US2347831A - Communication system - Google Patents

Description

May 2, 1944' F. s. KINKEAD ETAL, 2,347,831

COMMUNICATION SYSTEM Filed Aug; 28, 1941 5 Sheets-Sheet 1 I30 TRANS. START POLARIZED TRANSMITTER n/smiauran l alll l "412% A TTOBNEV 39440 F. s. KINKEAD EAL 4 COMMUNICATION SYSTEM Filed Aug. 28, 1941 5 Sheets-Sheet 2 POL ARIZE E S. KIN/(E40 INVENTORS J.A. KRECEK WRJOU/VG JR.

,4 T TORNE V y 1944- F. s. KINKEAD' ETAL COMMUNICATION SYSTEM 5 Sheets-Sheet s Filed Aug. 28, 1941 Nab men May 2, 1944. F. s. KINKEAD ETAL COMMUNICATION SYSTEM Filed Aug. 28, 1941. 5 Sheets-Sheet 4 F. s. KIN/(E40.

m x JW m w m B w w km v mt ATTORNEY y 1944- F. s. KINKEAD ETAL 2,347,831

COMMUNICATION SYSTEM Filed Aug. 28,1941 5 Sheets-Sheet 5 canncrs A T TOR/VEV Patented May 2, 1944 2,347,831 COMMUNICATION SYSTEM Fullerton S. Kinkead, New York, and Joseph A. Krecek, New Rochelle, N. Y., and William R. Young, Jr., Summit, N. 1., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New .York

Application August 28, 1941, Serial No. 408,605

45 Claims.

This invention relates to communication systems and more particularly to telegraph systems in which a plurality of telegraph stations are connected to a telegraph transmission path.

It is the object of this invention to provide an improved telegraph transmission and switching system in which the control of the various stations connected to a telegraph line is improved so as to more fully utilize the entire line time for the transmission of telegraph signals representing messages.

Another object of this invention is to provide a telegraph system in which the distribution of the line time between the various stations connected to a line may be readily controlled and varied from time to time so thatthe'distribution of time between. the various stations may be arranged somewhat commensurate with the messagematerials to be transmitted from the various stations.

A feature of this invention relates to means for controlling a plurality of geographically separated tape or storage telegraph transmitters for transmission over a two-Way telegraph transmission path in such a way that they cannot interfere with each other.

A feature of this invention relates to an arrangement in which each station or the transmit ter located thereat is given an opportunity to transmit a specified interval of time after the transmission of the end of the last or preceding message transmitted from another station. In accordance with a feature of this invention a time delay circuit is provided at each of the stations having a different delay period or interval at each of the stations connected to a common transmission path.

Another feature of this invention relates to circuit arrangements and apparatus for providing an opportunity for the transmitters at each of the stations to transmit over the circuit before any transmitter may transmit over the circuit a second time. In accordance with another object of this invention a second time delay circuit is provided at all butone of the stations con nected to a common transmission path having a delay period longer than the longest delay period of the delay circuits of but shorter than the delay period of said one station.

Another feature of this invention relates to switching apparatus for using said timing circuits alternately.

Another feature of the invention is an arrangement for terminating the transmission from any station at the completion of the first message transmitted therefrom.

Another feature of the invention is to provid an arrangement for terminating a transmission from any station at the completion of the first message after a station hasv been transmitting for a predetermined interval of time. v

Another feature of this invention is an arrangement at a control station for repeatedly reconditioning the timing apparatus at. the respective stations so that each station is periodically provided with an opportunity to transmit messages over the system when desired.

Another feature of this invention relates to apparatus for enabling the attendant at any of the stations to transmit a break signal over this circuit to interrupt the transmission over the system then in progress and seize control for the transmission of any urgent messages or information over the system.

Another feature of this invention relates to arrangements for permitting an attendant to insert a tape in the tape controlled transmitter at the respective stations and condition the circuit so that at the next opportunity provided the message will automatically be transmitted without any further attention or eifort on the part of the attendant.

Another feature of this invention relates to providing suitable lamps or other type of signals before the attendants at the various stations to enable them to readily see at a glance the condition of the circuit and their equipment under the various conditions normally encountered during the transmission of messages over the transmission channel.

Another feature of this. invention relates to apparatus and circuits for automatically and periodically transmitting a conditioning signal from the control station to the other stations connected to the system.

Other objects and features, in addition to the foregoing objects and features of this invention. the novel features of which are specifically set forth in the claims appended hereto, may be more fully and more readily understood from the following description when read with reference to the attached drawings, in which:

Figs. 1 through 4 illustrate details of a typical embodiment of this invention;

Fig. 5 shows the manner in which Figs. 1 to 4 are arranged adjacent to each other to illustrate a typical embodiment of this invention; and

Figs. 6, '7 and 8 show mechanical details of certain of the receiving and transmitting appa- As may be readily appreciated by those skilled in the art, any suitable number of outlying stations may be connected to the systemin order to fully and economically load the transmission line extending between the stations. As shown in the drawings, a full metallic trans mission path is, shown extending to all of the stations of the system over which these stations may both transmit to receive messages. 'As will be readily understood by those skilled in the art, this transmission path may include any suitable type of telegraph or impulse transmission system including both grounded and full metallic circuits, telegraph channels of composited telephone and telegraph lines, voice frequency carrier current systems, high frequency carrier currentsystems, radio channels, etc. This transmission channel may alsoinclude any combination of the various types of systems as well as the usual types ofterminal and interconnecting equipment. The channel may also include any suitable typesof repeaters provided with any of the features which may be necessary or desirable, such as, bias control and gain control. These channels may also include regenerating repeaters and all other types of equipment and accessories necessary or desirable for proper transmission of telegraph signaling impulses over the system. These systems and related equipment and apparatus may be operated in their usual manner. I v H Inasmuch as all of these types of systems are well understood in the art and operate in their usual manner, it is not thought wise to further complicate the disclosure of this invention with the details of all of the possible types of transmission systems in combination with which it may be employed. The essential requirement of the transmission system extending to all these stations is that when current flows through the transmission circuit at any one of the stations it will flow through all of them and when the flow of current through any loop of the system extending from anyof the stations isinterrupted.

it will be interrupted at all of the other stations as soon as these various current conditions may be transmitted over the system from one of the stations to the other stations.

Briefly, in accordance with the specific embodiment" of this invention, the attendant at the outlying stations will perforate tape in accordance with the message to be transmitted over the system. Details of typical keyboard perforating mechanisms and associated transmitters suitable for use in this invention are described in United States Patents 1,965,572 granted to Burcky et al., July 10, 1934; 1,965,602 granted to Lake, July 10, 1934; and 1,969,891 granted to Lake et a1., August 14, 1934. 1 The above patents are hereby made a part of this application as if fully included and set forth herein.

Usually preceding the message the address or designation of each message is perforated in the *tape and following each message an end-of-mesnals cause the tape to be stepped out of the perforating apparatus, provide a sufiicient separation between the messages to permit the tape to be torn between messages, and also provide time for switching circuits at the various stations to 'function between messages without mutilatin any of the characters of the messages. Letters signals may also be inserted after the switching or directing codes to provide suflicient time for the circuits to function so they will be ready to respond to the next significant code combination. In addition, near the beginning of .each message a carriage return signal is also perforated on the tape. The carriage return signal is usually perforated in the tape to properly positionthe receiving equipment for responding to the text of theymessage as well as to print the heading and other information preceding a message in the proper position on the page. The first carriage return signal of each message in addition to conditioning the receiving equipment is also employed to control certain of the switching circuits as described hereinafter. After the attendant has perforated this tape, she'will insert it in'the transmitter at her station and operate a key entitled transmitter start key. Thereafter the message will be transmitted from that station in its proper turn.

In order to provide means for transmitting these messages in turn from the respective stations, a timing circuit is provided at each of the stations-which is arranged to be controlled by means of signals received over the system. In the specific embodiment of this invention shown in the drawings the operation of the timing circuits at all of the stations is initiated by a pause in the transmission following the end-of-message signals following each message. If no further signals are transmitted over the system after an end-of-message signal, and the system remains in the normal marking condition indicating that the transmission path is operative, one of the stations will be then given an opportunity to transmit at the end of a predetermined interval oftime If a tape has been inserted in its transmitter and the transmitter-start key operated prior to the termination of this interval of time, the transmitter at this station will be started at the termination of thisv first interval of time. If no tape has been inserted in the transmitter at this station and the transmitter start key has not been operated at this time, this transmitter will not be started. As shown in the drawings the timing circuits at the respective stations are arranged so that the delay time at the stations may be readily varied so that the order of transmission may be readily controlled and so that stations may be readily added and removed from the common transmission path.

To effect the necessary and desirable changes the straps on the various condenser groups are altered. Thus the straps provided on condensers I41 and 241 determine the time and order of transmission from these stations. These straps are so provided that the delay times at the various stations are all different. However the total number of stations connected to a common path determine the straps and thus the size or the combined condensers I l! and I48 and 241 and 248. At the completion of a second and longer interval of time a transmitter at another station will be started provided a tape has been inserted therein and the transmitter start key operated. After all of the stations have been thus given an opportunity to transmit,- without transmission from any of them, an end-of-message signal is automatically transmitted from the control station which again initiates the above cycle of operations.

If any of the stations have messages to transmit that have been inserted in the transmitter and the transmitter start key operated, these messages will be transmitted over the system. Upon the completion of the transmission of these messages an end-of-message signal is transmitted over the system followed by a pause which again initiates the operation of the timing equipment at each of the stations. Additional timing equipment at each station is provided in addition to the timing apparatus at each station referred to above, and upon transmission from that station, or after the time interval assigned to that station has passed without transmission therefrom, the second or the combined first and second so that the timing equipment does not respond to the same time interval as before. Instead, the timing equip ment at this station now requires a much longer time interval before it will respond so that all of the other stations on the system will be given an opportunity to transmit before the above cycle is repeated and tranmission initiated from any of the stations which previously transmitted.

A third timing circuit is provided at each of the stations to time the length of transmission from those stations. By operating suitable keys in these circuits, the attendant at these stations may condition the equipment for the transmission from that station during different intervals of time. At the completion of this interval of time the transmitter will be stopped at the end of the message then in progress of transmission and other stations of the system will then be given an opportunity to transmit.

In addition to the tape transmitters and keyboard perforator located at each of the stations, a keyboard transmitter is provided for emergency or urgent transmission of messages over the system. A break key is provided at each of these stations so that the operator or attendant thereat can stop the transmission over the system and take control and transmit the n cessary information or urgent messages. In addition, a receiving device is located at each of these stations which records all of the messages transmitted over the system. At the control station a typing reperforator is provided as a receiving device. All of the messages, except th messages transmitted from the control station, are recorded by this typing reperiorator both as printed matter and as perforations in a tape. This tape may then be carried to any other transmitter located in the control station and associated with any other line and the messages transmitted over these lines as required. The perforator need not completely perforate the tape but may only partly punch the tape so as to leave small tabs at each perforation attached to the tape upon which the message maybe printed. These tabs will facilitate the reading of the printing on the tape by the operator so that she may readily determine the transmitter to which the tape should be taken for transmission over the associated line. v

Starting the first station First assume that power has been applied to the system and that the various motors driving the equipment are operating. In addition, assume that switch H2 shown in Fig. 1 at station A and switch 2I2 at station E shown in Fig. 2 andswitch M2 at station C have all been closed. Further assume that the attendant at each of these respective stations has inserted a tape I03 in transmitter I0! at station A, a tape 203 in transmitter 213! at station B and a tape M13 in transmitter 481 at station C. Further, assume that the attendant at each of these respective stations has operated respective transmitter start keys I3I, 23! and 3%. The operation of key I3! at station A completes a circuit for the operation of relay I35 from battery through the Winding of relay i335 and contacts of key I3! to ground through the closed'contacts H3. Relay I35 in operating also completes a circuit for maintaining itself operated from battery through its Winding, the break contacts of relay I36 to ground through contact H3. The operation of relay IE5 at this time completes a circuit for lighting lamp I30. If relay MI is not released when key I3I is operated, relay I35 operates and locks operated. Then when relay I4I releases a circuit is completed for the operation of relay I35 from ground through contacts II3, the break contacts of relay I36, the left-hand operated contacts of relay I35 to battery through the right-hand innerbreak contacts of relay MI and the windingof relay I36. Relay I36 in operating at this time first completes a circuit for maintaining itself operated, as described hereinafter. However under the assumed conditions relay Isl will be released at this time so the operation of key I3! also completes a circuit for the operation of relay I36, from battery through the winding of relay I36, the right-hand inner break contacts of relay I41, th operated contacts of key I3l, to ground through the contacts II3. Inasmuch as tape I03 has been inserted in the transmitter IQI, contacts H3 will be closed at this time. Consequently, relay I36 will operate and complete a circuit for maintaining itself operated from battery, through its winding and right-hand inner operated contacts to ground through the closed contacts H3. Relay I36 in operating interrupts the locking circuit of relay l35 which relay releases. Relay I35 in operating, also completes an obvious circuit for lighting the transmitter start lamp I30.

Similarly, the operation of key 23I at this time at station B completes a circuit for the operation of relay 236 which relay in turn completes a circuit for maintaining itself operated and for lighting lamp 239. The operating circuit for relay 236 may be traced from battery, through the winding of relay 236, the right-hand inner break contact of relay 2, operated contacts of key 23! to ground through closed contacts 2I3. At station C, the operation of the transmitter start key 386 completes a circuit for the operation of relay 326, from battery, through the winding of relay 325, the operated contacts of the transmitter start key 356 to ground through closed contacts 653. Contacts H3 will be closed since tape @533 has been inserted in the transmitter 40L If, as assumed, relay 3I9 is released at this time relay 320'is also operated when key 306 is'operated. V

7 When power is applied to ,the system and the transmission path between all the stations established, the line relays I26, 226, 30I and 302 are all operated to their'marking positions. In addition, the repeating relays I20, 220 and 303 are likewise operated to their marking positions.

'All of these relays are provided with a biasing winding which tends'to operate them to their spacing positions but the effect of the current flowing over the line through their line windings overcomes the efiect of the current through their biasing windings and causes the armatures of these relays to be held to their marking positions. i

Under these circumstances, the operation of the'timing circuit at each of the stations A, B and C is initiated. That is, upon the application of power to the system condenser 241 at station E, condenser I41 at station A and condenser 344 at station C start to charge. In addition, upon the application of power to the system, the filament circuits of the tubes I44, 244 and 324 are energized, thus conditioning the respective vacuum tubes for operation. Prior to the application of power to the system, condensers I41, 241 and 344'had both their termi-' nals at ground potential because the positive potential is cut off. The potential of the grids or control elements in the respective tubes are controlled by the potential of the upper terminal'of these'condensers. Since at the start the upper terminal of these condensers and thus the grids are at ground potential while the filaments of the tubes areat a positive potential with respect to ground, the grids will be negative withrespect to the filaments and prevent the flow of sufficient current through the tubes to operate the respective relays I43, 243 and 3I8.

When power is applied to the system at station B, the upper terminal of condenser 241 will start to charge to a positive potential through the high resistance 245 when the line relay 226 is in its marking position and relay 234 released as under the assumed conditions. The time constant of resistance 245 and condenser 241 together with the constants of tube 244 and the potentials applied thereto are such that it requires approximately one second for the upper terminal of condenser 241 to charge sufliciently I quires approximately five seconds for the upper terminal of this condenser to acquire a sufficiently high positive potential through the high resistance 345 to cause. tube 324 to pass sufiicicnt current to operate relay 3I3. Thus the timing circuit comprising the condenser corresponding to condenser 241 and the resistance corresponding to resistance 245 has different constantsat each of the stations connected to the system.

Consequently, at the end of approximately one second, relay 243 will operate but relay I43 at station A and relay 3I8 at station C will not operate.

The operation of relay243 at station E completes a circuit for the operation of relay 24I from ground, through the operated contacts of relay 243, the left-hand break contacts of relays 231 and 242 to battery through the winding of relay 24I. The operation of relay 24I completes a circuit for maintaining itself operated from battery, through its winding and left-hand inner operated contacts to ground, through the operated contacts of relay 243. The operation of relay 24I interrupts the operating circuit of relay 236'so that this relay. cannot be operated at this time. However, under the assumed conditions, it has been previously operated and is maintained operated at this time by current flowing through its locking circuit.

The operation of relay 24I completes a circuit for the operation of relay 238 from battery, through the winding of relay 238, right-hand outer operated contacts of relays 236 and 24I to ground, through the break contacts 224. Relay 238, in operating, completes a circuit for maintaining itself operated from battery, through its winding, the right-hand outer operated contacts of-relay 236, the left-hand outer operated contacts of relay 238 to ground, through the break contacts of relay 240. A second locking circuit for maintaining relay 238 operated may also be traced from battery, through the winding of relay 238, the right-hand-outer operated contacts of relay 236, the center set of left-hand operated contacts of relay 238, to ground, through the break contacts 224.

The operation of relay 238 also completes a circuit for operating the start magnet 209 of transmitter 20I from ground through the righthand inner operated contacts of relay 238, the left-hand break contacts of relay 233, closed tape control contacts 2I4, the closed switch 2I2, winding of start magnet 209 to battery through the closed contacts 2I6. r

The operation of start magnet 209 attracts its armature 2I6 which in turn disengages'the stop cam 2, thus releasing the brush arm 206 of the distributor 201 of transmitter 20I for rotation. The rotation of brush arm 206 causes the message, stored in tape 203 together with any address or directing information preceding the message to be transmitted over the transmission system extendingrboth to stations A and C. The message is recorded by the receiving apparatus I02 at station A, 7202 at station B, and the printing reperforator 402 at station C.

Upon the transmission of the first start impulse from,transmitter 20I in response to the rotation of brush arm 206, relays I26, 226 and relays 30I and 302 are operated to their spacing positions. At station B relay 226, in operating to its spacing position, completes a cirout for the operation of relay 239 from battery through the winding of relay 239, the right-hand break contacts of relay 234 to ground through the spacing contact and armature of relay 226. Relay 239, in operating completes a circuit for maintaining itself operated from battery, through its winding and right-hand operated contacts to ground through the left-hand inner operated contacts of relay 238.

Relay 23:9, in operating, completes anobvious circuit for the operation of relay 234. Relay 234, in operating, completes a circuit for maintaining itself operated from battery, through its winding andright-hand operated contacts to ground, through the spacing contact and armature of relay 226. Relay 234 is slow in releasing so that it will be maintained operated by current flowing through its locking circuit during the continuous transmission of signals over the telegraph transmission system. During the continuous transmission of signals over the system, the armature of relay 226 moves alternately between its marking and spacing positions in response to the signals and will be in its spacing .248 is discharged prior to the operation of relay cs2, when it is connected in parallel with con- .denser 24? it will cause the potential of the upper terminal of condenser 241 to fall to such a value that current through tube 254 will be reduced so that relay 243 will release and interrupt the locking circuit of relay 2. Relay 257i releases at this time but relay 242 is maintained operated by current flowing through its locking circuit.

Generally, relay 234 will operate after relay 242 has operated and relay 243 has released. Consequently, the subsequent operation of relay 23% connects ground to the upper terminal of condensers 24'! and. 248 and thus interrupts the charging .of the upper terminals of these condensers andprevents the flow of current through tube 2%, .thus preventing the operation of relay *253 at this time.

Thereafter the message will be transmitted from station B by the transmitter 2M in accordance with the signals stored in tape 233.

When the-first spacingsignaltransmitted from station B arrives at station A, relay 123 will be operated to its spacing position where it completes acircuit for the operation of relay I39 from battery through the-Winding of relay I33, the right-hand breakcontacts .of relay 134 to ground through the spacing contact and armature of relay J26. Relay -i39, inoperating, completes ,a circuit for maintaining itself operated v from battery through its winding and righthand operated contacts, the center set of lefthand break contacts of relay I38 to ground through the break contacts I 24.

Relay I39, in operating, completes a circuit for the operation of relay I34. :Relay I34, in operating, completes .a circuit for .maintaining itself operated from battery through its Winding and right-hand operated contacts to ground through the spacing contact and armature of relay iZB. Relay I23 follows the signals transmitted over the transmission path and during the continuous transmission of signals overthe system will be in its left-hand position sufficiently long to maintain the slow-release relay I33 operated.

Theoperationof relay I3l connects ground to the upper terminal of condenser J4? and thus completely discharges thiscondenser in a very short interval of time. So longmas relay -for the operation of relay 3I2. operating, completes a circuit for maintaining I34 remains operated, ground remains connected to the upper terminal of condenser I41 and thus prevents relay I43 from operating. Thereafter, the circuitsat station A remain in this condition during the transmission of the first message from station B.

When the firstspacing signaltransmitted from transmitter 2M arrives at station C it will cause relays 3M and 3&2 to be operated to their spacing positions. The operation of relay 302 to its spacing position connects ground to the upper terminal of condenser 344 which discharges condenserfiil'e. During the transmission of "the signals, relay 3E2 operates to its spacing position sumciently often to maintain condenser 343i! substantially discharged because this condenser discharges very rapidly and charges quite slowly through the high resistance 345. Due to the .fact that condenser 344 remains substantially discharged, relay 3| 8 cannot operate during the transmission from transmitter ZilI.

The operation of relay 36I to-its spacing positioncompletesa circuit for theoperation of relay 343 from battery through the winding of relay i313 and the right-hand break contacts of relay 3l2 to ground through the spacing contact and armature of relay 30L Relay 3I3 when operating completes a circuit for maintaining itself operated from battery through its winding and the break contacts of relay 3 I5 to ground through the right-hand operated contacts of relay 3I3. Relay BIS, in operating, connects condenser 343 in parallel with condenser 344. -However, relay 332 follows the signals and is operated to its spacing position a substantial proportion of the time the signals are transmitted over the system. These condensers will therefore remain substantially discharged.

Relay -3I3, in operating, completes a circuit Relay 3I2, in

itself operated from battery through its'winding and right-hand operated contacts to ground through the spacing contact and armature of relay 3E5. Relay 3E2 is slow in releasing so that it will be maintained operatedby current flow-,- ing in this locking circuit during the time signals are being continuously transmitted over the transmission path.

Thereafter, the circuits atstation C remain in substantially this condition during the remainder of the transmission of the message from station B.

Transmission The signals recorded in the tape 1203 are then transmitted by the transmitter -2flI over the transmission path to stations Aand C. The repeating relays I20 at station A,.2 20 at station B and 303 at station C follow the signals and. repeat them to the respective selector magnets H9, 2 I9 and G53. Magne t-I I9 causes the receiving apparatus at station A to recordthesignals transmitted by the transmitter 2M. The selector ma net ZIQ at station E causes signals to he likewise recorded at station E toprovide a home copy-of;the-message transmitted-over the system. Details of typical receiving apparatus suitable for use at the various stations are describedin-Unitedrstates Patents 1,745,633granted February 4;, l93Q, to S. Morton et al. and 1,904,164 granted April .18, 1-933, to S. Morton et al. The disclosureofthesepatents-is hereby made apart of this application as if fully includedand set forth herein.

Magnet 453 causes the printing .reperf orator 402 to bothprint'thesignals-upon thetapearid to perforate the tape in accordance with the various elements of the signal. The tape from the recording device 482 will then be available for insertion in transmitter 40I or a similar transmitter connected withany other transmitting path at the control station.

The details of the other transmission paths which may terminate atthe control station have not been disclosed in this application. It is to be r understood, however, that they may include paths similar to the one disclosed herein or any other suitable; type of transmission circuit together with a transmitter capable of transmitting signals in accordance with stored representations of sig-, nals constituting messages.

Returning nowjto the operation of equipment .at the transmitting station B,it should be noted that a number of keys 253, 254 and 255 are provided. If 'none of thesekeys are operated, positive potential is applied to the. grid of tube 25I upon the operation of relay 238 which removes the ground connected thereto. The operation of relay 238 also completed the filament circuit to tube 25L Consequently, a short interval of time after relay 238 has operated, tube 25I will be energized and pass sufiicient current to operate relay 249. Relay 249 in operating completes an obvious circuit from ground for the operation of relay 240. Relay 240, in operating, interrupts one of the locking circuits holding relay 238 operated. Relay 238, however, doesnot immediately release because it is maintained operated by current flowing through the locking circuit extending through the break contacts 224.

' However, had one of the keys 253, 254 or 255 been operated prior to the operation of relay 238, the. associated condensers 256, 251 and 258 would have been charged so that their upper terminals .will be at ground potential and their lower terminals at the potential of the positive battery.

Thepotential of the grid of tube 25I is controlled .by the potential of the upper terminal of these condensers so that under these circumstances, withthe grid at ground potential, insufficient currentwill pass throughtube 25I to cause relay 249 to operate. Upon the operation of relay 238, as described above, groundv isconnectecl to the lower terminals of the condensers 256, 251 and 258 in a path extending from ground throughthe break contacts of relay 253 and right-hand outer opercondensers, the potential of-the grid of tube 25! is'made morenegative at' this time. Conse quently, tube 25I will conduct substantially no space current at this time. 7

The operation of relay 238 also removes the ground connected to the upper terminals of the condensers 'and'thus removes a short circuit from around the high resistance 259 whereupon the upper terminals of many of the condensers con nected to the circuit begin todischarge and then become charged to a positive value. The time constants of resistance 259 and the condensers 256, 251 and 258 together with the value of the bias and other potentials and constants of tube 251 are so related that it requires an appreciable period of time for the upper terminals of these condensers to discharge and to be charged to the positive value required for tube 25I to conduct sufiicient space current to operate relay 249.

.In a typical embodiment of this invention, the

various constants of the-circuits together with the capacity of condenser 258 are such that it requires substantially a minute for relay 249 to operate after relay 238 has operated. The constants of condenser 25! are such that it requires substantially two minutes for relay 249 to operate after relay 238 has operated. The constants of condenser 256 are such that it requires approximately four minutes for relay 249 to operate.

As is well understood, more than one of these keys may be operated at the same time and thus cause a greater delay in the operation of relay 249.

Assume now that one or more of keys 253, 254 or 2-55 were operated previous to the operation of relay 236. Furthermore assume that a number of different messageswere recorded in the tape 203. Assume further that the transmission of these messages individually do not require the entire time interval measured by the timing circuit of the connected condensers 256, 251, 258 and high resistance 259 and tube 25I.

At the end of the first message, the operator will perforate a figures signal followed by an H signal in the tape 203. This figures signal and part or all of the succeeding letters signals followed by the H signal comprise an end of message indication which indicates that the previously transmitted message has been completed.

When the figures signal followed by the H signal is received by the selector magnet 2I9, it will cause contacts 224 to momentarily open. The manner in which contacts 224 are opened in response to the figures signal followed by an H signal is clearly described in the above-identified patents to Morton et al. and need not be repeated here. The momentary operation of contacts 224 at this time interrupts one of the locking circuits of relay 238. If relay 240 is not operated at this time and under the assumed conditions it will not have operated by this time, the operation of contacts 224 will not cause relay 238 to release. Consequently, relays 239 and 234 will remain operated and condensers 24'! and 248 remain discharged. Immediately following the transmission of the figures signal followed by the 'H signal, the signals representing the succeeding message stored in tape 203 will be transmitted from the transmitter 20I since under the assumed conditions, several messages were stored in tape 203 in succession. The circuits at sta tion B thus remain in their previous condition during the transmission of this message.

When the figures signal followed by the H signal which were transmitted at the end of the first message by transmitter 20I are received by the selector magnet N9, the selector mechanism willmomentarily open contacts I24 in the manner described in the'above-identified patents to Morton et al.

The momentary operation of contacts I24 interrupts the locking circuit of relay I39 which relay thereupon releases and interrupts the operating circuit of relay I34. However, if the signals are continuously transmitted by transmitter 20I at this time as they normally will be since a second message will be immediately transmitted by transmitter 20I, relay I 34 will be maintained operated'by current flowing through its locking circuit extending through its righthand operating contacts and spacing contact of relay I28. Near the beginning of the second message from station E, a carriage return signal willbe transmitted. When the carriage return signal is received by the selector magnet II9, it will cause the selector to momentarily close the contacts I23 and complete a circuit for the operation of relay I39. Relay 139 then locks operated in the circuit traced above and completes the operating circuit of relay [34. Thus, the circuits at station B are returned to the same condition they were during the transmission of the first message.

When the figures signal following the first message arrives at station C, it will cause the platen controlled contacts G50 to close. U. S. Patent 2,120,235 granted June 14, 1938, to Beattie et al. shows a typical and suitable apparatus for the operation of platen controlled contacts. The disclosure of that patent is hereby made a part of this application as is fully set out and fully included herein.

Then when the H signal is received, contacts #55! are momentarily operated and complete a circuit for the operation of relay 3 l 5 from ground through the operated contacts 45! and 450 to battery, through the winding of relay M5. The operation of relay 3l5 completes a circuit for maintaining itself operated under control of relay tlS. Relay 315, in operating, also interrupts the locking circuit of relay 313 and thus permits this relay to release. The release of relay EH3 interrupts the operating circuit of relay 312. Relay 3%2, because it is maintained operated due to current flowing through its locking circuit when relay 30! is in its spacing position. Then when a carriage return signal is received by the typing reperforater $92, shortly after the beginning of the next message contacts 423 will be momentarily closed and complete a circuit for the operation of relay 313 from battery, through the winding of relay 311-3 to ground, through the operated contacts 423 and the break contacts 45L Relay M3, in operating, completes a circuit for maintaining itself operated, as described above, and reestablishes the operating circuit through the winding of relay 3 i 2, thus maintaining this relay operated. Thus the same circuits are reestablished at the control station C durin the transmission of the second message from the transmitter 2M at station B as were established during the transmission of the first message from transmitter L The operation of the circuits at the respective stations at the termination of each message and the beginning of the next message transmitted from station E are substantially the same as described above so long as the time assigned for transmission from station B has not elapsed.

End of transmission from one station and starting the neat station If none of the keys 253, 254 or 255 had been operated, relay 246 will operate without substantial delay after the operation of relay 238. If any of these keys had been operated, the operation of relay 2% is delayed as described above.

If all of the messages recorded in tape 293 are transmitted before the end of the time allotted from station E, tape 293 will pass out of the transmitter 2i and permit contacts 213 to open. Contacts 2H3, in opening interrupt the locking circuit of relay 236, thus permitting this relay to release. The release of relay 236 interrupts the circuit of lamp 2%, thus extinguishing this lamp. The release of relay 236 also interrupts both locking circuits of relay 238, thus permitting this relay to release.

If all the messages are not transmitted within the time allotted to station 13, the tape will not run out of the transmitter so contacts H3 will however, does not release at this time lease a short interval of time later.

remain closed. However, relay 240 will operate at the end-0f the time interval assigned to station E for transmission. After rel'ay'249 has operated and the message in progress of transmission at that time has been transmitted, the figures signal followed by the H signal following this message will cause contacts 224 to momentarily open. Under these circumstances, both locking circuits of relay 238 are interrupted. Consequently, this relay will release at this time.

The release of relay 238, due either to the opening of contacts 2l3 or to the operation of relay 2% and the subsequentopening of contacts 224, interrupts the circuit of the start magnet'2ll9 of transmitter 234. Start magnet 269 then releases its armature 2 i 8 and causes the brush arm 2% to come to rest and thus stop transmission over the transmission path. Thereafter, relays l 2%, 226 and 36! and 382 will be maintained in their marking positions. The release of relay 236 and the momentary operation of contacts 224 interrupt the locking circuits of relay 239 and thus permit this relay to release. The release of relay 23s interrupts the operating circuit of relay 234. Since relay 226 is now maintained in its marking position, the locking circuit through its spacing contacts for maintaining relay 234 operated will be interrupted. Consequently, a short interval of time later, relay 2 34 will release and remove ground from the upper terminal of condensers 2M and 248 which are now connected together due to the fact that relay 242 was previously operated and locked operated under the control of relay 231 as described above.

At station A the reception of the figures signal followed by the H signal cause contacts 124 to momentarily operate and interrupt the locking circuit of relay I39, thus permitting relay I39 to release. The'release of relay I39 interrupts the operating circuit of relay 52 3. Since relay I26 is now maintained in its marking position, the locking circuit of relay I34 which extends through the spacing contacts of relay I26 will be interrupted. Consequently, relay 834 will re- The release of relay H34 removes ground from the upper terminal of condenser 847. This terminal of condenser it! then starts to charge to a positive potential through the high resistance M5. 'It should be noted that relay M2 at station A has not been operated. Consequently, only condenser I' l! starts to charge since condenser M8 is not connected in parallel with condenser l i'i at this time.

At station C, the figures signal which was received at the end of the last message transmitted from the transmitter 253i causes the platen contacts i543 to close and remain closed so long as the platen remains in the upper case position. The following H signal causes contacts 45! to be operated and complete a circuit for the operation of relay 3l5, as described above. Relay 315, in operating, interrupts the locking circuit of relay M3 and permits this relay to release. The release of relay 3,!3 interrupts the operating circuit of relay M2. Inasmuch as relay SE is now maintained in its marking position the locking circuit of relay 3E2 extending through the spacing contacts of relay tlil is interrupted. Therefore, a short interval of time after relay 3E3 releases, relay 3 i2 will release.

Inasmuch as relay 1162 is also maintained in its marking position, ground will be removed from the upper terminal of condensers 344 and thus permit them to charge to a positive potential through the high resistance 345. It should be noted that since relay 3I3 is released condensers 343 are not connected in parallel with condensers 344. Consequently, only condensers 344 begin to charge. Thus ground is removed from the upper terminals of condensers 241, 248, I41 and 344 at substantially the same time and positive potential applied to the upper terminals of these condensers so that they all start to charge at substantially the same time. As pointed out above, the time constants of condenser 344 together with the charging resistance 345 are'such that it requires a longer time for them to charge sufii'cientlyto operate relay 3I8 than itdoes for condenser I41 to acquire a suificiently high positivepotential to cause relay I43 to operate. With condensers 241. and 248 connected in parallel, the constants of these condensers are so related to the charging resistance 245 that it requires a longer timeto charge these condensers sufliciently to operate relay 243 than is required to charge condensers I41through resistance I45.

. Under these conditions, relay I43 will operate first. The operation of relay I43 completes a circuit for the operation of relay I4I from battery through the winding of relay Hi, the left-hand break contacts of relays I42 and I31 to ground through the operated contacts of relay I43. The operation of relay I4I completes acircuit for maintaining itself operated under the control of the contacts of relay I43.

Assuming now that relay I36 has been previously operated due to the operation of key I3I and the insertion of tape I03 in transmitter IOI, as described above, the operation of relay I M completes a circuit for the operation of relay I38 similar to the circuit described above with reference to relay 238. V

Relay MI, in operating as described above, also completes a circuit for the operation of relay I42. Relay I42, in operating, connects condensers I48 in parallel with condensers I41. Inasmuch as condensers I48 are discharged at the time they are connected in parallel with con-' densers I41, the potential of the upper terminals of the combined condensers I41 and I48 will fall to a sufiiciently low value to cause relay I43 to release and thus interrupt the locking circuit of relay MI.

The operation of relay I38, as described above, completes a circuit for the operation of the start magnet I09 of transmitter IOI, thus releasing the brush arm I06 for rotation. The rotation of brush arm I06 causes the transmitter IM to transmit the, message recorded in tape I03 over the transmission system. Relay I26 will follow the signals transmitted from transmitter NH and upon the transmission of the first break impulse thearmature of this relay will move to its spacing position where it completes a circuit for the operation of relay I39. Relay I39 in operating completes a circuit for maintaining itself operated under control of relay I38. Relay I39 in operating also completes a circuit for the operation of relay I34. The operation of relay I34 connects ground to the upper terminals of condensers I41 and I48 thus discharging these condensers which in turn causesrelay I43 to release.- The release-of relay I43 causes the release of'relayI I-I. However, since relay I 38, inoperating, completes two locking circuits, one under the control of contacts I24 and the other under the control of relay I40, the release of relay I4I does not cause the release of relay I38. Neither does the release of relay I4I cause the release of relay I42 because v relay I42 is locked operated under the control of relay I31.

' Thereafter the circuits at this station remain in this condition during the transmission of the message from'station A.

When these messages arrive at station E, relay 226 will respond to them by moving its armature to its spacing position in accordance with the signals where a circuit is completed for the operation of relay 239. The operation of relay 239 completes a circuit for maintaining itself operated under the control of contacts 224 and also completes a circuit for operating relay 234. Relay 234, in operating; completes a circuit for maintaining itself operated under the control of the spacing contact of relay 226. The operation ofrrelay 234 also connects ground to the upper terminal of condensers 241 and 248, thus preventing the upper terminals of these condensers from being charged to a sufliciently high positive potential to cause relay 243 .to operate. Thereafter, during the transmission of messages from station A, the circuits at station B remain in the above conditions.

Relays I and 302 at station C also respond to and follow the signals transmitted by the transmitter II at station A. Relay 30I, in op- -erating to its spacing position in response to spacing impulses transmitted from station A, completes a circuit for the operation of relay 313. Relay 3I3', in operating, completes a circuit for maintaining itself operated under the control of relay 3I5. Relay 3I3, in operating, also completes a circuit for the operation of relay 3I2.

Relay 302 also responds to the signals transmitted from transmitter I9I at station A by moving its armature to its spacing position in response .to spacing impulses transmitted from station A. In its spacing position, relay 302 connects ground to the upper terminal of condenser 344, thus discharging condenser 344 and preventing the upper terminal of this condenser from acquiring a sufficiently high positive potential to cause relay 3I8 to operate during the continuous transmission of signals from station A.

Thereafter, the circuits atstation C remain in this condition during the transmission of the remainder of the message from station A. Following the transmission of each message a figures signal followed by an H signal are transmitted from station A. The circuits at station C respond to these signals in the same manner that they responded to the figures signal followed by the H signal transmitted from station B following each message, as described above.. The circuits at each station B respond to this figures signal followed by the H signal transmitted after or between each message in the same manner that the circuits at station A responded to these same signals when transmitted between these messages from station B, as described above.

Starting the control station If the supply of perforated tape I03 runs out of the transmitter IOI before the end of the transmission interval assigned to station A, contacts [I3 will open and interrupt the locking circuit of relay I30 which relay releases and interrupts both locking circuits of relay I38.

If the supply of perforated tape I03 does not run out before the end of the transmission time interval assigned to station A, relay I40 operates at the end of this time interval. Then at the end of the message in progress of transmission when relay I40 operates, the figures signal fol,

lowed by the H signal cause contacts I24 to momentarily open and interrupt the second and last locking circuit of relay I38, thus permitting this relay to release.

Relay I38 in releasing interrupts the circuits of the start magnet I69 which magnet will then release its armature I I and cause brush arm I06 to come to rest and stop transmission over the transmission circuit. Thereafter, the relays I26, 226, 30I and 302 will be maintained in their marking positions. The release of relay I 38 interrupts the locking circuit of relay I39 and permits this relay to release. The release of relay I39 interrupts the operating circuit of relay I34. Since relay I26 is now maintained in its marking position, relay I34 will release a short interval of time later and remove ground from the upper terminals of condensers I41 and I48 which are now connected in parallel because relay I42 is now operated as described above.

Similarly, at station E, contacts 224 are momentarily opened in response to the figures signal followed by the H signal. The momentary opening of contacts 224 interrupts the locking circuit of relay 230. The subsequent release of relay 233 interrupts the operating circuit of relay 234. Since relay 226 is then maintained in its marking position, relay 234 will release a short interval of time later and remove ground from the upper terminals of condensers 241 and 248, thus permitting the upper terminals of these condensers to acquire a positive potential through high resistance 245.

At station C, the figures signal followed by the H signal first cause contacts 450 to close and then contacts 45I and complete a circuit for the operation of relay 3 I 5. Relay 3 I interrupts the looking circuit of relay 313 and permits this relay to release. The release of relay 3I3 interrupts the operating circuit of relay 3 I2 which relay in turn releases because its locking circuit is interrupted at the spacing contacts of relay 302 which is maintained in its marking position at this time. With relay 302 maintained in its marking position, the upper terminals of condensers 344 will start to charge to a positive potential through the high resistance345. It should be noted that since relay 3I3 is released condensers 343 are not connected in parallel with condensers 344.

Here again, the charging of the condensers at the respective stations is initiated at substantially the same time by transmission of the figures signal followed by the H signal and the subsequent maintaining of the transmission system in its marking condition.

The time constants of the circuits at stations A, B and C under these conditions are such that condensers I41 and I48 when connected in parallel and condensers 24'! and 248 when connected in parallel will be charged to sufficiently high positive potential to cause the respective relays I43 and 243 to operate prior to the time the upper terminal of the condenser 344 is charged to a It is not ma- The operation of ing itself operated from battery through its winding and right-hand operated contacts to ground through the operated contacts of relaly I43. The operation of relay I31 interrupts the locking circuit of relay I42 thus permitting this relay to release.

The circuits at station A thereafter remain in this condition until signals are received over the A short interval of time after relays I43 and 243 have operated the upper terminal of condenser 344 will become charged to a sufficiently high positive potential to cause relay 3I8 to operate. Relay 3I8 in operating completes an obvious circuit for the operation of relay 3I9. Relay 3H! in operating completes a circuit for the operation of relay 463 from battery to the winding of relay 463 through the lower break contacts of relay 460, the break contacts of key 305, and the operated contacts of relay 3I9 to ground through the lower break contacts of relay 463.

Relay 453 in operating completes a circuit for maintaining itself operated from battery through its winding and the lower break contacts of 'relay 460 to ground through the lower inner operated contacts of relay 463.

Relay 463 in operating also completes a cir- Relay 323.: in operating completes a circuit for the operation cuit for the operation of relay 323.

of relay 3| 4 from battery through the Winding of relay 3I4 and lower operated contacts of re lay 323 to ground through the upper break contacts of relay 330. Relay 3I4 in operating completes a circuit for maintaining itself operated under control of relay 3I2. Relay 323 in operating completes a circuit for the operation of magnet 405. Magnet 405 in operating renders the tape advancing means of the transmitter 40I inoperative so that during the time magnet 405 is The manner in which the operation of magnet 405 prevents the advance of the tape maybe more readily understood by reference to Fig. 8"

which shows the manner in which this feature is applied to the tape controlled transmitter disfully included and set forth herein;

Magnet 805 of Fig. 8 corresponds to magnet 405 shown in Fig. 4. Magnet 805 in operating attracts its armature BI!) and rotates it in a counter-clockwise direction as shown ihFig, 8 so that its upper end will engage lug 028 on the feed paul 8I8 when it is lowered during the operation of the transmitter as described in the above identified patent to Watson. 7

When lug 828 engages member 8I9 when paul 8I8 is lowered paul BIB is rotated in a counterclockwise direction .so that it disengages the ratchet wheel 820 w he n lever BI! is rotated in a,

clockwise direction by plate 8 I 0.

Consequently, as long as magnet 305 is ope-rated its armature 8I9 engages lug 828 so'tape 803 will not be advanced when the sensing fingers 826 are withdrawn from tape 803. These'fingers therefore sense "the same row of perforations for every cycle of operation of the transmitter.

Returningnow to the operation of the circuits, relay 3 in operating also short-circuits the contacts of relay 303 and thus prevents relay 303 from repeating signals to the typing reperforator 402,.

Relay .323 in operating. completes a circuit for the operation of relay 450 when the transmitter brush arm 40B comes to rest. Normally transmitter brush arm 406 will be at rest at this time consequently relay .323 in operating will complete a circuit :for the operation of relay 459 from battery through the winding of relay 4013, the upper inner break contacts of relay 46I, the upper operated contacts of relay 32.3, the upper inner break contacts of relay .322, lower break contacts of relay 321, the upper break contacts of relay 3.35 to ground through the closed contacts'42i. Relay 450 in operating completes a circuit for operating the start magnet 409 from ground through the lower operated contacts of relay 459 the upper break contacts of relay 46!, the upper inner operated contacts of relay 323, tape controlled --contacts M4 and switch -4I2 to battery through the winding of magnet 409. The operation of start magnet 409 releases the brush arm 406 for rotation.

Near the beginning of this rotation contacts 42I open and remove ground from the left winding terminal of the winding 46L Relay 401 thereupon operates .in series with the locking circuit for relay 459 from battery through the winding and the lower inneroperated contacts of relay 459 and winding of relay 46I to ground through the lowermost operated contacts of relay 323. The operation of relay 46I at this time interrupts the operating circuit of the start magnet 408 thus insuring that the brush arm 406 will come to rest at the end of this revolution.

During this revolution of the brush arm 40B and transmitter 40!, relay 463 will .be operated as described above. Consequently the potentials applied to segments I to 5 of the distributor 401 are such as to cause this distributor to transmit a figures signal. This signal is represented in the usual code signal impulses comprising a marking 1st, 2nd, 4th and 5th impulses and a spacing third impulse. When these impulses are transmitted, together with the start and stop impulses to stations A andB they will cause relays I 30 and I34 at station A to operate and relays 2,39 and 234 at station 33 to operate. At station A the Operation of relay I34 connects ground to the upper terminal of condensers I47 1 and I48 thus discharges these condensers and interrupts the fiow of current through tube I44.

Relay I43 thereupon releases and interrupts the At the control station relay 30I follows the figures signal transmitted to stations A and B and completes acircuit for the operation of relay 3I3 which relay in operating completes a circuit for the operation of relay 3I2. Relay 302 also follows the signals transmitted at stations A and -B at this time and grounds the upper terminal of condenser 344 which in turn interrupts the flow of current through tube 324and causes relay 3I8 to release, which in turn causes relay 3I9 to release.

Near the end of the revolution of brush arm 406 during which this figures signal is trans mitted contacts 421 will again be operated or closed. The operation of contacts 42I at this time completes a circuit for the operation of relay 464 from battery through the winding of relay 454, the upper break contacts of relay 462, the upper inner operated contacts of relay 455i, the upper outer operated'contacts of relay 323, the upper inner break contacts of relay 322, lower break contacts of relay 321, the upper break contacts of relay 335 to ground through the operated contacts 42I.

The operation of relay 464 applies the necessary potentials to segments I to 5 of the distributor 401 so that during the next revolution brush arm 406 an H signal will be transmitted. That is, a signal combination in the usual code in which the first, second and fourth impulses are spacing, the third and fifth impulses are marking. The operation of relay 464 also completes a circuit for the operation of the start magnet 409 fromground through the innermost upper operated contacts of relay 464, lower break contact of relay 462, the upper inner operated contact of relay 323, tape controlled contacts M4 and switch 4I2 to battery through the winding of start magnet 409. The operation of start magnet 400 at this time releases the brush arm.

406 for rotation. Near the beginning of rotation of brush arm 406 contacts 42I open and remove a short circuit from around the winding of relay 462. Relay 432 thereupon operates in series with the locking circuit of relay 404 from battery through the winding and lower operated contacts of relay 464 and the winding of relay 462 to ground through the lower outer operated con tacts of relay 323. The operation of relay 462 interrupts the circuit of start magnet 409 and thus permits this magnet to release and stop the brush arm 40% at the completion of this revolution.

During the ensuing revolution of brush arm 406 an H signal will be transmitted by the transmitter 401 to stations A and B. A short inter-' ground from the upper terminal of condenser This terminal condenser I41 will there.-v

I 41. upon start to charge to a positive potential. Similarly the reception of the figures signal followed by the H signal at station B will cause contacts 224 of the selector 202 to operate and interrupt the locking circuit of relay 230 which relay in turn releases and interrupts the locking circuit of relay 234. At this time relay 225 is maintained in its marking position so that relay 234 will release and remove ground from the upper terminal of condenser 241. Thereupon condenser 241 will also start to charge to a positive potential.

However, under the assumed conditions with messages awaiting transmission from the main or control station C relays I34 and 234 may or may not release. If these relays do not release relays I39 and 239 will be operated. upon reception of the first carriage return signal of the succeeding message by the closure of contact I23 and 223 by the, selector mechanisms in response to the reception of this signal.

At the completion of the revolution during which the H signal is transmitted by brush arm 406, contacts 42| will again close and complete a circuit for the operation of relay 460 from battery through the winding of relay 460, the upper operated contacts of relays 462 and 46I, the upper outer operated contacts of relay 323, the upper inner break contacts of relay 322, lower break contacts of relay 321, the upper break contacts of relay 335 to ground through the closed contacts 42!. The operation of relay 460 at this time interrupts the locking circuit of relay 463 and permits this relay to release. The release of relay 463 interrupts the operating circuit of relay 323 which relay in turn releases and releases relays 450, 46I, 462, 460 and 464 and also magnet 405. The release of magnet 435 will permit tape 403 to be advanced through the transmitter in the normal manner when the transmitter is again operated.

Under the assumed conditions the operator had previously inserted a tape 403 in transmitter 40I and had operated the transmitter start key 306. Consequently when relay 460 operates as described above a circuit is completed for the operation of relay 330 from ground through the upper operated contacts of relay 460 and the lower operated contacts of relay 320 to battery through the Winding of relay 330. Relay 460 is sufliciently slow in releasing to provide time for'the operation of relay 330.

The operation of relay 330 completes the filament circuit of tube 329 and thus conditions this tube and its related circuits for operation. The operation of relay 330 also initiates the discharging and charging of any of the condensers 340, 34I or 342 which may be connected to the grid of tube 329 by the operation of the respective keys 331, 338 and 339.

The operation of relay 330 completes an obvious circuit for the operation of relay 3I4 if it is released at this time. Relay 3I4, in operating. prepares a circuit for maintaining itself operated under control of relay 3I2 when relay 3I2 operates, as described hereinafter. The operation of relay 3I4 short-circuits the contacts of repeating relay 303 so that the message transmitted from transmitter 40I will not be repeated to the typing reperforator.

The operation of relay 330 completes a circuit for maintaining itself operated from battery I through its winding, the lower inner break con-. tacts of relay 332, upper operated contacts of relay 330, to ground, through the tape controlled contacts 4I3 which are closed so long as there is a supply of tape 403 passing through transmitter 40I l The operation of relay 330 also completes a circuit for the operation of the start magnet 409 from battery through the winding of startmagnet 409, switch 4I2, tape controlledcontacts 4| 4, the upper break contacts of relay 323, left-hand lay 330, lower break contacts of relays 332 and 334, the right-hand contact and armature of relay 466, the lower inner break contacts of relay 332, the upper operated contacts of relay 330 to ground, through the tape controlled contacts 4 I 3. Start magnet 400 attracts its armature M0 and releases the brush arm 406 for rotation. Brusharm 406 in rotating causes the transmitter 40I to transmit the message stored in tape 403 over the transmission circuit.

As before, relays I26, 226, 30I and 302 all respond to the signals transmitted over the circuit;

inner break contacts of key 308, lower break con-I tacts of relay 3I1, upper operated contacts of re- In response to the spacing impulse transmitted from the transmitter 40I, relay 3M operates to its spacing position and completes a circuit for the operation of relay 3I3, if this relay is re.-'

leased at this time. Relay 3 I 3, in operating, completes a circuit for maintaining itself operated under the control of relay 3i 5 and completes a circuit for the operation of relay 3I2. Relay 3I2 completes a locking circuit for maintaining itself operated under control of relay 30I. In addition, relay 3I2 completes a circuit for maintaining relay 3I4 operated, as described above. This insures that none of the message transmitted from the transmitter 40I will be repeated back to the typing reperforator 402.

The operation of relay 302 to its spacing position connects ground to the upper terminals of condensers 344 and. 343, thus preventing these condensers from acquiring a sufliciently high positive potential to cause relay 3; to operate.

Similarly, at stations A and B, the operation of relays I26 and 226 to their spacing position is in response to the first spacing impulse transmitted from the transmitter 40I to cause the circuits at these stations to be conditioned, as described above when the transmission was from some other station of the system. The circuits at various stations are maintained in these conditions, as described above, during the transmission of the remainder of the message from the transmitter 40I at station C.

It should be noted that all of the messages transmitted from any of the stations are recorded at all of the stations of the system excepting that messages transmitted from the control station are not again recorded at the control station. Otherwise, all of the messages transmitted over this system are recorded at all of the stations connected to the transmission path.

Transmission from the control station The transmitter 40! then transmits the message stored in tape 403 to the transmission path extending to stations A and B. The message transmitted from station C are recorded by both A and B as described above. At station C, as at stations A and B, if none of the keys 331, 338 and 330 are operated relay 328 will operate immediately following the operation of relay 330. However, if one or more of the keys 331, 338 or 333 are operated the respective condensers 340, 34! and 342 will be discharged and then charged through the high resistance 346. The time constants of the charging circuit of these condensers are .of the same order as described with reference to condensers 256, 251 and 258 and I56, I51 and .Assume that the first message recorded in. tape 403 is completely transmitted before the end of this time interval and that other messages are recorded in tape 463.

So long as relay 325 remains released relay 465 is maintained in its left-hand position by current flowing from ground through thebreak' contact of relay 326 through the lower winding of relay 465 to battery. Consequentlyrelay 365 will not respond to the figures signal transmitted by the transmitter 43 at the end of the first message, neither will relay 466 respond to the following 1-1 signal. Relay 465 is maintained in the position shown .in the drawings by current flowing from battery to its upper winding to ground through the lower break contact of relay 33 l When this figures signal followed by the H signal is received at stations B andC they respond as described above when the message is transmitted over the system from some station other than the respective stations A and B to these stations A andB.

This mode of operation is repeated during and between the transmissions of each of the messages recorded in tape 433 so long as relay 325 does not operate.

Assume now that the time interval allotted to station 'Chas elapsed and that at the end of this interval relay 328 operates. The operation of relay 323 applies a positive potential to the lower terminals of any of the condensers 341, 342 and 343 that may be connected to the grid of tube 329. This causes a sudden increase in the potential of the grid of tube 329 thus increasing the current flowingthrough relay 328 and makes its operation at this time more positive. The operation of relay 328 completes an obvious circuit for the operation of relay 336. Relay 325 interrupts the circuit traced above through the lower winding of relay 435. The armature of relay 465 is then controlled by the currents flowing through the windings of relay 465 in accordance with position of the contacts Ito 5 of the tape transmitter 461. The position of the contacts I to 5 are controlled by the pertonations in the tape 403 and assume the various positions in accordance with the permutation code signals recorded in tape 463 and transmitted by distributor 437 of transmitter 49!. The windings of relay 435 are so connected to battery and ground and the'contacts l to 5 through suitable resistances so that relay 465 will have current flowing through its windings in such a direction as to maintain its armature in its right-hand position for all settings of the contacts I to 5 except the code combination representing the figures signal. When the figures signal following the message, which was being transmitted at the time relay 325 operates, arrives over the sensing pins and sets contacts I to 5 in the combination representing the figures signal the current through both windings of relay 465 fails to substantially zero because battery is applied to both terminals of the lower winding and ground to both the terminals of the upper winding. With substantially no current flowing through the windings of this relay its armature will move to its left-hand position under the infiuence of a biasing spring where it completes a circuitfor the operation of relay 335 from battery through the winding of relay 335, the left-hand 1 contact and armature of relay 465, the lower inner break contact of relay 332, an upper oper-,

ated cont-act of relay 330 to ground through the tape controlled contacts M3. Relay 335 in operating completes a circuitfor maintaining itself operated from. battery through its winding, the lower break contacts of relay 336, lower outer operated contacts of relay 335,.1o-wer inner break contacts of relay 332 and upper operated contacts of relay 333 to ground through thetape controlled is still in the transmitter 43| so contacts 4|3 will be closed at this time.

At the completion of the revolution of the brush arm 436 during which the figures signal was transmitted, cam 42!) caused contacts 42! to close to a circuit for the operation of relay 33'l. Relay 33! in operating interrupts the circuit through the upper winding of relay 463 as described above so that relay 466 is then controlled by the currents flowing through both of its windings under the control of the setting of contacts to 5 of transmitter 40!. 'As the transmitter brush arm 406 starts the next revolution for the transmission of the signal recorded in tape 403 contacts 42! will open and cause relay 333 to operate in the circuit from battery through the winding of relay 33L the operated contacts of relay 331, the winding of relay 333, the lower operated contacts of relay 335 through the righthand contact and armature of relay 465, lower inner break contacts Of relay 332 and upper operated contacts of relay 330 to ground through contacts 4I3. If the next signal recorded in tape 433 is a figures signal relay 465 will again operate and interrupt the locking circuit of relays 33! and 333. If this is the case, the above cycle of operation will then be repeated when brush arm 4% nears the completion of the revolution during which the second figures signal is transmitted, contacts with 42! will again close and complete a circuit for the operation of relay 33!. The operation of relay 33| again prepares a circuit for the operation of relay 333. Relay 333 howtact and armature of relay 466, lower inner break contacts of relay 332 and upper operated contacts of relay 330 to ground through the tape controlled contacts 4] 3.

If any combination other than an H signal or another figures signal isa perforated in the tape 433 following the figures signal, relay 466 will not operate so relay 334 will not operate at this time. Consequently if. any cod combination other than a figures signal or an H signal is recorded in tape 463 following the figures signal, contacts 42l, when they close near the endof the transmission of this signal following the figures signal, a circuit will be completed for the operation of relay 336 from ground through contacts 62!, the upper operated contacts of relay 335, the operated contacts of relay 333, the upper unoperated contacts of rela 334 and the winding of relay 336 to battery. The operation of relay 336 at this time interrupts the looking circuit of relay 335 which relay releases and,

in'turn interrupts the locking circuit of relays 33| and 333 thus canceling the eiTe-ct of the figures signal.

If, however, the H signal immediately follows the figures signal relay 334 operates as described above aridlocks operated in a circuit extendin from battery through itswinding and lower inner operated contacts, the break contacts of relay 336, lower'outer operated contacts of relay.

335, lower inner break contacts of relay 332 and tem relay 302 above.

upper operated contacts of relay 330 to ground through closed contacts 413.

The operation of relay 334 interrupts the circuit of the start magnet 409 consequently the brush arm 406 will come to rest at the completion of the revolution during which the H signal was transmitted. Near the completion of this revolution of brush arm 406, cam 420 will again close contacts 421 and complete a circuit for the operation of relay 332 from battery through the winding of relay 332, the upper operated contacts of relays 334, 333 and 335 to ground through the operated contacts 421.

Relay 332 in operating interrupts the locking circuit of relay 330 and also of relays SP and 334 which relays release and in turn interrupt the locking circuit of relays 331 and 333 which relays then release. The release of relay 330 interrupts the locking circuit of relay 332 and permits this relay to release.

The release of relay 330 interrupts the filament circuit of-tube 329 and removes ground from the lower terminals of condensers 340, 341 and 342 and connects ground to the upper terminals of these condensers thus restoring the timing circuit comprising these condensers, tube 329 and resistance 346 to normal. Relay 330 in releasing also interrupts the operating circuit of the start magnet 409 of transmitter 401 and thus insures a transmitter will not restart when relay 332 releases.

The release of relay 330 completes a circuit for the operation of relay 315 from battery through the winding of relay 315, the right-hand operated contacts of relay 314, lower break contacts of relay 323 to ground through the upper outer break contacts of relay 330. Relay 315 in operating interrupts the locking circuit of relay 313 q and permits this relay to release. The release of relay 313 interrupts the locking circuit of relay, Inasmuch as transmitter 401 remains at rest as do all the other transmitters connected to the circuit, relay 301 will be maintained in its right-hand position where it interrupts the operating circuit of relay 312 thus permitting relay 312 to release. The release of relay 312 interrupts the locking circuit of relay 3E4 thus relay to release. Inasmuch as being transmitted over this sysis also maintained in its righthand position consequently the upper terminals of condensers 344 will start to receive a charge through'the high resistance 345.

When the figures signal followed by the H signal at the end of the last message transmitpermitting this no signals are ted by the transmitter 401 is received at stations A and Bit will cause relays 139 and 134 at station A to release and relays 239 and 234 at station 13 to release. The upper terminalsof condensers 14'! at station A and 241 at station B will then start to receive a positive charge. The circuit is now in the same condit on as assumed at the beginning of the description. If all of the stations still have message matenal for transmission and tape perforated in accordance with this material and has been inserted in the transmitters and the respective transmitter start keys operated the system will operate as described perforated tape 433 runs out of the u 1 V If S pp y the end of the time the transmitter 401 prior to interval assigned to station C, contacts 413'will open shortly after the transmission of figures and H signals following the transmiss on of the final message stored in tape 403. The opening 'of contacts 413 at this time interrupts the'circuit of the start magnet 409 and. thus stops the operation of transmitter brush arm 406. The opening of contacts 413 also interrupts the looking circuit of relay 330 which relay releases and restores the circuit to its initial condition as described above. There will be no carriage return signal perforated in the tape 403 following the figures and H signals perforated in tape 403 at the end of the last message stored in this Consequently, relay 139 at station A, relay 239 at station B and relay 313 at station C will not be reoperated. Consequently, the timing circuits at these stations will operate as described above.

Assume now that none of the stations have any message material to transmit. Consequently, the end of approximately one second relay 243 will operate and completea circuit for the operation of relay 241. Relay 241 in turn will operate and complete a circuit for operating relay 242 which relay completes a circuit for maintaining itself operated under control of relay Since there is no message material awaiting transmission at station B relay 236 will not be operated. Consequently, the operation of relay 241 will not cause the operation of relay 238. No transmission will therefore be started from the transmitter 201 at station B. The operation of relay 242 at station B connects the discharged condenser 248 in parallel with condenser 241 and thus interrupts the flow of current to tube 244 as described above which, in turn, causes relay 243 to release and in turn release relay 241. Thereafter condensers .241 and 248 will continue to be charged. However, 'as pointed I out above it will require approximately at least 4 seconds addition of time-for the upper terminals of these condensers to require sufficiently high positive potential to ,cause relay 242 to again operate.

Meantime, condensers 147 have been charging so that at the end of approximately 3 seconds from the time of the transmission signal of the H signal following the last message relay 143 will operate and complete a circuit for the operatio of relay 141. Relay 141 in operating completes a circuit for the operation of relay 142 which relay in turn operates and completes a circuit for maintaining itself operated.

Since no message material is awaiting transmission from station A relay 138 will not be operated by the operation of relay 141 because relay 136 was not previously operated.

Even if tape 103 had been inserted in transmitter 101 and the transmitter start key 131 operated during the time relay 141 was operated but after relay 141 operated, still transmission will not start from transmitter 101 because it is necessary to operate the key 131 and thus relay 136 prior to the operation of relay 141 because the operating circuit forrelay 136 is interrupted by the break contacts of relay 141 when relay 141 is operated. The operation of key 131 during the time relay- 141 is operated but after relay I41'has operated establishes an obvious circuit for the operation-'of'relay 135. Relay 135 when operated completes a'circuit for maintaining itself operated under the control of contacts 113 which will be closed if tape is inserted inre'p'eater 101. Consequently when relay 141 later releases relay 136'wi1l then be operated The circuit for the operation of relay 136 at lease. main in this condition until signals are received tube I34 is interrupted and relay I43 released.-

The release of relay I43 at this time interrupts the locking circuit of relay HI and permits this relay to release; Thereafter condensers I4! and I48 continue to be charged to a positive potential. As described before; the parallel combination of condensers I41 and I48 and the parallel combination of condensers 241 and 248 receive a sufiicient positive charge to cause relays I43 1 and 243 to operate at about the same time time interval is of the order of '5 seoonds'from the time of the transmission of the last figures signal followed by the H signal "as described above. The operation of relay I43 at this'time completes a circuit for the operation of relay I31 which relay in turn interrupts the locking circuit of relay I42 and permits this relay "to re- Thereafter the circuits at station A reover the transmission loop. Similarly, the operation of relay 243 at station B. completes a circuit for the operation of relay 231 which relay in turn interrupts the locking circuit of relay 242 which releases. Thereafter the circuits at station B remain in this condition until signals w are received over the transmission loop.

Approximately 2 seconds after relays I43 and 2 33 operate relay"3I8-will again operate and toperate relay 3I9; -Relay 3'l9 completes a circuit for the operation of relay "463 as described above and the above-described cycle of operations repeated during which a figures signal followed by anH signal is'transmitted over the transmissiOIi path" extending'to stations -A and B. "The figures signal followed by the H signal will first cause relays I39, 239 and 3I'3 at their respective stations tobe operatedand then later released as described above. Theoperation of these relays and their subsequent. release discharges the condensers I 41 and 241 at their respective stations A and B. The figures' signal followed by the H signal also causes condenser 344 at station C t'o'be discharged after which the above cycle of operations was repeated. If in the meantime'a'ny attendant at any of the stations has inserted a tape in the transmitter and has operatedth'e transmitter start key signals stored in that tape will be transmittedand then the above cycles of operation will be repeated.

, Bre'alc'siynals At any time an operator at any of the stations may transmit a break signal over the system and seize control of the transmission circuit. The break signal when transmitted over this system during the transmission from any of the stations causes the transmitter then transmitting to stop. Assume for example that transmissionis fromtransmitter 29 I ;at station l3 and that the operator at station Awishesto interrupt this transmission and seize control-of the transmission path. In order to accomplish this the operator at station A willoperate the break v key I2I.and hold it operated for a shortinterval of time; L'Ihepperation of key I2I causes a.- -'I5 at station B; under these conditions cannot be break signal to 'be transmitted over the transmission path. Consequently all of the line relays will remain in their spacing positions during the time key I2I is held operated. The receiving instruments at each of the stations A and B will respond to this break signal and cause member H8 at station A to actuate contacts H6 and II'!. 'At station 3 the member 2I8 will be actuated by the receiving device 202, and cause contacts 2| 1 and 2? to be actuated.

The manner in which these contacts are actuated is clearly described in the above identified patent to Morton et a1. patent with reference to the so-called send-receiv'e-break mechanism. The operation of the contacts 2I6 at stationB interrupts the circuit of the start magnet 209 thus permitting this magnet to release and stop the transmission from transmitter ZIII.

At station E relay 226 responds to the break signal by remaining in its spacing position 's'ufliciently long to permit relay 2 2'! to release. The release of relay 227 completes a circuit for the operation of relay 232 from battery through the winding of relay 232; break contacts of relay 227, right-hand outer operated contacts of relay 236 and left-hand opera-ted contacts of relay 238 to ground through contacts 224. The operation of relay 232 completes a circuit for maintaining itself operated under control of the release key 229. The operation of relay 232 also completes a circuit for the operation of relay 233. Relay 233 in operating also interrupts the operating circuit of the start magnet 269 thus insuring that the transmitter 20I will not restart upon the operator restoring contacts 2I6 and 2'II to the position shown in the drawings. The re- .lease of relay 22'! also lights the lamp 228 to key, the equipment at these other stations operates in a similar manner to stop the transmitter and indicate to the operator that another operator wishes to seize control of the circuitor that some trouble condition exists on the circuit.

It should be noted that the transmitter 'ZIJI restarted until'key 229 is operated which in turn releases relays 232 and 233 and extinguishes lamp 228.

After the operator at station A has operated the break key I2I she may then restore contacts H6 and Ill to the positions shown in the drawings and thereafter communicate over the circuit with the other stations connected to the transmission path.

If the operator had operated'key'Z ZI at a time when no signals were being transmitted 'over the systemrelays I39 and I34 at station A and relays 23 9 and 234 at station B will operate as described above and stop the operation of the time circuits at these stations. Similarly relay 332 at station C will be operated during the transmission of the break signal and stop the charging of condenser 344 and thus arresting the action of vthe timing circuitlat this station. At the completion of the transmission by the operator who seized control ofthe circuit or any other operator transmitting thereafter, the last operator to transmit may-transmit aingu'res vtained in its marking position.

signal followed by an H signal. The circuits at the various stations respond to these signals as described above. If no figures signal and a following H signal are transmitted by the last operator to transmit over the system condensers 344 and 343 will start to charge-to a positive potential in parallel. After an appreciable period of time, of the order of about 30 seconds, relay 318 will operate in turn operate relay 319. Relay 319 in operating causes a figures signal followed by an H signal to be transmitted over this system. The transmission of these signals initiates the operation of the timing circuits at the respective stations whereupon they are each given an opportunity to transmit in turn as it has been recorded in tapes at the respective stations and the transmitter starts to operate as described above.

In order for the operator at the control station C to seize control of the circuit and transmit from her keyboard 455 it is necessary for her to first operate the locking key 308 to its operated position. The operation of key 368 removes a short circuit from around the keyboard controlled transmitting contacts 451 and thus permits these contacts to transmit over the transmission path. The operation of key 358 also connects ground to the upper terminals of condensers 344 and 343 since they will normally be connected in parallel during the time transmission is taking place over this system. The operation of a key 368 also interrupts the circuit of start magnet 499 of transmitter 43! thus preventing the transmission from tape bytransmitter 40!. rupts the locking circuit of relays 316 and 31! and thus extinguishes the line lamp 311 had it been lighted due to the fact that the transmission .had been from station C when the operator or attendant at station C or at some other station seized control of the transmission path.

Timing out If at any time during the time assigned for transmission from any station the transmission system remains in its marking condition for a prolonged interval of time indicating the trouble condition upon the circuit or at the transmitting station,the armature of relay 382 will be main- This will permit the upper terminals of condensers 343 and 344, which are connected in parallel, to be charged to a positive potential through high resistance 345. If this condition continues to exist for a period determined by the time constant of these circuits, which may be of the order of 30 seconds or more, the upper terminals of these condensers will be charged to a sufficiently high positive potential to cause tub 324 to pass sufficient current to operate relay 31B. Relay 318 establishes a circuit for the operation of relay 313. The operation of relay 319 completes a circuit for the operation of relay 4'63 which relay thereupon operates and causes a figures signal followed by an H signal to be transmitted over the circuit. These signals when received at the station conditioned for. transmission cause the operated relays to be released and initiate the operation of the timing circuits at all of the stations so that the transmission will be started from the other stations of the system provided they have any message material for transmission. Thus an operator can not maintain the control of the system indefinitely by merely holding the circuit in a marking con- The operation of key 398 also interious stations.

dition by causing the tape controlled contacts at any of the outlying stations to operate or by fail ing to transmit or perforate a figures signal followed by an H signal.

This timing out feature is also employed in case hits or interfering currents or signals are encountered during the time no signals are transmitted over the system and the time delay apparatus is in operation. The effect of hits, i. e., interfering currents and signals is to stop the action of the timing circuits at each of the'var- In order to again initiate the operation of these timing circuits it is necessary to send another figures signal followed by an H signal over the system.

When the interfering currents or signals are received at stations A and B, when no signals are being transmitted over the system and the timing circuits at the various stations are in operation, they cause relays 139 and 1 34 at station A and relays 239 and 234 at station B to operate and complete circuits for maintaining themselves operated. The operation of these relays restores their timing circuits to theirnormal condition.

When interfering currents are received at the control station during these times they cause relays 313 and 312 to operate and complete circuits for maintaining themselves operated. Thereafter when no further signals are received over the system. for the specified period the .above described timing out action is repeated 7 and a figures signal followed by an H signal is transmitted over the system which signals initiate the operation of the respective timing circuits as described above.

Automatic perforation of tape t may be desirale to cause the printing reperforator 402 to automatically perforate a supply of tape to permit the end of the last message recorded in the tape 493 to be readily removed from the machine. To accomplish this key 305 is provided. The operator will operate key 305 if she wishes the tape to be perforated. If trans- .mission is taking place over the system from station C at this time relay 314 will be operated, consequently the selector magnet 453 of the reperforator 492 will be maintained in its marking positionso letters signals will be perforatedin the tape. .Theoperation of key 365 under these 1421;; 330 to battery through the feed-cut magnet The manner in which magnet 452 causes the printing reperforator to automatically feed out and perforate an additional supply of tape may be more fully understood by reference to Figs. 6 and 7. Here magnet 652 corresponds to magnet 452 of the printing reperforator 462 shown in Fig. 4-. In addition the printing magnet 453, Fig. 5, is illustrated by magnet 653 in Figs. 6 and '7. The printing or selecting magnet 653 controls the selecting equipment in the usual manner as is Well understood and described in the above-identified patents to Morton et al.

The code combinations are set up on the; code bars 618 in the usual manner to select one of the pull bars 801 which is then actuated by the pull bar bail 662 to print the desired character on the V tape.

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