US2205406A - Multichannel telegraph system - Google Patents

Description

June 25, 1940. P. HOLCOMB, JR 2,205,405

- I MULTICHANNEL TELEGRAPH-SYSTEM Filed July 15, 1937- .4 Sheets-Sheet 1 SWO STATION A REC.'

' A0 EY June 25, 1940. P. HOLCOMB, JR

MULTICHANNEL TELEGRAPH SYSTEM Filed July 15, 1957 4 Sheets-Sheet 2 INVENTOR P HOLCOMB JR wgfi zuad ATTQR EY STATION B J1me ?5, 1940. HQLCQMB. JR 7 2,205,406

uumzcwmm. TELEGRAPH SYSTEM Filed July 15, 19:57 4 sheets-sheets I95 STATION C r FIG.3

INVENTOR P. HOLCOM B JR.

TO NEY June 25, 1940.

P. HOLCOMB, JR

MULTICHANNEL TELEGRAPH SYSTEM Filed July 15, 1937 4 Sheets-Sheet 4 .F'IGQ4.

STATIOND TO TRANS.

INVENTOR P. HoLcdMB JR. W/WQ A OR EY Patented June 25, 1940 UNITED STATES MULTICHANNEL TELEGRAPH SYSTEM Philo Holcomb, Jr., Malba, N. Y., assignor to The Western Union Telegraph Company, New York, N. Y., a corporation of New York Application July 15, 1937, Serial No. 153,748

30 Claims.

This invention relates to a signalling system and more particularly to a system involving the transmission of signals from a variable number of sources simultaneously over a lane of trafiic,

such as a multiplex channel, to separate receiving devices or recorders. A system of this character is commonly termed a varioplex or expanding channel? system.

A lane of trafiic as used in the following 'description and referred to in the claims is the route or medium over which signalling is accomplished normally. Among other things a lane of trafllc may be comprised of any of the following elements: a wireor a cable strand or conductor, a multiplex distributor channel, a side of a duplex or quadruplex, a carrier current channel, a superimposed circuit, or a radio band channel or circuit. It may also be comprised of any combination of two or more of the aforementioned elements such as a wire and a multiplex distributor channel, a cable conductor, a side of a duplex and a superimposed circuit, etc.

A preferred embodiment of the invention comprises a multiplex telegraph channel or its equivalent and means for connecting. to said channel a number of transmitters 'and their corresponding receiving instruments, either in groups according to any of the possible combinations or singly, each transmitter having characters or signals to transmit, at all times sharing the channel timewith the other busy transmitters in the group, or occupying substantially the 'full channel time when it is the only one busy.

For example: ten transmitters, each controlled by one of ten operators, all of whom may be located in the same ccnt'ral ofiice or in remote branch offices, and none of whose business is sufiicient to occupy the full time of the lane of traffic (such as a multiplex channel) but whose aggregate business will keep such a channel busy, are associated with a single multiplex channel in accordance with one embodiment of this invention. If it be assumed that the capacity of the channel is sixty words per minute, when only one operator is transmitting he will have complete possession of the channel and his transmission will be at the rate of sixty words per minute. With two operators connected to the multiplex channel, each will transmit at the rate of thirty Words per minute and likewise with three operators connected, the transmission rate for each will be twenty words per minute and so on up to the limit of operators assigned to this particular channel. It will be apparent that the capacity of the lane of traffic may be divided unequally between the transmitters or sub-channels, if desired.

When there are a number'of transmitters operating, it may happen at some particular time 5 that one or more of them will have an abnormally large amount of messages or stored trafiic to be transmitted while the rest have relatively little. In order to more nearly equal-' ize the amount of un-transmitted material among the transmitters, it is sometimes advantageous to be able to re-allocate the lane time so that the over-loaded transmitters will operate at a faster rate until their congestion has been relieved. j

One'object of the invention is to providean improved signalling system of this character in which the transmitting capacity of the lane may be allocated in accordance with traflic fluctuations.

Another object of the invention is to provide an improved telegraph system comprising a lane of traffic and means of varyingthe number of signalling channels operating over said lane arranged to utilize a predetermined part of the full lane time as long as any of the channels are operating.

Another object of the invention is to provide a telegraph system of the character described comprising a variable number of transmitters operable in a prearranged order over a lane of trafiic and substantially occupying the full lane time, with manual'means for stopping and starting the operation of both the sending and receiving apparatus at a predetermined point to effect a re-allocation of lane time.

A further object of the invention'is to provide such a telegraph system in which are incorporated automatic means for re-allocating the lane time without the necessity of interrupting the operation of the system.

Further objects of the invention are to provide, in a varioplex system, a simplified switching arrangement for controlling the connection of the operative sending and receiving devices to the lane of trafilc and for indicating and eiTecting re-allocation of channels when desired; to reduce the complexity of the apparatus required; and to provide a system in which the possibility of faulty operation is guarded against or minimized by checking or indicating the channel pattern continuously or at frequent intervals.

In order that a better understanding may be obtained and a ready application made of this invention, a detailed description of it will now be made having reference to the accompanying drawings which illustrate two embodiments of the invention.

In the drawings,

Fig. 1 is a circuit diagram showing the transmitting equipment of a manually controlled system operating over a single synchronous multiplex channel;

Fig. 2 is a similar view of the receiving equipment in the station at the other end of the multiplex channel; and

Figs. 3 and 4 are similar views of a modified system in which the re-allocation of channels is effected automatically.

It is to be understood that transmitting and receiving apparatus may be provided at each station so that simultaneous two-way communication will be afforded. It will be evident to one skilled in the art that separate channels may be used for the incoming and outgoing signals. and also that communication facilities may be duplexed to accomplish two-way operation of the telegraph system provided by this invention. Inasmuch as any transmission medium may constitute the lane of traffic as defined hereinbefore, and as this transmission medium forms no part of this invention, it is desired that it be understood that the particular lane of traflic shown shall constitute no limitation in the application of the Invention.

Reference will be had first to Fig. lwhich shows at station A the transmitting equipment which comprises a number of code telegraph transmitters TI, T2, and T3 (three such are shown although the number is unlimited). The transmitters are illustrated as tape transmitters of the type shown in the patent to Benjamin #1,298,440 granted March 25, 1919, but may be storage transmitters of any other suitable type. As determined by the perforations in the tape the tongues of each transmitter may be set against either the marking or spacing bus bars; and in this description negative potential will be used for marking and positive potential for spacing, although these polarities may be reversed if desired. One terminal of each stepping magnet SMI, SM2 and SM3 is connected to ground. The other terminals of the magnets and the tongues of each transmitter are connected to stationary contacts of the transmitting grouping switch GSa. The arms or movable contacts 40 to 43, 44 to 41, etc., and I03, I04 and I05 of the transmitting grouping switch GSa are arranged so that they all may be moved simultaneously by some means such as a common shaft to which they are secured mechanically (but not electrically). Of the six sections of the grouping switch GSa, interposed between the transmitters TI, T2 and T3 and the selector Sa, the complete internal connections of only those indicated by U and Z are shown. However, it should be understood that sections V, W, X and Y are similar to and connected the same as sections U and Z. The selector switch Sa, which is illustrated as a step-by-step switch having six contact arms or wipers 90, 9|, 92, 93, 94 and 95, is arranged to connect the busy transmitters in predetermined order, in accordance with the setting of the grouping switch GSa, to the transmission circuit or lane of traflic. Thus the grouping switch GSa preselects the transmitters to determine the channel pattern, i. e., whether one, two or all three channels are operative to transmit, and the switch Sa controls the operative transmitters so that the lane time is divided between them. If receiving apparatus is also to be located at station A for duplex operation of the system, the movable arms of the receiving grouping switch are preferably arranged so that they also may be moved simultaneously with those of the transmitting grouping switch GSa in order that the operative channels in both directions may correspond at all times.

The arms of the transmitting grouping switch GSa are connected to stationary bank contacts 48 to 53, 55 to 60, etc., engaged by the wipers -95 inclusive of the transmitting selector Sa. The six rotatable arms 9095 are advanced simultaneously one stud at a time by the stepping magnet 96. Five of the rotatable arms of the transmitting selector Sa connect with segments 1 to 5 of ring 91 of the transmitting multiplex distributor TD, the solid ring 98 of which is connected to the apex of the duplex line L. The transmitting distributor TD is also provided with a pair of local rings 99 and I00, the latter being connected to a source of potential. Segment 6 of ring 99 is connected to the sixth rotatable arm of the transmitting selector Sa. Segment 7 of ring 99 is connected to one side of the selector magnet 90, the other terminal of which is con nected to ground through contaoii-IOI.and tongue I02 of the control relay CRa. Contacts GI, 68 and 15 of the transmitting selector Sa connect respectively through movable arms I03, I04 and I05 of the transmitting grouping switch GSa to positive or negative potential depending upon the position of the grouping switch. Contact 54 of the selector So is connected to the arm I06 of the signal switch SWa, the contacts I01 and I08 of which are connected to the arms I09 and H0 of the control switch CSa which, in turn, connect respectively to positive and negative potential, either directly at contacts III and H2 or through the windings H3 and H4 of the control relay CRa depending on whether the control switch CSa is to the left or to the right. Contact 82 of the selector So is supplied with either positive or negative potential by tongue II5 of the control relay CRa which is pivoted between contacts H6 and Ill. Also segment 8 of ring 99 is connected through conductor II8 to one side of the winding II9 of the control relay CRa.

The operation of the transmitting apparatus is as follows: Assume that the transmitting grouping switch GSa is set to position 123, as shown on the dial Do in the drawings, that the pivoted arms 90 to 95 inclusive of the transmitting selector Sa are on contacts 48, 55, 62, 69, I8 and 83, respectively, that the control switch CSa is to the left, that the control relay CRa is unoperated, with tongues I02 and H5 on their left contacts IOI and I I6, that all transmitters TI, T2 and T3 have ample supplies of tape and that the brush arm BI of the transmitting distributor TD is passing onto segment 1 of ring 91. When this occurs an impulse is sent from contact I20 of transmitter TI over conductor II to several of the stationary contacts of section U of the transmitting grouping switch GSa, arm 40 of which provides the only connection beyond the grouping switch and that to contact 48 of the transmitting selector Sa, whence the impulse is carried through rotatable arm 90 and conductor I2I to segment 1 of the ring 91 of the transmitting distributor TD, through brush BI to solid ring 98 and thence over conductor I22 to the line L. The other contacts of transmitter TI are connected respectively to segments 2, 3, 4 and 5 of ring 91 of the distributor in a manner similar to that just described for contact I20, so that as brush BI crosses these segments, marking or spacing impulses from the contacts of transmitter TI are sent to the line L corresponding to the code combination perforated in the tape in said transmitter. Following this sequence of events brush B2 crosses segment 6 of ring 99 sending an impulse from a source of potential, connected to ring I 08, through brush B2, segment 6 and conductor I23 to the rotatable arm 95 of the transmitting selector Sa from which it is transferred to contact 83 of the selector and thence carried through arm 44 of section Z of the grouping switch GSa, over conductor I6 to one terminal of the stepping magnet SMI of transmitter TI, the other terminal of which magnet is connected to ground; Thus the steppingl magnet SMI is energized momentarily which causes the tape to besteppcd forward one character and leaves-the transmitter TI ready to send anew code combi-' nation. As-brush B2 advances, it "crosses segment 7 of ring 99 and animpulse is sent over conductor I24 through the winding of the stepping magnet 96 and to ground through the left contact Hit-and tongue III2 of the control relay .CRa.- .Thus the stepping magnet 95 is energized which causes the six rotatable arms 90 to .95 inclusive g to advance to.contacts.69,56,, 83, Ill, I1 and 84.

Iii)

Passage of the brush B2 over segment 8 of ring 1 99 sends an impulse overconductor-i'lll to windings' H9 and I25 of the polar-control relay Ci't'a; through winding H9 in a spacing direction and through winding I25 in a marking direction, thus having .no efiect on this relay, its tongues I 02 and H remaining on their left hand contacts IOI and H6 respectively. I

As the brush BI passes over the segments 1 to 5 of ring 91 on the succeeding revolutiona character from transmitter T2 is sent to the line L since arm M of the grouping switch GSa, contact 49 and arm 90 of the selector Sa connect contact I26 of transmitter T2 with segment 1 of ring 91,

present setting of the grouping switch GSa, the

latter contacts are instrumental in selecting a character from transmitter TI. Hence, on the third revolution of the brushes BI and B2, a character will again be sent from transmitter TI. In a like manner a character from transmitter T2 will be sent on the fourth revolution of the brushes BI and B2. However, on the fifth and sixth revolutions of the brushes BI and B2, when the rotatable arms 90 to95 inclusive of the switch Sa are on contacts. 52, 59, 66, I3, 80 and 8'! and 53, 60, 61, I4, 8| and 83 of. the selector Sa, characters are sent from transmitter T3. six revolutions of the brushes BI and B2 of the transmitting distributor TD, two characters have been sent from each of the three transmitters TI, T2 and T3, although not in that order.- The seventh revolution of the brushes BI and B2 finds the selector arms 90 to 95 inclusive on contacts 54, GI, 68, I5, 82 and 89, at which time there is no transmission from any of the transmitters TI, T2 or T3, but instead a combination of sig- -Thus, in

nals, which in this instance areall marking, or negative impulses. is sent. At the receiving station B this signal combination is used to operate a signal, to give an indication of the particular contacts.

Referring now to Fig. 2, the receiving apparatus at station B comprises threeprinters PI, P2 and P3, the receiving grouping switch GSb, the receiving selector Sb, the receiving control relay switch, selector and distributor are precisely similar to thoseof the corresponding apparatus at station A previously described in detail, except for contacts I33, I30, I i'I', I54, IGI and I68 of the selector Sb associated .with auxiliary devices which will be considered hereinafter.

'Assurne that the groupingv switch GSb is in position 1--23 as shown on the'dial Db (all three channels operative), that the rotatable arms I69 to I'M inclusive of selector Sb are on contacts I21, I33, MI, I48, I55 and I62 respectively, that the tongue I15 of control relay CRb is on its marking or right hand contact I16 and CRb and the multiplex receiving distributor RD. .The interconnections of the printers, grouping that the receiving distributor brush B3 is just passing onto segment 1 'of receiving ring III of the distributor RD, The multiplex distributor RD is maintained in synchronism with the one at the-sending station A in accordance with the usual multiplex practice, so it can be assumed that the sending brush also is just passing onto the corresponding segment of the transmitting distributor. Since circuits have been prepared between receiving distributor segments 1 to 6 and magnets 1 to 6 of printer PI similar to those described for the transmitting distributor and transmitter TI, the signal-combination. setup on the latter will be received fromthe line L on ring "8 and transferred to printer PI. With each passage of the brush B4 over local segment I of ring I19 the rotatable arms I69 to I14 inclusive of selector Sb are advanced one contact by energization of the stepping magnet I9I throughthe local circuit. Hence the signal combinations from transmittcrsTI, T2 and T3 are received on printers PI, P2 and P3, respectively.

Operation continues in this'manner as long as all transmitters TI, T2 and T3 are supplied with perforated tape, one character being sent over the line L on every revolution of the distributor brushes, except for the one revolution when the giving the attendant an indication that transmitters TI, T2 and T3 are connected at station A. The marking signal received on segment 5 of ring I11 of the receiving distributor sends a marking impulse to control relay CRb which keeps its tongue I15 on the right hand contact I18.

- when a marking impulse is received on segment 1 of ring I11, it operates a signal I83. The sig nals or indicators I80'I83, inclusive, may be neon lamps or other signalling devices.

When it becomes desirable to re-allocate the lane time between the transmitters for any reason such as the supply of tape for one or more transmitters, for instance the transmitter T8, becoming exhausted, the attendant at the sending end (Fig. 1) throws the control switch CSa to the right. When next the rotatable arms 90 to 95 inclusive of the selector Sa rest on contacts 54, 8|, 88, 15, 82 and 89 and the brush BI crosses segment 1 of ring 91, the marking (negative) signal that issent to line L originates, as before,

at the battery connected to contact II2 of the control switch CSa but now passes through winding II4 of the control relay CRa in a marking direction, thus moving'the tongues I02 and H to their right or marking contactsv I84 and H1.

If the signal switch SWais set on its right contact I01- to send a spacing signal to line from segment 1 of ring 91, this signal originates at contact III of the control switchCSa and passes through winding II3 of the control relay CRa in a marking direction, the effect on this relay being the same as in the preceding instance. Thus switch SWa controls a signal at the receiving station without affecting the apparatus at the sending station, thereby providing a control or signalling channel that may be used for any desired purpose. As soon as the tongue I02 reaches contact I84, the relay CM is looked through its winding I25, marking potential beingapplied from contact I I2 of the control switch CSa and ground from the tongue I02. As the brush BI passes over segments .2, 3 and 4 of ring 91 marking signals are transmitted as before. 0n crossing segment 5, however, a spacing signal is sent to line L sincetongue II5 of the control relay CRa is now on its right contact H1. The passage of brush B2 over segment 6 of ring v99 produces no result, the circuit being incomplete beyond the arm 95 of selector Sa. Also the contact of brush B2 with segment 7 of ring 99 does not result in a stepping of the selector So since the ground for the stepping. magnet 98 has been are theirnormal operating positions.

Thissequence of events is repeated on each revolution of the distributor as long as the control switch 05a is maintained in its right hand position, the selector switch so stopping its normal rotation during this period. The attendant then turns the transmitting grouping switch GSa to the new setting, shown on the dial Da.as'.12 I

in this case if transmitter T3 is to be eliminated. An inspection of the grouping' switch will now show that there are no complete circuits between the contacts of transmitter T3 and the selector So. -It will also be seen that when the selector arms are advanced, signals will be transmitted alternately from transmitters TI and T2. In

addition, with the selector- Sa still being held in the position in which it was stopped, marking f potential is applied to segments 2 and 3 and spacing potential to segment 4 of ring 97 by the grouping s switch arms I08, I04 and I05, respectively. Thus an indication is sent to the receiving station of the desired re-allocation of the channels.

After allowing a prearranged length of time to elapse or after receiving some signal from the attendant at'the receiving station B indicating that he has set his receiving grouping switch in position 1-2, the attendant at the transmitting station A throws his control switch CS1: to the left. 1 of ring 91 by the brush BI the control relay cm: is unaffected: since its operating windings H3 and H4 are shunted by arms I09 and H0 of the control switch CSa. Hence a marking signal is sent to line L when brush BI reaches segment 5v of ring 91, and the stepping magnet 98 is energized when brush B2 reaches segment 7 of ring 99 thus rotating the arms 90 to 95 inclusive to such a position that a character will be transmitted from transmitter TI on the following revolution of .the distributor as described above. Operation will then go on as before except that characters will be sent alternately from transmitters TI and T2, the transmitting time previously utilizedby transmitter T3 being divided between the other transmitters.

Referring to Fig. 2, the results produced by the manipulations of the transmitting control switch and grouping switch on the receiving apparatus will be described. .Assume that the control switch CSa at the transmitting stationA hasbeen thrown to the right. When next the rotatable arms I69 to I14 inclusive of selector Sb are in contact with studs I33, I40, I41, I54, I 8| and IE8 and the brush B3 passes over segments 1 to 4 of ring I11 of the receiving distributor RD, marking impulses are sent to indicators I80, I8I and I82, and signal I83 as before.

B3 a spacing signal is sent through the winding I85 of the control relay CRb moving the tongue I to its left hand contact- I88. As brush B4 crosses local segment 6 of ring I19 an impulse is sent through contact arm I14 and contact I68 of the switch Sb, the arm I81 and right hand contact I88 of the cut-off switch I89, the bell I90, contact I88 and tongue I15 of the control relay OR!) to ground, thus operating the bell I90. As segment. '7 of ring I19 is crossed by brush B4, the selector steppingmagnet I9| is not ener-' gizedsince its ground has been removed from contact I16 of the control relay CRb. Hence the receiving selector Sb has been stopped in the position corresponding to that in which the transmitting selector Sa wasstopped. The bell I90 is v operated on each revolution ofthe distributor and attracts the attention of the attendant who may silence it if hedesires by the cut-off switch As soon as the transmitting grouping switch has been setto its new position 1-2 the attend.- ant at the receiving station B refers to the indicators I80, I8I and I82, the latter now rendered inoperative because of the reception of a spacing signal on segment 4 of ring "I11, andsets' his receiving groupingswitch CSb accordingly to posi- -tion l 2'. This cuts off printerPi from the selector "Sb and provides for the reception of char- "acters alternately on printers PI and P2. He then notifies the attendant at the gtransmitting station Athat the receiving apparatus is r'eady to proceed onthe new schedule. He may do this by As segment 5 of ring 177 is reached by the brush- On the following engagement of segment it) to the new position 1.-2, the change will be indicated at station A in the same manner as the change at station Awas indicated at station B. The attendants at stations A and B then throw the control switches CS0. and 08b to the left. The next revolution of the distributor finds a marking signal being received on segment 5 of ring I" which is transferred to the winding I85 of the control relay CRb and causes the tongue I15 to be moved to its right hand contact I16, thus restoring the ground to the selector stepping magnet I9I. When brush B4 then crosses segment 7 of ring I19 the selector arms are advanced to positions such that, on the following revolution of the distributor,. the character received from transmitter TI is registered on printer PI. Operation then continues as before with characters being received'alternately on printers PI and P2.

The operation of the signal lamps I80, I8I and I82 may be utilized to designate the channel pattern" by employing arbitrary code signals to indicate changes from an existing pattern. For example, each of the eight possible code combinations may refer to one of eight channels, in

the status of which a changeis desired; that is, if operative the channel is to be switched out and if inoperative, the channel is to be entered onto the system. Thus, the re-allocation signaling may be accomplished by a code signal rather than by the use of lamps or other indicating devices which are individual to each channel and which require individual operating pulses.

The transmitting control switch CS is used also for synchronizing the transmitting and receiving selectors Sc and Sb when the system is being put into operation. When the transmitting and receiving distributors TD and RD have been synchronized in accordance with the usual multiplex practice, the selectors will not necessarily be in step with one another. The trans mitting control switch is thrown to the right and when next the transmitting selector arms 30 to 35 inclusive are on contacts 54, 6|, 88, I5, 82 and 80, further stepping of the selector is prevented as described -above. Subsequently, when the arms I69 to I14 inclusive of the receiving selector reach contacts I33, I40, I41, I54, IBI and I68, further stepping of this selector also is prevented until such time as the transmitting control switch is thrown to the left when both selectors are stepped along in synchronism.

Each arm of the transmitting selector Sa is shown (Fig. 1) associated with a bank of seven contacts, six of which are instrumental in selecting an element of the various transmitters .TI, T2 and T3 in cooperation with the grouping switch GSa. The seventh contact is used for reallocating the lane time and for synchronizing the transmitting and receiving selectors so and Sb in the manner described above. On reducing this invention to practice, in order that such a system be not unduly wasteful of lane time, it will be advantageous to use a larger number of-contacts in each bank of the selector So, for example twenty-five. In a system having three channels or transmitters, they can be divided into .four groups of six contacts for transmitter selection purposes. In thiscase the contacts of one group may be distributed as indicated and multipled' to corresponding contacts of the other groups of ,the selector switch bank. The twenty-fifth contact will be available for reallocating and synchronizing purposes. Where more than three transmitters are used in this system, the transmitting selector Sa must be provided with more than seven contacts in each bank to accommodate the extra transmitters if equal division of the transmitting time between operative or busy channels is desired. In any event the receiving selector Sb will of necessity be arranged substantially similar to the transmitting selector Sa. Obvi ously when the number of channels exceeds four or five, code signals may be sent for reallocating purposes.

The devices for controlling the selectorsSa and Sb for re-allocating and synchronizing purposes are not absolutely essential for the successful operation of this improved telegraph system and may be omitted in the interest of economy without impairing the system in any way other than retarding the reallocating and-synchronizing operations. The omission of this control feature will allow the elimination of the following apparatus: from Fig. l, the signal switch SWa, arms I03, I04 and I05 of the grouping switch GSa and their associated contacts, the control relay CRO.

control switch 'CSa and segment 8 of local ring -neis operating-over the lane or on some other convenient lane of traffic, or by making the changes in accordance with a pre-arranged schedule. receiving selectors So and Sb, the grouping switches GSa and GSb are set to position I2--3 and transmitter T3 is rendered operative. Sig- To synchronize the transmitting and nals are sent from this transmitter and the re-@ ceiving selector Sb is manually, as well asautomatically, operated until these signals are always received on printer P3 as explained below.

If the selectors So and Sb are equipped with banks of 25 contacts each, connected as indicated above, the contacts corresponding to 52, 53 and 54; 59, 60 and 6|, etc. (Fig. 1); and I3I, I32 and I33; I38, I39 and I40, etc. (Fig. 2), are employed in transmitting character signals from transmitter T3 and receiving them on printer P3. Inasmuch as this is the only time in the entire cycle of operation of the selector So that three successive characters are sent from the same transmitter, it is apparent that there is only one time when these characters will be received on a corresponding printer. This will occur when the receivingselector Sb-is in synchronism with the transmitting selector Sa.

While the foregoing description has been devoted to but two .possible combinations of the Sa and Sb as shown in Figs. 1 and 2 are arranged so that anydesired combination of one or more channels may be connected to a lane of traffic for operation in a manner similar to that described above. The seven possible combinations are indicated on the dials Da and Db. By assuming the grouping switches GSa and G817 set in the various positions corresponding to those on the dials Da and Db, and by inspecting the vvarious circuits between the transmitters and printers and their respective distributors TD and RD it will be apparent that provisions are made for all possible combinations with equal division of the transmitting time. At any time, when the selectors Sa and Sb have been stopped for reallocation of lane time or for any 0 Ler reason, one or more transmitters and printers may be enteredonto or closed out from the lane bytresetting the grouping switches G811 and (sub to any desired position.

If desired, one or more channels may be allotted more transmitting time than a less important channel by multiplying the more important channel more frequently to the contacts of selector switches So and Sb. Thus if the first channel is more important than the third channel, transmitter TI may be connected to one set .of bank contacts of selector Sa illustrated as individual to transmitter T3 when channels I2-3 or I-3 are selected by switch GSa. In this case, the transmitting'rate from transmitter TI will be increased and from T3 will be reduced when both of these channels are in operation. I

In the system described above, transmitters and printers are entered onto or closed out from the lane by the manual operation of the control switches CSa and CSb, and the grouping switches G811 and 65b. A system in which the entrance and exit of the transmitters and printers are automatically effected is shown in Figsn3 and 4 as will presently appear.

In Fig. 3 is shown the apparatus comprising the sending station C. Three tape transmitters TI, T2 and T3 are shown, each having a marking bus bar M, supplied with negative potential through the winding I95 of the polarized cutout relay CO0 and a spacing bus bar S to which positive potential is applied directly. The five tongues I96 of each transmitter are connected through five of the seven contacts I91 of one of the transfer relays TRcI, 'I'Rc2 or 'IRc3 tosegments of ring I98 comprising one channel of a multiplex distributor TDI which also has a solid ring I99 connected to the apex of the line LI. The transmitting distributor TDI is also provided with a local ring 200 which has three segments 2!, 202 and 203, and associated with it a solid ring 204 which is connected to ground.

The control apparatus for each transmitteris similar and hence only that associated with transmitter TI will be described in detail.

Associated with each of the transmitters TI, T2 and T3 is a polarized control relay CRcI, CRc2 or CRc3 respectively. .These relays are controlled by the tape being fed into the transmitters and,'

through their contacts, are instrumental in effecting the operation of one of the transfer relays TRcI to 'I'Rc'4 inclusive as described hereinafter. The tape transmitter TI has a stepping magnet SMI, one terminal of which is connected to positive potential and the other terminal of which is connected to the mid-point of the differential autostop relay DRI. The opposite terminals of the windings "205 and 208 of the relay DRI are joined through auto-stop contact 201 and relay contact 208 respectively, thence (1) through the sixth contact I91 of transfer relay TR I to local segment 20I of distributor TDI and .(2) to tongue 209 of control relay CRcI.

, The selector switch Sc is common to the control apparatus of all transmitters TI, T2 and T3 and consists of rotatable arms 2l0 to M3 inclusive which are stepped simultaneously by the stepping magnet 220 over contact bank 22I having a row of contacts individual to each arm. Arms 2! to 2" inclusive are connected to'lefthand contacts 222 and to right-hand contacts 223 of the control relay CRc3, one of which is grwnded; depending on the settings of the tongues 224 of the relaysCRcI, CRc2 and CRc3. The contacts of bank22l associated with the arms 2l0 to 2I1 inclusive are connected to windings 225 of the transfer relays TRcl to TRc4 inclusive. Contact 228 of selector Se is connected to segment 20I of the local distributor ring 200, and arm 2!8 to contacts 221 of the control relays CRcI, CRc2 and CRc3. Arm 2I9 of se- 1 lector Sc is connected to ground, and contact 228 adapted to be engaged by said arm is connected T3 have copious supplies of tape and that=the autostop contacts 201, contacts 203 of relays DRI, DB2 and DB3 are closed and tongues 229 of these relays are closed on their right-hand contacts 230. The tongues 209, 224 and 232 of the control relays CRcI, CRc2 and CRc3 are assumed to be on their left- hand contacts 233, 222 and 234 respectively; arms 2l0 to 2I9 inclusive of the selector so on the first contacts of bank 22I as shown; contacts 235 of cut-out relay COc closed to the right and brush B5 of distributor TDI is about to engage the segments of ring I98.

Transfer relay TRcI is operated by a circuit complete from the battery connected to one terminal of its winding 225 to ground on the tongue 224 of relay CRcI. This circuit may be traced through the tongues 224 of relays CRcI, CRc2 and C1903, their left-hand contacts 222, selector arm 2I6, its bank contact 233, conductor 231 and the winding 225 of relay TRcI. The operation of this relay closes its contacts I91, thereby transferring the combination of signals set up on transmitter TI by the perforated tape to the segments of ring I98 of distributor TDI. As the brush B5 passes over these segments, the signals 'are further transferred to the solid ring I93 and sent to the line LI. Since all code combinations, except the blank signal which is employed for a special purpose as hereinafter described, have at least one marking impulse, one of the tongues I96 of the transmitter TI will engage the marking bus bar M. Thus, as the brush B5, in passing over the segments of ring I98, engages one which -is connected to a-tongue I95 of transmitter TI set against the marking bus bar M, the marking battery is passed through the upper winding I of ring I98, brush B6 engages segment 20I of ring 200. The ground applied to ring 204 is connected by the brush B0.segment 2" or ring 200. conductor 238, the sixth contact I91 the transfer relay 'I'Rcl and conductor 239 to the autostop lever 240. At this point the path is divided, one branch comprising autostop contact 201 and one winding 205 of relay DRI, andthe other branch the contact 208 and the opposing winding 205, at which point it again joins the first branch. Because of the opposition of the two windings 205 and 203, the relay DRI remains unoperated. From this mid-point of the difierential relay DRI the ground is carried to one side of the stepping magnet SMI. The other side of this magnet is connected to positive potential so that the contact of brush B6 of the distributor TDI with segment 20I of'ring 200 causes the tape for transmitter T I to be stepped ahead one character.

Brush B5, as it continues, next engages segment 202, thereby applying a ground to theselector magnet 220 which advances the rotatable arm 2"; of the selector So to its second bank contact 24I. Passing on to segment 203 of the distributor TDI, the brush B6 applies a ground to winding 242 of cut-out relay COc. The other side of this winding is connected to positive potential and is so poled that the contact 235 of relay C00 is again closed to the right.

When the arms of the selector So were advanced, as described above, the ground originating at tongue 224 of the control relay CRcI was transferred by arm 2I6 to its second bank contact24l and thence to conductor 243 for theoperation of transfer relay TRc2. Thus, when next the brush B of the distributor TDI engages the contacts of ring I98, a character is sent from transmitter T2 and contact 235 of cut-out relay CO0 is opened. Subsequently the brush B6 passes over segments 20I, 202 and 203, stepping the tape of transmitter T2 ahead, advancing the selector arms 2I0 to 2I9' inclusive and reclosing contact 235 of the cut-out relay COc. A signal combination is next selected, by the engagement of arm 2I5 of selector Sc with its bank contact 244, from transmitter -T3 and sent to line LI in a manner similar to that described above. As the brushes B5 and B6 of the distributor TDI continue to revolve and arm 2I6 of the selector Sc is advanced successively over its other bank contacts 245, 246 and 241, another character from each of the transmitters TI, T2 and T3 is selected and sent to line LI.

The next stepping of the selector Sc brings the arms 2I0 to 2l8 inclusive into engagement with bank contacts 248 to 256 inclusive to which there are no connections. Hence at this time there is no transmission from any of the transmitters TI, T2 and T3. Also arm 2I9 is in engagement with its bank contact 228 which connects a ground, by way of conductor 251, to one terminal of the winding 225 of transfer relay 'I'Rc5, the other terminal of which is connected to battery thus operating this relay. This ground is also applied, by means of conductor 258 to the tongues 229 and the right-hand contacts 230 of the differential autostop relays DRI, DB2 and DR3, to one terminal of each of the windings 23I of the control relays CRcl, CRc2 and CRc3. These windings have their other terminals connected to battery and hence are energized being so poled that the tongues 209, 224 and 232 are held on their left hand contacts 233, 222 and 234 respectively. Since these tongues have been set against their left-hand contacts throughout the entire operation of the transmitting mechanism up to this point, this last event serves only as a confirmation of the settings at this time. The tongues 232 in cooperation with their lefthand contacts 234 and three of. the contacts I81 of transfer relay TRc5 apply marking potential to the first three segments of ringI98 of the distributor TDI. Twoother contacts I91 of the transfer relay 'I'Re5 apply spacing potential to the other two segments of ring'I98. Thus on the following revolution of the brush B5 a pattern signal corresponding to the transmitters that will be operating at the beginning of the next cycle of the selector Sc, in this case transmitters TI, T2 and T3, is sent to the line LI.

It should be noted that this pattern is transmitted once in every cycle of the selector Sc and,

at the receiving station D, is 'used to maintain the printers of all three channels operating, as described hereinafter. It will also appear presently that just prior to the transmission of the pattern, the tongues 209, 224 and 232 of any of the control relays CRcI, CRc2 or CRc3 associated with an entering transmitter TI, T2 or T3 are moved to their left contacts 233, 222 and 234 respectively by the application of the ground 01' arm 2I9 of the selector So to the windings 23! of relay CRcI, CRc2 and CRc3, thereby entering the transmitter onto the lane of traffic, here constituted by a multiplex channel.

More efiicient use of the lane time can be obtained by using a selector with a greater number of bank contacts in each row instead of a minimum of seven as shown. For instance, with rows of twenty-five contacts, the contacts may be divided into four groups of six contacts, each group similar to the first six contacts of switch S3, plus one contact for switching purposes as described above, and thus a greater percentage of the lane time can be utilized for the transmission of trafiic. Hereinafter, whenever reference is made to lane time, it is desired that it be construed to'mean that portion of it actually devoted to the transmission of trafilc.

As long as each of the transmitters TI, T2 and T3 is supplied with perforated tape, operation continues as described. But assume, now, that the supply of tape for one of the transmitters, for instance TI, has become exhausted. The shortening of the tape loop 259 will raise the lever 240 opening the autostop contact 201. When next the transmitter TI is associated with the lane and brush B6 engages segment 20I of ring 200, the circuit that ,is completed between the ground on ring 204 and the battery connected to the stepping magnet SMI has but one path through the differential relay DRI; namely, that comprised of contact 208 and winding 205. This condition unbalances the autostop relay allowing it to operate. Thus tongue 229 is moved to the left, breaking its connection with contact 230 and tongue 260 is engaged with arm 26I which applies a locking ground to the stepping magnet SMI and opens the contact 208 of relay DRI. Hence the pins of the transmitter TI are held withdrawn from the tape which sets all of the tongues I96 against the spacing bus bar S, and

C it provides for the elimination of transmitter TI. The absence of marking signals from this last transmission results in the contact 235 of cut-out relay COc remaining closed. Thus,'when brush B6 engages segment 20! of ring 200, a circuit is completed from the ground on ring 204 to the battery connected to winding 265 of relay CRci. This circuit includes brush B6, local segment 201., conductor 262, contact 235 of relay C00, the seventh contact I91 of relay TRci, conductor 263 and the windings 264 and 265 of relay CRcl. The winding 264 is poled to hold the tongues 209, 224 and 232 against their left contacts 233, 222 and 234 respectively, and winding 265 is oppositelypoled but winding 254 predominates. Thus, as long as brush B6 remains on segment 20L the relay CRcI is unaffected. *But as soon as brush B6 leaves segment 201, condenser 266 discharges through the winding 265 of relay CRcl moving the tongues 209, 224 and 232 to their right hand contacts 221, 223 and 261 respectively.

Now, an inspection of the tongues 224 and their associated contacts 222 and 223 of relays CRcl, CRc2 and CRc3 will disclose that the ground connected to tongue 224 of relay CRel has been transferred from arm 2I6 to arm 2| 5 of the selector Se. Also the bank contacts associated with arm 2l5 are connected alternately to conductors 243 and 268 which, in turn, are connected to windings 225 of transfer relays TRc2 and TRc3 respectively. Hence, as the brushes B5 and B6 of distributor TDI continue to revolve, the entire lane time is now divided equally between transmitters T2 and T3.

In a similar manner, either one or both of the transmitters T2 and T3 will be cut out, whenever the tape loops 259 associated with them become short enough to open their respective autostop contacts 201, by the resultantoperation of relays CRc2 and CRc3. Suppose, now, that it is desired to enter a transmitter onto the lane, for instance, the one that was just cut off, Tl. As soon as the transmitter TI is supplied with additional perforated tape, the loop 259 lengthens allowing contact 2010f the autostop relay DRI to close. But before being entered onto the lane this transmitter must wait until the arm 215 of selector Se is engaged with its bank contact 269 which connects transmitter T3 to the lane. After the transmission of a character from transmitter T3 and when brush B6 is passing over local segment 20 I, in addition to the circuit established between the ground on ring 204 and the battery 'on-thc stepping magnet SM3, another circuitis completed.'from the ground on ring '204 to the battery onsthe stepping magnet SMI.

This circuit is comprised'of brush B5, local segment 20|,conductor 210 bank contact 226 of transmitter TI is alsounlocked rendering it ready for regular operation.

When thearms of the selector Scare further advanced bringing arm 2| 9 into engagement with bank contact 228, circuits are'established, between the ground on arm 2|9 and the winding 225 of relay TRc5, and the windings 231 01 res point.

lays CRcI, CR1c2 and CRc3 as described above. It will be remembered that, when transmitter Tl was closed out of the lane previously, the tongues 209,224 and 232 of relay CRcl were set against their right hand contacts 221, 223 and 261 respectively where they have remained up to'this Hence, since the windings 23! of the control relays CRcl, CRe2 and CRc3 are poled to move the tongues 209, 224 and1232 of these relays to their left hand contacts 233, 222and 234 respectively, as indicated hereinbefore, energizing them at this time results in the movement. of the tongues of relay CRcl only, those of relays CRcZ and CRc3 already being in these positions. This movement transfers the ground on tongue 224 of relay CRICI from selector arm 2l5 back transmitters Tl, T2 and T3 with the'lane of traffic as before." Tongue 232 of relay CRcl will also furnish marking battery to the first segment of ring I98 so that, when next the brush B5 c'rosses'the segments of this ring, the new pattern signal will be transmitted to the receiving station D where a printer will be connected to the lane for he reception of signals from transmitter TI.

The transmitting apparatus is arranged so that the lane'time is always divided equally among the particular transmitters Tl, T2 and T3 that are connected to the lane. This division of'lane time among transmitters Tl, T2 and T3 and "between transmitters T2 and T3 is effected by applying a ground to arms 2l6 and 2l5 respectively of selector Sc as described above. With other positions of the tongues 224 of the relays CRcl,

1CRc2 and CRe3,as determined by the settings of the auto-stop contacts 201 of relays DRI, DB2

and DR3, the ground is applied to other o't the arms 2l0 and M1 inclusive of selector So. The ground on arm 2 l0, 2 or 21 2 willgive complete possession of the lane to either 'transmitterTl, T2 or T3 respectively. Similarly, the ground connected to arm 2|3 will' divide the lane time between transmitters TI and T2, and connected to arm 214 will elTect a division of lane time between transmitters TI and T3 If none of the trans-- mitters is connected to the lane when the armatures of relays CRcI, CRc2 and CRc3 engage their respective right hand contacts, the'ground is apa timewhen none of the transmitters'is connected to the lane. One such period in a complete cycle of operation of the selector Se is 'provided and is devoted exclusively to that function. In this embodiment of the invention, the entrance and exit of individual transmitters is automatically controlledby the tape supplied to the transmitters, and the concurrent entry of the corresponding printer or printers is effected without requiring more transmission time than that required to send a single character.

The-receiving apparatus at station D, shown in Fig. 4, consists -of a selector Sd, control relays CRdI,CRd2 and vCRd3, transfer relays TRdl to .TRd4 inclusive, cut-out relay COd, printers Pl, f P2 and P3.and the distributor RDI.

Brushes B1 and B0 of the latter are maintained in synchronism with brushes B5 and B6 of the transmitting 50 The contacts 191 of this relay connect "distributorTDl of Fig. 3 in the usual manner. Brush B1 of ceiving distributor RDI acts as the means of tra sferring the line signals from solid ring 211 to the segmented ring 212, the five segments of one channel shown corresponding to the transmitting multiplex channel shown in Fig. 3. Brush B8 connects the positive potential oi. solid ring 213 to the segments 214 to 211 inclusive of the local ring 218. The interconnections of the apparatus are substantially similar to those of corresponding apparatus at station C of Fig. 3. The printers P1, P2 and P3 are associable with the lane by five of the sevencontacts 219 of the transfer relays 'I'Rdl, TRd2 and TRd3, respectively. These transfer relays are operable by the passage of arms 280 to 286 inclusive of the selector Sd over their respective contact banks 288. The tongues 289 and contacts 290 and 291 of the control relays CRdl, CRd2 and CRd3 cooperate to apply a ground to one of the arms 280 to 286 inclusive of selector Sd for the operation of one of the transfer relays 'I'Rdl, TRd2 or TRd3. The control relays CRdl, CRd2 and CRd3 are the polarized type and are operated either by signals received from the line L1 or by local impulses from ring 218. For use in cutting ofi. any of the printers P1, P2 or P3 from thelane the polarized relay God is provided whose contact 292 is closed when its winding 293 is energized by the engagement of brush'B8 with local segment 214; and whose contact 292 is opened when its winding 294 is energized by the reception of a marking signal by one of the five selecting magnets 295 of any of the printers P1, P2 or P3.

The operation of the receiving apparatus is-as follows:

Assume that the tongues 289 of the control relays CRd1,'CRd2 and CRd3 are set against their left hand contacts 290, that arm 286 of selector Sd is in engagement with its first bank contact 296 and all other arms 280 to 285 inclusive and 281 are engaged with their respective corresponding bank contacts as shown. Also assume that the brush B8 of distributor RDI is just engaging local segment 214. A circuit is established between the ground of tongue 289 of relay CRdl and the battery on the winding 29 1 of transfer relay TRdl comprised of the tongues 289 and left hand contacts 290 of control relays CRdl, CRd2 and CRd3, conductor 298, arm 286 and bank contact 296 of selector Sd, conductor 299 and winding 291 of relay TRdl. With this relay operated, its contacts 219 are closed connecting the selecting magnets 295 of the printer P1 to the segments of ring 212, and the printing magnet 301 with the local segment 215 of ring 218. The passage of brush B8 over segment 214 completes a circuit from battery on ring 213 over conductor 302, through winding 293 of cut-out. relay God to ground, this winding being poled to close the contact 292. Brush B1 then passes I over the five segments of ring 212 transferring the character signals being received from line L1 to the selecting magnets 295 of printer P1. Common to one'terminal of all selecting magnets 295 of all printers P1, P2 and P3 is positive potential supplied through the winding 294 of relay COd. Hence, only when marking, or negative, battery is applied to a selecting magnet 295 from the distributor RDI is it and the winding 294 of relay COd energized, the latter being poled to open the contact 292. Since all code combinations, except the blank signal, have at least one marking impulse, at least one of the selecting magnets 295 ofprinter-Pl and the winding 294 of relay 0011 will be energized whenever any character is received. When brush B1 has passed over the last of the five segments of ring 212, brush B8, en-

gages local segment 215 of ring218. The print-' ing magnet 301, with one terminal grounded, and with its other terminal being supplied with battery from ring 213 by brush B8, segment215, conductor 303 and the sixth contact 219 of relay TRdl is energized completing the printing of the character. Moving along, the brush B8 passes over segment 216 with no result at this time, and on to segment 211 from which the battery of ring 213 is transferred by conductor 304 to the stepping magnet 305 of the selector Sd and thereby advancing the arms 280 to 281 inclusive of selector Sd to their second bank contacts.

With arm 289 of selector Sd connected by its bank contact 306 to conductor 301, the transfer relay TRd2 is operated. Thus the next character received by the distributor RDI is directed to printer P2.

ated, the groundon selector arm 281 being applied by contact 314 and conductor 315 to the winding 291 of relay TRd4. The closing of the contacts 219 of this relay connects the windings 316 and 311 of control relays CRdl, CRd2 and CRd3-with the first three segments respectively of ring 212' of the receiving distributor RDI. Thus, when the pattern is received on the next revolution of p the brushes B1 and B8, it is used to set the tongues 289 of relays CRdl, CRd2 and CRd3 to correspond with similar ones at the transmitting station C of Fig. 3. In. this case all marking, or negative, signals are received as described above in connection with Fig. 3 because all printers P1, P2 and P3 are to remain in operation. Since the same results are produced on all control relays CRdI, CRd2 and CRd3, the actionof only relay CRdl will be described. The windings 316 and 311 are oppositely poled, but winding 316 pre dominates and winding 311 is shunted with the condenser 318. Negative potential applied to winding 316 by the engagement of brush B1 with the first segment of ring 212 moves'the tongue 289 to its right hand contact 291 and upon the removal of the battery, when brush B1 has left the segment, the discharge of the condenser 318 through winding 311 moves the tongue 289 back to its left hand contact 290. Thus, when the selector arm 286 is again stepped to its bank contact 296, the receiving apparatus is set to operate as before which it does until the blank signal is received on printer P1.

It willbe remembered from the description of Fig. 3 that just prior to being closed out of the lane, a blank (or all spacing) signal was sent from transmitter T1. With operation of the receiving apparatus of Fig. 4 proceeding as described above, this blank signal is received on printer P1 when connected to the lane by the contacts 219 of relay TRdl in one of its regular turns. Since all signals are spacing, or of positive potential, none of the selecting magnets 295 of printer P1 nor the winding 294 of the cutout relay God are energized and consequently contact 282 of the latter relay remains closed. The engagement of the brush Bl with local segment 21! produces no result because the blank signal is automatically deleted from printer PI. The passage of brush Bl over segment 21 at this time completes a circuit, comprised of conductor Ill, contact 202 of relay COd, conductor "I, the seventh contact 219 of relay 'IRdl and conductor 32!, to winding ll! of control relay CRdl thereby applying positive potential to the windings iii and ill of this relay. This results in themove nent of the tongue 2" to its right hand contact "I as soon as brush B8 leaves segment 21. II! and contacts 2" and ill of the relays CRdl, CR4 and CRd3 now will show the ground of tongue 2 of relay CRdI applied to selector arm III, the bank contacts associated with which are connected alternately to transfer relays TRdI and W3. Hence with-this new arrangement, only printers P2 and P3 are connected to the lane.

But when, subsequently during the switching period, the transmitter Tl of Fig. 3 is again entered onto the lane, and the original pattern sent to the receiving "station D of Fig. 4, the tongue 2" of relayCRdl is once more set on its left hand contact 2, thereby providing for the connection of printer Pl to the lane. Thus the manner in which the entrance and exit of the receiving printers to and from the lane concurrently with the entrance and exit of the transmitters is effected by line signals under the control of the corresponding transmitting apparatus will be apparent.

While only three transmitters and three receiving printers have been considered in the foregoing descriptions, it should be understood that this invention provides for a communication system which is not so limited but rather, one that can be expanded to include any desired number of transmitters and printers operating over a single lane of traflic, each transmitter having the equivalent of a direct wire connection with its associated printer. While telegraph transmitters and printers have been mentioned, any desired sending and receiving or recording devices may be employed. Although the actual transmitters in a telegraph system are preferably located in a central station, the points of origin of the traific may be in widely separated sub-stations having individual connections with the central station where it is stored by some well known apparatus. Similarly, the receiving recorders may be located in outlying sub-stations having extended channel connections to the central station. Also it will be evident to anyone skilled in the art that the embodiments of this invention described in these specifications are but two of many forms in which the novel features may be incorporated, and that lanes of trailic other than a multiplex channel may be used as the transmission medium. Consequently, no limitations on the invention are contemplated other than those imposed by the scope of the appended claims.

' What is claimed is:

1. In a communication system, a lane'of tramc, a plurality of transmitting devices, means for operating a variable number of said devices to transmit over the lane of traflic and for dividing a predetermined part of the lane time between operating transmitting devices, said means including a sequencing device having a plurality of operative positions and connected to eflect trans- An examination of the tongues mission from one of the transmitting devices in each of said positions, means for advancing said sequencing device from one position to another, and an auxiliary switch means for predetermining the transmitting device to be rendered operative in each position of said sequencing device.

2. 'In a communication system, a lane of tramc, a plurality of transmitting devices, means for operating a variable number oi said devices to transmit over the lane of trafllc and for dividing step-by-step switch.

3. In a communication system, a lane of tramc, a plurality of transmitting device's, means for operating a variable number of said devices to transmit over the lane of traflic and for dividing a predetermined part of the lane time between operating transmitting devices, said means including a step-by-step switch controlling the connection of said transmitting devices to the lane of traflic, means for operating said step-by-step switch after each transmitting cycle, and means including an auxiliary multiposition switch for predetermining the transmitter or transmitters which may be connected to the lane of trailic by said step-by-step switch.

4. In a telegraph system, a lane of trafllc, a plurality of transmitting channels, means for operating a variable number of said channels to transmit over the lane of traflic and for dividing the lane time between the operating channels, pattern signal transmitting means for transmitting signals over the lane of traflic to indicate a desired change in the allocation of channels and for transmitting other signals to confirm channels which are to remain connected or disconnected, and means for rendering said pattern signal transmitting means operative at predetermined intervals.

5. In a communication system, a lane of trailic,

a plurality of sources of permutation code signals, means for operating a variable number of said sources to transmit signals over the lane of trafilc and for dividing a predetermined part of the lane time between operating sources, means for sending a controlling signal over the lane of traflic consisting of code impulses, each impulse representing one of said sources of signals, and means responsive to said controlling signal for entering a receiving device corresponding to a source of signals seeking entry onto the lane of traflic. 6. In a communication system, a lane of traflic, a plurality of communication channels, means for operating a variable number of channels over the lane of traflic and for dividing the lane time between operating channels, means for periodically transmitting a channel pattern signal consisting of an impulse corresponding to each of said plurality of channels to permit the entry of an additional channel, and devices at the receiving end'of said lane of trailic responsive to said pattern signal.

7. In a communication system, a lane of tramc, a,plurality of communication channels, means for operating a variable number of said channels over the lane of trafllc and for dividing the lane time between operating channels, and means for transmitting a channel pattern signal whenever one of said channels becomes inoperative to prepare for the exit of said inoperative channel and means responsive to said signal to disconnect said channel.

8. In a communication system, a lane 01 trafllc, a plurality of communication channels, means for operating a variable number of said channels over the lane of traflic and for dividing the lane time between operating channels, and means for transmitting a channel pattern signal consisting of impulses corresponding to the operative or non-operative condition of a group of said channels whenever a change of status is desired on one of said channels.

9. In a telegraph system, a lane of trafllc, a plurality of code telegraph transmitters, and means for operating a variable number of said transmitters to transmit message characters over the lane of trafllc and for dividing a predetermined part of the lane time between operating transmitters, said lane of traflic including a synchronous multiplex channel having synchronous distributors at the sending and receiving ends thereof and said means including switches arranged to connect the respective code contacts of the transmitters directly to the segments of the transmitting distributor individually during the time each transmitter has access to the multiplex channel.

10. In a telegraph system, a lane of traflic, a plurality of communication channels, means for operating a variable number of said channels over said lane of trafiic, a control or auxiliary signalling channel, and signalling means for operating said control channel over said lane, said signalling means including a two-position switch and an indicator or recorder responsive to said switch positions.

11. In a telegraph system, a lane of traflic, a plurality of tape transmitters, a selecting means having multiple contacts for connecting said transmitters with said lane, and manual means for arranging operative ones of said transmitters in groups and for connecting said operative transmitters to successive contacts of said selecting means.

12. In a telegraph system, a lane of trailic, a plurality of sources of permutation code intelligence signals, selecting means for automatically transferring from said sources said intelligence signals to said lane of trafiic, and means including a multi-position manual switch for associating any one or any group of said sources with said selecting means.

13. In a telegraph system, a lane oftrafllc, a plurality of transmitters having tape controlled code contacts, means for selecting any of said transmitters individually or in groups of two or more, said means comprising a manually operated multi-stage switch, each stage comprising a contact wiper and a plurality of contacts, en-

gaged thereby, said contacts being connected to said transmitters to be operated over said lane with said switch, said switch having one stage individual to each code contact of a transmitter, each of said stages comprising a plurality of stationary contacts associated with corresponding code contacts of said transmitters and a movable contacting member automatically operable simultaneously with corresponding contacting members of other stages to successively engage said stationary contacts for transference of said code contact to said lane of traffic, and means including said selector switch to equally divide substantially the full lane time between erating transmitters.

15. In a telegraph system, a lane of tramc, a

lecting switch for operating a variable number of said transmitters over said lane of traflic, and a manually controlled means for arresting said selecting switch at a predetermined point and modifying the electrical condition of the lane to indicate the stopping of the selecting switch.

16, In a telegraph system, a lane of traflic, a

plurality of communication channels, sending and receiving sequencing means for operating a variable number of said channels over said lane, manual means for arresting said sending sequencing means and modifying the electrical condition of said lane, and means responsive to said electrical condition for arresting said receiving sequencing means. i

17. In an expanding channel telegraph system, a lane of trafllc, a plurality of communication channels, sending and receiving selecting devices for operating a variable number of said channels over said lane and for dividing the same predetermined part of the lane time among the operating channels irrespective of the number of operating channels, means for applying an electrical condition to said lane, and means responsive to said condition to synchronize said selecting devices.

l8. In'a telegraph system, a lane of ,trafiic, a plurality ofcommunication channels, means for operating a variable number of said channels over said lane and for dividing a predetermined part of the lane time among the operating channels, said means including sequencing devices having a plurality of operative positions and connected to efiect transmission on one of said operative channels in each of said positions, signal storage means constituting a source of signals for said channels, and means responsive to said storage means to eflect a re-allocation of the positionsof said sequencing devices when the operative or inoperative status of one or more of said channels changes.

19. In a telegraph system, a lane of traflic, a plurality of communication channels, means for operating a variable number of said channels over said lane, saidmeans including a sequencing device having a plurality of operative positions, there being one or more of said positions connected to effect the operation of each of said operative channels, signal storage means constituting a source of signals for said channels, and means responsive to said storage means to reallocate the positions of an inoperative channel to the remaining ones of said operative channels at any time during a cycle of said sequencing device. a

20. In a telegraph system, a lane of'tramc, a

plurality of communication channels, means for successively connecting a variable number of the opplurality of transmitters, means including a sesaid channels with said lane for operation thereover, signal storage means constituting a source of signals for said channels, and means responsive to-said storage means at predetermined intervals to efiect the entry of one or more additional channels onto said lane.

21. In a telegraph system, a synchronous multiplex system including sending and receiving distributors, a plurality of communication channels comprising code sending and receiving devices at opposite ends of said multiplex system, means including step-by-step switches at opposite ends of said system for connecting the code instrumentalities of the respective sending and receiving devices to the multiplex distributors, and means including said distributors for operating saidswitches in synchronism.

22. In a telegraph system, a lane of traffic, a plurality of communication channels, a multiposition switch arranged to render any of said channels operative to send over said lane either individually or in groups of two or more, and

means whereby said channel transmission is continued in each of the respective positions of said switch irrespective of the grouping of the channels.

23. In a telegraph system, a lane of traffic, a

plurality of communication channels, means for operating a variable number of said channels over the lane of trafiic and for dividing the lane time among the operating channels, means operative periodically for transmitting signals over the lane of traific to identify operating channel transmitters, and means responsive to said signals to indicate the identity of said operating transmitters.

24. In a telegraph' system, a lane of trafiic, a plurality of communication channels, means for operating a variable number of said channels over the lane of traflic and for dividing the lane time among the operating channels, means operative periodically to indicate the operative condition of the channel transmitters and for transmitting'pattern signals over the lane characteristic of said condition, andmeans responsive to said signals to control the operativeness of the channel receivers.

25. In a telegraph system, a lane of traffic, a plurality of communication channels, cyclic means for operating a variable number of said channels over the lane of traflic and for dividing the lane time among the operating channels, means immediately responsive to a change of status of any of said channels to prepare for reallocation of the lane time, and means for effecting said re-allocation only at predetermined points in the cycle of operation of said first named means.

26. In an expanding channel telegraph system, a lane of traffic, a plurality of communication channels, sending and receiving selecting devices for operating a variable number of said channels over said lane and for dividing a predetermined part of the lane time among operating channels, means for synchronizing said devices comprising a manually controlled relay having contacts to arrest one of said devices in a "stop position and for successively transmitting over said lane signals indicative of said stop 'position, a second relay having contacts operative to arrest the other of said devices in its stop position, and circuit arrangements to by one of said signals.

28. In a telegraph system, a lane of trafiic, a plurality of communication channels each comprising code sending and receiving devices at opposite ends of said lane of trafllc, certain of said channels being idle at times, means including a step-by-step switch at one end of said system for successively connecting the code-instrumentalities of different sending devices to said lane of traffic and means for testing at intervals 'the busy or idle condition of all of said channels.

29. In a telegraph system, a lane of trafllc, a plurality of communication channels each comprisingcode sending and receiving devices at opposite ends of said lane of traffic, certain of said channels being idle at times, means for successively associating said channels with the lane of traffic in a manner to devote the lane time principally to the busy channels, said means including stepping switches at opposite ends of the system, said switches having stepping magnets and contact banks containing separate contacts representing separate ones of said channels, and

means for concurrently energizing the stepping magnets of both of said switches.

30. In a telegraph system, a lane of traffic, a

plurality of communication channels each comprising code sending and receiving devices at cpposite ends of said lane of trafiic, certain of said channels being idle at times, means for succes: sively associating said channels with the lane of trafllc in a manner to devote the lane time principally to the busy channels, said means including stepping switches at opposite ends of the system, said switches having stepping magnets and contact banks containing separate contacts representing separate ones of said channels and means for concurrently energizing thestepping magnets of both switches, and means including said switches for testing at intervals the busy or idle condition of all of said channels.

PHILO HOLCOMB, JR.

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