relays of Figs. 5, 6 and 7 and the select magnets at "A" and " B." If the cross-bar switches had not been operated in the normal period, the release of df which follows the operation of ck would have released da, thus cancelling the operations thus far performed. With the crossbar switch at " B " operated the cut-off relay cx<SP>17</SP> (Fig. 10) is operated over the d wire thus busying the exchange appearance of line No. 17, and with jcN up (incoming call) a local loop is extended to the exchange to operate the line relay lr (Fig. 11) which starts the exchange switches hunting for the call. At "A" the cutoff relay ax<SP>17</SP> (Fig. 9) operates in the hold magnet locking circuit. The release of jmN (Fig. 8), which follows that of da, causes the application of ground to the " a " wire of the trunk (Fig. 10), and of battery via jcN to the " b " wire, whereupon amN (Fig. 9) is released by shortcircuit and the trunk is extended to the caller, jcN holding to his loop while the exchange hunts for the call. On finding, ground on the "c" wire (Fig. 10) brings up jbN which switches through, jcN releases, and jbN holds VN at " B." Release is initiated by the removal of the " c " wire ground by the exchange, the release of the hold magnet at " B " bringing up releasing relay anN (Fig. 9) at " A " to release the hold magnet thereat. Outgoing call.-The identity of the calling exchange appearance, indicated by the grounding of its " c " wire, is coded by the test device at " B " in the same manner as was that of a calling line by that at "A," the battery and ground connections in Fig. 4 being interchanged in the device at " B " and the rectifiers being reversed. Providing no incoming call is being handled, i.e. ab<SP>2</SP> back, operation of a coding relay cb<SP>1-4</SP> at " B " brings up relay dh (Fig. 7) which reverses the battery connections to ta<SP>1</SP>-tb<SP>1</SP>, connecting positive to tb<SP>1</SP>. If all the select magnets are in their unoperated condition relay da operates in the loop and brings up the outgoing option relay db1 which connects the positive pole of the code-sending battery 68 to wire tb<SP>1</SP> and its negative pole to the selecting relays cg<SP>1-4</SP> and ci<SP>1-6</SP>. The pulse generator is started as before and the stepping chains at " A " and " B " are operated in synchronism. Selecting relays at "A " and " B " are energized in accordance with the coding relays which have been operated at " B " to record the identity of the calling appearance. A free trunk is seized and the cross-bar switches are operated as for an incoming call, whereafter jbN (Fig. 10) operates immediately to the grounded "c" wire of the calling appearance to switch through. Second embodiment, in which the coding relays also act as selecting relays.-The satellite (non- exchange) serves 48 lines, each test device (Fig. 12) having a 4-input matrix B i