US2346114A - Right-of-way telephone system - Google Patents

Description

c. s. RHOADS RIGHT-oF-WAY TELEPHONE SYSTEM Filed Aprill 29, 194s April 4, 1944.

III-II" mvENToR 4 jhoad TToRNEY Patented Apr. 4, 1944 UNITED `sTATlSzs lafrrrlyr OFFICE RGHT-OF-WAY TELEPHONE SYSTEM Charles Stanley Rhoads, Albany, N. Y., assgnor to American Telephone and Telegraph Company, a corporation of 'New York Application April 29, 1943, Serial No. 484,956

11 Claims.

This inventiony relates to telephone systems. More particularly this linvention relates to switching apparatus for telephone systems. Still more particularly, this invention relates to arrangements for enabling a party to seize a busy line and permit him to signal over the line. I

When a telephone omce such as community dial office and a telephone oiiice such as an'operator or master oce are arranged to render service to telephone subscribers, a number of trunks are interposed between the two offices so that the subscribers in the communityidial area, for example, may communicate ,with subscribers in the area of the operator or master oiice. In an emergency it may happen that an urgent call must be made by one of the conimunity dial office subscribers to the operator at the operatory or master oice or to a subscriber in the latter area but all trunks between the two offices may be busy at that time. It is also possible that all links or switches in the lcommunity dial oiceare busy. In that event the urgent call must await the liberation of one of the several trunks or links or switches. Any such delay may perhaps be quite unfortunate;

In order to overcome the `tliliculty referred to, and to provide service in any such emergency, it is proposed to set up apparatus at the 4community dial office and at the operator or master oliice to enable a subscriber to seize one of V the trunks-which may be a preassigned trunk when the trunk is busy, interrupt whateverex isting service there may be over the seized trunk, and connect the subscribers set to thatV trunk. This arrangement will connect the subscriber to the operator at the master (orroperator) oice and so permit the subscriber .to communicate with the operator during the period of emergency.

In accordance with this invention lthe subscriber who is to be permitted to seize an assigned trunk will have a magneto generator connected to one of the conductors of his linewhich,wh en1op erated, will rire a gas tube at the dial office.V The ring of the gas tube will set certain relay apparatus into operation to interrupt existing servlamp or other indicating device may be employed l at the master cfce to apprisel the operator that a call is being made over the trunk. y

The proposed arrangement thus will give rightof-way to a subscriber at a time when all lines, links or switches are busy. The apparatus're- `cost and may be of value for use in emergency conditions.

master` or operator oice MO by a plurality of .trunks TKi, TK2.

There are in general more subscribers lines, such as SB1, extending to the `ofce CDO than there are trunks, 'such as TK1 between the oice CDO and the oce MO. It is well known in the art that any subscrbers line suchas SB; or SBz may be connected to any one ofl the trunks such as TKi or TKz through the equipment at the community dial oce CDO and ftliat signaling may take place over any one of the lines and any one of the trunks in tandem.

For example, when the telephone receiver TR of the subscribers set SS; is removed from its Shook, the line relay L at the community dial oice CDO will be operated over a circuit including battery, the upper winding of relay L, the upper armature and back contact of the cut-off relay CO,

thejupper conductor of the subscribers line SE1,

30 the pulsing contact PC of dial DL, the transmitter TT,' the switch-hook SH, the winding Pof the induction coil, the lower conductor of .line SBi,

`lthe lower armature and back contact of the cutoi relay CO, the lower winding of relay L, rectier Z and ground. VThe closure of the contact of relay L operates the line linder start circuit 'so -that va line finder (not shown) may be actuated to nd the calling line. As is well known, when the calling line is found, ground is applied to the sleeve contact S, whereupon the cut-oir lrelay CO becomes operated by the completion of ian ObviousY circuit. connects the windings of relay L from the callfing" subscribers line SBi. plied in a well known manner' through the line .'nder from4 its associated first selector (not The cut-01T relay CO dis- Dial tone is also apshown) to the subscribers line'SBi to'inclicate to the subscriber that the apparatus is ready for dialing. The subscriber may then dial the deysired number and talk over the line lindercrcuit for outgoing'calls, as is well known. The fout- `going call may be completed over. any one of the various trunks, such as TKiwhich may happen to be selected by the dialomcev equipment. f While quired to practice the invention is simple, of low 55 theVA subscribers line ,SBr may'be'connected to a trunk such as TKi, for example, other Subscribers lines may be connected to other trunks either for incoming or outgoing calls.

Suppose, however, that the dial DL of the subscribers set SSi is operated to dial or some` other preassigned code to reach the operator (at the master cnice MO). The dial office equipment will hunt over the group of trunks assigned to that level in a well-known manner and if all of the trunks or all switch paths are busy, the trunk hunting selector (not shown) will return a busy tone to the subscriber. Under such conditions it it possible to signal the operator in accordance with this invention by operating-a-handfgenerator MG at the local station. Thegenerator -MG controis a gas tube TB at the oilce CDO and other equipment employed for seizing a predetermined or preassigned trunk such as TK1, disconnecting all service over that trunk, and rendering the trunk busy to all parties except the one operating the hand generator MG. The subscribers telephone transmitter TT and receiver TR will be connected'to the trunk TK1 to enablethe subscriber to communicate with the operator or other desired party. This will now be explained in v greater detail.

The hand --or magneto vgenerator MGmay be operated by the subscriber while his receiver TR is retained on the switch-hook SH. When operated the generator MG supplies a lsubstantial alternating voltage to the upper or tip conductor T of line SBr, this alternating voltage being'applied over a circuit'including the upper armature of relay CO, the'control electrodes of tube TB, the battery KS, and ground. The alternating voltage of generator MG'and thevoltage of lbattery KS together are suicient'tore'the*tube TB, that is, to ionize the gas within tube TB. When tube TB 'is fired, the relay A will'be operated overa circuit which'includes battery KS, the left-hand winding of relay A, the anode and upper control electrode of tube TB, the'upper armature 'of relay CO, the upper or tip conductor T of line SB1,the generator MG and ground. As the left-handwinding of relay A becomesenergized to operate'the relay, relay A will'become'locked in its operated position over a circuit which includes the armature and contact of relay A, the right-hand winding of relay A, the makeebforebreak contact of relay C, the winding of relay B, battery and ground. Thus,v relay A will be operated in response tothe reception of the a1- ternating wave of generatorMG and it will be locked in its operated position.

It will be observed that the winding of relay B is included in the locking circuit of relay A. Consequently relay B will be operated in response to the operation of relay A. The opening of the back contacts of the three upper armatures of relay B will disconnect the trunk hunting selector multiple tip T, ring R and sleeve S arch from the trunk TK1. The uppermost armature of relay B will be connected to the tip T or upper conductor of the subscribers line SB1 and thereby establish a conductive path between the upper'or tip conductors of trunk 'IKi and line SBl. The next uppermost armature of relay B will`be connected throughthe winding of relay lC to the ring R or lower conductor of line SB1 and thereby establish a conductive path between the lower or ring conductors of trunk TKi and line SBi. The trunk TK1 will thus be electrically connected to the subscribers line SB1.

The closure of the contact of the lower inner armature of relay B in response to the voperation of relay B will apply ground to the sleeve arc S of the trunk hunting selector multiple so that this trunk TKi will test busy for all subsequent outgoing or incoming calls. This same ground will be applied to the upper terminal of the winding of the cut-oi relay CO, causing relay CO to operate. The operation of relay CO will remove the subscribers line S131 from the line finder start circuit and thus prevent actuating a line finder when the subscriber on line SBi removes his re- ,ceiver from the switch-hook. Ground on the sleeve conductor is also extended to the connector mul-tiple to prevent incoming calls from being completed over the subscribers line SB1. The two lower-outer armatures of relay B will dis.- connect-the incoming selector from the operators circuit (or other line circuit) connected to trunk 'IKi and interruptany call being made over this circuit.

The lower or ring conductor R of line SB1 is 'shown connected to the make contact of the upper intermediate'armature -of relay B through the winding of relayvC. While Arelay B remains operated, I current will `iiow `through the winding of -relay C to-hold it operated. Thearmature of relay -C applies ground to the winding of relay B to hold relay B operated. Inasmuch as relay C is 4of theslowrelease type, relay vC will hold relayrBoperated oven when the subscriber moves his-switch-hook SH `back and forth to ilash the operator. Moreover the operation of relay-Cwill open thelocking-.circuit of relay Aand allow relay `A to release without .causingrelay :B '.to release.

Ithasbeen :pointed out that Yby operating generator .MGfthe relay B becomes operated to Yinterconnect the subscribers line SB1 With-trunk TKl. Uponfthe completion of this-interconnected vcircuityrelayM'R at .the'master office NIO, which is-connected lto vtrunk TK1, will 'become operated because the winding of this relay is included in -the interconnected circuit. Upon the operation .of relay MR, the trunk lamp TL will be illuminated to attract the operators-attention. The operator lmay then insert lher 4plug P1 into jack J; toanswer .the call. The insertion :of plug'Pl into jack J1 will cause vrelay MR to release and thereby extinguish lam-p TL. At the same time the Winding of lthe supervisory relay SR of the operators cord circuit will be energized -and relaySRwill 4remain renergized as longas thereceiver TR at Vthe subscribersvset SS1 is removed from its switch-hook SH.

The winding of relay FR is included inseries with the sleeve contacts of VVplug P1 and jack fJ1.and resistanceY. Relay FR willfthereforebe operated .as .soon as the operator insertsher plug P1 into jack J1. If 'in the `meantime the subscriber moves ,his switch-'hook SH back 'and forth to attract the operatorsattention, the relay SR Willbe released when the circuit is brokenby the switch-hook SH and re-.operated when ,the circuit is recompl'eted. `When vthe lback contact of'relaySRkis closed upon the Vrelease of relaySR,`t`ne supervisory lamp `SL will beilluniinate'dfby lthe'completion .of a circuit whichincludes battery, lamp vSL, 'f the armatureandmake contactfof relay FR,`the 'armature an'dbac'kcon- -tactof relay SR and ground. Thelamp SL will be extinguished whenever relay .SR releases. Hence lamp [SL .will Ybe repeatedly flashed `lto notify the operator that ,the subscriber desires'to communicate with her. YThe ,operator of .course may connect thefsubscriber v.to any other party.

When ,lines .SBi and TK1 are interconnected las* alreadydescribed, the subscriber maytalk vto the operatoror to any other party connected to the line by the operator. The talking path is a normal two-way path from which alllpreviously connected lines have been disconnectedj The interconnected circuit is also held busy for all f will then be free for use by .any other subscriberi' subscriber a right-of-way not heretofore provided*` in telephone systems. The additional equipment required to practice the'invention is simple and readily available and its initial cost as well as the cost of maintenance are quite small. The

operation and control of the apparatus in re-' sponse to the subscribers manually operated generator MG is positive and free from any interference either by the operator or by the other subscribers. Moreover, the seizure of trunk TKi is accompanied by secrecy in that all other subscribers of the omce CDO are disconnected from trunk 'IKi and cannot hear the conversation thereover. The value of the arrangement during emergencies is considerable. Because of its simplicity the arrangement can be easily` applied to many types of telephone systems with very little modification.

Although the magneto generator MG is shown connected to one of the conductors of the subscribers line SBi, it does not vary the impedance of the line or affect transmission over the line while it is unoperated. As is well known the magneto-generator becomes effectively connected to the line only during the timein which the crank handle is rotated by the subscriber. Although the generator is associated with the subscribers set SSi, similar generators may be associated with other of the subscribers sets, but each such generator will require apparatus to respond to the generated current to interrupt service over other of the trunks and at the same time to render the interconnected lines and trunks assigned for seizure busy Although gas tube TB is also connected to the subscribers line SBi, the tube has no effect upon transmission until the gas enclosed within its envelope becomes ionized. The gas becomes deionized as soon as the crank of the generator is stopped.

The device Z is inserted in series with the winding of line relay L so that only unidirectional current may flow therethrough. Because of its unidirectional characteristic, alternate halves of the current generated by the magneto device MG will traverse the device Z. The device Z will therefore substantially reduce any flutter of the armature of relay L and prevent false operation of the apparatus controlled by the relay L. The device Z will also serve to conne practically all of the generated alternating voltage to the gas tube TB to aid in ring the tube. Any well known ,of the appended claims.

rectieror-varistor may be used for this purpose. A thermistor may lalso be used for this purpose, but the thermistor will operateto reduce :flutter by means' of its slow-actingcharacteristic.

The gas tube TB is shown connected to the tip conductor Tlof line SB1 between the upper armature ofrelay CO and the upper Winding of relay L. The Itube is therefore disconnected from the generator MG after the relay CO has operated to prevent its occasional false operation. If desired, the tube may be connected between the upper or tip conductor T of line SB1 and the upper armature of relay CO` In the latter position thetube will be connected to generator MG even after relay CO has operated.

. Although this invention hasv been shown. and

described in: certain particular arrangements merely for illustrative purposes, it willbeunderstood that thisinvention may be appliedto other and widely varied organizations Without departing fromthe spirit of the invention and the scope What is, claimed is: Y

1. The combination of a central ofce, 2 rst subscribers circuit connected by a telephone `lirie to the central cnice, a second subscribers circuit, means for enabling the second subscriber to'seiz'e the telephone line extending to the'rst subscriber, said means including a gas tube Vat the central office, means controlled 'by the4 second subscriber to re the gas tube, and means responsive to the firing of the gas tube to discon nect the iirst subscribers circuit from the telephone line and substitute the second subscribers circuit therefor.

2. The combination of two telephone oiiices, a .plurality of trunks interconnecting said oiices, means for enabling a subscriber to one of said offices to communicate with the other oiice over a predetermined one of said trunks, said means comprising a generator to be operated by said subscriber, a gas tube connected to said generator and fired when said generator is operated, and means including a relay responsive to the firing of said tube to seize said predetermined trunk and to interrupt all other service over said trunk.

3. The combination of an operator cnice, an auxiliary ollce, a trunk interconnecting said offices to Which telephone subscribers may have access, a gas tube, means to re said gas tube and seize said trunk to preempt it for use by a particular subscriber, said means including means to interrupt service by all other subscribers over said trunk.

4. The combination of a main oce, an auxiliary office, a line interconnecting said omces,

n means for preempting service over said line, said preempting means including a gas tube, and means responsive to the firing of said tube to interrupt any existing communication over said line.

5. The combination of two telephone omces interconnected by a line over which communication normally takes place, a gas tube, a relay controlled by said tube to interrupt service over said line, and means for firing said tube.

6. 'I'he combination of two telephone oices interconnected by a line which is available to numerous subscribers of said offices for communication purposes, means for interrupting any existing service over said line and seizing it for use by a particular subscriber, said means comprising a source of potential, a relay controlling said line, and means including a gas tube respon...

-sive .to the potential .-of fsad source ,ffor iiringzsaid gas tube and -operating saidrelay.

7. The combination l'oifan yoperator cnice, an auxiliary office, -a -.trunk -line extending wto rsaid operator cnice, ya plurality fof subscribers lines each of whichz'may ,Abe connected :to said .trunk line, Vmea-ns to .fenable a :subscriber :to seize said trunk -line wheniit Ais busy ,and connect Ahis own line thereto, :said means :including :afsource ,of voltage supplied from fone of said subscribers lines,:a `gas :tube controlled. by said sourcefof voltage, and means controlled-'by said ggasftube to render said trunk .line V:busy :to `:all :subscribe-rs .lines except the subscribers iline which `:supplies said source of voltage.

`8.In a signaling system, .the .combination of rst .and second stations connected -to eachother by aflineso as to v'be :in communications with each other, sa ,third ystation,means'ito connect said lsaid potential to interrupt communication between said 'first and secondstations.

'9. In a signaling system, the combination of a .central station, aplurality o'f auxiliary stations, a line terminating Vatsaid central station, means for connecting any ,one of said auxiliary stations to -Vsaidlineto establish communication With thevcentral station, means at one of said auxiliary stations lfor seizing said line for communication vto said central station, said means including meansfor producing-a potential of predetermined magnitude and means responsive to said potential for interrupting `communication over said line and forpreventing any of the other auxiliary .stations from being connected to said line.

r1.0. The combination of Va plurality of trunks interconnecting two telephone oices, means for seizing a predetermined one of said trunks whether :or not thatitrunk .or all other trunks are vlousyfsaid `means comprising a source of voltage,

algas tubecontrolledby the voltage of said source,

yand vapparatus controlled by saidgas tube to seize said Ipredetermined trunk.

11. The "combination of two 'oilices connected to each other bya line for signaling purposes, said line being available to various parties at lsaid ofces for signaling purposes, means for preempting said line to render said line available for special service with lprivacy whether or not said line 'is busy, said means including a gas tube, means to fire said gas tube, and means responsive to .theflring of said gas tube topreempt said line for said special service.

CHARLES STANLEY RHOADS.

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