US2106897A - Automatic or semiautomatic telephone system - Google Patents

Automatic or semiautomatic telephone system Download PDF

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Publication number
US2106897A
US2106897A US5735A US573535A US2106897A US 2106897 A US2106897 A US 2106897A US 5735 A US5735 A US 5735A US 573535 A US573535 A US 573535A US 2106897 A US2106897 A US 2106897A
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group
switch
selector
relay
lines
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US5735A
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Mercer Richard
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Associated Electric Laboratories Inc
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Associated Electric Laboratories Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/42—Circuit arrangements for indirect selecting controlled by common circuits, e.g. register controller, marker
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/0016—Arrangements providing connection between exchanges

Definitions

  • the present invention concerns improvements in or relating to automatic or semi-automatic telephone systems.
  • a particular object of the invention is to effect economies in such systems by ensuring that the bank contacts of some, if not all, of the switches employed in such systems are used more eiciently.
  • the invention is characterized by the provision of two switches adapted to Work in combination during the setting up of a connection.
  • One switch over which the connection will be set up will be referred to as a selector switch and the other switch, which need only be used temporarily, will be referred to as an auxiliary switch.
  • the auxiliary switch differs from the selector switch in that it is either of a different type of construction or it has a diierent form of control, or it may have both a diierent type of construction and a different type of control, the auxiliary switch and the selector switch being arranged to have access to the same line or lines, or at least to the test contacts of the same line or lines, but one switch is arranged to have access to lines to which the other switch does not have access, the arrangement being such that when it is determined that the connection is to be set up over a line to which both switches have access the auxiliary switch which is first caused to select such line is arranged to control the establishment of the connection via the selector switch and the line determined by the setting of the auxiliary switch.
  • auxiliary switch may differ from the selector switch, the following examples are given:
  • the selector switch and the auxiliary switch may have their operations initiated at diierent times, for instance, the auxiliary switch need not be taken into use until after the operation of the selector switch has been initiated and in certain cases when the taking into use of the auxiliary switch is dependent upon whether a certain line or lines are available or not for completing a connection the auxiliary switch may not be required at all.
  • 'I'he selector switch may be of the up-andaround -type having access to 100 contacts or multiples thereof, while the auxiliary switch may be of the uni-selector type having motion in only a single direction or vice versa.
  • the selector switch may be of the crossbar type and the auxiliary switch of the uniselector lor up-and-around type and vice versa.
  • the selector switch and the auxiliary switch may be of the same type but one could be arranged to respond to impulses from a distance and the other could be arranged to hunt automatically.
  • the invention is intended to avoid covering the case of a selector switch and an auxiliary switch being of the same type and controlled in the same way, as it will be evident having regard to the applications of the 10 invention referred to hereinafter that such a combination covers a very restricted field.
  • the invention may be applied to a group selector to enable the groups of lines to which such group selector has access to be varied in size independently of its construction or manner of operation, and for this purpose the auxiliary switch is arranged to have access only to those lines or test contacts of those lines to which the group selector has access and which cannot be selected by the normal operation of v the group selector, said auxiliary switch which is lirst operated to select such a line being further arranged in the event of all lines in the group which can be selected by the normal control of the selector being busy to set up the connection via the group selector to the line determined by the setting of the auxiliary switch.
  • the groups of lines can be made of larger size than the capacity of a level and for this purpose the auxiliary switch takes the form of a hunting switch arranged both to hunt for a particular group as well as to hunt for an idle line in the group and conveniently can take the form of a switch having movement in a single direction only.
  • the auxiliary switch is arranged to have access only to those contacts of a group which are not located in the row or level normally allocated to that group and is arranged to be used in the event of all the lines in the level allocated to the group required being busy to establish an overflow connection and to control the setting of the selector switch on to a contact in another row to which the line selected by the auxiliary switch is also connected. It will be clear that the auxiliary switch only requires to be used for calls to a group of lines which is larger than the normal capacity of a row or level and that it can be entirely dissociated from the switch once the selector switch has itself established a through connection, whether on its original operation or after it has been reset.
  • the invention may be applied to a final selector, whether one having access to single subscribers lines only or one having access to groups of P. B. X. lines, or one having access both to single lines and to P. B. X. lines, and according to this feature of the invention it is possible to allow any subscriber whatever his number to have an additional line as long as there is a vacant contact anywhere onV the switch.
  • the selector switch may be a nal selector of any type whatever, while the auxiliary switch takes the form of a switch having access to those lines or test contacts of those lines which cannot be reached by the normal operation of the final selector, which auxiliary switch after being first controlled to select an idle line of the particular subscriber required is arranged if it is determined that the connection is to be set up over a line to which both the auxiliary switch and the final selector switch have access to control the operation of the final selector so as to set it on to the line determined by the setting of the auxiliary switch.
  • auxiliary switch obviously need only be operatedwhen connection is required to a subscriber having additional lines not directly accessible in response to the dialling of his number and then only if the line or lines reached by the original setting of the selector switch are busy.
  • the function of the auxiliary switch in the event of there being no line free which can be reached by the j original operation of the final selector switch, is
  • nal selector switch to be set on to contacts to which the line found by the auxiliary switch is connected.
  • the inventionv may be applied to alternative routing, that is to say, to arrangements in which a connection can be set up over a more direct route in normal conditions and only when such connections are impossible can it .be set up over a more indirect route.
  • alterna- .tive routing takes the form of routing between exchanges, that is to say, calls from one exchange to another may be normally set up over a direct junctionbetween such exchanges but if all the direct junctions between such exchanges are busy then the connection can be set up via a tandem exchange.
  • the selector switch could take the form of a group: selector having access to direct junction lines leadingto various exchanges and also to lines leading to a tandem exchange, while the auxiliary switch could be arranged to have access only to lines leading to a tandem exchange.
  • the auxiliary switch in this case selects an idle line to the tandem exchange so as to enable switches at the tandem exchange to be operated at the same time as the selector switch is operated.
  • the auxiliary switch if the connection is to be sent via the tandem exchange then controls the selector switch to establish connection to the line which it has previously selected.
  • the invention may be applied to effecting a considerable reduction in the number of switches required in the main train, for instance, the number of second group selectors in a ten-thousand line exchange may be reduced to a very low figure.
  • the selector switch is arranged to have access both to second group selectors and to final selectors, while the auxiliary switch has access to final selectors only. If the auxiliary switch iinds an idle final selector switch in the group determined by the operation of the selector switch and the second group selectoi switch it has selected, then the connection is set up directly between the selector switch and the final selector switch and the second selectorI is cut out.
  • this feature is equally applica-v ble to iirst, second and third selectors, or in fact to selectors of three successive stages.
  • the invention may be applied to employing small capacity switches so that the selector switch takes the form of a small capacity switch, for instance, a twenty-v'e line uni-selector switch, while the auxiliary switch is of a much larger capacity, for instance, an up-andaround switch of line capacity.
  • a small capacity switch for instance, a twenty-v'e line uni-selector switch
  • the auxiliary switch is of a much larger capacity, for instance, an up-andaround switch of line capacity.
  • tor switch has vaccess to the usual numberof groups of lines but these groups will all be of.1 small capacity. If there is an idle line in the ⁇ group required, then the connection will be set up as regards each stage except possibly the nal selector stage over a small capacity switch. If there is no idle line available then the selector switch will select an idle switch, preferably one of large capacity similar to the auxiliary switch,
  • the auxiliary switch will causek such selected switch to be stepped on to contacts previously found by the auxiliary switch so that the connection to the next group stage includes both the selector switch and a large capacity switch. As the large majority of connections will be set up over small capacity switches the number of large capacity switches required will be comparatively small.
  • Fig. 3 showing a busy tone set connected to vacant contacts at the end of a group
  • Figl an cverow link which is common to agroup of selectors including that shown in Fig. l.
  • Figs. 5, 6, and '7 show the application of the invention to a P. B. X. final selector
  • Fig. 5 showing a known P. B. X. final selector circuit with slight modifications
  • Fig. 6 showing themanner of marking the groups of lines
  • Fig. 7 an overow link which is common to a group of selectors including that shown in Fig. 5.
  • Fig. 8 shows a telephone network including exchanges A, B, and T with arrangements for alternative routing so that although calls from exchange A to exchange B are preferably set up over direct junctions from A to B they may be set up over indirect junctions extending via exchange T when all the direct junctions are busy.
  • Fig. 9 shows a switching arrangement whereby calls may in certain circumstances be set up over less than the normal number of switching stages andv Fig. 10 shows an arrangement whereby calls may in certain circumstances be set up over the normal number of switching stages but in which the switches have a capacity of considerably less than a hundred lines.
  • Figs. l, 2, 3, and 4 the invention -is shown applied in a diagrammatic manner to an up-and-around switch arranged to vact as a group selector. It is assumed that the group selector in question is to have access to ten different groups. of lines and that the traflio on the diierent groups varies considerably so that the following distribution of lines is that which appears most advantageous to employ, namely Group Lines 1st 6 '7th 7 8th 18 I n Fig. 2 the manner in which the lines of each group are associated with the various contact sets is illustrated. The niunbers over' the small circuits, each of which represents a contact set, indicate the number of the group to which the contact set belongs.
  • the six lines of group 1 are arranged on the first six contacts of the first level.
  • the rst ten lines of group 2 are arranged on the second level and of the remaining eight lines of group 2, three are shown by way-of example connected to the last three lines of the rst level and ve are shown connected to the last ve lines of the third level.
  • the four lines of group 3 are arranged on the first four contacts of the third level.
  • the eight lines of group 4 are arranged on the first eight contacts of the fourth level.
  • the fifteen lines of group 5 are arranged with ten on the 5th level, one on the fourth level, four on the 6th level. The manner in which the lines in the 6th, 7th, 8th, 9th and 10th groups are arranged will likewise be readily seen from Fig. 3.
  • the general principles of operation of the group selector are as follows. Whenever the group selector is operated to a particular level and there is an idle line in the group corresponding to the level selected then the call is set up in a perfectly straightforward manner following any known method or anyinethod which may be evolved equivalent to the methods at present known. If
  • the oper-v ation depends upon whether the group is a small group 0r a large group, i. e., whether the group occupies less than one level or more than one level.
  • the group occupies less than one level then special arrangements must be provided for preventing the switch hunting past that group of contacts into another group which may bellocated at the end of the level and selecting an idle line in that group. This may be done by providing a vacant contact to which a busy tone set, as illustrated in Fig. 3, may be connected or it may be effected by arranging that the test contacts of the lines not belonging to the group being tested are momentarily rendered busy or it may be effected by arranging to connect the test wiper circuit permanently to busy potential whenever all the lines of the group being tested are busy.
  • auxiliary switch SW2 (Fig. 4) associated with the group selector GS. This may be taken into use only when all the contacts in the level selected in response to the dialled impulses are busy, or it may be taken into use whenever the level selected in response to the dialled impulses forms only part of the complete group of lines; in the embodiment to be described later the second alternative is used but is made dependent upon the initial line or lines in the group being busy.
  • the switch SW2 When taken into use the switch SW2 hunts over those lines of the group required which are located in a different level or levels from the rst choice lines; the switch SW2 has therefore to hunt both for the required group and for an idle line in that group. Only if all the first choice lines, i. e., the lines in the level dialled, are busy, is it necessary to make use of the switch SW2, in which case it establishes a circuit to an idle line in the group required, whereupon the group selector GS is released and reset on to the line selected by the switch SW2.
  • the switch SW2 is connected to the selector GS by means of switch SWl; the circuit including the switches SWI, SW2 will hereinafter be referred to as an overi'iow link.
  • the digit 2 will be dialled and after the switch GS has responded to the two impulses the overflow link SWE, SW2 will be taken into use and while the switch GS is hunting for an idle line on the second level, the switch SW2 will hunt for an idle line among later choices which are connected to contacts on the first and third levels.
  • relay 'A When the first series of impulses is dialled, relay 'A releases intermittently thereby repeating the impulses by way of armatures 29, I8 to relay C in series with the vertical magnet V.
  • the vertical magnet steps the switch wipers to the level corresponding to the digit received whilst relai7 C operates on the rst impulse and remains operated until shortly after the end of the last impulse.
  • Relay 'G operates and completes a locking circuit for itself at armature 24.
  • relay C Shortly after the end of the vlast impulse, relay C releases and completes a circuit for the rotary magnet R over armature ZILsprings controlled by armature 23, and armature 25.
  • the rotary magnet steps the switch wipers into engagement with the iirst Contact on the third level and at the end of its stroke opens the interrupter springs 32, thereby causing relay G to release.
  • test wiper 34 will encounter earth and relay G will be operated in a circuit extending over off-normal springs 26, interrupter springs 32, armature 28, contacts controlled by armature I2, to earth on the test wiper 34.
  • Relay G again completes its locking circuit at armature 24 and closes a circuit of the ro-tary magnet which advances the wipers on to the second contact. If this contact is also busy, the same sequence of operations occurs and the wipers are stepped on to the third contact. When an idle line is found, wiper 34 will no longer encounter earth and relay H will then energize in series with relay G, which latter however is not energized in this circuit owing to the high resistance of relay H.
  • Relay H extends the speaking leads to wipers 33 and 35 at armatures 21 and 3U and extends the incoming test conductor through to the test Wiper at armature 28. Relays A and B thereupon release but before relay B releases, earth is received back over the test wiper 34 due to the operation of relays corresponding to A and B in the succeeding switch. Relay H is now held in series with relay G by earth fed back over the test wiper and when this earth is removed upon release, relay H releases and completes a circuit for the release magnet Z which extends by way of armatures 29, I8 and 2
  • connection is to be extended over one of a small group of lines for example group 3, but that all the lines in this group are busy.
  • the operations which now take place are the same as those previously described except that the switch will fail to find an idle line and will continue to step until it reaches the fifth set of contacts.
  • 'I'hese contacts are connected to a busy tone set arranged in the manner sho-wn in Fig. 3.
  • This busy tone set is multipled to the vacant contacts following the various small groups as shown in Fig. 2.
  • the test contact of the fifth set of contacts in the third level will therefore be disconnected when the busy tone set is not in use and, as will be seen later,.will be connected to earth through a high resistance when the busy tone set is ⁇ already in use.
  • relay H will operatev and connect the speaking and test leads through to the busy tone set whereupon relay A2 .willfop ⁇ crate and complete a circuit for relayBZ Whichin turn will connect a high resistance earth to the test contact to hold relay H operated.
  • Busy tone is fed back over the calling line through the lower winding of relay AI and the callingsubscriber will thereupon hang up and allow the switch to restore to normal in the mannerpreviously described.
  • connection is to be extended over a large group of lines, that is, a group occupying'more than one level and that in the rst instance there is an idle line available in the level corresponding to thedigit dialled. It will be assumed that the digit dlalled is the digit 2.
  • the operations previously described take place up to the end o-f the secondimpulse, whereupon a circuit is completed over the vertical wiper VW as follows: earth on the test wiper 34 or on armature 24, high resistance HR, vertical wiper VW, second contact in the vertical bank VB, upper low resistance and lower high resistance windings of relay 2 in series, armature to resistance battery.
  • Relay 2 operates and at armature '
  • Relay 2 vat armature 80 connects ⁇ earth to those contactsin the bank engaged by wiper 92 of the switch SW2 which correspond to those contacts of the second group whichxare not located in the second level.
  • Relay X at armature 15 extends earth over armatures 54 and 5I to the magnet RMI of the rotary switch SWI and extends earth over armatures 54 and 81 for the rotary magnet RM2 of the switch SW2.
  • the magnet RMI interrupts its own circuit at springs 50 and continues to operate intermittently and.
  • relay Y as follows: earth on the test wiper 34 or on armature 24, bank and wiper 4
  • Relay Y on operating disconnects itself from wipers 4
  • Magnet RM2 similarly interrupts its own circuit at springs 9
  • Relay W on operating completes a locking circuit for itself over armatures 89, 82 and 3l. It ,will thus be seen that the switches SWI and SW2 at wipers 43, 41 and 48 and wipers 93, 9B and 91 respectively serve to prepare a connection from the switch originating the call to an idle line of the second group which is not located on the second level. No further operations however take place in the common overiiow link as it has been assumed that there is an idle line in the second level. When this line is found relay H energizes in the manner previously described.
  • relay G is not re-operated, so that the earth on wiper VW is removed whereupon relay E releases and opens the circuits of relays X and W at armature 8l.
  • Relay X in turn at armature 'l5 opens the circuit of relay Y and the overflow link is thereby restored to normal, the wipers remaining in the position to which they were set. The connection is completed by the switch GS in the manner previously described without the assistance of the common apparatus.
  • connection is to be extended over a large group of lines and there is no idle line available in the level corresponding to ⁇ the digit dialled but that an idle line is available to the overflow switch SW2.
  • digit 2 is dialled and in this case the same operations take place as previously described up to the hunting operation of the switch GS, and the overow link is caused to operate in the manner already described in response to the initiation of the hunting movement.
  • the switch GS continues its hunting operation but as all the lines in the second level are busy it advances to the 11th step position and operates the 11th step cam springs l5, l'l, and 3
  • a circuit is thereupon completed for relays K and V as follows: battery, winding of relay K, cam springs l5, bank and wiper 49, armature 53, winding of relay V, armature 9i) to earth, as it may be fairly assumed that the faster operating switches SWI and SW2 will have completed their hunting operations before the switch GS has reached its 11th step position.
  • Relay K upon operating completes a locking circuit for itself at armature i4; disconnects test wiper 34 at the contacts of armature l2; and at armatures Il, I3 and i6 transfers the incoming speaking and test leads from the switch GS to the common apparatus, while relay V at armatures 59, 51 and 69 eX- tends these leads through to the idle line selected by the switch SW2.
  • the resetting of the switch GS is effected by sending impulses from the overflow link so that in ⁇ the example chosen it will be necessary to send three impulses to the vertical magnet V and nine impulses to the rotary magnet R.
  • Appropriate connections extend from the bank contacts engaged by wipers 94 and 95 of the switch SW2 to a terminal block TB the contacts of which are wired to impulse sending cams arranged to transmit series of earth impulses corresponding in number to the number shown adjacent to the various terminals of the block TB. Three of the cams are shown in the drawings to illustrate their mode of operation, the remaining cams are arranged in an analogous manner.
  • the terminal on the terminal block corresponding to the tens digit of the selected line is connected to the corresponding contact on the bank engaged by wiper 94 and the terminal on the terminal block corresponding to the units digit is connected to the corresponding contact on the bank engaged by wiper 95.
  • a start cam which connects battery to the lead S for a. short interval before the transmission of any of the impulses in the series
  • a stop cam which connects battery to the lead Z shortly after battery is connected to the lead S but before the rst numerical impulse is sent and disconnects this battery when the last numerical impulse has been sent.
  • relay DA When battery is next connected to the lead S, following the operation of relay V, a circuit is completed for relay DA as follows: resistance battery, lead S, armature 68, middle winding of relay DA, armatures 59 and 59, test wiper 93 to earth fed back from the succeeding switch.
  • Relay DA thereupon operates and locks over its lower winding by way of armatures 65, 59 and 58.
  • battery is connected to the lead Z and a circuit is thereupon completed over armature i3, the upper winding of relay DB, a1'- mature 64 and the upper winding of relay DA to earth.
  • Relay DB operates and relay DA is held in this circuit.
  • Relay DB locks operated over its lower winding and armatures 6l and 59 to earth on the test conductor.
  • a series of three impulses is sent over wiper 94, armatures 'l0 and 9 l, wiper 44 and bank contact to the vertical magnet V which thereupon raises the switch wipers three steps.
  • relay H energizes in series with relay G due to the closing of the off-normal springs 25, but no other operations take place at this time.
  • relay DA releases, as the circuit of its lower winding is now open at armature 69, and completes a circuit for relay RC over armatures 63 and 65.
  • Relay RC operates, at armature 'l2 completes a locking circuit for itself to the test conductor and at armature 73 prepares a fresh circuit from lead Z so that when battery is neXt connected to lead Z a circuit is completed for the middle winding of relay DA over armatures 13 and 63 to earth on the test conductor.
  • Relay U also energizes in parallel with the middle winding of relay DA and closes a locking circuit for itself in series with relay T. Relay T, however, being shunted by the Z lead, remains quiescent.
  • Relay RC also opens the circuit from Wiper 94 at armature 'I9 and closes a circuit from wiper 95 at armature H so that when the impulse sending cams next come into operation a series of nine impulses is transmitted over wiper 95, armatures 'H and 92, wiper f' f springs Il. Relay His prevented from operating I to operate.
  • relay T When battery is next removed from the lead Z, relay T operates in series With relay U over armature 'I4 to earth on the test conductor. Relay T Yat armature 98 opens the locking circuit of re- Ilays W and Y which thereupon release and at armatures 90 and 53 open the circuit of relays V and K which thereupon release. Relay K transfers the incoming leads back again from the common apparatus to the switch GS, and as relay H is already operated these leads are extended ythrough to the succeeding switch connected t0 ⁇ contact set 39.
  • Relay K is adjusted so that armature !3 opens slightly after the springs controlled by armature l2 have closed so as to ensure continuity of holding potential on the test conductor.
  • Relay V releases shortly after relay K and at armature 55 opens the locking circuit or relay X which in turn at armature 16 opens the locking circuit of relay Y whereupon vall the common apparatus is restored to normal.
  • the relay which is operated when all the lines in the group become busy could be arranged to connect earth back over the bank VB and wiper VW and by a suitable modification of the circuit connections cause the switch to hunt to its 11th step position, whereupon busy tone would be fed back to the calling subscriber through the lower winding of relay A.
  • the group contact arrangement just described might be utilized to indicate that the ten lines of a large group which are on a single level are all busy and so pre-operate relays such as 2 and mark the level contact in the vertical bank to enable the overiiow connection to be set up more quickly.
  • the resetting may be eiected as Along as contacts are available on the switch GS and the switches SWI and SW2 used as a permanent by-path connection throughout the conversation link as the registersender may readilybe arranged to delay the transmission of the digit until the group selector has been reset. In this case it is not necessary for the auxiliary switch SW2 to have access to the line contacts of the overiiow ,y
  • the overflow link may bev modifled to control both its associated group selector and the switch selected in the next switching stage.
  • a iinfal selector of this type which is often referred to as a P. B. X. final selector, vis arranged so that when set on to the first line of a group, and this line is busy, it performs a hunting operation until it finds an idleline in the group or until it comes to the last contact inthe group.
  • the iinal selector is also generally arranged to have access to ordinary or individual lines which it tests in the usualmanner vand thereupon connects ringing current toI the called line if idle or connects busy current tov the calling line if the called line is busy.
  • a very important requirement ⁇ in connection with final selectors of this type is that of allowing for expansion of the 4groups of lines orV the Yconversion of an individual line to agroup of lines and it is very desirable thatl all the contacts connected to lines leading to a particular branch exchange should be made accessible to the nal selector in response to the diallingof asingle number which will remain unchanged yin spite of any increase in the number of lines leading to particular branch exchanges. To meet this requirement, it is generally necessary that. all the lines in the groupshall appear as consecutive lines in the bank of the selector.
  • the circuit shown in Fig. 5 is a well-known ⁇ circuit which has been modied by the addition of a resistance HRI, a wiper
  • relay Al operates over the speaking leads and at armature ll completes a circuit for relay Bl which also operates and at armature
  • relay Al releases intermittently and at armature repeats the impulses over armature H0, off-normal springs
  • a parallel circuit extends over armature
  • On the first vertical step the o-normal springs are operated and the subsequent impulses to the vertical magnet pass from armature H0 over springs
  • relay C releases.
  • relay AI again releases intermittently and at armature l0! repeats the impulses by way of armature H0, springs
  • the rotary magnet rotates the wipers a corresponding number of steps, for example 6, so that they now stand in engagement with the terminals of the line 26.
  • a parallel circuit also extends to the lower winding of relay E which operates and, at armature
  • 28 places a shunt across armatures
  • the calling subscriber On receiving the busy tone the calling subscriber will hang up his receiver whereupon relays AI, Bl and Gl will release and a lcircuit will be completed for the release magnet Zl over armatures
  • the release magnet causes the switch wipers to restore to normal and at armature
  • battery encountered by test wiper
  • Relay Hl operates and at armature
  • relay Hl extends ringing current to the wanted line from the lower vwinding of relay F and the ringing lead RT, a small portion of the ringing current being transmitted to the calling subscriber over armature
  • relay F operates over its lower winding in series with the called loop, holds over its upper winding and completes the talking connection.
  • Relay D operates over both its windings in series with the called loop and at armatures
  • the switch wipers are positioned on the second set of contacts in the fourth level in a manner similar to that already described. If the first line in the group is idle the connection is extended over this line in the manner already described. If, however, this line is busy, relay Gl operates, and as the wipers are engaging the lirst contacts in a P. B. X. group, wiper
  • Relay Cl thereupon operates and at armature
  • Relay HS completes a locking circuit for itself over its upper winding at armature
  • a circuit is also completed for the rotary magnet as follows: battery, winding of rotary magnet Rl, armatures
  • No. 15 is an individual line which has one further line left' spare in sequence for possible extension;
  • No. 42 is a P. BJX. group of lineswith possibilities of exftension to lines in sequence up to 7.
  • the subscribers having groups of lines with the later choicesout of sequence are Nos. 19, 88 and 01.
  • Subscriber No. 19 is a P. B. X.' subscriber with two lines on contacts I9 and I0 respectively, V.and a third line on contact 28; subscriber No. 88 has a single line connected to contact 88,' and a second line connected to contact 64; while subscriber No.
  • completes a circuitf for relay XI which causes the switches SW2I and SWII to operate in a similar manner to that described in connection with Fig. 4, the
  • relays WI and YI operate and prepare a circuit for relays VI and KI in series.
  • Relay KI however only energizes if there is an absence of earth on the junction point between its winding and resistance R2 and this can only occur when the wiper
  • relay GI earth Due to the release of relay GI earth isv disconnected from wiper
  • armature 250 opens the circuit of relays KI and V
  • the circuit then divides, part proceeding via contact 2 I2, locking contact of relay XI to relay XI and battery and also a branch extends through a back Contact of relay TI, locking contact of relay WI, relay WI, resistance to battery, while the other part of the circuit from wiper 232 proceeds via armature 2I3, wiper 254 to the cut-off relay of the wanted subscriber.
  • Relay HI operates in this circuit and completes a locking circuit for itself at contact I3I through its upper winding.
  • 29 connects earth from Wiper
  • relays DAI, DBI, RCI, UI and TI operate in the same manner as the corresponding relays in the common apparatus associated with the group selector to control the transmission of two series of impulses over wipers 203 and 204 and conductors
  • Relay WI at armature 250 opens the circuit oi relays KI and VI and these relays thereupon release.
  • the switches SWZI and SWII will be set in operation as before but the switch SW2I will be unable to find an idle line in the required group so that no circuit will be completed for the relay KI.
  • the switch SWZI will then continue to hunt until a line becomes available or until the calling subscriber restores his receiver. If desired, it could be arranged that the switch SW2I is stopped in a special position when it has found all the lines in the required group busy and the switch FS could then be arranged to restore to normal to transmit a busy signal to the calling subscriber whilst at the same time releasing the common apparatus.
  • FIG. 8 this shows a subscribers station S which is automatically connected, when a call is initiated, to an up-andaround rst group selector such as SI.
  • a rotary auxiliary switch RBS is associated in common with a group of selectors such as SI either by means of multiple connections as shown in Fig. 8 or by means of a hunting switch.
  • the auxiliary switch RBS is automatically connected to the selected first group selector SI and selects an idle line leading to the tandem exchange T and terminating in a group selector S2.
  • the rst series of impulses transmitted by the calling subscriber is received by theselectors SI and S2 and causes their wipers to be stepped vertically to the corresponding level; they then hunt over this level for an idle junction to exchange B, assuming that B is the wanted exchange. If the selector SI finds an idle direct junction the lconnection is completed thereover and the switches RBS and S2 are restored to common use. If, however, no direct junction is available, then the connection is completed over the junction tothe tandem eX- change T selected by the auxiliary switch RBS and the junction to exchange B selected by the gro-up selector S2 at the tandem exchange T.
  • the indirect junction selected by the switch RBS is also connected to a suitable contact set in the bank of selector SI so that when it is known that no direct junctions to exchange B are available the selector SI is released and is set on to the junction selected by the auxiliary switch RBS in a manner similar to that described in connection with Figs. 1-4. The switch RBS is then released and restored to common use.
  • the indirect junctions may be connected to a different level of the selector SI from that to which the direct junctions are connected, the indirect junctions for handling overow calls to a plurality of different exchanges may all be connected to the same level or levels of the selector SI. In any case, all the indirect junctions will be accessible to the auxiliary switch RBS and will therefore form a single group with a resultant increase in efciency.
  • the group selector SI may be of the type which is set on to the required group of lines in response to two series of impulses.
  • SI is an up-andaround iirst group selector provided with two sets of banks of 100 lines each and with a separate set of wipers for each set of banks, a switching device X being provided for switching over from one set of wipers to the other.
  • RBS is an auxiliary switch which is preferably of the up-and-around type and is associated in common with a group of selectors such as SI either over multiple connections as shown, or over a hunting switch.
  • the group selector SI and the auxiliary switch RBS are automatically taken into use.
  • the wipers of the selector SI are raised to the corresponding level and then select an idle second group selector such as S2.
  • the wipers of the selector S2 are raised to the corresponding level and then select an idle final selector such as FS.
  • the circuit is arranged so that the switch RBS responds simultaneously to the second digit so that its wipers are raised to the third level.
  • the wipers are then rotated to select a contact corresponding to the iirst digit, e. g., under the control of a circuit extending over a vertical wiper of the selector SI.
  • the rst and second digits are 2 and 3 respectively so that the switch RBS will select a contact (e. g. the second) in the third level.
  • lines extend direct to nal selectors; these lines are also connected to the bank of the selector RBS.
  • a direct line may extend from each contact of the lower bank to a final selector having access to a different group of one hundred lines.
  • the capacity of the exchange will generally be substantially less so that for certain combinations of the iirst two digits two or more direct lines may be provided leading to diierent final selectors having access to the same group of one hundred lines particularly in cases where the corresponding nal selectors carry heavy trafc, e. g., to P. B. X. groups.
  • the switch S2 hunts for an idle nal Selector FS in the usual manner. Simultaneously, the auxiliary switch RBS operates to select a direct line leading to a final selector having access to the same hundreds group of lines, which selector as shown is also FS but need not necessarily be so. If such a direct line is found to be idle, then a temporary connection is completed over the switch RBS to the nal selector FS and the selectors SI and S2 are released.
  • the operation of the final selector FS may now be controlled over the temporary connection and while this is taking place the selector SI is automatically reset'under the control of the switch RBS to extend a connection over its lower bank to the final selector FS via the direct line, and when this connection has been completed the temporary connection is opened and the selector RBS is restored to common use.
  • the selectors such as Sl may be divided into groups each having access to different final selectors so that calls will only need to be set up via selectors such as S2 when more than one call from a particular group of selectors such as Si is being set up simultaneously to a particular hundreds group of subscribers.
  • connections may be set up over only two numerical selectors, namely, SI and FS, instead of three as would otherwise be required, namely, SI, S2 and FS.
  • Fig. 4 shows an arrangement whereby speaking connections may be set up over uniselector switches which may have capacity of considerably less than lines.
  • Sl is a uniselector first group selector which may have a capacity of substantially less than 100 lines, e. g., only 25 lines; and RBS is an auxiliary switch associated in common with a group of selectors such as SI either over a multiple connection as shown or over a hunting switch and is preferably of the up-and-around type.
  • the uniselector Sl and the up-and-around reserve by-path selector RBS are automatically taken into use.
  • the selector Sl In response to the dialling of the first digit, the selector Sl is set to a corresponding group of lines; this may be effected by arranging that the switch RBS is set vertically in response to this digit and extends a marking circuit over its vertical wiper to the bank of the selector Sl'. The selector Sl then hunts for an idle line in the marked group (which may contain only two lines) leading to a selector such as S2, and if such a line is available the connection is completed thereover and the switch RBS is restored to common use.
  • the switch RBS hunts for an idle uniselector, such as OS2, in a group of overow uniselectors having their banks multipled with those of S2, whilst at the same time the uniselector Sl hunts for an overflow selector such as OS in a common group.
  • the selectors OS are preferably of larger capacity than the selectors Sl and as shown in Fig. 4 they may be of the upeandaround type.
  • the selector OS is then set on to the line leading to selector OS2 under the control of the auxiliary switch RBS.
  • the connec tion is then completed over the selectors Sl, OS and OS2, whilst the switch RBS is restored to common use.
  • a similar overow arrangement may be provided at the second switching stage as is illustrated in the drawings by switches RBS! and OSI.
  • the lines from the first selector SI to the second selectors S2 will carry quite a large proportion of the traii'ic, the remainder of the traffic being routed over the overow selectors OS and it will be appreciated from the wellknown grading principle that this results in an economy in the total number of switches required. If desiired, the auxiliary switch RBS and the selector OS may also be uniselector switches.
  • a selector switch having its contact bank divided into separately designated contact groups, means responsive to control corresponding to the designation of a contact group for bringing said selector into asn sociation with the designated group of contacts, there being lines connected to the contacts of said selector and grouped generally in accordance with the grouping of the contacts, means for causing the selector to search over the contacts 'of a selected group for an idle line, means ef fective in the event that an idle line is found for arresting the searching operation and for causing the selector to make connection with the idle line and effective in the event that all of the lines connected to the contacts of the group are busy for arresting the operation of the selector when the end 0f the group is reached, certain of said groups of lines having more lines therein than there are contacts in a group, the additional overflow lines being connected to spare contacts in other contact groups, an overflow link associated with said selector and having access to the overflow lines, means effective when the selector is brought into association with a contact group serving a group of lines
  • a selector switch having its contact bank divided into separately designated contact groups, means responsive to control corresponding to the designation of a contact group for bringing said selector into association with the designated group of contacts, there being lines connected to the contacts of said selector and grouped generally in accordance with the grouping of the contacts, means for causing the selector to search over the contacts of a selector group for an idle line, means effective in the event that an idle line is found for arresting the searching operation and for causing the selector to make connection with the idle line and effective in the event that all of the lines connected to the contacts in the group are busy for arresting the operation of the selector when the end of the group is reached, certain of said groups of lines having more lines therein than there are contacts in a group, the additional overflow lines being connected to spare contacts in other contact groups, an overiiow link associated with said selector and having access to the overflow lines, means effective when the selector is brought into association with a contact group serving a group of lines containing overflow lines for operating the overflow
  • a group selector having access to groups of lines which may be varied in size independently of the construction and manner of operation of the group selector, whereby certain overflow lines are connected to contacts that cannot be reached in the normal operation of the selector, an auxiliary switch having access to the said overflow lines, means effective when the group selector is directed to a group containing overflow lines for causing the auxiliary switch to select an idle overflow'line of the group, and means effective in the even-t that all the lines of the group which can be selected by the normal operation of the group selector are busy for temporarily completing the connection to the selected idle overflow line by way of the auxiliary switch; for reoperating the group selector under the control of the auxiliary switch according tothe position assumed thereby to make connection with the same idle line; and for thereupon transferring the connection with the idle overflow line through the group selector.
  • a group selector having access to lines divided into groups, means for bringing said group selector into association with a group of lines and for causing it to search over the group in search of an idle line, overflow lines forming a continuation of one of the said groups, an auxiliary switch associated with said selector and having access to said overflow lines, means effective responsive to the operation of said group selector into association with the group containing the said overflow lines for causing said auxiliary switch to search for and connect with an idle overow line, and means dependent upon said group selector finding all lines busy in the selected group for transferring the connection to the idle overow line selected by the auxiliary selector.
  • a group selector having access to lines divided into groups, means for bringing said group selector into association with a group of lines and for causing it to Search over the group in search of an idle line, overflow lines forming a continuation of one of the said groups, an auxiliary switch associated with said selector and having access to said overflow lines, means effective responsive to the operation of said group selector into association with the group containing the said overflow lines for causing said auxiliary switch to search for and connect with an idle overflow line, means dependent upon said group selector finding all lines busy in the selected group for transferring the connection to the idle overflow line selected by the auxiliary selector, said group selector having access to said overow lines by way of spare contacts located at random in its bank, and means ⁇ eiective upon the finding of all of the lines in the main group busy and controlled according to the position taken up by said auxiliary switch for restoring said group selector and for reoperating it directively to make connection with the overflow line which has been connected with by the auxiliary selector.
  • a group selector having access to lines divided into groups, means for bringing said group selector into association with a group of lines and for causing it to search over the group in search of an idle line, overflow lines forming a continuation of one of the said groups, an auxiliary switch associated with said selector and having access to said overflow lines, means effective responsive to the operation of said group selector into association with the group containing the said overflow lines for causing said auxiliary switch to search for and connect with an idle overflow line, means dependent upon said group selector finding all lines busy in the selected group for transferring the connection to the idle overflow line selected by the auxiliary selector, said group selector having access to said overilow lines by Way of spare contacts located at random in its bank, means effective upon the nding of all of the lines in the main group busy and controlled according to the position taken up by said auxiliary switch for restoring said group selector and for reoperating it directively to'make connection with the overow line which has been connected with by the auxiliary selector, and means thereupon
  • a group selector having access to lines divided into groups corresponding to the physical grouping of the contacts in the bank of the selector, one of such groups of lines including overflow lines connected to contacts located in another physical group of the contact bank, an auxiliary switch associated with the .group selector, means eiective When the group selector is operated into association with the physical terminals of the main group having the said overflow lines located in another physical contact group for causing said auxiliary switch to assume a position corresponding to an idle one of the overflow lines, and means effective in the event that the group selector is unable to nd an idle line in the physical group with which it has been brought into association for releasing the selector after it has searched over the group and for reoperating it in accordance with the idleline position assumed by the said auxiliary switch to bring it into connection with the contact from which the idle overow line is accessible.
  • a selector having access to groups of lines, some of the lines of certain groups being accessible from positions on the switch apart from the positions of the other lines of the same group
  • an auxiliary switch having access to the lines which are accessible from the separated positions of the switch, means effective when the switch is operated into association with a group of lines containing lines separated as to position for causing the auxiliary switch to hunt for the called group and for an idle line in the group, and means effective in the event that all of the non-separated lines in the group accessible to the switch are busy and controlled from the auxiliary switch for causing the selector to establish connection with the line selected by the auxiliary switch.
  • a switching unit including a main selector and an auxiliary selector, groups of lines accessible to said switching unit and appearing in different arrangements in the banks of said selectors, means for operating the main selector to select a group of lines and to select and seize an idle line in the group, means controlled from the main selector for causing the auxiliary selector to select a different idle line in the same group, and means controlled from the main selector depending upon its being unable to iind an idle line for causing the auxiliary selector to seize the idle line it selects.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
  • Exchange Systems With Centralized Control (AREA)
US5735A 1934-02-21 1935-02-09 Automatic or semiautomatic telephone system Expired - Lifetime US2106897A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5764/34A GB433475A (en) 1934-02-21 1934-02-21 Improvements in or relating to automatic or semi-automatic telephone systems

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US2106897A true US2106897A (en) 1938-02-01

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US5735A Expired - Lifetime US2106897A (en) 1934-02-21 1935-02-09 Automatic or semiautomatic telephone system

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US (1) US2106897A (de)
DE (1) DE687640C (de)
FR (1) FR786377A (de)
GB (1) GB433475A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543003A (en) * 1943-04-08 1951-02-27 Int Standard Electric Corp Selection control for telephone systems
US2787662A (en) * 1950-10-25 1957-04-02 Siemens Ag Automatic telephone system having switching means for routing calls in different traffic directions
US2981803A (en) * 1955-12-28 1961-04-25 Bell Telephone Labor Inc Program switching system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543003A (en) * 1943-04-08 1951-02-27 Int Standard Electric Corp Selection control for telephone systems
US2787662A (en) * 1950-10-25 1957-04-02 Siemens Ag Automatic telephone system having switching means for routing calls in different traffic directions
US2981803A (en) * 1955-12-28 1961-04-25 Bell Telephone Labor Inc Program switching system

Also Published As

Publication number Publication date
FR786377A (fr) 1935-09-02
DE687640C (de) 1940-02-02
GB433475A (en) 1935-08-15

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