US2619528A - Selective signaling system - Google Patents

Description

Nov. 25, 1952 VROQM SELECTIVE SIGNALINGSYSTEM 2 SHEETS-SHEET 1 Filed Aug. 15, 1950 IN [/6 N TOR E. moo/4 ATTORNEY 2 SHEETS-SHEET 2 Nov. 25, 1952 E. vRooM SELECTIVE SIGNALING SYSTEM Filed Aug. 15, 1950 Patented Nov. 25, 1952 PATENT ()sEFldiEi.

SELECTIVE SIGNALING SYSTEMT Edwardifva'o'om, Ossiixing, Nu Y2," assignor to aBelll Telephone"; liaboratories Incorporated New? Yorke-NeY a -corporation of New York Application Aug stfi, 1950; Serial No. 179M15- ioiolaimss (01. 117-353)- 15. Thisiiiinvention:relates to:a -se1e'ctiveesignalinge system :andJmorei particularlm to apparatus op' erable only inresponse to the --rec.eipt of a-repre-. sent'ation: ofjthe: designation of that"aapparatiisa- An object-sot this: invention: is. the rapid and accurate *iascertainment; of ..'the arece'ipt' of aselected: one" ofz'a! plurality;- of: designations;

The: invention 1' may: 'find iapplicatiom inmany=- fildSiOf .communicationrsuch as :in t'elephone' ors' telegraph; ,switch'ingiisystems; mobile n radio sys} temsgz shipr-to shore co'mrmmication systemsy train. disp''atchingtlsystems, etc; Siich systems normally comprisesaz pli'irality: of terminatin'g or called: stations each-50f; which is suitably {deseignatedjbyaanumbenxatseries of .letterspor a'comhinationyof; numbers'x and letters;- In: order to establish: a: communication path '5 to a particular: oneiof: such: called; stations,v it is anormally 'neces sary for the called party to be informed audiblyand/or 'visuallyethat he islbeing called. Howeven: int-many :systems; the signals representin gaalargeigroup oiliiesignations-are received 'bycach ofiithes: stations. Consequently, it. is desirablethat means bezprovidedto alertlthe-called party only when his particular: designation is received? Therefore; inrgeneraLf; thisl'inventioncomprises aysystemsoperahle in response tog-the receipt 'ofag preselectedmneeonly ofzra" pluralit ylsof composite: signals to --energize a visual; oniaudibl'e signali aefeaturexson the. invention isxthejeutilizatiom of cold} cathode gaseouszdischarge; stepping de'vices each; having gar plurality :ofzcathodes. Y

Anothen: feature jofzithis'iinvention'. i's'"the provisionlof one:multicathodeigaseous dischargetic vicedforeach z'digit orrelement sofiiithezsubscribers 351 designationsn, I 1 Another feature of thiss'invention is: a means: for: successively operating ,thezmulticathode gaseousdischarge-devicesi only if eachxof the -succes=- A siveldigits or elements: received correspond with" the; elementon digit. at: thatiipoint in? the se*-- quence in; the designation; of; the: station; with w'hiizhthe {apparatus is associated;

' Theprinciplesof the inyentionrm'ay -be: more fiillij understood from the-Efollowing jdetailed-.,lfiea 4:5a scriptiong of I a? preierred embodiments. thereof when", read- "with, retrence to; .thdtacdompanizing: drawings, in. which: v

efl ista elevatiqnal view ofaaz-multicathodez glowdischarge; device-illizstratiyeebf: one :type M tuliensuitablefor; user-in the 1 presents-system Fig. 21s asectional view taken-along;::2-"-L-2 of Eige. 1 illustrating the arrangement oil the "sev eral "cathodes ,andfthe cooperative .relationithere'e of with the anode, 1 a 7 portion ofz'ftheranodesheingg 55'.

broken away to: show. certain; of; the. cathodes.

morei'clearly;;;andi:

Fig: 3 is la'rcircuit' "diagram representing; ai'pre-e' ferred; ambodiment' of the: invention:

The :multicathode'; stepping-"tubes. which are: employed: in the present system may be ofz'anyxsuitable: type;. A, tubeiqoperableiin.agsuitablea manner isdisclosedQfor example; in United States: Patent 2,575,370 granted November 20,.19'51; to]: M. A; Townsendathe disclosureof whichfis incorporated-herein hyigreference.- A:' represent'a'f-i: tion-of;v thatv tubeis; presented as. Figs. 1 and: 2,:..'of;: the present disclosure.

In. general, the disclosed gaseous: discharge -de'- vice, comprises an anode "and a plurality: ofv cold; cathodes in cooperative'relationship with the-an ode; the cathodes -.being mounted inarow which may Ice-rectilinear,circular OIfOf' other geomete: ricalt form. The-cathodes; or certain of-"them; are electricallygrouped and are=soconstructedz and arranged that i the discharge between one. cathode and the anode may be stepped or shift edselectively to-- a :path between the anode? and another cathode in response to signahpulses; the discharge shifting or advancing one. position for; each pulse.

Referring now to 'Figs.-1 and'2 of the drawings the tube of the exemplary type comprises a nplu rality of cathodes; l l,- hereinafter referred; :to as Ai cathodes, anda second plurality of cathodes:

' l2; hereinafterdesignated as B cathodes,:,alle

ofJthe-cathodes beingmounted in a .,circular;. ar5 rav; with each -A? cathode H interposedptwo; Bi cathodes-IL The main anode ii-h m andlis shown tobe ring-shaped,- and-is support-v1 edin spaced relation withthe =A= and 3B catha odes. An auxiliary, start, reset or normaliz n electrode l4-is.-also provided In one" method of. operating-the stepping tube-,-: the start electrode 1 4' is employed as a start-anode; cooperating with the-electrode Y I 5 which2senves asz a start,- cathode, A a suitable positive potential is the start cathode l 5 .with; conductiorrthen itransferring' so as to exist betweenwthe; maimsanode l3 and:thestartca-thode:I 5? If: anegative Zpul'sm then, be 'appliedl-to the B'fl': catl'mai'es: l2; the-disk.- chargeiwwill; transientinitia'lly'r so v as-ito.- exist be tweentthes'mainianodezand the rst'oneor-tne 13" in Fig. 2. At the cessation of the pulse, the discharge will transfer so as to exist between the main anode and the first one of the A cathodes in a counter-clockwise direction in the structure as shown in Fig. 2. This first A cathode is labeled I! in the structure as shown in Fig. 2 and is supplied with a suitable voltage through an impedance. In a similar manner, successive pulses applied to the E cathodes I2 will cause the conductive path in the tube to transfer so as to exist between the main anode i3 and the successive A cathodes H. The directivity of the stepping is accomplished by the construction of the cathodes, in a manner fully set forth in the above-cited patent application or in any other suitable manner.

As the conductive path progresses step by step from position to position in the tube, the con duotion is limited to one path at a time, i. e., the conduction between the main anode and the previous A cathode II is extinguished. This may be accomplished by utilizing asuitable impedance in series with the main anode of the device whereby the increased voltage drop across this impedance; resulting from the't'ransfer of conduction to a B cathode I2, is sufiicient to cause the voltage between the main anode I3 and an A cathode I I to fall below the sustaining value.

A circuit embodying the principles of the invention is shown in Fig. 3 of the drawing. In this circuit a plurality of multicathode stepping tubes TI to T is provided. These tubes may be of the type shown in Figs. 1 and 2, and in that event, in tube TI, main anode MAI is the correlative of anode I3 in Fig. 2, the first B cathode IBI is shown as cathode IS in Fig. 2, the B cathodes IB2 to IE0 are shown as the cathodes I2 in Fig. 2, the first A cathode IAI is shown as cathode I? in Fig. 2, A cathodes IA2 to I A0 are the correlatives of cathodes II in Fig. 2, the start anode ISA is shown as electrode :4 in Fig. 2, and the start cathode ISO is shown as electrode I5 in Fig. 2. Tubes T2 to T0 are provided with electrodes similarly designated to those of tube TI except for the appropriate change inthe initial character in each designation.

As an exemplary embodiment of the invention, a portion of a mobile radio telephony system has been shown in Fig. 3. At each of the subscribers stations, such as the one represented in Fig. 3, a radio receiver RE and a radio transmitter TR are provided. This apparatus may be of any suitable type well known in the art, and is associated with a telephone handset HS in the nor mal manner. It is assumed that receiver RE is continuously operative to receive all of a relatively large group of subscribers telephonicdesignations, which are transmitted from one or more central point and to apply all of these incoming designations to conductor 30I which is connected to battery through the upper winding of pulsing relay L. The receiver is further assumed to be operable in response to the receipt of any subscribers designation to connect ground to conductor 302, whereby this ground is extended through the No. 3 contact of the switchhook SW to operate off-normal relay ON.

Let it be assumed that a signal has been received by receiver RE and that receiver RE has operated to energize relay ON and to cause current to flow through the upper Winding of relay L to operate relay L so that its armature is contacting the Nos. 3 and 4 contacts thereof. As

the several series of pulses representing the several letters or digits of the called partys designation are applied to conductor 30I through receiver RE, relay L will release at each pulse and reoperate at the termination of each pulse in the normal manner.

Additional windings are shown on relay L for special purposes. The lower winding of relay L is a biasing winding which opposes the upper or operating winding sufiiciently to force relay L to release when the operating winding is deenergized. When relay L operates, the energizing circuit for the lower winding of relay L is completed through resistor 304, No. 3 contacts of relays L and ON and to negative battery. When, subsequently, the upper winding of relay L is deenergized, the current in the lower winding of relay L is such as to assist the start of the release of relay L. The middle winding of pulsing relay L functions as an aiding winding, assisting in both the operation and release of the relay. When relay L is operated capacitor 305 is charged over a path from ground, middle winding of relay L, capacitor 305, through the No. 3 contacts of relays L and ON and to negative bat tery. When relay L is released, the above-traced charging path is interrupted and capacitor 305 discharges through the winding of relay SR to ground. The current flow through the middle winding of relay L, as a result of the discharging of capacitor 305, is in a direction to aid the release of relay L and to insure the closure of the back contacts of that relay. When relay L is again operated, the charging path for capacitor 305 is reestablished'and the current flowing through the middle winding of relay L as a result of the charging of that capacitor aids the operation of relay L there-by insuring a steady front contact closure.

Relay ON is arranged to operate prior to the operation of relay L. This may be accomplished by controlling the time at which the receiver RE grounds the leads 30l and 302 or by the characteristics of the relays per se. Upon the operation of relay ON and prior to the time that relay L hasfirst operated, negative battery is connected through the No. 3 contact of relay ON, No. I contact of unoperated relay L and to ground through resistor 301 and, in parallel therewith, to ground through capacitor 308 and the upper winding of the pulse generator transformer 339. As a result of the surge of charging current for capacitor 308 through the upper winding of transformer 309, transformer 309 transmits a positive pulse through the back contact of unoperated relay SR, conductor 3!!! and to the start anodes ISA to OSA of all the stepping tubes TI to T0. Since the start cathodes ISC to 0S0 are all connected to negative battery, which may supply, for example, a negative 50-volt potential, through individual resistors, each of the tubes TI to T0 will undergo an initial discharge between its start anode and its start cathode/ Since the main anodes MAI to MAO of all of the tubes are connected to positive battery which may supply, for example, a positive -volt potential, through individual resistors, via conductor 3I3, and through the No. 2 contact of relay ON, each of the tubes TI to T0 will immediately undergo a transfer of discharge whereby conduction will exist between the main anode MAI to MAO and the start cathode ISC to 080, respectively, of the tubes TI to T0, respectively. All the tubes TI to T0 are now prepared for stepping.

acreage;

.Upvonzzthe initial.. operatio.n of..relay. L, a .cire

01111531185 completed 1 from. negative. battery; No; 3.. contacts of. relays r ON and L, .Winding of relay SR and to ground whereby relay SR is. operated. Itz will..be noted that. this. operation. of; relaySR cannot; occur. until. relay. L..has closed its No.- 3; contact; whereby ample timewill have: been provided ifor. the transmission; of the. positives puls ;byitransformer 309 through the back :con-.

tact 4.0L relay .SR as l was :hereinbefore. described.

It::may'..:.also be. noted; that. relay: SR. is of the. slosvetosrelease; type .so that it. remains operated despite: the; several momentary interruptions of its; energizing circuitresulting from the pulsing ofrelay: L;

At thefirst release of. relay. Lin responseto the. first. pulse: of the. first: digit of 'the received designation, capacitor 308 will charge overtheabove-traced. path.. A. positive. pulse. is. transmitted 'byetransformer 309 in. response to. the chargin inthesame manner asabove described, butcsince relay- SR. is now, operated, this pulse will r. be. transmitted through the front contact of operated relay. SR, conductor 315, through effective. to createany change in the condition Ofith circuits at. this time. Atthe next operation; of relay L at the end of the first'pulseof: the first digit of the received designation,-

capacitor'308will discharge. through resistor 331- to ground whereby a negative pulse Will be transmitted by. the pulse generator transformer 339'- over. theabove traced path to ground through resistor 3-l6'whereby' a negative pulse will be applied. to all of the B cathodes IBI to IE3 of tube. Tl. Inresponse to this first negative pulse applied to, the B cathodes of tube Tl; the.

conductive-path in that tube will be transferred so. as.t0 exist between the main anode MAI and th'e first B cathode IBI thereof. As a result-,due to the increased voltage drop across anode resistor 31?, the potential at the mainanode MAI of tube TI will drop to a point where the potential difierence between the main anode MAI and the start .cathode- ISC is below the sustaining value, and that discharge path will thereby be'extinguished. As the pulse attenu ates, the discharge in tube Tl will again transfer-so. as to exist between the main anode MA! and thefirst A cathode IAI which is connected 'to negative battery through resistor 3l8. Although the potential drop across the A cathode resistor 3| 8 may be employed as an output signal indicative of'the registration of the digit lfthis has not been done in the preferred embodiment of theinvention inasmuch as the digit 1 is normally not employed as the first digit ofa subscriber's designation.

At the next momentary release andreoperatioI-rof relay Lin-response to the second pulse of T thefirst digit of the received designation, the conductive path in tube T l is successively stepped to the next B cathode IBZ'and then to the next A cathode 1A2, with the prior conductive path between themain anodeMAl and the A cathode IAI being extinguished; The riseainpotential of cathode 1A2 due to the potential drop across resistor 323 appearsatout-- put terminal 32!.

As the; subsequent .firstdigit pulses are. re

ceived; relay L will: continue .to follow the pulses.

alternatively .1 to... charge andr ;discharge.=capacitors 308;: whereby. transformer. 3091 will 2. continue to z transmit negative pulses to the B cathodes= of tubeJIEl; 'Ihe-steppingxof tubeTtcont-inues in. the; aboverdescribed-manner,. with. the conductive'. paththerein xfinallyresting onv that: one of, the .AT. cathodes corresponding .w-ith'thenum ber. of pulses: received... Therefore,- the" output terminaL. associated .Wlth' the-selected -A' oath ode. carries .aupotential considerably positive -rela'- tive to-thepotential which is supplied to the out Put terminals which: are: connected tothe non conducting A cathode.

An .output conductor. 322 is. connected? to 'a SBIECIJBdLOl'lBlOf. the Afcathode output terminals; of. tube. .Tl This connection :is made in accord"---' ance. withthe-firsti'digit oft-he designation of the. particular. subscribers station with-whichthe apparatusisassociated. Thus, assuming the first. digit'rof: the. designation tobe 8 (or;.-acorresponding letter); output conductor -322-*-is connected. to :output: terminal: 323 i which/is connected .tothej eighth A cathode [A8 of tube Tl, asshown'.

At: the termination of the pulses representing-5 any I one digit, relay RA is operated and remains' operated: during the interdigital delay period At any .timethatrelay Lis operated, capac tor 332. ischarging over a path from positive battery; No. 2. contact of relay ON, winding of relay'R-A; resistor. 333;: capacitor 332- and to ground: Asia consequence; a rising p-ositivespotential is applied to the start. anode 33=4of"tube RAI. However; th-etime constant of-that circuitis longer-than? the time betweenhe-pulses representin-g any one digit of a .subscribers designation, and consc quently prior to. thetime'that a discharge is initiated intube RAl, relay-L willmoment-arlly release and capacitor 332 will dischargeand; m fact, charge oppositelythrough resistor 335; No. 2 contact of released relay- L, No. 3 contact of relay ON and to n-egativebattery. At the-end; of the pulses representing any one digit; how--. ever, an inter-digital time will-elapse and "during; this-longer period capacitor 332 will rise-tea sufficient positive potential-to initiatea discharge in tubezRAl betw-een the start "anode 334- andth =cathodei333', which is-c-onnected'to negative'bab tery. Sincethe-main anode of tube RAI isgconnected' to positive battery through the-winding of relay-RA, tube RAI will undergo an immediate transfer of discharge whereby the conductivepath. will exist across: themain gapoftube RAI .and relay EA will be operated.

Relay RA, in operating, connects negativebat tery through its No. 3 contact toconductor 340 which extends to the operating windingsofall of the-register 'and'steering relays DR-l to DB0. The other terminal of each of the operating windings ofthese relays is connected to one'of the tube output conductors; such as conductors. 3'22, 34! or 342. Under this condition, if the initial digit received corresponds to the initial? digit of the designation of the subscribers station with which the subject apparatus is associated, relay DRI will'be operated. Thus, assum ing that the digit "8 has been received, terminal 323 will have risen to a potential positive -relative to the'negative' battery connected to the left-hand terminal of relay DRI and, as a result, relay DRI will be operated. It'willbe seen that had the initial digit been any other=digit than 8, the conductive path in tube Tl would not have included A cathode IA8, terminal 323" would: not havebeenatj an elevated potential.

at the commencement of the interdigital delay period and relay DRI would not have been operated.

Relay DRl locks operated over a path from negative battery, locking winding and No. l contact of relay DRI, conductor 343, and to ground through the No. I contact of relay ON. Relay DRI, in operating opens its No. 3 contact to disconnect the pulse-generator transformer 309 from the B" cathodes of tube TI and closes its No. 2 contact to connect that pulse source to the B cathodes of the next succeeding counting tube T2.

Relay RA, in operating, also completes a circuit from positive battery, No. 2 contact of relay ON, No. I contact of relay RA, resistors 344 and 345 and via conductor 3) to the start anodes ISA to USA of all of the stepping tubes TI to T0. The application of this positive potential to the start anode ISA of tube Tl causes the conductive path in tube TI to transfer so as to exist momentarily between the start anode ISA and the start cathode ISC. The discharge will then transfer so as to exist between the main anode MAI and the start cathode ISC of tube TI. Thus, tube Tl may be restored to its initial condition in this manner if desired. The network comprising resistors 344 and 346 and capacitor 341 provides a time delay to ensure that tube Tl will not be restored to normal before relay DR! has had time to operate and lock operated.

When relay RA operates, negative battery is connected through the No. 3' contact of relay ON, No. 4 cont-act of operated relay L, and through the No. 2 contact of relay RA to the winding of relay RA and to the main anode of tube RAI whereby relay RA is locked operated under the control of relay L and tube RAI is extinguished.

At the first pulse representing the second digit of the received designation, relay L momentarily releases thereby releasing relay RA so that negative battery is no longer connected to the operating windings of the DR-series of relays. At the termination of this pulse, relay L reoperates and transformer 309 transmits a negative pulse through the front contacts of operated relay SR, conductor 315, No. 4 contact of relay DRO, No. 3 contact of relay DR2, No. 2 contact of operated relay DRI and to ground through resistor 349 whereby a negative pulse is applied to the B cathodes 23! to 230 of the second digit counting tube T2. Tube T2 is stepped in a manner similar to the operation of tube TI and, at the next interdigital pause, relay DRZ is operated if, but

only if, the second-received digit corresponds to the second digit of the designation of the subscribers station with which the apparatus is associated, herein assumed to be the digit 5.

The apparatus continues to operate in this fashion, with the succeeding DR-series relays being operated if the successive received digits correspond, respectively, with the successive digits of the subject subscribers designation. As each DR relay except the last operates, it looks operated and transfers the pulse lead to the next succeeding stepping tube.

If the received designation does correspond to the designation of the subscribers station the register and steering relays DR! to DB0 will be successively operated; otherwise, at least relay DRO will remain unoperated. Upon the operation of relay DRt, signifying that the subject subscriber should be signaled, the visual signal comprising lamp VS and the audible signal com- 8 prising bell AS Will both be operated over paths from battery through the contacts of operated relay DRO to ground through the No. I contact of relay ON.

When the called subscriber lifts the handset HS, the No. I switchhook contact will be closed to connect the handset HS to the receiver RE and the No. 3 switchhook contact will be opened to release relay ON. On the other hand, if the incoming pulses do not designate the particular station shown in Fig. 3, relay ON will be released when the receiver RE removes the ground from conductor 302. In either case, relay ON, in releasing, restores the apparatus to normal, extinguishing all of the discharged tubes, releasing the operated relays, and deenergizing the audible and visual signals if they have been energized.

It is to be understood that the above-described arrangements are but illustrative of the application of the principles of the invention. Numerous other arrangements may be devised by those skilled in the art Without departing from the spirit and scope of the invention.

What is claimed is:

1. In a signaling system, a plurality of gaseous conduction devices each having a plurality of distinct conduction positions and each responsive to electrical impulses applied thereto to advance the conductive path therein step by step from position to position, an impulse generator operable to transmit a series of groups of electrical impulses, a chain of relays comprising a relay individual to each of said devices, means in cluding contacts on each of said relays for normally electrically connecting said impulse generator to the first one of said devices, means for operating each of said relays only if the conductive path in the one of said devices to which each of said relays is individual is stepped to a preselected position, each of said relays except the last one of said relays being operable to transfer the connection of said impulse generator to the next succeeding one of said devices, signal means, and means responsive to the operation of the last one of said relays for operating said signal means.

2. In a signaling system, a plurality ofgaseous conduction devices each having an anode, a first plurality of cathodes and a second plurality of cathodes, each of said devices being responsive to pulses applied to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator operable to transmit a series of groups of electrical impulses, means normally electrically connecting said impulse generator to said second plurality of cathodes in said first device, and apparatus including said means connected to a preselected one of said first plurality of cathodes in each of said devices and operative only in response to the advancement of the conductive paths to include the respective preselected ones of said first plurality of cathodes in the successive ones of said devices for successively electrically connecting said impulse generator to the said second plurality of cathodes in the successive ones of said devices.

3. In a signaling system, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes and a second plurality of cathodes, each of said devices being responsive to pulses applied to said second plurality of cathodes,therein., .tc advance theconductive path here hrough. st p. y stepso that said path, ex.- ists between said anode and successiv on s of said first plurality of cathodes, an impulse generatoroperableto transmit a series of groups of electrical impulses, means normally electrically connecting said impulse generator to said second plurality of cathodes in said first device, appae ratus including said means connected to apreselected one of said first plurality of cathodes in each of said devices except the last one of said devices and operative only in response to the ad an emen of in? q duQ l i? Path o. clude the respective preselected .ones of said first plurality of cathodes in the successive ones of said devices for successively electrically connecting said impulse generatorto the said second plurality of cathodes in the successive onesof said devices, .signal means, and means responsive to the advancement of the. conductive path in the last one of said devices .to include the preselected one of thesaid first plurality of cathodes in said last device for operating said signal means.

4. In a signaling system, a plurality of gaseous conduction .devices each having ,an anode, .afirst plurality of cathodes and a second plurality of therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator operable to transmit a series of groups of electrical impulses, means normally electrically connecting said impulse generator to said second plurality of cathodes in said first device, apparatus connected to a preselected one of said first plurality of cathodes in each of said devices for successively electrically connecting said impulse generator to the said second plurality of cathodes in the successive ones of said devices, and means operable at the termination of each of said groups of pulses for operating said apparatus only if the conductive paths in the successive ones of said devices have been advanced to include the respective preselected ones of said first plurality of cathodes in the successive ones of said devices.

5. In a signaling system, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes and a second plurality of cathodes, each of said devices being responsive to pulses applied to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator operable to transmit a series of groups of electrical impulses, means normally electrically connecting said impulse generator to said second plurality of cathodes in said first device, apparatus connected to a preselected one of said first plurality of cathodes in each of said devices for successively electrically connecting said impulse generator to the said second plurality of cathodes in the successive ones of said devices, means operable at the termination of each of said groups of pulses for operating said apparatus only if the conductive paths in the successive ones of said devices have been advanced to include the respective preselected ones of said first plurality of cathodes in the successive ones of said devices, signal means, and means responsive only to the advancement of the conductive path in the last one of said devices to include the preselected one of the said first plurality of cathodes in said last.- device. for. operating said signal means. I

6. In a signaling system, a plurality of. gaseous conduction devices 'each having an anode, a first plurality of cathodes and a second plurality of cathodes, each of said devices beingrespons'ive to pulses appliedto said second plurality of cathodes therein to advance the conductive path therethrough step .by step so that said path exists .between said anode andsuccessiveones of said first plurality of cathodes, an imp'ulsegenerator operable to transmit a series of groups of electrical impulses, and a chain of relayscomprising a relay connected .to apreselected o'neiof the said-first plurality of cathodes .in each of 'saiddevic'es and operative only .inrespons'e' to the'advancem'ent 'of the conductive path to include the said preselected cathode in'lthe associated one of said devices .forielectrically connecting said impulse generator to the next succeeding one of" said devices. 1

7. Ina signaling system, aplurality of gaseous conduction .devicesieach having .an anode, afirst plurality of cathodes and asecond plurality .01 cathodes, each of said, devices lbeinglresponsive. to pulses appliedto,saidsecondplurality. ofcathodes therein to advance the conductive .path there through stepbystepso that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator operable to transmit a series of groups of electrical impulses, and a chain of relays normally electrically connecting said impulse generator to said second plurality of cathodes in said first device and comprising a relay connected to a preselected one of the said first plurality of cathodes in each of said devices and operative only in response to the advancement of the conductive path to include the said preselected cathode in the associated one of said devices for electrically connecting said impulse generator to the next succeeding one of said devices.

8. In a signaling system, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes and a second plurality of cathodes, each of said devices being responsive to pulses applied to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator operable to transmit a series of groups of electrical impulses, a chain of relays normally electrically connecting said impulse generator to said second plurality of cathodes in said first device and comprising a relay connected to a preselected one of the said first plurality of cathodes in each of said devices and operative only in response to the advancement of the conductive path to include the said preselected cathode in the associated one of said devices for electrically connecting said impulse generator to the next succeeding one of said devices, and signal means operative in response to the operation of the one of said relays associated with the last one of said devices.

9. In a signaling system, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes and a second plurality of cathodes, each of said devices being responsive to pulses applied to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator operable to transmit a series of groups of electrical impulses, a chain of relays normally electrically connecting said impulse generator to said second plurality of cathodes in said first device and comprising a relay connected to a preselected one of the said first plurality of cathodes in each of said devices, and apparatus operable at the termination of each of said groups of pulses for successively operating said relays only if the conductive paths in the successive ones of said devices have been advanced to include the preselected ones of said first plurality of cathodes in the successive ones of said devices.

10. In a signaling system, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes and a second plurality of cathodes, each of said devices being responsive to pulses applied to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator operable to transmit a series of groups of electrical impulses, a chain of relays normally electrically connecting said impulse generator to said second plurality of cathodes in said first device and comprising a relay connected to a preselected one of the said first plurality of cathodes in each of said devices, apparatus operable at the termination of each of said groups of pulses for successively operating said relays only if the conductive paths in the successive ones of said devices have been advanced to include the preselected ones of said first plurality of cathodes in the successive ones of said devices, and signal means operative in response to the operation of the one of said relays associated with the last one of said devices.

EDWARD VROOM.

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

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