US2233056A

US2233056A - Teletypewriter switching system

Info

Publication number: US2233056A
Application number: US273384A
Authority: US
Inventors: Wayne V K Large; Fred J Singer; White Charles
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1939-05-13
Filing date: 1939-05-13
Publication date: 1941-02-25
Anticipated expiration: 1958-02-25

Description

E J. SINGER C. WHITE ATTOR/VE Y m VJCLARGE fil/9X l /NVENTORQ W. V. K. LARGE ET AL TELETYPEWRITER SWITCHING SYSTEM Filed May 15, 1959 Feb. 25, 1941.

Patented` Feb. 25, 194i UNITED STATES PATENT OFFICE 2,233,056 TELETYPEWRITER swITOHlNG SYSTEM Application May 13,1939, senai No. 273,384

11 Claims.

This invention relates to teletypewriter switching systems and particularly to service observing circuits used in connection .with cord circuits in manual teletypewriter switching systems. n

An object of thisinvention is to provide a service observing circuit for use in connection with a cord circuit in a manual teletypewriter switching system, in which the same supervisory signals as appear in the cord are reproduced in the service observing circuit.

A further object of this invention is to provide a service observing circuit which is interconnectable with different types of cord circuits at different times, said cord circuits having apparatus units with battery of different voltages connected in parallel with apparatus -units in the service observing circuit. n

A feature of this invention is a service observing circuit for` usewith a cord circuit in a man-` ual teletypewriter switchboard, said observing circuit having a lamp signal corresponding to the cord supervisory answering lamp and another corresponding tothe cord supervisory calling lamp, said service observing lamps being arranged to light steadily, Hash or darken in unison with their corresponding cord lamps, reproducing the cord supervisory signals in the service observing circuit.

A further feature of this invention is a unidirectional current device used in a circuit connectable at different times to different types 0f circuits, wherein the voltages of the connecting circuits are not' the same, to prevent the false operation of an apparatus uniton one of the Ydifferent types of connection.

It is old in the teletypewriter art `to provide means for flexibly inserting a teletypewriter for monitoring purposesin the transmission lead of a cord circuit, in series With the teletypewriter switchboard operators teletypewriter circuit. Such an arrangement is disclosed in Patent 1,884,- 567 to J. J. Catogge, October 25, 1932. Service observing is preferably performed in a separate room out of sight and hearing of the operators.

As far as applicants are aware, however, no facilities are available to perform the functions of their circuit herein, namely, to provide a service observing circuit for cooperating with teletypwriter switching cord circuits, which, in addition to reproducing the' teletypewriter communication signals transmitted through the cord, reproduce also the cord supervisory signals. The advantage of this will be `apparenttoanyone skilled in the art, as it not only provides -an indication that the cord circuit supervisory signals are functioning properly, but furnishes also a check on the manner in which the call is handled by the operator. This is invaluable in the training of operators and in maintaining a high standard of service. In arranging the service observing circuit herein to connect to a cord circuit, instead of to the subscribers line circuit, a number of advan- -tages over other service observing arrangements are afforded. In observing circuits, in -which connections are made to line circuits, it is necessary to provide either an entire reappearance of the subscribers line lampsand jacks in the location where the service observing is performed, the expense of 'which is prohibitive, or to make temporary patches to a group of selected line i circuits at various times. These temporary connections are objectionable for a number of reasons among which are the following: (1) Setting them up and changing them periodically involves expense. (2) The patching is generally performed at the distributing frame by means of a shoe and a long -cord which is cumbersome and interferes with the normal work on the distributing frame. (3) Since a list of numbers of Ithe lines which are to be observed must be made up by some operating oiiicial, such as the chief operator, turned over to the wire chief and then passed on to the maintenance men, and since anyone who has accessto the distributing frame may readily observe the numbers of the lines which are under observation,

it is difficult to keepv the numbers ofthe observed lines secret. (4) When patch connections are made to selected line circuits, the observing operators are limited to observing only on calls involving the particular lines in the selected group. There may be long intervals during which the observing operator is'idle awaiting calls in said selected group.

These difficulties are obviated when the service observing circuit is connected tothe cord circuit instead of tothe line. The service observing Voperator receives` indications whenever; the

from the following description when read in connection with the associated drawing.

Fig. 1 is a portion of a cord and operators position circuit used at a telegraph or teletypewriter switchboard in interconnecting telegraph or teletypewriter subscribers, or to extend a subscribers line to a trunk or to interconnect two trunks. The circuit which is well known in the art, has been modied to exibly interconnect with the service observing circuit of the invention herein;

Fig. 2 is a service observing circuit which interconnects with Fig. 1. 'Ilhe observing circuit is used in observing the service provided on connections established by meansof -the cord circuit per Fig. 1; and

Figs. 3 and 3A are alternative embodiments of a portion of Fig. 2.

It will be assumed that a call is incoming through the answering jack t0 the left of Fig. l. In response to the operation of the lamp signal associated with the jack indicating that a -call is incoming, plug -|0| of Fig. A1 is inserted into the answering jack. A circuit is thereupon `established from ground, through the sleeve of the answering jack, sleeve of plug |0| and winding of relay |02 to battery, operating relay |702.

The ring conductor of the jack is extended through the ring of plug |0| and the ring conductor ofthe cord, through resistance |-25 to the cord circuitl polar relays indicated by I0. These relays and other portions of the cord and opera- 'tors position 'circuit which are not shown in detail in Fig. 1 are omitted as they are known in the art and function in a known manner. Such arrangements are disclosed in numerous patents,

Vsuch as the patent to F. S. Kinkead et al.

2,024,581, December 17, 1935, to which reference is made. The Kinkead patent discloses one ernloodiment -of a subscribers *lineA and station cirthe cord per Fig. l has been used in answering an incoming call.

lIt is to be understood that at any operators position there are numerous cord circuits, any one of which may be chosen by an operator thereat in answering and extending a call. Jacks |23 and |24 and their associated lamps |2| and |22, respectively, are located at a service observing board which is ordinarily located in a room separate from that in which the switchboard containing the cord circuits and jacks per Fig. 1 are located. All or any part of the cords in the switchboard may be similarly extended to the observing position so that the observing operator may observe on any connection handled by the operators at the particular board being observed upon a particular cost so extended. In certain cases, such as in large cities where more than one switchboard may be required and where it is economically feasible, all of the cord circuits in all of the boards may be connected as indicated in Fig. l to a single centralized service observing board which may be used to observe on all of the telegraph or teletypewriter switching at the various boards in a particular area.

When double ended plug 20| is inserted in jacks |23 and |24, the telegraph signal transmission conductors in the answering end of the cord per Fig. 1 .areopened and the transmission conductors .associated with plug 202 in the service observing circuit are connected in series therewith. Similarly, the telegraph signal transd mission conductors in the calling end ofthe cord per Fig. `1 are opened and the transmission conductors associated with plug 203 in the service observing circuit are connected in series therewith. These circuits may be traced as follows: From the ring conductor of the answering jack incoming from the calling station, 'through the ring yor ,middle conductor of plug |01, through the tip of jack |23, the Ashunting path through resistance |25, now being open due to the insertion of plug 202, through the tip or right-hand conductor of plug 202, th'e bottom `break contacts of key .204, which contacts are in 4engagement when key 204 is in the normal or unoperated position, through resistance 200, the top break contacts of key 204, `which contacts are also `in engagement, the'ring or middle conductor of plug 202, ring 'of Ajack |23 to the polar relays ||0 of the cord circuit. Forth'e calling end of the cord,

the circuit extends 'from the ring or middle conductor of plug |20, `,through the tip or left-hand conductor of jack |24, the shunt path through resistance y|20 being 'open due to the insertion of plug 203 in jack |24, through thetip'of plug 203, top break contacts of key 205, resistance 201, bottom break contacts 'of `key 201, through the ring or middle conductor of plug 203, ring of 'jack`l`24 to the polar relays ||0 of the .cord circuit perFig. 1.

The telegraph signal transmission path of each end of the cord circuit per Fig.`l is thus extended into the service observing circuit per Fig. 2. By operating key 204 associated with the answeringcnd of the cord, the service observing operator may interconnect rher position circuit in series with the answering end ofthe cord. Similarly, by operating key 205 associated with the -calling end of the cord, the service observing operator may rinterconnect her position circuit Yin series with the calling end ofthe cord. When key 204 is operated, the lpath heretofore traced through resistance 206 is-disconnected at the top and bottom break contacts of key 204 and the path through the service observing circuit is substituted therefor. This path may be traced through the top make-contacts of key 204, winding ofreceiving magnet 208, sending-contacts 209, break key 2|0to the bottom make contacts of key 204. Similarly, when key .205 isoperated, the path throughresistance 201 is broken at the top and bottom break contacts of `key 205, and the service observing position is substituted for the resistance through the top and bottom make contacts, of fkeyf205- :If `it isadesired :to insure secrecy, sendingcon- `ta'cts 209 and break key 2 0 inthe service observing 4position circuit may be omitted..` 1If it. is desired to permit the observing operator tocommunicate over the circuit as, forinstance, in the training of operators or for some other reasons, these facilities may be included. .nl

vLamps and IIB associated with the answering and calling ends of the cord circuitperllg.,` 1, respectively, are supervisory lamps. They. are used 'to transmit disconnect signals from the calling and called subscriber to the operator, as well as Arecall signals from the calling or called subscriber to the operator or recall signals from operator to operator in the case of aftandem'connection involving a plurality of switchboards.

They are also used in certain systems of operation, such as straightforward systems, inaddtion to providingdisconnect and recall signals, to indicate successive steps in the establishment "of a call through a plurality of switchboards to the called subscriber. `These lamps may be lighted or fdarkened to convey these signals to the operator. The invention herein provides means for reproducing these signals at the service ob,- serving board, so that the service provided in handling calls may be observed. Essentially, this `is performed by providing a lamp in the service` observing board connected in parallel withthe supervisory lamp associated with each end of the 4with the answering cord may be traced from battery |05 through switch |04, the. filament of lamp |03 to thearmature of relay |01.r For a |09, flashing lamp |00 may be arranged in a large variety of ways,

steady lamp signal, which may serve as a disconnect signal, relay |01 is operated, responsive to control means, not shown, to connect a steady `flashing lamp signal, relay |01 remains in its released condition, as indicated, and relay |08 is operated, responsive to control means, not shown, .to extend the lamp circuit through the armature Vand back contact of relay |01 and the front contactl and armature of relay |08, through alternate open and grounded segments of interrupter The connections which control relays |01'and well known in the artto provide the steady and flashing lamp signals and, since they form no part of the invention herein, are not shown in detail. Notwithstanding the manner in which these signal conditions may be effected in the cord, however, the supervisory lamp conductors at eaclnend of the cord are multipled Vinto the `service `observing circuit to reproduce the signal conditions in a correspondingv lamp associated with each side of the service observing. circuit.

The manner in which this is performed is as- ,filament of lamp 2|2. `Lamp 2|2'is therefore lighted. If a steady ground is connected from A relay |01, relay 2|lremains operated to main- `tain lamp ,2| 2 steadily lighted corresponding 4to the condition of lamp ih the cord. If an interrupted ground is connected from Vinterrupter |00botli lamps and 2|| will flash simultaneously.1 i.

Thereason why relay 2|| is provided instead Y of .connecting the .filament of l lamp 2|2 directly to the sleeve lead of plug 202 to light andvextingush the two lamps directly in parallel will now be explained. l 1 n 'Ihere are at present inservice in the existing teletypewriter switching systems cord` circuits having supervisory lamps operating on batteries of different voltages. For example, some of the ysupervisory lamps operate on 24 volts and others on 4S' volts. `The polar relay controlled lamp in the observing cord makes it possible to provide `observing circuits, having battery voltage ofone value only controlling its lamps, to` function universally with the existing cords having supervisory lamps operating on different voltages. The polar relay is arranged to actuate its armature to engage its grounded contact in response to current flowing in one direction only. Relay 2li is arranged to respond to a current flowing' from the positive terminal of the battery, or ground, to the negative terminal of the battery. It will operate in parallel with lamp when ground is connected to a common point intermediate lamp llland relay 2||. The observing `circuit may be connected to switching cords having negative 48 volt battery connected to their `supervisory lamps. This may be simulated by operating switch |04 toits alternate contact, to `connect 48 volt negative battery |06 Vin series with the filament of lamp For` this condition, even though both relays |01 and |08 are unoperated, sothat the conductor normally energizing the lamp circuit is open, `if lamp 2|2 which lights on 24 volts were connected directly l to the lamp lead, itv would remain lighted at all ground to lamp lighting the lamp. For a.

times while the plugs 202 were connected to jack |23. This is so because the 48 volt battery would preponderate over the 24 volt battery and sufficient voltage would be impressed on lamp 2|2 tomaintain it lighted at all times. This would, of course, be objectionable. The use of a polar relay, such as 2| prevents this from happening, because it will not respond to current flowing from the negative terminal o-f battery |06.I It will respond, however, when groundy is connected through the operation of relay |01 or |08 to junction point |21. Thus;v it should be apparent that vthe service observing circuit per Fig. 2 will function` universally with cords 'per Fig. 1 having batteries of different voltages connected to its supervisory lamps.

' The supervisory circuit associated with the calling end of the cord, namely, batteries ||8 and ||9,switch ||1, lamps H0 and |22, relays ||3, ||4 'and ||5 and interrupter ||2, together with their associated wiring including junction |28, function in the identical manner with that Ydescribed Vfor :their corresponding elements in the answering end o-f the cord.` Similarly, polar relay 2|4, resistance 2|6, lamp 2|5 and their connecting wiring; associated with the calling endl of the cord per Fig. 1, function as do their corresponding elements in the service observing circuit associated With the answering end of the cordl per Fig. 1.` It is `not considered necessary, therefore, to an understanding of the operation of these elements to repeat this description' as it may be readily understood from the foregoing by Vthose skilled in the art.

J Fig.`3 is` an alternative embodiment for-the portionof Fig. 2 shown to the left of dotted line -XX in Fig, 2. In this embodiment a copperoxide rectifying element 30| replaces polar relay 2|| to perform substantially the same yfunction as the relay. As is known, such icopperoxide element, when connected in series `in a circuit, presents a low resistance to current of one polarity and a high resistance to current of the opposite polarity. It is so .connected as t0 present a lo-w resistance to current `flowing from the positive terminal Yor .ground in Fig. 1 through element 30| and the :filament of lamp 302 to negative battery. Thus when steady or interrupted `ground is connected to junction point I 21, lamp 302 will light steadily or iiash in parallel :with lamp whether the iilament of lamp be connected to battery |05 or |06. The lamp 302 can not light when ground is disconnected from junction point |21, even though high volt- .age battery |06 be connected in circuit as the copper-oxide element 30| presents a high resistance to battery .of negative polarity connected to its right-hand terminal.

Fig. 3A corresponds to Fig, 3 and is connectable to the portion of the service observing cir- .cuit cooperating with the calling end of the cord circuit per Fig. l to the right of line YY in Fig. 2'. It is thought unnecessary to repeat its description as it functions in a manner identical with -F-ig. 2A.

What is .claimed is:

1. In a teletypewriter switching system, a teletypewriter cord circuit, a teletypewriter service observing circuit, means in said circuits for interconnecting said circuits directly, a supervisory signal in said cord circuit, a signal in said observing circuit corresponding to said supervisory signal, and means in said circuits for operating said signals substantially in unison.

2. In a manual teletypewriter switching system, a teletypewriter service observing circuit connecting with a teletypewriter cord circuit, a 'first signal in said observing circuit, means in said circuits for operating said signal in unison with a rst supervisory signal in said cord circuit, 'a second signal in said observing circuit, and means also in said circuits for operating said second signal in unison with a second supervisory signal in said cord circuit.

3. In a manual teletypewriter switching system, a teletypewriter cord circuit, a teleltypewriter service observing circuit, means in said circuits for interconnecting said circuits directly and a visual supervisory signal in said observing circuit responsive to control means in a telegraph line circuit connected to said cord.

4. In a manual teletypewriter switching system, a teletypewriter service observing circuit, a visual signal therein and means connected to said observing circuit for operating said signal in response to a teletypewriter subscriber disconnect signal.

5. In a manual teletypewriter switching system, a Iteletypewriter service observing circuit, a visual signal therein and means connected to said observing circuit for operating said signal in response to a teletypewriter subscriber recall signal.

`6. In a manual teletypewriter switching system, a teletypewriter service observing circuit, a visual supervisory signal therein and means connected to said observing circuit for operating said signal steadily to indicate a i'lrst condition and intermittently to indicate .a 4second condition.

"7. In a'manual teletypewriter switching system,

a Aiirst cord circuit, a first electric apparatus element in said circuit, a first battery of a rst polarity ,and of afirst magnitude in electromotive force connected to said element, a second cord circuit, a second electric apparatus element in said second cord, .a second battery of the same polarity .as said first battery and of a second .magnitude .in electrornotive force, substantially different from said first magnitude, connected 'to saidsecond element, a monitoring circuit arranged :to cooperate independently and interchangeably with said rst and second cords, a 'third electric apparatus element in said monitoring circuit, a third battery of the same polarity, and same magnitude in electromotive force as Vsaid first battery connected to said element, means in said circuits for connecting said first .element iniparallel with said third element at a first time, means also in said circuits for connecting said second element in parallel with said -third element at a second time and a unidirectional current device in series with said third .element to .prevent the energization of said third Velement due to said diierence in magnitude.

8. In a teletypewriter switching system, a first lamp filament, a battery of a iirst polarity and ci `a first magnitude electromotive force connected Ebetween ground and a first end of said `filament, a second lamp filament, a battery of said first polarity and of a second magnitude electromotive force, substantially greater than lsaidfirst magnitude, connected between ground and a iirst end of said second filament, a con- -ductor `connecting the second ends of said filafrnents anda unidirectional current device connected .in series .in said conductor to prevent the heating of said filaments dueto said diiierence in magnitude.

9. A circuit having a lamp larnent connected in parallel with the winding of a polar relay, opposed batteries o-f substantially different voltages connected individually to said lament and :said relay, means in said circuit for maintaining said lamp filament darkened and said relay winding venergized in a first manner for a first condition and means connected to said circuit for maintaining said lainent lighted and said winding energized in a second manner for a second condition.

10. In a teletypewriter switching system, a'

in Yresponse to said connection to indicate that i said connection has been established, a teletype-l Writerservice observing circuit, flexible switching means in said kcord and observing circuits for manually interconnecting said cord and observing -circuits in response to said signal, a supervisory signal also in said cord operating in respouse to control means in said calling circuit, a signal in said observing circuit corresponding to said supervisory signal and means in said circuit for-operating said corresponding signal substantially simultaneously -with said supervisory signal.

11. In a teletypewriter switching system, a .manual teletypewriter cord circuit, means in said circuit for connecting said cord to a called teletypewriter circuit, a signal in said cord at a teletypewriter service observing position operating in response to said connection to indicate that said connection has been established, a teletypewriter service observing circuit, ilexible switching means Vin said cord and observing circuits for manually interconnecting said cord and observing circuits in response to said signal, a supervisory signal also in said cord operating in response to control means in said called circuit, a signal in said observing circuit corresponding to said supervisory signal and means in said circuits for operating said corresponding signal substantially simultaneously with said supervisory signal.

WAYNE V. K. LARGE. FRED J. SINGER. CHARLES WHITE.