US2282357A - Signaling system - Google Patents

Description

y 2, 1942- P. HOLCO MB, JR 2,282,357

' SIGNALING SYSTEM Filed Jan. 30, 1957 5 Sheets-Sheet 1 INVENTOR P. HOLCOMB JR. tIIIIIIIII +1 BY ATTORN EY May 12, 1942. HOL'COMB, JR

SIGNALING SYSTEM Filed Jan. 30, 1937 5 Sheets-Sheet 2 1 I l I I I l I l l I l l I l J.

INVENTOR R mama .N

m LW. 0 H R w May 12, 1942.

P. HOLCOMB, JR

S IGNALING SYSTEM Filed Jan. 30, 1937 5 Sheets-Sheet 3 INVENTOR F. HOLCOM B JR.

ATTORNEY May 12, 1942.

P. HOLCOMB,- JR SIGNALING SYSTEM Filed Jan. 30, 1957 5 Sheets-Sheet 4 1 m T N E V m ATTORN EY May 12, 1942. P. HOLCOMB, JR

SIGNALING SYSTEM Filed Jan. 30, 1937 5 Sheets-Sheet 5 Fmm INVENTOR E. HOLCOMB JR. Evw" gwfa-t/L 16W ATTORNEY OU A Patented May 12, 1942 SIGNALING SYSTEM Philo Holcomb, Jr., Flushing, N. Y., assignor to The Western Union Telegraph Company, New York, N. Y., a corporation of New York Application January 30, 1937, Serial No. 123,266

41 Claims.

My invention relates to signaling systems and more particularly to systems such as telegraph systems wherein a plurality of sources of signals are employed.

In my prior application Ser. No. 666,064, filed April 13, 1933, I have disclosed a telegraph system embodying the basic principle of the expanding channel system, i. e., a system in which a variable number of telegraph transmitters or other sending devices are arranged tocontrol receiving devices corresponding to each sending device over a lane of trafiic, substantially the entire lane time in the preferred system being divided among the operating transmitters. In the system illustrated in said patent the lane of traffic comprises'a single channel of a synchronous multiplex system. The expression lane of trafiic as used herein designates the route or medium over which signaling is accomplished.

It is the object of the present invention to improve and simplify the system disclosed in my above mentioned prior application and the mechanical construction and arrangement of the apparatus employed for controlling the signaling channels.

More specifically, an object of the invention is to provide an expanding channel system in which the lane time, or a predetermined part thereof, is divided either equally or unequally, as desired, between the transmitters having mes sage signals to transmit over the lane of traific If only a few transmitters are operative, the capacity of the lane of traffic may be greater than the capacity of the operative transmitters, and

in that event it is desirable to slow down the transmission over the lane of trafiic sufficiently so that the operating transmitters function properly. It may also be desirable to render certain transmitters incapable of seizing a subchannel of the lane of traffic when a predetermined number of other transmitters are operative, as for example where certain transmitters are allocated to deferred messages and the deferred traflic should be held up until the regular traflic is below a predetermined amount. In accordance with a preferred form of the invention, certain transmitters or channels are only operative when less than a predetermined number of other transmitters are sending over the lane of traffic.

Another object of the invention is to provide an expanding channel system in which certain channels have constant speeds or transmitting rates. In the usual expanding channel system operating channels share the lane time equally and thus the speed of transmission for each channel varies depending upon the number of other channels in operation. In some cases, however, it may be desirable to have one or more channels operate at a constant speed irrespeca multichannel telegraph system in which multiple character transmitters are employed, namely, transmitters from which two or more characters are sent during each cycle of operation. This feature of the invention permits a higher speed of transmission from the channels when only a few channels are in operation and likewise permits the lane to be operated more nearly at full capacity when only a few channels are in operation.

Another object of the invention is to provide an expanding channel system utilizing a pluralchannel multiplex as the lane of trafiic and arranged to transmit from a subchannel simultaneously over a plurality of the channels of the multiplex system.

Another object of the invention is to provide an expanding channel system wherein the entry and/or exit signals for cutting the receiving devices in and out consist of multiple character code combinations, such as two or more successive characters which together constitute an entry or exit signal; and a system wherein the component parts of the entry and/or exit signals are sent over different multiplex channels thereby reducing the possibility of the occurrence of false entry or exit signals as the result of line trouble.

Another object of the invention is to provide an expanding channel system utilizing a plurality of synchronous multiplex channels in which the entry and/or exit signals are invariably sent over one only of the multiplex channels. One advantage of this arrangement is that code combinations used forregular message characters may be employed as entry or exit signals.

Another object of the invention is to provide an expanding channel system in which ordinary code combinations are employed as entry or exit signals and in which, when said signals are originated from a transmitter instead of from the control apparatus, they are momentarily deferred or converted into other signals or both.

Another object of the invention is to provide a governor for controlling the speed of opera tion of the control equipment whereby when only a few transmitters are operative, the transmission rate over the lane of traffic is reduced in accordance with the capacity of the operative transmitters.

Another object of the invention is to provide an expanding channel system in which certain channels are only operative under predetermined system conditions as when the number of other channels, such as preferred channels, in operation is fewer than a predetermined number whereby deferred traffic may be held up until regular trafic is below the capacity of the lane of trafiic.

Another object of the inventionis to provide in an expanding channel system a simple andv effective arrangement for metering the trafii'c in each channel or means arranged. to provide. a basis for rendering equitable charges for service in a system of this character.

Another object of the invention is to provide in connection with an expanding channel system means, for signaling over the channel, as: for example for the purpose of, operating a signal to call an attendant at a remote station, and

means for controlling the system, as, forexampie to stop transmission from a distant station or 013368.

Another object of the invention is to provide an expanding channel systemin which the'maximum number of operating channels is substan-: tially constant.

Another object of the invention is to improve the method of entry in a system which does not require the exclusive use of a code combination for, an entry signal; and in which accidental entry or exit of a channel, as a, result of line trouble is obviated.

Other objects and advantages of the invention will become apparent from the following description of the systems embodying, the invention shown on the accompanying drawings. Referring 1 to the drawings,

Figs. 1, 2 and 3 are views, part1y;diagra mmatic,

of a system embodying the invention, Eigsland 2 illustrating the circuits and; apparatusof the transmitting station and Fig. 3, the circuits and.

apparatus at the receiving station;

Figs. 4 and 5 are similar views of -a modifiedsystem embodying the invention;

Fig. 6 is a detail view of a, modified.form-, of stop or latch member; and

Fig. 7 is a detail view of an element of themixer.

Referring to Figs. 1, 2 and 3 of thedrawing,

the system illustrated is an expanding channel system utilizing a four-channel or: quad-multiplex as the lane of traffic. The transmitting distributor of the synchronous multiplex at the first station is indicated at TD in Fig. 1 and the receiving distributor at the second station at RD in Fig. 3.

the relay bank IF comprising ten relaysiin the casaof a five-unit. code) hayingarmatures ll toiilv connected through the armatures of relay;

The distributors are interconnected, through the line circuit L arranged for duplex.

25 to the segments of channels A and B of the transmitting distributor TD or through the armatures of relay 26 to the segments of channels C and D of said distributor, depending upon Whether relay 25 or 26 is energized. The relays 25 and 25 are connected to segments 2'! and 28 respectively of the local ring St of the transmitting distributor TD in such a manner that the relays are alternately energized whereby the characters stored in relay bank it are alternately transmitted over first one pair and then the other pair of channels of the transmitting distributor.

The operating windings 3! of the relay bank It are multipled to the contacts of the transmitters of the respective channels of the system, such as the tape transmitters 3'5, 3'5, 3?, 38, 39 and 40. The tape transmitters may be similar in construction to that shown in patent to Benjamin No. 1,298,440, dated March 25, 1919, except that transmitters 35, 3 5, 3i and 38 are provided with ten selecting contacts and the stepping magnet of each transmitter is arranged to step the tape two characters at a time whereby upon each cycle of operation, each transmitter is arranged to actuate relays of relay bank in in accordance with the code combinations representing two successive characters perforated in.

vided with operating windings 33 for a purpose to be hereinafter described.

The transmitter 36-is automatically entered'on.

the-lane of traflic upon theclcsure of the autostop contacts 45 controlled by the tape loop adjacent the-transmitter. Each of the other transmitters is likewise entered under the control of its associated autostop contacts. The autostop contacts 45 are in series with one-half of the winding of the usual autostop relay 45, the midpoint of said winding being connected in seriesv with the stepping magnet of the tape transmitter 36. I The autostop relay 46 isnormally energized:

when the associated'tape transmitter is inoperative as indicated'by the opening of the autostop contacts 45 upon the shortening of the tape. loop, the relay beingloclred upin series with'thestepping magnet of the tape transmitter through.

its front contact 47 to ground. Upon the lengthening of the tape loop and the resultant closure of the autostop contacts a5, a parallel circuit is, closed to ground through the left hand half of thewinding'of relay dfi'and the contacts 45 to ground at the contact'dt oi the transmitting'mixr er TM. The autostop relay 46 becomes deenergized, the described circuit to ground through the contact 41 is opened and thejrighthandhalf of the winding of relay dii-isconnectedto ground 1 through the contact 49 and the above described contact 58 of the transmitting mixer. Thereupon a circuit is closed through the right hand outerarmature and back-contact of the autostop relay it for entering the, transmitter upon the lane -of traflic in a manner to, be described;

The transmitting mixer TM comprises 'a rotate-i,-

able and axially movable arm 54 driven through a friction clutch 55 and lying normally in the plane of a depressed stop bar or latch member 56 having two operative positions corresponding to the channel in and channel out conditions. Each of the transmitters is provided with a similar latch member 56, 55a, arranged peripherally around the plane of rotation of the mixer arm 54, each of said latch members being adapted to be depressed into the path of the rotating arm to enter the associated transmitter on the lane.

Assuming that the stop or latch member 55 has been depressed into the position shown in dotted lines in Fig. 2, in a manner to be hereinafter described, it will be apparent that the rotation of the mixer arm 54 will be stopped by the engagement of said arm with the inner end of said member. When the local brush 68 engages segment or 62 of the local ring 63 (depending upon whether the previously connected subchannel was connected to channels A and B or C and D of the transmitting distributor), a circuit is closed from battery through the conductor 64, the right hand armature and back contact of relay 65, the winding of magnet 16 and the normally closed contacts of relay ll to ground whereupon the magnet momentarily depresses the mixer arm 54 to release the same from the latch member 56. As the arm 54 commences to turn in its lowermost position, it engages the inner end of the pivoted contact 48 which is mounted behind the latch member 55 thereby momentarily opening the circuit of the stepping magnet of transmitter 36, said circuit including contacts 45 of the autostop, contact 45! of relay 45, the winding of relay 45, the operating magnet of meter and conductor 16. The meter or integrating means 15 may be a conventional electromagnetic register having counting Wheels operated by the successive energization and deenergization of the operating magnet as the associated transmitter is periodically rendered operative, thus registering the number of message characters sent from the transmitter. The registration of the meter or accumulating register 15 provides an equitable basis for billing the customer in accordance with the actual service rendered and avoids the difficulties encountered in the prior systems, such as timed-wire service and the like.

This metering or service-charge arrangement is an important feature of the invention as heretofore charges for telegraph service rendered to customers having printing telegraph apparatus were based upon the time during which a communication channel was furnished as the customer utilized the facilities of the telegraph company all of the time whether actually transmitting a message or not. In the expanding channel system however, a channel is only occupied during the time when the customer is actually sending and therefore charges may be based upon the number of characters or words transmitted. The advantage of this arrangement from the customers standpoint is obvious. In order to meter the service on a word basis, the counter 15 may be arranged to be operated in accordance with the frequency of the transmission of spaces between words.

When the stepping magnet of the transmitter 35 is deenergized as described, the feeler pins of the transmitter are projected against the tape and the transmitter contacts are selectively operated in accordance with the characters perforated in the tape.

The contacts which are operated into engagement with the left hand or marking contacts of the transmitter close circuits through corresponding operating windings 3| of relay bank I0 whereby the code combinations are set up in the relay bank. The breaking of the circuit of magnet 10 by the continued movement of the brush 6!] releases the mixer arm 54 which rises above the contact arm 48 and rotates into engagement with the latch member of the next channel which is cut in. The contact arm 48, being biased to closed position, recloses the circuit of meter 15 and of the stepping magnet of transmitter 36, whereupon the feeler pins of the transmitter are withdrawn from the tape and the tape is stepped to present the next two characters to the pins.

Upon the completion of the revolution of the mixer arm 54, the stepping magnet of the transmitter 36 is again deenergized by the actuation of contact arm 48 whereby the transmitter 36 is rendered operative to send two characters over the lane of traflic for each revolution of the mixer arm 54 as long as the stop or latch bar 56 is depressed. Likewise the mixer arm, during such revolution, causes the other transmitters which are cut in by the depression of their latch members corresponding to member 56 to be rendered operative in a predetermined order one after the other, the transmitters having nothing to send being passed over by the mixer so that they do not occupy any lane time.

The two characters sent by each transmitter during its operative cycle are set up on the contacts of relay bank l6 comprising ten polar relays each having, two unbiased armatures which remain in their operated positions. The arma tures l l, 2-4245 are arranged to transfer the code combinations received from the respective channels in response to the operation of the mixer alternately to channels A and B of the transmitting distributor TD represented by the first ten segments of the transmitting ring 65 and to channels C and D represented by the eleventh to the twentieth segments of said ring, the changeover from one pair of multiplex channels to the other being efiected by relays 25 and 26'. The polar relays 24 having their respective armatures connected to the segments of transmitting ring 65 are arranged to store the code combinations from relay bank It and impress marking or spacing potential on the segments of said ring so that the characters to be sent over channels A and B of said ring may be set up while the transmitting brush 6! is travelling over channels C and D, and vice versa. As shown, the marking potential of channels B and C is reversed with respect to channels A and D in order that transmission cannot be efiected if the transmitting and receiving distributors are accidentally shifted or 270 out of phase, the out-of-phase relation being apparent from the distorted signals received. Obviously any other out-of-phase condition also interrupts communication. V

The transmitters of the respective channels of the expanding channel system may be of any type adapted to operate in conjunction with the lane distributor and are preferably adapted for operation in accordance with characters stored in a tape or other storage medium under the control of the mixer. Each transmitter may be located in a patrons office and adapted to receive tape from a keyboard perforator or may be in the telegraph oilice and associated with a reperforator controlled from a keyboard transmitter in a branch ofiice or patrons office.

When the transmitter 36 has completed the transmission of the message characters perforated in the tape, the channel is automatically disconnected from the lane of trafiic and the lane time is divided between the operating channels.

The shortening of the tape loop opens the autostop contacts at whereupon the autostop relay 46 becomes energized and locks up in series with the stepping magnet of the transmitter 36, the locking circuit including the inner armature and contact 41 of said relay. After the message characters stored in relay bank ID from the channel gized as during transmission from this channel.

since the stepping magnet is locked up through contact 4'! of the autostop relay. Thus the armatures of rela bank Ill remain all spacing and the double-character 'ezrit signal in which both characters comprise five all-spacing impulses (blank character) is sent over the lane of traffic to cut out the receiving device of this channel in a manner to be described. The armatures.

H'--2G of relay bank in constitute baflle circuits which are completed when the entry and exit signals are set up in the bank. Thus when the armatures il'-2ii' are all operated to spacing and remain in these positions after the mixer arm t has operated the contact arm 48 on account of the energizaticn of autostop relay 45 as described, a circuit is closed from battery through the armatures ll, I2, [3, I5, I 6, l1, i8, 25', I9, and their respective spacing contacts, conductor 30, cut-out magnet SI of the transmitting mixer TM, conductor 92, spacing contact and armature M to ground whereupon magnet Si is energized. The energization of magnet 93 depresses the arched central portion of a leaf spring 53 carrying an ofi'set lug 94, thereby moving the lug 94 underneath the end of the latch member 56 so that as the mixer arm 54 carrying the spring 93 rises, the latch member is raised to the position shown in full lines in Fig. 2 and the associated channel is cut out. As the mixer arm 54 rotates, the remaining channels are cut out at the completion of each message in the same manner by the properly timed energization of magnet 9|. The stop or latch members 55, 55a, etc., are preferably biased against both upper and lower stops by a spring toggle device so that the cut-in and cut-out mechanism is onl required to actuate the members past the central point of their travel.

The entry of each channel upon the lane of traii'ic as soon. as a channel has message characters to transmit is effected automatically in response to the closure of the autostop contacts 45 as a result of the lengthening of the tape loop from the associated perforator or reperfo rator. In order to efiect the simultaneous entry of a transmitter at the sending station and a receiving device at the receiving station, a transmitting clock TC at the sending station and a receiving clock RC at the receiving station are provided. The transmitting and receiving clocks comprise contact arms and respectively, rotating at the same speed; for example, said arms may be geared to or controlled by the transmitting and receiving distributors of the synchronous multiplex system. As shown, the transmitting and receiving clocks also comprise rotating cut-in bars 8! and Edi which are also maintained in synchronism. The contact arm 80 of the transmitting clock is provided with brushes bearing upon segments 82 and 83 and upon a contact ring M extending around the periphery of the clock. Each channel is provided with a pair of segments such as the segments 82 and 83 and the receiving clock is similarly provided with pairs of segments for each channel arranged in the same order as the segments of the transmitting clock.

Upon the closure of the autostop contacts A5, as'a result of the lengthening of the tape loop, a circuit is closed from ground through the contact arm 18, the autostop contacts G5 and the left hand half of the winding of relay 46 which is in parallel to the circuit through the right hand half of the winding of said relay, and the autostop relay at becomes deenergized, thereby opening the locking circuit through contact d! but closing a parallel circuit through contact 49 to the ground at contact arm 48, of the transmitting mixer. Upon the deenergization of relay M a circuit is closed from segment $2 of the transmitting clock TC through the outer armature and back contact of relay at to ground at the stop or latch member 56 through the upper contact which is in engagement with said latch member. When contact arm 30 of the transmitting clock reaches segment 82, the circuit is closed from the grounded segment 82 through contact ring 84 and the winding of relay 56 to battery, whereupon relay (it becomes energized. When the contact arm 89 engages contact segment 83, a locking circuit is provided through the latter segment and the left hand armature and front contact of relay 66 whereby said relay is maintained energized for a sufiicient time to insure the cutting-in of the channel.

The energization of relay 5-8 closes a circuit from local segment i?! or 52 when the local brush ti reaches one or the other of these segments through conductor 54, the right hand armature and front contact of relay 6%, conductor 95, coils of the fourth and ninth relays of relay bank id and conductor 93, for energizing cut-in magnet 9? or" the transmitting clock. The energization of magnet fil depresses the outer end of the cut-in bar 8% of the transmitting clock which at this moment is positioned above the stop or latch member 5% thereby actuating said member to its lower or channel-in position. At the same time, as a result of the energization of coils 33 of relay bank it, the entry signal is transmitted from the relay bank it to one pair of the channels of the transmitting distributor TD and the remote receiving device is out in upon r ceipt of this signal in a manner to be described. It will be noted that the diversion of the local pulse from local ring 133 which normally energizes the magnet it of the transmitting mixer prevents the transmission of characters from the channel which has been selected by the mixer arm 55 so that the transmission from this channel is delayed during the time required for sending the entry signals over the lane of traffic. Upon the next operating cycle, however, the characters which have been heldup will be transmitted, since the mixer arm 54 has not been released from the stop member of the channel which it had selected.

In the embodiment of the invention illustrated, the double entry signal consists of two characters in which the fourth impulse is marking and the remaining impulses spacing (carriage return character). The energization of coils 33 of the fourth and ninth relays of relay bank It operates the armatures of the fourth and ninth relays to marking, the remaining armatures of the relay bank having been actuated to spacing by the restoring windings 32 in the manner described above.

The double entry signal consisting of two code combinations having the fourth impulse marking has been selected because this selection is ordinarily employed for carriage return and if used at all, need not be transmitted twice in succession. Obviously, any desired code combination may be utilized as the entry signal although it is preferred that an entry signal be employed which is not normally used or at least is not required for regular communication. Another useful signal would be an upper case code combination such as figure shift followed by F.

Referring to Fig. 3, the receiving distributor RD at the receiving station comprises a receiving ring I69 having the respective segments thereof connected to the windings of the relays of receiving bank II), and local rings III and II2. Each of the relays in the relay bank I! IS a polar relay having two unbiased armatures adapted to remain in engagement with corresponding marking or spacing contacts after each impulse until the reception of an impulse of opposite polarity from the line relay. In this manner the code combinations received over the line are stored upon one set of armatures and the other set is arranged to close bafiie circuits when the entry and exit signals are received.

The cable IZE which is multipled to the receiving reperforators or other receiving devices comprises ten conductors which are connected through the armatures of relay I2I alternately to the right hand armatures of the first ten relays of relay bank II 8 and to the right hand armatures of the remaining (11th to the 20th) relays of said bank. The relay I2! is energized as long as the distributor brush of the local ring I I2 remains in engagement with the segment 122 of said ring whereby the code combinations set up on the second half of the receiving relay bank are connected through the cable I243 to a receiving device while the receiving distributor brush is resetting the first ten relays of said bank, and the last mentioned relays are connected through the back contacts of relay I2! and the cable I2!) to another receiving device while the receiving distributor brush is resetting the eleventh to the twentieth relays of said bank in accordance with incoming signals.

The ten selecting windings of a reperforator,

55 clocks move on to the next point of entry which printer or other receiving or storing device, are represented at Mt, said windings being connected to separate contacts M1 adapted to be simultaneously connected to battery by the pivoted normally open contact member I48 when the latter is engaged by the mixer arm I54 of the receiving mixer RM. If a ten-unit reperforator is employed, it may utilize a wi. e tape or be arranged to step the tape two characters during each cycle of operation. The normally open circuits of the other receiving devices are similarly controlled, when the channels are cut in, by the mixer arm I54 under the control of the stop bars I56, I55a, etc. In general, the construction and mode of operation of the receiving mixer RM are 5 similar to the construction and mode of operation of the transmitting mixer TM, the stop bars I56, I551; being depressed from the position indicated in full lines when the channels are cut in and the mixer arm I54 selecting the operative receiving channels one after the other in the same order and at. the same time (taking the transmission lag into account) that the mixer arm 5 of the transmitting mixer selects the corresponding transmitting channels. The receivl5 ing devices of the operative channels are operated by momentarily closing the circuits, by the contact member MS, of the selecting windings Hi5 and of the operating magnet M9 to print, store or perforate the characters set up at that instant on the connected group of relays of the receiving bank H0.

As has been described above, the entry signal which is transmitted over the line to enter a receiving device on the expanding channel sys- 5 tem comprises two successive characters, each having only the fourth impulse marking (double carriage return). This signal may be sent over either channels A or B or channels C and D depending upon the time when the clocks TC and RC reach a subchannel which is to be cut in.

Assuming that the entry signal is received on channels A and B of the receiving distributor represented by the first ten relays of the receiving bank i It, as the brushes of the receiving dis- 35. tributor continue to travel, the circuit of relay ceiving bank H0, a circuit is closed through the upper armature and back contact of relay IZi, through the left hand armatures and ,marking contacts of the fourth and ninth relays of relay bank I It, the spacing contacts of the first, second, third, fifth, sixth, seventh, eighth and tenth relays of bank I Hi, through the winding of relay I24, brush arm I and segments I82 and H84 of the receiving clock, upper contact I35 and the stop bar I56 to ground, whereupon g relay I23 becomes energized,

It will be noted that this circuit is only closed upon the transmission of the entry signal and the position of the brush arm I89 of the receiving clock when said signal is received determines 5 the receiving device which is. to be entered on the channel, said device corresponding to the transmitter 3%, Fig. 1, in this instance. The selection of the proper receiving device or channel is thus determined as stated above by the 00 time of transmission of the entry signal. A

short signal with interspersed trafiic signals is thus operative to select any one of a large number of channels. The lane of trafiic is utilized for message signals While the brushes of the may be hundreds of message characters farther on. The significant lapse of time to effect proper entry is not wasted.

Relay I24 remains locked up through the segys ment I83 of the receiving clock, the latter circuit including the left hand armature and front contact of said relay. On the continued move-i ment of the brush arm of the receiving distributor RD, a circuit is closed through the :5 local segment I26, the right hand armature and front contact of relay I24 and the entry magnet I91 of the receiving clock RC. At this moment the cut-in bar I8I oi the receiving clock is above the outer end of the stop bar I56 and the tilt-i ing of the cut-in bar I8I depresses the latter; as described in connection with the transmitting clock TC. The stop bar I56 is thus depressed to the position shown in dotted lines representing the channel-in position. As soon as the brush arm Hill of the receiving clock RC leaves the segment I83, the locking circuit of relay I22 is interrupted and the relay is restored to normal. During the time the relay I24 was energized, the circuit of the operating magnet IIIJ of the receiving mixer RM was interrupted at the right hand armature and back contact of said relay, thereby preventing release of the mixer ar-m I54 from the stop bar with which it was engaged.

In this manner the characters forming the 7 entry signal on channels A and B are prevented from reaching a receiving device and the transmitting and receiving apparatus is maintained in synchronism since, as has been described above, transmission of regular character signals over the lane of trafiic is momentarily interrupted during the transmission of the entry signal. If the entry signal had been received on channels C and D of the receiving distributor, the operation would have been substantially as described except that relay IZI is energized when the local brush of the distributor engages segment I22 of the local ring I82, and the baffie circuit for reading the entry signal comprises upper armature and front contact of relay I2I and contacts of the eleventh to the twentieth relays instead of the first to tenth relays of relay bank IIIJV Upon the subsequent engagement of the mixer arm I 5 with the stop bar I55, the selections stored in one half of the receiving bank III are connected through the contacts of relay IZI to the windings I of the receiving device which,

is operated by the closure of the contacts it! and I 33 when the mixer arm I54 is depressed beneath the stop bar I 56 by the magnet I'It. The circuit of the magnet I10 includes the stop bar 156, the lower contact I81 engaging said bar, the right hand armature and back contact of relay I24 and segment IE5 or I21 of local ring III of the receiving distributor RD. Each of the receiving channels which has been out in is thus rendered operative concurrently with the corresponding one of the transmitting channels connected successively to the lane of traflic under the control of the transmitting mixer TM irrespective of the number of operative channels, the entire lane time being divided among the operating channels when more than a predetermined number of channels are operative.

It is desirable in a system of this character to provide auxiliary signaling or control channels in addition --to the channels used for communication; These auxiliary channels may be employed for various purposes such as signaling between the attendants at the respective offices or for controlling the operation of the equipment in any desired manner. Thus if difficulty is experienced in reception at one office, it may be desirable to direct the attendant at the remote oiiice, to stop transmission into that ofiice. If desired, the control channel may be .used, for example, to stop the apparatus and reconnect the operative channels one by one from an inoperative condition to insure that the lay bank It.

same number of transmitting and receiving channels are in operation. In the system shown, the signaling or control channel is provided with space on the transmitting mixer, as in the case of each of the communication channels, and the control device is a key switch 38 having contacts controlling the entry circuit corresponding to the outer right hand armature and corn tacts of the autostop relay it, the key being provided in addition with contacts arranged to connect marking batteryto the operating winding 3| of the first relay of the transmitting re- Other keys could also be arranged to transmit code combinations for effecting different functions at the receiving end of the circuit in the same manner as the key 88. When one of the keys is operated, the signaling chan nel is entered in the same manner as one of the communication channels and thereby causes the entry of the receiving signaling channel represented by the windings lt l. Windings It'll! may represent separate polar relays arranged to be operated in accordance with the application of marking or spacing potential upon the respective receiving relays under the control of the contacts of the relays of the relay bank Iiil in accordance with the adjustment of the control key switches. For example, the first relay I68 connected to conductor No. l of cable I 20, and corresponding to key 88, is provided with a series of armatures I6I arranged in series relation with the autostop relays associated with the transmitters at the second station, Fig. 3, which are intended for transmission to the first station shown in Figs. 1 andZ (as shown in Fig. 2, contacts 89). In this manner the operation of the first relay Hill in response to marking battery upon conductor No. 1 of cable I21! will open the autostop relay circuits of the transmitters at the second station and thereby efiect disconnection of all of said transmitters from the expanding channel system. When the control key at the first station is again restored, the distant autostop circuits of the operative transmitters would be reclosed and after the transmitters were entered on the lane 'of traffic in the usual manner, transmission would be reestablished. The receiving station of Fig. 3 would also be provided with a signaling channel or channels for stopping transmission from the station shown in Figs. 1 and 2 and for an other desired purposes. For example, the application of either marking or spacing battery, as desired, upon any one of the other windings Hill could be arranged to operate signals or effect other functions at the remote station.

In accordance with a further feature of the invention, transmission from certain of the transmitters may be made dependent upon the operation of the other or regular channels of the system. Thus, for example, the transmitters 31, 38, 39 and 30 may be deferred traffic transmitters and arranged to seize a channel of the expanding channel system only when less than a certain number of other or regular channels are in operation. The deferred channels may be precisely the same as regular channels except that a relay contact 891, 892, etc. of relay I3 is inserted in each of the autostop circuits of these transmitters which will bid for entry or exit. of the deferred channels when the number of regular channels reaches a certain figure. Transmitters 39 and 40 having different tapes are fiveunit transmitters arranged to operate in unison on one expanding channel. Corresponding fiveunit receiving devices may be employed.

The respective contacts 81 associated with the stop bars 56, including those of deferred channels, of the transmitting mixer TM are connected through separate resistances 12, the common terminal of said resistances being connected in series relation with windings of relays 85, II and 13. It will be apparent that the current through said relays varies according to the number of channels which have been cut in. The relay 85 is adapted to close a contact when the number of operative channels is less than three. Similarly, the relay TI is adapted to close a contact when one or more channels is cut in, and the relay 13 is arranged to close the autostop circuits of the deferred or special transmitters 37, 38, 39 and 40 only when less than four regular channels have been entered. The contacts 891, 892, 393 and 894 are in series relation with the autostop contacts in a manner similar to the contacts 89.

When no channels are cut in, relay 1! remains on its left hand contact, mixer arm 54 spins freely without being depressed by the armature of magnet 19. When any stop bar such as stop bar 56 is lowered to the channel-in position by clock armature 8!, a circuit is established through the operating winding of the relay ll, resistance 12, ground and battery, which will overcome the spacing bias of relay H and close the ground circuit of mixer operating magnet 19. Thus the selector arm of the transmitting mixer resumes its regular function when the first channel is entered upon it. If several channels are in operation at once, the speeds of the various expanding channel transmitters are comparatively slow. Let us assume that three channels of the first station give a satisfactory rate of operation for each channel, even though the multilever transmitter were capable of keeping the circuit completely full. In that case the one busy operator would find it extremely diflicult to keep the line full of traffic, and therefore it is desirable to permit deferred transmitters to share the lane when fewer than a certain number of regular transmitters are cut in at any time. When less than three of the regular transmitters are cut in. contacts of relay 85 close on account of the reduced current through the operating coil. This applies a ground to the segments corresponding to segment 82 of the transmitting clock TC through added contacts of the autocontrols on the various expanding channels which are cut out at the time. These cut out channels are therefore entered again and since the transmitting mixer TM does not step to a new position during the entry function, the rate of transmission is curtailed, to that extent constituting a kind of governor device on the regular channels which remain in. operation. The channel which has nothing to send but which is cut in in the aforesaid manner by the o eration of the relay 85, remains entered until it has opp rtunity to send one all-spacing combination. This removes it from the sequencing cycle but another idle channel is immediately entered to take its place.

The successive entry and exit operations performed on the idle channels govern the speed of the regular operating channels until the necessity for entry occurs at a time when the brushes of transmitting clock TC are on segments corresponding to 8?. for one of the deferred channels 31, 38, 39-49. It is assumed channels.

that prepared tape is'in place over the pins of the deferred channels and when the opportunity for entry comes to these channels, transmission of deferred traffic commences and is maintained until the cutting in of other channels increases the total number of channels cut in to four or more. At this moment, due to the preponderance of operating over biasing currents in relay 13, the autostop circuits of the deferred traiTlc transmitters controlled by this relay are broken, thus initiating the exit cycle of these transmitters, and suspending operation until the cut-in cut-out situation is again favorable for the transmission of deferred traflic.

Deferred trafiic transmitters 39 and 49 are of the standard five-contact variety and though employed in transmission of two separate messages, their magnets are in series and their operation is in all respects equivalent to that of the transmitters 3'! and 38. At the receiving end the devices for receiving impulses transmitted by the transmitters 39 and 40 may be the usual five-unit printers or reperforators, both connected to one group of contacts of the receiving mixer. The governing action of relays 85, H and 13, and their associated circuits need not be repeated at the receiving end in connection with receiving mixer RM and receiving clock RC as the time consumed in cut-in and deferred chan nel functions are identical in all respects with those employed for the operation of the regular In systems embodying the invention various lanes of traffic may be employed and where multiplex channels are employed a a lane of traffic, more or less than four channels may be utilized if desired. The multiplex channels may utilize two or more lines or carriers to transmit the signals from the sending distributor to the receiving distributor in a manner well known in the art. Furthermore, other methods of efiecting entry and exit of the channels from the expanding channel system may be employed without departing from the scope of the invention, and various methods of governing the speed of the transmitters may be employed. Figs. 4 and 5 illustrate a modified system embodying the invention utilizing a mixer and clock somewhat similar to those shown in Figs. 1 to 3 but entry and exit of a transmitting channel are both effected by the same signal; that is. if a channel is in it is cut out when the signal is transmitted and if it is out. it is cut in by the same signal. This signal may be any character in the alphabet and need not be one exclusively devoted to these functions. Furthermore, in this system the lane of trafiic comprises two multiplex channels and the entry and exit signals are always transmitted over the A channel, Other modifications in the detailed arrangement of the apparatus will appear from the following description. but it is to be understood that the system merely illustrates certain modifications coming within. the scope of the invention by way of example, and many other changes may be made in the circuit arrangement and construction of the apparatus. including the structural details of the mixer and clock. or other means for controlling the entry and exit of the channels and the mixing of the operating channels, without departing from the scope of the invention.

In the system shown in Figs. 4 and 5, two multiplex channels are represented by the ten segments on the transmitting ring 295 of the transmitting distributor TD, the entry and exit signals being sent over the A channel represented by the first five segments of ring 2-55 in a manner to be described. The same signal is employed for entering and for disconnecting a channel and this signal is the line feed character having only the second impulse marking although other entry and exit signals may be employed if desired. This use of: line feed or other character as an entry or exit signal does not interfere with the normal usage of that functional character in communication. Any other code combination such as the letter K, figures shift or even a blank may with proper arrangement of the circuits be utilized as an entry and exit signal.

As shown, the transmitters, of which one is represented at 235, comprise the usual five-unit tape transmitters or other suitable storage transmitters of known construction. Each transmitter is connected through contacts corresponding to the contacts C of the transmitting mixer TM and the armatures of a transfer relay 225 to the first or second half of the storage relays 23! of relay bank 2 l associated with the respective channels of the transmitting distributor TD. The first five relays 23! are provided with auxiliary windings i 232 to provide for the transmission of entry and exit signals over the lane of traflic under the control of the transmitting clock TC when a channel is to be cut in or cut out. Relays of the relay bank 2H! are provided with armatures for controlling the application of marking and spac ing battery to the respective segments of the transmitting distributor and the first, third, fourth and fifth relays of said bank are also provided with armatures for a purpose to be described hereinafter. While only one transmitter or channel is shown in connection with the transmitting mixer TM, it will be understood that a plurality of channels are controlled in accordance with the operation of said mixer as in the system shown in Figs. 1 to 3. Similar partsof the transmitting clock and multiplex distributor have been given the same reference numerals as in Figs. 1 and 2 with the prefix 2 in order to assist in explaining the operation of the system as compared with the system shown in Figs. 1, 2 and 3. Likewise in Fig. 5 the elements of the receiving end of the channels have been given reference characters similar to those employed in Fig. 3 with the prefix 3.

Assuming that all channels are cut out and the flexible auto-stop levers lifted by short tape loops, the stop bars 256 of all of the channels are in the raised position as shown in full lines in Fig. 4.

It is assumed that the rotating elements 254 and 2M of the transmitting clock TC are in synchronism with the corresponding elements of the receiving clock RC, Fig. 5, and that the transmitting and receiving multiplex distributors are in synchronism. The mixer arm 254 at one point in its rotation will engage a governor stop bar 219 as shown in the lower portion of Fig. 4. The governor stop bar 278 is arranged to be lifted by a magnet 2' from the path of the mixer arm 254 only when the arm 254 is in the vicinity of the stop bar 2'30 and the brush arm 272 of the governor timer is in the zero position as shown. The brush holder assembly of the governor timer is provided with five stop arms or notches adapted to be engaged by a latch member 273 controlled by a magnet 214. The circuit of the magnet 214 includes the timer brush arm 212, a ring contact 275 and segments 276 or 211 of the local ring 218 of the multiplex distributor TD. With this arrangement it will be apparent that each impulse from the local ring 2'58 will release the timer brush arm 2l2 for one step. The timer also includes a contact 279 arranged in series relationwith the magnet 21! whereby when the timer brush arm 272 engages segment 279, the magnets 2H and Z'M are energized concurrently provided the circuit is closed to battery through the contacts 2% which are arranged to be operated by the passage of the mixer arm 254 and maintain closed as long as the arm 254 is stopped by the stop bar Zlil. This raises the governor stop bar 278 and permits the mixer arm 254 to continue to revolve. Thus the mixer arm is prevented from rotating faster than the timer brush arm 212, the speed of which is controlled in accordance with the rotation of the brushes of the transmitting distributor TD,

The purpose of this arrangement is to control the rotation of the mixer arm 254 of the transmitting mixer when less than a predetermined number of channels are in operation. Thus with the arrangement shown, if only one channel is in operation, on account of the connection of the timer to the segments of the local ring 2'18 of the transmitting distributor TD, the operating channel is not again connected to the system until the time of transmitting three additional characters over the multiplex channels has elapsed. It is obvious that the rotation of the timer brush arm 2'52 is dependent upon the number of stop arms employed and when it is desired to set a lower maximum speed for the mixer arm 2%, additional arms would be added to the timer brush arm. In this manner the number of operations of the transmitting apparatus in a definite period is limited so that it will not be necessary that one transmitting unit would be operable at a speed sufiicient to fill the lane of traffic requiring perhaps two or three hundred words per minute, if that is undesirable. With the governor the maximum speed of operation of any channel can be held quite close to the limit for which it is designed even if the speed of the circuit is substantially higher than the channel speed.

Likewise it will be noted that by the proper allocation of channels into the preferred and deferred groups and by properly regulating the relay biasing circuits, the speed of the preferred channels may be held substantially constant irrespective of the number of channels having messages to transmit. This result is accomplished by limiting the number of preferred channels in the system and properly adjusting the biasing circuits of relays l3 and so that there is'no substantial increase or decrease in the operating speed of the preferred channels whether one or all of said channels are operative. In order to fill the lane of traffic, there will or course be great changes in the operating rates of the de ferred channels. In this manner a group of constant speed preferred channels can be obtained which is desirable for transmission of market quotations, press, et cetera.

It is also obvious that the stop arms of the timer can be detachable or variable in number to vary the rotative speed of the timer brush arm 212 in case the transmitting speed of the lane of trafiic varies from day to day. On the other hand the-full capacity of a high speed lane of tranic is utilized at any time when several channels are in operation without causing difdculty when the number of channels decreases. If the multiplex were operating at one hundred words per minute per channel, a single operating transmitter would not exceed fifty words per minute with a timer brush arm having five rest positions. If one, two, three or four transmitting channels were operating, the speed would remain fifty words per minute for each channel. If five transmitting channels are in operation, the speed of the lane which is two hundred words per minute would provide a channel speed of two hundred divided by five, or forty words per minute. When above a predetermined number of channels are in operation, the approach of the mixer arm 254 will close contacts 299 and energize magnet 21I to raise stop bar 210 and permit unimpeded passage of the mixer arm.

The mixer arm 254 does not go beneath the stop bar 210 as in the case of an ordinary channel stop bar. The bar 210 must be raised to release the mixer arm. When the operating pulse depresses the mixer arm 254, the contacts HI and 292 of the governor are operated without disturbing the closed condition of contacts 290 and the relays of relay bank 210 are thus controlled from the governor to transmit the space character over the line circuit (only the third impulse marking). These contacts 29l and 292 are not essential for ordinary operation but may be desirable under certain other conditions. It will be obvious that contacts 29! and 292 may be arranged like contacts C to connect a transmitter having deferred traflic to the relay bank 2 l0.

When sufficient tape accumulates on any channel, for example at the transmitter 235, the autostop contacts 245 are closed and the channel is entered on the expanding channel system in response to this operation. Thus when the autostop contacts 245 close, a circuit is closed from ground through the stop bar 256, upper contact 251, the autostop contacts and the segment 282 of the transmitting clock TC. When the proper clock time occurs, a circuit is established from segment 282 through the coil of entry relay 22l whereupon relay 22! becomes energized and is locked up as the brush 230 of the clock reaches segment 283, the locking circuit including the.

right hand armature and front contact of relay 22l. During the time that the brush 289 is in engagement with segments 282 or 283 of the transmitting clock TC, battery is applied from a local brush of the transmitting distributor TD through segment 265 or segment 261 of the local ring 263 whereupon a circuit is closed from one of said segments through the left hand armature and front contact of relay 22I, the winding of entry and exit magnet 291, the upper winding of transposing polar relay 226 and the windings of relays 232 to ground. The magnet 291, the first five relays of relay bank 2H) and relay 226 become energized. The first relay of relay bank 210 throws its armatures 2H and 2H to the right, the second, third, fourth and fifth relays of relay bank 2 I throw or retain their armatures to the left and the two armatures of transposing relay 226 engage their right hand contacts. The

energizing of entry and exit magnet 291 lowers the horizontal roller r pivotally carried on the end of the operating arm 28l over the swordshaped projection on the stop bar 256 for the channel desiring to cut in, depressing said stop bar to its lowermost or operating position. When the local brush passes oil from the segment 266 or 261 of local ring 263, the actuating bar 28! is restored to normal, the roller r now being in such of the arm 28l, the stop bar will be raised to the position shown in full lines in Fig. 4.

In response to the operation of the relays of relay bank 2H] and relay 226 as described, positive or spacing potential is applied to the first, third, fourth and fifth segments of the transmitting ring 265 of the transmitting distributor TD and negative or marking potential is applied 0n the second segment of said ring. In due course the sending brushes of the distributor will thus transmit the line feed character (secondpulse only marking) from channel A. It

will also be noted thatthe manufacture of an .entry signal by diversion of the sixth pulse through the left hand contacts of relay 22| to the relays of relay bank 2H1 does not complete the baffle circuit through the armatures 2| l to 2l5 of said relay bank since this circuit is open at the armature 2H. Thus the baffle circuit will 4 only be closed when the line feed character is sent from one of the transmitting channels at the time channel A of the multiplex distributor 'I'D is operative.

Shortly after the mixer arm 254 is next released by the raising of the governor stop bar 210, it will engage the depressed stop bar 256 for the entered channel represented by transmitter 235. Then a connection is made between the local brush at the transmitting distributor 'TD and segments 266 or 261 of local ring 263 whereupon a circuit is closed through the left hand armature and back contact of relay 22I, the lower winding of transposing relay 226 and the magnet 210 of the transmitting mixer TM.

The mixer arm 254 is depressed for release from the stop bar 256 and momentarily engages the inner end of the contact arm 248 whereupon the normally open contacts C connecting the transmitter tongues of the transmitter 235 to relay bank 2H1 are momentarily closed. The setting of the tongues of the transmitter 235 corresponds to the character to be transmitted and the code combination is directly transferred through the above described circuit including contacts C and the armatures of relays 225 to the relays of relay bank 2I0. In due course the sending brush engaging the transmitting segments of the transmitting ring 265 will transmit the character over the lane of trafiic. If desired, the transmitter "may be constructed to send more than one character as in the modification shown in Figs. 1-3.

At the expiration of the sixth pulse operating the magnet 210 of the transmitting mixer, the mixer arm 254 rises and rotates under the force of the driving clutch (not shown) to its next stopping point which is the governor stop bar 210 as it is assumed that no other channel is cut in at this time. As explained above, the mixer I arm 254 is held at this point until the governor stop bar 256 that upon the subsequent actuation timer completes a circuit of the operating magnet 210 of the governor, whereupon the mixer arm 254 is again released to transmit another character from the transmitter 235 in the same manner as described above. The transmission of each character from the transmitter 235 is effected in part by the oscillating movement of the contact arm 248 of the transmitting mixer and in accordance with the present embodiment .of the invention, this periodic movement of the contact arm 248 is utilized to actuate a counter 242 to count the number of characters transmitted for metering purposes.

If in the course of transmission of message trafiic a line feed character having only the second pulse marking goes to the lower half of the relay bank 2H3, the character is transmitted without change from the channel Bof the multiplex distributor TD. However, if the transfer relay 225 is energized and'hthereby connects'the upper half of the relay bank 210 to the operating channel when the line feed character is transmitted, the baffle circuit including armatures 2| l, 213, 284 and 2l5 of the upper half of relay bank 288 is closed, thereby closing a circuit from positive battery through the Winding of relay 221 the armatures of the relay bank 210, the lower or resetting coil of relay 226'and the winding of magnet 213 of the transmitting mixer to ground.

' Magnet 210 is energized and holds the mixer arm 254 depressed so that'the line feed character will be again applied to the relay bank 2H3, in this case on the lower half'of said relay bank. Closure of the above described circuit resets revlay '226and energizes relay 221 whereupon the second segment of the transmitting ring 265 of the transmitting distributor is disconnected vfrom negative or marking battery and connected to positive or spacing potential. Thus, attempting to send the entry signal on A channel directly from the transmitter is prevented by the substitution of'a blank signal for the entry signal on A channel. However, the line feed character which is employed for entry in the specific enibodiment which has been described'may be transmitted on B channel and will also be transmitted on B channel when it is trapped and prevented from being transmitted on A channel. This arrangement has the advantage that characters ordinarily employed in trafiic may be also utilized as entry or exit signals but will not be transmittedover the channel which is restricted to the transmission of entry or exit signals,. although they are not lost being subsequently transmitted on another channel.

It will be evident that combinations other than the line feed character can be employed as described above either as functions to efiect entry'or exit, or as signaling combinationsfor any other purpose desired. Thus any character may be employedfor a special purpose if transmitted over A channel whereas if transmitted over B channel it has no significance-except as a mes-.

sage character. As described in this specification any such'combinations occurring in the reg 1 the mixer operating magnet 213. The mixer arm is then permitted to advance to the next stopping position. When the transmission of the message in transmitter 235 is completed and the left hand autostop contacts 245 are closed, the transmitter 235 might not stop at once because the exit or disconnection of ,a channel is rarely effected simultaneously with the actuation of the autostop contacts. The autostop mechanism is arranged to permit the transmission of a'few additional characters if exit does notoccur at once, as for example by providing a flexible extension 246 on Upon the closure of the left.

the autostop lever. hand contacts of the autostop, ground potential is'then applied to the segment 282 of the trans- In due course the'brush arm 28!] of 'thetransmitting clock TC engages segment 2'82 thereby operating entry relay 22! as described above and transmitting the entry and exit signal on A channel of the multiplexdistributor. The entry and exit magnet 2% of the transmittingmixer is again energized as described above and because of the position of the sword-like projection on the stop bar 256 in respect to the roller 1', the stop bar will this time be raised'to the channel-out position. Shortly after entry or exit is effected on the commutator oi the transmitting clock TO, the brush arm 2% of the-clock traverses a long dead segment at the time when the multiplex transmitting brush is passing over the transmitting segments of B channel. Thus no entry or exit as such can be bid for or efiected on B channel. 7

The stepping operation of the transmitter 235 will now be considered. The operating magnet SM of the transmitter is connected to positive through the contacts of a transmitter operating relay 24L or charge of a condenser 243 immediately after the delivery of a code-combination set up in the transmitter to the coils of relay bank 210 through 'above in connection with the system shown in Figsylto 3. If a .diiTerent type of transmitter is employed, obviously the circuits are arranged to operate in conjunction with such a transmitter;

In the system shown in Figs. 4 and 5, the transfer of a code combination from the transmitter to the relay bank 210 is effected when the mixer arm 254 is depressed and is pushing against contact arm 243. At this time the condenser 243 is discharged through the resistor 244. When the mixer operating magnet 210 releases the mixer arm 254, a spring restores the contact arm 248 and condenser 243 is charged in series with relay 24!, thus transmitting an operating pulse to the magnet SM of the transmitter 235 mitting clock TC from the mixer stop bar 256.

which may be as long or short as. desired depending upon the electrical constants of the circuit. Thus the transmitter 235 is operated,

stepped, released and prepared for sending out the succeeding character punched inthe tape. These operations require a definite time interval which, however, is independent of the operation of the mixer arm 254 and does not delay the rotation-of said arm to the stop bars of other channels. Thus the cyclic operation of the operating mag-net 210 of the mixer can be speeded up as it is .only necessary for the mixer arm to give a momentary operation of contacts C if sensitiverelays are employed in the relay bank 2l0. It is understood'that the mixer arm 254 must be ca- Each transmitter or channel of the expanding 1 channel system has a position on the mixer and the clock similar to that described'in connection with the transmitter 235' and each of the channels is cut in and out in the same manner as de- B' of the multiplexby the cyclic operation'of This relay MI is closed by the kick transfer relay 225 which is energized and deenergized in properly timed relation to the travel of the transmitting brushes of the transmitting distributor by the segment 228 on the local ring 230 of said distributor.

Referring to Fig. 5, when an entry signal is received on A channel of the receiving ring 309 of the receiving distributor RD, it is set up in the first five relays of relay bank 3l0 at the second station. Assuming that the entry signal is the line feed character, the armatures of the first, third, fourth and fifth relays of relay bank 3"] are thrown to spacing and the armatures of the second relay of said bank are thrown to marking. Thereupon the baflle circuit is closed through the left hand armatures of said relays and when the local brush of the local ring 3 engages segment 3l3 of said ring, a circuit is closed through the said segment and the left hand armatures of the first five relays of relay bank 3) for energizing the entry and exit magnet 39'! of the receiving mixer RM. The energization of the magnet 39'! operates the stop bar 356 of the receiving device corresponding to the transmitter which has been entered at the first station. When the receiving brush of the receiving distributor RD engages the receiving segments of channel B, the character being transmitted will be set up in the lower half of relay bank 3) and transfer relay 32I being deenergized, this character will be transferred from the contacts of said relays of relay bank 310 to the conductors 322 which are multipled to the receiving devices.

As pointed out above, the mixer arm 254 at the transmitting station missed a step while an entry pulse was being transmitted on A channel. As shown in Fig. 5, the receiving mixer arm 354 likewise misses a step when an entry pulse is received on A channel and entry is being effected. by magnet 39'! since the normal operating circuit of magnet 310 which includes the marking contacts of either the first, third, fourth or fifth relays of relay bank 3!!! and the segment 3|3 of the local ring 3 of the receiving distributor is open when the entry signal is received on A channel, but is closed for all other code combinations on this channel except the blank or all-spacing combination.

As has been described, false entry signals sent from a transmitter through A channel were converted into blanks and held up for transmission on B channel as although they were not intended for entry signals, they might be transmitted for some other purpose. The blank code combination set up on the upper half of the relays of relay bank 340 likewise holds the circuit of the mixer magnet 31!! open. But when the entry signal is repeated upon B channel, then the mixer operating magnet 31!] is energized directly from segment 3M of the local ring 3| I of the receiving distributor. On the other hand, it will be apparent that the reception of a blank or allspacing code combination upon the upper half of the relay bank 3H! will not efiect energization of the entry and exit magnet 391. Entry signals, blanks and all other code combinations received on B channel of the receiving distributor RD are stored in the lower half of the receiving bank 310 and transferred to the receiving devices or printers through the armatures of transfer relay 32! and the contacts 341 of the respective channels of the receiving mixer RM.

The mixer arm 354 of the receiving mixer comes to rest against the stop bar 356, 356a of any channel which is cut in. The mixer arm is rotated through a clutch as in the transmitting and receiving mixers shown in Figs. 2 and 3.

The mixer arm. remains in engagement with one of the stop bars until it is depressed by the magnet 316 to escape the bar whereupon the mixer arm engages the pivoted contact arm 348 and momentarily closes through contacts 341 the circuits of the selecting magnets 346 and operating magnet 348 of the receiving storing device or printer. In this case an ordinary five magnet multiplex printer or tape reperforator may be employed. At the termination of the operating pulse for the operating magnet 310 of the receiving mixer,.the mixer arm 354 rises, the contact arm 348 is restored to normal by a spring and the printer connections to the relay bank m are broken at the contacts 341.

On short lines where the possibility of mutilated line signals is very small, it is uneconomical to provide mechanisms to reduce the possibility of false entry or exit or' to facilitate the correction of false entry or exit. On long lines which are subject to interference it may happen that traffic characters transmitted over A channel may be modified by induction or in some other way to such an extent that occasionally one of such characters is transformed into an entry or exit code combination. Any entry or exit signals arriving as such on A channel will operate the stop bar of the receiving mixer to its alternate position, the particular stop bar depending upon the position of the clock mechanism at the time of arrival of such false entry or exit signal. It will be evident that the possibility exists of accidentally cutting in or out a receiving channel when the corresponding transmitting channel is not cut in or out, as a result of interference or other line trouble.

In order to aid in the correction of trouble from this source without a material change in the circuits shown in Figs. 4 and 5, a stop bar such as that illustrated in Fig- 6 may be employed. This stop bar 384 is mounted in the transmitting and receiving mixers in place of the stop bars 256 and 356 and takes the place of two of the ordinary stop bars. Two channels of the clock are used for each stop bar constructed along these lines. If an expanding channel wishes to enter when the sending clock brushes are in the' one-position, entry pulses are transmitted but may only confirm the out, inoperative position of the special stop bar. When the sending clock brush moves to the next group of segments another entry pulse is transmitted which efiects Similarly, if the armature of the entry andexit magnet attempted to operate through the projection 386 in an upward direction a stop bar which was already raised, the motion would be ineffective and would merely confirm the fact that the channel was cut out. The twoladjacent segments of the commutator of the transmitting clock corresponding to the double stop bar 384 would bestrapped together so that in effect the commutator segmentslof the transmitting clock:

I woulduse twice the space of an ordinary chan-.

nel. Obviously, it would not. be necessary to arrange all of the stop barsof the transmitting 3 and receiving mixers of the same type, for example of the type shown in Fig. 6, as some of thestop bars might be of this type and others of the type shown in Figs. 4 andl5, the special stop bars being employed on the more important channels, for example signal channels.

Another arrangement for effecting thesame 1 purpose as the stop bar 384 of, Fig. 6 but without I employing stop bars of special construction in- 1 volves' means for swinging the roller rv outward 1 for one revolution of the actuating arm 38I and inward for the next revolution.. This would make it impossible to enter a channel during the first revolution or exit a channel during the sec- 1 ond revolution. A magnet maybe arranged to swing the arm to which the roller r is attached 1 or the roller arm may be extended through a 1 guide plate 381, as shown in Fig. '7, having the inner and outer slots or tracks 388 arranged to swing the roller to the: entry and exit positions 1 above the stop bars during alternate revolutions.

The systems embodying: the invention which have been described above have outstanding adsystem to the problems encountered in transvantages both from the standpoint of simplicity 1 of the electrical circuits and control apparatus and also with respect. to the adaptability of the mission of telegraphic messages. The system 1 provides for handling different classes of traffic j in a simple and effective manner and for utilizing the full capacity of a lane of trafiic even though a comparatively small number of channels are in operation. The improved methods of effecting entry and exit embody advantages: which will be 1 obvious to those skilled inthe art. Furthermore 3 the lane of trafiic may comprise two or more wires, channels orcarriers.

While several embodiments of I the invention 3 have been described in order to explain the un-. derlying .principles thereof,.other modifications will occur to those skilled in the art and may be i made without departing from the scope of. the invention as set forth in the appendedclaims.

I claim: 1. A telegraph system comprising a. lane of means for concurrently -moving corresponding members of both mixers as each channel is cut in or. out. I

3.:A.telegraph system comprising aplurality of transmitting and receiving devices and means to render predetermined ones of said devices operative onetransmitting device and one receiving deviceat a time'and to'vary the number of operative devices, said meansincluding movable latch members which in one position initiate the operation of the associated device and a movable arm adapted to engage said latch members. 1

4'. A telegraph system comprising a plurality of transmitting and receiving devices, means to render predetermined ones of said devices operative one after another, said means comprising a rotatable mixer arm and stop or latch members movable into and out of'the path of said arm, means including saidarm for actuating said members to one position and'means including a clock arm for actuating said members to the it other position;

5. In control apparatus nel system, a mixer comprising a rotatable arm adapted to engage stop or latchmembers corresponding to operating channels and means for axially moving said arm'ito disengage the same irom said members. v

6. In control apparatus for an expanding channel system, a mixer comprising a rotatable arm adapted to engage stop or latch members corresponding to operating channels,'a resetting lug for-said members on said arm and means for actuating said lug from its normal position to a position where the movement of said arm will reset one of the stop or latch members.

2. A telegraph system comprising a lane of 1 traflic, communication channels including a plurality of transmitting devices associated with one end of said lane and a plurality of receiving devices associated with the other end of said lane, i means for variably associating the transmitting j and receiving devices with-said lane and means i for dividing the lanetime between the operative transmitting and receiving devices, said first mentioned means including mixers at each end of j the lane of trafiic, each mixer comprising a plurality of movable members, one for each communication channel, each of said members havj ing two operative positions corresponding: to channel in andfchannel out .respectively,.and

'7. A telegraph system comprising a lane of trafiic, expanding channels associated with said lane of trafiic, means for controlling the order of transmission of signals from these channels, including stop bars with in and"out positions, a rotatingmember whose movement is impeded when said stop bars are in the in position and means for rendering the corresponding trans-" mitting device operable when the movement of the rotating arm is so impeded.

8. A telegraph system comprising a lane of traffic, expanding channel's'associated with said lane of traffic, means for controllingthe order of transmission of signals from these channels, including stop bars with in and"out? positions, arotating member whose movement'is stopped when said bars arein the"in position, a switching assembly and means for effecting a relative movement between the rotating arm and the stop bars to operate said switching assembly;

9. A telegraph system comprising a lane of traific, expanding channels associated with said lane of trafiic, means for controlling the order of transmission of signals from thesechannels, including stop bars with in and out positions,

a rotating memberwhose movement is stopped when said bars are in the in position, a'switching assembly, means for efiecting a relative movement between the rotating armand the stop bars to operate said switching assembly, and means for varyingthe number and duration of said switching assembly operations.

10. An expanding channel system wherein at least a part of the transmitting time of an idle channel is utilized by. a busy channel, means for transmitting an entry signal consisting of a multiple-character code combination concurrently .with intelligencefsignalson. busy channels and for an expanding chan means responsive to such signal for temporarily entering a channel.

11. An expanding channel system wherein at least a part of the transmitting time of an idle channel is utilized by a busy channel, means for transmitting an exit signal consisting of a multiple-character code combination concurrently with intelligence signals on busy channels and means responsive to such signal for disconnecting a channel.

12. An expanding channel system as set forth in claim wherein the component parts of the entry signal are sent over different multiplex channels.

13. A telegraph system comprising a plurality of transmitting and receiving devices and means to render predetermined ones of said devices operative in sequence and to vary the number of operative devices, said means including movable latch members individual to each of the transmitting channels and having two operative posi-: tions and further including an actuating bar arranged to operateany of said latch members to either of its respective positions.

14.. A telegraph system comprising a plurality of transmitting and receiving devices and means to render predetermined ones of said devices operative in sequence and to vary the number of operative devices, said means including movable latch members having two laterally displaced projections, said projections having oppositely disposed cam surfaces, and an operating member adapted to engage either of the projections of any of said latch members to operate the latch member from one position to another.

15. An expanding channel system comprising a lane of traffic, a plurality of subchannels sharing said lane of trafiic and means for connecting selected ones of said subchannels to a lane of traffic while omitting other channels in a manner to utilize at least a part of the transmitting time of an idle channel, said means being arranged to connect invariably the same number of operating channels to the lane of trafiic.

16. An expanding channel system wherein at leasta part of the transmitting time of an idle channel is utilized by another channel comprising a lane of trafiic, a plurality of channels adapted to operate over said lane of traflic, said channels including sending devices provided with contacts, control means for transmitting an entry signal over said lane of traffic and means for trapping code combinations corresponding to said entry signal which are originated at the contacts of the sending devices to prevent the transmission of such code combinations except by said control means.

17. An expanding channel system wherein at least a part of the transmitting time of an idle channel is utilized by another channel comprising a lane of trafiic, a plurality of channels adapted to operate over said lane of traflic, said channels including transmitters and receiving devices, means for transmitting an entry signal code combination over said lane of trafiic to enter a receiving device and means for converting a corresponding code combination originating at the contacts of one of the transmitters to a difierent code combination to avoid the transmission of a false entry signal.

18. An expanding channel system wherein at least a part of the transmitting time of an idle channel is utilized by another channel comprising a lane of traflic, a plurality of transmitters adapted to operate over said lane of traffic, control apparatus for transmitting a code combination over said lane of traflic, a device responsive to said code combination when it originates at.

said control apparatus and means whereby said device is not responsive to the transmission of said code combination from one of said transmitters.

19. An expanding channel system wherein ,at least a part of the transmitting time of an idle channel is utilized by another channel comprising a lane of traffic consisting of a plurality of multiplex channels, a plurality of transmitters adapted to operate over said lane of trafiic, control apparatus for transmitting a code combination over one of said channels and means for preventing the transmission of said code combination from any of said transmitters.

20. An expanding channel system wherein at least a part of the transmitting time of an idle channel is utilized by another channel comprising a lane of traffic, a plurality of receiving devices adapted to be operated over said lane of traffic, means for transmitting an exit code combination over said lane of traflic to disconnect one of said receiving devices from the system and other means for transmitting code combinations over said lane of traific, said other means being inoperative to transmit said exit code combination. 1

21. An expanding channel system wherein at least a part of the transmitting time of an idle channel is utilized by another channel comprising a lane of traflic consisting of a plurality of multiplex channels, means for transmitting entry signals over one of said channels and means for deferring the transmission of code combinations from transmitting channels which would normally be transmitted over said one of said multiplex channels.

22. An expanding channel system wherein at least a part of the transmitting time of an idle channel is utilized'by another channel comprising a lane of traffic, a plurality of channels adapted to operate over said lane of traffic, means for transmitting an entry signal over said lane of traffic, means responsive to said signal for effecting an entry function and means for rende'ring nonfunctional certain errored signals similar in part to the entry signal.

23. An expanding channel system wherein at least a part of the transmitting time of an idle channel is utilized by another channel comprising a plurality of channels, means for entering channels in response to a transmitted signal and means for trapping said signal under predetermined conditions to prevent the entry of a channel under those conditions.

, 24. In a telegraph system comprising a transmitting channel and a signal transmitting device, signal storage means in circuit with said ,device for repeating certain character code combinations from said transmitter over said transmitting channel, and means including said signal storage means for automatically preventing 26. In an expanding channel telegraph system,

wherein substantially all of the transmitting time is utilized by a variable .number of opera-itive channels that have beenv entered on thesystem, the method of varying the number of opera-. tive channels which. comprisesallotting separate time intervals for the control of the respective channels, transmitting a signal over thesystem during'the time interval allotted toany one of channels which is .to be controlled and utilizing the signal on receiptthereof to vary'the operative relation :of the receiving end of said one channel to the system. J i 27. In an expanding channel telegraph system, wherein substantially all of the transmittingtime is utilized by a variable number of operative channels that have been entered on the system, the method of'entering a channel for operation which comprises .allottingseparate time intervals 'forthe control ofthe respective channels, pre-. paring a circuit :at the receiving station during eachof said time intervals for effecting entry of the receiving end of. the corresponding channel, transmitting a signal during the time interval allotted to a channel which is to be cut in and completing the entryzcircuit for entering the receiving end of said channel upon receipt of said signal. r 28. In an expanding channel telegraph system having a plurality of channelsand wherein sub-' stantially all of the transmitting time is utilized by a variable number of operative channels that have been entered'on thesystem, the method oi entering and disconnecting channels which com prises transmitting the same control signal come bination for entering a channel that is out and for disconnecting a channel-that is in and entering or disconnecting the channel upon the-trans mission of said signal.

29. In an expanding channel telegraph system having a plurality "of channels and wherein substantially all the transmitting .time is utilized by a variable number of operative channels that have been entered on the system, the method of entering and cutting out channels for operation which comprises transmitting'a code combination used in the regular transmission of messages entering or cutting out achannelwhen said code combination is transmitted as a switching signal and employingisaid code combination as a message code combination at other times.

30. In a. multiplextelegraph system, the meth+ d of signaling whichcomprises allotting a multiplex channelor channels to the transmission of asignaling code combination identical with an intelligence code combination which may be sent over another channel and deferringythe transing two ofiices, means for transmitting message signals between said oliices on the busychannels, one after another and means for interspersing signaling or operating impulses with said message signals.

32. In an expanding channel system-wherein at least a part-of the transmitting time of anidle channel is utilized by another channel, a .plurality of transmitting channels for sending message or character-code signals, one or more sigone ofiice, a plurality of receiving channels at the secondv office and means controlledfrom. said second office for stopping transmission from all of said transmitting channels at the other ofilce;

.34. In combination, signal circuits, a signal storing device, a reciprocablemember and means including said member for extending the signal circuits and stepping said signal storing device in a single forward and back movement ofsaid member.

35. In combination, signal circuits, a receiving device responsive to signals, a reciprocable memher and means including said member for extending the signal circuits and operating said receiving device in a single forward and back.

movement of said member.

- 36. An expanding channel telegraph system comprising a plurality of channels, a lane of traflic shared by the operating channels of said system, means for causing channels having message traflic to take their share of the laneoi trafiic until and only'until their traific 'has'been transmitted, means associated with each channel for generating current impulses varying in number as the messages on the corresponding channel vary in length and varying-in frequency as the number of channels operating over the lane of trafiic varies, and means actuatedby said impulses for metering the traffic on the corre-- sponding channel. 1 37. An expanding channel telegraph system comprising a plurality of channels, a lane .of trafiic shared by the operating channels of said system,means for causing channels having message traffic to take theirshare of the lane :of traffic until and onlyuntil their traflic .has been transmitted, means associated with each channel for generating current impulses and means actuated by said impulses for operating the .trans'-. mitterofthe corresponding channel and for metering-the traffic thereon. 38. An expanding channel telegraph syste comprisingia lane of traflic, a pluralityof channels of communicatiommeans for causing a variable number of said channels to share thelane of traflic in turn at a frequency of transmission" dependent upon the number of operative channels, means associated with each channel m transmitting over said lane of traffic a group of signaling impulses on each transmission turn of tive ones of said predetermined channels under control of said meteringimpulses.

.39. An expanding channel system comprising a plurality of channels, a'lane of traflic, means including a mixer for enabling the operative 41. An expanding channel system comprising a lane of traflic, a plurality of subchannels each including transmitting and receiving apparatus, means for dividing the transmitting time of said lane of traflic between operative ones of said subchannels and for cutting out subchannels when they have no signals to transmit and means for simultaneously cutting out all of the busy subchannels irrespective of the busy condition 10 thereof.

PHILO HOLCOMIB. JR.

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