US1901403A - Telephone system - Google Patents

Description

March 14, 1933. P. B. MURPHY TELEPHONE SYSTEM Original Filed Dec. 6, 1950 4 Sheets-Sheet 1 GE mat Nut .0 6t

INVENTOR RRMURPHV A TTORNEV March 14, 1933. P B MURPHY 1,901,403

TELEPHONE SYSTEM Original Filed Dec. 6, 1930 4 Sheets-Sheet 2 MARG/NAL #vmvrop RRMURPH) er Wfi f ATTORNEY March 14, 1933. P. B. MURPHY TELEPHONE SYSTEM Original Filed Dec. 6, 1950 4 Sheets-Sheet 3 //v VE/V r0)? I P a MURPHY WWV A TTORNEV March 14, 1933. MURPHY 1,901,403

TELEPHONE SYSTEM Original Filed Dec. 6, 1930 4 Sheets-Sheet 4 IN VE N TOR v St RRMURPHV 7 ATTORNE Famed lVlar. i4, 193s U ITED STATES ran s. mIBrHY, or nYAcx, nEwYonK, AssieNon. TOCQBVELIQ- 'rnLnrironnjnanonn roams, mcoarom'ran, or NEW renx, n.1, A coR-Poan'rIoN or Nnwromz;

TELEPHONE SYSTEM Application filed December 6, 1930, semi No.-oo,517.- Renewed April 157193211 {This invention relates to telephone systems andparticularly to means for checking .ilcalling subscribers numbers and the object of the inventionisto simplify and improve the/checking of numbers when applied to automatic systems.

VHeretofore systems have been proposed in whichan' operator atone office maycheck vthe-number given by a calling subscriber at another oflice who hasestablished automaticallya connection to said operator over a trunkbetween said ofiices by establishing a separate connection to the calling subscribers. lineand causing the application of an alter- 11,5

nating currentsignal through the automatic connection for detection by this operator f the calling subscriber gave the correct-num- -ber.- ,A system of this character has been" disclosed 'in :the copending application of R L. Quass, Serial No. 500,492, filed'on the same .date with this application. In the Quass system this alternating current signal applied from means inthe second connection."

by the operator atthe second oflice causes the alternatingcurrent signal to be applied to the automatic connection by transmission of adirect current signal over the trunk line of theautomatic connection from the second office to thefirst .ofiice' and by having this direct current signal, when receivedat the ifirstioflice,translated into the alternating current signal for transmission over aportion of the automatic connection at the first office specific feature of this arrange- ;.ment 'f or applying the alternating current signal is the means for applying the direct current signal over the trunk when this trunk is of the type in which the usual supervisory 1 signaling is done in one direction by reversal of battery and ground connections over the tip and-ring conductors and in the 5other direction by the reduction of resistance of this battery and ground connection fover the tip and ringconductors. This direct currentsignal may .be applied regardless of whether or not .the battery and ground. connections have'been reversed. A differen i 1 1 g Fig. 1 show ;a modified A feature of the present invention is an 1 arrangement in systems of this kind'where-c tially wound relay is providedat thelfirst ofiice for the application of the alternating current signal This relay-is providedwithtwo windings connected in aseriesopposing direction from battery to fground through .the tip and ring conductors to jpr'event said relay from operatingin said, circuit regard- PATENT less of the current reversals,-and a circuit arrangement is provided whereby regardless of the current reversalsa connection is made;

at the first office from a battery of ahigher voltage than the normal battery-in opposition to said normal battery to cause the di rect current signal therefrom"v to operate.

said relay to apply the alternating current signal.

This invention has been illustratedthe accompanying drawings 'in which 7 Figs. 1'00 5 may be arranged as shown in Fig.6; v V j; Figs, 1, 2 and 3 show ascomplete system for number checking; while a l Figs. 4 and 5-taken in connection with" scriber 1 at office A-may. extend an automatic connection to atoll operators posi number checking tion-TO at oflice B over; a line finder LF, a

selector S and a district selector DS and a trunk ST. The circuits at thejcall-originat-. mg end of trunk ST have been shown in Fig. 1 in detail to illustrate certain features of the invention and the circuits for this trunk at the toll ofli'ceB have also been shown in detail in Fig. 2 to illustrate other features of theinvention. Trunk ST-ter- 301- to a desired line. ,A number; checking cord 302 hasalso been shownin Fig.3 in

.minates in jack 200 at the tolloper'ators podiagrammaticform. This cord may be used for checking a calling sub'scribers number over the number checkingtrunk-NGT that" This number checking trunk NCT termi.-

terminates at the toll office B in jack; 201.1:

ing snbscr-ihe-fls number over the checking w terminal 105 which is connected -to-the-sleeve The circ,uit,,details of theinumber checking Cora-ace: and? trunk NCT? {and the A j0vperators cord have not been shown as these details do not appear to be necessary-for the clear understanding of the present invention and inifact any w-ellek-nown means may be toll operator andthe A operator in regard to her-checking. Theniodified for-in of the employed for communication between the invention as shown in Figs. 4 and 5 shows a -;I-IIOQl l fiCZL tlODOZE the circu ts of, trunk S1 at ithe"terminating--end in the-toll; ofiice B and 'erators p'osition :for causinge' 'the number by the subscriber at '1 to the toll operator at TO- an-dthe establishing of another con nection "from the toll operator TO to the A :operatorA O' for the checking of'the calling 1 checking signal-to be effected.- I

A -d'escript:ion" will now be made using Figs. 1,2 and of a connection vestablished subscriber-snumber,- I

Atter the calling subscriber at l has establis'he'd a connection over line-finder 'LF,

selector Sand district selector DS to trunk '-S':1- of :any well now-n automatic system, a

circuit is established for the operati'on-of relay-l07 as follows: battery, uppe'r outer armature and back'contact of relay 108,'repe'ating'coil'1'09, upper armature and back contact of relay 110 over thetip conductor through a loop connection in the district" -iselector DS, back over thering conductor, 1

---lower inner armature and back contact of re'l'ay 110, repeating coil 1'09, upper inner armature and back contact of'rela y 108, up-

perwinding ofrelay 107 to ground. Relay 107 in'operatingrcloses a circuit for the op-- eration of relay 111 from battery, winding I of. relay 111, make=before break contacts of relay 112; armature and i'ront contact? of relay :10? to ground. 'Relay 111' in op-- crating partially prepares a supervisory signaling circuit over trunkIST. it also es-' *tablish'es a connection to ground overits lower middle armature and i ront contact, JIIlZlkG-bGfODG lJIGfik contacts of rel ay 2113,0011 "-1 26, 'tothe sleeve conductor 'o'f th'e district selector to maintain it busy. 'An obvious T circuit is also prepared for the operation v ofrelay 113. This relay' fin operating, sup- "closes an obvious circuit ifor the operationof of the 200.

relay 115. This relay closes a ringing induction connection from the ringing source 121 to the calling subscribers line. This relay also extends a connection from battery and ground through windings of relays 116 and 117:, arn atures of relays: .11 5, and ;111, re-

*peatin 'coil ltll trunk ST arniatures and conductor of the calling subscribers. line... b

,backconta-cts of relay 203, repeating coil 204;, arn atures and back contactsoff relay '205 tl1ro'ujgh'" a loop over thewindings of relay- 206; L'Rela'y 116 'd'oesnot operate in this circuit-as it is differentially wound and provided for number checking purposes as will E:be hereinafterdescribed1;.Neither does relay 117 operate in this circuit due to the high resista-nce'of the lower winding of relay 206 and the marginal "characteristics- 0f relay 117. Relay 206; however, 'operates and "closes a circuit for the operation of relay 207; Ground is disconnected from the -low resistance windings of relays 208 and 209 by the operation of "relay 206 andthe purpose iof this will be described in 'a connection recalling th'e tol-l operator from the sub- I scribers station: The operation :01 relay 207:

clos'esfan obviou's' circuit for the operation line la rnpassociated with ack The toll operator" at" .TQ ans-wers this signal 1 by "inserting the answering pl ug 211 of cord-300in'to jack 200. -The immediate effect of this connection 'wi ll b'e' the-operation of relays 208 and 209 from a--"-battery'= supplied over: the sleeve of cord 300130 the upper windings of these relaysto 'ground; -Relay QOSf-inopei'ating, closes an obvious circuit for the"'operation' of relay i 212; {Relay 212, in operating, opens "the circuit for-the line lamp 210 atits lower outer armature-and -"back"'con='tact. -R'elay 212 also completes acir'cuit for the windin'go f relay '205and resistance-213 tobattery at the lower outer armature and front contact or relay 212. "The operation of relay 205is, however, we ventedfdue to the ground shunt connection atthearinature -and front contact ofrelay 209. 'The tip and ring conductors cs f Fthe trunk ST' are-now connected through the cond'enser 214 "at the flipper armature-and frontron-tact of relay-212 to pr'oifide a talk-' 'ing"cir'cui t'.' Relay 2'12-also*s'lruntsatits lower inner armature and front "contact the lower high reSiStaI-I'ce winding of relay 206. Relay 200,1liowever,"-rernains operated. At the call-originatingend of trunk'."- ST, the marginal relay 1'17 nowbpe'rate's due to the shunting or the high resistance Winding of relay 206. Relay 117inbper'ating closes an obvious circuit for the operation of relay 120. Relay 120, in "operating; ope nsfthe ringing induction connection from the ringsource'121' to th'e calling s'ubscr'ibefis line at it'supper armature, andjbackfcontact. "IRe "lay 120 also closes an 'lobyiousj" circuit for rela -113 to "hold this relay operated to and ground connections over .the tip and ring conductor tothe district selector DS to cut throughby meansin the district selector (not shown), the tip and ring connection from the callingsubscribers line tothe relay 107 It, will be noted thatthe talking con-- nection .from the callingsubscribers line now extends-through both windingsof relay 107 and that relay 108 has closed at'its lower outer armature and front contact the talking connection through the outgoing coil, of the. V repeating .coil- 109'. The circuitsare now incondition for conversation betweenthe-subscriber at 1 and the toll operator at T0.-

If the calling subscribersdecides to recall.

0 the toll operator at T0 he will operate the switchhook in the usual manner. causes the alternateloperation and release of relay 107. Relay 111 being under control of relay 107 will follow these operations and 7. cause the battery and ground connections -operator at T0 that the calling subscriber- -the calling subscriber she will operate the ate relay 110 over an obvious circuit, the ground connection for which is supplied 50. throughthe armature and front contact of r a locking circuit for itself under'control of over trunk ST to be alternately reversed. This causes the alternate release and opera-V tion ofrelay 206. Relay 206,*in turn,willl alternately connect and disconnect the ground from the lower windings of relays 208 and209. This'will have'the efiect of alternately lowering the resistance in the sleeve circuit-for cord 300 and thereby cause inany well-known'manner the flashing of a supervisory lamp-in this cord to notify the desires further attention. 7

If the toll operator at T0 desires tor'ecall usual ringing key in cord 300 (not shown) and thereby cause the ringing relay'203'to be operated and apply ringing current from source 214 over the tip and ring conductors of trunk ST to actuate the ringing respon sive relay 123. Ringing relay 123 will operrelay 107. Relay 110, in operating, provides relay 11 1 independent of relay 107 and supplies'ringing current to the calling subscribers line from source 125' and the ground return at the upper armature andfront contact ofrelay 1-10.' It will be noted that onthe operation of-relay 110 relay 107 willrelease but relay 111 will now be maintained operated under control of relay 114 over a circuit through the lower outer armature relays 123 and110. Relay110 in releasing This again closes a circuit for'the operation of relay-5107.

After the calling subscriber instructed the toll operatorat toextend a connection to a desired 'subscribers lineand this connection has beenmade and conversation completed the calling. subscribermay dis,-

connect ,by replacing; his receiver on the hook.j This causes the release of relay 107 which in turn causes: the release of relay 111:. T Relay11'1, in releasing, releases'relay 2,06to 1 continuously "light thev supervisory lamp. in

the cord, 300 as a disconnect signal. The

operator at T0; will now disconnect: by removing plug 211 from jack 200 therebycausing thee-release jof relays 208 and 209'.vv .,-Relay 208, in releasing, causes the release of relay 212- and this-relay in turnremoves the short circuit from the lower high resistance winding of relay 206 thereby, causing the release of relay 117- which, inturn, causes the releaseofrelay 120. Relay --120,'in releasing, opens the circuit for relay 113; which, in releasing, releases relay 11 1., The release of these relays opens the connection to ground for the sleeve circuit-tothe district selector and causes the release ofthis selector and the preceding switchesinthe connection to the" calling subscriber Relay .11 1 releases relays 108 and. 115 andthecircuits shown in these zfigures are thereby returned to normal condition.-'- Ifthe toll operator; at TOishould disconnect before the calling subscriber, relays 208-, 209 and 212 will release and thereby cause thelighting of the line lamp 210. x

;The operation of these, circuits while checking the calling subscribers' number will nowbe described. Thetoll operator will first, by operatingher-talking key in cord 300, (not shown) connect her telephone set 303 through cord 300 to the calling subscribers line and secure ,the number of this subscriber for the purposeofchecking it as wellas for the securingof theinformation for extending the connection of thegdesired subscriberifiline When the operator has received :the number ofthe {call-ing subs'c'riber, she-will actuate a talking key (not shown) in the number checking cord 302." Theoperation' of this key, connects the telephone operators set .303 with plug 309 for number checking; -The,..toll"operator will 5 checking trunk NCT and operate key3l0.

tion of relay 311. Relay 311 in operating its a now insert plug 309 into jack 201 of a number armature opens the sleeve circuit'for the cord 300 and establishes a connection from a batterypthrough this armature and its front con tact to thesleeve of cord 300 leading through plug 211 to trunk ST and also at the makeand front contact of relay 110. When the operator at T0 discontinue's the ringing re; 65 lay 203 will release to cause the release of" before-break contacts controlled by thisarmature closes a circuit to ground for the will be noted that the circuit train batter forthe sleeve circuit to the trunk ST {passes through a resistance {312. During the -oper-' ationof relay 31 1, the sleeve circuit to the V trunk was momentarily interrupted which caused-the release of relays 208 and 209 mo-' mentarily; \Vhen the above-mentioned cir- V cuit through resistance 312 is closed, relay 208 will again operate, w-hi le] relay 209 which is-inargin al will remain released due to the high resistance 312, inthe sleeve'circui't. During the momentary release of re lay 208, the circuit for relay 212 was opened but this relay is slow in releasingso-that it resistance 21-3 causes the operation of this relay. Relay 205, 'in operating, disconnects the relay 206 from the trunk ST and thereby causes it to release. If relay 207 is operated at this time,iit will be held operated by the operation of relay 205 througha locking "circuit provided at the lower armature and these circumstances when relay 205 operates, high voltage battery and ground will be 7 supplied to the line as follows: from bat-l tery and ground through the windings of retardation coil-'216-, a r-matures and front contacts of relay 207,- ar-matures and front. contacts of relay 205, transformer 204?, armatures and back contact of relay 203,'tip-and; ring conductors of trunk ST. The high,

voltage battery will be connected injthis case over the ring concluctorof trunk ST to the' battery through a winding of relay 116 i to ground, while ground at 21 6 will he connected to the tip conductor to ground at 'ated-at this time, the high voltagebattery would have been'connected overth-e tip con ductorand in this case the relay111 would not have been-operated so the connection would have been made to thesa'rn'e battery at relay 116. This arrangement is for the. a purpose o -f insuring the operation "of relay 1 116 regardless of whether supervision is being carriedon during this time or not. That is, regardless howthe tip and ring conductors are connected for supervisory signaling as-hereinbetore described the battery at 216 will always be switched to oppose the battery at 116 when number checking sig-V In either case, there- 0 naling takes place. fore, relay 116 will-be operated as it is differentially wound and'the high voltage battery causes current to flowthroughawind.

7 ing of relay 116 inthe opposite direction to age battery. Relay 116,in operating, closes an obvious circuitfor ,theoper'ation ofirelay 112 and this relay in operating provides a a holding circuit for-relay 1-20if it has been i operated byrelayll'f during supervision.

will remain operated during this period.- As relay 209 is-now released the circuit here: inbeiore mentioned for relay 205 through front contactto ground of relay 205. UnderI relay 116. If relay 207 had not beeno'perthat ordinarily flowing from the low voltino-1 ,463

If relay 117 was not ope'rated,re lay 120 will now be operated by-i'e'lay :112'to maintain the circuit connections established regardl ess ofw'hether relays-117 and-111 are operat'ed or releasedduring the number T check- ,in-g' period; Relay 112,in operating-"provides a connecti'on from an alternating current source 126 totl'ie sleeve of the connection to thercalling'subscriber 'a'ndvthe extension sleeveof' the callin subscriberv'to vnumber"checkingterminalxjmo.i' f a "While this numberichecking signal being transinitted,'the tOlilz'OP'QIELtOI' will infformbthe LA operator at position A0 of the number iofthe 'cazlling subscriber. The num: 'ber checking trunk may: betany well-known communicating circuit in which the inserti'oniof .plug 309 into jack-1201 '7 causes the operator at AO -to' be called and when this operatoranswers thecal'l 'hy iiisertingr the-' answering plug of cord 101 into jack 101 a talking connection is "established between the two 'operatorsp The A operator will then receive the number of'the subscriber whose-number has to-be checked. 'She will then touch the checking terminal, 105 which is marked with the numberof the calling subscriber .withsthe tip of the ical'ling plug :of cord 104. This terminal may lee-mounted on the. A operators board for numb er che'ckangU-purposes'in connection with similar terminalsof-other lines that may be checked in this manner by the operator. If an alterhating current signal is detected on the sleeveconnectionirom source 126 the-A operator will know that-the number given by the callingsubscribe-rwas correct; The A operator will then communicaterwith the toll operator andv inform her that the numbe-r given by the calling subscriberiw'a's the:

correct number. If, however, tl ejA operator does not receive an alternating current signal on terminal 105 she Will know that the calling subscriber gave the wrongnumber as the terminal 105 would in that case ;be associated with another ,subscribers over the connection established between the atoll operator and the calling subscriber and in-regard to the'passing of the alternating current signal toythe-caglling subscribers sleeve; g

In signaling from the calling subscribers line over trunk, ST relay 406 operates through both windings being, included in the tip and ring connection; Relay-407 is then operated overan obvious 'circuitto prepare the circuits for numbei ghec'king. Re-

lay 406, operating, also closes an obvious circuit forthe operation of relay 408. This relay, in operating, closes a circuit for the.

telephone set 503 'to be connected to plug 508 for number checking' When cord'500 was connectedto jack 400 relay 412-,was

operated from battery over the sleeve of the cord to extinguish'lamp- 410,to establish a talking circuit and-to short circuit the high resistance winding" of relay 400; This causes the operation of the relay 117, Fig. 1, and

the operation of the circuit in Fig. 1 is the same as hereinbefore described in connection with Figs. 2 and 3. i

If thecallingsubscriber desires to recallthe toll ope rator at TO, he will proceed as 'hereinbei'ore descri-bed'to cause the alternate operation and release of relay 406 which, in turn, causes thealternate operation and release of relay 408. Batteryand ground are thereby alternately connected to the tip conductor to flash the supervisorylamp in the 'cord" 500.. Relay 417 is 'not'operatedfi during supervision regardless of whether re- V lav 408 is operated or not as it isditferentially' wound.

Iffthe toll I calling subscriber, she causes alternating current to be applied from the cord 500 to operate the alternating current responsive relay 420 and thereby cause the operation of relay 403 to apply ringing current over the trunk ST and thereby call the calling subscriber in the samemanner as'hereinbe: fore described in connection with Fig. 1.

The toll operator, in number'checking," inserts plug 508 into jack 401 and operatesa key (not shown) to connecther telephone set 503 with trunk-NGT. She-then notifies the A o-peratorthat number checking is desired and operates key 510. 'The opera tion of this l'keycauses the operation of relay 511. Relay 511, in operating applies a ground connection througha retardation coil 512 to the tip and ring conductors of the. cord 500. This'is the essential difference fromthe signaling caused 'byffthe op eration of relay 311, Fig, This ground connection onthe two conductors causes the operation of relay 417 regardless of whether relay 408 is operated or not. Ifg'round is connected to the upper winding of relay 417 when nuinb'er checking, this" winding is shunted and thereby permits current through the lower winding to cause the operation of this relay, while if battery is connected when number checking, the curvoperator wishes to recall the rent in both windings aid each other toe cause the operation of'this relay; Thus 1 number'checking operations are not interfered with by supervisory signaling. f Relay 417 in operating, closes a circuit forthe 'operationof relay 405 to apply battery and groundthrough the retardation coil 416 and contacts of relays 407 and 405 to the distant end of the trunk ST to cause the operation of relay 116. In this'case, it depends upon the operation of relay 407 whether battery or ground should be connected in one way or another tothe tip and ring conductors.

Relay 116 applies the alternating current signal to the sleeve conductor ofthe calling subscriber'a's herei-nbefore described. hen the number" checking has been completed and lamp 516-"has been lighted steadily or flashed depending upon-whether the sub scriber gave the .right nu'mber or not, the toll operator removes plug 508 from jack 401 and proceeds with thesetting up of the a connection. g

While this invention 'haso'nly been described in connection with two systems it should be understood that it can readily be applied to other systems withoutdeparting from the spirit thereof and that the presentdisclosures are merely illustrative of the invention-n v 7 What is'clanned 1s:

a '1. In a telephone"fsyste1n, a first oiiice a second oflice, a subscribers line at the first ofiice, means for establishing a connection 5 from the subscribers line to the operators office, an operators position at the second positionfmeans for establishing a second connection from the operators'position to the subscribersline, means for transmitting a'direct current signal from theoperato'rs position toward the subscribers line, and means for translating-said direct current signal into an alternating current signal for transmission over said connections.

2. In a telephone system, a first oifice, a second oilice, a subscribers' line 'atgthe first oflice,an*operators position at the second oflice, means for, establishing, a connection from'th'e subscribers line to the operators position, said connection including a sleeve conductor forthat portion thereof that is located at the first oflice', means for estab-' lishing a'secondfconn'ection from the operators position tothe subscribers line, means for transmitting a direct current signal from the operators position' over the first connection toward the firstv office, meansjfor translating said direct current signal into an alternating current signahfand means for transmitting said, alternating current signal over the sleeve conductor of saidfirst connection to the second-connection.

3. In atelephone system,-a first oifice, a

second .oifice; a subs-cribers 'line at the first ofiice, an operators po'sition at the second has been reversediornotp 5. In a signaling system,'a.l1ne, a source of current for said'line, a seriesjconneot on ofiice, a trunk between said oflices, means q for establishing. a connection from the subscribers line over said trunkto said oper ators position, means for establishing a;

second connection from the operatorsp.osi. tion to the subscribers line,- adirect. current source associatedwith said'trunklwhile ens-- gaged 111 said first connection, means for signaling in either d rection over said trunk.

While, engaged in said first connection through reversal of the direct current from said source and chan es in the resistance. of

said trunk, means For transmitt-ing froin said operator s position a directcurrent signal over said trunk of a higher voltage than the direct current from the source associated Withsaid trunk regardless. of the-- direction of said direct current froinsaid source, means includinga relay at the first oilice responsive to the high voltage direct, current signal, and means respons ve to the operation of saidrelayfor transmitting an alternating current signal over saidconnections at the first office.

4. In a signalingsystem, a line a source of current for said line, means, for. signaling in either direction over said. line with the current reversed fromthe normal direction of said current'on said line, another source of current of a higher voltage'than the normal current on saidline, and means for signaling in one direction over said 'line with said increased current regardlessof Whether the direction of the normal current over the tip and .ring conductors of said line: from saidsource to ground, means-forsignaling over said linein-one directionyby revers n the current flowiithrou hsaid cone ductors i from said source, .means for signals ing over said lineinthe-opposite direct-ion by reversing the current from said source, and reducing the resistance of .said, connection, a relay in said connection,.means-for preventing the operationoisaid-relay regardless of the direction of the: current from said source in said connectiomasourceofi current of a higher voltage than .the current; from the firstmentioned source on said 11116,.

means for actuating said relay on the connection ofsaid second-source of current to:

said line regardlessofthe direction of the original current from the firstmentioned source. through said connection.

6. In a signaling system, two ofiiccs, a. line betweensaid oflices having a sleeve conduc-, tor at one oilice, a source of current-at one oilice for said line, means for signaling in either direction overthe tip. and ring conductors of saidv line with. the current-me versed from the normal direction 1 of said current on the said line,.a polar zed relay in said line at one ofiice, meansfomnaintain.

Lemma ing'saidrelay in non-operated condition res gardless of the direction of the current on.

said line, means including a source of cure rentv of. a higher voltage than. the normal source of currentat the othenoiiice for actu-.- atin said relay vreg mrdless. of the direction of I the normal-currentpn saidline, a. source. of-alternatingcurrent,and means responsive 1 to the actuation ofsaid relayfor connecting.

said source of alternating current tov said sleeve conductor for theiransmission ofa,

signal from said source over saidsleeve cone ductaor.-,.

7 In; a signaling system, a. line,,means for signaling in eitherdirection over said line in response to a: current impulse, and. means for signaling in onedirection of said. line in response to a; current impulse of] 'hi-ghervoltage:

8. In a signaling system, a line, means:

for signaling in one direction over said'line in response to a current impulse ofa certain voltage, means for signaling in the opposite direction over'said line in response to: acurrent impulse of the samevoltage. and

reduced resistanceofthe line, and means for signaling in one direction over. the line 1nv response to av current impulse of: another voltage.

9. Ina signaling. system, a line, ,means for signaling ineither direction lover said line in response to a current impulse and: means for signaling in one direction-overv said line in response to a current impulse of a higher voltageregardless of the presence at theti ne when this last mentioned signal-v.

ing is initiated vof either of the. other signals on the line.

10. In a signaling, system, a line, .means. for 'signaling in either direction over-said line'in response to. a currentv impulse, and means for disabling sa-id'signaling in either. direction-for signaling in one direction over said :line in response. to another current .impulse. r

11. In .a signaling system, a .line,la .source.

of vcurrentnormally connected to: said I line,

means forsignaling inqone. direction over saidlineinresponse to an impulse from said: current source of a certain polarity, means fox-signaling in theoppositedirection over. said line in response to a current impulse. from said source. of said. certain polarity RAUL B- P Y;

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