US2455724A - Control of selectors over communication channels by storage controlled transmitters - Google Patents

Description

0 Dec. 7, 1948. w. M. BACON' 2,455,724

CONTROL OF SELECTORS OVER COMMUNICATION CHANNELS BY STORAGE CONTROLLED TRANSMITTERS Original Filed Aug. 17,1940 2 Sheets-Sheet 1 Gigi A TTO RNE V Dec 7, 1943. T w M; BACON 2,455,724

CONTROL OF SELECTOR S OVER COMMUNICATION CHANNELS BY STORAGE CONTROLLED TRANSMITTERS Original Filed Aug. 17, 1940 2 Sheets-Sheet 2 4 me use.

POLA R/ZED Fu l INVENTOR W M BACON O v I -AT ORNEK- Patented Dec. 7, 1948 CATION CHANNELS BY STORAGE CON TROLLED TRANSMITTERS a Walter M. Bacon, New York, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N; Y a corporation of New York Originalapplication August, 1940, Serial No.

353,086; Divided and this application February 5, 1943, Serial No. 474,843

This invention relates to communication systems and particularly to telegraph systems wherein a plurality of stations on a common channel may set up connections betweeneach other and exclusively appropriate the channel to their own use. p d

The invention hereinafter claimed is disclosed but not claimed in Patent No. 2,320,997,flgranted June 8, 1943, to W. M. Bacon which resulted from copending application Serial No. 353,086, filed August 17, 1940,.as a continuation in part of an application, Serial No.. 290 ,'743, filed August 18, 1939. The present application is a division of the application which resulted in patent 2,320,- 997.

An object of the invention is to provide automatic means for preventing unnecessary operation of stations on a party line when such stations are not involved in a connection. .In particular it is an object of the invention to prevent unnecessary operation of the motors of a plurality of teletypewriters connectedto the partylines.

Another object of the invention. is to provide for the selective setting up of connections between any two or more stations under the control of signals stored in andgenerated by a storage type of transmitter. i

In accordance with this invention and as a specific illustration of how the invention may be applied, a communication channel is provided to serve a plurality t stations eachequipped with a teletypewriter. A station circuit is provided with means for sending out over the channel a prolonged signal of predetermined length for the purpose of callingtin the other stations on the channel. By calling in is meant to -change all the other stations from theirnormal nonoperative condition to an operative condition in which they are able to respond to the type oisignal ordinarily used fortheir regular operation. Specifically, a time controlled switch is provided ateach station for sending out over the common channel a spacing signal {where the normal condition of the channel is marking) of the order of four seconds duration. Each other stationon the channel will respond to. such a signal by starting the teletypewriter motor thereat so that the mechanism of theteletypewriter will properly respond to permutation code signals. Thereafter the calling stations may putlselected ones of said other stations onwhat may be termed apermanent operativebasis, thatis, such selected stations are now placed beyond interference by any fur- .ther operation at the callingstation exceptingof course, the releasingoperation. Thereafter the i 18 Claims. (Cl. 178 -2) i on a permanent operative basis.

calling station may release thosestations which have not been placed on a permanent operative basis and by so doing causethem to be locked out of the system andrendered incapable of interfering with the proper operation thereof. In one embodiment of the invention any one of the stations partyto an established connection may be selectively disconnected and such station will thereafter be locked out and rendered incapable of interference with the established connection. A locked-out station may be recalled and made a party to an established connectionthrough operations carried out at any one of thestations party to such establishedconnection. Each teletypewriter forming part of the circuit of the various stations is suppliedwith a number of contact sets operated by the teletypewriter mechanism and in response to various and particular codes. After the stations have been put on a temporary operative basis by slow-acting or timingmeans, individual stations or a group of stations are puton a permanent basis by the operation of certain contact sets by codes individual tosuch stations or individual to a particular groupof such stations. Any particular station may be equippedwith contact sets for individual callingonly or for group calling only or forboth. Still other contact sets may be provided for individual disconnect or group disconnect.

At the calling station means are provided for automatically placing such station on a permanent rather than a temporary operative basis. This means that thecalling subscriber need only transmit the code for the particular wanted station or stations and need not transmit the code for his own station. 1

Anyone or more of the stations on such a party line may be provided with tape transmitters. When thecalling is started from an idle condition the operation is the same as though'zthe transmission were tobe from an operators keyboard. However, a series of messages to different by a common code combination which will operate a special. contact set in the teletypewriter at all stations which are so equipped and care then This will operate a slow-acting meanswhich will not only send a prolonged calling-in signal over the line .to returntheselected stations not provided withua tape transmitter to normal andto unlock the non-selected stations, butwill at thesame time delay the further operation of the tape transmitter at the calling or transmitting station. This common code is then repeated to place all the other stations in a temporarily receptive condition so that by the further transmission from the punched tape certain selected stations may be placed on a permanent operative basis and the others locked out. Thus the code combinations for setting up a plurality of connections as well as the message for each such connection may be punched in the tape and the sequential operation of setting up a connection, transmitting the message, releasing the connection, setting up anew connection, etc., will be carried out automatically.

Any one of the parties to the established connection may transmit and all will receive such transmitted messages.

Any one of the parties to the establishedconnection may break down such connection and restore the channel tonormal Where it may be used by all the subscribers thereon.

Other objects of the invention and features will appear as the description proceeds.

The drawings consist of two sheets each containing a circuit diagram and each illustrating a difierent form of the invention.

Fig. 1 is a circuit diagram showing a telegraph line I extending through a station represented by a rectangle 3, and a station represented by the circuit-diagram of the main part of Fig. l. The station 3 may be the same as the station shown in detail in Fig. 1 or may differ from it by being without tape transmitter facilities and supplementary control mechanism pertaining thereto as will be described later. The line I may extend through and serve other stations some of which may have tape transmitter facilities and others of which may not have tape transmitter facilities as desired. It will be understood that a suitable source of current and a return circuit are provided for the telegraph line and that the normal condition is a closed circuit with current flowing in the line whereby the line relay 4 and the teletypewriter line relay or selector magnet of each station are normally held to their marking contacts. Relay 4 is a neutral type relay, that is, it is biased so that when no current flows through its windings, it moves its armature to the spacing contact. It should be noted that relays 4 and 5 may be polarized relays in case polarized signals are transmitted over line I. In case so-called neutral signals, that is, signals of current and no-current are transmitted over line I, relays 4 and 5 maybe neutral relays or they may be polarized relays provided with a biasing winding and current so that they will respond to'signal impulses of current and no-current.

It is also within the scope of this invention to provide any suitable type of telegraph channel between the respective stations. This channel may include a full metallic and ground return telegraph line, a channel of the carrier telegraph system, a channel of a radio communication system, a telegraph channel of a composited telephone and telegraph line and may include both cable and open-wire telegraph lines, as well as full duplex telegraph systems or a channel of a multiplex telegraph system or any operable combination of these systems. The only essential is that at each of these stations the system responds to two signaling conditions of the line and that the communication system transmits to each station signals to which the two relays will respond.

When the operator at the station shown in detail in Fig. 1 wishes to call in some other station, he operates the time-controlled switch 6. This will open the line circuit for a period of four seconds and at the same time will cause the I operation of relays l and [2. Relay 4 will move to its spacing contact, thereby energizing relay 8. Relay 8 is slow operating and is adjusted to move its armature only after being continuously energized for three seconds. Since the timecontrolled switch causes the relay 4 to go to its spacing contact for four seconds, relay 8 will become energized.

Relay 8 controls a pair of relays 9 and I I which constitute a pair of counting relays well known in the art. These relays operate in one complete cycle for each two complete cycles of operation of relay 8. Thus, upon the first energization of relay 8, relay 9 becomes operated. When relay 8 becomes released at some later time, relay ll becomes energized. When, subsequently, relay 8 again operates, relay 9 releases and when relay 8 again releases, relay ll releases.

Relay 9, therefore, now becomes operated and through its lower armature causes busy lamp Hi to light. Through this same connection a ground is placed on the inner armature of relay 1 to hold relays 1 and I2 locked.

During the operation of the time-controlled switch 6, relay I2 is operated and through its left-hand armature energizes relay [3 for closing the circuit of the teletypewriter motor 14 whereupon this motor starts into operation.

At the end of four seconds, the time-controlled switch 5 again closes through the line and the relays 4 and 5 of the calling station as well as all the other stations on the circuit go to their marking contacts. The lower contact of the switch 6, which originally caused the energization of relay 7, is also opened but through the locking contact of relay 1 a ground is extended to the winding of relay l2 so that this relay is maintained operated. As relay 4 moves to its marking contact, relay 8 is immediately released, with the result that relay ll becomes operated. Relay ll now establishes an alternate locking circuit for relays l and I2 through its lower outer armature.

If no other action is taken by the operator at this station, the circuit will now remain in the condition just described with motor l4 running and this condition would remain fixed indefinitely.

At all other stations on the line, such as the station represented by the rectangle 3, the movement of the line relay 4 to its spacing contact in response to the operation of the time-controlled switch 6 at the station making the call will result in the energization of relay 8 after the relay 4 has maintained its armature on its spacing contact for three seconds. Thereupon the relay 9 will become operated and cause the busy lamp IE to light. Thus, the busy lamps at all stations on the line become lighted. At these other stations relays 1 and I2 are not operated at this .time. At the end of four seconds, the relay 8 at each of the stations releases, whereupon the relay ll at such stations operates. Thereupon a circuit is established from ground, the contact and lower armature of relay 9, the inner lower armature and front contact of relay H, the normal contacts of the left-hand armature of relay [2, the right-hand armature and back contact of relay ll, winding of relay 13 to battery. Relay 13 becomes immediately energized and starts the motor M at each of these :stations into operation. Thus the motors areenow in operation at all stations. i I

Thereafter the operator at the callingstation may operate his transmitting contacts ill to transmit the code for Figures,=in response to which the contacts ill at each station will be operated. Contacts l9 are controlled by or with the platen member or other shift mechanism of the receiving device and are closed in response to the reception of a figures shift signal by the device. Contacts is when operated are closed so long as the device remains in the upper case.

These contacts are opened by sending anunshift or letters shift signal which returnsthe mechanism to the lower case.

The other contacts 20, 2| and 22 are actuated only momentarily inre sponse to the reception of the predesignated code combinations. These contacts close once for a short interval of time in response to the reception of each of the respective code combinations. Forexample, every time the Activate oodeoombination is transmitted contacts 20 will momentarily close. The manner in which pairs of contacts such as I9, 20, 2| and 22 are operated is illustratedin Patent 2,120,235, granted to James F. Beattie et al. June 14, 1938. If the calling operator again operates the transmitting contacts Hi to transmit a given code which will result in the operation of contacts 20, a circuit is established through contacts l9 and contacts 20 to the windingof relay23. Relay 23will operate and look through its left hand armature directly to the contacts l9 which remain closed until the code for Letters or Space is sent. All stations on the line thus have their relay 23 operated. This results in the operation of relay Hand relay 24 looks to the lower armature of relay The operation of relay 24 prepares an energizing circuit for the relay". f 1

The operator at the calling station now transmits another code which may be one arranged to operate the individual can contacts 2| of some particular station on theline, or it may bearranged to operate the group callingcontacts of two or more particular stations, on the line. There, of course, maybe severalsuch group calling contacts for calling difierent combinations of stations, as indicated by the multiple conductors. In addition, the operator may transmit several of these calling code combinations each of which operates the individual contacts at different stations or each of which operates different group contacts at different groups of stations. Let it be assumed that thecontacts 2| at the called station are closed. Thereupon a circuit is established from ground, right-hand armature and front contact of relay23, contacts 2|, windings of relays 1 and I2, in parallel, tobattery, Relay |2 thereupon substitutes an energizing circuit for relay I3 and opens the original circuit, from ground through the lower armature and front contact of relay 9 and inner lower armature and front contact of relay l l. Relay l2 locks up through its outer right-hand armature toj the groundon the lower armature of relay Thus, at the station or stations which have been called, the relay I2 is operated and such station orl stations are put on permanent operative basis. Upon the operation of relay' l2 a circuit is established through the inner right-hand armature of relay I2. thecall bell25, through-the "right-handfarmature and back contact of relay 26 to groundat the front contact and righthand armature of relay 23. The operation of bell 25 notifies the attendant at the called station thatflhis station is beingcalled. He may stop the operation of this hell by momentarily depressing the key 21, which will cause the op' eration of relay26 and which looks through its left-hand armature in order to maintain the circuit through its right-handarmature open.

The code for Letters or Space will now be sentto shut down the uncalled stations. This operation will cause the opening of the contacts l9 at all stations and the consequent release "of relay 23-. The release of relay 23 at the called stations interrupts the circuit of bell 25 and relay 26 and thus stops the operation of hell 25 if the attendanthas not previously operated key 21. If the attendant has previously "operated key21, the release of relay 23 will release relay 26. The release of relay 23 at the called station also disconnects-ground from the contacts 2| and 22st; that the subsequent operation of these contacts during the transmission of the following message will produce noeffect-s upon the switching circuits or connections at anyof the stations of the system.

each of the stations to record the message transmitted from the transmitting station. Relay 4 at each of these stations alsoresponds to the signalsiransmittedover line I. However, during I the normal transmission of signals over line I, relay 4 will not continuously remain in a spacing position for three seconds. Consequently, relay 3 will not operate at any of the stations and thus will not interfere with the established connec- Atthe uncalled stations since relay 8 does not operate, the counting relays Band ll remainoperated and relay 24 will be maintained locked operated. Therefore, a circuitis established from ground, the right-hand armatureand back contact of relay 23, the left-hand armature and front contact of relay 24, the winding of relay [1 to battery through the back contact and, inner right-handarmatureof relay l2, resulting in the energization of relay H which in turn opens the oircuitof relay l3, Relay l3 releases and interruptsthe operating circuit of motor M whereby the motorstops at eachjof. the uncalled stations.

Relayl'l also establishes a shunting connection through the resistance 21 about the keyboard transmitting contacts [8, the teletypewriter line relay 5,the tape controlled transmitting contacts 109 and the time-controlled switch 6 at all sta .tions which are not calledorwanted in this .con- 'nection;

Thus, at such stations the teletypewriterisshut down," interference with the estab lished connection is prevented, reproduction of the transmission at such stations is prevented and the relays 9, I! and 24 thereat are maintained operated. The line relay {at such stations willtoperate in accordance with the code signals, buttthe relay}; being arranged, to respond only after being"continuously energized for three seconds, will not operate. Interference withfanes- "tabllshedconnection by a locked out station is 7 prevented by a ground connection for the lower element of time controlled switch 6 through a back contact on relay I'I. Since this relay is operated at all looked out stations the operation of switch at, those stations will be inefiective.

At the end of the period of use any one of the stations effectively on the circuit may release the connection by operating its time-controlled switch 6 so as to cause the relay l at all stations to rest on its spacing contact for an equal length of time, that is, four seconds. Thereupon the relay 8 at the stations which have been locked out will come up and this time release the relay 9 and as soon as relay 8 releases, the relay II will release, causing the relays I1 and 24 in turn to release and thus restore such stations to normal. The release of relays 9 and N at both the calling and called stations will also result in the release of relays I and I2 and consequently the return to normal will be complete at such stations.

The tape transmitter I09, with which the station shown in detail in Fig. 1 is equipped may be such, for instance, as that described in the patent to E. F. Watson, No. 2,055,567, granted September 29, 1936. Any number of the stations of the system may be so equipped but it is not necessary that they be all so equipped. If the line is idle the operation isthe same as that already described, except that the Figures combination for operating contacts I9, the Activate combination for operating contacts 20, the individual call combination for operating contacts 2| or the group call combination for operating contact 22 and the Letters combination for looking out the non-selected stations may be all punched in the tape and transmitted therefrom. The selection is started by the operation of the control switch 6. The operation of the time control switch 6 causes the motors I4 to start on the temporary basis as described above, After four seconds switch 6 will close line I, thereafter the operator or attendant at the calling station will close switch I06 which closes the circuit of the start magnet of the tape transmitter. The tape transmitter will then transmit the signals perforated in the tape. Under these circumstances the first signals perforated in the tape should be a Figures code followed by an activate signal and then the signals representing the stations it is desired to call, followed by the Letters? or "Space signal which will lock out the other stations connected to the system. Thereafter the message will be transmitted from the tape controlled transmitter in accordance with the perforations in the tape.

If it is desired to connect additional stations or a new group of stations this may be accomplished without releasing the connection and starting over manually in the following manner: The Figures combination and the Activate combination are punched in the tape after the conclusion of the message punched in the tape for the previously established connection. These combinations transmitted will operate relay 23 at the stations efiectively on the circuit as before described. A common recall combinationis then punched in the tape which, when transmitted, will resultin the operation of contacts I04. The operation of these contacts at all the stations provided with these contacts including the station where the selecting is taking place places ground through the front contact and right-hand armature of relay 23, contacts I04, winding of relay I02 to battery, resulting in the operation of relay I02. This relay looks through its front contact and inner lower armature to the armature and back contact of relay I03. Relay I03 is now energized in a circuit including the outer lower armature andfront contact of relay I02. Relay 03, however, is slow to operate and will not move its armature for at least four seconds. Therefore, relay I02 is maintained in operation for this period of time. At the end of about four seconds relay I03 operates and releases relay I02 which relay then releases relay I03.

The operation of relay I02 opens the line at theouter upper armature of relay I02 so as to provide the same sort of operation as the operation of the time-controlled switch 6. This foursecond open interval has therefore been sent over the circuit and has resulted in the operation and release of relay 8 which causes the release of relays 9, II, and I! at all the stations not previously selected and also those stations previously selected which are not equipped with tape transmitters and contacts I04. The selecting station and previously selected stations which are equipped with contacts I04 have not been afiected since'the operation of relay I02 has by its innermost upper armature opened the circuit between the armature of relay 8 and the circuit of the counting relays 9 and II. Thus the stations previously selected remain in operative condition.

At. the selecting station relay I02 through its middle upper armature and back contact opens the circuitv to the start magnet I05 of the tape transmitter so as to prevent further transmission from the tape during this four-second period.

Several blank code combinations will be punched in thetape following the first common recall combination. A considerable period of time may elapsefrom the time of the transmission of the first common recall combination punched in the tape until contacts I04 and relay I02 operate to stop the tape transmitter. During this time at least a portion of the following code combination recorded in the tape will be transmitted by the tape, transmitter. Consequently, it is necessary to record certain code combinations in the tape a portion of which may be transmitted during the operation of relay I02 and which will not materially interfere with the operation of the switching equipment at any of the stations. Any suitable spare or unused code combinations may be used for this purpose. In the preferred embodiment of this invention a blank code combination is employed. By a blank code combination is meant a code combination in which all of the impulses are'spacing and represented by no current in the line.

A second common recall combination then punched in the tape will result in a second closure of contacts I04, the operation and release of relays I02 and I03 and the second opening of the line for four seconds resulting in the reoperation of relays 9 and II at stations not previously selected and at stations not having relays I02 and I03, starting of the motors of all of the stations which were not running prior thereto. Since all stations arenow prepared for the reception of the Figures, Activate and the series of selecting combinations, such combinations punched in the tape will result in the selection of wanted stations as hereinbefore described. Thereafter the transmission of Letters or Space signal by the tape transmitter will release the relays 23 and lock out all unwanted stations.

, .Following the second common recall combination several more blank code combinations will be perforated in the tape controlling the trans:

mitter to insure the properoperation oi -the The tape transmitter contacts are illustratedbycontacts Hi9. These contacts transmit signals in accordance with punches in a tape as described in the above-identified patent to Watson. c

Fig. 2 shows another form of the. invention wherein trigger tubes; are usedfor slow-acting means rather than relays adjusted mechanically. In this figure the telegraph line Bl passes through a number of similar stations two of which, are illustrated by stations Gland 5 3 represented by rectangles, and a third by the station shown in full in the diagram comprising the main part of Fig. 2. A line relay 64 is includedin the line as well as a break key 61, aset of keyboard controlled transmitting contacts and a setof tape controlled transmitting contacts I09. The normal condition of the system is closed,with line relay 64 held on its marking contact. In this condition the controlling magnet65 of the teletyp-ewriter is held in a marking condition; At the station fromg which a call is established-a key 66 is momentarily depressed. Thereupon a circuit is established from battery through the resistance 12, winding of relay 14, the contacts of key 66, the back contact and an;upper. armature of relay H to ground. Relay l4 isenergized in this circuit and thereafter pits front contact and inner left-hand armature establishes a holding circuit independent of the key 66. The operation of relay 14 opens i the line at its egouter right-hand armature. By means of, its outer left-hand armature, relay 14 at; the same; time removes a short circuit from about adjustable resistance 15 and fixed resistance 16w r Relay 69 is connected to the spacing contact of line relay 64 and when the line is opened by the right-hand armature of relay 14, the rel y 64 moves to its spacing contact and causes the operation of relay 68. Theyoperation of relay 68 establishes a circuit from battery, through front contact and second outer right-hand armatureof relay 68 through resistances l5, 16, J1 and 18 in series to condenser 19 and thence to ground. c By means of the adjustable resistances l5 and 18this circuit is adjusted so that the condenser 19 will become charged suflicientlyin a period of four seconds to cause the cold cathode tube 80 to flash over. s i.

At all other stations on the circuit, except the calling station where relay Mahas been operated, the relay 68 will establish a circuit from battery, through the front contact and second outer righthand armature of relay 68, the back contact and outer left-hand armature of relay l4 resistances Ti and T8 in series to the condenser 19 and thence to ground. At these stationsand wlth thislower resistance in series with the condenser 19, the condenser will become charged sufiiciently to cause the cold cathode tube 80 to flash over in three seconds, thus reducing the time constant of the circuit by one second. The reason for the two times used is to give agood margin of operation and to be sure that the circuitremains open long enough to operate the tubes at all stations. When the tubes flash over, continuous battery is placed on relay69 in a circuit from battery, through the front contact and second outer righthand armature of relay liflthroughthetube 80 to thewinding of relay-69 and-thence to ground.

This currentwill continueto flow until relay 68 releases. Therefore, relay 69 at all stations except the calling station will operateat the end i of three seconds and thissame relay at the calling station wili operate at the end of four seconds.

The operation of. relay 69 at all the stations places ground throughits upper outer armature and front contact on the winding of relay 1| through the resistance 9| and; causes the operation of relay 1|. This relaylocks in anoperated condition through the front. contact and second upper armature of relay 1|. i v

At the calling station the initial operation of relay 14 has also placed around on the winding of relay 82 through the front contact of the middle left-hand armature of relay (l4. and second upper break contacts of relay "H. w Relay 82 locks through its outer left-hand armature and front contact and second upper operated contacts of relay H after relay 'H has become operated. The operation of relay BZ causes the operation of relay 13 which causes theteletypewriten motor 83 at the calling station to start into operation. The operation of relay 82 also removes a shortcircuit normally placed-about the break key 61, and the transmitting contacts 10 and I09.

The operation of;relay H at the calling station remov es the original holding ground for relay 14 but this relay continues to hold up through the front contact and outer right-handarmature a: relay 82 and the second outer upper operated contacts of relay II. The operationof relay II also places ground on its upper-innermost armature and front contact to cause the operation of busy lamp 84 and at the same time through the front contact and inner upper armature of relay 69 to the pointbetween resistance I2 and the winding of relay ll thereby short-circuiting relay 14 and causing it to release. release of relay. 14

closes the line at its right-hand armature and a back contact and this results in thefmovement of all ofthe line relays 64 to their marking contacts. This in turn releases relay 68 at all stations, with the result that the battery circuit to the r tube 89 is broken, and tube 89 extinguished and relay 69 released. The release of relay 68 com pletes a circuit for the operationof relay 103 from battery through the winding. of relay I93, the right outer break contacts of relay 68 to ground through the uppermost operated contacts of relay "ll. Relay [93 in operating; completes a circuit for maintaining itself operated from battery through its winding and left-hand operatedcontacts to ground through the uppermost operated contacts of relay H. v The operationof relayl03 removes ground from the upper terminal of condenser 88 and permits it to prepare forcharging of the condenser as described hereinafter. c The release of relay 69 at all stations establishes a connection from ground, the upper outer armature and back contact of relay-69 through the frontcontact and lower armature of relay H, the normal contacts of theinner right h'and armature ofrelay 85. to the winding of relay" which operates at all of the stations except the calling station. Relay l3 previouslyoperated at the calling station as described above. The operation of relay l3 atall these other stations now causes the respective motors 83 to start into operation, and all stations are now in condition to respond to signals.

left-hand arrnaturedirectly to ground through the contacts 90. The operation oi relay 92 results in the operation of relay85 whereupon the original energizing circuit for relay I3 is broken and a substitute connection made through the inner right-hand armature of relay 85 and the middle right-hand armature of relay 92 to ground.

At the time that relay 1 l operates, the busy lamp S4 at all stations lights as hereinbefore described, thereby indicating that the circuit is busy. The calling station now transmits the call combination for the stations desired on the circuit. This may takethe form of an individual call which will operate the contacts 93 or a group calling combination which will operate the contacts 94. The oration, however, is the same forthese two conditions. With either contacts 93 or 94 closed monientarily, a connection is established from ground, the front contact and outermost righthand armature of relay 92,1 the contacts 93 or the contacts 94 to the winding of relay 82 so that this relay, which has already been operated at the calling station, will now become operated at the particular stations called. Relay82 at the called stations will lock through the front contact and outer left-hand armature to a ground on the front contact and second upper outer armature of relay H. The operation of" relay 82 also places ground on the Winding of relay 13 to substitute for the connection hereinbefore established. The operation oi relay 82 also removes. the short circuits about the break key fi'l' andkeyboard transmitting contacts ill and tape transmitting contacts of those stations which have been called.

Following this, the sending of the code for- Letters or Space will open the figures contacts' 90, thereby removing the locking ground o r l y 92 a in t eas el x ho ever, will be maintained operated through its left-h nd l t ev and front contac the nner aw r atur and nt. co tac o re ay Ti and the ack onta a d p e te a matu e of relay Q9. The release of relay 9.; at the called stations will have no effect on the teletypewriter motors as these motors are now under the. control of relay 82'.

At the non-called stations, however the re: lease of relay 92 removes ground from the front contact of the middle right-hand armature, thereby releasing the relay l3 and stopping the mos tor 83. The control of the circuit has been re,- moved from these non-called stations by the preceding operations. Since ground is no longer available at these stations through the call key 66 due to the operation of relay 1 I and since relay 'H- will remain operatedthe ensuingperiod; of communication, such non-called stations will be unable to break in on the circuit. At the same time the break key 61 and the transmitting contacts 150 of these non -called stations will remain short-circuited through the right-hand armature and back contact of relay 82. Thus the non-called stations are locked out.

If it is desired to disconnect a station previously called, the "Figures and Actiyate contacts 9i! and 9| are operated through the sending of these codes atthe previously cal'led stations only. This is possible since the motors of the non-called stations have been shut down while the motors of the called stations are still in. operation. The individual disconnect contact 95 is now operated through the sending of: a particular code which is different for each station on the linc. A group of stations may be disconnected by sending a group disconnect signal which will operate a contact similar to contact 95 at'each station of the group. The operation of contact 95extends ground from the front contact and outer right-hand armature of relay 92 through" contact 95 to the lower terminal of the winding of relay 82, thereby caus ing relay 82 to release. The release of this relay breaks the lock through its outer left-hand armature, short-circuits the break key 6"! and transmitting contacts 70 and I09 and removes its control of the motor and control relay 13. When a letters or space signal is now sent, relay 92 releases through the op'ening 'of contacts Si; and removes the ground which during the operation of relay 92 was placed through the inner right-hand armature of relay 85'to cause the release of the motor control relay 13. The motor at the station to be disconnected now stops and the station is in the same condition as anon-called station, described above; a I

To recall or add stations to the system the call and recall key 66 at any of the stations at this time connected to the line is operated. This operates relay 14 from ground through the middle left-hand armature ofr-elay 82 and the contact of key 66 to the winding of relay- M. This opens the line for four seconds at the sending station. as described in making a new call, and line relay 64 at all stations moves to its spacing contact, operating relay 68' as hereinbef'ore described. This starts thetiming circuit of tube as hereinbefore described. In this case again. at the end of three seconds atall the stations except the calling station andat the end of four seconds at the calling stationrelay 69 will operate. Relay ll, however, is locked operated and the opening of the circuit from ground, upper outer armature and back contact of relay 6% removes ground over the circuitlpreviously described to the winding of relay 85, causing the release of relay 85. The release of this relay starts the meters at all of the stations previously cut off the circuit as soon as relay 69 again releases at the end of four seconds as previously described. This is done by placing ground through the upper outer armature and back contact of relay 69.; the front contact and inner lower armature of relay H, the normal con.- tactsof the inner right-hand armature of relay to the winding of relay 13. The circuit is now in the condition it was before the station selcc-- tions were sent when a new call was being placed and the operation to select the added stations is the same as it was for adding new stations.

To return the circuit to normal or disconnect all the stations, the disconnect key 96 is operated at'any of the stations on the circuit at the time. The operation of key 96 places ground used to operate relay 1-3 through thecontacts of key 96 to the winding of relay 9'! which now operates and locks through its inner left-hand armature and front contact. At the station sending the disconnect this also opens the linecircuit at the right-hand armature and back contact of relay 9''! and at the outer lef t-h-andarmaturcand back contact of this relay removes ashort circuit about the resistances Hill and IM. line releases the line relays at all the stations and operates relay 68 thereat. The operation of relay- 68 places battery on the charging circuit of tube 80 and, as previously described, and at the end of three secondsthis tube will flash over, operating relay-69 at all thestations. The op eration of relay- 69- releases relay 85- and places thebattery through the front contact and second outer'right-hand armature of relay 68, the front contact and lower outer armature of relay 69 on The opening of the l3 resistance 98 whereupon current flows through resistances 98 and 99, back contactand outer left-hand armaturerof relay. 91 in shunt with resistors I00 andIDI, front contact and right hand armature of relay I03 to condenser'88 at all the stations except the disconnecting station and through- resistances 98, 99, I00 and IN at the disconnecting station. These resistances are of such a valuemthat when 98 and99 arein the circuit alone, tube 89 will flash over at the end of sixseconds and at the station doing the disconnecting where resistances I00 and IN are also; in the circuit the tube will flash over at the end of leight seconds. I Battery is supplied to the anode of tube 89 through the left-hand armature and front contact ofrelay. 68.9. Atthe stations being disa connected ,at'the end of six seconds when tube 89 flashes over, battery through the left-hand armature of relay 68 and through tube 89 is connected to relay I02.-Relay I02 operates and in turn connects battery to the grounded side of thewinding of relay TI thereby releasingthis relaywhich in turn releases relayl82, and with relays .II, 82 and 85 releasedthe busylamps are extinguished and the motors are stopped at these stations. At the station sending the disconnect, tube 89 flashes over} at the endof eight seconds thereby dropping oii its relays 11,82 and 85, turning off its motor,: its busy lamp and at the same time :removingthe locking ground on relay 91, releasing this I relay and I closing the circuit through the outer right-hand armature and back contact of relay 91. i This last circuit closed operates the line relay 84 at all. stations, causing in turn the release of relay B8 and thereby breaking the battery circuits of tubes .80 and 89, thus returning the circuit to normal condition.

Inorderfito: eliminate the possibility, of relay 08 following the teletypewriter signals which operate the line relay 64, and building up a charge in the, timing circuits of ,tubes, 80 and 89, the back contacts of the middle and inner right-hand armatures of relay 68 place a ground on the battery side .of the charging condensers l9 and 88 each time relay 6B releases thereby discharging j the condensers and only permitting tubes to op,- erate when relay. 68 remains operated for the required periods of 3, 4, 6 or,,8 seconds as hereinbefore described. Where the, operation of this circuit is desired from a punched tape, employing the tape transmitter I09, two additional code combination operated contacts I01 and I08 are provided. After the systemhas been started by gamma.

pressing the call key 06 the transmitter-distributor switch, I06 is operated at the station sending the selection. The selections, including Figures and Activate signals, are then sent over the line from the transmitter-distributor as soon as the relay 14 has released and closed the circuit of the start magnet I05 through the innerrighthand armature and back contactof relay I4 and the inner right-hand armature and backcontact of relay 91. An individual disconnect may be accomplished by including in the tape at the desired point the signals Figures, Activate," Disconnect, for the particular station :to opcrate contacts 95 at the particular station, and Letters. or Space to release relays 92 which prepared for thedisconnect. As in thesystem shown in Fig. 1 blank code combinations are perforated in the tape preceding the switching code combinations as well as following a recall signal to insure the proper operation of the system. To recall any station or stations or disconnectthe system under the control of a punched tapega re- 14 call or disconnect combination is punched in the tape tooperate either contacts I01 or contacts I,08after the contacts 90 and 9| have been operated. Thefloperation of contacts 90 and 9| operates relay 92 as hereinbefore described and places ground from the contact and outer righthand armature. of relay 92 through the left-hand element of the switch I06 to the contacts I01 and I08. When either ofthese contacts then operates, it places ground in the one case over contacts I01 to the winding of relay H for a recall and in the other casethrough contacts I08 to the windingof relay 91 for a disconnect, and the operation of these relays manipulates the, circuit asbefore described. At the same time the circuit of the transmitter-distributor start magnet I05 isopened by the operation of either relay 14, or relay 9'! so as to stop the feedingof further tape untilthe circuit is prepared to receive selecting or disconnecting combinations.

,What isclaimed is:

,L'In ,1 communication system, a communication channel including a plurality of stations each provided with teletypewriter receiving mechanism and each provided with a plurality of contact sets selectively operated by said mechanism, transmitting mechanism at said stations, tape transmitters ,at' a minimum of one or said stations, slow-acting means at each of said stations for sending a prolonged calling-in, signal over said channel, and means including one of said contact sets at a transmitting station provided with one ofsaid tape transmitters responsive to the transmission of a. code for operating said slow-acting means andhior correspondingly delaying .the. operation of said tape transmitter.

'2;In1acommunication system, a communica-. tion channel interconnecting a plurality of stations=each provided with teletypewriter receiving mechanism, code transmitting mechanism at said stationsforjtransmitting code signals over said channel including storage type code transmitting mechanisms atmore than one of said stations, means controllable by said storage type code transmitting mechanism for transmitting noncode signals, and means selectively operable at each of saidstations in response to signals includingnon-code signals the transmission of which is controllable by any of said storage type transmitting mechanisms for qualifying one or more of theteletypewriter receiving mechanisms selectively to record] message material subsequently transmitted by said storage type transmitter. h l 3. In a communication system, a communication channel interconnecting a plurality of stations each provided with teletypewriter receiving mechanism normally disqualified against message recording, transmitting mechanism at each of said' stations for transmitting over said channel including signal storage record controlled transmitting mechanism at more than one of said stationspmeans selectively operable at each of said stations in response to signals the transmission of which is controllable by any of said record controlled transmitting mechanisms for qualifying one or more of the teletypewriter receiving mechanism selectively to record message material subsequently transmitted by said storage record controlled transmitting mechanism, and means at each station responsiveto a common signal transmitted under control of said record controlled transmitting mechanism for renderingpunqualified stations unresponsive to subsequent message-signals;

4. In a communication system, a plurality of telegraph stations, a channel of communication interconnecting all of said stations, a plurality of telegraph receiving recording mechanisms at a plurality of said stations, control apparatus at said plurality of stations for selectively conditioning the receiving recording mechanism for recording received signals, signaling apparatus at a plurality of stations for transmitting signals over said channel for actuating said control apparatus to selectively condition any of said receiving mechanisms, and storage type signaling apparatus at one of said stations for controlling the transmission of signals over said channel for actuating said control apparatus to selectively condition any of said receiving mechanisms.

5. In a communication system, a communication channel interconnecting a plurality of stations each provided with teletypewriter receiving mechanism normally disqualified against message recording, transmitting mechanism at said stations for transmitting over said channel including signal storage record controlled transmitting mechanism, means at each station for qualifying the teletypewriter receiving mechanism thereat to record message material, manually operable means at each station for actuating the qualifying means thereat, means selectively operable at each of said stations in response to signals the transmission of which is controllable by any of said record controlled transmitting mechanisms for actuating said qualifying means, and means at each station responsive to a common signal the transmission of which is controllable by any of said record controlled transmitting mechanisms for rendering unoperated ones of said qualifying means unresponsive to their qualifying signals.

6. In a communication system; a communication channel interconnecting a plurality of stations each provided with a. teletypewriter receiving mechanism normally disqualified against message recording, manually operable signal transmitting means .at more than one of said stations, storage record controlled signal transmitting means at more than one of those stations having manually operable signal transmitting means, means selectively operable at each of said stations in response to signals the transmission of which is controllable by any of said manually operable or any of said storage record controlled signal transmitting means for qualifying one or more of said teletypewriter receiving mechanisms to record message material subsequently transmitted from any of said transmitting means, and means responsive to a common signal the transmission of which is controllable by any of said transmitting means for renderin unqualified ones of said stations unresponsive to subsequent message or selecting signals and, for disabling the transmitting means at said unqualifled stations.

7. In a communication system, a communication'channel interconnecting a plurality of stations each provided with teletypewriter receiving mechanism normally disqualified against message reception, manually controlled slow-acting means at each of said stations for transmitting over said channel a prolonged calling-in signal for qualifying said stations on a provisional basis, tape transmitters at a plurality of stations, means at each station selectively responsive upon provisional qualification of the station to signals transmitted under the control of any of said tape transmitters for qualifying said station on a per- 16 manent basis, means responsive to a common signal transmitted under the control of said tape transmitter for disqualifying on a locked-out basis those stations not permanently qualified, other slow-acting means at those stations having tape transmitters and selectively responsive to signals'transmitted under the control of any of said tape transmitters for requalifying said locked-out stations on a provisional basis, and means controlled by the second-mentioned slowacting means for correspondingly delaying operation of the tape transmitter transmitting said signals. 7

8. In a communication system, a communication channel interconnecting a plurality of stations each provided with teletypewriter receiving mechanism normally disqualified against message reception, manually controlled means at each of said stations for initiating a prolonged callingin signal, slow-acting means at each of said stations responsive to said calling-in signal for qualifying said station on a provisional basis, said slow-acting means at the station initiating said calling-in signal also operating to terminate said signal, tape transmitters at a plurality of said stations, means at each station selectively responsive to signals transmitted under the control of any of said tape transmitters for qualifying said station on a permanent basis, means responsive to the common signal transmitted under the control of said tape transmitter for disqualifying on a locked-out basis those stations not permanently qualified, means selectively responsive at permanently qualified ones of said stations to signals transmitted under the control of said tape transmitter for disqualifying said stations on a locked-out basis, means selectively responsive to signals transmitted under the control of any of said tape transmitters for initiating a prolonged calling-in signal for requalifying said locked-out stations on a provisional basis, and means selectively effective at each permanently qualified station having a tape transmitter, in response to signals transmitted under the control of any of said tape transmitters, for initiating a prolonged disconnect signal to restore said permanently qualified stations and said locked-out stations to the normal condition or disqualification.

9. In a communication system having a communication channel interconnecting a plurality of stations provided with teletypewriter receiving mechanism normally disqualified against message recording, the method of selectively qualifying and requalifying stations to record message material which comprises the following steps: (1) qualifying all stations on a provisional basis to respond in normal manner to signals transmitted over said channel, (2) selectively qualifying any desired ones of said stations on a permanent basis to respond in normal manner to signals transmitted over said channel, (3) disqualifying all others of said stations on a locked-out basis against any signal responsive operation except restoration to the condition of normal disqualification, (4) transmitting message material for recording by said permanently qualified stations, (5) restoring said locked-out stations to condition of normal disqualification while holding all others of said stations permanently qualified, (6) requalifying all of said restored stations on a provisional basis, ('7) qualifying one or more of said provisionally requalified stations on a permanent basis, (8) disqualifying all others of said provisionally requalified stations on a lockeda en -724 fying all stations on a provisional basis to respond in normal manner to signals transmitted over said channel, (2) selectively qualifying any desired ones of said stations on a permanent basis to respond in normal manner to signals transmitted over said channel, (3) disqualifying all others of said stations on a locked-out basis, (4) transmitting message material for recording by said permanently qualified stations, (5) selectively converting any of said permanently qualified stations from the condition or permanent qualification to locked-out condition, (6) requalifying all of said locked-out stations on a provisional basis, (7) qualifying one or more of said provisionally requalified stations on a permanent basis, (8) disqualifying all others of said provisionally requalifid stations on a locked-out basis, (9) transmitting message material to be recorded by the now permanently qualified stations, (10) and restoring all stations to the condition of normal disqualification.

11. In a communication system, a communication channel interconnecting a plurality of stations each provided with teletypewriter receiving mechanism, transmitting mechanism at said stations for transmitting over said channel including storage type transmitting mechanism at more than one of said stations, and means selectively operable at each of said stations in response to signals the transmission of which is controllable by any of said storage type transmitting mechanisms for qualifying, disqualifying and requalifying one or more of the teletypewriter receiving mechanisms selectively to record message material subsequently transmitted by said storage type transmitter.

12. In a communication system, a communication channel interconnecting a plurality of stations each provided with teletypewriter receiving mechanism, code transmitting mechanism at said stations for transmitting code signals over said channel including storage type code signal transmitting mechanisms at more than one of said stations, means controllable by said storage type transmitting mechanisms for transmitting noncode signals, and means selectively operable at each of said stations in response to signals including non-code signals the transmission of which is completely controllable by any of said storage type transmitting mechanisms for qualitying one or more of the teletypewriter receiving mechanisms selectively to record message material subsequently transmitted by said storage type transmitter.

13. In a communication system, a communication channel interconnecting a plurality oistations each provided with teletypewriter receiving mechanism normally disqualified against message recording, transmitting mechanism at each of said stations for transmitting over said channel including signal storage record controlled transmitting mechanism at more than one of said stations, means selectively operable at each of. said-'11 stations iiri: response to 1 signals 1' the transmission" f? which is awholly' icontrollable byany of"; isaid i recordiicontko1led1 stransmitting mechanisms" forl qualifiying i one I on more of the teletypewriter 1 receiving "mechanisms selectively to record message-material subsequently transmitted by usaidu storageilrecord? controlled ltransmitting mechanism, and riieans 'at each station responsive to ai ;common signalmtransmitted under control of said record 0 lled transmittingimechanism roatrieadsnag canned stations unresponsive to subsequent message signals.

14. In a communication system, a communication channel interconnecting a, plurality of stations each provided with a teletypewriter receiving mechanism normally disqualified against message recording, manually operable signal transmitting means at more than one of said stations, a storage record controlled signal transmitting means at more than one of those stations having manually operable signal transmitting means, means selectively operable at each of said stations in response to signals the transmission of which is wholly controllable by any of said manually operable or any of said storage record controlled signal transmitting means for qualifying one or more of said teletypewriter receiving mechanisms to record message material subsequently submitted from any of said transmitting means, and means responsive to a common signal the transmission of which is controllable by any of said transmitting means for rendering unqualified ones of said stations unresponsive to subsequent message or selecting signals and for disabling the transmitting means at said unqualified stations. 15. In a telegraph system, a communication channel, :a storage type permutation code signal transmitter associated with said channel, means responsive to a permutation code signal transmitted by said transmitter for transmitting a prolonged non-code signal, and means controlled by said prolonged signal transmitting means for suppressing operation of said storage type transmitter during transmission of said prolonged signal.

16. In a telegraph system, a communication channel, a signal transmitting distributor associated with said channel, a signal record sensing mechanism adapted to supply signals for transmission by said distributor, means responsive to a permutation code signal transmitted by said distributor under the control of said sensing mechanism for transmitting a prolonged noncode signal, and means controlled by said prolonged signal transmitting means for suppressing operation of said distributor and sensing mechanism during transmission of said prolonged signal. 7

17. In a telegraph system, a communication channel, a plurality of stations associated with said channel, means at each station responsive to a prolonged signal for conditioning said stations in a predetermined manner, a storage type permutation code signal transmitter associated with said channel, means responsive to a permutation code signal transmitted by said transmitter for transmitting said prolonged signal, and means controlled by said prolonged signal transmitting means for suppressing operation of said storage type transmitter during transmission of said prolonged signal.

18. In a communication system, a communication channel interconnecting a plurality of stations having alternative conditions of selection and exclusion relative to message transmission

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