US2193811A - Signaling system and apparatus - Google Patents

Description

,Mgrch 19, 1940. I 'R. F BL ANCHARD EIA 4 3,

SIGNALING SYSTEM AND APPARATUS 051mm; Filed Feb. 25, 1936 '7. Sheets-Sheet 1 REBLANCHARD W.B.BLANTON RNEY R. F. BILANCHARD ET AL ,8 1 r SiGNALING SYSTBI AND APYARATUS Original Filed m, V25, 1936 7 Shots-Sheet 3 Rf. BLANCHARD BY W.B. BLANTON \HL. BROWNE MGBW AT F Q m Ev 0 RNEY Much 1940. v R. F. BLANCHARD ET AL 2,193,811

smmmne sYs'mu mm Arrmws Original fined Fob. 25, 1935- 7 Shots- Sheet 4 v D W W 1 Q 535350 mmBLM m 1 F 4 W maw m J 2d .1. F :7 o

R. F. BL'ANCHAIRDYETAL 2,193,811

- smmmme s sma AND APPARATUS Original Filed Feb 25, 1936 7 Sheets-Sheet s l LTRS SHIFT s FIGS sun-"r e-- o(|234-9) v 7- |(234s--o) a- LTRS SHIFT 9- w BLANK lO-BLANK INVENTORS v R.F. BLANCHARD W.B.BLANTON BY H.L.BROWNE s 5 f/d ATT RNEY 1 March 1940- R. F. BLANCHARD ET AL 2,193,811

SIGNALING SYSTEM AND APPARATUS Original Filed Feb. 25, 1935 '7 Sheets-Sheet 6 'lllllll IL u 1940- R. F. BLANCHARD El AL ,193,

SIGNALING SYSTEM AND' APPARATUS I Original Filed Feb. 25, 1936 7 Sheets-Sheet '7 I A RECEIVING B lNTERMEDlATE I C SENDING REPERF. 8 XTR umTs v SWITCHBOARD 200 I 55m 7 III III 204 201 ala INVENTORS RF. BLANCHARD W-B.BLANTON ATT RNEY Patented Mar. 19, 1940 SIGNALING SYSTEM AND APPARATUS Rolla F. Blanchard, Westfield, N. J., and William B. Blanton, Merrick,

and Harry L. Browne,

Brooklyn, N. Y., assignors to The Western Union Telegraph Company, New York, N. Y., a corporation of New York.

Application February 25. 1936,'Serial no. 65,702

I Renewed October 18,1939

33 Claims.

relaying messages through one or more oflices or stations.

In general terms the object of the invention is to expedite the transmission of'signals, such as message groups of signals used in telegraphic communication, where a direct channel is not available between the originating and final stations, as for example in communication between a branch telegraph oflice connected to a central ofiice and'a remote oflice connected .to the central oflice through one or more inter-city channels; and furtherto provide a method of and apparatus for automatically retransmitting groups of code signals, such as permutation code signals received from a branch or subscriber's oflice, over a selected one of a plurality of circuits or channels terminating in the main or central telegraph oflice under the control of an operator or attendant in the latter oifice. The word channel is used in a broad sense to include a metallic or phantom circuit, a channel of a multiplex or carrier current system, etc.

In printing telegraph systems, it has been common practice in the case of messages originating in branch or subscribers offices connected to a main or central ofiice in which inter-city trunks terminate to receive the messages on printers at the central ofiice, transfer the printed message to a sending position having access to the outgoing trunk or channel and retransmit the message manually. This method involves a delay or ofiice drag-in many instances but has the advantages that the transmission is completely super-vised, the messages sent over each outgoing channelfihay be numbered consecutively to 'facilitate tracing lost or mutilatedmessages and the routing of messages may be altered at any time as required by trafiic conditions on the outgoing trunks from the central office or apparatus pose service signals, such as consecutive numbers,

between groups of message signals so that supervision, routing and numbering of messages follow present practice although manual handling and retransmission are avoided. As will be apparent, the numbering of messages may be omitted if desired and certain features of the invention are not limited in their application to printing telegraph systems of this particular character.

A further object of the invention is to provide a printing telegraph exchange system in which messages originating in branch offices' may be relayed through a switchboard or'other switching apparatus at the central office either to startstop printers of other local branch offices or over multiplex channels terminating in said central ofiice.

A further object of the invention is to provide in a printing telegraph system having a main or central ofiice and one or more branch ofiices, receiving-storing devices such as reperforatortransmitters at the central ofiice and means under the control of an operator at the central ofiice for selecting an outgoing channel and rendering the reperforator-transmitter operative to relay messages from a branch office over the selected channel.

A still further object of the invention is to pro vide a printing telegraph exchange system having a main or central oiiice, one or more branch oiiices, selective switching means at the central oi'fice for automatically relaying message groups of signals from the branch ofiices to outgoing channels terminating at the central ofiice and double or multiple storage means for storing the signals, such as storing devices associated with incoming channels and other storing devices associated with outgoing channels from the central office. Such a system simplifies the interconnection of start-stop printing apparatus with multiplex channels and permits the operation of the several apparatus units at difierent speeds, if desired.

A still further object of the invention is to provide a telegraph exchange system having improved means for interconnecting incoming and outgoing lines or channels and for rendering the transmitting apparatus associated with a pluralityof incoming lines operative in sequence when the lines are extended to the same outgoing channel.

Another object of the invention is to provide in a telegraph system means for storing and repeating signals to control the operation o1? a remote printer or other receiving apparatus and ceipt of a predetermined signal by the printer or other receiving apparatus.

' Another object of the invention is to provide a telegraph exchange system having means for transmitting signals over a selected line or channel, means for automatically stopping the transmission of signals in case the transmitting circuit becomes opened or grounded and/or means for operating a signal when the transmitting circuit is open or grounded.

Other objects and advantages of the invention will become apparent from the following description of a preferred embodiment thereof shown on the accompanying drawings wherein Fig. 1 is a'diagrammatic view of the general arrangement of circuits and apparatus at a main or central oiiice connected to three branch ofilces;

Fig. 2 is a front elevationalview of a portion of the switchbard with associated receiving and transmitting apparatus at the main oflice;

Fig. 3 is a circuit diagram of the reperforatortransmitter and associated circuits individual to each of the incoming lines from branch oflices;

Figs. 4, 5 and 6 are circuit diagrams ofthe apparatus associated with outgoing lines or channels and with other units such as spillover reperforators accessible through the switchboard at the main oflice; and

Fig. 7 is a diagram illustrating a modification wherein triple storage is employedl Referring to Fig. 1 of the drawings, a typical system shown by way of example comprises a plurality of branch or subscribers ofilces BOI, B02 and B03 connected to the main or central oflice by lines Ill. II and i2, respectively. Other lines l3 and I4 extending to remote ofices terminate in a multiplex distributor MD and a terminal duplex set TDS, respectively.

In accordance with one feature ofthe invention, message groups of signals in printing telegraph code originating in a branch or remote office are stored in the central oflice, and, under the control of an attendant at the central oilice,

are relayed or retransmitted over a selected one of the outgoing circuits. Since certain of the transmitters or printers may be of the startstop type and in other elements of the system synchronism may be maintained by other means than the use of start-stop signals, the invention provides for the interconnection of both types of apparatus and for the operation of the various units at different speeds in order to obtain maximum efliciency.

In the embodiment of the invention shown, the start-stop transmitters TRI, TR2 and TR3 at the branch or subscribers oflices are connected to signal storage devices, such as reperforators RRI, RR2 andRR3 at the central oilice adapted to record the messages on tape in a form adapted to operate a tape transmitter. If desired, other types of storage devices may be utilized such as metallic or electrical storage devices arranged to store a suitable number of code signals to be subsequently repeated. A storage device of the socalled infinite storage type providing a perm'anent record of both message signals and printed characters is preferred however. Each reperforator has associated therewith a tape transmitter 'I'I'l, 'I'IZ, TT3 for repeating the stored signals, each transmitter being connected to switching means controlled at the central office for relaying the message over a selected line or channel terminating at said oflice.

In its preferred form, the switching means at the central omce comprises a switchboard of the conventional plug and jack type and constructed as shown in detail in Fig. 2. The plugs l5 are connected to cord circuits individual to the respective transmitters and the multipled jacks ii are connected to circuits 20, 2|, 22, 23 and 24 to outgoing lines or channels, or circuit 25 to reperforator RR4 for storing deferred or spillover messages, or circuit 28 to a printer RP4 at the local receiving position. A transmitter TR4, for example, a keyboard tape perforator and tape transmitter, is also provided at the local position in the central oflice for sending messages originating at said office. The transmitter TR4 by means of its associated cord circuit and connecting plug l5 may be connected to any of the circuits terminating in the jacks I6. Messages recorded by the spillover reperforators RR4 may be repeated by the associated tape transmitter TT4 through the switchboard into any one of the outgoing lines. Similarly, messages received over the lines l3 and I4 and recorded by the reperforators RR5 and RR6 may be relayed through the cord circuits individual to the associated tape transmitters 'I'I5 and TTS, respectively.

Each of the cord circuits is provided with control relays 30 adapted to render the associated transmitter operative under certain conditions, as will be explained hereinafter in connection with the detailed description of the circuits shown in Figs. 3, 4, 5 and 6; to stop the transmitter at the end of each message; and in connection with a circuit allotter CA to send messages in sequence in case more than one transmitter is plugged into the same outgoing channel or switchboard circuit at the same time. The circuit 20 from the switchboard to the line it includes a reperforator RR! having associated therewith a tape transmitter 'ITI connected to one channel of themultiplex distributor MD. The circuit 20 further includes control relays 33 arranged in connection with a numbering device 34 to interpose service signals such as consecutive numbers between message groups of signals. The circuit 2| from the switchboard to the duplex signaling circuit l4 includes control relays 35 and a monitor printer MPR for recording the messages transmitted in printed form. A numbering device 36 similar to the device 34 may be provided if desired in connection with the signaling circuit 14 or any of the other outgoing lines or channels. The circuits 22, 23 and 24 from the switchboard to the branch oiiice lines I0, II and I2 are provided with control relays 31 arranged to start the central oflice transmitter upon the depression of a push button 38 by the branch ofiice operator who is signalled by the calling lamp or signal 39 when a message is to be transmitted from the central oflice to the branch ofllce. The circuits 25 and 26 from the switchboard to the spillover reperforator RR4 and printer RP4 are provided with control relays 40 and 4| operating in conjunction with the cord circuit relays 30 to close the signaling circuits and start the connected transmitters at the beginning of a message and to open the signaling circuits at the I end of each message.

Each group of message signals is followed by an end-oI-message signal which stops the tape transmitter in the cord circuit and releases the outgoing channel or line so that another message waiting for said channel or line may be sent immediately. An operator or attendant at the central omce simply plugs each transmitter into the proper channel after noting the destination of a message from the printed tape. The message is sent automatically as soon as the selected channel becomes available and no further attention is required of the operator except to withdraw the plug upon receiving a signal that transmission has been completed.

In addition to the advantages accruing from the supervision and routing of messages in the central oflice, the system embodying the invention possesses material advantages over full automatic switching of telegraph circuits wherein the selection of lines or channels is controlled from the originating office'., Special services may be provided, such as timed wire service, sending full rate messages ahead of. deferred messages which are held in the spillover position, etc. The numbering of consecutive messages over heavily loaded channels greatly facilitates the tracing of lost or mutilated messages. Furthermore, since the messages are stored and repeated in the process of switching the circuits, each stage of the transmission may be carried out at the highest practicable speed and no difficulty is encountered in working start-stop transmitters into the synchronous distributors of multiplex systems. This is advantageous because of the fact that many branch oifices are equipped with start-stop transmitters and the heavily loaded inter-city trunks are usually operated multiplex. It will be apparent that various types of control or switching apparatus may be employed at the central oifice for interconnecting lines and relaying groups of signals and that otherjmodifications in the system shown schematically in Fig. 1 and in detail in Figs. 3, 4, 5 and 6 may be made without departing from the scope of the invention. It is believed, however, that the specific types of apparatus units and their relationship as illustrated in the drawiings have certain advantages for use in multi-ofiice printing telegraph systems of the usual character.

Fig. 2 illustrates a preferred arrangement of the switchboard and associated storing and retransmitting apparatus. The portion of the switchboard illustrated includes two vertical spaced panels 50 and 5| containing multipled jacks l6. Suitable labels 52 are arranged adjacent the respective jacks in each panel and calling and supervisory lamps 53 are mounted at the upper ends of the switchboard panels. printers, reperforatorsand tape transmitters associated with the cord and jack circuits of the switchboard are mounted in tiers adjacent the respective panels, as shown. The panel 50 is associated with the inter-oflice duplex trunk ll. The receiving reperforator RRG and tape transmitter TIB associated with the receiving side of said trunk and the monitor printer MPR for supervising transmission into said trunk are mounted adjacent said panel 50. The cords connecting the respective transmitters to the plugs 15 are indicated by the dotted lines 54. The panel 5| is associated with the multiplex inter-ofllce trunk l3 and the receiving reperforators RR5 and R and tape transmitters 1T5 and 'I'I5', and the sending reperforators RBI and RBI and tape transmitters 'ITI and TT'I' associated with two channels of said trunk are mounted adjacent said panel. The-switchboard panel associated with branch oflice lines II), II and I2 may be similarly arranged except that, since no storage or monitoring of the'code s'i'gnalstransmitted over said lines from the central ofllce is required, the three receiving units consisting of repertorators RRI, BB2 and RR3 and tape The.

'tion to the switchboard panels maybe varied depending upon the character and number of ap-. paratus units required, the traflic conditions encountered and other considerations.

Detailed description The system shown diagrammatically in Fig. l is illustrated in detail in Figs. 3, 4, 5 and 6. Fig. 3 is a circuit diagram of two cord circuits for extending calls from two tape transmitters I'Il and TT2 to switchboard jacks IS in the same or separate panels or sections of the switchboard. As shown in Fig. 1, each incoming line whether from a local branch ofiice or remote omce terminates in a receiving-storing device and transmitter, such as a tape printer and reperforator,

and tape transmitter. In each case a cord cirsuit individual to each tape transmitter is provided and thus the tape transmitter and cord circuit shown in the upper half of Fig. 3 is illustrative of each of the receiving and retransmitting units on incoming lines at the central oflice. The transmitters and cord circuits at the spillover position and at the local sending position (Fig. l.) are also similar to those shown in Fig. 3.

The branch oflice, printers may be provided with start-stop simplex transmitters TRI, TR2 and 'I'R3 similar to the Tape Teletype (Model 14) described in Bulletin No. 126 of the Morkrum- Kleinschmidt Corporation. The receiving reperforators Rltl, BB2 etc., preferably print the message character as well as perforate a tape in such manner that when said tape is passed through a tape transmitter, the message signals will be repeated, and may be of. the type shown in the patent to Rothermel, No. 1,936,956, dated November 28, 1933, or that shown in the copending application of Robert F. Dirkes and Evan R. Wheeler, Ser. No. 42,692, filed September 28, 1935. The tape transmitters associated with each cord circuit may be of the type shown in the patent to Rothermel, No. 1,805,374 dated May 12, 1931'.

The described system may utilize simplex, duplex or multiplex transmission channels of various types and the transmitting and storing wherein continuous synchronism is maintained between the two terminal stations or wherein start-stop impulses at the beginning and end of each signal are utilized to maintain synchrois not limited in respect to' the type of circuits or apparatus employed or to uniform transmission rates in difierent parts of the system as in the case of telegraph exchange systems heretofore proposed. a

Transmission from branch office to second branch ofi'ice As shown in Fig. 3, the line l0 extending to a branchv office where it is normally grounded is connected through a switch 60 to the operating magnet 6| of reperiorator RBI and to thewinding of a normally energized relay 62 having the or recording apparatus may be either of the type other terminal thereof connected tobattery. The first spacing signal received over the line 10 from the transmitter TRI causes the relay 62 to become deenergized, thereby closing the circuit of the calling lamp 63 through the right hand armature and back contact of said relay. The winding of relay 62 is short-circuited through its left. hand armature and back contact and the signal lamp 53 remains lighted until the switch 84 is opened after completion of transmission of the message. The message is recorded in the form of a perforated tape by the reperforator RBI and preferably also printed upon the same or another tape as in the apparatus described in the patent to Rothermel, No. 1,936,956, and the copending application of Dirkes and Wheeler referred to above. In the case of messages received over a duplexed or multiplex line, the messages are recorded and a lamp or other signal operated in a similar manner. The messages are thus cleared out of the originating ofllce without delay because of busy channels at the central office or other causes.

The tape transmitter TI! is associated with the reperforator RRI and is connected to the switchboard through a cord circuit 65 individual to the line In and terminating in the plug ii. The line H is provided witha similar reperforator RR! andtape transmitter TH, and messages received over said line are relayed through a second cord circuit ii individual to said transmitter and line to an outgoing line or switchboard circuit accessiible from the jacks I8. The cord circuits individual to the respective incoming lines are all identical and therefore the detailed description of the cord circuit individual to line l (Fig. 3) will suflice.

Upon receiving a message upon the reperforator RRI, the operator notes the destination of the message from the tape and plugs the cord circuit 65 into the jack l6 corresponding to the proper outgoing line or channel. Assuming that this is the line I! to branch oflice B03, (Fig. 4)

type of receiving equipment. Each Jack I coma,

prises tip and sleeve contacts adapted to receive the tip and sleeve of the plug II. The tip circuit is employed to transmit the code signals from the tape transmitter associated with the cord circuit to the receiving apparatus and the closing of the sleeve circuit causes the transmitter to seize the outgoing line or channel if it is idle and renders typical circuits have been illustrated in Figs. 4, 5 and 6.

When the switchboard plug i5 is raised for insertion into a switchboard jack, the plug seats switch '12 is closed thereby closing a circuit through switch 13 and left hand inner armature and back contact of relay H for lighting the supervisory lamp II. The plug seat switch 12 closes a second circuit through the winding of slow release relay l6 and the right hand inner armature and back contact of relay I! to energize relay 16. The energization of relay 16 opens the circuit through the start magnet SM of transmitter 'ITI to guard against premature starting of the transmitter.

Assuming as stated above that the connection is to be extended to a start-stop printer at branch office B03 and the plug I5 is inserted into Jack Ii connected to conductors i and :i, a circuit is closed through the winding of relay 18 (Fig. 4), conductors II and i, sleeve of jack l6, sleeve of plug l5, right hand winding of test relay ll, resistance II, and the right hand armature and back contact of relay H to the brush "of circuit allotter CA. The circuit allotter CA comprises a plurality of spaced brushes, one for each cord circuit, and a rotating grounded segment 82 arranged to connect each of said brushes momentarily and successively to ground. If the line to branch ofilce B03 is idle, relays II andbe come energized, when segment 82 engagesthe brush 8|. If the line has been seized by a second cord circuit, the multipled jacks individual to said line will be busy" as described below and test relay II will not be operated until the connection has been released. I

If the selected line is idle, the energization of test relay 1! closes a circuit from positive battery through the winding of relay Ii, conductors II and 1', sleeve; of jack I! and plug ll, windings of relays 83 and 84, left hand armature and front contact of relay 1!, left hand winding of relay 1!, right hand armature and back contact of slow release relay .5, left hand outer armature and back contact of relay 1'! and the armature and back-contact of relay I to negative battery, thereby energizing relays l3 and II. The energization of relays 83 and 84 places a ground on the described circuit between the windings of relays N and I through a circuit including the armature and front contact of relay II and the left hand armature and front contact of slow release relay 84. Thus the relay II and 83 are locked up as long as relay '4 is operated and the potential of sleeve of Jack I is such that the test relay of another cord circuit will not operate when connected thereto as the resistance of the test relay circuit is large compared to that of relay .3.

The energization of relay IO reverses the potential of the line I! extending to the branch ofilce B03 through a circuit leading from the inner armature of said relay through the winding of marginal relay l1, outer armature and back contact of relay II, line It, operating magnet II and the normally closed rest contact of the transmitting contacts ll of the receiving printer RPS, winding of the polarized relay II and resistance I! to ground. The polarized relay II responds to the change of polarity of the line and closes the circuits of the calling lamp 3! and buzzer I to notify the operator at the branch oiilce that the main office desires to transmit a message. The marginalrelay "does not operate on normal line current and therefore does not close its contacts until the line current isincreased as described below.

The attendant at branch office B03 may initiate transmission of the message, after starting the printer motor or completing any other preliminary operations, by momentarily closing switch 38. The contacts of switch 38 are arranged to short-circuit the resistance 92 where through its armature and back contact and the, outer armatures and front contacts of relays 94 and 18 for energizing .relay 88. The outer arma-' ture of relay 88 is connected to the line I2 and the energization of said. relay transfers the line from the contacts of relay 'I8 to the tip conductor II which is connected through the tip contacts of the switchboard plug and jack, the right hand armature and front contact of relay 84, the winding of relay 95; the winding of marginal relay 86, the normally closed rest contact of thetransmitting contacts 96 of transmitter 'I'II and resistance 91 to negative battery.- The transmitter TTI is now connected to the line wire in readiness to start transmission.

Since the line I2 is now connected to negative battery at transmitter "I'Il, the armature of the polarized relay 9| is actuated to open its contacts, thereby extinguishing signal lamp 39 and opening the circuit of-the buzzer 93 at the branch oflice B03. Relay 95 is energized but marginal relay 86'is adjusted so that it will not operate on normal linecurrent. It will operate, however, if the line current is increased by the closure of switch 38 or contact I08 in the printer RP3 in response to the transmission of the endof-message signal as described below; it will also operate if the line between the main ofiice and the branch office becomes grounded. Relay 86 is arranged to stop the transmitter TTI, as will be described hereinafter, and thus this operation may be effected manually by the attendant at branch oflice B03 or automatically in response to the transmission of the end-of-message signal orthe occurrence of a ground on the line circuit.

Upon the energization of relay 95, a circuit is closed from battery through the winding of slow release relay 85, the armature andfront contact of relay 95 and the winding of relay 98 to ground, whereupon relays and 98 become energized. Relay 98 closes a locking circuit for itself and relay 85 that is independent of relay 95. Upon the energization of relay 85,'a circuit is closed through its left handarmature and front contact for energizing relay' I4, and at its right hand armature and back'contact relay 85 opens a.

short-circuit around the winding of relay 'II whereupon relays I4 and 1'! become energized. The energization of relay "opens the circuit of signal lamp I5 at its left hand inner armature, extinguishing said lamp to indicate to the attendant that transmission" of the message has started, and closes through said armature a looking circuit for said relay through switches 12 and 13. right hand winding of test relay 19 to the circuit allotter CA and closes a circuit from the latter to the winding of relay 88 whereby the winding of under normal conditions.

The relay 14 also opens the circuit from the the said relay is periodically short-circuited. The purpose of this arrangement is to guard against transmission into. an open line between the central oflice and they branch or remote oflice as will be explained below. i

The energization of relay H, as above described, opens at its inner right hand armature and back contact the circuit of slow release relay 16 whereupon this relay becomes de-energized and closes the circuit of the start magnet SM of the tape transmitter TTI. The delay in closing the start circuit of transmitter TTI permits the printer RP3 to come to rest if the cam shaft of the printer was released upon the reversal of the polarity of the line I2 by the operation of relay 88. The circuit of the start magnet SM includes the armature and back contact of relay I6 and the left hand inner armature and front contact of relay I1. Upon the energization of the start magnet SM, the transmitter TTI starts to transmit the signals stored in the tape from the reperforator RRI over the line I2 to the printer RP3 at branch oflice B03.

If the line I2 should become opened or grounded after transmission has started, it is desirable that transmission be stopped automatically to prevent loss of signals. To this end the operation of the transmitter 'I'II is controlled in accordance with the condition of the line in a simple and effective manner and without interrupting transmission Relay is connected in series with the line so as to be traversed by the signaling currents. Therefore, each time the signaling circuit is interrupted, relay 95 becomes dc-energized. As pointed out above, relay 98 is periodically de-energized by the circuit allotter CA which periodically closes a shortcircuit around the winding of relay 98 through the right hand armature and front contact of relay The circuit allotter is preferably con-' structed to effect this result everytwo or three seconds or at even shorter intervals. Since the ground connection through the circuit allotter CA is of low resistance, relay 98 becomes de-energized every time the brush 8| contacts with the segment 82. If relay 98 is de-energized at the same time that relay 95 is de-energized, the circuit of relay 85 will be opened. Relay 85 is a slow release relay and its armatures will not be released immediately. If the line I2 to the branch offlce B03 is in operable condition and is not open, a marking signal willbe transmitted over said line with a minimum frequency of once in each character transmitted, thereby reenergizing relay 95 and reclosingthe circuit of relay 85,within a; definite time limit. The slow release relay 85 is adjusted so that it will not release during such time limit and therefore when the line is in operable condition, relay" 95 will reclose the circuit of relay 85 through the armature and winding of relay 98'beforerelay 85 opens its conengagement of segment 82 with the contact 8I of the circuit allotter CA, relay 9 will become deenergized. The'deenergization of relay98 will open the circuit of relay 85 and since the line circuit is open, relay 95 remains deenergized so that relay 98 cannot be reenergized and the circuit of slow release relay 85 remains open. After a short interval of time relay 85 becomes deenergized and closes at its right hand armature and back contact a short-circuit around the left hand winding of relay 19. This circuit may be traced from said winding to the right hand armature and back contact of relay 85, and through the left hand outer armature and front contact of relay 1! to the other terminal of the left hand winding of relay l9. Thereupon relay 19 becomes deenergized and opens the circuits of relays I1 and 84. When relay 1'! becomes deenergized, the circuit of the start magnet SM of transmitter TTI is opened at the left hand inner armature and front contact of said relay whereupon the transmitter 'I'Il stops. The deenergization of relay ll also closes a circuit through its right hand inner armature and back contact,

the winding of slow release relay l8 and the contacts of plug seat switch 72? to ground, whereupon relay it becomes energized and opens at a second point the circuit of the start magnet SM of transmitter I'Ti.

The deenergization of relay ll further closes a circuit through the right hand outer armature and back contact of said relay and the left hand outer armature and front contact of relay i l for lighting signal lamp 99, indicating that transmission has stopped. Relay l'l further closes a short-circuit around its own winding through its left hand outer armature and back contact, and the right hand armature *and back contact of relay 85. After the deenergization of relay l'l, slow release relay becomes deenergized, thereby opening at its right hand armature and front contact the circuit'from the transmitting contacts 98 of the transmitter TI! to the printer RP3 at the branch ofiice B03. The deenergization of relay 8 3 also opens the circuit of relays 33 and 78 whereupon said relays become deenergized. All of the relays associated with the cord circuit 85 are now deenergized except relays i i and it. Relay T l may be deenergized by the attendant at the central ofiice by operating switch 73 or both relays 7-! and it may be deenergized by removing plug i5 from the jack and returning said plug to its seat, thereby opening the plug seat switch '12 and removing the ground connection from the circuits of the windings of relays M and it. The attendant at the central office will note that the message passing through the transmitter TTI has not been completely transmitted and will take the necessary precautions to avoid the loss of said message.

When the line between the central oflice and the branch office is accidentally grounded during the transmission of a message, transmitter T'I'l will be stopped in the following manner:The ground upon the line circuit will cause the line current to be increased and thereby operate marginal relay 8G. The operation of relay 8G. will open the battery supply through its armature and back contact for the windings of relays Ti, 19 and 8d, whereupon relays I1 and 19 are deenergized and slow release relay 84 will be deenergized a moment later. The deenergization of relay 1! opens at its left hand inner armature and front contact the circuit of the start magnet SM of the transmitter TT! and the transmitter stops. Relay ll also closes through its right hand inner armature and back contact the circuit of relay l6 and this relay becomes energized. At its right hand outer armature and back contact, relay l1 closes the circuit of signal lamp 99 and this lamp is lighted to indicate to the attendant that transmission has ceased.

When relay 34 becomes deenergized, it opens areaen the circluit of the transmitter IT! at the right hand armature and front contact of said relay. The deenergization of relay 84 further opens at its left hand armature and front contact the circuit of relays 83 and 18 whereupon said relays are deenergized. Relays and 86 are deenergized when the circuit through the right hand armature and front contact of relay 84 is opened.

Upon the next engagement of brush 8| and segment 82 of the circuit allotter CA, the winding of relay 98 is short-circuited whereupon said relay becomes deenergized and opens the circuit of relay 85. Upon the deenergization of relay 85 a short-circuit is completed around the winding of relay '11 through the right hand armature and back contact of relay 85, and the left hand outer armature and back contact of reltay 71. All of the relays in the cord circuit 65 are now deenergized except relays M and 1B. Relay l l may be deenergized by the attendant at the central ofiice by opening switch 13 in the locking circuit of said relay or both relays it and it may be deenergized by returning the plug it: to its seat, thereby opening the plug seat switch 72 and removing the ground connection from the windings of relays ill and it. The attendant at the central office will note that the message in the transmitter 'I'Il has not been completely transmitted and will take the necessary steps to insure against the loss of said message.

At the end of each message an end-of-message signal originally appended to the message by the operator at branch office is transmitted by the transmitter, as for example, a bell signal which operates upon a code signal corresponding to the upper case J. When this end-of-message signal is received in the printer RPS (Fig. 4) the operation of the printer in response to said signal will cause contacts Hill of the printer to close momentarily thereby providing a shortcircuit path to ground around the resistance 92. In this manner the line current in the circuit is momentarily increased and marginal relay 86 becomes energized. The energization of relay 86 opens the battery circuit of relays ll, 79 and 8:3, whereupon relays l1 and F9 are immediately deenergized and slow release relay 8t becomes deenergized a moment later.

When relay 7? is deenergized, the circuit of the start magnet of said transmitter TTI is opened and the transmitter stops even though there may be another message awaiting transmission in the tape. The deenergization of relay l7 closes a circuit through its right hand inner armature and back contact for energizing relay l6 and upon the operation of relay 16, the circuit of start magnet SM of transmitter TT! is opened at a second point. The deenergization of relay 7! further closes through its right hand outer armature and back contact the circuit of signal lamp 99, whereupon this lamp is lighted to indicate that transmission has ceased.

Upon the deenergization of relay 8 3 the circuit of the transmitting contacts 96 of the transmitter TTI' is opened at the right hand armature and front contact of said relay. The deenergization of relay 84 further opens at its left hand armature and front contact the circuit of relays 83 and I8 whereupon relays 83 and it become deenergized. The circuit of relays 86 and 95 is 85 and 98 in shunt to the contacts of relays 98 75 whereupon these relays become deenergized as soon as the grounded segment 82 of the circuit allotter CA effects the short-circuiting of relay 98. Upon the deenergizatlon of relay 85 the circuit of relay 14 is opened but this relay remains energized through its locking circuit including switches I2 and 13. Thus it will be seen that as a result of the -end-of-message signal, transmitter TTI has been stopped, the line from said transmitter to the branch omce has been opened at the contacts of the relay 94, the signal lamp 99 lighted, and all the cord circuit relays except relays I4 and 16 have been deenergized. The circuit allotter CA will now function to cause any other cord circuit which may be waitingfor a connection to the branch office B03 to be connected to said station through the line II in the manner already described. The transmitter 'I'II will not be reconnected to the line I2, however,

because relay I4 remains energized and thus holds open the circuit of the test relay 19 which initiates the operation of the control apparatus. Therefore, although the plug l5 may be allowed to remain for an indefinite time in the jack I6, the connection so established will have no effect and messages that may be awaiting transmission at other positions for branch office B03 will be sent.

The signal lamp 99 is lighted, however, to notify the central ofiice attendant that transmission of the message has been completed and the trans- ,mission circuit released. If there is ,another message awaiting transmission on the tape from v the reperforator RRI, this message may be destined either for the same branch ofiice B03 or for another branch or remote ofiice. If there is no other message on the tape from the reperforator RRI the. attendant in response to the lighting of lamp 99 removes the plug.l5 from the jack and restores it to its seat. The contacts of the plug seat switch I2 are opened, thereby opening the circuits of relays I4 and I6 whereupon th'ese relays become deenergized and the lamp 99 is extinguished. The cord circuit and associated apparatus are now restored to normal.

If there is another message on the tape destined for branch ofiice B03, it is unnecessary to withdraw the plug from the jack. The operator merely actuates the 'switch.I3 to open momentarily the locking circuit of relay I4 whereupon this relay becomes deenergized and the lamp 99 is extinguished. The deenergization of relay ll closes through its innerleft hand armature and back contact the circuit of lamp I5, and through its right hand armature and back contact connects the test relay I9 to the circuit allotter CA. Relay I6 remains energized and prevents a premature closure of the circuit of the start magnet SM of the transmitter TTI. The connection of the transmitter to the line to the branch oflice B03 as soon as the line is idle takes place in the manner described above.

If there is a message on the tape destined for another outgoing channel or circuit allotted to a jack IS in the switchboard, theplug I5 is withdrawn and restored to its seat, thereby opening the, contacts of plug seat switch" I2 and deenergizing relays I4 and 16. The plug is then inserted in the jack connected to the desired channel or circuit and transmission of the message follows in the .usual manner.

In the foregoing description it was assumed that the selected line, i. e-.'the line I2 to branch office B03, was idle when the transmitter T1! was connected theretoby the associated plug l5 and cord circuit 65. If the line is busy because of a prior connection" to another transmitter and cord circuit, the transmitter TTI is held inoperative until the transmission of the first message is completed and the line is released. If more than two transmitters are connected through their cord circuits to the same line or circuit, the circuit allotter CA renders the transmitters operative one after the other without attention from the operator or attendant.

If the line I2 has already been seized by another transmitter before the transmitter'TTI is plugged into the switchboard, the conductor a of the switchboard multiple is connected to ground through the sleeve of the plug l5 of the other transmitter, the winding of the relay correspondj ing to relay 83 and the contacts of relays corresponding to relays 83 and of the cord circuit 65. The test relay I9 therefore does not operate when ground is applied to the right hand winding thereof by the circuit allotterCA and to transmit over said line'as described above upon the first engagement of segment 82 of the circult allotter with brush 8|.

Interojfice transmission with numbering of suncessive messages As shown, the system embodying the invention provides means for inter-posing service code signals such as consecutive numbers betweensuccessive messages in connection with transmission to remote oflices over duplex circuits or multiplex channels. The service code or numbering mechanism may also be employed in connection with the local branch omce lines, if desired, but ordinarily is not required because of the small volume of traffic to such oilices.

The switchboard circuit leading to the terminal duplex set T138 and line I 4 is shown in the lower half of Fig. 4, the service code signal transmitter or. numbering mechanism 39 individual to 'saidline being shown diagrammatically in Fig. 5.

messages, or other desired characters which may be different for consecutive messages. In this manner themessage as receivedincludes arbitrary characters for the purpose of facilitating the tracing. of lost or mutilated messages or for other purposes. The code signal transmitter shown in Fig. 5 is of the motor-driven cam switch type described and claimed in the copending application of Dirkes, Hoover andWheeler, Ser. No. 51,522, filed November 25,, 1935, but may be of any suitable type, for .example, one in which the code signals are stored in a perforated tape or other storage medium.

In the embodiment of the invention illustrated,

when a messag'etransmitter is connected to the trunk I d or a channel of the multiplex circuit I3, the associated numbering mechanism automatically transmits code signals of identifying character over the trunk or channel and thereafter the connected transmitter. is rendered operative to transmit the message stored in the associated reperforator. The trunk or channel is released by an end-of-message signal and the next message over the same channel is preceded by a different code signal group set up in the numbering mechanism so that each message as received includes distinctive identifying characters or numbers. Secondary storage of signals is preferably utilized in connection with transmission over multiplex channels in order to simplify the switchboard circuits and provide for varying rates of transmission in different parts of the system as required for maximum efficiency in the operation of both exchange apparatus and transmission circuits.

Assuming that a message is to be relayed from branch oihce BOI to a remote ofi'ice connected to the duplex line I4, the message is initially printed and stored at the central oflice by the combined printer and reperforator RRI (Figs. 1 and 3) as described above. After noting the destination of the message on the tape, the attendant at the central office plugs the cord circuit associated with the tape transmitter 'I'I'I into the jack I 5 allotted to the outgoing line H, thereby extending the connection to the conductors k and Z of the switchboard multiple and the conductors i ii) and III (Fig. 4). It is assumed that the monitor printer MPR and the receiving printer at the remote terminal of the duplex line I i are of the start-stop type and accordingly may be connected directly to the transmitter TTI.

When the plug I5 is inserted in the jack 15, the plug seat switch 12 is closed, thereby lighting the signal lamp 15 and energizing relay 16. If a connection is not already established with the line I d, the test relay 19 becomes energized through a circuit including the brush 8! and the grounded segment 82 of the circuit allotter CA, the right hand armature and back contact of relay 15, resistance 80, the right hand winding of relay 19, the sleeve contacts of plug I5 and jack I6, con ductors I and Hi, switch .H2 and winding of relay H3 to battery, whereupon relays 19 and I I3 are energized. If the line It is busy, the sleeve of the jack IE will be at a potential indicating busy condition as described above and the op- .eration of test relay 19 to initiate the operation of transmitter TTI will be prevented until the line HI becomes idle.

Upon the energization of relay 19, relays 83 r and 84 become energized through a circuit including the armature and back contact of relay 86, left hand outer armature and back contact of relay 17, right hand armature and back contact of relay 85, left hand winding and armature of relay' 19, windings of relays 84 and 83, sleeve contacts of plug I5 and jack I6, conductors I and Hi, and winding of relay H3. The switch H2 in series relation with relay H3 is provided for the purpose of rendering the channel It or the multiple jack circuit equipment associated with terminal duplex set 'I'DS busy if it is desired to prevent any cord circuit from seizing said channel. If the switch H2 is open, the operation of test relay 19 is prevented and the transmitter associated with a cord circuit plugged into the channel It will be maintained inoperative. Relay H3, however, is provided with a. locking circuit through its left hand armature and front contact so that after the channel has been seized and relay H3 energized, the circuit is not affected by the opening of switch H2 until transmission of the message has been completed and relay H3 is deenergized.

The operation of relay 84 connects the tip circuit of the switchboard multiple through its right hand armature and front contact and the windings of relays and 86 to the transmitting contacts 96 of transmitter TTI. The transmitting circuit is interrupted, however, at the right hand armature and front contact of relay H4 as this relay remains deenergized until the numbering mechanism 35 has completed its function. The energization of relay H3 closes a circult from ground through its right hand armature and front contact, the left hand armature and back contact of relay H4 and conductor lit for energizing the clutch magnet II1 of the numbering or service code signal transmitter 36 (Fig. 5), thereby initiating the rotation of the transmitting cam drums of the transmitter.

In the embodiment shown, the numbering mechanism 35 comprises a constantly rotating drive shaft I25 connected through a clutch I26 to the normally stationary cam drum I21. When the clutch magnet H1 is energized, the clutch I25 is engaged and the drum I21 rotates with the drive shaft I25. The clutch I25 is provided with a cam I28 and stop arm lever I29 to disengage the clutch and stop the cam drum I2! in a predetermined start position after the clutch magnet M1 is deenergized. The numbering mechanism further comprises 2. letters code drum I30, a units code drum IN and a tens code drum each of said drums being intermittently stepped during the rotation of the transmitting cam drum I21. As shown, a Geneva cam I33 and Geneva wheel I34 are disposed between each pair of drums in such manner that the letters code drum I38 is stepped'once for each revolution of drum I21, the units code drum I3I is stepped once for each revolution of drum I31] and the tens code drum I32 is stepped once for each revolution of drum I3I.

Each of the rotatable drums is provided with projecting pins or cam members I35 adapted to engage movable contact members I36 having cooperating front and/or back contacts. The

operation of the contact members I36 in properly timed relation and in predetermined sequence by the drums I21, I39, I3I and I32 is arranged to send marking and spacing signals to a storage reperforator or the remote printer to print suitable characters which are appended to the message for the purpose mentioned above. The code signals sent automatically during each cycle of operation of the numbering mechanism 36 may be readily changed by properly rearranging the pins I35.

The mechanism 35 further comprises a relay I40 and a restoring switch III, the latter being used for restoring the units code drum I3! to a predetermined starting position when desired. The tens cam drum I32 is preferably also arranged to permit resetting manually when desired, as for example, by disengaging the Geneva wheel I34 of said drum from the cooperating cam I33, thus permitting the drum to be turned to its starting position as described in the above mentioned copending application of Dirkes, Hoover and Wheeler.

Upon the energization of the clutch magnet H1, the transmitting cam drum I21 rotates and during each rotation, a character or code si nal is transmitted over the conductor I45. Ten

revolutions of the cam drum I21 c'onstitute one interval, five marking or spacing impulses and a stop or current pulse whereby the signals are adapted to control the ordinary start-stop printer. When battery is connected to the conductor I45, the operating magnet I46 of the monitor printer MPR at the central office and relay I41 of the terminal duplex set TDS are energized, the circuit of said magnet and relay including a resistance I48 which is short-circuited by the closing of contacts I49 of the monitor printer. The monitor printer MPR and relay I41 thus respond to the signals transmitted by the numbering mechanism 35.

As shown, the movable contact members I36 of the transmitting cam drum I21 are connected together and to the conductor I45. Battery is connected to theback contact I50 cooperating with the first or rest contact member I36 of drum I21. Upon the initial movement of drum I21 from its normal position, the circuit including contact I50 is opened thus opening the line during the start interval. This circuit remains open until the drum I21 returns to its initial position. After five successive impulses are sent to the line by the successive operation of the remaining'contact members I36 of drum I21, the drum completes one revolution and recloses the line circuit through contact I50 to send the stop pulse. The code signal sent during each revolution of drum I21 is controlled by con-.

necting or removing battery potential from the make contacts corresponding to the second, third, fourth, fifth and sixth contact members I36 of drum I21 in accordance with the setting of code drums I30, I3I and I32. The ten revolutions of drum I21 during each cycle cause drum I30 to make one complete revolution and drum I3I to make one-tenth of a revolutionduring each cycle of the numbering mechanism whereas the tens code drum I32 is stepped once in ten cycles.

The first five contact members I36 of drum I30 are connected to the make contacts of drum I21 and when actuated are connected to battery through the back contact I5I of the sixth con tact I36 of drum I30. In the normal or first position of the code drum I30,.the code pins 135 engaging the cooperating contact members I36 of drum I30 connected to the make contacts of drum- I21 may be arranged in accordance with the code signal representing the letters shift. Upon the first rotation of the cam drum I21, a letters shift signal will be sent to the lineto adjust the printer MPR and the printer at the remote oflice to print letter characters. During the transmission of the stop and start pulses by contact I50, the letters code drum I30 is stepped to its second position wherein the code representing a character identifying the channel I4,

for example is set up on the pins." This character may be the letter F where the characters FWA are employed to designate the line I4 to a remote .ofilce. Upon the succeeding rotations of drum I21 the signals representing W, A

and the figures shift are sent to the line under the control of letters code drum I30.

In the sixth position of the letters code drum- I30, only the sixth and seventh contact members I36 of drum I30 are actuated by pins I36. The sixth contact member I36 connects battery to the make contacts of drums I3I and I32 through make contact I52 of drum I30. The

.IM and M5 (Fig.4).

seventh contact member I36 of drum I30 closes through its make contact I53 the circuit of transfer relay I40. The contact members I36 of transmitting cam drum I21 are thus connected through the back contacts of drum I30 and the armaof letters drum I30 opens the circuit including make contact I53 and winding of relay I40, whereupon relay I40 becomes deenergized and transfers the sending circuit from drum I32 to drum I3 I. In its initial position, units code drum I3I is arranged to send a signal representing the digit 1 and during the successive cycles of the numbering mechanism, drum I3I changes the code signal set up from i to 2, 3, etc. In this manner the numbering mechanism 36 interposes consecutive numbers from 01 to 99 or (1) between consecutive messages.

' In the eighth position of the letters cod-e drum I30, the sixth contact member I36 of said drum is restored to normal, thereby breaking the battery connection to the contacts of drums I3-I and I32 and connecting battery to the make contacts associated with the first five contact members I36 of drum I30. Thedrum I30 is then operative to send the letters shift signal to the line and, during the ninth and tenth revolutions of transmitting drum I21; to send blank or other desired signals. When the drum I30 is being stepped from its ninth position to its tenth position, the eighth contact member I36 of drum I30 applies ground potential momentarily to conductor I65, thereby energizing relays Relay H6 breaks the circuit of clutch magnet I I1 at the left hand armature and back contact of said relay. At this moment cam I26 has advanced so far that stop arm lever I26 does not immediately engage cam I20 and the transmitting drum I21 continues to rotatefor almost anotherrevolution. Then the cam I20 engages the stop arm lever I26 when thedrum I21 isin its rest position wherein contact I50 engages its associated contact. member I36, and drum I30 has been restored to its initial position. When the drum I30 comes to rest at its initial position, the described circuit of relays II4 and H is interrupted but the operation of relay H4 closed a locking circuit for said relays through its left hand armature and front contact and the right hand armature and front contact of relay II3 whereby relays H4 and H5 remainenergized until transmission of the message has been completed.

The terminal duplex set TDS is conventionally shown in Fig. 4' as comprising a differential line relay I60 having opposed windings connected to the line I4 and an artificial line I6I respectively. The armature of the transmitting relay I41 is connected to the mid-point of the windings of relay I60 so that the relay will transmitpositive and negative signaling impulses over the line I4 without affecting the line relay I60. Relay I60 will, however, respond 'to impulses received over the line I4 to control the receiving reperforator RR6.

' The energization of relay I as described above iii tudinally, slidable on nects through the same armature and front contact the monitor printer MFR and terminal duplex set TDS to the transmitting contacts 955 of the tape transmitter 'I'I'l. The transmitting circuit includes the windings of marginal relay 86 and relay 85. Relay 95 becomes energized, effects the energization orrelays 85, 8% I1 and 14, and initiates the transmission of the message stored by the reperforator RR! as described above in connection with the retransmission of messages to a local branch omce.

The numbering mechanism 35 remains inoperative until the line H3 is seized by one of the cord circuits for the transmission of another message. The second message will be numbered 02 because of the stepping of the units code drum H35 to its second position by the rotation of the drum L39; After nine cycles of operation, the rotation of the units code drum I3! steps the tens drum 132 so that the succeeding message will be numbered 10. In this manner the messages transmitted over the line l5 will be consecutively numbered. Obviously, any desired service code signals may be interposed between the messages and the signals may be produced in various ways by using other types of automatic code signaling devices.

It is deshable to be able to reset the tens and units code drums of the numbering device from time to time in order to number the first message 01 for example atthe beginning of each day. The units code drum ldl is reset by closing the switch Mi, thereby closing a circuit for energizing the clutch magnet Ml through the sixth contact member 536 and back contact i5 1 of drum as: if thisdlum is on any other position than number one. The drums 521, i353 and lti arerotated by the drive shaft. 525 until the drum I35 reaches its reset for #1 position where the circuit is interrupted at contact 555 through the operation of the associated contact member 236 bya code pin i215. The tens code drum 82 is preferably reset to normal position manually, the Geneva wheel 53d of said drum being long-lthe shaft of the drum to effect disengagement of the wheel from the cam 3233.

After the numbering mechanism has completed its function, the transmitter 'ITi is rendered operative as described above to send the message over the line H to the remote oilice. The endof-message signal causes the contacts "9 of the monitor printer MFR, to close momentarily, thereby short-circuiting the resistance 8 in the transmitting circuit to cause the operation of marginal relay 88. ithe cord circuit 65 is then restored to normal as described above. It will be noted that its. second cord circuit had seized the line I I before relays H3 and H! are deenersized, the transmitter in the second cord circuit 7 would be rendered operative immediately without waiting for the numbering mechanism 38 to function. This is prevented by slow release relay US which closes a shunt circuit around relays l l3 and 85 to ground through its armature and front contact. The resistance of this shunt circuit is so chosen that relays i i3 and 83 will remain operated once they are operated but that the test relay 79 of a second cord circuit will not be energized in Series with the winding of relay 3. The line ii is thus maintained busy for a short interval after relays I13 and H4 become deenergized to prevent a premature seizure of the line by the second cord circuit.

This delay in the connection of another cord When the monitor printer MFR is switched to the numbering mechanism 36, the circuit of the magnet M6 of the printer may be opened momentarily by the armature of relay H4 as it moves from its front to its back contact. This interruption of the circuit if of suiiicient duration will cause the printer to function as if 2. letters shift signal had been received. It is necessary that the printer complete its cycle and come to rest before thenumbering mechanism starts transmission in order to avoid the printing of false characters ahead of the characters transmitted by the num bering mechanism, and this is accomplished by the slow release relay i 35.

In the case of a message to be retransmitted over a multiplex channel, for example, of the line it, the cord circuit is connected through plug i5 and jack it to conductors m and n of the switchboard multiple, thereby extending the connection to the conductors Hi3 and ill leading to the control apparatus associated with the multiplex distributor MD (Fig. 6). If the selected channel is busy, the test relay ii) is not energized and the tape transmitter associated with the cord circuit is maintained inoperative as described above. If the channel is idle, a circuit is closed from battery through the winding of relay H2, switch H3 corresponding to switch H2 (Fig. 4), conductors W and n, sleeve contacts of jack E6 and plug 15, right hand winding of test relay is, resistance 88 and right hand armature and back contact of relay M to ground at the circuit allotter CA whereupon relays lid and W2 become energized. The energization of relay H2 closes a locking circuit through its left hand armature and front contact that is independent ofthe switch H3 and closes a circuit through its right hand armature and front contact and the right hand armature and back contact of relay. lid for energizing the clutch magnet 1 of the numbering mechanism The numbering mechanism 35 is similar in construction to the numbering mechanism but is arranged to send characters identifying the associated channel of line it). During the operaticn or the numbering mechanism 3 3, which is similar to that described above in connection with mechanism 36, the transmitting circuit of the tape transmitter 'ITl is held open at the left hand armature of relay I1 After the numbering mechanism 35- has completed its cycle, the contacts iltl are momentarily closed, thereby energizing relays I'll and I'M. Relay H 3 transfers the sending circuit from the numbering mechanism 3E to the transmitter 'ITE and slow release relay H1 is a guard relay corresponding to guard relay I 85 described above. Instead of transmitting the permutation code signals directly over the line, a reperforator RR! is provided for perforating a tape which may be fed into the tape transmitter 'I'Il having transmitting contacts Ill connected to the transmitting segments of the distributor MD and a tape stepping magnet I ll connected to the local segment of the distributor. The transmitter TI! and its connections to the multiplex distributor MD may be similar to those shown in the patent to Benjamin No. 1,298,440 dated March 25, 1919. It will be noted that the reperforator RR! is connected in a short intraofiice circuit over which signals may be transmitted if desired at a much higher rate than over the channels of the multiplex.

The reperforator RR] records the message preceded by the service code signals from numbering mechanism 34 on a tape and, upon receiving the end-of-message signal, closes the contacts I82 in the transmitting circuit to operate marginal relay 88 and release the connection. By providing double storage of signals, at the cord circuit 5 transmitter and at the distributor MD, the circuits are simplified and the several transmittersmay each be operated at its most efflcient speed. If desired, however, other methods of interconnecting start-stop transmitters .to the multiplex 10 channels may be employed.

Incoming messages over the trunk I8, as shown in Fig. 1, are recorded by the reperforator RES and subsequently repeated through a. selected switchboard circuit, either to local or spillover re- 15 ceiving apparatus or to another office, by the tape transmitter TT5. The incoming messages over the duplexed circuit I4 are likewise stored and repeated by the reperforator RRB and tape transmitter ,TTS through the instrumentality of the 20 associated cord circuit. While only one reperi'orator is shown for receiving messages over the trunk I8, ordinarily the apparatus shown would be duplicated for each operating channel of each multiplex distributor in the central office. Like- 25 wise the receiving equipment shown in connection with the duplexed circuit It would be .duplicated for each similar circuit terminating at the central omce.

Special services As pointed out above, an auxiliary storing device such as the reperforator RM (Figs. 1 and 6) is provided which is accessible through the switchboard at the central office. This reperforator is 35 preferably of the type which both reproduces the printed characters of the message and records the code signals in a form adapted to operate the associated tape transmitter TM. The tape transmitter 'I'Iil may be connected to the switchboard through a cord circuitsimilar to those shown in Fig. 8 so'that the stored messages may be subsequently repeated over any of the circuits termimating in the switchboard.

The reperforator RRd may be employed as a spillover storage device to clear out messages re ceived by the reperiorators RRI, RR2, BB3, RR5 and RRG, when traiiiic conditions are such that these messages cannot be relayed promptly and also for [handling deferred messages and other 56 special services. In order to transfer a message to the 'reperforator RRl, the plug i5 is inserted into the jack it connected to the conductors a and b of the switchboard multiple. Upon the insertion of the plug in the jack, a circuit is closed through the winding of relay I85 (see Fig. 6). switch I88 corresponding to switch II2 of Fig. 4, conductor b of the switchboard multiple, sleeve contacts of plug I5 and jack I8, right hand winding of'testrelay I9, resistance 88 and right hand armature and back contact of relay It to ground at the circuit allotter CA. If the reperforator RR! is not busy, the test relay 19 becomes energized as described above and initiates the operation of the associated tape transmitter to send 65 the message signals over the tip circuit of the connecting plug and conductor a of the switchboard multiple.

, The energization of relay I85'closes, through its left hand armature and front contact, a locking 7 circuit that is independent of the switch I88 and, through its right hand armature and front contact, the transmitting circuit from the contacts of the tape transmitter to the operating magnet I8I of the reperforator RRI. Relay I88 associated 75- with reperforator RRl .is normally energized through a circuit including resistance I89, winding of relay I81 and the right hand armature and back contact of relay I85. Upon the energization of relay I85 as described above, relay I88 becomes deenergized and closes through its right hand armature-and back contact the circuit of signal lamp I98. The lighting of signal lamp I90 calls the attention of the operator or attendant at the central oflice to the message stored in the reperforator BRA. Relay I88 closes through its left hand armature and back contact a short-circuit around its own winding so that the lamp I98 remains lighted until, the switch I! is opened by theattendant. When the end-of-m'essage signal is received by the reperforator RRA, the contacts I92 are closed, thereby short-circuiting the resistance I88 and initiating the restoration of the cord circuit as described above. Relay I85 becomes deenergized thereby interrupting the transmission circuit to reperforator RRA. When the attendant clears out the message stored by the reperforator RRA, the switch I9I may be opened to permit relay I88 to become energized thereby extinguishing the lamp I98.

The multiple jack equipment associated with the local receiving position is identical with that described above at the spillover position except that a printer RP4 is provided instead of the reperiorator REA. Incoming messages for delivery from the central oflice are relayed through v the switchboard to the receiving printer RPd in precisely the same manner as messages are transferred to the reperforator RR4, and the messages are printed and attached to a message blank or prepared for delivery in any desired manner.

Multiple storage transmitters are provided at the branch ofices,

secondary storage is employed wherethe signals v v are repeated over a multiplex channel of a circuit having synchronous distributor apparatus.

In. the application of reperforator-switching systems to the practical requirements of telegraph service, it may sometimes be desirable for operating or other reasons to utilize double storage in connection with transmission into both multiplex channels and circuits having start-stop synchronous terminal equipment. In that case the outgoing lines I0, II, I2 and I4 are also provided .55 at the sending sides with storage-transmitters 'of the same character as described above in connection with the multiplex channels of line I3 except that the tape transmitters are of the type designed to operate start-stop printers and may be similar to the transmitters TTI, TT2 and TT3.

The operation of this equipment would be similar to that described above in connection with transmission over the line I3.

One advantage of this arrangement resides in the fact that the transmission rates between connected transmitters and reperforators located in .the central office are not subject to the speed limitations governing the operation of apparatus connected by long lines and therefore may be materially higher-than the rates of transmission on some or all of the inter-oiiice circuits, as

pointed out above in connection with transmission over multiplex channels (Fig. 6).

A further modification embodying the inven-.75

tion and involving triple storage of message signals is illustrated diagrammatically in Fig. '7. In this system, intermediate storage reperforators are provided between the receiving reperforators and the reperforators associated with the outgoing lines. Such an arrangement would be desirable, for example, in a large oflce where a switching operator or groupof operators could not be expected to route all messages directly to the proper outgoing line or channel.

As shown, the oifice or exchange is divided into sections A, B and C. The receiving section A is divided into a multiplex group Zilil, a trunk and way simplex group 20!, a simplex city group 2612 and a city or local perforating and relay group 2513. At each group of the receiving section a switchboard section 204 is arranged for relaying messages. The group 200 contains printer reperiorators and tape transmitters as described above in connection with the system shown in Figs. 1-6 for storing messages received over multiplex channels terminating at the ofiice. In general, the storage, repeating and switching units may be of the same character as those already described. The group 29! of the receiving section A contains printer reperforators and tape transmitters connected to incoming simplex trunks and way circuits and group 292-contains similar apparatus for storing and repeating messages from local or city offices. The group 293 contains the local sending equipment such as keyboard perforators and tape transmitters.

The intermediate section B of the exchange is divided into three groups 2535, 203 and 26 Group 265 contains storing and repeating units for relaying messages over simplex trunks and ways 'or destined for manual relay or local delivery. Group 286 contains similar equipment for handling local or city trafic and group 20? contains storing and repeating equipment for handling special messages, such as spillover or deferred messages, misroutes, etc. The reperforators in each group ofthe intermediate section B may be connected to calling lines from switchboard 204 by finder switches 208 in order to reduce the number of storing and repeating units required as in the case of concentrating systems in general use for connecting an idle one of a group of printers or receiving units to a calling line. A switchboard section 208 is provided for each of the groups in the intermediate section B for selection of the proper relay channel by the intermediate operator.

The sending section C of the exchange is divided into groups 2H3, 2H, ZIE and 253. The multiplex sending group 210 is accessible through multipled jacks of the switchboard sections 20d and contains reperforators and tape transmitters for storing and repeating messages over outgoing multiplex channels. The groups 2 and 212 contain similar equipment for relaying messages over simplex trunks and way circuits and over simplex lines to local or city oiiices, respectively. The group 213 contains printers for recording local messages for delivery or manual retransmission. Each of the groups in the sending section C may be provided with finder switches 214 similar to the Switches 208, thefinder switches in groups 2), 2H and 2|2 being each individual to a multiplex channel, a simplex trunk and a simplex local circuit selected by the A operator, respectively.

In the system illustrated, the switching operator at section A is required to difierentiate between local or city messages and messages to be aieaeir relayed over outgoing trunks or channels. In the case of messages to be relayed over multiplex channels, the operator is further required to select the proper channel, the multiplex sending group 2H0 being accessible through the switchboard sections 203. In a large exchange, an operator could not be expected to route all messages to the proper sending circuits and in the arrangement shown, the messages to be retransmitted over simplex trunks and way circuits and local simplex lines terminating at the exchange are routed to groups 295 and 206 at the intermediate section B. Likewise cleierred or spillover messages are routed to group 28'! at the intermediate section. If desired, the messages to be relayed over multiplex channels could also be routed to the intermediate section B but in most offices a large proportion of the load is carried by the multiplex channels and therefore the apparatus required at the intermediate position is greatly reduced by routing such messages directly from the receiving section A to the sending section C.

' The switching operator at group 205 of the intermediate section Bis required to select the proper simplex trunks individually at group 2H of the sending section C and to select group 213 in the case of messages to be manually retransmitted. The switching operator at group 206 of the intermediate section is required to select the proper local or city circuit for local messages and the operator at group 297 handles spillover messages, misroutes, etc., as indicated diagrammatically. If an A operator cannot determine the proper routing for a particular message or obtain access to the desired channel within a reasonable time, such messages may also be routed to group 2M thus reducing the delay in transmitting other messages received subsequently on the same reperforator.

It will be apparent that by providing an intermediate switching section B, the size of the switchboard at the receiving position A is reduced and the duties of the A operator in respect to routing of messages are brought within reasonable limits thereby minimizing-the chances of delays and errors in relaying messaages. The system has the further advantage that a temporary overloading of one of the simplex trunks or city circuits does not result in a delay in clear ing out a message destined for the overloaded circuit from the transmitter at the receiving position with a consequent delay in the transmission of other messages stored by the associated reperforator. The occurrence of such delays in clearing traffic from the receiving reperforators is likely to result in an accumulation of trafdc for other trunks and cause temporary overloading which is reflected back upon the transmitters at the receiving position. Thus an abnormal increase in messages awaiting transmission at the receiving position is likely to occur. Under ordinary conditions this difiiculty is avoided by storing messages destined for overloaded circuits at the intermediate section of the exchange as described above.

As pointed out above, the invention is not limited to the specific types of storing, repeating or switching apparatus herein described.

.. going channel.

2. In a telegraph system, a central station, a plurality of telegraph channels terminating at said central station, a character storage device individual to each incoming channel for storing character signals receivedthereover, a plurality of outgoing telegraph channels at said central station, a character storage device associated with each outgoing channel, manual switching means for connecting anyof said first mentioned storage devices to any of said second mentioned storage devices for transmitting characters from said first mentioned'storage devices to said'second mentioned storage devices, means controlled by predetermined character signals so transmitted for interrupting transmission of characters from said first mentioned storage devices and means for transmitting characters from each of said second mentioned storage devices over its associated outgoing channel.

3. In a telegraph system, a central station, a plurality of telegraph channels terminating at said central station, a character storage device individual to each incoming channel for storing characters received thereover, a plurality of outgoing telegraph channels at said central station, a character storage device associated with predetermined ones of said-outgoing channels, switching means for successively connecting the first mentioned storage devices to said second mentioned storage devices or directly to an outgoing channel for transmitting characters from said first mentioned storage devices to said secondmentioned storage devices or to said outgoing channel, means controlled by predetermined character signals so transmitted for interrupting transmission of characters from said first mentioned storage devices and means for transmitting characters from each of said second mentioned storage devices over its associated outgoing channel. v

4. In a telegraph exchange system, an office, incoming and outgoing lines terminating thereat, signal storage devices associated with the incoming lines, other signal storage devices associated with the outgoing lines, means for repeating the signalsstored in one of the storage devices associated with incoming lines and for storing said signals in one of said other signal storage devices and means for repeating the signals stored in said one of said other signal storage devices over an outgoing line.

5. In a telegraph exchange system, an omce, incoming and outgoing lines terminating thereat, a receiving reperforator operable over one of said incoming lines, means including a second reperforator for transmitting signals over an outgoing line at a predetermined rate and means for operating said second reperforator at a difierent rate in. accordance; with the signals recorded by the first mentioned reperforator.

6. In a telegraph, exchange system, an oflice,

character storage devices sage signals recorded by the first mentioned reperforator.

'7. In a telegraph exchange system, an oflice, an incoming line and a plurality of outgoing lines terminating thereat and means including selective switching devices for repeating message signals received over said. incoming line over any one of said outgoing lines, said means further including a receiving reperforator operable at a predetermined rate by signals transmitted over said incoming line and a secondreperforator associated with the selected outgoing line operable at a rate higher than said predetermined rate in accordance with signals stored by said receiving reperforator.

8. In a telegraph exchange system, an offlce, incoming and outgoing lines terminating thereat, a group of signal storage devices associated with the incoming lines, a second group of signal storage devices associated with the outgoing lines, a third group of signal storage devices, means for repeating and storing signals from the first group of signal storage devices to the second group, and means for repeating and storing signals from the first group of signal storage devices to the third group and for thereafter storing said signals in the second group of signal storages devices.

9. In a telegraph system, a central station, a plurality of incoming telegraph channels terminating at said centralstation, character storage devices associated with said incoming channels for storing characters received thereover, a plurality of outgoing channels at said central station, character storage from said first mentioned storage devices to said second mentioned storage devices, means for adding supplemental character signals to each message group transmitted by said first storage devices and means for transmitting characters from each of said second mentioned storage devices over its associated outgoing channel.

10'. In a telegraph system, a central station,

a plurality of incoming telegraph channels ter-' devices associated with I predetermined of said outgoing channels, meansfor transmitting message groups of characters said first mentioned storage devices at the end of each message group and means for transmitting characters from each of said second men tioned storage devices over its associated out-,

going channel. v

11. In a telegraph system, a central station, a plurality of incoming telegraph channels terminating at said centralstation, a plurality of for storing character signals received thereover at one rate, a plu-

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