US2481919A - Multiway regenerative repeater system - Google Patents

Description

Sept. u, 1949.

K. E. FITCH MULTIWAY REGENERATIVE REPEATER SYSTEM 3 Sheets-Sheet l Filed Aug. 25, 1945 ATTORNEY Sept. 139 1949. K. E. FITCH 2,481,919

MULTIWAY REGENERATIVE REPATER SYSTEM Filed A ug. 25, 1945 5 Sheets-Sheet 2 REGENERAr/vs @EPL-'ATER 4 /03 l l y /09 POLARZED DOUBLE SPACE HY PASS IIN/' /NVENTOR K E F/ TCH By JM f. CM-yn ATTORNEY Sept- 13, 1949 K. E. FrrcH MULTIWAY RIEGEERA'IIVE REPETER SYSTEM 3 Sheets-Sheet 3 Filed Aug. 25, 1945 lll l l l patented Sept. 13, 1.949

MULTIWAY REGENERATIVE' REPEATER SYSTEM Karl E. Fitch, Summit, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application August 25, 1945, Serial No. .612,679

12 Claims.

This invention relates to telegraph repeaters and more particularly to an improved multiway regenerative telegraph repeater.

An object of the invention is the improvement of telegraph repeaters.

A more particular object of the invention is the improvement of multiway regenerative repeaters.

By a multiway regenerative telegraph repeater is meant an arrangement wherein more than two telegraph lines or loops, each equipped with an individual telegraph repeater, are interconnected through a hub into a half-duplex concentration group served by a single regenerative repeater unit in such a manner that any one of the individual telegraph lines or loops can transmit through the single regenerative unit to all of the other interconnected lines or loops simultaneously. As is well known in the art when telegraph signals are transmitted over long lines, which may include telegraph repeaters of the nonregenerative type, they tend to become distorted. It is therefore necessary at times, before further transmission is feasible, to transmit the signals through a regenerative repeater which is designed to receive the distorted signal elements and in response thereto regenerate and retransmit signal elements which correspond exactly with the original signal element in shape and duration. IThe regenerative repeater identities l the nature of each signal element, generally by sensing the middle portion of the signal element, and then transmits a signal element of corresponding nature and of standard length by means of a mechanically or electrically controlled tim- .ing device which restores each signal element to its standard duration. It is particularly pointed out that only a single regenerative repeater unit is required to serve any concentravtion group of interconnected lines or loops in a multiway regenerative repeater at a particular city. Numbers of such groups located in diierent cities remote from each other are ordinarily interconnected together through an individual regenerative repeater for each group. Although presently known multiway regenerative repeaters operate generally satisfactorily, it has been found that they are subject to a diliiculty which results in the occasional loss of a short message when two or more parties at remote points seize the line approximately simultaneously. The reason for this is that spacing signals cannot pass each other over the system.

lt is a more specific object of this invention 2 to prevent the loss of short messages on multigroup networks interconnected through multiway repeaters.

The loss of short messages on multigroup networks is prevented through the modication of the presently known multiway repeater circuits to provide what will be termed hereinafter a double-space lay-pass feature. The double-space lay-pass feature permits space signals in effect to pass each other at regenerative points and minimizes simultaneous sending by assuring rapid and positive mutilation of local copy which serves as an indication of the attempted simultaneous transmission.

A feature of the invention is a double-space by-pass arrangement incorporated into a multiway regenerative repeater.

A further feature of the invention is an arrangement whereby the multiway regenerative repeater and the double-space by-pass circuit may beA readily interconnected or disconnected as required bythe repeater attendant depending on the needs of particular networks as they are established or modied thus eiecting a saving in the number of double-space by-pass units required.

A further feature of the invention is the modication of the directional repeater so that it can respond to a spacing or break signal received from a connected line repeater during the interval while a spacing signal is being transmitted from the directional repeater toward the line repeater.

A further feature of the invention is the provision of an arrangement in the directional repeat'er' so that it can discriminate between a spacing or break signal received from a line repeater and a spacing or break signal received from a subscriber loop during the interval while the directional repeater is transmitting a spacing signal toward the line repeater or the subscriber loop and which enables the directional repeater to respond to the spacing or break signal received from the line repeater and remain unresponsive to the spacing or break signal received from the subscriber loop under such conditions.

These and other features of the invention may be understood from reference to the associated drawing, disclosing a preferred embodiment of the invention, in which:

Fig. 1 shows three directional repeaters connected individually to three telegraph channels;

Fig. 2 Shows a regenerative repeater, a doublespace by-#pass unit and a hub through which the directional repeaters of Fig. 1 are interconnected There has heretofore been a diiiculty encounto Fig. 2; and teled in the operation of multiway regenerative Fig. 3 shows a typical half-duplex mulitway repeater networks in that it was impossible for regenerative repeater network formed by intera spacing signal generated in one concentration connecting subscriber loops and telegraph lines 5 group at a particular city to pass another spacing through three Figs. 1 and 2 in three diierent. signal generated in a concentration group at an- Cities other city. `.Under-such circumstances short messages were 'frequently lost. lThe double-space by- GENERAL DESCRIPTION OF THE SYSTFM pass unit shown at the lower part of Fig. 2 now Refer t Figsl and 2- Before pfoceedmg Wlt'h l0 prevents this from happening. By means of the a detailed description, a general description of the doublepace .by pas unit, if for instance direc- Operation `O the System Will be 'given- F1g5 '-1 tional repeater No. 1 is transmitting a spacing and 2 when interconnected with Fig. 1 at the Signal and Simultaneously a spacing signal is left of Fig. 2 exemplify the circuits constituting a -receved from direc-tional repeater No. 2 the particular concentration group together with Vits doub1e spa gbygpass unit Wm identify the Conc-[1 regenerative repeater and tS doube'spac? by* tion. The vdouble-space by-pass unit will prolong DESS unit in a telegraphtest I@02H11 at arpar'tllllar the `spacing interval for a measured period whencity. Other corresponding circuits Such as Flg- 1 ever two spacing signals are received simultaneand Fie. 2 will be located et distant cities and ously or in suoli e time relation that their interinterconnected into a ne'tWOrk by e Single Pel?- 20 vals overlap- When such a condition occurs the graph channelinterconnectingthe groups as 1nd1- doub1e space b5/:pass inuit willv impress a prt)- cated in Fig. 3. Extending from the lefthand longed spacing signal onthe entire system. The margin 0f Fig. 1 are three conductors. Each 0f spacing interval will .be .prolonged sufciently so these three 'conductors may connect externally tiiatit has time 4to reach tnefmos't remote Lfacility t0 a telegraph line repeater, not Shown, 'and 25 connected into the system. As long as simultanethrough the repeater to a telegraph-channel eX- ous transmission continues, long spacing .signals tending t0 e dstttrlt rCiti 01' the Conductor may will be .generated and impressedon the system 'by' connect to a local subscriber telegraph loop or a the doub1e space by pass unit The eect of this particular conductor may 'connect t0 'beth a 1in? is to mutilat'e thersignal'e which .are transmitted repeater and a loop. Each telegraph Channel 1S 3o and lto 'insure that they are received by ever-y interconnected through -an individual directional facility Connect-ed into img system. The message repeater marked directional repeater N0 -1I `2 and which isreceivedfat each station will definitely be 3. in Fie. 1 t0 'c hub circuit Shown et the left 0f mutilated and will continue to -be 'mutilated es Fig. 2. The three directional repeaters-are served long tas .simultaneous transmission Continues, bye. single vregenerative `repeater unit chown at a5 This serves as an Vindication that `more than one the tOlJ A0f Fg- A2 and by e double-Space hr-Dass transmitter is :being operated 'simultaneously on unit shown at the bottom yof Fig. 2. Although the system. 'Onfobservi'ng-the condition, the parthere are but three directional repeaters shown-in ties :who 'are :transmitting:simultaneously will stop Fig. v1, it is understood that rany num-ber 0f re* and'transinitting.mayibe'resumed by'one party.

peeters up to 'ten may be interconnected in a 40 on its regenerative 'side each directional rehv particular Concentration group. If vmore than ten peater is 'wired 'to 4'iii/e individual hub circuits,l

arerto vbe interconnected, two hub groups are shown'atithe fleft of-Figj2. The regenerator and interconnected. Signals may be received from the double-space thy-pass Aunit are connected to cerfacility connected to directional repeater No. 1 tain of these hubs through a special jack circuit over its corresponding'telegraph-'channelend imf45 shown alsoat the left 'of Fig. 2. The jack circuit pressed 0n the regenerative repeater. The regenprovides 4for 'substitutions of regenerators and erative repeater 'will reshape and Tetme 'the Sigdouble-space Aby-pa'ss 'units by patching.

nal and transmit the signal simultaneously to p Y directional repeater No. 2 and directional repeater DETAILEDDESCRIPTION OF OPERATION 0F SYSTEM No'. 3 and through them over -the telegraph chan- 60 R 'e'at'er n' e't nels individual -to each vto remote cities where the ep a d n work when idle channels Vare extended through :individual "direc- Each-of fthe relays .shown Ain Figs. 1 and 2 extional repeaters to the hubs of other concentracept power supply relay 92 in Fig. 2 is a high tion groups vor to the connected subscriber VVVloop. speed ipolar relay, The `circuitper Figs. 1 and 2 Thus, any one of the -telegraphriacilities:connected is "shown for the :idle condition which'is the .Same to directional repeater '1, 2 or 3, "or'others if there as for the marking condition. The various relays are more in the group, may transmit through the in Fig. 1 and Fig. i2 will bein vthe .condition shown single one-way regenerative-repeaterunit tovall of for reasons which will become apparent hereinthe other channels interconnectedto a particular after. When the network :is idle receiving break group at a particular city, as well as to all of the "'60 relay YI and receiving relay 2 'associated with other groups at the remote cities and through the directional rep-eater No. l are in the marking conregenerative repeaters at the remote cities to each dition as shown. The :corresponding relays in of the facilities connected Ainto the various groups directional vrepeater viNo. 2, :relays 20! and 22,

at'the remote cities. Y Y and rthe corresponding relays in directional rei -Signals incoming to a'particular directional re- '65 peater No. 3, relays 30| :and 302, are also in the -peater connected to a 'particular channel vof -a marking condition. The directional repeaters group ata particular city vare impressed on kthe transmit polar Vsignals. toward the distant end incoming circuit of Vthe single regenerative refrombatteries whichs'may, for instance. be i130 peater unit'associated with the group and, after volts. The-directional repeaters transmit neutral regeneration, are impressed simultaneously by '70 signals through a .hub circuit toward the regen-` theoutgoing circuit of the single regenerative erator repeater. The signals may, for instance, repeater unit on all of the other directional rebe negative 48 volts for marking and ground for lpeaters connected into the group except the spacing. The regenerative repeater terminates directional repeater from which'the 'signal was on its incomngvside iin Ynegative 'L18-volt battery received. and on its 'sending side 'connects vnegative" 48 volts to the sending hub for marking and ground for spacing.

It will be assumed that the incoming signals were last received by directional repeater No. 1 from the incoming channel. Under this circumstance holding relay 3 will be in the spacing condition. Holding relays 203 and 303 in directional repeaters Nos. 2 and 3 will be in the marking condition. The sending relays Nos. 4, 204 and 304 in directional repeaters Nos. 1, 2 and 3 will be in the marking condition. The reasonsvior this will be made apparent below. The detailed operation of the regenerative repeated in the upper portion of Fig. 2 is described in detail in Patent 2,105,173, Walter J. Zenner et al., January 11, 1938, and Patent 2,337,496, W. T. Rea, December 21, 1943. The descriptions of these patents are incorporated herein by reference as though fully set forth herein. Receiving relay 8| in the regenerative repeater will be in the marking condition. The transmitting element I0| of the regenerator unit will be in such position that contact |04 is closed.

Plug |32 will be withdrawn as indicated from jack 3|. Under this condition a circuit may be traced from battery through the winding of relay 92, contact 13, contact 10 and contact |33 to ground energizing relay 92. The armatures of relay 92 will be actuated to close contacts 94 and 95. With contacts 94 and 95 closed, power is supplied from power source 93 to motor 90 so that the driving shaft associated with the regenerative repeater mechanism is turning continuously. A stop arm, not shown, engages a shoulder on cam 99 and prevents the driven shaft of the regenerator from rotating through friction clutch 91. The filament of vacuum tube |23 is heated over a circuit which may be traced from ground through battery I i6, resistance II'I, resistance I 24, lament of tube |23 and resistance |22 to ground. Condenser |20 is charged to the potential of battery I I6 over a circuit from ground through positive battery IIB, resistance IIl, resistance IIS and Variable resistance IIB to the left-hand terminal of condenserY |20, the right-hand terminal of which is connected through resistance I2| to.ground. The grid of tube |23 is connected through resistance |40 to the junction between the left-hand terminal of condenser |20, left-hand terminal of variable resistance |I8 and spacing contact II5 of relay ||3 which at this time is open. Current normally flows through vacuum tube |23 over a circuit which may be traced from ground through resistance |22, filament of tube |23, plate of tube f |23, winding of relay |25 and resistance |I`I to grounded positive battery. For this condition the armature of relay |25 is actuated to the left to engage its contact |26.

With the various relays in the assumed condition, a circuit may be traced from positive battery I3. through resistance I4, marking contact II of transmitting relay 4, through inductance coil Sii and resistance 3| in parallel to the apex of relay 2 where parallel branches are formed. One branch extends through the top winding of relay 2, top winding of relay I, resistance 2| and variable resistance I9, which connects either to 'a line repeater and through the line repeater to a multiway regenerative repeater concentration group, such as that per Figs. 1 and 2 at a distant city as indicated in Fig. 3, or the variable resistance I9 may be connected to a subscriber loop circuit. In either case the connecting circuit iS terminated in negative and positive battery of the same magnitude as batteries I3 and I5. Neg- ,ative battery will be connected at the distant end tom winding of-relay I is shunted by resistance 24; From the right-handterminal of resistance I a branch extends'through resistance |44, and resistance |42 which is shunted by condenser |43 to the top terminal of resistance 23. These resistances and their connected battery constitute a potentiometer network which controls the magnitude of the currents owing in the bottom winding of relays I and 2 which varies one from the other for different conditions to be explained hereinafter. The effect of the current owing in the top winding of relays I and 2 for this condition tends to operate the armatures of relays I and 2 toward the left to engage with their respective marking contacts 5 and 1, while the effect of the current flowing in the bottom windings of relays I and 2 tends to actuate the armatures of these relays toward their respective right- hand contacts 6 and 8. For the marking condition the eifect of the current iiowing through the upper windings of relays and 2 is dominant over the effect of the current flowing in the bottom windings of relays I and 2 and the armatures of relays I and 2 are maintained in engagement with their respective marking contacts 5 and 1.

Since contact 8 is open and ground from the armature of relay 26 is therefore not connected vto contact 8 and since the same condition prevails at contacts 208 and 308 there is no ground connected through conductors d5, 5i) or 55 to receiving hub 62. From hub 62 a circuit may be traced through contact E5, contact 98, top winding of relay 8|, resistance 8l, resistance 85, which is shunted by condenser 8E, and negative battery 84 to ground. For this condition therefore the top winding of relay 8| is not energized. A circuit may be traced from grounded negative battery 84, through resistance 88 and the bottom winding of relay 8| to ground. The effect of current flowing in its bottom winding maintains the armature of relay 8| in engagement with its marking contact 82. For this condition a circuit may be traced from grounded battery 89, through resistance 90, armature and contact 82 of relay 8| and the winding of the regenerative receiving magnet 9| to ground, energizing magnet 9 I. When the magnet 9| is energized while awaiting the reception of a train of signal elements, the driven shaft of the lregenerative repeater mechanism is prevented from rotating in the manner explained in the foregoing. Sending contact |04 of the regenerative repeater is closed for this condition and a circuit rnay be traced from grounded negative battery |05, through resistance |05 which is shunted by condenser |08, resistance |01, contact |04, conductor |09, contact B'I, contact 64 to sending hub 6I, where parallel branches are formed. In the case of directional repeater No. 1, branch 42 extends through the top winding of relay 4, resistance 4I and resistance 39 shunted by condenser 40 to contact I0 of relay 3, which is open since as explained heretofore, the armature of relay 3 is in engagement with its spacing contact 9. VIn the case of directional repeater No. 2 the parallel neonato.

flinch-extends. through conductor 41, 'top Lvrinding of relay 204, resistance 24|., .resistance l238, 'wl'xich-is-shunted by condenser 240, contact 2&0, whichris closed, .and the armature of relay 2.03110 negative battery 229-. In the case of' directional repeater No. 3 the parallel branch extends through yconductor-152, top winding of relay 304, resi-stance 34|, resistance 339, which is shunted by condenser V340,1eontact 310, which ciosed, and the armature of relay 303 to negative batteryl 329. .No-current therefore flows in the top windings of any ofthe sending relays in directional repeaters No. 1, 2 or 3. "The armatures of each of theserelays is maintained `in engagement with its respective marking contact due to the eifect of current owing vthrough its bottom `winding in each instance. In thecase of relay 4 the circuit may be traced `from ground through resistance 38 to parallel branches. One branch extends through resistance 31 and negative battery 36 to ground. Theother branch extends through the bottom kwinding of relay 4, resistance li8 and negative battery l1' to ground. The-corresponding circuit for relay 204 maybe traced-from ground through resistance 238 to par- 'a'llel'branches One branch extends through resistance `2311 to negative battery 236. The other branch extends through the bottom winding of relay V'2M andresistance 218 to negative battery 21T. In the case of relay 304 the circuit extends from ground through resistance 338 to parallel branches. One branch extends through resistance 33T `to negative vbattery 335. The other lextends through the bottom winding of rea-y 304, resistance 3 i8 and negative battery 3 I1 to ground. A circuit may be traced from negative battery 29` through the armature spacing contact 9 and bottom Winding of relay 3, resistance 32, which is shunted by condenser 33, and conductor 44 Ato 'holdinghub 58 which 4extends through the holding hub resistance 51 to ground.` The `current ,flowing through the bottom winding .of relay 3 may, .for instance, Ybe .025 ampere vfor this condition and its effect is tending to actuate the armature of relay 3 towards its spacing contact 9. `With the armature of relay 2in engagement with contact 1 this effect is opposed by the'euect lof current in the upper Winding of relay 3 which is tending to actuate the armature of relay 3 towards its marking contact l0. The magnitude of the current in the upper Winding may, Vfor instance, be .020 ampere and the armature of relay 3 will be maintained, as has vbeen mentioned, .in engagement with Vits spacing contact No.` 9. The circuit which controls the flow of current through the upper winding of relay 3 is in the form of a double potentiometer. 'The circuit may be vtraced from negative battery 29 to the junction between resistances 26 Vand 28.` From this junction one branch of the circuit extends through resistance 28 to the junction of second parallel branches. One second branch vextends through resistance 21 to ground. rIrhe other second branch extends through the top winding of relay 3 to the lower .terminal of resistance 26, from which point the circuit extends to marking contact 1 of receiving relay 2. When the armature of receiving relay 2 is. in engagement with lits marking contact .1 the .circuit 'is extended through the armature of relay 2 to ground. The magnitudes of the resistances and of the battery forming the Vpotentiome- .ter have been so chosen that the direction of the idow ci current through the top winding of relay 3is reversed as the armature of relay y2 engages with---and diseneases from contact 1. .re-

verset is almost instantaneous because it is effected simply by the engagement and separation of thearmature of relay 2- Withand from contact 1. In. .thecese of relays 2ll3l and 303, since their respective 'armatures are not in engagement with their respective spacing contacts 229' and 303, no `current is owngthrough the bottom windings of .these relays. The potentiometer circuit con.- nectedto thetop windings of relays 203 and 303 is identical vin its arrangement with that connected to. the v'top winding of relay 3. The effect of the :current owingthrough the top windings `of re- -lays 203and3l3 is in each instance in a direction to maintain the armatures of these relays in engagement vwith theirrespective marking contacts 210 and 3|'0.

'Transmission toward the reycnerator It. will now -be assumed that the lineV associated with :directional Vrepeater No. 2 starts to send toward the regenerator. It will be assumed that thesignals which are received are. the well-known trains of start-stop permutation code signals comprising a. start elementv which is always a spacing signal -element, five. permutation code ycharacter forming elements which may be marking or Vspacing signal elements -i-n any combination depending upon the particular character and a stop element which is always a marking signal element.

The first signa-l element which .is received is a spacing signal element and will interrupt the flow .of current in .the upper windings of relays 2.0i and 202 and thereby vcause these relays to operate to .their respectiveA spacing contacts 206 and .203 under the influence loi current in their lower windings. Closure of contactZB connects ground through conductor v5l]v to receiving hub S2 from which point -the circuit has. been traced through the top winding of relay 8l. As a result of. this, the. armature 4vo relay 3l will be actuated to engage its. open A.spacing Contact 83.. This in turn will -deenergize regenerator receive magnet 9| which will remove the stop arm (not shown) from engagement with a. raised surface on the periphery of cam 99 and permit cams 98 and 99 to rotate through-one complete revolution during which interval, in .addition to the start pulse, the five character orlning .elementsand the stop sig- .nal .element of. which each signal train is confstitutedwill be received in sequence from directional repeater 2. The armatures of relays 29.! and 202 `operate in unison while relay 204 remains in the. marking condition. The instant that the yarmature of relay 202 breaks from its marking 4contact 2&1 and before the armature .of relay 202 Ahas .completed its travel to engage .itsfspacing contact 208, the. direction of the How of current in the top winding of relay 263 will m rbe reversed and the armature of relay 2&3. will l'l5 holding hub resistance 5l.

be .actuated to. engage with its spacing contact 20.05. When the armature of relay 263 engages withits spacing .2&3 a circuit may be traced from negative battery 2.2.9, through the armature spacing contact 20S and bottom winding of relay 203, lresistance v232 Vwhich 'is .shunted by condenser 23.3,', conductor 4.9., holding hub 58 and through hub resistance '5T to ground. Since the armature of relay '3 is stili 'in engagement with its spacing ,contact 3, since it is assumed that the external 4channel cormected to directional repeater l was thelastto transmit toward the regenerator, there .are twoifparallel branches, namely, the branches connected to conductors 44 and 49, connected to The .magnitude lof thecurrent owing; in the bottom winding 4of relay 3 and inthe `bottom Winding of relay 203 may be, for instance, approximately .015 ampere for this'- condition.. `lrThis current will be insuil'- cient to maintain the armature of relay 3 in engagement 'with its spacing Contact for this condition since, Aas Yexplained in the foregoing, it is opposed by a current of approximately .020' am.- pere in the, top winding-of relay 3 which is tending to actuatethe armature of relay 3 toward its marking contact II0.'-""The armature of relay 3 Willtherefore be actuated to close its marking contact l0.. the case` of relay 203 the effect o f Ithe- 'current in .both its top and bottom windings at this timefis tending to lmaintain the armature frel'ay 203m engagement with its spacing-'contact andfthefarrnature of relay 203 will remain" in engagement with its' spacing contact. Thelinstan't rthat theV armature of relay 3- disengages -rOmits spacingcontaict3- one of the parallel branches Vcornected'to vholding hubl resistance 5'l,=.narnely,'. the --branch4 through conductor 44 .in directional repeater No.V 1, will be disconnected and the current through the bottom vlinding of relay .203 will'risf. to its full value of .025 ampere in a spacingfdirection and this will be sufcient tohold the armature of relay 203 in engagementhwith its spacing contact 239 after the -cu'rrent'in -its upper winding has been reversed to .020 ampere in a marking direction by reception of marking pulsesv from the line repeater associated with repeater No. 2 during communicationandthe consequent closing .of contact T.

l .'From the foregoing 4will be .apparentA that only one of. the holding relays, 3, 203, or 303 in the various `directional repeaters can be locked in the spacing condition by current ilow through its bottom winding to the holding hub resistance 57 at any one time.

, It is veryimpor'tant that a holding relay such as 3, 2.03 or'1333, which has been previously locked tofits spacing Contact .while it has been receiving communicationlfrom its external channel or during the.l waiting interval thereafter, be very quickly released, when a second channel starts to transmit and the corresponding holding relay in the second channi is operated to its spacing contact by c urrent in its upper winding, in order tov arrange the. circuit ofthe holding relay which has been. formerly locked to spacing so that the directional repeater with which itis associated is in a conditiomto transmit, before the rst regenerated signalelement from' the newly transmitting channel is -receivedjr'om the regenerative repeaten Mention .waslinade of the double potentiometer arrangement .connectedto the top windinglof each of the holding relays 3, 203 and 303andf-of the fact that. ,current through the top,.,ivinding of .these relays was reversed instantly 'upon the .engagementor disengagement of the corresponding receiving relay 2, 202, or 302 rfithor from its respective marking contact fl, gill 'or ,301. It is vthe function of .the condenser such as ".33,7233 or 333, shunting resistance 32, 232 or.. 2,32 l"to speed up the release of a relay which has beenlockedin the spacing condition. ".ll'iev effect of the connectionof the condenser in each of these circuits 1ls-to produce an instantaneous surge of cur'rentin the marking direction or a magnitude suiiicient to release the 'held relay, such as relay. 3 in the directional repeater which last transmitted toward the` regenerator.

-It has been; assumed thatV the directional repeater N0.- 1 'was the lastftefrsceive fromts external channel and that the armature ofits relay 3 is in the spacing condition when a signal is rst received by directional repeater 2. If the start pulse had been received from thel circuit associated with directional repeater No. 3, relay 3 of directional repeater No. l would have been operated to marking when relay 303 of directional repeater 3 Was operated toward spacing in the manner described for directional repeater No. 2. The start pulse in this case would have been transmitted over conductor 55 and into the regenerative repeater through hub 62. If the start pulse had been received from the line repeater associated with directional repeater No. 1 the holding relay 3 of directional repeater 1 would have remained in the spacing condition and re' ceiving relay 2 would have transmitted the start pulse through hub 62 to the regenerative repeater. The holding relay such as 3, 203 or 303 in anydie rectional repeater is therefore operated to spacing only when its directional repeater starts tosend toward the regenerator and the holding relay remains locked in the spacing position as long as transmission continues to be received from the line associated'with this particular regenerative repeater. and, after transmission in this particular direction ceases, the armature of the holding relay will remain in the spacing condition until it is released by the operation of a holding relay in another directional repeater which startsY to send toward the regenerator.

The directional repeater which is sending to ward the regenerator will continue to transmit through hub 62 on an inverse neutral basisconnecting ground to the hub through its respective receiving relay for spacing and removing ground from the hub for the marking condition. fl

Reception from the regenerator The initial start pulse transmitted toward the regenerator by the receiving relay 202 of directional repeater No. 2 as described in the foregoing will be regenerated and after a momentary delay will be repeated by the regenerator to sending hub 6I. The regenerator grounds sending hub 6| in repeating the start pulses by positioning the right-hand end of transmitting lever llll in its lower position in response to the deenergization of magnet 9|, which closes contact |03- connecting ground through contacts 6'! and 54 to hub 5I. Current ilows from ground on hub 6| through the top windings of all transmitting relays such as 4 and 304 to negative 48-volt battery such as 29 and 329 except through transmitting relay 204 associated with directional repeater No. 2 which is transmitting toward the regenerator. Current is prevented from flowing through the top winding of relay 204 because the associated holding relay 203 is in the spacing condition and there is no closed path therefore through the top winding. of relay 204, contact 2|() and the armature of holding relay 203 to negative LlS-volt battery 229. Transmitting relay 204 of directional repeater No. 2 thus remains in the marking condition under the influence of current in its lower winding. The transmitting relays of all other directional repeaters are operated to the spacing condition by the eiiect of current in their upper windings because the path through the armature of each of the holding relays such as 3 and 303 is closed through to negative battery such as 29 and 329 in each instance. The start pulse will therefore be repeated to all line and loop facilities which are associated with directional repeaters other than directional repeater No. 2 which is sending associated linesind l tei-posing the stop` arm in the path 'of a raised i surface of cam 99. Then the cycle will be repeated for the next character.

When the direction of transmission changes the holding relay of directional repeater No. `Zvvl'iitli has been transmitting toward the regenerator 'is operated to the marking condition and the holdingirelay of the directional repeater which is beginning to transmit toward the regenerator is locked in the spacingcond-ition before the start pulse is retransmittedby the regenerator;

Break:r feature First the manner in which `the multiway regenerative repeater functions-for the transmission of 'a vbreak sign-aivvhen the double-space bv-riass circuit is disconnected will 'be described. Let it be assumed that contacts 16 and 'I1 are opened disconnecting the double-space lav-pass circuit.

A. While directional repeater-No. 2 is' transmitting toward the regenerator let it beassumed that 'the line associated with directional repeater No. 1 trlesrto break by sending va spacing pulse of several kseconds duration by connecting positive battery to the channel incomingl to `directional repeater No. 1. If the spacing pulse is received when the transmitting relay A4 of directional repeater No. l is in the spacing condition receiving relay 2 of directional repeater 1 will remainin the yrnarl'ring condition because the magnitude of the holding current in the lower winding of relay 2 exceeds the vmagnitude of the spacing current in the upper winding of relay '2. It. is important to observe that with this arrangement, that is with the double-space by-pass circuit disconnected, a break signal is not effective while a spacing signal is being transmitted against it `As soon as the transmitting `relay 4 operates to marking, however, in response to the next marking signal element from theA regenerator, thecurrent in the lower winding of relay 2 reverses to the spacing direction and since there is now no current in the upper winding of relay 2f, relay 2 operates to the spacing condition iollowed by its associated holding relay 3.' Operation of holding relay 3,to the spacing condition will serve to prevent reoperation of transmitting relay 4 to the spacing condition and thus insure passage of the break signal byreinoval ofv-negativeiB-volt battery from the operating circuit of relay 4 at open contact I0. This will also cause the holding relay 203 of directional repeater No. 2 to operate to its marking condition in the manner described in the foregoing. Operation of receiving relay 2 of directional repeater No. 1 to the spacing condition connects ground through conductor 45 to receiving hub 62 and transmits the break signal to the regenerator.

After a momentary delay the break signal is repeated by the regenerator which connects ground to sending -hub 6|- and causes the transmitting relays 204 `and 304 of directional repeaters Nos. 2 and 3, respectively, toY operate to the spacing condition and repeat the break signal to their nais from theirfsocated'iiwminmltamonsly the directional -nepeeterfwhiclrfto receive. a spacing'signar,aft'erV repeater has. changed back to maxtingfwill gn control of the lhoitlngfrelay will bein thespaeingccndition.

` .DOUBLE-Srsclzfrfrssffmm As mentionedfabove-the' ivy-pass circuit is shownl at the/lowetrightof Fig. 2. It ,is connected to double-spaceireceiving 5l fand doubie-space'scndng hub IQ hymns oijl'mb. jack 'l5 and by-passjack Hfwhieirperniit-substitution of one-double-space-by-pass fcr'another by patching.` The by-passjcircuit provides a form of break feature since itspurpose is to notify an interconnected "teierype'writer numana particularlya sending teltymrter lstation that more than oneteletypewrterstationon the samt half-duplex Vnetwork is sending simultaneously.

The lay-pass -crcitneednot ,aiways be provided andwithout. it the multiwayregenerative repeater network is1 capa-ble x offbresking i1-Liliev normal manner described in :the oregoingc'ne' by-pass circuit is' particularly whmziznumber of ,multiwayv regenerative n:repeater arrangementsr are included -i-n alarg'emultlsiation teletiming circuit which protratta-ihn Spacing, signal vtfor an extended interva when twoy are received substantially simulta neously to insure propagation to themost rcmote stationpcnnccted v'to the mostremote group inthe-,netwerk Y'urther it makes it possible tofreceivnf-afspacefthmugh a directional repeater which, .at the 'is transmitting a space received*from'tnegegenerator. Thus no signals vcan be, lostf The 'eifectfof the operation of the'douple-space'bspm circuit isv to continue to transmityicng spacing signals while simultaneous transmission which..v mutilates the signals received Vbygall.stations lnterconnccted'-ithrcrlfxgh the network as'anebctveindication' Ufhd COIldiiOn.

Y Duringnormaimmmisien-mzaeireaimai repeater to the regenerator-thereceivingv breakr` relay in the particular directions? repeater which is transmitting towardthe regmeratbr such-*asl receiving 'breakl relayV if inV directionai repeater' No. i respondsfto thc'signals incoming'fromthe line repeater crSubScribcrsiGOni'JEach-timethe .receiving break relay sncliasfrciay ieperatesA to,

yspacing it connects erigir time ,sani

as grounded high resistance l!" a' ccn doctor such as conductor 4l 1to1 tireffddubie-spml'e by-pass receiving hub 59'.' Prom; hiib like circuit extends throughcontact i-fof lia'nd contact Bil of jack 18, top winding of rciaysiitand :i i!

'in series and resistanceiila tornositiyebatterly HS. This causesy spacingcurrent Avv'liich may;

` for instance, be approximateiy ,'.Umgampere to rectional repeaters will be operated to spacing and both relays will connect high resistances, such as 22 and 222, in parallel between ground and hub 59. This will cause a spacing current which may, for instance, be approximately .024 ampere to iiow in the upper windings of relays and ||3 of the by-pass circuit and this will cause relays and |i3 to operate to spacing. The operation of relay il@ to its spacing contact ||2 will establish a circuit from ground through contact 2, Contact 19 and contact 16 to the double-space by-pass sending hub B0. From hub 6|! circuits extend through the bottom windings of each of the transmitting relays, such as relays 2M and 3M, of the various directional repeaters. In response to this each of the trans-v mitting relays, such as 5, 234 and 304, will be reversed to spacing which will transmit a space or break signal out to all interconnected lines and loops.

In order to insure that the break signal reaches all of the stations on the network it is desirable that this spacing or break signal be transmitted for an appreciable period and since relays Hi) and I3 will remain in the spacing condition only g momentarily during the interval while -both in coming space signals persist simultaneously the protraction of the spacing signal must be accomplished by special means. This is accomplished in the following manner.

When relay ||3 closes its spacing contact H5 ground is connected to the left-hand plate oi condenser l2|l in the by-pass circuit which causes condenser |26 to be discharged. This reduces the grid potential of tube |23 sufficiently to stop the flow of plate current in tube |23 which plate current normally flows through the winding of relay |25 to positive 13D-volt battery Ht. Relay |25 therefore operates under the iniiuence of its mechanical bias spring so as to close contact |2'i. This establishes a circuit from ground through contact |21, contact i9 and Contact 1B to hub B0, supplementing the ground that initially was connected to hub tu through contact ||2 of relay lill. When relays ||il and ||3 return to the marking condition at the end of the doublespace interval relay Il removes ground froml hub til and relay H3 removes ground from the left-hand plate of condenser |29 which begins to charge over a circuit which has heretofore been traced. i

After a predetermined interval of delay, which" can be adjusted between the limits of 50 and 500 milliseconds by means of variable resistance IIB, the left-hand plate of condenser |253 and the grid of tube |23 reach a potential sufficiently high toV cause the normal plate current to be reestablishedj in tube |23. At this moment relay |25 opens contact |21 and closes contact |25 removing ground from hub El) and thereby restoring the current in the lower winding of the transmitting relays, such as d, 2M and 304, of all directional repeaters to the marking direction. If all lines and loops are in the marking condition toward their respective directional repeaters the armatures of all transmitting relays such as relays 4, 204 and 304 will be operated to close their marking contacts. However, if one line or loop is still in the spacing condition all transmitting relays will remain inv the spacing condition except that of the directional repeater which is transmitting a spacing signal toward the regenerator which transmitting relay will be in the marking condition. The length of time which the spacing or break pulse should be transmitted should be slightly longer than the propagation time of a signal to the most remote station on the network.

Full-duplex loop feature The directional repeater is so designed that when its transmitting relay such as relay l is in the spacing condition, reception of a spacing signal from a line repeater to which it is connected will cause its associated receiving break relay such as relay to operate to the spacing condition. This enables the receiving break relay of the directional repeater to respond to spacing signals from the line repeater regardless of the position of the sending relay such as relay 4 of the directional repeater. This is achieved by means of the potentiometer circuit connected to the bottom windings of the receiving and receiving break relays in each directional repeater. Without this feature a spacing signal from a line repeater on reaching a directional repeater, the sending relay of which happened to be in the spacing condition, would fail to operate the receiving break relay to spacing. Thus, unless two spacing signals arrived almost simultaneously from the two lines involved, one would lock the other out. The double-space by-pass circuit would not respond in the manner desired without this feature which is called the full-duplex loop feature.

When a space signal from a line repeater is received by a directional repeater the sending relay of which is in the spacing condition, the receiving break relay operates to spacing due to a spacing current which may, for instance, be approximately .0585 ampere in its upper winding, which opposes a marking current which may, for instance, be approximately .0465 ampere in its lower winding. Under Such condition the associated receiving relay remains on marking due to a marking current which may, for instance, be approximately .070 ampere in its lower winding which opposes a spacing current, which may, for instance, be approximately .0585 ampere in its upper winding. It should be noted, however, that the receiving break relay and the receiving relay in a directional repeater both remain in the marking condition when the associated transmitting relay is transmitting a spacing signal and a spacing signal is received from a subscriber loop instead of from a line repeater. The break signal received from a subscriber loop opens the path through the top winding of the receiving and receiving break relays, such as relays and 2 so that, if it is received while transmitting relay 4 is on spacing, the armature of both relays 5 and 2 will be maintained on their respective marking contacts under the influence of the cur.- rent in their bottom windings which will be in a marking direction for this condition.

Goodnight feature When it is desirable -to temporarily remove a multiway regenerative repeater arrangement from service either for the periodic goodnight or for more or less extended intervals it may be 05 done by inserting plug |32, which has its tip conductor connected to its sleeve conductor, in jack ISI, at the test board. This opens the path4 which was formerly traced through the winding of relay 92, opening contacts 94 and 95 and dis- 70 connecting the power source 93 from motor 96.

The insertion of plug |32 in jack |31 establishesbranches which extend into each directional re 15y peater'such- asbranches 42, 41 and 52. This operates each of the transmitting relays, such as relays 4, 254 and 384, to the spacing condition. The transmitting relays are maintained in this condition as a goodnight signal which is transmitted to all of the interconnected lines and loops in the network.

Substitution of a regenerative repeater A spare regenerative repeater may be substituted for the regularly assigned unit in the following manner.

` One end of a two-conductor tip sleeve patching cord is connected to the regenerator jack E' in Fig. 2 or an idle unit. This disconnects the regenerative repeater regularly assigned to the: idle unitby opening contacts 6l and 68. The opposite end of the tip sleeve patching cord may be connected to jack 63 of the Fig. 2 in which the substitution is to be made. This disconnects the regularly assigned regenerative repeater by opening contacts 64 and 55 and connects the idle` unit through the tip sleeve conductors of the jacks and the patching cord.

A similar patch is made from motor control Tack 'l2 associated with the idle unit to hub B jack B9 of the assigned unit to provide goodnight control.

, Double-space by-pass circuit substitution A double-space by-pass circuit .may be substituted for the regularly assigned ley-pass circuit in the following manner.

One end of a two-conductor tip sleeve patching cord is connected to a jack such as jack 18 of an idle double-space by-pass unit. This disconnects t'he idle double-space by-pass unit from the concentration group to which it is regularly assigned by opening the contacts corresponding The opposite end of the patching to i9 and 89. cord is connected to the double-space by-pass hub jack 'l5 in the concentration group in which the substitution is to be made. This disconnects the regularly assigned double-space bypass circuit from its concentration group by opening contacts '.16 and Tl and connects the idle doublespace by-pass circuit through the tip sleeve patching cord and the tip and sleeve of jack 'I5 to the sending and receiving double- space bypass hubs 59 and 5!! respectively.

What is claimed is:

1. A half-duplex inultiway regenerative telegraph repeater system comprising more than two individual telegraph repeaters interconnected through hubs to a single one-way regenerative repeater unit, said system including means whereby but one of said individual repeaters may effectively transmit through said regenerative repeater to all or the others of said individual repeaters simultaneously through said hubs at any one time, and means in said system for effectively indicating, at remote stations connected to said multiway repeaters, a condition whereunder more than one of said individual repeaters attempt to transmit at any one 4time to said other individual repeaters, said latter means comprising instrumentalities for transmitting signals of protracted duration, substantially longer than the duration of normal signals, so as to insure reception at said remote stations.

- 2. A half-duplex multiway regenerative telegraph repeater comprising more than two individual telegraph repeaters connected through a sending and receiving hub to a single one-way telegraph. channel connected to any one of said,

individual telegraph repeaters, through said re ceiving hub to said regenerative repeater at a nrst time, means responsive to the reception of said signals from said individual repeater by said regenerative repeater for transmitting regenerated telegraph signals irom said regenerative repeater through said sending hub, through all of the others of said individual repeaters to telegraph channels connected to said other telegraph repeaters simultaneously and through said channels to remote stations, means connected to said individual repeaters for identifying a condition whereunder more than one of said individual repeaters attempt to transmit signals into said single regenerative repeater at said rst time, and means for eii'ectively indicating the attempted simultaneous transmission through said regenerative repeater to said remote Stations, said latter means comprising instrumen.-V talities for transmitting signals of protracted duration, substantially longer than the duration of normal signals, so as to insure reception at.

said remote stations.

3. A half-duplex multiway regenerative telegraph repeater comprising more than two individual telegraph repeaters connected through a single one-way regenerative repeater unit, means for transmitting telegraph signals from any one of said individual repeaters through said single regenerative repeater Aunit to all of the others of said individual repeaters simultaneously,

means connected to said individual repeaters forr identifying telegraph signals incoming from moreA than one of said individual repeaters simultae neously toward said regenerative repeater, and means connected to said individual repeaters responsive to the reception of said simultaneous signals by said individual repeaters for transmitting a characteristic protracted signal to ef-v fectively indicate the condition at remotel stations connected to said multiway repeater, said protracted signal of substantially longer duration than a normal signal.

4. In a telegraph system, a half-duplex mu1tiway regenerative repeater network comprising a plurality of half-duplex multiway regenerative repeater groups, each of said groups interconnectedby a telegraph channel to another of said groups, at least three individual telegraph repeaters in each of said groups, each of said individual repeaters in a particular group interconnected together through an individual hub circuit for each of said groups to a single one-Way regenerative repeater unit, means in said system responsive to the transmission of telegraph signals through any of said directional repeaters in a particular group into the corresponding regenerative repeater for transmitting regenerated telegraph signals through all other directional repeaters forming part of the same group simultaneously, means in said system for propagating said regenerated signals through said channelsv connected to said other directional repeaters to each other group forming part of said network, means including said regenerative repeaters: in said other groups for again regenerating said signals as they are propagated through each of said other groups, a double-space 'oy-pass circuit' connected to a particular one of said groups, means connected to said by-pass circuit for simultaneously receiving two spacing signal elements" generated in two groups of said network 17 different from said particular one group and means connected to said by-pass circuit for imposing a protracted condition on said system in response to said simultaneous reception.

5. In a telegraph system, a rst, second and third half-duplex multiway regenerative telegraph repeater group, each of said groups comprising at least three individual telegraph repeaters interconnected through an individual hub circuit to a single one-way regenerative telegraph repeater unit individual to each of said groups, a rst telegraph channel interconnecting an individual repeater in said iirst group With a first individual repeater in said second group, a second telegraph channel interconnecting a second individual repeater in said second group with an individual repeater in said third group, means in said system responsive to a telegraph signal received by any of said individual repeaters in any of said groups for transmitting regenerated telegraph signals to all other individual repeaters in each of said groups, a doublespace by-pass circuit connected to said second group, and means in said by-pass circuit for effectively passing through said second group a spacing signal generated in said third group While a spacing signal generated in said first group is passing through said second group.

6. In a telegraph system, a multiway regenerative repeater group, a double space by-pass circuit connected to said group, and means in said group responsive to the operation of said by-pass circuit for eiectively transmitting a characteristic signal indicating the simultaneous reception of two spacing signals in said group.

7. A multiway direct current half-duplex regenerative repeater group comprising a first directional repeater, a second directional repeater, and a single one-Way regenerative repeater unit interconnected -through a hub circuit, means in said rst directional repeater for receiving a spacing signal and impressing said spacing signal through said regenerative unit on said second directional repeater in a rst direction, means in said second directional repeater for receiving a second spacing signal incoming to said second directional repeater from a second direction, while said first spacing signal persists, and means connected to said repeater group for propagating a characteristic signal indicating the simultaneous reception of a spacing signal by said rst and said second repeaters.

8. A direct current half-duplex telegraph repeater, means in said repeater for transmitting a rst spacing signal through said repeater in a rst direction, a double-space by-pass circuit connected to said repeater, a transmitting device in said circuit, a time delay control connected to said device for controlling the transmitting of protracted signals from said device, means in said repeater for receiving a spacing signal incoming to said repeater from a second direction, While said rst spacing signal persists, means interconnecting said repeater and said by-pass circuit for impressing said second spacing signal on said by-pass circuit, and means connected to said by-pass circuit for propagating a protracted signal from said transmitting device in response to said second spacing signal.

9. A direct current half-duplex telegraph repeater comprising a receiving relay, a receiving break relay and a sending relay, an armature, a marking contact and a spacing contact on said sending relay, a telegraph channel extending from said armature through a line winding on said receiving relay and a line Winding on said receiving break relay in series, a biasing path extending from said armature through a biasing Winding on said receiving relay and a biasing Winding on said receiving break relay in series, a potentiometer connected to said biasing Windings, means comprising said potentiometer for controlling said receiving relay and said receiving break relay so that said receiving break relay will respond to a spacing signal incoming to said repeater from said channel while said armature engages its spacing contact and while said receiving relay remains unresponsive to said signal.

l0. A half-duplex repeater in accordance with claim 9 and a double-space by-pass circuit including a first and a second transmitting device and means connected to said devices for actuating said devices for intervals of substantially differing durations connected to said repeater for propagating said spacing signal incoming from said channel.

11. A half-duplex repeater in accordance with claim 9 and a double-space by-pass circuit comprising a timing device for protracting said spacing signal incoming from said channel.

12. A half-duplex multiway regenerative repeater, a double space by-pass circuit including signal element protracting means and means for flexibly interconnecting said repeater and said by-pass circuit.

KARL E. FITCH.

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

UNITED STATES PATENTS Number Name Date 2,334,551 Hanley Nov. 16, 1943 2,337,886 Hanley Dec. 28, 1943

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