US2364771A - Telephone signaling system - Google Patents

Description

Dec. 12, 1944-. M. BASCOM 2,364,771"

' TE PHONE SIGNALING SYSTEM Filed 152137.28, 1942. 3'Sheets-Sheet 1 H M BASCOM INVENT FRANCIS A. HU BARD ATTORNEY Dec.'12,1 944. Hqm. BASCOM HAL 2,364,771

R TELEPHONE SIGNALING SYSTEM 7 Y Filgd Na -128, 1942 s Sheets-Sheet 2 FIG. 3

FIG. 4 1 56 4/ 47 3040 o -I 59 I 36 52 25 Q 49 la 77 INVENTORSI H. M'BASCOM f, FRANCIS AHUBBARD r 1 ATTORNEY 12, 1944. H BASCQM f 2,364,771

TELEPHONE SIGNALING SYSTEM Filed May 28, 1942 s Sheets-Sheet a FIG, /0

I T M BASCOM INVAN ZfRANCIS A. HUBBARD v ArroR/"vEr Patented Dec. 12,

- TELEPHONE sIcNALmG SYSTEM Henry M. Bascom, New York, N. Y., and Francis A. Hubbard, MaplewoorLN. 1., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application May as, 1942, Serial No. 444,772

15 Claims. (Cl. 177353 This invention relates to signaling-systems and particularly to telephone intercommunicating systems of the type wherein telephone connections between calling and called subscribers stations are established, under control of the calling subscriber, by means 'of a key-type sender or transmitter, which functions to effect the transsta'tion-selecting signals which are characterized by various combinations of positive and/or negative direct current impulses over the line wiresextending from the signal transmission station mission of station-selecting signals comprising various combinations of positive and/0r negative direct current impulses, and wherein the various impulse combinations are registeredat a signal receiving point by translating devices which selectively respond to the impulses which characterize the transmitted signals and controlthe operation of station-connecting relays.

Heretofore, there have been proposed telephone station-selecting systems of the type wherein connections are established, under the control of a calling subscriber, by means of a rectifier-type key-sender which functions to cause the transmission of various combinations of positive and/or negative direct current impulses over a line extending to a central point. The impulses thus transmitted serve to selectively control the operation of translating devices at the central point which function to complete the connection of the calling subscribers telephone to a particular called telephone. In order that a sufllcient number of station selections be possible to render such systems practicable it has been found necessary,

to selectively operate signal receivingequipment at a signal receiving station.

This object is attained in accordance feature 01' the invention by the provision-"or a -key-type sender ofthe rectifier type which renin transmitting certain of the station identifying impulse combinations, to utilize signal paths comprising either line conductor and ground. Ob-

viorusly, such systems require a suitable ground connection at the signal transmitting; or calling .subscribers station.

In U. s. Patent No; 2,278,410, issued April' '7.

1942', to Henry M. Bascom et al. there is disclosed an executive telephone call system in which oppositely poled rectifiers are adapted to beconnected singly or in combinations, between each line wire and ground at the subscriber's station to efiect fifteen distinct station selections. This system functions satisfactorily and serves the purpose for which it is intended in all cases where a suitable ground connection is available at the l telephone subscribers stations. Under some conditions, such a suitable ground connection at the subscribers stations is not available.

g It, isthe object of this invention to obviate the need-tor aground connection at the subscribers station'soi a telephonesystem in which telephone connections, betweencallingyand-called.subscrib-, ersfstations are established under the control of:

the calling subscriber-,3 by the transmission of";

December giiifl ders it possible for fifteen distinct station-selectins signals to be transmitted over the metallic loop which interconnects the signal transmitting and receiving stations. More specifical y, this ob- Jeet is attained by incorporating in a rectifier-type impulse transmitter, mechanism which functions to provide independent operations of the rectifierconnecting means for each of the down and upstrokes of the individual keys of the impulse transmitter. Such a structure renders it possible to connect one or more rectiflers between the two line wires twice for each complete operation of a station-selecting key. I In this manner, certain of the keys of the transmitierffunction to cause the ton of two pulses, or two groups of pulses consecutively over the metallic loop'for a single complete operation thereof.

Another feature of the invention resides in a particular form of signal receiving circuit which distinguishes betweenimpulses transmitted during the down-stroke of the keys of a key-type sender and impulsestransmitted during the upstroke of the keys.and which iimctions to register the signals thus transmitted. A further feature of the invention'resides in a signaling system in which more than one signal may be characterized in the same manner, and in which discrimination between signals having the same characterization is obtained by transmitting one'signal during one portion of a signal-trans mitting period and another signal during a dlflerent portion of the. signal-transmitting period.

Before entering into a detailed description of the circuits and apparatus disclosed in the accompanying drawings, which are illustrative. of"

h ifi of n w mul e a e r m re l umma n n a mm. sw m.

. stroke of certain other keys.

code bar functions to operate the second-men'- tioned set of contact springs during the downstroke and an up-stroke, and the code bar are actuated by the button during its down-stroke and are restored to normal when the button is" released, by means of restoring coil springs,

there being one such spring for each bar. Each of the four code bars is provided with an integral, inwardly projecting arm which carries at its extreme end a pawl. Each of the four pawls cooperates with a particular one of four ratchet wheels in such amanner as to cause the rotation of its corresponding ratchet wheel through- ,an arc of 90 degrees, either during the down-- stroke of a key, or button, or during the upstroke thereof. For example, two pawls, assigned respectively to two particular code. bars, are effective in rotating their-corresponding ratchet wheels only during the down-stroke of the key, and are ineffective to rotate the ratchet wheels duringthe up-stroke of the key. Similarly, two other of the pawls, individually assigned to the other two code bars, are effective in rotating their corresponding ratchet wheels only. during the up-stroke of a key, and are tneffective to rotate the wheels during the downstroke of the key. In this manner an number,

pending upon the number of code bars actuated by ,the key. p Two of the four ratchet wheels are fixed to one section of a composite bar comprising a cy-.

lindrical portion and aportion having a square cross section, the two portions being coupled by a coil spring so that the portion having the'flat surfaces lags slightly behind the cylindrical portion when the latter is rotated. In other-words,-

the rotational movement of the cylindrical portion is transmitted to the fiat-sided portion through the coupling spring. As each ratchet wheel is rotated, the compositebar is similarly actuated. The flat-sided section of. the bar nism'when one of the actuating buttons, or keys one to four, of the ratchet -'wheels may be operated'durlng a complete operation of a key de-- disconnected until the actuated key is restored to normal. This insures the disconnection of the telephone set from the mission of impulses. 1 t

, Reference will now be made to the acco panying drawings, in which:

Fig. 1 is a perspective view of a telephone set equipped withfifteen buttons arranged in accordance with applicants invention; Fig. 2 is a general view of the apparatus which is housed in the telephone set shown in Fig. l, andthe mechanism .controlled by the buttons located externally of the set, as shown in Fig. i;

Fig. 3 is a side view of the telephone set shown in Fig. 1 with part of the housing broken away to show details of the button-controlled or key-' controlled switching mechansim;

Fig. 4 is a fragmentary side view of the telephone set shown in Fig. 3 and illustrates the position of the switch contact controlling mechaline during the trans is operated; 1

.Figs. 5, 6, 7 and 8'are enlarged fragmentary I views of the contact controllingmechanism."

Figs. 5 and 6 illustrate the positions of the down and; up ipawls just prior to the actuation ofa 1 station-selecting button and in reality, constitute enlarged views of the contactactuating mechanism inthe normal position shown in Fig. 3. Figs. 7 and 8 correspond to Figs. 5, and 6 but show the contact operating mechanism after a station-selecting button has been depressed. In

' to register the impulses transmitted during the functions to operate contact springs which convaristors between the second composite bar of the same construction as the bar described in the preceding paragraph, and serve to actuateza second set of contact such that one particular code 1-bar functionsatn effect the operation of the first-mentioned set of contact springs during the downstroke of cer-- tain keys, and a second code bar functions to operate the same set. of springs during the upsimilarly. third stroke-of still other of the keys, and"the fourth code bar serves to efiect the actuation'ofthe same second set of contact springs during the. un-stroke of the remaining keys. The key-type transmitter is also equipped with a smaller U-shaped bar which is operated when- 7 ever any one of the code-bars is actuated. This U-shaped bar functions to open a set of normally closed contacts which control the connection 01' the subscribers telephone set to the line. Thus,

, whenever any one of'the station-selecting keys, or buttons, is actuated, the subscribers telephone varistors between .eration. I

. Referring-now to Figs. 1 to 9, inclusive, of the operation of the station-selecting buttons shown in Fig. 1. In this figure, the contact-controlling mechanism is schematically illustrated at the left of the vertical broken lines;

Fig. ll is a circuit diagram similar to Fig. 10. except that'a gas-filled tube type of receiving circuit is;shown instead ofan all-relay typ and Fig. 12/ is a table showing the various contactcombinations which are efi'ecteddor the actuation of each button, or key, and they correspond-' ingcode relays which respond toeach key opdrawings, the subscriber's telephone consists of a handset I' mounted on a cradle 2' formed inte'grallly with the housing a of the telephone set, the housing being sulpported on a base plate 4'. .On the front surface "of the housing 3 is shown the usual dialmechanism 6 and fifteen buttons i arranged in a single row I below the dial. Immediatelyin front of the row of buttons, and fixed on th housing 3 is a transparent plate It under which the designations correspondingto the individual buttons, orkeysmay-be placed. In Fig.- 2 is shown .the'general arrangement of the-apparatu housed insidethe telephone set.

This apparatus comprisesa ringer H; induction coil ii; a switching contact arrangement is controlled in the usual manner by the handset I when placed in the cradle 2', or removed there from; the dial 8; button-controlled U-bars or levers Ii; the groups of contact springs controlled tons. I

Each button consists of a cylindrical portion 26 (Figs. 3 and 4) protruding through an open ing in'the inclined front portion 2| of the hous ing 3. The button is provided with a flange 22 that abuts the inner surface of the inclined portion 2| of the housing 3; with an inner cylindrical portion 23 of larger diameter than the cylindrical portion20; and with a cylindrical portion 24 of somewhat lesser diameter than the portion 23'. A helical spring 25 is wound around the shank portions 23 and 24 of the button so that cause a corresponding combination of bars l5 to berotated about the pivot pins 30 and 32.

Also supported between the ear-like append ages 40 of the bracket 3| is a short U-shaped bar 46 which is adapted to be rotated about the pivot pin 39. This bar 46 is located under the integral projections l5 of the bars l5 and is adapted to be rotated about the pivot whenever any one of the bars-or levers I5 is actuated. This U-bar also carries an integral projection which extends inwardly from the pivot pin 36 and has fixed thereto, at its end, an insulating stud-41 which, when One nd thereof abuts the flange 22 and the other end abuts the mounting plate l8 secured to the front portion 2| f the telephone set. The shank portion 24 protrudes through an opening in the mounting plate 3 so that the button may be caused to-move axially downwardly in the opening, or aperture in the mounting plate 8 when the button is'manually depressed, and is-caused to return to normal position by therestoring ac-- tion of spring 25. The normal position of the buttonis determined by the flange 22 and the extent to which it may be depressed is determined by the shoulder formed at the'junction of the shank portions 22 and 23 and its engagement with the plate I8.

,The buttons control the operation of four levers, or code bars lv (Fig. 2) which are substantially U-shaped and arelocated at the forward end of the telephone set. Each 'bar consists of an elongated (portion extending substantially the entire width of the base plate 4'-, and a right-angle extension 5' integrally formed with the elongated portion and located at each extremity thereof. As shown in Fig. 2, these exa tensions are provided with apertures which accommodate the pins 30 and 32, the pin 30 serving the extensions IS on the left, and the pin 32 serving the extensions |-5' on the right, looking towards the front of the telephoneset. The. bars are thus mounted for rotation about the pins 36 and 32. ear-like appendages 46 of a spider-like bracket 3| which is secured to the base plate 4 by means of rivets 3|. as clearly shown in Figs. 3 and 4. The pin 32 is supported in. a; similar manner by the bracket 33 shown in Fig. 2, which is similarly secured to the base plate 4'. The'left-extensions' l5 of the two lower bars I5, when-viewed from the front. of the telephoneset, are each provided with an integral projection .which extends in-.

The pin 3llis supported between two the bar 46 is operated, engages an extension of the contact spring 49 and disengages the spring 48 from its mate spring 49. Thus, whenever any button is depressed, the normally closed contacts of springs 46-49 are opened for a purpose to be hereinafter explained.-

The bracket 3| is provided with two integral horizontal projections 56, both of which are shown in Fig. 2, and only one of which appears in Figs. 3 and 4, which support a rod or pin -5|.

This rod serves as an anchorage for one end of each of a plurality of coil springs 52 whose other ends are individually anchored to the inwardly projecting arms of the U-bars I5 and 46, such as the arms 4| and 42. These springs function to restore the U-bars |5,and 46 to normal position after the manual depression of the corresponding buttons. The bracket 33 is similarly provided with a pair'of horizontal projections 53 and 54 whic h serve to support the rod or pin 55,

which provides a means for anchoring one end of springs, similarto the springs 52, the other ends of which are secured to the inwardly projecting arms 43 and 44 of the U-bars l5. These springs also serve to restore the U-bars l5 1; normal after actuation.

At the outer extremity of the arm-4| there is pivotally mounted, at 56, a pawl 51. This p'awl may be associated with the arm 4| by means of a screw 58 as clearly shown in Fig. 9. Similarly, the. outer extremity of the arm 42 pivotally supports a pawl59. The screw 60 serves to associate the pawl 59 with the arm 42. The pawl 51 is provided at its lower end with a dog 6| pivotally supported on the pawl at 51. The pawl 5.9

The pawl 51 may be characterized as a "down I pawl and the pawl-59 as an -up pawl, since these pawls perform their respective functions wardly frompivot pin 36, the functions of which be set forth in greater detail hereinafter.

These projections are identified by the numerals 4| and 42. Similarly, the rightor lower extensions l5 (Fig. 2) of the two upiper bars|5 are .each provided with an integral projection which extends inwardly from th pivot pin 32., the func. tions of which will be described hereinafter.

These extensions are indicated by the numerals 43 and 44. (I

The elongated portions of the U -bars |5are provided with projections or fingers, such as 36.

31, and others located in various positions throughout the length of the bars. Some of these.

projections are bent inwardly and others project button is depressedfa crtain numberfdfthe prow ss- Such as a 1,; p been??? a during the down and u strokes, respectively, of certain of the buttons as will be fully described hereinafter. The bracket 3| is provided with two vertically. spaced projections 64 which support a rod 65. The rod 65, viewing particularly Fig. 9, consists of a cylindrical portion to which the numeral 65 is applied, and a portion 66 having a square cross section. The portion 65 is coupled to the portion 66 by means of a coil spring 61, the purpose of which is to introduce a time lag between the rotational movement of the portion 65' and the portion 66. The rod is capable of rotational movement under the action of the pawls 51 and 59 as will appearprsently. 1

Fixed to the rod or shaft65 near its left end, viewing Fig. 9, there are two ratchet wheels 68 and 69, each of which is provided with four teeth f displaced ab ut thfep iiatfeo-d re inttervals'. As shown in Figs. 5 and-;6,'*which-illus- I *trate the pawlfand ratchet arrangements iii'their normaljpositions,the dogi6| or, pawl 51 lien 16- With respect to the ratchet teeth that, as

4 the pawl is moved upwardly under the action oi a button, the edge of the dog engages the tooth l 'and ..causes the ratchet wheel. 88 to rotate through 90 degrees in a clockwise direction. The

position of the, dog BI and ratchet tooth it after the down-stroke of a. button has been completed 3 aces-r21 is illustrated by Fig. 7. The pawl 59', as hereinbefore described, has pivotally associated there- .with the dog St; the pivotal association being efie'cted by the pin 62. The pin 62 also serves to support a pair of substantially triangularly shaped member H which are integrally joined' atone end'to effect, substantially, an enclosure for the ratchet Wheel 68. The integral union is ciation of the spring-supporting enclosure eiiected by members II and 12 and the V-shaped dog consisting of the projections 6i and 14, with the pawl 51, which association is effected by the pin 62, whenever the pawl is raised in consequence of the depression of a button, the enclo sure is rotated on the rod 65 and the dog element 6! is.-similarly moved to cause the ratchet Wheel 68 to be rotated. The position of the spring 18, as well as that of the dog elements 6i and I4 after the operation'of a button is illustrated in Fig. 7. v

Referring now particu'larlyto Figs. 6 and 8, the

pawl'59 which heretofore has been referred to I the enclosure portions 15 is associated with the pawl 59 by means of the pin 83, assumes the position shown in Fig. 6. When a button is de-' pressed so as to raise the pawl 59, the enclosure, comprising elements 15 and I6 and spring TI, to-

gether with the dog- 62 are moved so as to assume the positions shown in Fig. 8. It will be noted that the edge of the dog 62 has moved to such a position-relative to the ratchet wheel 69, as to be in readiness to engage the tooth 80 when the actuating button is released, and the U-bar 5,

with which the pawl 59 is associated returns to,

normal under the action of its restoring spring 52. Thus,.during the down-stroke of the button. the dog 62 rides over the curved periphery of tooth 80 of ratchet wheel 69 without efl'ecting, any

movement of theratche't wheel, and during the up-stroke orthe button, thedog 62 causes the ro-' tation of the ratchet wheel 69 through 90 degrees. From the description thus far advanced, it is apparent that whenever a button or key is depressed so as to operate a U-bar I with which the down" pawl 51 is associated, the ratchet wheel 68 is rotated through an arc of 90 degrees.

Similarly, when a key is depressed so as to op-v erat'e a .U-bar with which thefupf pawl 59 is associated, the ratchet wheel 69 remains stationary, and during the return stroke otthe button,

the ratchet wheel 69. is rotated through an. arc

.- of 90'degree's. It is well at this time to indicate that though the pawl 51 functions during the down-stroke-of a key "orbutton to rotate the ratchet wheel 68 through an arc of 90 degrees, the dog 6! does not cause the actuation of the ratchet wheel during. the, lip-stroke of the key; though the pawl 61 is moved downwardly to its normal position at that time. That this. is the case is apparent from an'examination of Fig. "l

which shows the dog 6| in the position it occupies just prior to the release of the actuated button.

,The mechanism just described, which functions when the U-bars IS, with which the projections 4| and 42 are associated are operated, is dupli cated at the bottom of Fig. 2, (or at'theright oi the handset interior, Fig. 2) so that the same ratchet wheel operations are eflected by the U- bars IS with which the integral extenions 43 and '44 are associated. Thus there are two U-bars I! which are efiective in rotating a ratchet wheel during the down-stroke of certain buttons and two which: are eflective in rotating a ratchet tioned portionof the rod!!! which is controlled through the medium of the U-bar extension 43' and 44. These lsimilarly mounted on the bracket 33 shown at,

' the various mechanical operations which follow" wheel during the up-stroke of certain other buttons. More specifically, the U-bars I5 with which the integral extensions 4| and 43 .are associated vfunction to operate a ratchet whe'eLduring the down-stroke of a button, and the U-bars [5 with which the integral extensions 42 and 44 are associated' function to effect the rotation of a ratchet wheel during the up-stroke of a button.

As shown to the right of Fig. 9, the section 66 of the ratchet supporting bar is operatively associated with a contact spring 82, which spring 82 is adapted to -be moved into engagement with the contact spring. 83'. As the bar section 68 m tates under the action or the pawls B'Iand 59 it serves as a cam to move the spring 82 into engagement with the spring 83 in such a manner that the contact spring 82 and are in engageinent during a portion of the rotational movement-of bar section 66 and are disengaged before the bar section completes its -degree rotation.

It is understood that a similar set of contact springs is' located at'the bottom of Fig. 2 to be actuated in a similar manner by the square-seccontact springs are indicated by the numeral 9i.

.As clearly disclosed in Fig. 3, the bracket 3| serves as a support for the spring. pile-up 92 which includes the springs 48, 49, 82 and 83. The spring pile-up 93 which includes the spring 9| is the bottom of Fig. 2.

In order to more fully explain the operation of the key, or button-type sender described above,

the operation of. several of the keys will nowbe described. It will be assumed that the button a to the extreme left-of Fig. 1 is depressed and released and that this button causes the operation of only the outermost U-bar l5 (Fig. 4) by virtue of the engagement of the bottom of the shank portion 24 with a single projection 31 associated with the U-bar. The U-bar i5 assumes the position illustrated in Fig. 4 and by virtue oi the engagement of the integral projection ll thereof with the smaller U -bar 46, the insulating stud 41 engages the contact spring 48 and disengages it from the spring-49. The purpose of these contactsprings will appear from a description of the circuits of Figs. 10 and 11 to be made hereinafter. At the same time, the integral extension 4|, of the actuated U-bar I5 is moved upwardly by virtue of its pivot support 80. In mov-- ing upwardlmthe arr'n 4| pulls the pawl l1. up-

,closed.

Should a key or button be actuated which and/or 8|, respectively.

wardlycausingthe dog 8| associated. therewith causes the latter to rotate through the same arc. 1

The rotational movement of the bar 88 is trans- In Fig. ortne disclosure the key-sender located at the transmitting station, which may 1 be a telephone subscriber's station, -is indicated mitted to. the square-sectioned portion' '88 through the coupling effectedby spring 81 so that the portion 88 rotates 90 degrees, its rotational movement lagging slightly behind that of the bar 85. In rotating through an arc of 98 degrees, the square-sectioned portion 68 causes contact spring 82 to approach, engage, and disengage the contact spring 88 for a purpose to be described hereinafter. Thus, during a portion of the down-stroke of the button, the contact springs 82 and 88 are closed'and before the button reaches the lower limit of its down-stroke these contacts are opened. This sequence of contactoperations is produced by the square periphery of the rod section 88.

. When the button is released, it is restored-to normal under the action of its associated spring 28, and spring 52 associated with the actuated U- bar functions to restore the actuated U-bars Thus, the U-bar extension movesdownwardly and during the downward movement thereof the ele.-- ment 8I moves back over the surface of the ratchet wheel 68 to assume a position under the next succeeding tooth 85 in preparation. for a schematically at K. In this' showing, the controlling contacts are identified by the letters A and B. The contacts A correspond ;to the contacts 82-88 in Figs. 3 and 4, and the contacts B are intended to correspond to the contacts indicated at 8| in Fig. 2. Since each of these contacts may be operated during the up-stroke or the down-stroke of a. key, applicants have illustrated, in the schematic illustration, 'two' other pairs of contacts 'D ,,D= and U and U,- the D designation indicating that the contacts D and D engage with contacts A and B, respectively,

during the down-stroke, and the U designation g indicating that the contacts U and U engage with contacts A and B, respectively, during the subsequent key operation. During this return movement, the ratchet wheel 88 remains stationary. Thus, for a complete operation of the key,

or button' a, which includes its down-stroke and its up-stroke,'the contact spri gs 82 and 88 are actuated-once. Obviously, when the actuated U- bar returns to normal, the auxiliary U-bar 88 re- B, respectively.

depressed,.it is assumed, in accordance with the schematic showing of the key-senderK, that the contacts D and/or D approach and engage contacts A and/or B,- respectively, while during the up-stroke of a key the contacts U and/or U approach'and engage the contacts A and/or Before entering into a detailed description of the operation of the system shown in Fig. 10, it may be welLto mention the particular sequence of contact operations which is followed for a compiete operation of a key, that is, for a combined down-stroke and up-stroke thereof. Normally,

' the circuit is as illustrated. The rectiflers V and V= are open-circuited and the line loop is open at the contacts of the "subscriber's telephone set.

' When the telephone set-is'removed from its supstores under the action of its individual coil spring and the contact itself opposite the tooth 88 thereof, During thisdownwardmovement of the key orbutton, .the ratchet wheel 88 does not rotate and the contact springs 82 and 88reinainiunactuated. The cori-v tact springs 48 and 88, however, are .diseng'agedi When the button is released, a spring 82 restores the actuated U-bar' to normal, that is, the

springs 88 and 88 are again.

arm 82, is moved' downwardly causing the dog 82.

to engage the tooth 88 of the ratchet wheel 88 and move the wheel through an arc of degrees. The bar section-88, accordingly, is-rotated during the up-stroke of the key or button to close the contact springs 82 and 88.

By virtue ofthe fact that certain of thebuttons -or keys engage two or more of the U-bar pro- Jections 88, 81, itis apparent that more than one U-bar, and up to four, may be actuated in response tothe operation of a button. Under these circumstances the U-bars associated with the integral proj ctions I and/or 48 function during the down-stroke of the keys flbpperatethe contact springs 82 88, and/or 8|, respectively,

while on the up-strqke of the keys the U-bars associated'with "the integral projections l2-and/0r 88 function. to operate the contact springs 8288 The operation of a. signaling system involving ings will. now be described.

port, the line loop is closed through'the subscribers substation set by way 'of the contact C.

Contact G corresponds to the contacts 48-18 of,

Figs. 3 and 4. ,As soon as a key starts its downstroke, thecontact C is opened as described hereinbefore'and this openingis, or may be, immedi-' atelyfollowed by the closure of the line loop through either one or both rectiflers V and W and resistance R. The opening of the contact C disconnects the telephone subset from theline L. Just as a key reaches the end of its down-stroke,

theline 'loop is completely opened, that is,. contact cremains open and theactuated contact A or B reopens During the up-stroke of a key,

the line loop is, or may be, again closed throughrectifiers V or V, singly or in combination, and

resistance R. 1 As the key reaches its normal position, the-line: loop'is -closed through the subscribers subset owing'to the closure of contact G,;it being understood that the key-sender is so designed that contact C opens upon theactuation of any key and remains openuntil the key resumes its normal unoperated position. Thus the subscriber's set is disconnected from the line lpulsing. Located at the receiving station, orcentral omce, is an ail-relay receiving circuit which .is,

' supplied with power from the alternating current source'll8 by way of the transformer III.' The designated I88 and 188.

receiving equipment comprisesjfour code relays,

designated L1, 8 and 8, and two control relays,

nected in pairs across ,single oppositely poled rectiiiers. I with the pair of relays co'ns I88 and I88 are connected in a-full-waverectifler circuit comprising. the'rectiflers Ill-,1", H8,

and Ill. The circuit arrankementissuch that The code relays are con- Rectifiers I81 and I88 are associatedg of relays I and 2-, and rectifl ers H2 and H8 9. associated with the pair of relays l and 8. The control relays irelays'l andregister the impulses transmitted during the down-stroke of the keys of the key.

sender, while relays-2 and 0 register the impulses transmitted during the up-stroke of the keys. Furthermore, relays I and 2 register the positive direct current impulses, while relays 4 and8' register the negative impulses.

Control relay I05 is marginal-and will operate 0 when the line loop. is closedithrough the subscribers subset S, that is, when the subscriber removes thetelephone set from its cradle "support, but will not hold operated when resistance R is connected to the line. The resistance R is connected in series with the recttfiers V and W relays I, 2, 0 and 8 to receiyethe transmitted signals by removing a short from therectifiers m and I I2. This short is effected at the front contact and inner armature of relay I05. At its outer armature and back contact, relay I05 proyides locking battery for the impulse receiving v relays. 1

Control relay I03 is made slightly slow to opindicated, relay I05'operates under this condition. The circuit in which relay I05 operates may be traced. as: follows: during the first half-cycle of closed contacts 0, through the subscribers suberate and to release. It -is more sensitive than relay I00 and will hold operated through resist- .ance R, but-will release when the loop is completely openedv at the end of the down-stroke of .the individual keys. Relay I00 serves to transfer current from the source 0, the-upper terminal. of the secondary winding of transformer I I I may be assumed to be positive and the lower terminal negative, so that the circuit extends from the j upperterminal of thesecondary of transformer II I, through rectifier II5, winding of relay I05, rectifier, H0, over the tip conductor of line 'L,

set 8, ring conductor of line L, rectifier I01, back contact andjleft armature of relay I03, operating winding of relay 2, rectifier I I2 to the lower terminal of the secondary winding of transformer III. on the next half-cycle, the circuit may be traced from the lower terminal of the secondary winding of transformer III, rectifier II3, oper-' ating winding of" relay-0, right armature and back contact of relay I03, rectifier. I09, ring conductor of line L, through the subscriber's set S;

closed contacts C, tip conductor of line L, recti- I fier H4, winding of relay I05, rectifier II' to the upper terminal of the; secondary winding of transformer III. Relay-I05, therefore, operates on the rectified altemating' current'traversin'gthe circuits just traced. Relay. I03 being connected in parallel with relay I05 also operates in these circuits a short intervalafter relay I05 operates. The operating 'windings of relays 2 and 0 being included, each in one'of the circuits just traced, these relays may operate. but will release 4 immediately .upon the "operation; of .relay I05.

the registrationcircuit from the down-stroke re lays I and lto the up-stroke relays 2 and 0;

The code relays will serve to transfer the codereceived, to selectively operated mechanism such as station-connecting relays to connect the call- I00, i'urthermore,' if released, will not operate through resistance R, but if operated, will hold operated when resistance R is included inthe signaling circuit.

When any key of the key-sender at the'calling,

or code transmitting station is depressed. the first result is the release of relay I05. Then according to the U-bars I0 selected by the key, the down ing subscriber to the called subscriber as described .in the above identified Patent 2,278,411). Relay 0' stroke registration will be recorded by relays I or 0, or by both or neither. At the end of the down-stroke, relay I00 will release, shorting relays I and 4 and removing the shorts from relays 2 and l which relays will then be available -to receive the code registration on the up-stroke of the key. 1 when the key restores to normal therelays I, 2, 0 and 0 return to their normal condition.

' A description of the-operation, of the system shown in Fig. 10 will now be made. Itis deemed unnecessary to describe. in detail the operation of keyof the key-sex tier, and that 'a thorough understanding of the operation of the system will be had from a description involving the operation of but a few of the keys.

"It will now be assumed that the subscriber at 1 the calling station desires to establish a telephone connection with a subscriber's station to which the key 'ais individually assigned. The subscribenaccordingly, removes the telephone handset from its support and depresses the key a and thenallows it to restore to normal under the action of the restoring spring. Removal ofgthe handset. from its support closes the line loop III ; the .sytem which "follows the actuation of each The operating'windings of relays I and 0 are short-circuited by the armatures and back contacts of relay I03. l 1

, When the key is depressed, contact C is opened andremoves the subset S'fromthe line loop caus- -ing relay I05.-to release. Relay I03 being slow to release; holds, operatedsu'flicientlylong to permit the closure of either-contact A or B, orbo'th, by the actuated key a, to, reestablish the loop .circuit by way of resistance R, as .will' appear scribers telephone set from the line L.

e-opening of contact C is followed immediately by the closure of contact A effected by the operation of key a. In'the schematic showing ,of the key-sender K in Fig. 10, the contact D is co tacts are considered to be out of-enga'gement, ,as shown. \This contact engagement persistssubstantially untiLthe keya reachesthe end of its opened... 1

During the contact A, a circuit exists which may be .traced from the'upper terminal of the secondary wind-i of transformer III, rectifier Ili, windings of relays I05 and I00 in parallel, rectifier IIS, tip conductor of line L resistance R, rectifier V}, con.- tacts D and A, ring conductor of line L, rectifier.

III'I', operating winding of relay I, left armature and front contact of rela I 03', rectifier I I2, to the lower terminal of the secondarywinding of transformer II I. Relay Ioperatesin this circuit and, at its left armature and front contact, looks] I j to battery at the outer armature' and back con-I performs a switching functionwhioh may be utilized to control theoperationot a station-con necting switching device in a manner known in the art.

presently. *Co'ntact "C, open, removes the sub-' 1 I no in engagement with contact A, and all other downastrokegwhen the icon circuit is completely engagement of contact D with..-

tact-ofrelay I05. At its rightarinature, relay v the key 0'; reaches the end of its downthrough the subscriber's subset. As hereinbei'ore. 7; stroke, the line'loop'is completely'open so that to transmit a station-selecting impulse which is registered by the relay I.

With the return to normal of 'key a, the contact C is again closed causing relay I05 to again operate to remove the locking battery from the relays causing the operated relays to release and restore their armatures.

It-will now be assumed that instead of actuating key a the calling subscriber actuates key b inorder to efl'ect a different station selection,

Relays'l05 and I03 will be operated as described hereinbefore.

. As soon as key b starts its down-stroke, the

contact C is opened to remove the subscribers set Relay I05 accordingly releases,

from the line. and relay I03 holds operated as described in connection with the actuation of key a. During the down-stroke of key b no operation of the ratchet wheel 69 (Fig. 9) is eflected and therefore no rectifier connection to the line results.

to be rendered-effective during thedown-stroke of the key.

When the key e is depressed, contact is openedand contacts D and l engage contacts A and B, respectively, of thekey-sender shown schematically in Fig. 10. While these contactsare in engagement, positive and negative current impulses traverse the line loop to cause the operation of code relays I and 4. The oper ating circuit for relay I is the same as described in connection with the operation of key a. Relay 4 operates in a circuit which may be traced fromv the lower terminal of the secondary winding oftransformer III, rectifier II3, front contact and right armature of relay I03, operating winding of code relay 4, rectifier I09, contacts 3 and D rectifier V ,.resistance R, tip conductor of line L,rectifier H4, windings oi relays I03 and I05 in parallel, rectifier I I1 to the upper terminal of the secondary winding of transformer III. Relays I and 4 accordingly are operated when key e is actuated to register the signal transmitted by'this key.

I When the key e reaches'the end of its downstroke, the loopcircuit is opened causing the release of relay I03, but sincevno impulses are transmitted during the up-stroke of key e, the

release of this relay performs no useful purpose in this particular instance. -When the key e reconnect the subset S However, when the key b reaches its lower limit, the line circuit is completely opened and relay I03 releases, shorting relays I and l and removing the shorts from relays 2 and 8 which latter relays are then available to register the impulses transmitted during the up-stroke of key b. Durwheel 69 is rotated to-cause a closure of contact A, or contacts 8283 of Figs. Mind 4. That is, referring to the schematic K of Fig. 10,. he contacts U and A engage each other during the I up-stroke'of key b. -During this engagement a circuit may be traced extending from the upper terminal of the secondary winding of transformer III, rectifier .II5, windings of relays I05 and stores to normal, contact C is again closed to reto the line L and to reoperate relay I01),

The condition will now be described in which I impulses aretransmitted over the line loop during both the downand up-stroke's'of a stationselectingkey. For this purpose it will befas- 'surned that the -calling subscriber actuates the stationgselecting key of It will be noted, by ref- 'ing the return or up-stroke of key b the ratchet I03 in parallel, rectifier II8, resistance R, rectiver V contacts U and A, rectifier I0], back contact and left armature of relay I03, operating winding of code relay 2, rectifier III to.

the lower terminal of the secondary winding of transformer III. Relay 2 operates in this.circult and at its front-contact and right armature locks in an obvious circuit. At its left armature and front contact, relay 2 may control the operation of a station-connecting relay. Thus; 'on the return stroke ofkey b, a positive impulse is transmitted over the line and is registered by relay 2. When key b reaches its normal position the receiving circuit is restored to normal andthe contact 0 is closed to reconnect the subscribers telephone set to the line.

The station selections thus far described were effected by the transmission of pulses of a sin- -gl'e polarity only, which were generated on the down-stroke of the key a and on the upj-stroke of key b, respectively. It will now be described .how a station selection is effected by the trans! mission of a signal comprising both positive and negative current impulses generated during, thedown-stroke of a key. For this purpose; it will be assinned that the subscriber at station S.actuerence to the table ,(Fig; 12), that both contacts A and B function during the-down-stroke of key 9' and that only contact A is involved in the up-stroke thereof.

When the key 9 is depressed, contact 0- is opened and contacts D and D engage contacts A and B, respectively. The engagement of contactsD and D with contactsA andB effectively connects rectifiers V 'and V, respectively, across the line L by way of resistance R in the manner describedin connection with the oper atio'n of key e; Relaysl and 4-, accordingly, operate and 'lock, aspreviously described, during the down-str'okeof key g. When the key g reaches the end of its down-strokes the loop circuit is completely. opened as previously described, so

that relay I03 restores its armatures. Relay I03,

in restoring its-armature s, prepares relays 2 and 8 for the reception of impulses transmitted fduring theup stroke of the'keym. During the up-stroke of key 9, contacts U 'and;A of the keysender K come into engageinent' so that a positlve currentimpulse'traverses acircuit extending fromv theupper terminal of the secondary winding of transformer l'll,'rectifler II5, wi'nd-' ings of relays {05 and I03in parallel, rectifier IIO, upper conductor ofline L, resistance R, rectifier V contacts UP and A of the key-sender, lower conductor of line L,' rectifier 1, back contact and left armature of relay I03, operating -windln g of code relay-'2, rectifier lI2tothe lower terminal of thesecondary winding of the transv former'II I. Relays 4, I and 2, accprdingly, re-.

ates the key e, which, in accordance with the table (Fig. 12) causes both contacts A and 3 spondto the operation of key g of the key-sender station corresponding to the key-g.

and cooperate .to eflec't the-selection of} called In describingthe operations 'of the circuit, I

which follow the actuation of keys 0., b, e, and a, the following conditions have been covered. I

- 1.- The transmission of a single pulse of positive-direct current during the down-stroke of key 'a. l

2. The transmission of a single pulse of posi-' tive direct current during the up-stroke of key b. 1 a

3. The transmission of a positive and a negative current impulse during the down-stroke of key 6.

) alternative to that shown in Fig. 10., The registration, or code relays l, 2, 4 and 8 of Fig. 10,

can be made to operate on a half-cycle of curfore, that a full half-cycle of each. polarity is included in the contact closures for each'direction of operation of a station selecting key. For

. GO-cycle supply, which is the intended frequency of the supply source H in Fig.. 10, this would than the impedance of .the subset s: and will be further increased to the full supply voltage when the loop is opened at the down-stroke ofa key. The-full secondary-voltage of transformer 13 is applied to the control gap of the tube 225 associated with relay 205 while-that applied to the tube 223 associated with relay 203 is reduced by the potentiometer 224. The batteries HI and 2, the Iormer of 130 volts and the latter of 80 volts furnish anode potential for the tubes 223 and 225.

The values are so chosen that neither tube breaks down as long as contact C is closed, while the increased potential drop through resistance R, when C is opened, is sufilcient to break down tube 225 and operate relay 205. Relay 203 will operate only when a key reaches the end of its ing the full supply voltage at the terminals of require a minimum closure of about 20 milli-., I

seconds each way. vIn the key-sender illustrated in Figs. 1 to 9, inclusive, the necessary time .closure oi the contacts is insured by the cou- 'pling springs '61 which guarantees contact closuresof sufflcient lengths of time without imposing on .the subscriber any requirement as to the manner in which the keys of the key-sender are to be operated. Another way of coping with the situation referred to above is to increase the supply frequency, so that a full cycle will occupy less time.

. rent of the proper polarity. It is required, theredown-stroke and opens the line loop thus applytransformer D. Relay 205 activates the regisary windings of transformers E and F, and provides an operating path for relay 203.

A description of theoperation of the receiving circuit shown in Fig. 11 will now be made a, b, e, and g will be operated to effect four different station selections.

Prior to the operation of the key a. in making a first station selection, the circuit elements are in the condition illustrated. When the key a is operated, the contact C is opened in the manner previously described, to remove the telephone set S from the line. The operation of key For example, if a frequency of 200 cycles is used,

the minimum contact closurerequired would be slightly over 5 milliseconds, which could be obtained without the introduction of the coupling spring 61' in the key-sender.- However, this .would reduce proportionately the time ofoperation of the code. relays. The circuit shown in Fig. 11 has been dev ised to illustrate the use of a .supply source designated 2I0,' which has a frequency of approximately 200 cycles, and gastube type receiving equipment which has the speed of operation required at such a frequency.

The arrangement ofthe subset is the same as in Fig.10, and the functionsof the several' parts of the receiving circuit are substantially equivalent to those of the corresponding elements of thecircuit of Fig. 10. The registration relays I, 2, 4 and 8 are operated through-gas-fllled 3 tubes 230, 234, 233 and 235,.respectively, which look when operated.

Control relays 203 and 205 perform substantially the same functions as relays 103 and I05,

' respectively, of Fig. 10 and have the samemar ginal discrimination. This discrimination is on an operate basis rather than a release basis as in the circuit of Fig. 10. The input transformer Dis bridged directly across the line loop L andthe 200-cycle supply 2| 0 is fed through resistance 220. .Thusthe potential across the transformer D will be a minimum'when contact C is closed; 'will be greater when this contact is opened, since resistance Risconsiderably higher a causes contact.A to engage the contact D of the key-sender schematically shown at K, so

that the increased potential dropthrough re-.

sistance R is sufilcient to break down the tube 225 to 'cause'the operation of control relay 205. The'control gap of the tube 225 extends from ground, through battery 22I, control electrodes of tube 225, secondary winding of transformer D, through battery I to ground. As indi- 'cated, the potential impressed on this tube is now of suflicient magnitude to cause the tube to fire, so that relay 205 operates. Relay 205 operates in a circuit extending from grounded 'battery 22I, main gap of tube 225 to the anode thereof, winding of relay 205v to groundby way of condenser 250. The condenser 250 charges up at this time and when relay 205 operates the resistance capacity network serves to hold .relay 205 operated for a small intervalof time before it releases. Resistance 249 is used primarilyto prevent contact sparking.

rAt its armature, relay 205 applies ground potential to the point 25I whichis common to the secondary windings of transformers E and F. By

virtue of this ground. connection the registration circuit including relays L2, 4 and 8 beccmiesactivated. Relay 205 also supplies ground to the anode circuit of tube 223 to prepare relay 203 for operation.

A circuit may now betraced from the upper terminal of the secondary winding of transformer 2| I, upper conductor of the line L, resistance R,

rectifier-V contacts D and A, lower conductor of line L, primary winding of" transformer E, rectiller 2", to the lower terminal of the secondary winding of transformer 21 I. The voltage appearing across reslstance'221eonnected across the secondary winding of transformer E causes-the tube 230 to "iflre." The circuit for tube 230 extends from ground, battery 23 I; control electrodes of tube 230, back contact .and left armature of tration circuit by putting ground on the second- -and for this purpose it will be assumed that keys downstroke of key a and at its armature may coning of relay I, to ground by way of battery 253.

The circuit to'battery 253 is shown in broken lines to indicate that this circuit, in which the operated, tubes lock, may be controlled in any suitable manner so as to release and reset the register relays.

0 When the tube 234 operates, code relay';2 oper- While the locking circuit could be placedunder the control of relay 205, it might well be controlled in some other manner, such as bya supervisory relay in the telephone system.

Thus code relay I operates and locks during the trol the operation of station-connecting switching devices to eilect a connection to the telephone line to which the key a is assigned.

When the key a reaches the bottom of its down-stroke, the line loop is opened causing the 9 application of the full supply voltage to the terminals oi transformer D. When this occurs relay 203 operates since the voltage now applied to the control electrodes of tube 223 is of such a magnitude as to cause the tube to fire. remains. operated. Relay 203, operated, opens the circuits to the control electrodes of tubes 230 and 233 and completes the circuits to the control electrodes of tubes 234 and 235. Thus relays 2 and 8 winding of transformer E, rectiiler- 2Il, tothe lower terminal ofthe secondary winding of transformer 2Il.- Thus a voltage appears across re sistance 221 which causes the operation ofgas tube 234. The circuit for tube 234 may be traced from ground, battery 23I, cathode and control electrode oi" tube 234, front contact and left armature of relay 203, resistance 221, to ground by way of'the front contact and armature of relay 205.

ates in a circuit extending from battery 253, winding of relay 2, anode and cathode of tube'234 to ground by way of battery 23I. Relay'2, operated, controls the operation of a station connecting relay, not shown, to'complete a connection'to the line towhich the key b is assigned.

-When the key 17 reaches its normal position, contact C is closed to reconnect the subset S to the line, whereupon the circuit is restored to normal, as previously described.

When key 6 is actuated in initiating a call to a called subscriber's station, both contactsA and B are actuated on the down-stroke of the key as ind cated by the table, Fig. 12. When this occurs,

Relay 205- 25 are rendered available to register the impulse transmitted during the up-stroke of the key a. Which ofrelays 2 or 8, if either, operates depends upon the polarity of the transmitted impulse. As shown by the table, Fig. 12, no rectifierconnecting contacts are operated on the up-stroke of key a so that the key restores to normal without effecting the transmission of an impulse during its return movement. When key a returns to normal the contact C is closed to reconnect the subset s to the line. This reduces the potential 4 applied to the control electrode of tube 225 andthe tube deionizes. The condenser-resistance network associated with the relay 205 serves to hold the relay operated for a brief interval of time (in the order of a few milliseconds) and then permits 4 it to release when the potential applied to the control electrode is reduced to a;value insufficient to sustain ionization. This reduction in potential occurs, as stated, when the subset S is reconnected to the line incident to the return of a-key a to its normal position. Relay 205, released, opens the anode circuit of tube 223 permitting this tube to deenergize and release relay 203. The circuit is now restored to its normal condition.

Should key I) be operated, contact C would open in a manner now apparent, and relay 205 would operate as described in connection with the operatlon of key a. Relay 205 prepares the register circuit for the receipt of the transmitted impulses.

As indicated by the table, Fig. 12, no. rectifier con- 60 necting contact closure is effected during the down-stroke of key 1).. The loop circuit is opened when the key reaches theend of its down-stroke. whereupon relay 203 operates in the manner hererelay 205 operates when contact 0 is opened,- and code relays I and i iunctionto register the transmltted' lmpulses. Relay I operates to register the positive impulse in the same circuit described'in connection with the operation of this relay followingthe actuation'oi key a, and relay 4 operates as a result of the transmission of the negative impulse. The circuit for the negative impulse may be traced from the lower terminal of the secondary winding of transformer 2| I, primary winding of transformer F. rectifier 2I2, lower conductor.

of line L, contacts B and l) of the key-sender K, rectifier V, resistance R, upper conductor of line L, to the upper terminal of the secondary winding of transformer 29 5. Due to the current flow in 0 primary'winding of transformer F, there is produced a voltage drop across resistance 229 which results in the operation of tube 233. The circuit for tube 233 may be traced from ground, battery.

- 23I,cathode and controlelectrode of tube 233,

5 back contact and right armature of relay 203, re-

sistance 223,- to groundat the front contact and armature of relay 205. Code relay 4 now operates in a circuit extending from grounded battery 253, winding of relay 4, anode and cathode of tube 233, battery 23I to ground. Thus. code relays I and 4 --operate as a result of the down-stroke of key e to register the signal characterized by the combined positive and negative impulses transmitted.

These relays may be used to control the operation of switching devices which effect a conhection to 7 the called lineto which key e is assigned.

inbefore described. With relay 203 operated.code

' that the key restores to normal without efi'ectcuit may be traced from the upper terminal of the secondary winding of transformer 2| I, upper conductor of the line L,- resistance R, rectifier V. contacts A and U of the key-sender schematically shown at K, lower conductor of the line L, primary A When key e reaches the end of. its down-stroke the line loop is opened causing control relay-203 to operate and to substitute code relays 2 and ,0

for code relays I and 4 in their association with the line circuit, whereby code relays 2 and 0 are rendered available to register the impulses, if any, transmitted during the up-stroke of key e. As in dicated by the table, Fig. 12, no impulses are transmitted during the up-stroke of key e so ing any further contact operations. When itreaches its normal position, the'key e closes contact C to reconnect the telephone .set S to the line which results in the release ofrelays 205 and 203. v ,i

In the event key 9 is operated to eflect a connection between the subscribersstation' at which the key-sender K is located and a subscriber's I line to which key 0 is assigned, contacts A and fortr B, as shown in the table, Fig. 12, function durv ing the down-stroke .of the key to transmit vapositive and a negative impulse over the line. In

response to these impulses code relays l and 4 operate in the same manner as' when key'e was employed. When key g reaches the end of its down-stroke .the line circuit is opened to cause relay 203 to operate so as toprepare code relays 2 and B for the registration of the impulses, if any,- transmitted during the up-stroke of the key. As shown in the table,-Fig. 12, the contact A .is employed during the up-stroke of key g to cause the transmission of a positive impulse over the 'line which operates code relay 2. It. is be-,

lieved unnecessary to describe in detail the circuits completed during the up-stroke of key 9 which result in the operation of code relay 2, since they are identical to those efiected during the up-stroke of key b previously described. Suffice it to say that relay 2, operated during the up-stroke of key g and -relays.l and 4, operated'during the down-stroke of key g.function collectively to control the operation "of switchingequipment (not shown) which results in the extension of a connection to the telephone line assigned to key g.

By referring to Fig. 12 it will be noted that certain signals effected by the key-sender of this invention are characterized in the same-manner. For example, the signals transmitted incident to the actuation of keys'a and b are each characterized by an impulse of positive polarity; also. the signals transmitted incident to the actuation of keys d and h are each characterized by an impulse of negative polarity; similarly, the sig-' nals transmitted incident to the actuation of I keys e and i are each characterized by a positive Thus more than one signal is characterized in thesame manner.. The

and a negative impulse.

discrimination between signals having the same .characterization is effected by transmitting one signal, such as the signals transmitted incident to the actuation of keys a, d and e during the first portion of a signal transmitting period, whereas the'signals transmitted incident to the betwee tion by ransmittingone signal during one-portion oi -a signaltransmitting period and another.- signal during adifl'erent portion oi the signal transmitting period.

What is claimed is:

1. In a signaling system in which a called sta-' tion is characterized by a particular combination of impulses and in: which complemental portions of the station-characterizing impulse combination are transmitted over a line consecutively home-calling station, a plurality of keys at the calling station each having adown-stroke and an- 11 -stroke, and means controlled by said keys mitting one portion of the station-characterizing impulse combination over the line during the down-stroke of a key and for transmitting the otherportion. oi the station-characterizing impulse combination over the line during the up-stroke of the key. V

2. In a signaling system in whicha called station is characterized by a particular combination I otpositive an d/or negative current impulses-and I current imp in which complemental portions of the stationcharacterizing impulse combination are transmitted over a line consecutively from a calling station, a key at the calling station having a down-strokeand an up-stroke, means efiective" during the down-stroke of said key {or causing the transmission over the line of the first complemental portion of the stationcharacterizing impulse combination, and means effective during the up-stroke of said keyfor causing the transmission over the line of a second complemental portion of the station-characterizing impulse combination. V

3. In a signaling system in which a called station is characterizedby two groups ofpositive and/or negative current impulses and in which I the two groups of impulses are transmitted con- 'secutively over a line extending from a calling station, -a signal transmitting key at the calling station whose complete signal transmitting operation embraces both itsdown-stroke and its up:

stroke, and means controlled by said key during v its down-stroke and its'u'p-stroke for causing the transmission 'of a difierent one of the two groups of current impulses.

4.,In a signaling system in which a station- 3 selecting signal is characterized by two separate groups of impulses, each of which is made up of one or more positive'and/or negative impulses; a line, a key having a doWn-stroke-and an up-stroke, and means controlled by said key for-transmitting one. of the groupsof impulses over said line during the down-stroke of said key andv the other group of impulses during the j up-stroke of said key.-

' 5. In a signaling system in which a station; selectingsignal ischaracterized bya particular combination 017;. positive and/or negative cur- ,rent'impulses transmitted, in code, .over'a line. 40 8. keyh'av-ing a down-stroke and an up-stroke.

and means controlled by, said key mtransmitting, in code, a portion .of the signal-characterizing impulse combination only during the down-stroke of said key and for transmitting;

in code, another portion of the signal-characterizing impulse combination only. during the up-stroke of said key.

6. In a signaling system-in which astation identifying signal is characterized by two groups of current impulses, a sending station; a receiv- '-ing station, a key atsaid sending station having a down-stroke and an upl-strokejmeans controllednby saidkey during. its down-stroke for transmitting one of the gr ups of current impulses overthe line, and

eans controlled by said key during its up-stroke' for transmitting the other groupfof impulses over the line whereby the transmisslon of a station-identifying sig-: 'nal over said line is completed ,only when said key is operated through both its down-stroke and its up-stroke. c

' 'z. m combinationin a. system. a]

sending station, arecei'ving station} a two-'-wire line'inter-connecting said stations, asource 0! alternating current connected to, said line, means at said sending station for transmitting direct s from said source over said line, i a key 'at said sending station having a cycle of operation,whicli includes the down-stroke and the up-stroke thereof, means controlled by said key for connecting said direct current impulse transmitting means tosaid-line during the downstroke or said key-and again duringits .up-stroke.

' whereby-direct current impulses are transmitted consecut vely over said line, and means at said receiving station for registering the impulses transmitted over said line.

8. In a signaling system in which two groups of positive and/or negative current impulses are transmitted over a line consecutively to characterize a station-selecting signal, a key having the impulses transmitted during the down-stroke f of said key and a group of translating devices for responding to and registering the impulses transmitted during-theup-stroke of said key, and means controlled by said key for rendering each of said groups of translating devices available to register the impulses transmitted during a corresponding stroke of said key.

9. In a signaling system in which a stationconnecting signal transmitting and receiving stations, of a signal receiving circuit comprising two groups of selectively responsive translating devices, a source of alternating current connected to the line, and means for effecting the consecutive transmission of direct current impulses of.

Opposite polarities from said source over said line comprising a key-type sender including a plurality of manually operable keys, a pair of oppositely p'oled rectifiers', means controlled by a certain one of said keys and effective during the down-strokethereof-for connecting one of said 'rectiflers' between the two wires of. said line to cause the transmission of a direct current impulse of one polarity over said line whereby a certain one of the selectively responsive translating devices of one of saidgroups is operated,

meanscontrolled by "said keywhen it reaches the end of its down-stroke for preparing theselectively responsive translating devices of the other 5 of said groups for operation, and means conselecting signal is characterized by two separate combinations of positive and/or negative current impulses, a key having a down-stroke and an up-stroke. meansv controlled by said key fdr transmitting the two separate combinations of positive and/or negative current impulses over said line consecutively, a group of translating devices for registering the combination of impulses first transmitted oversaid line, a group of translating devices for registering the combination of impulses next transmitted oversaid group of translating devices effective to register the first transmitted impulses, and means controlled by said key upon completion of its downstroke for rendering the second said group oi translating devices effective to register the next transmitted impulses.

10. The combination in a signaling system in which certain signals are characterized by directcurrent impulses transmitted consecutively over a two-wire line interconnecting signal transmitting and receiving stations, of a signal receiving circuit comprising two groups of'selectively responsive translating devices; a source of alternating current connected to the line, and" '5 means for effecting the consecutive transmission of direct current impulses from said source over the line comprising a key-type senderincluding. a plurality pf manually operable keys, a recti-. fler, means controlled by a certain one of said keys and effective duringthe down-stroke thereof for connecting said rectifier between the two wires of said line to cause thetransmissi'on of a line, means controlled by said key when beginning its down-stroke for rendering the first said trolled by said key and effective during the upstroke thereof .for connecting the other of said rectifiers'between the two wires of said line to cause the transmission of a direct current impulse of a different polarity over said line, whereby a certain one of the selectively responsive translating devices of said other groupis operated. i

12. The combination in a signalingsystem in which certain signals are characterized by two groups of .direct current impulses, each comprising a positive and a negative impulse, transmitted consecutively over a twowire line interconnecting signal transmitting and receiving stations, a signal receiving circuit comprising two groups of translating devices, each group including a device selectively responsive to impulses of each polarity;

a source of alternating current connected to the .line, and means'for effecting the consecutive transmission of two groups of positive and negative direct current impulses from said source over said line,comprising, a key-type sender including aplurality of manually operable keys, a

pair of oppositely oled rectifl'ers, means controlled by a certain one of the keys of said sender and effective during the down-stroke thereof-for simultaneously connecting both said rectiflers between the two wires of said line to cause'the transmission of a positive and a, negative direct current impulse over said line, whereby the translating devices of onset said groups thereof are operated, means controlled by'said key when it direct current impulse over said line to operate a certain one of the selectively responsive trans-. lating devices of one of said groups, means controlled by said key: when it reaches the end of its down-stroke for preparing the other of said groups of selectively responsive translating devices for operation, and means controlled by said key and effective during the up-stroke thereof for reconnecting said rectifier between the two wires of said line to cause the transmission of'a second direct current impulse over said line whereby a certain one of the selectively responsive translating devices of said other group is operated.

11, The combination in a. signaling system in which certain signals are characterized by direct current impulses of opposite polarities transmitted consecutively over a two-wire line interreaches the end of its down-strokefor preparing the translating devicesof the other group thereof for operation, and means controlled by said key and effective during the up-stroke thereof for reconnecting both said rectiflers between the two wires of said line to cause the transmission of a a positive and a negative direct current impulse over said line, whereby the translating devices of the other of said groups thereof are operated.

- 13. The combination in a signaling system, of a line, an impulse transmitter comprising a key having a down stroke and an up-stroke and capable of transmitting an impulse over said line for eaclr stroke thereof, impulse receiving equipment for receiving the impulse transmitted by said key during its down-stroke, impulse receiving equipment for receiving the impulse transmitted by said key during itsup-stroke, and means controlled by said key for rendering said impulse a line; an impulse receiving circuit, and means for transmitting impulses oversaid line to said impulse receiving circuit comprising a pair of pulsing contact springs whose period of closure determines the length of impulse transmitted over said line, a key, a sectionalized rod having one section thereof in operative association with said contact springs and the other coupled to said key, whereby said rod is rotated when said key is actuated to effect the closure of said contact springs, and means comprising a spring coupling the two sections of said rod, whereby the period of closure of said contact springs incident to the actuation of said key is renderedindependent of the speed of operation of said key.

15. In combination in a key-type sender for transmitting station-selecting impulses of positive and/or negative polarities, singly or in combination over a line,.rectifying means for determining the polarity of the transmitted impulses, a

asea'm contact means for connecting said rectifying means to said line, a key having a down-stroke and an up-stroke, levers operatively associated with said key, a ratchet wheel; a pair of arms depending from said levers and operatively associated with said ratchet wheel in such a manner ciated with saidratchet wheel for operating said contact means whereby said rectifying means is connected to said line once for each of the upand down-strokes of said key.

HENRY M. BASCOM. FRANCIS A. HUBBARD.

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