US1733602A - Telephone system - Google Patents

Description

Oct. 29, 1929. H, B, JOHNSQN 1,733,602

TELEPHONE SYSTEM Filed May 12, 1925 by ,my

Patented Oct. 29, l1929 UNirsie STATES YORK n y ,v Application flied kMay 12,k

This invention relates to telephone systems and particularly to improvementsin the supervision of straightforward trunking connections established through tandem trunks.

In prior systems of this type where connections are established from a subscriber in a local exchange through an A operators cord circuit, a tandem trunk terminating at a tandem exchange through an Outgoing trunk to a called subscribers station, the A operator is notiied by the extinguishing of the superswers the call by removing his receiver from the hook. This indication is usually given by the reversal'offthe battery over the tip and ring conductors of the tandem trunk, which reversal is translated into an increase of the yresistance on `the sleeve conductor of the A operators cord, resulting in the extinguishing ofthe supervisory lamp.

An object of this invention is to provide a greatly improved arrangement in tandem trunk circuits, whereby this kind of supervision, which is ordinarily termed high-low supervision, is effective over the talking conductors ofthe A operators cord circuit 1nstead of over the sleeve conductors as heretofore. f

Another object ofthis invention is to provide that the application of the usual tandem trunk group busy tone is established by means of the above mentioned supervisorycircuit arrangement without the aid of any yadditional apparatus. -I`

To attain these and other objects of the invention, there is provided, in accordance with one feature thereof, a relay rarrangement, the originating Operations of which take place through the ring conductor of an A cord and a tandem trunk when connected together without interfering withthe usual lighting of thesupervisory lamp andso arranged that whenv the called subscriber an-y swers, this relay arrangement is responsive to the reversal of the current on the line to extinguish the supervisory lamp, through the Operation of the usual supervisory relay over the tip and ring conductors.

Another feature of the invention resides in this, that the above relay arrangement is may be reached.

HERBERT B. JOHNSON, OF BROOKLYN, NEW YORK, Ass'IGNOR TOHBELL TELEPHONE LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A coRPoR-ATIONOF NEWl V TELEPHONE sYsTRiilry 1925.- Sekrikal No.y 29,688. n i

also operative to apply a group busy tone On f i f the sleeve of the first tandem trunk if kall lines 1n a group of such trunks are busy.k

The following det-ail description of theine vention should'be read in connection with the 1 accompanyingdrawing,fin which the outgoying endkof a tandem trunk, arranged inaccordance with this invention, is shown in connection with a portion of an A operators cordat a local exchange,fwhile the incom` ing end of this tandem trunk is shown sche- `matically at atandem operators ,position kin a distant tandem exchange Where a portion of astandard trunk circuit leading to another y local exchange is shown in sufhcient detail to enable the proper description of the invenr tandem ytrunk T; and the tandem operator TO at the tandem exchange, in answer to the usual signaling from the Ayposition, inserts plugk 3 of this tandem trunk into a jack L of the trunk TS leading toanother local exito the drawing, iny estabi change through whichthe wanted subscriber Y The insertion kof plug yinto yjack 2 closes `a circuit for theA lighting of the supervisory' lamp 6 as follows: battery, lamp 6, sleeve .terminals of plug 1 and jack 2 to ground nother circuitisr` through a resistancek 7.y

also completed `from the talking battery of `the A cord through the lowervright hand windingof the repeating coil 8, they super-y visory relay 9, the" ring'terminals of plugl andjackfQ, lower left'hand windingof repeatingy coil 10` fofr the tandem trunk, low

resistance winding` 11 and `highresistance. winding 12 of relay'13 in series to ground.y This circuit causes the operation of relay 13, .but dueto the high resistance windingc12 of this' relay, the supervisory y,relay 9 is notoperated at this time, thus permitting the sueration of relay 13 closes a circuit through the battery and lower armatureand back contact of relay 15, lower winding .of relay 16,

pervisory lamp 6 to remain lighted. The Opy winding of the polarized relay Mas follows:

n ring conductor of trunk T, fright handlower winding of a repeating coil 10,-winding'of relay 1dr-, upper armature and front contact ot'relay 13, upper right hand winding of refinding ot relayT 16, upper armature back Contact ot relay to ground. VIteis polarized soas not to operate on t urreut passii'rqv through its winding in t' J direction., However, relay 16 operates icatic-ns to be given to the tandeinoperator at. TG hat a through connection is desired.

Tnanswer to this indication, the tandem operator at .TO communicates with the A operator and. on receivingthe-proper direction 4as to the extension of the connection inserts Vthe tip and ring leads through to the trunk 'TS follows: from the upper armature and 'iront'contact of relay 15 through the tip terminals of plug 3 and jack fl, upper left hand winding ot the repeating coil 18, left hand make-before-break contacts ofvrelay 19, left Y hand winding ot relay .toV ground and from *trunk v, frein the ,talkingibattery'fat V`the cord A' Y liroufh thelower'right hand winding of re-VV coily 3, thesuperviso'ry relay), the innalsoit plug 1 and jack V2, lowerY d Y'winding of repeating vcoil 10, low

voit' the supervisory relay 21. `,op r ting closes an energizing circuit for retlie lower armature Vand'iirontContact of relayi'l, over the ring terminals oit' plug 3 and jack fl, lower left hand winding of repeatfing coil 13, right hand make-beore-break contacts oi relay 19 and right hand winding of relay 2O to battery. Relay 20 is now operated and, as is well known in the art, nidications are given at the distant local oflice,

(not shown) that a connection with a subscriber at this office is wanted.

lt'is now assumed that thewanted. subscriber is yconnected with and rung vin the usual manner and that the subscriber answers the call by removing his receiver from the hook, l' This action on the part of the called subscriber will result in the operation Relay 21 in 19 whiclrnow reverses the battery supply iorpola ized relay 141- by the Voperation of its armature 'in a manner which is believed to be oigcurr'ent and thus Vshunts the high resistance winding 12 oi relay 13, aiidrbridges the Alowresisten'ce winding 11 of this relay acrossV the tip and -ring conduct-ors Aof the tandem ne, circuit vis thereby established Y resistance winding 11 ot relay 13, armature' and Vfront contact yof relay A14, upper leftV liaiidwinding of repeating coil 1Q, tip terminais ot jackQ and plug 1, upper right hand in the usual manner, not shown, to cause in- K' armature and front Contact closing the shuntV to battery tor lamp 6 which is thereby eX- tinguished to indicate to the A operator that the subscriber at thedistance local exchange has answered the call. A

lt will be seen that, in accordance with this invention, the supervision as described above is effective through the talking conductors of tandem trunk circuit and the cord circuit and not as is the usual practice through the sleeve conductors. Y

Another featurefof the invention, which also is a step toward the simplification of the control of circuits of this type, is the application of group busy tone on the first trunk in a group ofv trunks. This is accomplished by'means of an armature and front Contact on relay v13 of the various tandem trunks in a group ot trunks. 'For example, if all the relays 13 ot'th'ese trunks are operated, a chain circuitl will be completed'as shown from the tone sourceV 25 `connected to the lower armature and front contact of the relay 13 of the last* tandem trunk in the group through the Y corresponding contacts of the relays 13 of the intermediate tandem trunks to the correspondingrarmature and front Contact of rel 13 on the first-trunk. Therefore, if all the while the application of trunk groupbusy4 tone is well known, the"arrangement of this feature in connection with the rsupervisory relay arrangement in the manner described is 'exceedingly simple Yas noi. additional apparatus isV required-except a singlei armature and contactY on the relay 13 of the various tandem trunks.'

What is claimed'is: y 1 In a telephone system, a cord circuit and a line circuit having respectively tip ring# and sleeve conductors and a corresponding plugand jack, a signal and a circuit therefor Yincluding'the sleeve conductors or" said cord circuit 'and line for operating said signal on the insertion of tlieplug'into the ack, a su-V "resistance winding, a' circuit including the" 12 ring conductors and said high and low resistance lwindings for maintaining the supervisory relay in non-operated condition and for operating said second mentioned relay,

pola'i'iz'ed'relay and a circuit therefor arranged to be closed on the operation of the second mentioned relay, means for supplying battery to said last mentioned circuit for the operation of said polarized relay and a circuit controlled by said polarized relay to cause the operation of the supervisory relay over the tip and ring conductors by shunting the high resistance winding of the second mentioned relay.

2. In a telephone system, a cord circuit having tip, ring and sleeve conductors and a supervisory relay in said ring conductor responsive to a low resistance connection established from the said tip conductor to the said ring conductor, a trunk line accessible to said cord circuit having a polarized relay and a second relay having high and low resistance windings, means for energizing said second relay upon the connection of said oord circuit to said trunk in a circuit including said supervisory relay and both said windings of said second relay in series, and means controlled by said polarized relay for connecting the said lowr resistance Winding of said second relay across the tip and ring conductors of said cord circuit.

3. In a telephone system, a cord circuit having tip, ring and sleeve conductors and a supervisory relay in said ring conductor responsive to a low resistance connection established from the said tip conductor to the said ring conductor, a group of trunk lines accessible to said cordcircuit, each said trunk line having individual thereto a polarized relay and a second relay having high and low resistance windings, means for energizing said second relay upon the connection of said cord circuitfto said trunk in a circuit including said supervisory relay and both said windings of said second relayv in series, means controlled by said polarized relay for` connectinrthe said low resistance winding of said second relay across the tip andfring conductors of said cord circuit, and means controlled byy all of said secondirelays of said group of trunks for establishing an all-trunks-busy condition.

4. In a telephone system, a cord circuit having tip, ring and sleeve conductors and a supervisory relayin said ring conductor' responsive to a low resistance connection established from the saidv tip conductor to the said ring conductor, a group of trunk lines accessible to said cord circuit, each said trunk line having individual thereto a polarized relay and a second relay having high and low resistance windings, means for energizing said second relay upon connection of said cord circuit to said trunk in a circuit including said supervisory relay and both said windings of said second relay in series, means controlled by said polarized relay for connecting the said low resistance winding of said second relay across the tip and ring conductors of said cord circuit,k a

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