US1632275A - Signaling system - Google Patents

Description

June 14 1927.

A. M. CURTIS SIGNALING SYSTEM Filed Feb. 14, 1925 4 Sheets-Sheet 1 June 14, 1927.

A. M. CURTIS smmme SYSTEM Filed Feb. 14 1925 4 Sheets-Sheet; 2f-

mum/0r: 41/674? M 60/772) June 14,1927;

A. CURTIS SIGNALING SYSTEM" Filed Feb. 14, 1925 4 Sheets-Sheet 3 Y '1,63 7 5 June 14, 1927 A. M CURTIS 22 SIGNALING svsma V Filed Feb.14, 1925 45heets-Sheet k -&

k k h Patented Jun e 14,1927. v I

AUSTEN m. CURTIS, or EAST bRanGE, NEwanns-EY, assieuoa, BY MESNE ASSIGN-I" nL icrmc oomramr, moonron'arnn, A CORPORATION or;

IENTS, TO WESTERN NEW 203K.

I .'1,53z,z75f UNITED STATES P ENT foFFicE.

SIGNALING s rsrnm.

Application filed February 14,1.1925. sen-a1'm .a,175. c 3 l I This invention relates to signaling sys f terns and more-especially it has todoW-ith an arrangementwhereby an operator WllO-lS in the act of receiving a message from along 5 submarine cable may signal or interrupt the sending of the operator at the distant end of sion of the message. v I

g It is essential in practically all telegraph 1 systems that a receiving operatonduring the act of receivin a message from a distant station. he capa le of signaling or interrupt.- ihg the sendin of the-operator at the distantstation'. uch' operations are commonly termed.blfeak or breaking service and areusually found necessary nr-handllngtelegraphic communications. VVl1ere a te'le graph circuit isshort enough so that the interruption of the circuit of the'receiveraffects'ithe current at the sending end ofthe; line, 3 or Where a long cable is' op erated duplex, no special means of ."breaking-in are required. Where a long submarine cable is operated simplex, the receiving operator ordinarily cannot interrupt the sending op'erator. This condition may frequently cause the loss of considerable time. While there are Ways in which electroma etic signaling devices may befnsed to a ena le the sending operator to be interrupted by'the receiving operator, these methods of operation are not entirely satisfactory. The" outstanding objection to the use of'electro-- magnetic devices connected to the signalingcircuit is the-large impedance, usuallin the form of' a choke coilin a leak or snnit circuit to the transmitter, necessary 'to prevent the normal'si'gnaling currents from atfecting the electromagnetic devices which 40 operate to communicate the break signal. The frequencies involved in the transmission of signals over long ocean cables do not-exceed a raw hundred cycles per second and many ofthe. important frequency components are frequently as low as a few cycles per second. The'use of such break systems isnot commercially--practicable' with such submarine cables, not'only due to, the fact that largeimpedances cannot be conveniently obtained, butalso, due to the effect of the leak circuitupon the signaling currents."

The core ofthe large impedancecoil inthe leak circuit introduces hysteresis which tends to disturb the shape. of the transmitted sigtransmission.

' submarine cable systems.

nals 'or otherwise interfere Withsatisfactory The principal object of the present invention is the indication of a'breaksignal to a distant sending operator in an efficient and I reliable manner,especially When the signal the cable at any time duri.ng"the transmis-.

jcomponentsare of loW frequency, as inlong Another object isthe repeating of speed telegraph signals transmitted over a line or cable of 'such'a nature that artificial balancing lines cannot well be maintained in adjustment. 4 I I Other. objects will be apparent from the following description and claims.

-' In carrying-out the invention in its pre-- {erred embodiment, there is connected to the signaling conductor or cable, the input circuit of an electron discharge devi'ceywhichv hasassociated -With it biasing'and delayed 7 7'5 tuning arrangements Which allow it to be operated only by; a signal of the'proper polarity and of a duration longer than occurs. in i the normal transmission of signals. An inv dicating device is accordingly operated to inform an"attendant that the -distant operator desires to reverse the direction of transmission.

The. invention further provides, When this break operation occurs, for the. automatic connection and disconnection of the transmitting and receiving mechanisms at the respec tive stations with the signaling circuit.

Another 'feature. of the invention is a re peater system arranged for repeatingsignaling impulses betweenassociatjed line sectionsprovided With means responsive to a break signal 'forcommunicating the break signal to .the distant operator andv for reversing"v i the connections of the repeater to permit the transmlsion of signaling impulses in the opposite direction. a

Heretofore =many different forms of repeating systems have beendesigned -for repeating telegraph signaling impulsesv from one line section to another but in order to permit the transmission of signaling impulsesiin either direction, the repeater ele-q loo ments mustsnecessarily be balanced to pre- I a vent what, is commonly termed singing. The commonest form of this type of repeater is a bridge arrangement designed to allow transmission in onedirection'and reception 1 inthe opposite direction without producing any appreciable interference. ifthe adj oining circuit. It has also been the consensus of opinion that greate r speed may be attamed by operating a circuit duplex, that is, the simultaneous transmission of signals in both directions over the same circuit but experience with permalloy loaded cables has prov'en'that at high speeds of transmission due to singing.

1 break signal.

Alsoto facilitate the operation line repeater. Referring ,be described. Extending even greater speeds may be achieved through simplex operation, at least with the types 0t balancing artificial lines. so far developed.

of the simplex system repeating apparatus is necessary for repeating the signaling impulses between the respective line sections without causing any of the objectionable features produced The repeater developed, for

the system described and claimed herein is capable of being associated with the line sections in a manner to permit the trans mission of signals in'either direction, which for changes in line conditions and may have its connections reversed from a terminal sta-' t1on to permlt the transmission or signals in either direction, by the transmission of a A better understanding of the invention may be had from the following description, taken in conjunction with the accompanying drawings, in which Fig. 1 illustrates one embodiment of the invention, Fig 2 shows a modification of the arrangement illustrated in Fig. 1, Figs. 3, l and'5' when arranged in the manner indicated in Fig. 6 show the break-in system applied to a midfor the moment to Fig. 1, the specific apparatus of the invention will now between two remotely situated stations, A marine cable which may be a continuously loaded submarine cable 5 preferably of the construction disclosed in patent to O. E. Buckley, 1,586,874, issued June 1. 1926. The

cable 5 consists of twin cores for a short.

distance fromeach end, one core of which extends through the entire length of the cable and connects the signaling apparatus at the respective stations. The cores extending from each end of the cable terminate in sea earths 7 and 8, respectively.

Located at station A is a-transmitter' T and a receiver R, which is connected between the sea earth 7 and the signaling core 6,

through an amplifier by means of a switch 9. The switch 9 has three points of connection, one each for connecting the transmitting and receiving mechanisms with the signaling conductor v6, and one for connecting a local source of current therewith. Connected in parallel with the transmitter T and ground is the input circuit of a three-elementelectron discharge device .10. The electron discharge device 10' has a negative grid battery of the order of 60 volts, in any event higher than the maximum instantaneous voltage impressed on the cable due to the operation of the transmitter T. For this reason no current from the. transmitter T can flow through the grid circuit of the device 10'to earth duringnormal operation of the system. The plate battery which is of the order of 106voltsmay be-too low to allow any plate current to flow while the transmitter is not in operation or merely low enough to keep the plate current Well below the operating current of relay 11. Moreover, the plate voltage is not of sufficient value to cause the flow of space current when negative impulses are being transmitted. However, when positive impulses are transmitted the plate current flows for short intervals during the peaks of the positive imulses. Connected in the output circuit of the electron discharge device'is a slow acting relay 11, which controls a dashpot relay 12. y The current fiowingin the output circuit of the electron discharge device 10 due to the normaloperation of the system is usually not sufliclent to operate the slow actlng relay 11. However, should it operatemomentarily the period of operation is insufiicient .to effect the operation of thedashpot relay 12 controlling through its contacts the operation of a hell or other indicating device '13.

Equipment similar to that just described is also located at the station E and for the sake of brevity further description isnot given. '7

Assume that the station A is transmitting a message to station E. in which event the switches 9 and 14 at the respective stations will be in the positions shown in Fig, 1 of the drawing. Wishes to break or interrupt the sending. of the transmitting operator the switch 14 is moved to disconnect the receiver R from the signaling conductor 6 and engage contact 15, which applies a continuous positive voltage to the signaling conductoi'6. The

voltage thus applied gradually builds up at station A and by neutralizing the grid hattery, of the device 10 increases the potential of its grid. electrode to a point where its normal space current is materially increasedf Although the normal space current is still being varied over a wide range due to the operation of the local transmitter T, its

If the receiving operator the energization of slow'actingrelay "11..

' alarm bell 13 or other indicating'fdevice. The operator at station A upon hearin" the bell 13 is aware of the fact that thez receivingi operator at station B desires to reverse'the/ "anaemia average value is sufficiently high to cause The slow acting relay 11 now remains close for an appreciable interval,v which" permit the operation of the ,dashpot relay-12 and the closure of its contacts for operating I direction of transmission-.' The switch!) is then thrown to'disconnectthe transmitter T and connect the receiver R with thesignaling conductor 6. Likewise, at station B,

switch 1 4 is thrown to engage contact 16 for s associating the transmitter I nalingconductor 6.

with the sig- Inasmuch as similar apparatus is located at each station, the operator at station A now inthe act of receiving messages from station B may interruptthe sendingand reverse the'dire'ction of transmissionin amanner similar to that previously described,

Referring now to Fig.2, the modification illustrated in'this figure will' be described.

The arrangement shown in this figure-is fun- 'damenta11ythe same as that described in connection with Figs- 1, except for the provision of certain devices for effecting the automatic connectlonj and disconnection of the transmitting and receiving-lnechanisnis with the signaling conductor. vv-ln'pla ce of operating" a bell or other signaling device the dashpot relay 12 of Fig. '2 closes at its contacts the circuit of a relay 28. This relay upon beingenergized establishes through its own contacts and; a-manuallyoperated key 27 a locking circuit'for itself, and alsodisconnects. the transmitter T and connects the receiver R with the signaling co'nducj I tor 6.

At the station B, certain modifications spring operatedkey or switch"20which"is used to commence the train o-fopera'tions renaling. It is moved in the directionfof-the sulting 'in reversing the direction'of.--sigpleting the energizing circuit "of relay 22.

This relaylocks through its own contact and the-purpose ofo" ening t e locing cir'cuit's' of relays 25 "an 28, ;thereby restoring the}. 'systemito normal. Y r i f x-Th arrangementdisclosed in.Figs.-f3, 4f]

connects through its front contact a positive .voltage from battery 26 to the signaling conductor '6. The operation-of the relay 22 also disconnects the receiver R from the signaling conductor 1 6. Just before the switch- 20 reaches its normal position, contact 24; isengaged and closes momentarily a 'circuit inculding the winding of relay 25; This relayis thereupon energized and opens '-the locltingcircuit of relay 22, which disconnects the source of current 26 from the -the windingthereof to ground."

sages from'station B. V c I v continues its rotation, contact 24 1sengaged,-whereuponresignaling conductor and extends this conductor to the armature 'ofirelay 25. This and vdisconnects the receiver Rand connects the" transmitter T to the signaling conducto'r 6; r

thatmessages are being; transmitted from station A .to station B andthat the operator at station E desires to interrupt thesend- The B operator would 'then actuate su-me substantially ten seconds incompleting its operation; Contact 21 is'first'engaged ayjj also lockedup through its own con- 3 5- Assume for ithe purpose of illustration ing andreve'rse the direction of transmis sion. ,keyor switch'20, which is adjusted to confor causing the energization and locking up of;rela y..22. The locking circuit for this relay may be traced from' grounded battery,

contacts offkey 23; contacts of relay 25, left I hand contact and armature of rela 22 and clay 22 also connects the source of current 26 with the signaling conductor 6. i As described in connection with'Fig. 1 the'increased positive potential impressed on the signaling conductor. 6 dueto the connection of a similar operationof the slow acting relay 11. Relay 11 is maintained operated-for an interval source ofcurrent therewith causes sufficient j space current to flowinthe electron discharge device. 10 at station At'o effect the suflicient to permiltslow acting relay 12 to. close 1ts contacts andcause'the energi'za, tion of relay 28and the-illumination of signal lamp 29. This relay, is lockedfu'p;

through its owncontacts' and disconnects the transmitter- T from the signalin "con-B ductor 6 and connects the receiver R t "eretol The app r at statio .A is now. i n. the

proper position for the. reception m es'-;"

As the key or, switch 20 sigr'ialir'ig conductor 6. Messages may now a betransmittedrronr station B to station A.

It should be notedin the arrangement'jnst described that the transmitting and receiv x ing mechanisms are automatically {con-z nected; and disconnectedwith. and from the signaling conductor upon the transmission .ofa break signal; Keys 23 and 27 ats'tations Band Afrespectivel .7 are rovided for nected by means offsu bmarine cables 30 and '66, respectively, the station Y serving as a mid-line repeater. for repeating impulses 1 transmitted in" both directions. For example,'station X may be designated as New: York; station Y as theAzores and station Z as Rome between which points it is desired to transmit messages.

The apparatus located 'at stations X and Z is the same. For the purpose of brevity a detailed description of the apparatus at' but one of'these stations will be given. It is noted, however, that similar apparatus at these two stations is represented by the same "reference character with the prime indice added. V

Referring to Fig. 3, there is provided a shaping amplifier A of the type. described in detail in my Patent 1,586,97 0, issued June 1, 1926, combined with a shaping network N of the type described in my Patent 1,586,972, issued June 1, 1926. In transmittingcurrent impulses over a long cable, lOW

- frequencies are attenuated much less than the high frequencies and thelow frequencies are also retarded in phase more than the higher frequencies. The network N is designed to correct in part at least, the received impulses forphase shift and for attenua tion, and'at the same time provides a high:

impedance termination for the signal frequencies.

The-input circuit the first amplifier tube 34:- is connected tothe secondary winding of 'the transformer 35, the primary coil of which is included in the first shaping network N. Between the output circuit of the amplifier tube 34 and the input circuit of the amplifier-tube 36, there is provided a shaping network so designed as to further compensate for the attenuatlon of the signaling impulses. Between the output circuitof the amplifier tube 36 and the input circuit of theamplifier tube 87 there is a second network which is designed to reduce densers 40-40 and shunt condensers 41l1. are provided between the different stages as shown Ihe change from sending toreceiving positions and vice versa' is accomplished by means of a relay 50, which is provided with apair ofavindings63 and64. These winch ings are energized'in accordance with pre-' determined conditlons for associatlng .the

transmitter T and the receiver R with the signaling conductor 31 of the cable .30.

Vhen signaling systems in which the received signaling current Waves are shaped and amplifiedbefore effecting the operation of the receiving apparatus, areused for al heeaave ternatelysending and receiving, it is neces sary to provide some means for protecting the receiving apparatus from the flow of excessive currents occurring when the cable is disconnected from the sending apparatus and connected to the receiving apparatus atthe end of the signaling period. After the transmitter has been disconnected from the cable and connected to earth there flows from thecable a current which is due to the'combined action of the earth current flowing in the cable caused by difliereht potentialsof the earth at the respective terminals and the flow to' earth of the electric" -charge absorbed by the cable dielectric during the sending period' This absorbed charge may take several minutes to completely disappear and there still remain the earth currents which are usually capable of producing av potential between the cable and earth-far in excess of the normal voltage of the signal for which the system is designed;

If the input circuit of the amplifier isicon- U nected beween the cable'and' earth and the direct connection between the cable and earth removed therewill result a current im- 4 pulse of many times the voltage of the normal signaling current and containing abnormally high frequency components. Since the amplifier and its input circuits are .designed so that up to a certain frequency amplification increases in proportion to the frequency. the, amplified impulses upon reaching the receiving mechanism may be of sufiicient amplitude to seriously damage the apparatus. Furthermore, the high voltages impressed. upon the input circuits of the later stages of the amplifier \vill ialso materially change the charge of the condensers used for couplingbetween stages, and by the change of grid mltages-thus produced, the amplifier will be rendered inoperative for several minutes or until'thenormal grid voltages are again established by the charge and discharge of several large condensers through high resistances. In view of the circumstances thus. encountered, switching means is provided for protecting the ampli: fier against excessive current impulses. This particular feature of the invention is accomplished upon the operation of relay 51, which serves to short circuit resistance 52,

and the primary section of'the auto-trans- I former between the first and second stages. It might be. noted here that the relay 51 is normallybiased to its open .circuit position. f a J Also-located at station X is a suitable key 55 which controls the application of the positive potential to the. signaling conductor 31 for the purpose of interrupting the send ing of an operator located at station Z and of reversing the direction oftransmission.

As described in connectionwith Figs. 1 and 2, a three-element electron discharge. device i 60 controls. a slow acting relay (il which scribed in connection with-the arrangement in turn controls'a dashpot relay 62. The electron discharge device 60. serves the same purpose as described in connection' .with Figs. 1 and 2 and further detailed information thereof is believed unnecessary Coming now to Fig. 4l,' which-illustrates the repeating apparatus located at'station 'Y or the Azores, it is seen that the cables- 30 and 66 terminate at this station. As deshown in Fig. '3, a shaping network C and an amplifier D are provided. .The shaping i network C isconnected with-the amplifier tube 73 through a shielded transformer 72 in a manner similar to that shown in connection with Fig, 3. Likewise, the amplifier tube 74 is connected with the amplifier tube 73. Although but two stages of amplifica tion have been shown,'it is, of course, ob-

- vious that further stages, may be added with- Out-Kdeparting from" the spirit and scope of.

this invention. It may even be'desirable to employ, an amplifier possessing the same characteristics as the one described in corn nection with Fig. 3, but for the purpose of brevity the amplifier disclosed is believed to be suiticient for thepurpose of illustrating this invention.

The input and output circuits of the shaping network C and the amplifier D are arranged to be switched between the signaling conductors of the respectivelcables 30 and 66,-through the operationofa multi-contact relay 77. This relay has two windings and is'arranged to be operated upon the comple tion of predetermined circuits. lVhen transmission is taking place from station X to station Z through the repeater Y, the input circuit ofthe shaping network 0 is connected between thesignaling conductor 31 ofthe cable 30 and thesea earth through contacts 75 and 76. Likewise, the output cir- 'c-uit of the amplifier D is connected between the signaling conductor68 and the sea earth 67 of the cable 66 through contact 7 8.

In order to permit thereversal of the di rection of transmission and the communication of a break signal to the then transmitting operator, suitable mechanism is provided for accomplishing these features without the introduction of any appreciable distortion of the transmitted signals. This mechanism comprises an electron discharge device 81 which has its input circuit operatively connected with the signaling conductor 31 of the cable 30. As described in connection with Figs. 1 and 2, the electron discharge device has-a negative grid battery of the order of 60 volts, in any event, higher than the maximum instantaneous voltage impressed on the cable due to the-operation of the transmitter. For this rea-on no current from the transmitter or signaling conductor 31 can flow through the grid circuit of the tube to earth during the normal transmission of signalingfimpulses There is also connected in the plate circuit of the device a battery of approximately 100 volts,which is too low to cause any appreciable plate ourof negative signaling impulses but when positive signals are transmitted the plate current flows over short intervals during the peaks of the positive im ulses. -'There is 7 connected in theoutput clrcuit of the electron discharge device 81, a slow acting-relay 82, which may momentarily close its. contacts under certain conditions, but-not for an interval of time suflicient to allow dashpot relay 83 tooper'ate. There is-arranged on. the armature of the dashpot relay 83 a pair ofinsulated brushes 88 and 89 whichsuccessively engage segments 86 and 87 during its" travel. The armature ofthis relay also effects the closure of contacts -90iwh en in its extreme uppermost. position. When the ar-'.

mature ofthis relay is in its normal unactu- 'ated. position or the position shown in the .break signal in accordance with the direction which messages were-previously being transmitted.

A better understanding of the invention 195 may be had from the following detailed description of the operation of the system. As

sume. for the purpose 'of illustration that signals or messages are being transmittedfrom station X to station Z through the midw 8 line repeater Y. Further assumethat the multi-contact switch 77 at station Y is in the position shown. When the apparatus is connected to the respective cablesin the manner shown signals transmitted from. the I transmitter T at station X pass over the signaling conductor 31 of the cable 30, extreme left hand back contact of relay 80,- contact 75 of multi-contact switch 77,

the circuit of the input shaping network C, contact 76 of the multi-contact switch 77 to ground at the sea earth 65. .T-he signals thus received pass through-the shielded transformer 7 2, are amplified and'corrected in accordance with the manner previously described and pass over a circuit extending from the output circuit of the amplifier 74, contact 78 of the multi-contact switch 77, contact 94 of relay 91, conductor 68 of the cable 66 to station Z. The impulses upon W 70' rentto flow during the normal transmission that the operator at station Z desires to break,

the operator at station X and reverse the directlon of transmission. Accordingly. key is actuated for performing several sequential operations. Immediately that key 55 is moved from as normal position contact 59 is closed for momentarily grounding-the input circuit of device thus preventing its operation and the energization of relays 6t and 62. \Vhe'n contacts 56' and 57 are closed through the actuation of the key 55. a source of current is' applied to the signaling conductor 68 of the cable 66,' through the contact56 and key 55. The closure of contacts 57 causes the completion of an energizing circuit for relays 50 and 51'. This energizing circuit may be traced trom the positive pole of batcharge absorbed tery, winding Set of relay 50, contacts 57, lower winding of relay 51 to terminal of the same battery. Relays 50 and 51 are thereupon caused to reverse the position of their armatures, relay 50 disconnecting the input circuit of the shaping network N and amplifier system A. from the cable and connecting thereto the transmitter T. while relay 51 which is normally biased to the open circuit position short circuits a portion of resistance 52' and the primary winding oi the interstage auto-transformer for protecting the amplifier from excessive current impulses resulting from electric by the cable dielectric during the sending period, as is described in my Patent 1,586,971, issued June 1, 1926.

The connection of the current source through contact 56 to conductor 68 ot the cable 60 causes suiiicient space current to flow through the electron discharge device on Y to produce a current 81 located at stati flowing in the output circuit thereof over a period to cause the operation oi? slow acting relay 8'). ltolay 82 is thus energized for causing the encrgization and operation of the dashpot relay 83. .The armature ot' the dashpot relay 853 is designed to move in the forward direction slowly but upon deenergization restores to its normal position quickly. Immediately that the armature of the relay 83 begins its forward movement. contact E i is closed which produces no change in the circuit connections as the relay 92 is already in the position to which it would be moved upon the completion of the circuit through the contacts 84: and 85.

the election discharge the negative As the armature of the-relay 83' continues its travel segment 86' is engaged by brush 89. Upon the engagement of the brush 89' with the segment 86' an energizing circuit. is completed including the right hand winding of relay 92 and the winding of relay 80. This circuit may be traced from the positive pole of battery, right hand winding of relay 92, winding of relay 80, brush 89', segment 86' to the'other terminal of the battery. Relays 80 and 92 are energized over cuit just traced. The former connects through its right hand front contact ground with the grid electrode of the electron'discharge device .81, thereby preventing its operation, while at its back contact it disconnects the circuit extending front the conductor 31 of the cable 30 through the contact of the multi-contact switch 77 to the input circuit of the shaping network C and connects at its front contact a source of current for transmitting a positive impulse to station X over the signaling conductor 31, the purpose of which will be described shortly. Relay 92 closes its contact, short circuiting the resistance and the primary winding of' the interstage auto-transformer for the purpose of protecting the amplifier as previously described. The armature of the relay 83 continues its travel. disengag ing brush 89 with segment 86 and causing the engagement of brush 88 with segment 87. Upon the engagement of the grounded brush 88 with segment 87. which occurs some little time following the application of the source oi current through the'operat'ion ot'relay so that the impulse transmitted has had sufficient time to eti ect the operation of the apparatus at the station )1. the charge on the signaling conductor I'll of the cable 30 is allowed to discharge. By grounding the signaling conductor 31 in this manner the charge absorbed during the transmission of the signaling impulse just referred to is allowed to drain oft. thus restoring the cable to a neutral position. Following the disengagement ot the brush S8 with segment 87, contacts 90 are actuated by the armature of relay 83. The closure ot these contacts establishes an energizing circuit including the lower winding oi the multi-contact relay T7 with a source of current. This relay is thereupon caused to reverse the position of its arn'iature, causing the opening of the previously engaged contacts and the closure of contacts 98, 99- nnd 100. The engagement otthe contacts just emimerated causes the reversal of the connections of the shaping network C and the amplifier D with respect to the conductors 31 of the cable 30 and the conductors 68 of the cable 66, re spectively. In other words, the input circuit of the shaping network 0 is new connected between the conductor 68 and the sea earth ($7 of the cable 66, while the output the cirreversing the connections ofthe conductor 31 of the cable 30.

In' order .to clarify the description the sequence of operation occurring at the -re-j peater station Y will now be outlined. Thev application of the positive potential at station'Z causes current to flow in the output circuit. of electron discharge device 81. Relay 82"is energized and dash-pot- 1'ela'y'83 operates through the control of relay -82. Dash-pot relay 83' first closes contact 84 closing a circuit through the left hand winding of relay 92 but nothing happens as this relay is already in this position. After contact'85 is opened, segment 86 is engaged by brush 89' closing the'circuit through the right hand winding of relay 92 which closes its contacts thereby rendering the amplifier ineffective. Brush 89 dis'engages segment 86f and brush 88 engages segment 87- groundingthe conductor 31. Finally, -after brush 88' has disengaged segment 87,1contact 90 is closed energizing relay 7? for the shaping leased, it being only necesary that it be operated for a short period of time, the source of current applied to the conductor 68 through contact 56' is removed and the cable is discharged by the momentary grounding caused by -operation of contacts 58 and 59 so that space current through the tube 81' no longer flows. The relays 82 and 83' are thereupon released, the armature of the'latter justbefore reachingits normal position closes the circuit including contacts :84 and 85 and the armature of this relay. Since contact 84f is at this time closed, an energizing circuit is established,

including the left hand winding of relay 92,

, which is energized for removing the short circuit about the resistance 93. It should be noted that relay 92 is an unbiased polar relay, which remains -in theposition to which it- Yas last operated. The impulse applied to the conductor 31f -i'esulting jfrom the operation of relay 80 is impressed on the input circuit of the electron discharge device atstation X.j Inasmuch as this impulse is applied for an appreciable interval of. time, the current in the output circuit is allowed to build up to' a sufficient value for effecting the operation of slow acting relay 61. ;This relay closes at v its contacts the energizing circuit tor-dashpot relay 62. Dashpot' relay 62 in closing its contacts causes the energization of relays 50 and -51. The latter relay short circuits the resistance 52 and the primary coil of the from the conductor 31 of the'cable 3O and circuit of the amplifier D is associated with the relay 5 0 'disconnects'the transmitter T connects theinput circuit of the, shaping network Nthereto. As setio'rth in app'll} desirable that the shortc'ircuit be placed on v the'amplifier" slightly in advance otthe transfer from transmitting to receiving. In the "circuit arran ement disclosed, the orderin which this ta (es place will depend upon the time constants of relays 5'0 and cants .co ending application, Serial No. 7 732,900 fi ed Aug. 19, 1Q24,"it is generally.

'51 and the adjustment of the relay contacts. 1

Ifthese relays'are adjusted soth at 51 0})- crates, in advance of 50, the short-circuiting of the amplifier will take place priorjto'the .applicationof the receiving network N'to the conductor 31; However, the 1 adjustment .of these relays may be such that their operation will take place simultaneously if desired., l/Vhen-'1'elay at station Y re- ;lea ses its armature, the-source of current applied to the conductor 31 of the cable 30 is disconnected,whereupon the current in the output circuit ,of-electron discharge [device 60 diminishes to a po'int'where relay 61 releases itsarmature, consequently dashpot relay62 is released, which opensat its contacts the energizing circuit of relays 50 and 51. The

former relay is arranged to remain in its aotuated position Iupon the opening of this circuit, but the latter relay is normally biased to the open circuit position or the position shown in the drawing upon the 3 opening ofthese contacts. lVi'th' the operation. just described completed, the transmitting and receiving mechanisms at the respective stations are connected and are associated with the rei spective conductors of the connecting cables 1n .amanner to now permit the transmission of-signalsfrom station Z through the repeater Y tostation X, which is the reverse direction to that forwhich the apparatus was previously connected.

-The invention has been shown. and described as-applied to a particular type of system, but it is obvious that various modifications may be made without departing from the spirit and scope of the present invention.

What is claimed is:

1. In a signaling system, =transmitting and receiving mechanismslocated at the respective stations, a leak circuit associated with saidtransmitting mechanism, a device substantiaily free of hysteresis included in said leak circuit and unresponsive to the operation of said-transmitting mechanisn'i, and means controlled by the receiving operator interstage auto-transformer for protecting for effecting the operation of said device.

the amplifier against the electric charge ab sorbed by the cable during the transmission of the impulses which effect the operation of electron discharge device 60, while 2. A signaling system comprising a submarine cable incapable of c'liiciently transmitting signals involvingfrequencies of more than few hundred cycles per second,

7 receiving mechanisms associable with a extending to a remote station,

transmitting means at each terminal for transmitting such signals, a circuit inshunt to said transmitting means at each terminal containing means responsive to a break signal'trom the other terminal, said shunt circuits being of such high impedance and so free from hysteresis that signals are not distorted thereby.

' In a signaling system, transmitting and 91" naling path an electron discharge device responsive to a signal from a distant receiving operator, said device representing to the signaling currents a high impedance at normal signaling frequencies whereby said signaling currents arenot appreciably distorted nor rcduced'in volume, and means controlled by said device for indicating to a sending operator adesire on the part of the receiving operator, to reverse the direction of transmission.

4. in a Signaling system, transmitting and receiving mechanisms associable with a sig naling path extending to a remote. station, a device responsive to a signal from a, dis tant receiving operator to indicate to a sending operator a desire on the part. of the receiving operator to reverse the direction of transmission, said device representing to the signaling currents a high impedance at the frequencies of the normal signaling trequcn said device for communicating a break signal to the transn'iitting operator.

6; In a signaling -vstem, a continuously loaded cable, transmitting and receiving mechanisms associable with said cable, a device associated with said cable, which in response to a prolonged positive impulse impressed on the cable will permit a current to flow in an output circuit of said device, and means operated when current is allowed to tlow in the output circuit of said device for an appreciable period ot time for communicating a break signal to the transmitting operator.

1. In a signaling system, a continuously loaded cable, transmitting and receiving mechanisms associable with said cable, an

'pressed on the .cable,

distort or interfere with the I electron discharge device-associated withsaid cableand responsive to a-prolongedpositive impulse impressed. on the cable, and means controlled by said electron discharge device for automatically reversing the connections of the transmitting and receiving mechanisms with said cable at the transmitting stations. 8. In a signaling-system, a continuously loaded cable, transmitting and receiving mechanisn' s associable with said cable,'a device associated with said cable and responsive to a prolonged positive impulse i111 and slow-acting electromagnetic means controlled by said device for automatically reversing the connections of the transmitting and receiving mechanisms with said cable;

9. A signaling system comprising a signaling path, transmitting and receiving mechanisms associable with said signaling path, an amplifier connected to said receiver, means responslve to a'break signal transmltted by a receiving operator for reversing the connections of said transmitting and receiving mechanisms Wltll said signaling path, and means controlled by said means for bridging alow impedance "circuit across the amplifier to prevent excessive current impulses at the time of connecting the receiving apparatus to the signaling path.

10. Asignaling system comprising a signaling path, transmitting and receiving mechanisi s associable with said signaling path, anamplifier connected to said receiver,

means including an electron discharge device responsive to a prolonged positive impulse transmitted by a receiving operator for reversing the connection of the transmitting and receiving mechanisms with said signaling path, and means controlled by said device tor bridging a low impedance circuit across the amplifier to prevent excessive current impulses at the time of connecting the receiving apparatus to the signaling path.

11. A submarine cable/repeating system for repeating high speed telegraph signals comprising a one way repeating device, switching means for reversing the relationship of the repeating device with-respect to the cable, and means unresponsive to normal signaling impulses and controlled from a remote station over a section. of the cable for controlling said switching means for changing the direction in which said device will repeat.

12. A signaling system comprising a signaling conductor and divided into sections, repeating ap iaratus internuidiate said sections for repeating impulses from one sec.- tion to another said repeating apparatus including an amplifier, means operated to associate said amplifier with said line sections for transmission of impulses in either direction, means responsive to a special signal for operating said means to reverse the connections oi said amplifier with respect to said sections, and further means operated upon the receipt of a special signal for bridging a low impedance circuit across the amplifier to preventexcessive current impulses at the time the connections of the amplifi are reversed.

l3. A signaling system comprising a signahng conductor divided into sections, repeating apparatus intermediate said sections for repeating impulses from one section to another said repeating apparatus including an amplifier, means operated to associate said amplifier with said sections for transmissionof impulses in'either direction, an electron discharge device responsive to a special signal, and means controlled by said device for operating said means to reverse the connections of said amplifier with respect'to the sections of said conductor.

14. A signaling system comprising a signaling conductor divided into sections, re-

- peating apparatus intermediate said sections for repeating impulses from one section to another, said repeating apparatus incl 'ng an amplifier, means operated to associate said amplifier with said sections for transmission of impulses in either direction, an "electron discharge device responsive toa special sig nal, and a relay controlled by said device for operating said means to reverse the connections to said amplifier with respect to the sections of said conductor.

A signaling system comprising a signaling conductor divided into sections, re-

peating apparatus intermediate said sections for repeating impulses from one section to another said repeating apparatus including an amplifier, means operated to associate said amplifier with said sections for transmission of impulses in either direction, an electron discharge device responsive to a special signal, a relay controlled by said device for operating said means to reverse the connections to said amplifier with respect to the sections of said conductor, and further means also pperated by said relay for bridging a low impedance circuit across the amplifier to prevent excessive current impulses at the time the connections of the amplifier are reversed.

16. In a signaling system, a conductor divided into sections, receiving and transmitting mechanisms at each of said stations, repeating apparatus intermediate said sections including an amplifier, means for associating said amplifier with said sections for transmission in either direction thereover,

an electron discharge device located at the same station as the repeating apparatus responsive to a special signal, means controlled by said special signal for transmitting to the adjoining section a prolonged impulse and for reversing the relationship of said amplifier with respect to said sections, and means at the distant stations responsive to the pro-' longed impulse for reversing the connections of said transmitting and receiving mechanisms with respect to the signaling conductor.

17. .In a signaling system a conductor di vided into sections, receiving and transmitting mechanisms at each of said stations, repeating apparatus intermediate said sections including an amplifier, means for associating said amplifier with said sections :t'dr transmission. in either direction thereover, an electron discharge device located at the same station asthe repeating apparatus responsive to a special signal, means controlled by said special signal for transmitting to the adjoining line section a prolonged impulse and for reversing the relationship of said amplifier with respect to said sections, means comprising an electron discl'large device re sponsive to the prolonged impulse, and means controlled by said device for disconnecting the transmitting mechanism and' connecting the receiving mechanism to the signaling conductor.

18. In a signaling system a conductor divided into sections, receiving and transmitting mechanisms at each of said stations, repeating apparatus intermediate saidsections including an an olifier, means for associating said amplifier with said sections for transmission in either direction thereover, an electron discharge device located at the same station as the repeating apparatus responsive to a special signal, means controlled by said special signal for transmit- V ting to the adjoining section a prolonged impulse and for reversing the relationship of said amplifier with respect to said sections, and further means also controlled by said device for protecting said receiving equipment against excessive current impulses resulting from the transmission of signaling impulses over said signaling-conductor.

19. In a signaling system, a submarine cable, a transmitter associated therewith having a direct current resistance that is extremely high compared to that of said cable and a deviceconnected in shunt to said transmitter, said devicehaving an impedance that is extremely high compared to that of the cable for currents of signal frequencies but which will respond to a prolonged positive impulse on said cable to disconnect the transmitter therefrom and connect a re- --ceiver thereto.

. I nc tam auxiliary-one-waly s\vi 'tching' mechanisn l" for comprising aone-way message repeating de'- repeatingdevice means fol v causing, atall times, at least pm .11 fifllllfallXllldly devices. to be in parallel with said message repeating device,'-a-nd phanging-the relationship ,of said message repeating device to thdcable, said. switchmg mechanism be- 'my name fill-clay ofFebl'uary', A.

ing under the controlof atle as t one 'Qf saicl ailx'lliary rlevlces,-salrl auxiliary (levic'e heing of high impedance. and substantially 1'0- act'lonless at signal frequencies,

uln witness whereof, I hereunto subscribe- D.

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