US2339804A - Multiplex telegraph system - Google Patents

Description

Jan. 25, 1944.

| POTTS MULTIPLEX TELEGRAPH SYSTEM 1941 4 Sheets-Sheet 1 Filed Jan.

' INVENTOR. LOUIS M. POTTS ATTORNEY.

Jan. 25, 1944. -rs 2,339,804

MULTIPLEX TELEGRAPH SYS TEM Filed Jan. 18, 1941 4 Sheets-Sheet 2 495 INVENTOR.

LOUIS M. POTTS I TTORNEY.

L. M. POTTS Jan. 25, 1944.

MULTIPLEX TELEGRAPH SYSTEM I Filed Jan. 18, 1941 4 Sheets-Sheet 3 INVENTOR. LOUIS M. POTTS ATTORNEY.

Jan. 25, 1944. L. PQTTS MULTIPLEX TELEGRAPH SYSTEM 4- Sheets-Sheet 4 Filed Jan. 18, 1941 FA IJ ad $3 ME? w 3 $2 =56 4 5 2 m M v 5 O5 5 H3 58 9 0 6 4 4 w 3 4 3 4 4 4 4 4 FIG. l3

STOP START I STOP START 5 STOP STOP START START 5 STOP INVENTOR.

LOUIS M. POTTS STOP START A ORNEY.

Patented Jan. 25, 194 4 mire s'rras MULTIPLEX TELEGRAPH" SYSTEM' Louis M. Potts, Evanston, Ill., assignor-to Tele type Corporation, ChicagoJlL, a corporationof.

Delaware Application January 18, 1941, Serial No; 374,991

20 Claims. ('01. 178-53.!)

This invention relates to printing telegraph systems and more particularly to systems operated selectively according to the principles of simplex or multiplex telegraphy.

The principal object of this invention is to provide a synchronous multiplex telegraph system in which each channel of the system is brought into proper phase relation by the act of establishing synchronism.

Another object of this invention is to provide a flexible telegraph system capable of either startstop simplex operation or synchronous multiplex operation and readily convertible from one mode of operation to the other.

Another object of this invention is to provide a telegraph system comprising a main channel and a branch circuit normally conditioned for start- 7 stop simplex operation and a means to condition the system for synchronous multiplex operation by the addition of another branch circuit to the system.

A further object of this invention is to provide means to convert from simplex operation to synchronous multiplex operation and vice versa without interrupting transmission over the branch circuit and main channel normally conditioned for simplex operation.

A still further object of this invention isto provide proper phasing and synchronizing of the telegraph apparatus to establish and maintain synchronous multiplex operation in the system.

This invention features a main channel with which a branch circuit is normally directly connected for simplex operation but with which another branch circuit may be connected through a cuit's" to the main channel comprises a pair of regenerative repeater-s each of which inserts a delayof halfia signal impulse and apair of polar relays conditioned by' the transmitter and the distributor jointly to include one or both regenerative repeaters in the-branch circuit: and tomsert a delay of eitherone half impulse or two hahi impulses.

In the first modification of the-invention a cam proper phase. with the operation of the multiplex distributor contacts. I

A further feature of this invention residesin the provision of a circuit, energized" at one end of .the main channel, to place into operation and at the same timeto properly phase thedistributors at each terminal of the main channel prepar'a tory to establishing synchronous multiplex 013- I erati'on.

distributor for synchronous multiplex operation. 1

When conditioned for synchronous multiplex operation, the branch circuits at the sending and receiving terminals of the main channel are connected therewith through regularly operated contacts included in synchronous distributors, which distributors operate in synchronism and in phase with one another. In each transmission branch circuit there is provided a start-stop permutation code transmitter operable at random and signal repeating mechanism capable of generating two identical sets of signals which are out of phase with one another. There is also provided means which under the dual control or" the transmitter and 'a' transmission phasing cam included in the multiplex distributor selects and applies to the main channel, impulse by impulse, that set of signals which is in suitable phase relation with the multiplex distributor contacts, inserting a variable delay in the transmission circuit due to the operation of the repeating mechanism.

f In the first embodiment of the invention the means to control the delay in the transmission circuit and to properly phase the repetition of transmitted signals to the operation of the distributor contacts which connect the branch cir- As'a still further feature this invention pro? vides a relay circuit energized under the-dual control of the distributor mechanism and the transmitted signals in the normal simplex circuit to establish synchronous multiplex operation or to return to simplex, operation from synchronous multiplex operation without interfering with, transmission over the branch circuit normally connected with the main, channel.v

This invention further features a carrier telegraph system in which each branch channel is provided with distributing mechanism operable to multiply the number of communication; chan nels available in the carrier system.

More specifically, the invention in one applica tion embodies a plurality of main channels to each of which is. normally connected for simplex operation .thereover, abranch'circuit and to each In order to avoid interrupting the simplex operation and mutilating a signal combination, a relay circuit operates to establish synchronouscause it is normally conditioned for simplex operation. Reference to Figs. 1 and 2 will show that conductor l is normally connected directly to conductor 3 of main channel C through the contacts l1 at relay 55 completing a simplex communication path from a substation II to a main channel C. Main channel C is shown as multiplex operation only when the distributors are operating in phase with one another and at synchronous speed and in proper phase relation with the transmitter operating at random in the normal simplex circuit. v

The transmitter in each branch circuit when the system is connected for multiplex operation operates at random but the branch circuits are regularlyconnected with the main channel and signal repeating mechanism is provided in each branch cirouit to generate signals in a suitable phase relation with the operation of the multiplex distributor contacts. The repeating mechanism is controlled jointly by the phase of the incomingsignals and a transmitting phasing cam in the multiplex distributor to phase the output of the repeater mechanism with the operation of the multiplex distributor contacts and to maintain this relation for acomplete set of signal combinations.

, A more complete understanding of the invention may be had from the following detailed description to be interpreted in the light of the annexed drawings wherein:

Fig. 1 shows an assembly of substations, repeater mechanisms, repeater controlling relays and associated circuits for switching the repeating mechanism into and out of service;

Fig. 2 illustrates two central stations including circuits and distributor mechanisms for completing communication channels. from the substations of Fig. 1 to substations also designated in Fig. 2;"

.Fig.-'3'shows a modification of the equipment of Fig. Y1, employing mechanical relays for controlling the repeaters; I'

Fig. 4 shows a further modification of: the

part of a carrier telegraph system including a carrier conductor 51 to which the basic circuit is extended over conductor 3 and, therefore, it is proper to call conductor 3 an extension conductor to which basic circuit A is normally connected.

Branch circuit B is termed an additive circuit because it is normally out of the telegraph system but may be added thereto. Conductor 2 of circuit B, for example, is normally interrupted at the outer right hand armature of relay 55 and when relay 55 is energized, in a manner tobe hereinafter described, circuit B is added to extension conductor 3 in alternation with basic channel I through a distributor 2| and its cam controlled contacts.

Conductors 5 and 6 also extend from Fig. 1 to Fig. 2 and are included in operating circuits of the mechanism associated with the circuits above-mentioned. Signaling conductor 9 also extends from Fig. 1 to Fig. 2 and is utilized to control lamps associated with circuit B.

Substation ll includes a transmitter l2 which may be tape controlled or a direct keyboard type, 'a home recorder l3 and a receiving recorder l4. Other substations included in the system are similar. A regenerative repeater is symbolized in Fig. 1 at [5 and may be of the type illustrated and described in United States Patent No. 2,105,173 issued to W. J. Zenner et al. and is characterized by the fact that code signals are repeated therefrom impulseby impulse with a time delay of about one-half of an impulse period with respect to received signals. Although a particular type of regenerative repeater is here disclosed, it is to be understood that the type described is chosen for this embodiment of invention only and that any desired regenerative repeater may be employed. Storage repeater I6 and all other repeaters having the same symbol are the same as repeater l5. Polar and neutral relays, tuned relays, and unidirectional valves may be recognized by their well-known symbols.

' Figs.7 to 12 inclusive show mechanical dein Figs. .7 through 11.

FIRST EMBODIMENT Figs; 1 and 2 when combined present complete circuits" illustrating one embodiment of a system employing this invention; In general, conductors l andZ extend from Fig. 1 to Fig. 2 and form a partof branch circuits A and B respectively. Branch circuit Ais termed.- a- "basic" circuit be- At 20 is represented a central oflice through which substations are connected for inter-communication. A transmitting distributor 2| is located at the central oii'ice and is driven from a speed controlled motor 28 through gearing 29. The distributor includes a shaft 22 carrying cams 23, 24, and 21 operative to establish and maintain synchronous operation over main channel C, in a manner to be described hereinafter.

A distant central ofiice is designated 30 and it is equipped with a receiving distributor 3| which comprises a shaft 32 driven by speed controlled motor 38 through gearing 39. Cams 33, 34, 36, and 31 carried by shaft 32 operate in synchronism with cams on distributor shaft 22 during multiplex operation.

Orientation between motor phasing cam 31 and distributor cams 33 and 34 is provided by hub ll on cam 31, the hub being adjustably fixed to shaft 32 by set screw 42. Rectangles 43 and 44 represent regenerative repeaters identical in construction with repeater l5 and controlled by non-biased, polar relays.

The description and mode of operation of the system illustrated in Figs. 1 and 2 will be set forth first for its normal condition of operation,

transmission circuit.

that is, simplex operation, and then for an alternative condition, such as synchronous multiplex operation. Accordingly, the normal operation wherein the distributors 2I and 3|. are idle and wherein only the basic circuit A is connected for a simplex telegraph operation, is as follows:

Permutation code start-stop signals for basic circuit A are generated by transmitter I2 at substation I I and are transmitted over line conductor 5I to regenerative repeater I5, whence regenerated impulses ilow through conductor 52, armature and lower contacts of polar relay 53, to storage repeater IS, the twice repeated impulses flowing thence through conductor I, contacts I? of unoperated relay 55 and extension conductor 3 to the winding of polar line relay 5%.

A source of alternating current, 500 cycle alternating current for example, is connected to the upper contacts of polar relay 55 and. is adapted to be applied to carrier conductor 57 through the armature of the. relay 56. Accordingly, as relay 56 is actuated in response to signal impulses received over extension conductor 3 from transmitter II, pulses of 500 cycle alternating current are placed on carrier conductor 51 and thus the signal impulses are transmitted over the carrier.

The carrier conductor 57 extends the transmission circuit through hybrid coil $3 into a duplex carrier transmission circuit GI, equipped with echo suppressing networks 82. Through a similar hybrid coil t l the. signals are transmitted from duplex circuit Iii into the carrier conductor 55 to tuned relay 65 which is characterized by the fact that it is responsive only to 500 cycle current impulses. in the form of direct currents to polar relay 65 which repeats like direct current signal impulses through extension conductor 6?, conductor to, outer contacts of unoperated relay 89 and regenerative repeater 43 to line conductor 'II and to receiving recorder 12 of substatio 13.

Transmission in the reverse direction between substations I3 and II is eilected, by transmitter 74 of substation l3, duplicates of regenerative repeater I5, storage repeater I5 and transmitter distributor 2! represented by rectangle l5, duplex carrier circuit ii, coils $3 and E4, duplicates of relay 65, distributor 3t and repeater 43 repre sented by rectangle (H, and line conductor 82 to receiving recorder 54 of substation It,

Through thecircuits outlined above, substations It and i3 normally are maintained in communication by means of carrier conductors 45 and 5'1 and extension conductors 3 and 5'5. Also,

each extension conductor extending the transmission circuit to the carrier channel has associated with it only one transmitter, the association being over a basic circuit, such as basic circuit A,

associated with extension conductor 3. In other words, in this normal condition each transmitter which is connected to the carrier channel, is connected therewith over a simplex circuit.

The above described operation is predicated upon the idle position of distributor 2i illustrated in Fig. 2, which conditioned the armatures of relays 53 and 83 against their lower contacts and included both repeaters I5 and it in the Vfhcn distributor 2i is: disconnected from extension conductorv 3 with its cams displaced 180 degrees from the illustrated position, the normal, simplex transmission circult is direct to channel I from regenerative repeater I5 because in that position of the distributor ZI. the armatures. of relays 53 and s3 rest against their upper contacts and break the cir- Relay 55 repeats the signal impulses 1 .cuit to repeater I6" at. the armature of relay v53. In addition, there is completed. from negative battery over a circuit including the armature and upper contacts of relay 83 and repeater I6, a holding circuit which holds repeater I6 inoperative so long as the armatures of relays 53 and 83 remain against their upper contacts. Except for the omission of the repeater I5, the transmission circuit is identical with that previously described.

The normal transmission, circuit described above, whether it includes one or .both of the regenerator repeaters, interconnects substations II and 13 for communication over a. simplex circuit.

With the communication circuit of the system in this condition, additive circuit B is inoperative since conductor 2 terminates at the outer right hand contacts of relay 55 which are open.

The circuits and their mode of operation for the alternate condition of the system disclosed in Figs. 1 and 2 will now be described. In this a1- ternate condition the previously defined additive circuit is included in the communication system along with the basic circuit.

To initiate the operation of additive circuit B and thus establish the alternate condition, manual key III is closed momentarily to energize relays II2 and H3 over an obvious circuit. Relay I I2 closes its holding contact to form an obvious holding circuit for relays I I2 and H3. Relay II3 operates and connects power conductors II4 to the motor 28 thus placing the motor 28 in oper ation to drive the distributor shaft 22. 1

In its unoperated condition the relay H2 through its outer right hand contacts has maintained conductor I 2| connected to earlier conductor 5! thus supplying an unbroken 1600-cycle current to the tuned relay I22 to supply current of positive polarity to polar relays I 23 and, I24

and held open the energizing circuit of motorcontrol relay I25 at the lower contacts of relay I23.

Upon being energized, through the operation of key II I, relay I 52 interrupts the supply of 1600 cycle alternating current at its outer right hand contacts but that supply is maintained to carrier conductor 51 through controlled contacts I26 at cam 21. However, as motor 28 drives shaft 22, cam 2'! breaks the supply circuit interrupting the 1600 cycle alternating current and, consequently, releasing tuned relay I22 whose armature then applies negative battery to the circuit of relays I23 and I24. Having thus changed the polarity of polar relays I23 and I24, their armatures are conditioned against their lower contacts and an energizing circuit is thereby completed for slowto-release relay I25 including the armature and lower contacts of relay I23. Relay I25 draws up its armature completing an obvious circuit which operates relay I2! and connects power conductors I28 to motor 38 and starts the motor to drive shaft 32.

As motor 28 increases its speed, cam 21 through its controlled contacts I25 supplies pulses of 1600 cycle alternating current from conductor I2! to tuned relay I 22 which responsively supplies direct currents of alternatin polarity to relays I23 and I24 to cause their armatures to vibrate. That is, when the 1600 cycle current is flowing, relay I22 operates and applies positive potential to the circuit of relays I23 and I24 conditioning their armatures against their upper contacts; but when that 1690 cycle current is interrupted through the rotation of cam 21, armature of relay I22 applies: negative battery to the relays I23 and I24 to move their armatures against their -lower contacts. Relay I25 is a 'slow-to-release relay to hold the power circuit to motor 38 closed through the armature of relay I21 when the armatureof relay I23 moves to its upper contacts and thus assure continuous operation of the motor 38.

In addition to controlling the supply of power to motor 38 through relay I21, the-circuit of the 1600 cycle alternating current also functions as a; synchronizing circuit to control the speed of motor 38. As explained above, the rotation of cam 21 causes the armature of relay I24 to vibrate and these vibrations are employed in conjunction with a pair of cam controlled contacts I3I and I32, controlled by cam 31, to apply a 'shunt across an armature resistance I33 to govern the motor speed. The speed of motor 38 is decreased when resistance I33 is in the armature circuit and accordingly, in order to regulate the -rnotor speeed, it is only necessary to control the length of the period during which resistance I33 period for resistance I33 in each position of the farmature of relay I24. Should motor 38 tend to increase in speed, cam controlled contacts I 3| and I32 would open the shunt circuit earlier, shortening the shunted period. of resistance I33 and decreasing the motor speed. On the other hand, if motor 38 should tend to lag, the cam 31 would not open the shunt circuit until a later instant in the cycle, elongating the shunt period *and increasing the motor speed. In United "States Patent No. 726,750 issued to L. M. Potts 'on April 28, 1903, there is disclosed and fully explained such a synchronizing system and reference may be had to that patent for a more complete disclosure of the principles of such a .system.

In'addition to synchronizing motors 28 and 38, relay I24 and contacts I3I, I32 controlled by cam 31 assure the proper phasing of the distributors 2I and 3I since there is only one position in which vshaft 22 can come into synchronism with shaft "32.

Since in the particular embodiment of the invention under consideration the alternate condition contemplates synchronous multiplex operation, it is necessary to defer the establishment of the alternate condition until distributor motors 28 and 38 are operating synchronously, and for the accomplishment of this result, means is provided, as will presently appear, to establish synchronous multiplex operation under the control of both distributor motors.

There is provided at central station 28 a plurality' of relays, such as 54, one of which is associated with each extension conductor and which must be operated to convert the extension'con- "ductor from simplex to multiplex operation. The circuit for these relays is closed by sIow-to-operate relay I36 when motor 28 has attained a predetermined'speed. The energizing circuit for relay I36 includes the inner right hand armature of relay H2, secondary of transformer I31, and 'rectifier I38. Th primary of transformer'l31 is in a tuned circuit to which alternating current 'is supplied through contacts I39 actuated by cam 21. Although there will be an alternating current flowing through transformer I31 as the motor 28 comes up to speed, relay I36 is not operated but only when the current of greater intensity which traverses the tuned circuit when the motor is at synchronous speed and voltage of resonant frequency is applied to the tuned circuit. Since relay I36 is slow to operate, it will not actuate until the motor 28 attains and. holds its synchronous speed. When relay I36 operates, the circuit including relay 54 and others (not shown) for the remaining communication channels of the system, is completed, thus operating relay 54 preparatory to connecting basic circuit A and additive circuit B to extension conductor 3 through cam controlled contacts I52 and I51.

In each basic circuit there is provided, as already explained, a start-stop permutation code transmitter, such as transmitter I2, which is operable at random and which may be transmittin at the time key III is depressed to convert the system from its normal simplex operation to synchronous multiplex operation and it is possible, if no preventive mechanism is provided, to establish the synchronous multiplex operation during the transmission of a character signal over the normal simplex channel and mutilate a signal impulse. Accordingly, a companion relay 55 is associated with each relay 54 to prevent such signal mutilation and maintain communication over the basic circuit even though the system is converted to multiplex operation. Continuing the description of extension conductor 3, basic circuit A, and additive circuit B for illustrative purposes, the operation of the companion relay 55 is as follows:

Relay 55 is a three-winding relay wherein the middle and right-hand windings energize the relay initially and the left-hand winding is a hold ing winding. The circuits for the energizing windings of relay 55 are: ground, cam controlled contact at I5I, polar relays 53 and 83, cam controlled contact at H9, conductor 5, cam controlled contact I53 to either line I29, armature I68 of relay 54, right-hand winding of relay 55 through a suitable cam opens its cam controlled contacts and retains them open until the receipt of the stop impulse.

Relay I36 in addition to completing the circuit to relay 54, supplies the ground for the obvious holding circuit of relay 55 when the relay is energized including the left-hand winding, contact and inner left-hand armature of the relay 55. When relay 54 operates in response to the actuation of relay I36 by the distributor 21 rotating at the desired speed, armatures I60 and I6I are attracted rendering transmission phasing cam 24 effective to control the circuits of the energizing windings of relay 55. If at thi instant no signal is being transmitted over the basic circuit A in the normal simplex circuit, the ciring and inner left-hand armature, complete an obvious circuit over line 9 and the outer left-hand armature of relay 55 for slow-to-operate signaling relay I45, and connect basic circuit A and adaerator diti've circuit B through the right hand armatures ofrelay 55 to cam controlled contacts I52 and I51, respectively, thus establishing the synchronous multiplex operation.

If at the time relay 54 draws up there is a signal being transmitted over the basic circuit, the energizing circuit for relay 55 Will be inter rup'ted at either cam controlled contact or H9 and this condition will prevail until th en tire signal combination has been repeated to extension conductor 3. Shortly after the stop impulse is set up the repeater for transmission, the circuit to relay 55 will again be completed at the cam controlled contacts [5| and H9 and relay 55 will be energized to establish the -'multiplei; condition as described above. The circuit, of relay 55, therefore, controlled jointly by the signaling condition of the basic circuit and the distributor mechanism delays establishing the multiplex operation until the stop impulse or no ignal impulse is being transmitted over the basic circuit. This assures continuity of transmission over the basic circuit and permits establishing synchronous multiplex operation without mutilating signals in the process of transmission over thebasic circuit. 7

At central station 39, a plurality of relays 69 similar to relay 54 is provided, one for each extension conductor 61, and this plurality of relays is operative to condition the receiving extension conductors for multiplex telegraphy through the distributor cams. The circuit of relay 59 is under the dual control of relay M! and tuned transformer 143. At I48 there is represented a tuned transformer and an associated rectifier to control relay MI in a manner identical to that described in connection with relay i345. The alternating current in this instance is supplied through the armature of relay [2'3 and its frequency is determined by the speed of 'motor '28 through cam 2'1 and its controlled contacts I26 which supply the pulses for relay I22 and consequently relay I23. When motor 28 is at synchronous speed, the frequency of this alternating current is the resonant frequency for that described for the operation of relay ['35 through contact 189. Accordingly, it follows that both 'moto'rs 2'8 and "38 must attain a predetermined speed, preferably synchronous speed,

as a condition precedent to the energization of relay iEB receives'cu'r-rent but the slow-to-oper- I ate armature of relay 836 does not respond at o'nce, armature cf relay MI operates, motor 38 attains predetermined speed and tuned transrormer 1'53 -"supplies current to relay 69, relay 59 operates and energizes relay 36 over an obvir ous circuit but the slow-to-operate armature of rr'e'lay 96 does not respond at once, armatur'e of relay :35 operates and supplies current to relay ss, relay as operates, contacts litfland 1 6! are attracted, relay '55 is energized during the'stop signal period or'wh'en no' sign' al is be ing transmitted over basic circuit A, and supplies current through its left-hand armature and conductor 9 to slow-to-opera te relay I 45, the

armature of slow-'t'o-operate relay 96 operates,

and the armature of slow-to-"oper a'te relay 145 operates. The operation of those relays effects the following conditions to establish multiplex operation: v

Upon the operation .of relay 69, the direct connection between conductor 5-8 and regenerative repeater 43 is broken and a substitute path is formed through ieft-hai1d contact controlled -by cam 33 and through outer left-hand armature of relay 5%) to repeater E3. Receiver '12 at substation 73 is now connected to ex-tension conductor '5] for ibuta brief interval every unitary signal ii r-ipulse period since distributor shaft 32 as well as shaft 22 completes one revolution in each unitary signal impulse period. Cam 33 is provided with a "short recess so that only a small portiono'f a signal impulse is transmitted thereby. By properly orienting the cam followers, it is possible to pick out that portion of a signal' 'impulse which is least subject-to distortion and-transmit that portion to-a repeater, and

prevent transmitting wrong signals therefrom. Cam 33 closes its contacts to receiver 12 for :but a short period in every signal impulse period and permits thepolar relay of the regenerative-repeater at 43 to be conditioned by variable :polari-ty voltage supplied thereto from the armature of polar :re'lay 156' in accordance with the signal impulses being transmitted. The regenerative-repeater at 43 will regenerate "these shorter impulses into full length impulses-for propagation over conductor "H to receiving recorder 'lz at substation-13; The contacts of distributor cam 33 will come into operationin phase withsign'als generated initially at substation 11, because the contacts of cams zl and 3l'will have phased the distributor shafts 22 and '32. v

When slow-to-operate relay J36 operates, it energizes :relays 54 and and the connection at l! between conductor I and extension conductor it is m'terrupted and'a substitute path is formed from conductor 1 through inner righthand contacts "of operated relay 55 and contacts 152 con-trolledby cam '23 to extension conductor .3, thus includin distributor contacts I 52 of cam '23'inithe transmission pathof basi'c circuit A. The :conductor I now occupies -but one half of the time of extension conductor 3,-' the other half time being now available for the addit me circuit D through cam controlled cont-acts lat. :Thus the transmitting portion or the systerniis concli tione'd for synchronous multiplex Y telegraphy in Which transmission from basic circult-A and additive circuit B o'verextension conductori3 1s impulse cy {impulse with succeeding signal impulses origin'ating alternately in circuits A and B.

WhenJslow-to-operate reiayfat o erates'its "armature connects the transmission line bl through .to receiving. recorder M6 at: substation IM by means or tuned :ifelay 65, olar" relay aeg line right-hand contacts controlled by icam "33', inn'er ie'ft han'd armatureof irelay F69 armature of :relay at, and regenerative xrepeater or. I with additive circuit. B connected ;in this rmarme'r with its irecei'ver l 46, the :synchnonous :multiplex system is complete. Slow-11:0 -.o.perate .relay 2M5 w-hentoper at'ed-:enehiizes lamp? I134, indicating Fto the oper :ator ,atstati-onmu that toonductor -2 new? con- :ditioned forioperation. - Relays 95, 136 and .are constructed-or adjusted to such delay periods of operation as is required to. assure the closing of their contacts in the desired order.

V The operation of the additive circuit between substations I41 and I48 is identical withthe described operation of the basic circuit, the additive circuit utilizing regenerative repeater I49, storage repeater I50, alternative contacts in relays 55 and 69 and alternative contacts controlled by cams 23 and 33 respectively and sharing the line time with basic circuit A. v

1 As indicated previously, there is provided a means for changing the polarity oi" the power applied to relays 53 and 83 in order to vary the positions of their respective armatures. In the presentjembodiment, a contact I53 is actuated by a transmitting phasing cam 24 to apply potential over line to relays 53 and 83 and there is included in this circuitgthe camccntrolled contacts at regenerative repeaters I5 and I3 so that the circuit is operative only when it is completed at each repeater. Under the influence of cam 24, contact .I 53 vibrates between cor-operating contacts to apply alternately positive potential from line I29 and negative potential from line I38 to the relay circuit. In like manner, there is alternately applied positive and negative potentials respectively from lines I56 and I55 to contact I54, line 8,.

cam controlled contacts and relay windings ofregenerative repeaters I49and I50 associated with additive circuit B. It may be seen in Fig. 2 that there is included in the circuits to relays 53 and 83, armatures I60 and I6I to render the relay circuit to regenerative repeaters 53 and 83 inoperative until distributor 2I attains predetermined speed. I

As explained above, upon the reception of the start impulse at a regenerative repeater, such as I5, the circuit to'the polar relays 53 and 83 is interrupted at the cam controlled contacts at the repeater and remains interrupted until the reception of the stop impulse. Therefore, battery applied over line 5 through contact I53 is effective on the relays 53 and 83 only when the regenerative repeaters have finished repeating the signal-impulsesand received the stop impulse and, accordingly, there can be no mutilation of the signal combination which would result if the polarity of the relays 53 and 83 were changed during transmission of a code signal combination.

The operation of the transmitting phasing cam 24 and its contacts I53, I54 isas follows: .A cam in regenerative repeater I5 moves away from its follower and opens its electrical contact I5I upon receipt of the starting impulse of a permutation code signal, retaining the contact I5I open until receipt of the stopimpulse of the, code signal. Withdistributor cams. 23 and 24 in the angular positionsshown, cam contact I52 is closed connectingconductor I to relay 56 for transmission and contact l53'is closed to supply negative battery over line 5 to relays 53 and 83, positioning their armatures against their lower contacts and including storagerepeater I6 in the transmission circuit. Should a starting impulse begin at this instant at substation II, it would be delayed'one half impulse period by the regenerative repeater I5 and) the.repeated starting impulse would be emitted from repeater I5 when cam 23 had rotated one half .revolution, opened contacts I 52 and disconnected conductor I from relay 56; accordingly, the starting impulse must be delayed for a further half impulse period until contacts I52 may be reclosed by the cam 23. Since the starting 'im'pulse was received with armatures ofrelays 53'and 83 against their lower contacts, the stor-. age repeater I8 is included within the transmis sion circuit. Thus, the starting impulse emitted by repeater I5 is transmitted into storage repeater I6 instead of into conductor I, and at an instant one half impulse period later it is emitted from storage repeater I6 into conductor I, at which instant the contacts 152 are closed and conductor I is connected to relay 56 for transmission of the impulse into the carrier conductor 51.v V a A starting impulse initiated at substation II when contacts I52 are open will be delayed for one half signal impulse period in the repeater I5 and therefore, will be emitted from the repeater I5 when the contacts I52 have been closed. In such instance, cam 24 will be in a reverse position from that shown in the drawings at the reception of the starting impulse and the reverse polarity of current will be applied to the windings of the polar relays 53 and 83 positioning their armatures against their upper contacts. .This setting of relays 53 and 83 connects conductor 52 directly to conductor I through the upper contact and armature of relay 53, avoiding storage repeater I6. This condition prevails during the reception of the entire signal combination and, accordingly, a delay of one half unitary signal impulse is introduced into the transmission and the repeater I5 emits the regenerated signal impulses when cam 23 has revolved one half revolution and closed contacts I52, completing the transmission circuit from conductor I to polar relay 56.

When both the basic and additive circuits are associated over the synchronous multiplex system above outlined and one circuit is idle, such as basic circuit A, the polarity applied to its associated polar relays, 53 and 83, is reversed at every half revolution of the phasing cam 24 vibrating the relay armatures and connecting the main channel and branch circuit to first one and then the other of the repeaters associated with the particular branch circuit. Upon receipt of a starting impulse from substation II, the cam controlled contact I5I opens the circuit of the windings of relays 53 and 83 and the condition of the relays as determined then is maintained throughout the transmission of the ensuing code signal. The determined condition of relays 53 and 83 inserts a proper delay in the transmission circuit, synchronizing the transmission from the regenerative repeaters with the operation of distributor cam 23. It is understood that each circuit, basic or additive, is equipped with a delay mechanism such as that already described for conductor I and each operates in precisely the same manner to maintain proper phase relation between the transmitters and the cam controlled contacts which apportion the line time.

The transmitters in the branch circuits are adjusted to operate at a speed less than the transmission speed of the multiplex. When the branch transmitters are operating at their maximum rate, there will be a gradual shift of phase between the signals generated and the multiplex distributor, cams. Accordingly, when multiplex operation has been established and the transe mitter in a given branch circuit is operating at its maximum rate, transmission will be through one setting of the regenerative repeaters of that branch for a certain number of complete signal combinations. After the multiplex distributor has crept sufficiently to shift the phase relation of the distributor cams and the signals in that branch circuit, the transmission phasing cam will transfer the branch circuit, to the alternate set:-

ting of the regenerativerepeat'ers from which transmission will be carried on until the distributor again causes a sufficient hase shift to return transmission to the first setting of the repeater mechanism- The number of signals transmitted from one setting of the repeaters will depend on the speed difierential between the branch transmitter and the multiplex distributor. If transmission is from a keyboard, the rate at which the shift takes place will be quite variable.- At the beginning of each signal combination, that branch circuit condition is selected which supplies the best phase relation and this condition is maintained for at least the entire signal combination. When the next signal combination is received, whether immediately or some time afterwards, that condition of the branch circuit is selected which afiords the best phase relation.

To remove the additive circuit from operation and restore the aforedescribed normal condition, manual key I53 is operated momentarily breaking the holding circuit and de-energizing relays H 2 and H3. Relay I12 releases immediately and at its outer right-hand contacts completes a circuit to supply uninterrupted 1800 cycle current to carrier conductor 51 to operate tuned relay I22 while at its inner right-hand contacts, relay H2 breaks the circuit to slow-to-operate relay 133. By attracting its armature, relay I22 places and holds the armature of relay 123 against its upper contacts placing acontinuous direct. current in the circuit of tuned transformer I46 thereby releasing relay MI. At the same time, relay I23" interrupts the circuit to slow-torelease relay I25. With relay I4I de-energized, the circuit for relay $9 is open and the extension circuit Bl is, accordingly, connected directly to receiver I2 since the circuits of the contacts of cam 33 are open at the armaturescf relay 69 and receiver I45 is thereby taken out of the circuit, Relay I35 then releases its armature breaking the circuit of relay d causing it to release its armatures and de-energize relay 55. Relay 55 at its outer left-hand armature opens line conductor 9, de-energizes relay I 45 and extinguishes line lamp I34 to indicate at substation I48 that its circuit is now inoperative. At its inner righthand contacts relay 55 connectsbasic circuit A directly to extension conductor 3 re-establishingthe normal simplex circuit and disconnects conductor I from contacts I52. Contact I1 is a make-before-break contact, and conductor I is connected to extension conductor 3 by contact Il before being released at the inner right-hand armature of relay 55 thus retaining. communication continuously over basic circuit A. At its outer right-hand contacts relay 55 disconnects additive circuit B from extension conductor 3. Relay E i-disconnects at contacts IE8 and ISI the transmitting phasing cam 24.

Slow-to-release relays H3 and I25 then operate-and stop motors 28 and 38.

The positions of the armatures of the polar relays at the regenerative repeaters at the time contacts I50 and I6! are opened determine whetherthe storage repeater I6 will be included in the transmission circuit when the system is again conditioned for normal operation. In Fig. 1 storage repeater I6 is included. in the transmission circuit.

To keep the circuit drawings. clear, there have been illustrated at central station as only one pair of branch circuits A' and B, and its associ ated relay circuits, distributor controlled contacts;,and;;transmission phasing-camz-ior'properly allocating the line time of extension conductor (3' between the branch circuits. At IIlI, Hi3 and )5 there are indicated other extension conductors connected to the carrier conductor 51 and as many such, extension conductors may be provided as desired. It is to be understood that there will be associated with each such extension conductor a pair of branch circuits, relay circuits, distributor controlled contacts, and a transmission phasing cam in exactly the same manner as clescribedin detail for extension conductor C. In operation each extension conductor of the" system will modulate an alternating current of a distinctive frequency in a manner well known in carrier systems. 7

At central station 3% there are shown a tuned relay 9i], actuated by signals received over carrier conductor a polar relay 83, distributor co'nrolled contacts represented at 94, and relay (fir-- .cuits and repeaters indicated at 95 to associate substations 95-3 and I08 with tuned relay At I532 and IM are represented additional extension conductors at central station 36 with which similar means is provided to complete cornmuni cation thereover in a manner contemplated by this invention.

Although a carrier system has been disclosed, the invention is by no means limited thereto and the extension conductors of central oflices 2S and 333 may be directly connected, affording a plurality of individual communication circuits each of which would function normally as a simplex circuit and in an alternative condition, function as a synchronous multiplex circuit. To enable such a system to operate under the alternate condition, it is necessary to connect line conductor 2i directly to tuned relay I22 so as to provide a synchronizing channel. With such a circuit arrangement depressing manual key III would start motor 28 at central ofiice 2i] and motor 38 at central ofiice 36 in synchronism and phase to simultaneously establish multiplex operation over a plurality of distinct circuits and the synchronizing channel would assure the proper phasing of the substation apparatus and the distributor cams in the same manner as that described for the system disclosed in Figs. 1 and 2. Direct current signals may then, of course, be used in place of a modulated carrier current.

Individual channel orientation IE5 of the bell crank I62 is pressed by a com pression spring IE6 which engages afixed frame member it] and is urged against an adjustment screw' I68 threaded through a member Idilfixed to the frame. As the bell crankmember is rdtated by its adiustment screw, the follower is advanced or retarded with reference" to the rotating cam, thus operating itsassociated contacts earlier or lateras desired. There may be ro= vided an adjusting means fore'ach follower of the pair of followers associated with the distributor cams. This feature facilitates adjusting the systern and assures synchronous operation;

If desired, asingleniea ns' may be provided to adjust'both cam followerssimultaneously; Su'ch an arrangement is illustrated in Fig. 6"- wherim the adjusting means is illustrated in connection with a multi-lobe cam whose utility is to be pointed out subsequently. Of course, this adjusting device may readily be employed with the cam demonstrated in Fig. 5.

In Fig. 6, rocker member III is pivoted to the frame at "2 and carries cam follower I'I3 as well as cam follower I64. Both cam followers, I64 and I13 pertain to the same extension conductor and are thus adjustable by one rocker memher and thumb screw. The members in Fig. 6 which are similar to members in Fig. 5 bear similar numerals primed.

Multiple-lobed cams The distributors shown in Fig. 2 are illustrated with cams of a single lobe, and shafts 22 and 32 are presumed to rotate at a speed of one revolution per signal impulse line time period. It is possible to increase the number of lobes on each cam and proportionately decrease the rotational speed of the shafts 22 and 32. In Fig. 6 seven lobes I14 are shown on cam 33 corresponding to cam 33, and shaft 32, corresponding to shaft 32, is presumed to rotate at a speed of one revolution per 7-unit code signal time period.

First modification Figs. 2 and 3 when combined present complete circuits illustrating a modification of the system of Fig. 1 (employing a mechanical means instead of an electrical means for conditioning the delay mechanism). Structural elements in Fig. 3 which have analogous elements in Fig. l are provided with numerals having similar tens and units digits and detailed descriptions of such elements are not repeated here.

In Fig. 3, mechanical relays 32I and 322 are provided for operating contacts equivalent to the contacts operated by polar relays in Fig. 1, to place storage repeater 3I6 either in or out of the transmission line. In the mechanical relay 32I, a motor driven shaft 323 acts through friction disc 324 of a friction clutch not otherwise shown to drive two integrally united wheels, namely, ratchet Wheel 325 and cam wheel 326, which are restrained either by armature 321 or alternatively by armature 328. A cam follower 33I rests on a lobe of cam 326 and holds contacts 332 and 333 in operated condition (as shown in relay 32I) when ratchet 325 is restrained by armature 321, or permits the contacts 332 to assume unoperated contactual relations with respect to contacts 333 when ratchet 325 is restrained alternatively by armature 328 and cam follower 33I rests in a depression of cam 326 (as shown in relay 322).

Magnets 335 and 336 control armatures 321 and 328, respectively, and are energized alternatively by current over conductors 329--I29, right-hand winding of relay 55, contact I60 to contacts I53, or conductors 333-I30, center winding of relay 55, contact I6I to contacts I53 of cam 24, and conductor 5-3Il5 through cam controlled contacts 3I9 and 35I to ground.

With the circuits of Fig. 3 coupled to those of Fig. 2 there is illustrated a communication sysconductor 392 ofthe additive circuit to extension conductor 3 because, until that condition is established, the mechanical relays are held in one position since the, circuits to magnets 335 and 336 are open at contacts I60 and I6 I.

When shaft 22, Fig, 2, is operating at synchronous speed and neither regenerative repeater 3I5 nor 3I6 is repeating a signal combination, contacts I53 .of cam 24, will supply current from negative battery, Fig. 3, alternately through magnets 335 and'336. The circuits are: ground, cam contacts 35I and 3I9, line 305-5, contacts I53 at cam 24 then to either line I29, contacts I60, right-hand winding of relay 55 to line 329, magnet 335 and battery or to line I30, contacts I6l, center winding of relay 55, line 330, magnet 336 and battery. When cam 24 is in the angular position illustrated in Fig. 2, magnet 336 is energized, ratchet 325 is restrained by armature 321, follower 33I is resting on a lobe of cam 326, contacts 332 and 333 are closed, and the magnet of storage repeater 3I6 is energized by current flowing from positive battery, through magnet of storage repeater 3I6, operated contacts 333 and 332, conductor 352, contacts of regenerative repeater 3I5, and battery. If the start impulse of a signal combination were received by regenerative repeater 3| 5 at such an instant, the repeater would start and would open the cam controlled contacts 35I,-breakin-g the circuits to both mag-,

nets 335 and 336, thus retaining the cam 326, follower 33I and contacts 332-333 in the conditions illustrated, and resulting in the operation of storage repeater 3I6 in response to the operation of regenerative repeater 3I5. The contacts of storage repeater 3I6 then would operate to transmit signals over conductor 30II to relay 56 and to the carrier conductor 51. In this condition with repeaters 3I5 and 3I6 in the transmission circuit, a'delay of a full signal impulse period is introduced in the transmission, as was true of the corresponding condition of the appa-' ratus of Fig. 1. contacts at each regenerative repeater, this congral number of complete signal combinations.

When cam 24 is in its alternative angular position, with its controlled contacts I53 in reversed contactual relations, magnet 335 is in energized condition, ratchet 325 is restrained by armature 328, follower 33I is in its lowered position, contacts 332-433 are open, and the magnet of storage repeater 3I6 is energized by current flowing from positive battery, through the magnet of storage repeater 3I6 and unoperated contacts 332 to negative battery independently of the contacts of regenerative repeater 3I5. If the start impulse of a signal combination were received by regenerative repeater 3I5 at such an instant, the repeater would operate and would open the contacts controlled by cam 35I, breaking the circuits to magnets 335 and 336 and thus retaining the follower 33I and contacts332333 in unoperated condition and resulting in the operation of regenerative repeater 3| 5 to transmit signals directly over conductor 352 and conductor 30I-I to relay 56 without time delay in'storage re-- Because of the cam controlled the repeaters 315 and 3H; and condition of the transmission circuit is maintained by the cam controlled contacts 3| 9 and 35| for an integral number of complete signal combinations. Since those contacts are not closed until the reception of the stop impulse, there can be no mutilation of the signal combinations.

Signal impulses delivered to conductor 3lll--l by repeater 3l5 or alternatively by repeater 3l6 will be in a permissible phase relation to the' op eration of distributor'cam 23 for the reasons set forth above in connection with description of op? eration of the structure illustrated in Fig. 1.

Mechanical relay 322 is similarlyoperated Lin-Q der the control of the cam contacts, of repeaters" 349 and 350, conductor 3066, contacts 54 of" cam 24 and return conductors [55 355, ,|56*' 356, to the magnets of the mechanical'rela'y 322;

thereby controlling the-switching of the storage repeater 350 in-to and out of the transmission path froni' Substation 34% to conductor 30-2 2 a'n-d to relay 56: At 345 is'the line relay opera tive 1 to illuminate' lamp- 334 when the alternate condition has been established and transmission aybe carried on from'substation348. I .l b md fic ln- -this second modification, the regenerative repeater and the storage repeater, illustrated as separate structures heretofore, are combined-into one unitary mechanical structure. Y Illustrated in Figs; 4 and 7 to 12, inclusive, is a--mechanical' regenerative repeater of the form shown and described in United States Patent No.- 2,105,173, issued to W."J. Zenne'ret a1.,-the=-structur 0f the Zenner et a]. patent being modified for} the purpose s' of the present Jirivntion to generate two. signal impulses at the repeater-in response to eachreceived signal impulse, the two regenerated signal impulses being similar inna ture but displaced in time from one another. Accordingly,'the disclosure of the noted- Zenner et-al, patent is made a part of this application and will be referred to further herein; 1

Referringto-Figs.7 to 12, inclusive, there is shown mounted rigidly'on'a frame plate 410 a pivot s'tud'4ll upon which there oscillate indepe'ridntly'an armature member-4H! and first and second repeating members425 and 435, respec threw. I l TI. --'Ihe'repeater magnet M3 is provided witlr'an armature 412' cf yoke form'an'd pivotally'mount= edon stud 4H by'yoke arrris4l4 and"4l5' (see Fig. 9). The armature'comprises a 'plurality'of extensions, namely, portion 4'I6which "is attracted directly by the magnet, a first cam follower 4|! and'a-second cam follower 4l8 passing through an opening 423 (see Fig. 10) in frame plate 4'lfl' and these followers are controlled bycams 435 and 486, respectively, for mechanical ly assisting armature 4'l2,'a starter striker 419 on anarrn 433 to initiate the operation 'o'f' -th'e repeating mechanism, 'a latch lever420 which is s-subextensien on camfoll'ower 4| 8 andwhich determines the delay inserted in the transmissioncir'cuitQand a pair of anchor arms 424 and 422 to which springs extend'and provide a'self' centering" mechanism for repeatertongue 425 with respect to the armature 4l2,

''-The regenerative repeater-member 425 also pivotally supported by the stud member 4 ",engages th'e'stud member by yokearfiis'424positioned be:

twenthe yoke arms 4l4 and "M5. lit is provided with a plurality treperatn g extensions;

namely; a pair of signalrepeatingelectrical contacts 426 to transmit the regenerated signal impulses, a pair of transfer abutments 429, and 430 on a lateral arm 421 passing through an opening 428 in frame plate 4!!! to control regen- 5 "erative repeater member 435, a lock edge 43! and a jockey edge 432 to hold repeater member 425 in its variouspositions ,(seeFigs. 8, 10, and 12).

A storage repeater member 435 also is pivotally supported by the stud member 4| I, engaging 10" thestud4ll by yoke arms 436 and 431 on alter-, hate sides of plate 4l0-andconne'cted through the web body of the member 435, passing through an opening in the frame plate 4W In front of the frame 4lll, the web body of themember 435 it carries an'integralextension 438 provided with apairofelectrical-contacts 439 which engage one or the other pair of two pairs of anvil contact repeater member 435-to ,causeiit" to regenerate poi-nts"44'0" (seeFigi 7). At the back of the framearm '4 extending from the yoke arm 43'! andand r peapjsigharimpulsesanaat comprises 'a transfer levr--(see-'Fig"sl 7,8, *9, and 12) 442 pivoted on a fixed post 443 and provided with a-am follower 4'44 a'i ndfiivitli an extension arm 445 r'ies at its distal jen'd a pivot-pin 446. t "pin m earnes a transfer 7 T 441 which upon being movd by the am" 445 pnder'; power from cam follower 444 may engage alternatively either the abutment mp5 the abutment 430 on extension arm 421 of repeater member 425 and 5' 'be rotated upon its supportirig pin-446. "Thep'articular abutmehtwith which- T 44'! eng ges-1's determined by the position of repeater mernbr' 425'." That isiif repeater' member 425 "is infits lower position repeating a spacing impulse, abutment 429 on extension 421 o'f'member 425 is in'ali'g'nrnent with and Willbe engaged'by'T 4 4,1, whereas, when a marking impulse--is"being repeat'ed by member 425, that' me'rnber is in its'upperfiositionandiT 441 will engage hlltiflerlt' 43c it; (see Fig.8)", Transfer T 441 carries a transfer pinf4'48-which at "all times --i's"con'fined within; the bifurcation of the arm 44l of storage mam-- beij 435 and which acts to shift the member 435 oscillating upon its supporting "stud 4| I in re- 3 so spons'e t the shifting or T 441 about its' pivot- 44s.-- I

Acontinuously driven power shaft 450 is provided as shown in the zenner 'et al. patent referred to above. This shaft carries a first cam .is sleeve 45l and asecond carn'sleeve 452 (see 11).-' The need for a'plurality of'cam sleeves ation of th'e'regenerative appa'ratus. Friction plates 453'a11d454 are fix ed 'to "Sh rman while ishoul'dered friction plates'i455 and 456 are slid ably carried by sh'aft' 450; the shouldersof the 3 platesbein'g splined to'ge'tlief'and the assemthe "described cam sleeves; I sion spring 46! keeps all friction' m'embers"under Pre sure. 1 I

A single compresmechanism lprovided as 'sl'iown in the Zenner ct.

al.ffaatent but' not reprodu'ced here andiis' released by an'rna t rewls and-startin striker 419. Cam sleeve- 4-52 'is+held"latched b'y a latch arm 3'5. 470 when the arm is in engagement-with a:tooth on cam 461 (see Figs. 8, 9, and 11). A'rocker shaft 468, journaled in the frame plate 410, carries fixed upon it at one end the cam follwer 469 which follows the cam 466 on the first cam sleeve 451 in front of the frame plate 416, and carries fixed upon it at the other end the latch arm 410 which engages the cam 461 on the second cam sleeve 452 at the back of the frame plate 410.

A latch lever 419 for repeater 425 has the form of an extension arm on alatch lever member 481 of yoke form extending on either side of plate 410, the two yoke arms of which are pivotally supported at the two ends of a stud member 4811 fixed in the frame member 416. An extension arm 416 of lever 481 terminates in a cam follower for the release cam 415 on the first cam sleeve 451 and is operated by the cam 41513 operate the lock lever 419 in the manner illustratedand described in the patent to Zenner et al. A further extension arm 418 at the opposite end of lever 481 terminates in a cam follower for the release cam 411 onthe second cam sleeve 452 (see Figs. 7, 9, and 12). A spring 449 urges lever 481 counterclockwise, retaining its follower projections against these cams.

Springs 482 and 483 approximately alike in all dimensions, extend respectively from anchor arms 421 and 422 on the armature member 412 to regenerative repeater member 425, providing a self centering articulation. A jockey 491 pivoted at 498 is retained by spring 499 against the described jockey edge 432 on the repeater member 425 (see Figs. 7 and 9).

Cam sleeve-452 carries a cam 484 for thedescribed cam follower 444 of the transfer assembly 442. Cam sleeve 451 carries a cam 485 for follower 411 and cam sleeve 452 carries a cam 486 forfollower 418, both followers 411 and 418 being integral with armature member 412 as described above. p

Means is also provided for maintaining the delay inserted in the transmission system at a given value for the duration of the transmission of anjintegral number of complete signal combinations. Cam sleeve 452 carries a cam 481 (see-.Figs.,8'and 9) for a cam follower 489 integral withv a lever 488 of yoke form pivotally supported upon a fixed stud 496 carried by plate 416 one arm of the yoke passing through an opening. 496 (see Fig. '7) in the frame plate 410 and, being provided withthe said integral cam follower 489 and with a notched locking extension 492. A rocking latch 493 pivoted upon a fixed pivot 494 may engagethe notch in the extension 492 as illustrated in Figs. 8 and 12 and may be rocked out of latching position by the operation of the described striker 420 (see Figs. 9 and 12) on armature member 412 upon" the receipt of the starting impulse.

Reference to Fig. 13, wherein there is illustrated a, timing chart for one particular embodimentof the combined repeater mechanism, will demonstrate the necessity for a plurality of cam sleeves and render the subsequent description of the operation of the apparatus more easily understandable.

In Fig. 13, A represents a start-stop code signal received by magnet 413,1 the startimpulse of which releases'first cam sleeve 451;

B represents the operation of cam 436 and shows at b' the release of second cam sleeve 452 one half a signal impulse period after the release of first cam sleeve 451;

C represents the actuation of release cam 415 permitting the positionment of repeater member 425 to correspond to the position already assumed by armature 412 and at 0 there is indicated the release of repeater member 425 one half an impulse period after the reception of the start impulse, interposing a delay of one half a signal impulse period between the received.

signal combination and the signal repeated by the first regenerative repeater unit;

D represents the cycle of transfer cam 484 and demonstrates at d the transfer of the first, or start, impulse through the transfer mechanism to the second, or storage, regenerative repeater member 435 at a full impulse period after the received start impulse; that is, when the No. 1 signal impulse reaches the repeater magnet, the start impulse is being transferred to the second regenerative repeater 435;

E illustrates the operation of cam .485 to assist the operation of the armature 412 and 6 indicates the operation of follower 411 by this cam so that the armature is under the control of the No. 1 received impulse;

F discloses the operation of release cam 411 which is similar to that of release cam 415 in G is a diagram of the cycle of cam 466 for providing assisted armature operation and the cam is actuated in a manner similar to that of cam E except that cam 486 is for those impulses exclusive of the first impulse;

H and I'represent'the signals repeated by regenerative repeaters 425 and 435, respectively, andshow the delay of one half a signal impulse period in signals; transmitted by repeater 425 and "a delay of a full signal impulse period in the signals transmitted by repeater 35;

J represents the operation of cam 481 to return the control to magnet 595 when storage repeater 435 is transmitting the stop impulse.

Astudy and comparison of curves A, B and D will revealthat the transfer of the stop impulse from the transfer mechanism to repeater 435 takes place at (11 at which time the original stop impulse has been fully received by magnet 413 and first cam sleeve 451 is at rest. Hence, if transfer cam 484 were carried by first cam sleeve 451, the stop impulse would not be transferred to repeater 435 and for that reason a second cam sleeve 452 is provided to accommodate the transfer cam 484.

At g5 is indicated one time at which the armature 412 is mechanically translated to its attracted position to afford assisted armature action and it is there clearly illustrated that this is very near the time at which first cam sleeve 451 is arrested, having completed one cycle. Similarly, at 16 there is represented the time at which repeater member 425 is released to be positioned'to transmit the stop impulse and this, too, occurs at nearly the time when the first cam sleeve 451 is arrested. Although it is possible to arrange cams 485 and 415 to perform all the armature assisting and releasing operations respectively, the present embodiment of the invention contemplates dividing these operations, as disclosed, between cams 485, 486 and cams 415, 411. Since the second cam sleeve 452 is necessary as above shown, the additional cams 486 and 411 are also mounted thereon to permit more facile orientation and assure the required time relationships. The particular alassess;

mean-en br ep'eiaadfis eetweefi cat's 4855488 an cam lia, m is" not im ortant-, and, 'ifdesire'd; cam 'ase maybe t me tooth cam,as"-inay ;cain 411. 'Th'e cams-B and 411 are provided inorder to provide for more certain time' 'rlationships-at the ftimes' indicatedatg5and f6','respectivelyn 1 In the ffirst two modifications of this invention there was illustrated a earnswitch at each regen erative repeater, provided to assure that the de lay-inserted in the transmission'circuit bemaiiri tained during the transmission of anfintegiral number of complete signal combination sto pre; vent signal mutilation. Means 'i's 'providediinthe present modification to "give the sam assurance and it comprises contacts 50!} 5 l 12, and 503 controlled by armature 584'of magnet 585 (see Eigs. 4, 17, and 12). In the condition show'n inLFigQffl armature 504 "has connected communication line 40 I to storage repeater 435 introducing a delayofv a full signal'impulse in the transmission circuit. With armature 504 'a ttra6td;line' 40] is eon t';-' ed ts igefiemweteeeatr 425' with 'a' delay of halfa signal impulse in the circuit, The locking edge49 l of member'488 operates under the .con trel-of esraaanb' maintainarmature 5114 in the. condition existent upon the receiptfof the start impulse foij the transmission of one entire signal combination. curve 'J demonstrates that the locking edge 49! is-noteperated to release armatur e 504 untilafter the'transfer of the stop imguis to' repeater 435,. at which time first cam sieeveasl has beeniarrested and, therefore, secondcam sleev 452 is necessaryto providea res. leasefor armature 5 94 after a'signal combination lie-speed fully repeated by repeater 435 as well as re'peater1425.

circuits ffor'connecting the combination re; pe'ater into the system .are illustrated in 'Fig. 4, which when joined to Fig. 2 shows complete circuitsfor the second modificationof the invention. Substationf5ll andloo mbination repeater 5I2 are connected overcpnductors 'flj and 405 to lines 1 and 5 of 'a'ba sic circuit of 1 16 .s stemgwhile' substa 'on 5l3 and combination repeater 5I4 are connected over" conductorsi402 and 4tl6 to lines 2' and (inf the companion additive circuit of the s stem. 7

'rhis system; as was ass of the. peasant;

tacts 5l'1; conductor-"529, right-hand winding of relay 55, anna'ture' mo, iine rzs'; contacts 'l 53at cam; 24, line 5, amesaasana *ground'is' open at armature-160. Magnet 508 is held energized by current in a circuit including conductors 488-18, contacts I54 and conductor" |58-'556. "f

Upon generation of a" permutation code signal at substation 5| I, magnet 4 I3 is. de-enrgized at the beginning of the start impulsel' Armature 415 (see Fig.7) is released and striker 419 (see Fig, 9)- releasesthe first'cam sleeve '45l as described in the Zenneret'al. patent Releaseof armaturey4l6 also" operates armature member 2 clockwise under the force of =spi in'g434and' striker, 420- which "engages and racks the g' latch 493-;to release the locking member 488 which,

urged by-l he ten'sion of space 49 5, -p ags t e armature 504, preventing the shifting of thecontact-spring 50f during the periodof transmission of .the then ensuing code signal. Because of the movement of armature member 4l 2, on of the springs 483 now tensions the repeater member 425 against the latch4l9.

After a delay of one half signal impulse time period, cam 415 operates the follower 416 and latch 419 as described in the Zenner et al. patent and the cam 485 operates the follower 489 to rock shaft 468 and latch 478 thus releasing the second cam sleeve 452 with a delay of one half signal impulse time period after the release of the first cam sleeve 45!. Latch 4T9 momentarily releases the repeater member 425 which shifts its abutments 429, 438 and also operates its electrical contacts 426 thus repeating the starting signal impulse into the contacts 426 with a time delay of one half signal impulse period as compared with the original signal impulse. I I I After a further delay of approximately one half signal impulse time period from the instant of operation of the contacts 426, and just preceding the beginning of theNo. 1 character code impulse of the permutationcodesignah presumed to be an impulse of marking signal nature, cam 484 operates its follower 444 whichpropels the T 441 against the shifted abutment 429 and by the resultant rocking of the T 44! effects a shifting of arm MI and storage member 435 to repeat the starting signal impulse into the .contacts 429 with a time delay of one full signal impulse period as compared with the original signal impulse.

' The first impulse is then received, energizing magnet 4| 3 but with the holding type magnet employed, the magnet is not strong enough to attractits armature. After the No. 1 impulse has been sustained for nearly half a signal impulse period, cam 485 operates its follower 4|! to restore, armature member 4 l 2 to. its attracted position as described in the Zenner et al. patent,

thus causing spring 482 to tension repeater member 425 for a marking signal impulse. Since a marking impulse is being received, magnet 4| 3 now retains armature M2 in its attracted position, The employment of a holding magnet of this nature enables the multiplex to be conditioned by only a part of the received signals and consequently, limited mutilation of the received signals is eliminated and not transferred into the multiplex system,

At an instant one half signal. impulse time period after the beginning of the No. 1 impulse in magnet 4&3, cam 47'! operates its follower 418 and latch 419 to momentarily release the repeater member 425 which is then shifted by spring 482 to repeat the marking impulse into contacts 426 and to shift abutments 429 and 430. At an instant approximately one full signal-impulse time period after the beginning of the No. '1 impulse in magnet 4|3, cam 484 operates its follower 444 and propels the transfer T 441 against restored abutment 430 to operate the storage repeater member 435 and to repeat theNo. 1 signal impulse'into the contacts 439 with a delay of one full signal impulse time period after the beginning of theN'o. 1 signal impulse in magnet 413. In like manner the remaining impulses oiv the signal combination are repeated at contacts 426 and 439.

is stopped by stop am 414 as described in the try-engagement of cam, tooth- 461 with latch arm 410. Just before the second cam sleeve 452 stops, cam 481 engages its follower 489 and shifts the locking member 488 into position to release the armature 504 in which position the locking member 488 is engaged by locking latch 493 and is restrained pending receipt of a starting impulse by the magnet 4|3. All apparatus is again at rest.

During the receipt and retransmission of each successive code signal, the signal impulses are repeated into contacts 425 with a delay of one half impulse period and also are repeated into contacts 439 with a delay of one full impulse period. The position of contact spring 50| determines whether the basic circuit 40| shall be connected to contacts 426 for retransmission with a delay of one half impulse period or to contacts 439 for retransmission with a delay of one full impulse period. The position of contact spring 50I is determined by the position of armature 504 at the instant that the locking member 488 is unlatched by the armature 4|8 acting through striker 420 and latch 493 in response to a received starting impulse of a code signal combination.

In the normal condition of the particular embodiment of the invention under consideration, magnet 505 is de-energized, as illustrated in Fig.

4 and accordingly, line 40I is connected to storage repeater 435 and there is a full signal impulse period delay inserted in the circuit.

The alternate condition of the system, wherein the basic and additive circuits are operative, will now be considered and it will be assumed that the system is conditioned for synchronous multiplex telegraphy.

When additive circuits are being used, the distributors 2| and 3| rotate continuously and magnets 505, 506 receive impulses of current in uninterrupted sequence from contacts I53, I54 of cam 24.

The signal impulses for the basic circuit are transmitted through contacts I 52 (see Fig. 2), Should the beginning of the start impulse in magnet 4|3 occur with distributors 2| and 3| operating and with the distributor cam 24 transiently in the position shown with contacts I52 closed, conductor I29 would be open at contact I53 of cam 24, magnet 505 would be de-energized and contact I52 will be found open and the starting impulse will be transmitted into contacts I26 ineffectively. At a further half impulse period later the contact I52 will be found closed and the starting impulse will be transmitted into contacts I39, thence through contacts 503, 50I, conductor 40 I|, contacts of operated relay 55, contact I52 and extension conductor 3 to line transmitting relay 56. Upon the receipt of the start impulse, locking lever 488 operates and holds armature 504 immobile during the ensuing signal combination.

Should the beginning of the start impulse in magnet 4|3 occur with distributors 2| and 3| operating and with the distributor cam 23 transiently in its position alternative to that shown,

with contacts I52 open, conductor I29 would be closed at contact I53, magnet 505 would be energized and contact 50I would be in engagement with contact 502 connecting line conductor 40I to the regenerative repeater 425. At a half im-' tween successive code signals even though the larly operated contacts I52.

As a matter of convenience, extension con ductor 3 has been referred to in the appended claims as a main channel audit is this channel which is conditioned foreither simple or Sy Zenner et al. patent and one half signal impulseperiod later the second cam sleeve 452 is stopped pulse period later, the contact I52 will be found closed and the starting impulsewill be transmitted into contacts 426 thence through contacts 502, I, conductor 40|I, contacts of operated relay 55, contact I52 and extension conductor 3 to line transmitting relay 56. Signal impulses will be repeated into contacts 439 but without efiect since they are disconnected from theline.

The operation of combination repeater 5| 4 is identical with operation of repeater 5|2, transmission being over conductor 402-2 of the additive circuit and contacts I51 of cam 23 to relay 56. The operation of cam 23 in allotting the line,

time to basic circuit A and additive circuit B is precisely the same as that described above in connection with Figs. 1 and 2.

At the end of each revolution of second cam sleeve 452 the cam 481 engages its follower 489 and operates the locking member 488, withdrawing the locking edge 49| from engagement with armature 504, permitting the armature 504 to respond to magnet 505 according to the energized or unenergized condition of themagnet 505. The contact spring 50I thu may be readjusted invariably by the transmitting phasing cam 24 besuccessive code signalsare continuous as would be the condition with-a tape controlled transmitter operating at station 5| I.

Locking lever 488 carries two contact operating devices, shown diagrammatically in Fig. 4, for

operating contacts SH and 5|8 to prevent signal mutilation by converting to multiplex operation during the transmission of a signal combination over the basic circuit. That is, upon the receipt of a start impulse by magnet 4I3, latch 493 is rocked and lever 488 rotates counterclockwise under the influence of spring 495 disengaging contacts 5|1 and 5I8. .Should key I be depressed at this time, the establishment of multiplex operation would be delayed because the circuits to the energizing windings of relay 55 are disabled at contacts 5H and 5| 8. Upon the receipt of the stop impulse, member 488 is rotated clockwise by cam 481 and closes contacts 5|1.

and 5|8 permitting relay 55 to be energized over the circuit including battery, magnet 505, contacts 5 1, line 529 and right-hand winding of relay 55 or the circuit including battery, contacts 5I8,.

line 530 and center winding of relay 55. From relay 55, each circuit is completed through contact I53, line 5-405 and ground. Accordingly, conditioning the system for the multiplex operation may be accomplished without interrupting transmission over the basic circuit.

When the system is conditioned for multiplexoperation and one of the branches, say line 40 is idle, the transmitting phasing cam 24 through contact I53, line I29 and 529 alternately energizes and de-energizes magnet 505, vibrating armature 504 and connecting line40| alternately to repeater contacts 428 and 439 in phase relation with the operation of contacts'l 52. Consequently, when the multiplex condition is once established, it is maintained and no matter when transmis--' sion is resumed on line 40I, it will be properly phased with respect to the operation chronous multiplex operation. Similarly, conof regu- T ductor l operates as a start-stop simplex channel atall times.

Three modifications of the invention have been illustrated. Many modifications c'onformingto limitations and rearrangements .may be .-;con-

-structed without departing from the spirit ofthe inventionand the scope of the appended claims. What isclaimed isz' r 1. In a multiplex telegraph systemf a cominunication channel, a plurality of permutation code impulse transmitters, a mechanical distributor including a pair of contacts individuaLto .each transmitter and throughv which all codeicombinations of impulses from the .respective'tr ansmitters are transmitted, relay: meansz' for asso- 1 5- ciating each transmitter with'itspairlo'f contacts, and cam means constitutinga'"pairtof'said distributor for operatin said pairs-otcontacts to connect each transmitter cyclically to said'communication channel for multiplex operationand maintain said contactsclosedfor-the period-required to transmit .a complete code combination ofimpulsesr I I 7 2.;In. av multiplex tel'egraphsystem, a telegraph circuit, a transmitterassociated with said circuit, a contact operated at-regularly recurring intervals. to complete and -maintain said tele, graph circuit for the period of a code signal, a contact controlled by signals from said transmitter. andoperated atrandom inte-rvals to generate code. signals corresponding to thoseproduced under the .controLof -said'transmitten-and means j controlled by said code signals to transmit through said contact operated at regularly recurring intervals all of thesuccessionofimpulses composin'glsaid code signals as deterinined by said transmitter. 1

3. Inlatelegraph. systems-main channel; a branch circuit, meansconnecte'd to i said branch circuit to transmitat random intervals signals composed of a.plurality of unit impulses-, means controlled, by said signals to, transmit over-said main channel uniformly ,timed signals. corresponding to said random signals,l..andmeans for maintaining the maximum lagbetween said Erandom signals and said uniformlylitimedesignails Lto approximatelyoneimit impu1sc.;:.' l

-In a telegraph; system, ::a' main. channel, a

branch 1 circuit, Y means in said: branch circuit to v transmit signals,. first. means inrsaidi branch icirsuit. to repeat said transmittedlisignals, means to time the transmission of. signals from said branch circuit to said main .channel,.means to connect said first repeater. means directly tonsaid main channel when said timing means bears aproper phase relation to said transmittedsignals, asecand means .insaid branch circuit tolrep'eatsaid transmitted signals, meansto connect i'saidifirst repeater means. to. said second repeater u-n'ieans when said timing means bears .an'impropr pha'se relation to said transmitted signals, and means to connect .said second repeatermeans tox said main channel. .T5..In a.telegraph circuit, .aymairichannel, a

branch circuit extending .from .s'aid mainch'anneLLsyn'chronous telegraph apparatus operable oversaid main channel; start-stop-telegrapldapparatusgincluding. a? transmitter operable over said -.branch circuit, means operable rover. :said branch. circuit to generate a first setbf s'ig'nals corresponding .to the signalsemittedt -b'yfsaiid transmittenx: .means operable 1 :Iover" said ;;bra nch circuit to rgenerat'ela second:setmfzsigrialsgidem,

tic'al witli saidilfirstfset but lagging said first set by a predetermined amount, and meansto apply one or the other of saidsets of generated signals to said main channel in accordance with the phase relation of said start-stop apparatus and said synchronous apparatus.

6. In a communication system, a synchronous multiplex channel, .a start-stop branch circuit, synchronous telegraph apparatus operable over said: synchronous .chann'el, start-stop apparatus including "a transmitter and two signal regenerators operable over said branch circuit, means to connect'said synchronous channel to one of said signal-regenerators in accordance with the phase relationship of said-synchronous apparatus and :said start stop apparatus, and means to maintain said-connection foran integral number ofthe complete characten signal intervals.

7."In a-communication system, asynchronous multiplex channeL- a start-stop circuit, synchronous telegraph apparatus operable over said synchronous channel, start-stop apparatus including n eans ontrolled jointly by signals emitted by 35 saidtransmitter and said synchronous apparatus to selectively connecto'neofsaid repeaters ,to said multiplex channel. i

H195 In acarrier telegraph systempa plurality of communication lanes, each lane including a-main channel; aplurality 'of branchcircuits, and a mechanical distributoncomprising a set of contacts-'fQr-each' branch circuit to connect said branch c'ircuits periodically, to said main channel, variable transmission delay means in-each branch circuit; and means to determine the transmission delay'to phasetransmis'sion in any branchcircuit with its set of contacts in said distributor.

i '10:"In "'a"telegraph"system, a transmitting stationji' a ireceiving' fistation, a" communication 'line connecting saiti'f stations," means" including mechan'ical" distributorsat fboth' 'ofs'aid 'sta'tionsfor increasingthe number of communication chananswer-said line when said distributors are opcrating; ,"means for operating said distributors, and means'jfor attaining arid maintaining" syn- 'and'phase',between said distributor's,

said. last named means being responsive to contiQl "currents transmitted OVr Said communication line. h

v "11. 111 'a "teIeg apn' s stem, a "lihefconductor, a

of tsttgstopjpermutat oa code" transmitters o erat n a rand a di bu r. ha g is-r tributing contacts connected betwecn sa d lin an b t ,orsaidtrans it ers.-sa so t c s 01 leratin toconn ct said transmitters to sai li iii-alternation impulse by im uls th r creatinsrtwortra smissionhann ls, urther co ta s aid distributonand r taryphasinelmea no 0 mallylrotatingwhile transmissionxis suspended, said phasing means .beingoperative to stop. for .a'ngintegral number of :codesignal periods under the joint control.oflsaidgfurtheracontacts. and the startiimpfllse of alstart'stop.permutationacode 75 signal generated by one of said transmitters to tion dfsaid distributing contacts.-

:12. In a telegraph system, amain channel, a branch circuit, synchronous'telegraph apparatus operable over'said main channel including means to connect said branch circuit to said main'channel periodically, a start-stop permutation'code transmitter operable atirandom in said branch circuit, means operable over said branchicircuit to generate a first set of signals corresponding to the signals emitted bysaid transmitter, .means operable; over said branch circuit to. generatea secondset of signals corresponding to the signals emittedby said transmitterv but in delayed time relation to said first set of signals, means responr si-ve to the operation of said transmitter to apply one or the other of said set of generated signals .to said main channelin accordance;with;the

phase relation of said transmitter andsaidsynchronous operation, and means to maintain the application of said, set, of generated-signals to said main channel for an integral number- 0f start stop code signals;

13. In amultiplex. telegraph system, amain n e i r nc i it a td ri t tmeqh nism connected betweensaid main channeland said branch circuit to connect said channel and a c t pe io call for m ltip e erat a start-stop permutation code transmitteroperating at random in saidbranchcircuit, a repeater r in said circuit comprising areceiving magnet, to which said transmitter is connectedand two sets ofoutput contacts through either of which said branch circuit'may be er itendedto said main channel, means in said repeater to generate signals atone set of said outputfcontacts corresponding to signals emitted by' said transmitter, means in said repeater to generate signalsat the other set offsaid output contacts identical with fbut in delayed time relation to said mentioned generated signals, and means controlled dually by said d istri'bu'tor mechanism "and said transmitter to extendfsaid branch ciircuit to said main channel through' one of said sets of output v contacts in accordance with the phase relation of said transmitter'and said distributor mecha- 14. In asynchronous multiplex telegraph system, "a fir'st' station, a se ond" statioifl a telegraph circuih'colin'ecting said s'ltations'," motor driven control apparatus at saidfi'rst station, means at said first station'for cjonditijoningsaid control,

apparatus for signal transmission over saidfcir' -cuit'when said control apparatus attains a predetermined speed, control apparatus also'atsa'ijd second station, means at 'said' s'econdstation 'o'perable upon theestabli'shment of said predetermined speed for placing said control apparatus thereat into operatiomandmieans' at said second station for conditioning said control apparatus for signal reception from said circuitupon its'attainment of a speed of operation'corresponding to the predetermined speed of the control apparatus at said first station."

15. In a synchronous multiplex telegraph system, a first station, a second station, a telegraph circuit connecting said stations, motor driven control apparatus at said firststation,meansat I said first station .for conditioning'said'control apparatus for signal transmission 'ove'r sai'd cir- I phaselsaid one of transmitters'with the opera- 'minedJ-speed for placing said control apparatus thereat into operation, means at said scon'd'station 'for conditioning said control -:ipparatusior signal reception fromis'aid circuit upon itS'attaih- -ment1of a speed of'operation corresponding to the predetermined "speed of the control apparatus-at said first station; and *means at eachof said respective stations for nia'intainingsaid'con- 'trol apparatus at the predetermined speed during control apparatus at said first "station, means at said first station-for conditioning said-control apparatusfor signal transmission over said circuitwhen said control apparatus attains a predetermined speed, control apparatus also at said second station, means at said second station 0perable upon the establishment of said predetermined ;speed for placing-said control apparatus thereat into operation, means at said sec'or'idistation for conditioning said control apparatus. for signal reception from said circuit upon'its attainment of a speed of operation corresponding to the predetermined speedof the, control apparatus at said first station, and an indicating means at said first station operative when the controlapparatus thereat is efiective for communication for indicating such a condition.

17.-In a synchronous multiplex'telegraph system, a first station,- asecond station, a line connecting said stations, motor driven control apparatus at said first station, means 'at said first station for conditioning said control apparatus for signal transmission over'saidline, and means operated when said control apparatus has at- ,tained predetermined speed for operating .said

first recited meanswhereby signal transmission may be efiected over said line.

paratus at said first station; means at said first station for rendering said control apparatus effectivefor communication over said line to: said second station upon the establishment of 'a predetermined speed of said-control apparatus,-and means'at said first station for indicatingtheestablishment of such a. condition.

19,.In a multiplex'telegraph system, a communication line, a plurality of separate and distinct transmitters for generating equal *length code signal impulses, a mechanical distributor-including a pair of contacts'individual to each transmitter, means for connecting each transmitter with its pair of contacts, and cam means 'for operating said pairs of .contactsat regular intervals to connect each transmitter 'periodically to said communication line and maintainingsuch connectionfor the period required to transmit the impulses for a singlecode group from the then connected transmitter.

20. In a telegraph system, two stations, aficircuit connecting" said stations, telegraph apparatusat each of said stations, a motor at each'of said stations for driving each of said apparatuses, means-at one of said stations for placing both of said motors into operation, and means at each of said stations for conditioning said apparatus at each station for communication over saidcircuit upon the attainment of a predetermined phaserelationship between said motors; 2 :1 j j 1'31 :1 LOUIS MLPOTTS

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