US1551023A - Telephone-exchange system - Google Patents

Description

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J. W. GOODERHAM TELEPHONE EXCHANGE SYSTEM Filed July 14, 1923 5 Sheets-Sheet 1 Aug. 2s, 1925. 1,551,023 J. W. GOODERHAM TELEPHONE EXCHANGE SYSTEM Filed July 14. 1923 3 Sheets-Sheet 2 QT ai r.,l. W.'GOODERHAM TELEPHONE EXCHANGE SYSTEM Filed July 14, 1923 3 Sheets-Sheet 3 Patented Aug. 25, 1925'.

UNITED STATES PATENT OFFICE.

SOHN W. GOODERI-IAIVI, 0F YONKERS, NEWT YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application led July 14, `1923.

To all whom it may concern:

Be it known that I, JOHN W. GooDnRHAM, a citizen of the United States of VJAmerica, residing at Yonkers, in the vcounty of Westchester, State of New York, have invented .certain new and useful Improvements in rTelephone-EXchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems and particularly to an arrangement for making observations on the service afforded subscribers lines in the establishment of calls.

In exchange syste-ms where machine switching apparatus is employed at the central offices for setting .up connections, it is desirable to take observations, from time vto time, to ascertain the manner in which `the apparatus is functioning and to determine the quality of service being given the subscribers. Such information is no-t only of interest to the telephone company in showing the performance of the automatic switching equipment, but also serves to definitely `ascertain whether complaints .entered by the subscribers against the quality o-f the service are due to failures in the apparatus or because of an improper usage by the subscriber of his telephone instrument, or for any other reason.

In order that this information may be readily and conveniently obtained, a special desk is provided in the central ,office and equipped with apparatus and `circuits for taking all the required .observations on subscribers lines. The observing `operator presiding over the desk may inspect the koperation of all switching mechanism involved in the extension of any particular subscribers line responsive to the origination of a call thereon. The observing equipment is arranged to be associable with any suitable variable number of lines at a time and when ,thus allotted it serves to enable observations .on any calling line in such group. To avoid mistakes, which might arise by interference in the association of the equipment with lines calling simultaneously, the arrangement is such that only one line o-f the group can be connected to saidyequipment ,at a time. When all notations have been taken Serial N0. 651,456.

again be connected to some other line in the group.

The present invention is an improvement on the service observing system disclosed in my Patent No. 1,504,230 issued to J. W. Gooderham Aug. l2, 1924, and more particularly to a sensitive means for receiving the pulses dialled by subscribers whose lines are under observation without materially changing their efficacy in controlling the recording of desired line designations on the registers of central office senders. A further feature 4of the invention relates to the provision of means for preventing `false message register signals during the return to norma-l `of subscribers line switches The object of the invention is therefore to provide a service `observing equipment for use in automatic telephone systems, which will lbe accurate in operations and which will operate without decreasing the e'ciency of lines with which it is associated.

Referring to the drawing, forming a part of this application Figs. l, 2 and 3 when arranged with Fig. 3 below Fig. l and Fig. 2 to the left of Fig. 3, illustrate a, portion of an automatic tele-phone exchange to which .the circuits and apparatus embodying the principles of the present invention are adapted.

Fig. 1 shows, in the upper portion thereof, a subscribers line incoming to the central office fromi whence it extends through the distributing frames to an individual line switch. There is also diagrammatically illustrated a trunk leading from the line switch to a first or district selector, a register sender for controlling selections and a trunk outgoing from the district selector. In the lower part of this figure a similar showin-g is given of a subscribers line incoming to the central oiiice, with t-he exception that in this case line finder switches are used instead of individual line switches for extending calling lines to the district switches. In both modifications of the switching appara` tus, as shown in Fig. l, there is further illustrated an arrangement whereby 'connections may be made with subscribers lines for observation purposes by means of plugs and CII jacks, the plug circuits being attachable to the line conductors at the distributing frames.

Fig. 2 shows an observing operators position at which there is located the necessary devices for taking observations of the service on calling lines.

In the space set off by the broken lines in the upper right hand corner of Fig. 3 there are shown the several elements individual to one of the connecting circuits leading from the jacks shown in Fig. 1 to the observing operators position. In the small rectangle to the left thereof are shown a few of the corresponding elements individual to a second one of these connecting circuits. In the remaining portion of the figure, the circuits and relays common to all connecting circuits are illustrated.

Moreover, in addition to being applicable to the two classes of systems above mentioned, both of which involve central oliice controlled power driven switches, the observing apparatus is also applicable to systems of the step-by-step character. Although the invention is applicable to other types of systems the present disclosure shows its adaptation to a full mechanical system.

Before describing the features of the operation of the observing apparatus shown in Figs. 2 and 3, an explanation will iirst be given of the machine switching mechanism serving the subscribers lines on which the service observations are to be made. As

F mentioned above, either individual line switches, such as line switch 128, or line linders, such as the iinder 132, may be employed for extending the calling subscribers line through to a district selector switch. The district selector 130, shown in connection with a subscribers line served by an individual line switch and the similar district selector switch 134 shown in connection with lines served by line finders, may be of the power' driven type in which the selection of brushes and the movement thereof into engagement with the desired outgoing circuits are accomplished by means of applying a constantly driven element to the movable member of the switch. The struct-ure and operation of switches of this general character are shown and described in detail in the patent to E. B. Craft and J. N. Reynolds No. 1,123,696, issued January 5, 1915. The selective movements of the district switches and also of succeeding switches in the establishment of the connection are controlled by means of the revertive impulse register senders diagrammatically shown at 131 and 135. rThese senders are of the usual type used for controlling power driven switches and receive the record from the calling subscribers dial which later serves to govern the directive movement of the switches. A register sender of the character suitable for use in controlling the switches illustrated in the present system is described in detail in a Patent No. 1,395,977, issued to F. A. Stearn and F. J. Scudder, November 1, 1921.

The subscribers line A, which is one of a plurality of lines terminating in the multiple contacts ofthe line finder 132 on entering the central oiiice, is lirst directed to the main distributing frame MDF. From here it leads to the terminal racks of the intermediate distributing frame IDF. Between the main and intermediate frames the subscribers line is directed through the heat coils 126 which act as a protection against heavy currents. At the intermediate distributing frame, the line is connected and distributed to the desired terminals in the bank of the line iinder switch. Vhen it is desired to make observations on the subscribers line A, a shoe 127 is attached to the line side of the intermediate distributing frame. This shoe is the terminating end of a pair of cord circuits 156-157 and la7- 148. These connecting cords at their other ends terminate, respectively, in the plugs 124 and 123. To complete the association of the line A with the observing position, the plugs 123 and 124: are inserted, respectively, in the jacks of 120 and 121 provided at some convenient location in the vicinity of the distributing frame. From the jacks 120 and 121 the connecting circuit, comprising conductors 102, 103, 106 and 107, leads to the individual apparatus shown in the upper right hand corner of Fig. 3. In this manner the line A is connected through to the operators position and the individual apparatus is now allotted for the sole use of this particular line. In like manner any desired number of other lines similar to line A may be extended to the corresponding individual mechanisms at the observing operators position by mea-ns of other plug and jack connectors. For eX- ainple, a group of forty lines served by the line finder switches may be connected to the observing position at a time whereby the observing operator may take notations of the service being rendered on these lines.

There subscribers lines such as B shown in the upper part of Fig. 1, are served by line switches, the extension of the lines through the main and intermediate frames is substantially t-he same although the method of connecting the line to the observing position differs somewhat. For example, the connection is made at the intermediate distributing frame by means of the cords which terminate in plugs 112, 113 and 114i. The last two cords are attached as illustrated to the proper connecting points on the intermediate distributing frame by shoe 116, while the cord terminating in plug 112 is attached to one terminal of the line relay 118 by a suitable attachment clip. The

Wil. llittltit same is true of lines which terminate in individual switches, namely, that any desired number thereof may be connected to the observing position at a time.

The equipment at the operators desk includes a talking set comprising a receiver 200 (F ig. 2) and a transmitter 229 and a plug and jack switch 201 for rendering the equipment effective. By means. of his talking set the operator may converse with a calling subscriber whose line has been con* nected to his position. Furthermore, there are provided two cycle counters 213 and 225. These devices may consist of any well known mechanism responding to an alternating current and which serves to drive a counting member through one step for each cycle through which the current passes. For operating the cycle counters, there is provided a driving fork 215 which may be adjusted to operate at any desired frequency. The frequency of the driving fork will determine by means of an induction coil 214, the trequency set up in the secondary circuit, and consequently the frequency of the current flowing through the cycle counters. ln an obvious manner the distance through which the movable element of' the cycle counter moves in response to a current oi known frequency may indicate the exactamount of time elapsing trom the instant the counter is started in operation until the operation ceases. The principle of such devices is an old and Well known one for obtaining an accurate measurement of time. The cycle counter per se is not concerned particularly with the present invention and, therefore, it is not considered necessary to describe its operation and mechanism in det-ail. lt is merely one device for obtaining an accurate measurement of the time required for certain operations in the system to take place. Any other time measuring device might be used equally as well provided it gave the required degree oif accuracy. rlhe cycle counter 213, as will be hereinafter described, is used for counting the time elapsing from the instant the subscriber initiates a call until a sender is attached to his line ready to receive impulses. 'lhe cycle counter 225 is used for counting the time between the initiation of the call and the instant when the lirst impulse is sent from the substation.

In addition, the operators desk is equipped with a pen register mechanism consisting of a magnet 203, the armature oi: which carries a pen arranged to engage a moving tape 230 to record the nature of the impulses sent out over the calling line.

Certain other devices, to be described hereinater, are also located at the operators position for making observations ot message registration and coin operations.

The system in general and the appa atns involved therein having been outlined above,

a description will now be given of the detailed operation: 'To this end it is assumed at first that the observing operator wishes to inspect the service beingvrendered on a certain group ot subscribers lines served by line finder switches. To do this, the operator connects each line as hereinbeit'ore eX- plained, to the connecting circuit leading to the observing desk by means of the plug ended connecting cords. Since the identity of each of the several connecting circuits is known, the identity ot the lines to which they are made individual, respectively, is also readily determined.

After having connected up a group of lines on which the service is to be inspected, the observing operator renders his equipment effective for association with any line in the group that calls by completing the plug and jack connection 201. The insertion of these plugs in the jacks extends the conductor 204 over the spring contacts 203 to conductor 231. The conductor 231 leads through the upper contact of relay 232 to ground through the left normal contact of release key 209. The conductor 204 ente-nds over parallel paths to the armature of each of the several relays 300, only one of which is shown. There is a relay 300 individual to each connecting circuit, and consequently, individual to the particular subscribers line associated with the operators position by means ol such connecting circuit. rlhe relay 300 corresponds to the line relay and energizes at the same instant the line relay is operated. lllhenever one of these relays operates, it connects the common conductor 204 through its armature and contact to the winding of an individual relay such as relays 302 and 303 as will presently be described. lilith the apparatus thus in condition to make observations, it is now assumed that the subscriber of line A initiates a call.

Upon removing his receiver from the switchhook, the subscriber of line A closes a circuit from battery through the winding of line relay 152, inner left contact of relay 151, through the intermediate and main distributing frames, conductor 146, over the loop of the subscribers line and returning by way of conductor 145, through the main and intermediate distributing trames to ground at the right contact ot relay 151. The line relay 152 becomes energized in this circuit and in the well known manner causes the line iinder 132 to start in operation, searching tor the subscribers line. The line finder 132 may also be of' the panel power driven type provided with a plurality of sets of brushes arranged to be tripped when operated in the manner described in the patent to J. L. McQuarrie No. 1,177 ,044, patented March 28, 1916. A circuit is also closed at this time in parallel with relay 152 extending from ground at the right armature contact of relay 151 over the circuit above traced to conductor 146, thence over the distributing frames, conductor 148, sleeve of plug 123, sleeve of jack 120, conductor 103, strap 331, armature and back contact of relay 304, strap 332 to battery through the winding of relay 30.0.

At the same instant relay 152 energizes, the relay 300, also included in parallel therewith, attracts its armature. The relay 300 extends the common conductor 204 through its armature and contact, lett contact of relay 305, right winding .of relay 302, makebefore-break contact at the left armature of relay 306, winding of relay 307 to battery. The individual relay 302 and the common relay 307 become operated in this circuit. Relay 302 closes a holding circuit for itself traceable from battery through the left winding and inner left front contact of said relay, winding of relay 306, conductor 210, right Contact of key 209, to ground. Relay 306 energizes in series with the locking circuit of relay 302 and opens the origina-l energizing circuit of relay 302 which included the winding of relay 307. Relay 307, however, remains energized in a circuit from battery through its winding, the make-before-break contact at the left armature of relay 306, thence to ground over conductor 210. Relay 302 closes a circuit from battery through the winding of relay 305, inner left front contact of relay 302 and thence to ground over the conductor 210 as previously traced. Relay 305 operates and creates a second break point in the Ioriginal energizing circuit of relay 302. In parallel to the relay 305, relay 302 completes a circuit or the lamp 301 which is individual to the connecting circuit, and consequently, individual to the calling line A. The lamp 301 illuminates and advises the operator that a call has been initiated on this particular line.

The relay 302, furthermore, extends the circuit 308-309 leading from the operators talking set by way of conductors 102 and 103 through to the subscribers line conductors 145 and 146. In other words, the energization of relay 302 causes the eXtension of the line A to the observing operators telephone equipment, whereby conversation may be held between the subscriber and the operator.

lith relays 300 and 302 operated a circuit is closed from ground, over conductor 204, Contact of relay 300, conductor 310 .outer left contact of relay 302, conductors 311 and 327, left back contact of relay 328, winding of relay 329 to battery. Relay 329 operates and completes a circuit from battery through its winding and the winding of relay 328 in series, right contact oi relay I 329 to ground by way of conductor 210.

Relay 328, however, cannot energize since it is shunted out by the direct circuit to ground traced through the contacts of relays 300 and 302. Relay 329 also cl-oses a lcircuit from ground on conductor 210 over the left armature contact of relay 329, the right armature and back contact of relay 317 to battery through the middle polarizing winding of pulsing relay 242, preparing this relay for later response to dial pulses, by throwing the armature of this relay against its back contact.

The observing equipment at the operators equipment is now connected to the subscribers line A, which connection has taken place instantly in response to the initiation of al call on said line. Should another line in the group associated with the operators position by means of the plug and jack connections originate a call at any time during the connection of the position with the line A, provision is made whereby said second line will be inetlective to cause the connection of the operators position thereto.

`This end is accomplished by rendering all remaining relays 303, etc., which are individual to the other lines in the group inoperative in response to the energization of their corresponding relays 300. F rom inspection of the drawing, it will be seen that the energizing circuit through the right winding of the relay 302 extends from battery through the winding of relay 307 and over the make-before-break contact of relay 306. The conductor 330 leading from the contact vof relay 306 is multipled to the operating winding of all relays 302, 303, etc. Since the relay 302 is energized and the common relay 306 is also operated, the conductor 330 is `opened at the make-beore-break contact of the said latter relay and, hence, no other relay 303, etc., can have its operating circuit closed due to the initiation of a call on the line to which it is individual.

At the instant the relay 307 attracts its armatures, circuits are closed for supplying alternating current to the cycle counters 213 and 225 in order that these devices may commence to count time from the initiation of the call. rlhe circuit for counter 213 may be traced from battery through the tip of jack 211, tip of plug 212, thence through the counter 213, slee-ve of plug 212 sleeve of jack 211, through the right windings of coil 214, conductor 216, lowermost contact of relay 217, conductor 218, outer contact of relay 307, inner right contact of relay 312, conductor 313, sleeve of jack 219, sleeve of plug 220, through the counter 213 tip of plug 220, tip of jack 219, to ground. The circuit for applying current to the othercounter 225 may be traced from battery through the tip of jack 223, tip of plug 224, through the counter 225i, sleeve of plug 224, sleeve of jack 223, thence through the right windings of coil 214, conductor 216, lowermost contact of relay 217, conductor 218, outer contact of relay 307, right contact of relay 314,'co1iductor 315, sleeve of jack 227, sleeve of plug- 226, through the counter 225, tip of plug 226, tip of jack 227 to ground.

As soon as the line finder switch 132 advances its brushes onto the terminals tot the calling subscribers line A, the circuit yis completed in the usual well known manner -for the energization` of the cut-orf relay151. This circuit leads from `a source of battery current `over the neXt to the lowest brush and contact of finder 132, through the winding of relay 151 to ground. A parallel circuit is also closed through the intermediate distributing traine to conducto-r 156, tip: of plug 124, tip of jack 121, conductor 106, through the winding ofrelay 304 to ground.

It may be noted at this point that when the observing equipment vis employed for taking observations on lines which are served by line iinder switches, the 'straps 331 and 332 are closed as indicated and are opened when observations are taken on lines which are served by line switches. These straps are ordinary manual devices adjusted by the operator.

The cut-0E relay 151 opens the circuit of the line relay 152 and also the circuit of relay 300. Relay 304, upon energizing also opens the circuit of relay 300. When relay 300 becomes deenergized, it opens the shunt around the winding of relay 328 and this relay operates in series with relay 329. Relay 328 closes a circuit for the illumination of lamp 333, notifying the observer that the subscribers line has been found.

Then the subscribers line is extended to an idle register sender 135, the sender selector having chosen an idle sender in the manner set forth in the above mentioned patent to F. A. Stearn and F. J. Scudder, No. 1,395,977, issued November 1, 1921, the imp-ulse relay of the selected sender is co-nnected in circuit with the subscribers line in the usual manner and relay 322 of the observing equipment is connected in a circuit therewith. This circuit leads from ground through the winding of relay 322, inner right armature and contact of relay 328, left armature and contact of relay 323, conduct-or 309, inner right armature and contact of relay 302, conductor 103, through the sleeves of jack 120 and plug 123, conductor 14S, terminals of intermediate frame through the next to uppermost brush of the iinder 132, lower left contact of spring 160 and thence to battery at the register sender 135. Relay 322 operates in the circuit traced and completes a circuit from ground over conductor 210, left armature and back contact of relay 314, contact of relay 322, back contact of relay 362, winding of relay 312 to battery. Relay 312 yoperates and completes a circuit from battery through its winding and the winding of relay 362 y in series, left contact of relay 312, conductor 363,1e2t't' normal ',contactof key `209, to ground. Relay 362, however, cannot operate in this circuit since `it shunted :by the circuit closed through the contactjof relay 314. Relay 312 upon 'attraetiijigl its armatures. opens the circuit previouslytraced"over conductor 313 for thev liow ot-jcurrent through vthe cycle counter 21,3. The cycle counter 2,13 thereupon ceases its operation, havingV measured thetiine elapsing between the initiation of the fcalll on the subscribers line, and the instant when an'idleregister sender 135 becomes `attached to such. line ready to receive impulses transmitted from the lsubscribers dial. The'readifngfrom this counter may be taken at any desiredtime lby the observer. Relay 3112 also closes a 4circuitfroin battery through the windingV of; relay 335, outer rig-ht contact `of relay 312 to ground over conductor 210 for aV purpose to be later described.

Immediately thatA the relay 312 operates, which occurs soonl after the extension of the subscribers line to the register sender, a circuit is closed from battery `through the right winding of relay 323, outer right contact of relay 312 to ground over conductor 210. Relay 323 operatesand disconnects the relay 322 from the conductor 309 to prevent the reenergization of said latter relay. Relay 312 also closes acircuitfrom battery through theA lamp 334, outer right contact of relay 312 to the grounded conductor 210. The lamp 334 advises the operator that an idle register sender has been seized.

Relay 312 also closes Ian obvious .circuit for 'rela-y' 317 in parallel with` relay 335 and lamp 334. Relay 317 upon energizing o-pens at its Vright armature and back contact the previously traced polarizing circuit for relay 242 and at its left armature contact establisheslal circuit for relay 325. This latter circuit may be traced from battery through the winding of relay 325, left armature contact of relay 317, conductor 318, inner left armatureand back contact of relay 245, conductor 3119, left armature andback Contact of relay 314 toground on conductor 210. Relay 325 thereupon locks over its armature contact in series with the Winding of relay 314 to ground 'on Vconductor 210. Relay 314 being shunted, however, over the contactofrelay 245V dees not energize atthis time. As scones relay 322 deenergizes, the shunt around the winding of relay 362 is removed and relay'362 energizes in the locking circuit of relay 312. Untilthe irst iinpulse isl dialled the armature of relay 242 is held against-its back contact by a circuit extending from battery over the middle winding' ofi'relay 242, high resistance'elementV 250, the` arniat I' ef and back f contactA of relay 242; thel rig'htariiiatuie' and front con llO tact of relay 317 thence to ground on conductor 210.

It is assumed that the subscriber at substation A has allowed a suificient time for the apparatus at the central oiiice to associate a sender with his line following the initiation of the call. He then manipulates his dial to transmit the first series of impulses corresponding to the wanted designation. Upon the first opening of the line by the impulse sender, a surge of current passes over an inductive branch of the pulsing circuit extending from conductor 148, sleeves of plug 123 and ack 120, conductor 103, inner right armature and contact of relay 302, conductor 309, condenser 252, left winding of polarized pulsing relay 242, right winding of repeating coil 253, conductor 308, outer right armature and contact of relay 302, conductor 102, tips of jack 120 and plug 123 to conductor 147. This surge of current causes relay 242 to attract its armature against its front contract, opening the circuit through its middle winding and closing a circuit extending from battery sleeves of jack 206 and plug 207 pen register magnet winding 208, tips of plug 207 and jack 206, winding of relay 245, armature and contact of relay 242, conductor 254, armature and contact of relay 317 to ground on conductor 210. A circuit is also established from ground on conductor 254 through the armature and front contact of relay 242, right winding of this relay, high resistance element 251, right armature and back contact of relay 243 to battery. -The current now flowing through the right winding of relay 242 locks the armature yagainst its front Contact.

On the next closui'e of the subscribers line circuit current surges through the left winding of polarized relay 242 in the reverse direction throwing the armature thereof against its back contact in which position it is held by current flowing through the middle winding of the relay as previously described. This action of relay 242 is thus repeated for each impulse dialled by the calling subscriber, the magnet 208 energizing each time rela-y 242 attracts its armature against its front contact, and deenergizing each timeJ relay 242 throws its armature against its back contact. Thus the magnet 208 is energized for aI period corresponding to the duration of each line opening and records on the recording t-ape 230 such period by a pen attached to its armature. A record is thus made of each impulse dialled. Relay 245 which operates in series with magnet 208 upon its first energization, opens the circuit previously traced over conductors 318 and 319, thereby removing the shunt from around the winding of relay 314. Relay 314 thereupon operates in series with relay 325 and locks to ground over the conductor 210. The relay 314 at its right armature opens the circuit over conductor 315 for supplying current to the second cycle counter 225. This counter thereupon ceases to operate having accurately measured the time elapsing between the initiation of the call and the instant when the first impulse was transmitted by the subscriber.

Following the last impulse dialled by the subscriber the line loop becomes closed and remains closed during conversation, and relay 242 operates to hold its armature against its back contact. When the subscriber hangs up to release the connection the line loop is again opened and relay 242 operates to move its armature against its front contact. The pen register magnet is again operated and would be held operated until the operator released the connection thus needlessly wasting recording tape unless some provision were made to force the armature of relay 242 against its back contact after an interval longer than would ordinarily measure the duration of a regular dial pulse. This is accomplished by a chain of slow operating relays 246, 244 and 243 which operate in succession, relay 243 upon operating opening the circuit through the right holding winding of relay 242 and closing a circuit at the left contact of relay 243 from ground on conductor 254, through resistance 250 to battery through the middle winding of relay 242. The current flowing through the middle winding of relay 242 forces the armature of this relay against its back contact. The circuits for operating relays 246, 244 and 243 upon a continued energization of relay 245 and magnet 208 are obvious and need not be traced herein.

Assume that the calling line is one on which a coin box is located. In this case coin collect or refund current will be applied to the line at some time during the release of the connection in thc usual manner. It is desirable that the observing operator be notified with respect to the operation of the coin box both as regards the character of the current applied and also the time and duration thereof. For this purpose, the lamps 235 and 236 are provided, one of which signifies that coin collect current is being applied to the line, while the other signifies` that refund current is being sent over the line. Tf the call succeeds, a source of collecting current is applied and in addition to flowing' over the subscribers line, it also flows over the tip conductor' through the intermediate distributing frame, thence as heretofore traced over the conductor 102, outer right contact of relay 302, conductor 308, winding of relay 237, windings of polarized rela-y 238, to ground. Relay 237 operates, but the polarity of the current is such that the polarizedrelay 238 remains inert. Consequently, a circuit is closed from battery through the winding of relay 239, lamp 236, back contact of relay 233, to ground at the front contact` of relay 237. The lamp 236 notities the operator that collecting currentis being applied to the subscribers line. In order that the observers attention may be attracted at this time, the relay 239, on energizing, completes a circuit 'for the buzzer 240. If on the other hand, refund current is applied, its polarity being or' an opposite character, both relays 237 and 233 are operated. In this event, a circuit is closed from battery lthrough the winding of` relay 239, lamp 235, trent contacts ot' relays 233 and 237 to ground, causing the illumination of the lamp 235.

Should the calling subscribers line A be one which is equipped with a message register, it is also desirable that the observer be aware of the fact that the register is operated properly. Atthe time of disconnection, ifthe call proved to be successful, a message register source of current is applied in the usual manner over the lowerrnost brush of the finder switch 132, Contact of the line relay 152, through `the intermediate distributing frame, thence over two parallel branches, one of which leads through the winding of message register 153, back through the. distributing trame, through the left ront contact of the cut-off relay 151 and to ground, and the other of which eX- tends over conductor 157, sleeve of plug 124, sleeve of jack 121, conductor 107, `right contact of relay 305, conductor 316, strap 205, through the winding of relay 223 to ground. Relay 2,23 operates and closes a circuit from battery through the winding of relay 239, lamp 241, to ground at the contact of relay 223. The lamp 241 and the buzzer 240 advise the observer that the message register of Ctlhe calling line has been properly operate After having' completed his observations on the subscribers line A, t-he operator may disconnect the equipment at his desk from said line, in order to render it connectable to some other line in the group, by manipulat ing the release key 209. Upon operating the key 209, ground is removed trom the conductors 210 and 363 thereby permitting relays 302, 306, 307, 305, 323, 329, 362, 312, 317, 314, 325, 335 and 323 to become deener gized. The release of these relays also causes the extinguishment of the lamps 301, 333 and 334.

While provision has been made through the circuits controlled by relays 202 and 232 for preventing the association of the observing circuit with a second calling line if the operator depresses the release key 209 torelease the circuit from a first line at a time when a call has already been initiated on such second line, the detailed operation of such relays will not be described herein.

Reference to my Patent No. 1,504,230 hereinbefore referred to may be had for such description.

When it is desired to associate the equip ment with subscribers lines served by line switches, the connections are made, as illustrated, in the. upper part of Fig. 1. In addition to connecting the different terminals on the intermediate distributing frame with the connecting circ-uit to the operators position, it is necessary in this case to clip conductor 140 to the terminal of line relay 113.

Then the subscriber of line B initiatesa call a. circuit is closed in the usual manner for the line relay 113 and may be traced from battery through the right hand winding of said relay, inner right armature and back contact of cut-off relay 142, thence over the line conductor 137, returning by way ot conductor 136, lett contact of relay 142, to ground. The line` relay 113 operates and initiates the movement of the line switch 123 in the usual manner. A circuit is also established in parallel with relay 113 extending over conductor 140, tips of plug 112 and jack 103, conductor 104 to battery through the winding of relay 300. The stra-ps 331 and 332 are opened for observation of lines of the type and relay 304 is also ineffective.

In response to the energization of relay 300, the same series of operations occur at the operators equipment as described in connection with the line A. Relay 302 is operated, and in turn, starts the energiZat-ion of relays 306, 329, 305l and 307.

When the line switch 123 linds an idle trunk leading to a district selector switch 130, the cut-off relay 142 is operated, thereby disconnecting the line relay 113 and also opening the circuit of relay 300. In response to the deenergization of relay 300, the same operations yoccur at the observers desk as previously explained. Relay 323 is operated and lamp 333 illuminated, notifying the operator that a district switch has been selected. When subsequently, an idle register sender 131 is attached, the relay 322 becomes energized as hereinbetore described, causing the actuation ot relay 312 and the stopping of the cycle counter 213. In response to the lirst impulse sent out by the calling subscribers dial, relay 314 becomes operated and the second cycle counter 225 is arrested. In parallel with the circuit of the cutoff relay 142 a branch leads from the terminal of the intermediate distributing frame, thence over conductor 155, sleeve of plug 114 and jack 110, conductor 107, right contact of relay 305, conductor 316, strap 205, in engagement during the observation of a. line of this character with its lowerinost contact, windings of relays 249 and 243, right armature and back contact of relay 247, to ground at the contact of relay 335.

Relay 243 operates in this circuit but relay 249 being' marginal does not operate at this time. Relay 248 upon energizing' closes a circuit from ground on conductor 363, through the armature and contact of relay 248, the inne-r left armature and back contact of relay 247, the winding of relay 234, to battery through the left winding of relay 247., the resistance of relay 234 is such that relay 247 does not receive suflicient current to operate at this time. Relay 234 upon energizing prepares a circuit for the lamp 241. Relay 234 at its right armature also prepares a circuit through the right winding of relay 247.

If the subscriber-s line has no message register or the 'call is not charged, when the subscriber hangs up his receiver battery is disconnected from the windings of cut-olf relay 142 and relays 248 and 249. Relay 248 upon deenergizing removes the shunt from around the right winding of relay 247, so that relay 247 energizes in a circuit extending from battery through its left winding, the winding of relay 234, the right winding of relay 247, the right armature of relay 234 to ground on conductor 363. Relay 247 at its right contact opens the circuit previously traced through the windings of relays 248 and 249 so that as the subscribers line switch 128 restores, the lower brush thereof cannot |connect full battery potential encountered on the test terminals of idle districts to the windings of relays 248 and 249. This prevents a` false operation of lamp 241 through the false operation of relay 249. Relays 234 and 247 are released as soon as the operator depresses release key 209.

If the subscribers line B is one provided with a message register, metering current is applied at a suitable time over a. circuit leading through the lowermost brush of the line switch 128, thence through the intermediate distributing frame, winding of the message register magnet 154, through the outer right contact and right winding of relay 142 to ground. rlhis metering cur rent also flows over the circuit traced through the windings of relays 248 and 249,l being' of suilicient strength to operate marginal relay 249. The circuit of meter lamp 241 is now completed from battery, winding of relay 239, lamp 241, left contact of relay 234 to ground at the armature end contact of relay 249. Upon the release of the connection relays 248 and 249 deenergizc and relay 247 energizes as before described. The energization of relay 247 in addition to opening the circuit for relays 248 and 249 prepares a circuit for relay 233 extending from battery, winding of relay 233, outer left armature and contact of relay 247, conductor 255 to the` front contact of relay 362.

Should the subscriber on line B make a second call before the operator depresses release key 209, relays 234, 247 and 362 will be at the time energized and when relay 300 energizes in response to a new call, the circuit of relay 233 will be completed from the armature of relay 362, left armature and front contact of relay 328, conductors 327, and 311, outer left contact of relay 302, armature and contact of relay 300 to ground on conductor 204. Relay 233 will thereupon energize short circuiting the winding of relay 234 causing its deenergization. Relay 247 will be maintained energized through the armature and Icontact of relay 233. When relay 300 deenergizes following connection with an idle district, the circuit of relay 233 is opened and relay 233 deenergizes opening the circuit of relay 247. Relay 247 now restores the energizing circuit of relays 249 and 248 so that these relays are in a position to de termine if the second call is properly registered.

All other operations are substantially the same as hereinbefore described in detail in connection with the observation made on the subscribers line A.

l/Vhen the observing equipment is used to make observations on subscribers lines in a step-by-step switching system, the connection of the equipment may be made in substantially the same manner as shown in the lower part of Fig. 1 by use of cord circuits which lead from the main distributing frame to the jacks provided for this purpose. The circuits and apparatus shown in Fig. 3 respond during the extension of the subscribers line in the step-by-step system upon the initiation of a call for controlling the observing devices at the position shown in Fig. 2 in substantially the saine manner as already described in detail. Strap 375 is closed at this time so that relay 312 is operated to stop cycle counter 213 as soon as the time switch plunges and operates relay 304.

In case of observations made on subscribers lines in a step-by-step system, the cycle counter 213.would serve to measure the time from the initiation of the call to the instant when the subscriber-s line had been extended to a first selector switch ready to receive impulses. The cycle counter 225 would be employed for taking a measurement of the time elapsing between the initiation of the call and the instant when the subscriber operates his dial. It will be obvious how the pen register mechanism, the message register signals and the other elements associated with the observers desk are operated to give the same records and indications for a subscribers line in a. stepby-step system as for the lines A or B terminating in an office where power driven switches are involved. In this case how- "lil,

extending connections from said line, im

pulse sending means associated -with said line for automatically controlling said line extending means, an impulse relay, means for inductively associating said relay with said line, and a recording device controlled by said relay for recording impulses transmitted by said impulse sending means.

3. In a telephone system, a line, switching devices, means :tor extending a control circuit from said line to said devices, impulse sending means associated with said line for automatically controlling said switching devices, an impulse relay, means Jfor inductively bridging said relay across said control circuit and a recording device controlled by said relay for recording impulses transmitted over said control circuit from said impulse sending means.

ll. In a telephone system, a plurality ot lines, an operators position, means responsive to the initiation of a call on one of said lines for extending said line, means responsive to the initiation of said call for connecting the operators position to said line, selector switches for further extending said line, impulse means associated with said lines Jfor controlling said switches and means at said operators position indulctively responsive to said impulse means for recording the impulses transmitted thereby.

5. In a telephone system, a line, switching devices, means for extending a control circuit rom said line to said devices, impulse sending means associated with said line for cont-rolling such switching devices, an impulse relay, means for inductively bridging said relay across said control circuit and a recording device controlled by said relay for recording impulses transmitted over said control circuit from said impulse sending means, said relay operating to close the circuit of said recording device upon each opening ot said control circuit and to open the circuit of said recording device upon each subsequent closure of said control circuit.

6. In a telephone system, a line, switching devices, means for extending a control circuit from said line to said device-s, impulse sending means associated with said line for controlling said switching devices, a polarized impulse relay, means for inductively bridging said relay across said control circuit, a recording device controlled by said relay for recording impulses transmitted over said control circuit from said impulse sending means, said relay operating to close the circuitof said reco-rding device upon each opening of said control circuit and to open the circuit of said recording device upon each. subsequent closure ot said control circuit, and locking winding for said relay for holding the armature thereof in either its front or back positions.

7 In a telephone system, a plurality of linesyan operators position, means responsive to the initiation of a call on one of said lines for extending such line, means responsive to the initiation of said call for connecting the operators position to said line, selector switches i'or further extending said line, impulse means lassociated with said ,line for controlling said switches, a polarized impulse relay, means for inductively associating one winding of said relay with said calling line over said connecting means, a

recording device controlled at a front contact ot said relay for recording impulses transmitted by said impulse means, and a polarizing circuit :tor said relay closed upon the initial connection of `said operators position with said line for positioning'the armature ot said relay against its .back contact.

8. In a telephone system, a plurality of lines, an operators position, means responsive to the initiation ot a call on one of said lines for extending such. line, means responsive to the initiation ot said call for connecting the operators position to said line, selector switches for further extending said line, impulse means associated with said line for controlling said switches, a polarized impulse relay, means vfor inductively associating the operating` winding oi' said relay with said calling line over said connecting means, a recording device controlled at a front contact of said relay for recording impulses transmitted by said impulse means, and two polarizing windings for said relay for holding' the armature thereof in either ot the contact-ing positions into which. it is moved by said operating winding.

9. In a telephone system, a plurality ot lines, an operators position, means responsive to the initiation of a call on` one of said lines for lextending' such line, means responsive to the initiation of said call :tor connecting the ofperators position to said line, selector switches for further extending said line, impulse means associated with said line for controlling said switches, a polarized impulse relay, means for inductively associating said relay with said calling line over said connecting means, a recording device controlled at a front Contact of said relay for recording impulses transmitted by said impulse means, a polarizing winding for said relay, and time controlled means for closing a circuit through said polarizing winding to open the circuit of said recording device in case said impulse relay fails to function to that end under the control of the calling line within a predetermined period.

l0. In a telephone system, a line, switching devices, means for extending a control circuit from said line to said devices, impulse sending means associated with said line for contro-lling said devices, a polarized impulse relay, means Jfor inductively bridging said relay across said control circuit, a recording device for recording impulses transmitted over. said control circuit from said impulse sending means, said relay operating to close the circuit of said recording device upon the opening of said control circuit and to open the circuit of said recording device upon the subsequent closure of said control circuit, a polarizing winding 'for said relay, and time controlled means for closing a circuit ythrough said polarizing winding to open the circuit of said recording device in case said control circuit remains open for longer than a predetermined period.

l1. In a telephone system, a plurality of lines, an loperators position, means responsive to the initiation of a call on one of said lines for extending said line, means responsive to the initiation of said call for connecting the operators position to said line, electromagnetic means individual to each of said lines, a. circuit extending through said line extending means for operating said electromagnetic means, a signal at said operators position for indicating the operation of said electromagnetic means, and means for preventing a false operation oi said signal during the restoration of said line extending means.

12. In a telephone system, a plurality of lines, an operators position, means responsive to the initiation of a call on one of said lines for extending such line, means responsive to the initiation of said call for connecting the operators position to said line, electromagnetic means individual to each of said lines, a circuit extending through said line extending means and eiective for operating said electromagnetic means following the restoration of the calling subscribers receiver to the switchhook for releasing the extended connection, a signal at the operators position for indica-ting the operation of said electromagnetic means, and means for preventing a false operation of said signal during the restora. tion of said line extending means.

In witness whereof I hereunto subscribe my name this 7th day of July, A. D., 1923.

JOI-IN W. GOODERHAM.

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