US2454770A - Identification circuit arrangement for automatic or semiautomatic telephone systems - Google Patents

Description

L. A. B. CABES Nov. 3o, l1948.

IDENTIFICATION CIRCUIT ARRANGEMENT FOR AUTOMATIC OR SEMIAUTOMATIC TELEPHONE SYSTEMS.

Filed Jan. 22, 1943 'Lf l INV ENT OR.

L CASES ATTO vEY switches or :similar apparatus.

Patented Nov. 30, 1948 Lucien A. `B. ,Cabes, Antwerp, 'Beigiiim as`signor v'to I International Standard TEllectric .brporationgN ew York,`N."Y

., a. cornorationfhlaware In thetNethe'rl "settima, Public Lawjsgp; musketiers Paneex'pires April 2539er -lainis. 1

This invention relates `:to f new `and f useful improvernents in `control "circuits 'for automatic hunting or selectorswitchesand'the'likej such as are useful intelephone'orfother communication systems ine which Valternating `currentfn'iarker xpotential is applied to groups of marking wires.

Accordingizto lone lof the featuresfoflthelinvention the marking wires in such a seiectoriswitch are individually connectedtdmarking contacts of one: or more final selectorsor similar '.apparatus, and further groups s of 'fmarking Iwires- 'are .i each connected through resistances, in'ductionv'coils, reotiiierspor a fcombination of'two V'or hmorefof these elements, orcombinations ot such elements with condensers, to a common point. group of `.marking .wireszis connected at ithis common pointwithfafgroup marking twire, and

`the group marking wires are in turn-connected with marking contacts of one :or :more finder The same. alternating current marker potential whichqisf'connested to an individual marker wire, `serves *fas "a test potentialffor ndingthefindividual marker wire in the apparatus ifor :individual `asie'ction,

was well as 4forzinding the groupfrnarkingWire` during the hunting roperation inf 4the"fseletor i switch.

with two-motion nal selector switches, which maybe used for-many-otherpurposesfe. g.:t1'unk hunting, line identiiication, etc. According :to the invention the subscribers linesrmayiforiidentication purposes, be marked by alternatingcun rent marker ;potentials, 'fwhile `other groups of marker Wires areeach `connectedivia'rresistances, inductance coils, rectiers, or a` combination 1 of `two or more of these elements orwith conde-risers,

(all of which `I intend to cover by :the `*word impedance) to a conimonipoint 'at which :this l group of `marking wires is `connected' tlm-af` group marking'wire. These group marking'wresfare connected to fmarking contacts f of 'group identification switches of identification `circutssanii the final selector isset,:for group selection'zfroml the identification -circuit1byarseries of (impulses, the number of vwhich is automatically determined `by the setting ofthe :group identicationvswitch.

The setting of the group identification switch-,on the group marking wire yas well as the" hunting 'for the individual markingiwire'bytheiinalcselector takes .place under the :control of detector Ittis wellknownethat Acondensersusei "tofpre- (clairsisi f vent l the passage offidirectfcurrent'f over armam- `f`ing' wire,ffe. g:ithe-"owire of atseleetorfwoultihave ^1an influence 'fon other l-rnarking lwires land :cause l the undesirable response 1 f I@relays or r other Tefr ceivingapparatusfconneetedfto Jthese-v'ires. A'` Such faicondenserlallows of course,falternatingl current to pass to a detector.

*The -fcharging @and fiiseh'arging fof A@such` "con- 'densei whenufa f change; 'of uvp'otei'itiei'l ttaliesrplace l,10 iini:thefcewiresgiwouldscause the detectortowreact. 21 /ior.eovery :an indiviiualreondenser is Jrequired iforf each'iline and, 'even at rather Lhighfrequencies, g. F1500 .Hz/sec;,f a1-0i3 cnilFfcondenser must tbe provided 'lLiie-.fcommonifpointimustpe connected l215 'i to i a l predetermined :direct :.i'currenti` 4potential Lto apply bias '.to'vithe contacts. oflthe nder switch, @wihiehlhuntsffonall'common pointsito itientitythe :group'imarking wires to whichithefalternating current lt'o fbe.- detectedis'fconnected .ifAll l:20 fmakes ithe arrangement expensive;

iinsor'der toneuuceithefcostsga high frequency znmstibefznsed.. ,l-Iowfever,f` on-:acount-:nfthe danger :of ,mutual iiniiuence, the rfpotential must fbe low and the detector;veryi'sen'stive.` ifhisrigreatfsensin i125 tivityzmay .'.zcause @an undesired :response sof.:the

fdetector :fapparatus tonfaccountlwf. :ithezfaboveimentionedtbias.

fiygusingznesistances oislsuicentiyrhigh value, (e. i500 ohm), according-'Lto:thelinventonithe so rzchargingzzaifd #discharging "of the fconden'sers .will the avoide'dtand l. equal `+tbiasuwill be `eiautomatically iappliedfto the contaetsfbecauserithe?resistancesare :permanently zconnected nto `:the .1: source Y of 1 direct ourrent..fpotentia1. Furthermore; the frequency 35 xmayrbetreducediand'ithefiaiternating eurrentcpo- :tential f'increasemithus s makingcfpossi'ble 'fthe :1 em- `:.ployrxient i of 4 a less `'sensitive z detecten". apparatus. .Disturbing:inuenceaby therbias .'is then f avoided. The'fspacesiiequirezd foritheffapparatusiis smaller ,40 yrwhen iresistances :areinsedaand uw' the costi is oonrpsiderablyifl'owerfthan .Withvpxfior systems.

The c-wires in accordance with the rpresent i embodiment: aresteonneotedzpveratwice. iuc ohm, Iire;1'3Onitino-hnr: soi'thatzoniygafveryrwealgcurrent 45 .fowsj ibut fthis :gis insuicient *to vproduce :any i in- ;iiiuerrcee from one;iineatoatheother.

'Thal invention zwill 'be describeidfasfembodiedn "ai telephone :systemz'which: is xdiagrafmmatcailydi Ylustrai'fed intt'he idrawi-ng. U50 i Onlysthosegpartsofthe'systemfare shown;:which farexusedvin ,the lneidentication arrangement :oal'telephonefexchangeemploying power driven rotary switches. The liinal A'seixtors *have tten levels of twenty I vsubscriioers'.` terminals, andare ys55 ummisrlleki f'by i revertive impulses from a* register 3 controller set by the calling line in accordance with the numerical designation of the called line. For connection for which the identication of the calling subscriber is required, is first built up over the customary first and second line nders or other non-numerical switches, and then extended to an exchange which acts as -a nodal f point for toll connections in a given area, (hereinafter called main exchange). From this point, the connection is established over one or more selecting stages which are not shown. The identification may be initiated from the main eX- change at any appropriate moment. The manner in which the identification starts at the main exchange will not be described because it forms no part of the invention, which has to do with the switching operations for determining the number of the calling subscriber.

The identication is performed by two control circuits; one attached to the second line finder and the other to the subscribers line circuit. The rst control circuit is the identification-calling circuit, of which parts are illustrated in the right lower part of the drawing. The other circuit is the identicatiomsending circuit, of which parts are shown schematically in the left lower part of the drawing.

When a call is initiated on a subscribers line, a free identification-calling circuit is connected to the circuit of the second line finder which, in a manner not disclosed here, is marked by the calling line. Relay Cr responds and a calling tone of 450 cycles is connected to a path over the c-wire of the line circuit of the .calling subscriber.

The subscribers' lines are so arranged in the ter-` minal banks of the first line fingders, and the latter on the banks of the second line finders, that an equal distribution of the trafc is obtained.

A second line finder circuit cannot identify the numerical group to which the calling line belongs. The identification-sending circuit will, however, find the calling tone which was placed on the line to be identified. In exchanges, in which the number of lines is larger than the normal capacity of a finder switch, the identifica-i tion-sending circuit cannot have direct access to all lines by means of a single switch. -In such cases the tone is picked up in two steps by the identification-sending circuit,

The subscribers lines are divided into groups and, a common tone wire is provided for each group. This wire is connected to the bank of a rst switch. The number of terminals in this first switch is thus reduced to the number of common wires representing subscribers line groups, and the rst switch must first determine the group of subscribers lines to which the line to be identified belongs. The second purpose of this switch is to indicate the particular switch to which this group of subscribers is Connected, and then to find the individual line on whose c-wire the calling tone was placed.

The common points of the common tone wires, and which represent a certain number of individual c-wires, may be provided in different Ways. The c-wires must, however, be so connected to the common points as to avoid interference between the c-wires when direct current switching operations are performed over them. For eX- ample, resistances of 15,000 ohms are connected between the individual c-wires and the common point. The interference between the c-wires is then practically non-existent owing to the high value of these resistances and to the fact that the common point is connected through allow re- 4 sistance to a point of the same potential as that to which the c-wires are individually connected, viz. the winding of transformer TT, which is connected to the same battery potential as the apparatus, (Cor. SM), connected to the c-wire.

In the construction illustrated, 20 c-wires are commoned over individual resistances. The 20 subscribers lines thus multipled belong to one level of the nal selector. In an exchange of 10,000 lines there are, therefore, 500 such common points, which have to be hunted over by the tone wire finders of the first switching stage. Assuming that this finder ICF is a -point switch, the 500 common points are arranged in iive levels thereof.

The hunting for the calling tone may be cari ried out in many different ways. Five levels of 100 terminals each can be hunted over consecutively by a tone detector circuit, like the one indicated in the left lower part of the drawing. Another way is to provide in the identificationsending circuit five tone detector circuits, i. e. one for each tone wire nder brush cooperating with a level of the nder bank. While more expensive, this arrangement insures a quicker operation.

The current path for the calling tone is as follows:

Current source for a calling tone of 450 cycles, right front contact of relay Cr, retardation coil RC1, condenser C1, brush a and terminal of finder CCF, brush g and terminal of second line finder, brush c and terminal of rst line finder, resistance of 15,000 ohms, primary and secondary windings of transformer TT, terminal and brush a of finder ICF, winding of transformer IT1, earth.

The purpose of the transformer TT is to step up the voltage of the calling tone and to eliminate interference between the multipled c-wires.

When the indication is received from a calling circuit, the brushes of the ICF finders of each free sending circuit start to rotate. When the calling tone is encountered, the voltage of the control gap of a cold-cathode tube TV1 is increased beyond the breakdown Voltage, and the tube becomes ionized, This results in the operation of relay Itri, which opens the circuit of the power magnet, and the brushes of the switch ICFI stop on the terminal to which the calling tone is connected.

Each position of finder ICF represents ve levels each of twenty lines, all belonging to the same group of nal selectors. A second finder IFF, forming part of the identification-sendingcircuit now seizes a free nal selector which has direct access to the c-wire of the calling subscriber, The trip spindle of the final selector is set in the usual manner to the level, which includes the line of the calling subscriber. This setting is controlled by the brush of finder ICF on which the calling tone has been detected.

The brushes of the final selector start to rotate, while a tone detector circuit IT is connected to the c-brush. This tone detector circuit is composed of the same elements as the one (ITi) which tests the common points. Whilst the final selector is hunting for the tone, the revertive impulses sent from this selector will advance a step-by-step switch UM, by which a record is made of the number of terminals passed by the final selector brush before it reaches the calling tone. The well-known revertive impulse circuit comprises the relays Flr and Osr and the interrupter contact of the brush carriage.

Assoon as the calling tone is found, tube TV switches .at the first exchange for connecting calling lines with called lines at the first exchange, a set of contacts in the first group of non-numerical switches and terminals in` nal selector switches to which said lines are multipled, contacts in a second group of non-numerical switches connected with switches inthe first group, inter-office connections extending from the second group and the brushes of final selectors to the second exchange, groups of third, fourth and fifth non-numerical switches at the second exchange, the connections to the second group of switches `being multipled to the third group and those to the final selectors lbeing multipled to the fourth group of switches, a source of alterhating calling current of predetermined frequency connected in multiple to the third group of switches and overv an operated switch of the second and third groups to a terminal of the calling line connected to a switch of the first group, a connection from the terminals of a group of lines to a common point at the first exchange, a resistance in each connection, transformers at the second exchange having primary and secondary windings, a connection from each common point to the primary of a diiierent transformer, ,multiple connections from the secondaries of said transformers to switches of the fifth group,a detector at each switch of the fifth group responsive to said source of alternating current, means controlled by a detector for stopping its associated switch when the switch connects with a transformer connected -to said A. C. source, another detector also responsive to said source of alternating current associated with each switch of the fourth group, an operating magnet for said final selector controlled by the last-mentioned detector, a counting device associated with each switch of the fourth group, means for starting the brushes of said final selector to move over the terminals of its ibank, means for operating said -counting device once for each set of terminals traversed by' the final selector brushes towards the terminals of the calling line, means controlled by the last-mentioned detector for stopping said final selector brushes on the terminals of the calling line, a device associated with the switches of the fourth group for producing impulses representing the designations of the lines at the first exchange, a source of A. C. yof different frequency for said device, a. receiver responsive to the last-mentioned frequency associated with each switch of the third group, and a circuit for connecting said device with said receiver including in series a, switch of the fourth group, the final selector, and switches of the first, second and third groups.

5. In ay telephone system, a plurality of exchanges, a plurality of numerically designated lines at the first. exchange, means including groups of first and second line finder switches and final selector switches at the first vexchange for connecting calling lines with called lines, a set of multiple terminals in the rst line finder and final selector switches for each of said lines at the first exchange, the terminals in the'nal selectors lbeing divided into a plurality of levels, brushes for the first line finders and the final selectors cooperating with the terminals in said switches, terminals in the second line finders connected with the brushes of the first line finders, inter-oice connections extending from the brushes of the second line finders and final se'- lectorsto the second exchange, groups of third,

lli).

fourthfand fifth finder switches at the second ex-change, each having a bank Iof terminals and cooperating brushes, the terminals of each fifth finder being divided into a plurality of levels, with each of which a different brush of the fifth finder cooperates, and the connections to the brushes of the second line nders being multipled to the terminal banks of the third finders and those to the brushes of the final selectors being multipled tothe terminal banks of the fourth finders, a source of alternating calling current of predetermined frequency connected in multiple to the brushes of the third finders and over an operated second and third finder switch in series to a terminal of the calling line engaged by the brushes of a first line finder switch, a connection from the terminals of a group of lines in the same level of the final selectors to a common point at the first exchange, a high resistance in each connection, a source of D. C. potential, electroniagnets for each line at the first exchange connected from one pole of said D. C. potential to the last-mentioned connection, transformers at the second exchange, each having a primary winding connected to the same and a secondary winding connected to the opposite pole of said D. C. potential, a connection from each common point -to the primary of a different transformer, multiple connections from the secondary of each transformer to the terminals in the saine level of the fifth nder, a plurality of detectors, each responsive to said sources of alternating current, and each connected with a different brush of the fifth finder, means operative upon the initiating of a call at the first exchange to operate one of said fifth finders to connect said detectors with its terminals in succession, means controlled by a detector for stopping the fifth finder when its Ibrushes connects said detector with a transformer secondary whose primary is connected with said A. C. source, another detector also responsive to said source of alternating current connected with the brushes of the fourth finder, an operating magnet for said nal selector controlled by the last-mentioned detector, a counting device associated with the four-th finder, means associated with the fourth nder for starting the brushes of said final selector to move over the terminals -of its bank, means for operating said counting devi-ce once for each set of terminals traversed by the final selector brushes towards the terminals of the calling line, means controlled by the last-mentioned detector for stopping said final selector brushes on the terminals of the calling line, a device associated with the fourth finder for producing impulses representing the designations of the lines at the first exchange, a source of A. C. of different frequency for said device, a receiver responsive to the lastmentioned frequency -connected with the brushes of the third finder, and a circuit for connecting said device with said receiver including in series the Abrushes and terminals of the fourth finder, the final selector, and the rst, second and third finders.

6. In a telephone system, a plurality of numerically designated lines arranged in groups, means including non-numerical and numerical switches for connecting calling lines with called lines, a set of multiple terminals for each line in a nonnumerical and a numerical switch, a contact for each switch cooperating with its terminals, a source of A. C. having a predetermined charac- 9 teristic, means including said non-numerical switch for connecting said source with the calling lines, a first devi-ce responsive to said source, means for connecting said device to a group of lines including the calling line, a second device responsive to said Source, means for connecting the second device with the contact of said numeri-cal switch, means including the second device for controlling the operation of said contact to select the terminals of the calling line, means for producing impulses identifying the lines, a source of A. C. of diierent characteristics for the last-mentioned means and a receiver responsive thereto, and a circuit including said numerical and non-numerical switches for connecting the receiver with the last-mentioned impulse producing means.

LUCIEN A. B. CABES.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,846,516 `Haines Feb. 23, 1932 2,267,950 Rhodes Dec. 30, 1941 10 2,284,870 Holden June 2, 1942 FOREIGN PATENTS Number Country Date 58,889 Netherlands Feb. 15, 1947

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