US2360296A - Signaling system - Google Patents

Description

Oct), 1944. B. D.'WILLIS SIGNALING SYSTEM Filed Sept. 11, 1942 4 Sheets-Sheet 3 WW4. Ea 9. 5m t 6% F mm wQSEE H mGE Oct. 10, 1944. B. D. WILLIS 3,356,296

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Patented Oct. 10, 1944 UNITED STATES PATENT OFFICE SIGNALING SYSTEM Application September 11, 1942, Serial No. 457,930 L 17 Claims.

The present invention relates to signaling systems and more particularly to repeater circuits for automatic telephone systems.

In a conventional automatic telephone system including a plurality'of exchanges, repeater circuits are frequently provided in the exchanges in order to terminate the trunks extending therebetween and to insure proper impulse transmission and supervisory control over the trunks. In setting up an interexchange connection in an automatic telephone system of the type noted, subscriber controlled automatic switching apparatus in the calling exchange is operated to seize the repeater circuit terminating one end of an idle trunk extending to the called exchange and to transmit a number of digits thereto. The last-mentioned repeater circuit responds to the digits transmitted thereto and repeats corresponding digits over the trunk to the repeater circuit in the called exchange terminating the other end of the trunk. The last-mentioned repeater circuit responds to the digits transmitted over the trunk and repeats corresponding digits to automatic switching apparatus in the called exchange, thereby selectively to control the operation of the last-mentioned switching apparatus. Each of the digits repeated by the repeater circuit in the calling exchange over the trunk to the repeater circuit in the called exchange is in the form of a series of impulses comprising a number of individual impulses corresponding to the numerical value of the particular digit.

While a repeater arrangement of the type described is entirely satisfactory in operation as long as the associated trunk is in good circuit condition, it fails entirely when the trunk is subjected to certain types of common faults. For example, the presence of a high resistive, capacitive or inductive fault on the trunk effectively blocks the transmission of impulses thereover or so distorts the wave form of the impulses transmitted thereover that the repeater circuit in the called exchange does not faithfully follow the impulses transmitted over the trunk.

Accordingly it is an object of the present invention to provide in a signaling system an improved repeater circuit arrangement, wherein a digit is transmitted from one repeater circuit over a trunk to another repeater circuit in such form that it is not appreciably affected by faulty electrical conditions of the trunk disposed within an extremely wide range.

Another object of the invention is to provide an improved repeater circuit of the type noted, wherein the transmission of a variable digit over the associated trunk is based primarily upon a variable time control of a basic alteration in the electrical circuit condition of the trunk, rather than being based upon a variable number of rapid alterations in the electrical circuit condition of the trunk.

Another object of the invention is to provide an improved repeater circuit of the type noted, wherein a variable digit is transmitted over the associated trunk in the form of a single impulse of variable time duration.

A further object of the invention is to provide in a telephone system a repeater circuit of the type noted which embodies an improved supervisory control arrangement utilizing a simplified circuit network.

A further object of the invention is to provide in a telephone system a repeater circuit arrangement, including an improved repeater, which comprises means for receiving a variable series of impulses and means controlled by the receiving means for transmitting a single impulse of a corresponding variable time duration.

A further object of the invention is to provide in a telephone system a repeater circuit arrangement, including an improved repeater, which comprises means for receiving a single impulse of variable time duration and means controlled by the receiving means for transmitting a corresponding variable series of impulses.

A still further object of the invention is to provide in a telephone system a repeater circuit arrangement, including an improved two-way repeater, which comprises means for receiving a variable series of impulses and for transmitting a single impulse of a corresponding variable time duration and means for receiving a single impulse of variable time duration and for transmitting a corresponding variable series of impulses.

Further features of the invention pertain to the particular arrangement of the circuit elements of the telephone system, whereby the above-outlined and additional operating features are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which Figs. 1 to 4, inclusive, taken together, illustrate diagrammatically one form of a telephone system embodying the present invention; Figs. 1 to 4, inclusive, of the drawings being arranged horizontally end to end in numerical order.

Referring now more particularly to Figs. 1 to 4, inclusive, of the drawings there is illustrated a telephone system comprising two exchanges I and 400 of the automatic type and interconnected by a group of two-way trunks including the trunk I0. Each of the exchanges terminates a plurality of subscriber lines extending to subscriber substations; the exchanges I00 and 400 respectively terminating the subscriber lines IOI and 40I respectively extending to the subscriber substations X and Y. Also each exchange comprises subscriber controlled automatic switching apparatus for setting up the various local and trunk connections. In exchange I00 the switching apparatus comprises a plurality of line switches individual to the subscriber lines terminating thereat, the line switch I02 being individual to the subscriber line IOI, a plurality of selectors including the selector I04, a plurality of connectors including the connector I01, and a group of incoming selectors including the incoming selector I05. Similarly, in exchange 400, the switching apparatus comprises a plurality of line switches individual to the subscriber lines terminating thereat, the line switch 402 being individual to the subscriber line 40I, a plurality of selectors including the selector 404, a plurality of connectors including the connector 401, and a group of incoming selectors including the incoming selector 405. v The opposite ends of each trunk in the group extending between exchange I00 and exchange 400 terminate in repeaters respectively disposed in the exchanges mentioned. For example, one end of the trunk I0 terminates in the repeater IIO disposed in exchange I00 and the other end of the trunk I0 terminates in the repeater 4I0 disposed in exchange 400. In exchange I00 the incoming selectors in the group are individual to the repeaters in the group; for example, the incoming selector I is individual to the repeater I I0 and is normally connected thereto by way of a trunk II5. Similarly, in exchange 400, the incoming selectors in the group are individual to the repeaters in the group; for example, the incoming selector 405 is individual to the repeater 410 and is normally connected thereto by way of a trunk 4 I 5.

In exchange I00 the line switch I02 has access to a trunk I03 extending to the selector I04; the selector I04 has access to a trunk I06 extending to the connector I01 and to a trunk III extending to the repeater IIO; the incoming selector I05 has access to the trunk I06 extending to the connector I01; and the connector I01 has access to a group of subscriber lines including the subscriber line IOI. Similarly, in exchange 400, the line switch 402 has access to a trunk 403 extending to the selector 404; the selector 404 has access to a trunk 406 extending to the connector 401 and to a trunk 4II extending to the repeater M0; the incoming selector 405 has access to the trunk 406 extending to the connector 401; and the connector 401 has access to a group of subscriber lines including the subscriber line 40I.

Preferably, in exchanges I00 and 400, each subscriber substation X, Y etc. comprises conventional substation apparatus including a telephone instrument and a ringer and a calling device or impulse transmitter of the dial type; each of the line switches I02, 402 etc, is of conventional connection and arrangement; each of the selectors I04, 404 etc. and each of the connectors I01, 401 etc. and each of the incoming selectors I05, 405 etc. are of the corresponding conventional Strowger types.

Preferably, in exchanges I00 and 400, the repeaters IIO, 4I0 etc. are identical and are of the connection and arrangement illustrated. More particularly, the repeater IIO comprises a mark switch 200 of the minor type including a bridging wiper 20I provided with an individually associated contact bank, a rotary magnet M202 for driving the wiper 20I step by step in the clockwise directionaway from its normal rotary position, a release magnet M203 for releasing the wiper 20I and for causing it to be returned to its normal rotary position, and a set of switch springs S205 which is actuated when the wiper 20l is driven away from its normal rotary. position. Also the repeater IIO comprise's aa'jsend switch 2I0 of the rotary type includingtwo wipers 2H and 2I2 provided with individually associated contact banks, and a clutch mechanism 2I3 provided with a go magnet M2I4 and a stop magnet M2I5. Preferably, the clutch mechanism 2I3 is of the construction and arrangement of that disclosed in U. S. Patent No. 2,222,131, Bernard D. Willis, granted November 19, 1940; which clutch mechanism comprises a driving shaft, not shown, which is constantly rotated at a fixed predetermined speed, a driven shaft to which the wipers 2H and 2I2 are connected, and a pair of clutch plates carried by the shafts mentioned. Further the repeater IIO comprises a receive mechanism 220 including a commutator 22I associated with a wiper 222, and clutch mechanism 223 provided with a go magnet M224 and a stop magnet M225. Preferably, the clutch mechanism 223 is of the construction and arrangement of that disclosed in the Willis patent mentioned; which clutch mechanism comprises a driving shaft, not shown, which is constantly rotated at a fixed predetermined speed, a driven shaft to which the commutator 22I is connected, and a pair of clutch plates carried by the shafts mentioned. Finally the repeater IIO comprises a transformer 230 including the windings 23I, 232, 233 and 234; a relay group including a series relay RI20, a hold relay RI30, a line relay RI 40, a battery reverse relay RI50, an answer relay RI60, a cutoff relay RI10, a trunk pulse relay RI80, a bridge relay R240, a switch pulse relay R245, an impulse relay R250, two control relays R255 and R260, a polar relay R265, a seizure relay R210, a charge relay R215, a stop relay R280, and a go relay R290; and a control network connected and arranged in a manner morefully described hereinafter.

Similarly, the repeater 4I0 comprises a mark switch 300 of the minor type, including a bridging-wiper 30I provided with an individually associated contact bank, a rotary magnet M302 for driving the wiper 30I step by step in the counterclockwise direction away from its normal rotary position, a release magnet M303 for releasing the wiper 30I and for causing it to be returned to its normal rotary position, and a set of switch springs S305 which is actuated when the wiper 30I is driven away from its normal rotary position. Also the repeater 4I0 comprises a send switch 3I0 of the rotary type including two wipers 3H and 3I2 provided with individually associated contact banks, and clutch mechanism 3I3 provided with a go magnet M3I4 and a stop magnet M3I5. Preferably, the clutch mechanism 3I3 is of the construction and arrangement of that disclosed in the Willis patent mentioned; which clutch mechanism comprises a driving shaft, not shown, which is constantly rotated at a fixed predetermined speed, a driven shaft to which the wipers 3H and 3I2 are connected, and a pair of clutch plates carried by the shafts mentioned. Further the repeater 4l0 comprises a receiver mechanism 320 including a commutator 32| associated with a wiper 322, and clutch mechanism 323 provided with a go magnet M324 and a stop magnet M325. Preferably, the clutch mechanism 323 is of the construction and arrangement of that disclosed in the Willis patent mentioned; which clutch mechanism comprises a driving shaft, not shown, which is constantly rotated at a fixed predetermined speed, a driven shaft to which the commutator SM is connected, and a pair of clutch plates carried by the shafts mentioned. Finally the repeater 4I0 comprises a transformer 330 including the windings 33I, 332, 333 and 334; a relay group including a series relay R420, a hold relay R430, a line relay R440, a battery reverse relay R450, an answer relay R460, a cutoff relay R410, a trunk pulse relay R400, a bridge relay R340, a switch pulse relay R345, an impulse relay R350, two control relays R355 and R360, a polar relay R365, a seizure relay R310, a charge relay R3l5, a stop relay R380, and a go relay R390; and a control network connected and arranged in a manner more fully described hereinafter.

In exchange I00, local calls are set up between the various subscriber substations in accordance with conventional practice; for example, a local call might be set up from the calling subscriber substation X by way of the line switch I02, the selector I04 and the connector I01 to the called subscriber substation; subsequently, this call might be released under the control of the subscriber at the calling subscriber substation X. Similarly, in exchange 400, local calls are set up between the various subscriber substations in accordance with conventional practice; for example, a local call might be set up from the calling subscriber substation Y by way of the line switch 402, the selector 404 and the connector 401 to the called subscriber substation; subsequently, this call might be released under the control of the subscriber at the calling subscriber substation Y.

Considering now the extension of a call in either direction between the exchanges I and 400, it is assumed that a call is to be extended from the calling subscriber substation X in exchange I00 to the called subscriber substation Y in exchange 400 via the trunk I0 extending between the exchanges mentioned. The call is first initiated at the calling subscriber substation X, whereupon the line switch I02 individual to the subscriber line IOI operates automatically in order to select an idle trunk in the associated group, such, for example, as the trunk I03, extending to the selector I04. When the line switch I02 seizes the trunk I03 an obvious loop circuit is completed between the selector I04 and the calling subscriber substation X. The subscriber at the calling subscriber substation X then proceeds to dial the first digit of the directory number of the called subscriber substation Y, whereupon the selector I04 operates in order to select the corresponding group of trunks and then operates automatically to select an idle trunk in this group, such, for example, as the trunk III, extending to the repeater H0, the repeater IIO terminating one end of the trunk I0 in exchange I00 as previously noted.

When the selector I04 seizes the trunk III extending to the repeater IIO a loop circuit is completed between the line relay RI40 in the repeater III) and the calling subscriber substation X; this circuit extending from ground by way of the lower winding of RI40, the contacts I54 and I14, and the winding 233 of the transformer 230 to the line conductor CII3 of the trunk III, and from battery by way of the upper winding of RI40, the contacts I52, Ill and 241 and the winding 23I of the transformer 230 to the line conductor CI I2 of the trunk III, the line conductors CI I2 and CI I3 of the trunk III being connected by way of the selector I04, the trunk I03 and the line switch I 02 to the line conductors of the subscriber line IOI extending to the calling subscriber substation X. When this loop circuit is completed the line relay RI40 operates, thereby to complete, at the contacts I42, an obvious circuit for energizing the winding of the hold relay RI30 in order to cause the latter relay to operate. Upon operating, the hold relay RI30 interrupts, at the contacts I3I and I33, the normally completed connection, including the line conductors CI I6 and CI I! of the trunk II5, between the repeater H0 and the individually associated incoming selector I 05, whereby the incoming selector I05 is cut off of the repeater IIO. Also the hold relay RI30 completes, at the contacts I34, an obvious path for applying ground potential to the control conductor CI I4 of the trunk I I I, thereby to mark the trunk III as busy to the other selectors having access thereto and to retain operated the selector I04 and the line switch I02.

Further the hold relay RI30 interrupts, at the contacts I36, a normally completed path for applying ground potential by way of the lower winding of the polar relay R265, the winding of the control relay R260 and the winding 234 of the transformer 230 to the line conductor CI2 of the trunk I0, and a normally completed mul tiple path for applying ground potential by way of the contacts I6I, the upper winding of the polar relay R265, the winding of the control relay R255, and the winding 232 of the transformer 230 to the line conductor CII of the trunk I0. Finally the hold relay RI 30 completes, at the contacts I35, multiple paths substantially identical to those traced above and including the resistor I 92 and the contacts I8I for applying battery potential to the line conductors CII and CI2 of the trunk I0. More particularly, at this time, the hold relay RI30 completes, at the contacts I35, a series circuit between the repeater I I0 in exchange I00 and the repeater M0 in exchange 400; which series circuit comprises a simplex path including in parallel the line conductors CI I and CI2 of the trunk I0, whereby the upper winding of the polar relay R265 and the winding of the control relay R255 in the repeater IIO are energized in series with the winding of the control relay R355 and the upper winding of the polar relay R365 in the repeater 4| 0, and the lower winding of the polar relay R265 and the winding of the control relay R260 in the repeater IIO are energized in series with the winding of the control relay R360 and the lower winding of the polar relay R365 in the repeater MO. More particularly, the above-traced circuit extends from ground in the repeater M0 by way of the contacts 436 and 46I, the upper winding of R365,

the winding of R355, the winding 332 of the transformer 330, the line conductor CH of the trunk I0, the winding 232 of the transformer 230, the winding of R255, the upper winding of R265, the contacts I 6! and I35, the resistor I92 and the contacts I8I to battery in the repeater H; and from ground in the repeater M0 by way of the contacts 436, the lower winding of R365, the winding of R360, the winding 334 of the transformer 330, the line conductor CI2 of the trunk I0, the winding 234 of the transformer 230, the winding of R260, the lower winding of R265, the contacts I35, the resistor I92 and the contacts I8I to battery in the repeater IIO. When this simplex circuit is completed the control relays R255 and R260 in the repeater I I0 and the control relays R355 and R360 in the repeater 4I0 operate; however, the polar relay R265 in the repeater H0 does not operate; whereas, the polar relay R365 in the repeater 4I0 does operate. The polar relay R265 in the repeater I I0 does not operate due to the fact that the flow of current in the above-traced circuit is from the repeater M0 to the repeater IIO; whereas, the polar relay R365 in the repeater 4I0 does operate due to the fact that the flow of current in the above-traced circuit is from the repeater M0 to the repeater I I0, as noted above.

Upon operating, the polar relay R365 completes, at the contacts 366, an obvious circuit for energizing the stop magnet M325 of the clutch mechanism 323, whereupon the latter magnet operates in order positively to prevent rotation of the commutator 32I at this time. Also the polar relay R365 completes, at the contacts 368, an obvious circuit for energizing the winding of the seizure relay R310, thereby to cause the latter relay to operate. Upon operating, the seizure relay R310 completes, at the contacts 313, an obvious path for applying ground potential to the control conductor C4I4 of the trunk 4 extending to the repeater 4I0, thereby to mark the trunk 4| I as busy to the selectors 404 etc. having access thereto. Also the seizure relay R310 completes, at the contacts 312, an obvious circuit for energizing the winding of the cutoff relay R410 in multiple with the upper winding of the answer relay R400, whereby the cutoff relay R410 operates. However, the answer relay R460 does not operate as it is of the polarized type. Upon operating, the cutoff relay R410 interrupts, at the contacts MI and 414, an obvious normally completed path for connecting the upper and lower windings of the line relay R440 to the line conductors C4I2 and C4I3 of the trunk 4H; and completes, at the contacts 412 and 413, a bridge connection including the lower winding of the answer relay R460 between the line conductors of the trunk 4I5 extending to the incoming selector 405. The above-mentioned bridge connection extends from the line conductor C4I6 of the trunk M5 by way of the contacts 43I, the winding 33! of the transformer 330, the contacts 341 and 412, the resistor 49I, the lower winding of R460, the contacts 413, the winding 333 of the transformer 330 and the contacts 433 to the line conductor C4I1 of the trunk 4I5. When this bridge path is completed between the line conductors of the trunk M5 the lower winding of the answer relay R460 is energized; however, the latter relay does not operate at this time as it is of the polarized type, as previously noted. Also when this bridge path is completed between the line conductors of the trunk M5 the incoming selector 405 is conditioned to be responsive to impulses transmitted thereto.

The subscriber at the calling subscriber substation X then proceeds to dial the second digit of the directory number of the called subscriber substation Y, whereby the line relay RI40 in the repeater Il0 follows the digit mentioned in an obvious manner. Each time the line relay RI40 restores and then reoperates it completes and then interrupts, at the contacts I4I, an obvious circuit, including the contacts I32, for energizing the winding of the series relay RI20 in series with the rotary magnet M202; whereupon the series relay RI20 operates and the rotary magnet M202 operates and restores, thereby to drive the wiper 20I of the mark switch 200 one step in the clockwise direction. Also each time the line relay RI40 restores and then reoperates it interrupts and then completes, at the contacts I42, the previously mentioned circuit for energizing the winding of the hold relay RI30. Accordingly the hold relay RI30 and the series relay RI20 remain operated during impulsing as both of the relays mentioned are of the slow-to-release type; and the wiper 20I of the mark switch 200 is driven a number of steps in the clockwise direction away from its normal rotary position corresponding to the second digit, in an obvious manner? -When the wiper 20I of the mark switch 2 00'is driven one step in the clockwise direction away from its normal rotary position the set of switch springs S205 is operated, thereby to complete an obvious path, including the contacts IZI, for applying ground potential to the wiper 29!. The application of ground potential to the wiper 20I of the mark switch 200 completes an obvious circuit, including the contacts 292 and 28I, for energizing the winding of the go relay R290 in view of the fact that the wiper 20] engages the first contact in the associated contact bank. When thus energized the go relay R290 operates to complete, at the contacts 29L an obvious holding circuit, including the contacts 28 I, for energizing the winding thereof; and to complete, at the contacts 294, a path for applying ground potential to the first contact in the contact bank associated with the wiper 2II of the send switch 2I0. The lastmentioned path extends from ground by way of the set of switch springs 8205, the contacts Hi, the wiper 20I of the mark switch 200 and the engaged first contact in the associated contact bank, and the contacts 294 to the first contact in the contact bank engaged by the wiper 2 of the send switch 2I0. This application of ground potential to the wiper 2II of the send switch 2I0 completes an obvious circuit for energizing the winding of the trunk pulse relay RI80, thereby to cause the latter relay to operate.

Upon operating, the trunk pulse relay RI interrupts, at the contacts IBI, the previously traced simplex circuit for energizing in series the upper winding of the polar relay R265, the winding of the control relay R255, the winding of the control relay R355 and the upper winding of the polar relay R365, and for energizing in series the lower winding of the polar relay R265, the winding of the control relay R260, the winding of the control relay R360 and the lower winding of the polar relay R365. When this simplex circuit is thus interrupted the control relays R255 and R260, as well as the control relays R355 and R360, restore without effect at this time; the polar relay R265 remains restored; and the polar relay R365 restores, for a purpose more fully explained hereinafter.

Also when the go relay R290 operates it completes, at the contacts 293, an obvious circuit for energizing the go magnet M2 M of the clutch 2l3, whereupon the latter magnet operates in order to engage the pair of clutch plates; whereby the shaft of the send switch 2l0, carrying the wipers 2H and 2l2 thereof, is constantly rotated in the clockwise direction at the fixed predetermined speed.

As previously noted, the line relay R140 follows the second digit dialed at the calling subscriber substation X, whereby, at the conclusion of the second digit, the rotary magnet M202 has been energized a corresponding number of times and the wiper 20| of the mark switch 200 bridges a corresponding number of the contacts in the associated contact bank. For example, in the event the second digit is 5, the wiper 20! of the mark switch 200 bridges the first five contacts in the associated contact bank, whereby ground potential is applied to each of the first five contacts mentioned. As the wiper 2H of the send switch 2") is rotated in the clockwise direction it first engages the second contact and then disengages the first contact in the associated contact bank, thereby to complete an obvious alternative circuit substantially identical to that previously traced for energizing the winding of the trunk pulse relay Rl80. Hence, in the present example, the wiper 2]! of the send switch 210, as it is rotated in the clockwise direction, successively makes and then interrupts five obvious alternative circuits for energizing the winding of the trunk pulse relay RI 80, whereby the last alternative circuit for energizing the winding of the trunk pulse relay RIBO is interrupted only when the wiper 20I engages the sixth contact and disengages the fifth contact in the associated contact bank, thereby to cause the trunk pulse relay RI 80 to restore. Upon restoring, the trunk pulse relay R|80 recompletes, at the contacts I81, the previously traced simplex circuit for energizing the upper and lower windings of the polar relays R265 and R365 and for energizing the windings of the control relays R255, R260, R355 and R360, in the manner previously explained. When this simplex circuit is again recompleted the polar relay R265 remains in its restored position; the polar relay R365 reoperates for a purpose more fully explained hereinafter; and the control relays R255, R260, R355 and R360 reoperate without effect at this time.

At the conclusion of the second digit dialed at the calling subscriber substation X the line relay Rl40 is retained in its operated position, thereby to retain interrupted, at the contacts l ll, the previously traced series circuit for energizing the winding of the series relay Rl20 and the rotary magnet M202 of the mark switch 200. Shortly thereafter the series relay R|20 restores, the latter relay being of the slow-to-release type as previously noted. Upon restoring, the series relay R|20 interrupts, at the contacts I2l, the previously traced path for applying ground potential to the wiper 20! of the mark switch 200, thereby to interrupt a further point in the previously traced circuit for energizing the winding of the trunk pulse relay RIBO. Also, upon restoring, the series relay Rl20 completes, at the contacts I22, a circuit, including the set of switch springsS205 and the contacts I82, for energizing the release magnet M203, thereby to cause the latter mag net to operate and release the wiper 20! of the mark switch 200; whereupon the wiper 20! is returned in the counterclockwise direction to its normal rotary position. Also, upon operating, the release magnet M203 completes, at the contacts 204, an obvious holding circuit, including the set of switch springs S205, for energizing the magnet M203. When the mark switch 200 is thus released the set of switch springs S205 is actuated, thereby to interrupt the above-traced holding circuit for energizing the release magnet M203 of the mark switch 200, whereby the latter magnet restores.

Further operation of the send switch 2H] occurs at this time without effect until the wiper 2l2 thereof engages and then disengages the tenth contact in the associated contact bank. When the wiper 2I2 of the send switch 2l0 engages the tenth contact in the associated contact bank an obvious circuit for energizing the winding of the charge relay R215 is completed, thereby to cause the latter relay to operate. Upon operating, the charge relay R215 completes, at the contacts 216, an obvious circuit for charging the condenser 231. When the wiper 2l2 of the send switch 210 is driven to disengage the tenth contact in the associated contact bank and back into its normal rotary position, the above-traced circuit for energizing the winding of the charge relay R215 is interrupted, thereby to cause the latter relay to restore. Upon restoring, the charge relay R215 interrupts, at the contacts 216, the previously mentioned circuit for charging the condenser 231; and completes, at the contacts 211, an obvious circuit for discharging the condenser 231 in series through the winding of the stop relay R280. When the condenser 231 is thus discharged through the winding of the stop relay R280 the latter relay is momentarily energized.

' Hence the stop relay R280 operates and then restores. Upon operating, the stop relay R280 interrupts, at the contacts 28 l the previously traced holding circuit for energizing the winding of the go relay R290, thereby to cause the latter relay to restore. Upon restoring, the go relay R290 interrupts, at the contacts 293, the previously mentioned circuit for energizing the go magnet M2 [4 of the clutch 2I3. Also, upon operating, the stop relay R280 completes, at the contacts 282, an obvious circuit for energizing the stop magnet M2 [5 of the clutch 2 l3. When the go magnet M2i l of the clutch 213 is deenergized and the stop magnet M2l5 thereof is energized the clutch plates thereof are disengaged, whereby further rotation of the shaft of the send switch 2l0 is arrested at a time when the wipers 2H and 212 thereof occupy their normal rotary positions. At this time the wiper 2 of the send switch 210 engages the first contact in the associated contact bank and the wiper 2l2 of the send switch 2l0 disengages the tenth contact in the associated contact bank. Upon restoring, the stop relay R280 interrupts, at the contacts 282, the previously mentioned circuit for energizing the stop magnet M2l5 of the clutch 213, thereby to cause the latter magnet to restore without effect at thistime. Accordingly, at this time, the apparatus incorporated in the repeater l I0 occupie the seized position thereof, this position being the same as that which it occupied prior to the reception of the second digit 5 dialed at the calling subscriber substation X.

In view of the foregoing explanation of the mode of operation of the repeater H0, it will be understood that the mark switch 200 is operative to register the digit dialed at the calling subscriber substation and to initiate operation of the send switch 2 l 0, whereupon the trunk pulse relay Rl operates. Operation of the send switch'2l0 is continued at a constant predetermined speed for a time interval corresponding to the digit registered in the mark switch 200 in order to retain the trunk pulse relay RI80 in its operated position during this time interval mentioned. At the conclusion of this time interval mentioned the wiper 2II of the send switch 2 I disengages the last marked contact in the associated contact bank, thereby to effect the restoration of the trunk pulse relay RI80. Also at this time the series relay RI20 restores, which is shortly following the conclusion of the digit, in order to effect the release of the mark switch 200. The send switch 2 I 0 is then further operated back into its normal position, whereupon further operation thereof is arrested. It will be understood that operation of the send switch 2I0 is initiated immediately upon operation of the mark switch 200; that the effective operation of the send switch 2I0, to retain operated the trunk pulse relay RI80, is completed very shortly following the conclusion of the digit received by the repeater I I0; and that this effective operation of the send switch 2I0 is completed shortly prior to the restoration of the series relay RI20, the latter relay restoring shortly followin the reception of the digit mentioned. Hence it will be understood that the repeater IIO is operative to register any digit dialed at the calling subscriber substation X and to effect operation of the trunk pulse relay RI80, in response to this digit received for a time interval corresponding to the digit mentioned. More particularly, the trunk pulse relay RI80 is retained operated a variable time interval precisely corresponding to the variable number of impulses in the digit received by the repeater I I0. Further it will be understood that the operation of the trunk pulse relay RI80 for the variable time interval mentioned retains interrupted for this variable time interval the previously traced simplex circuit extending between the repeater H0 and the repeater M0; and then recompletes, at the conclusion of the time interval mentioned, the previously traced simplex circuit between the repeater H0 and the repeater 4I0. Accordingly, it will be understood that the repeater H0 is effective to register any variable digit and to transmit over the trunk I0 to the repeater 4 I 0 a single impulse of a corresponding variable time duration. For example, the repeater H0 is efiective to register the digit 4, 5 or 6 and to transmit over the trunk II] to the repeate MD a single impulse of corresponding 4, 5 or 6 unit time intervals of duration.

Continue now with the operation of the repeater M0 in response to the restoration of. the polar relay R365, at the beginning of the single impulse received thereby when the previously traced simplex circuit including the trunk I0 is interrupted. Upon restoring, the polar relay R365 interrupts, at the contacts 368, th previously mentioned circuit for energizing the winding of the seizure relay R310; however, the latter relay does not restore during the reception of any impulse as it is of the dashpot type. Also, upon restoring, the polar relay R365 interrupts, at the contacts 366, the previously mentioned circuit for energizing the stop magnet M325 of the clutch 323, and completes, at the contacts 361, an ob vious circuit, including the contacts 31I, for energizing the go magnet M324 of the clutch 323. When the stop magnet M325 is deenergized and the go magnet M324 is energized the clutch plates are engaged, whereby the shaft and the commutator 32I carried thereby are rotated in the counterclockwise direction continuously at the predetermined speed previously mentioned. As

the commutator 32I is rotated at the predetermined speed in the counterclockwise direction, the conductive and insulating segments thereof alternately engage the associated Wiper 322, thereby to complete and then to interrupt repeatedly an obvious circuit for energizing the winding of the impulse relay R350; whereby the latter relay operates and restores at a fixed rate corresponding to the predetermined speed of rotation of the commutator 32| in the counterclockwise direction. Each time th impulse relay R350 operates it interrupts, at the contacts 352, an obvious circuit for charging the condenser 333; and completes, at the contacts 35I, an obvious circuit for discharging the condenser 336 in series through the winding of the switch pulse relay R345, whereby the later relay operates and then restores. Each time the impulse relay R350 restores it interrupts, at the contacts 35I, the previously mentioned circuit for discharging the condenser 339 in series through the winding of the switch pulse relay R345; and recompletes,.at

the contacts 352, the previously mentionedv cir cuit for charging the condenser 339. Accordingly the switch pulse relay R345 follows the impulse relay R350. Upon the first operation of the switch pulse relay R345 it completes, at the contacts 346, an obvious circuit for energizing the winding of the bridge relay R340, thereby to cause the latter relay to operate. Also upon the first operation of the switch pulse relay R345 it interrupts, at the contacts 341, the previously traced path for connecting the lower winding of the answer relay R460 across the line conductors of the trunk 4I5 extending to the incoming selector 405. Upon operating, the bridge relay R340 completes, at the contacts 34 I, an obvious path, including the contacts 412 and 413 and the resistor 49I, for short-circuiting the winding 333 of the transformer 330 in series with the lower winding of the answer relay R460. Upon the first restoration of the switch pulse relay R345 it interrupts, at the contacts 346, the previously mentioned circuit for energizing the winding of the bridge relay R340; however, the latter relay does not restore during impulsing as it is of the slow-torelease type. Also upon the first restoration of the switch pulse relay R345 it completes, at the contacts 341, a bridge across the line conductors of the trunk 4I5 extending to the incoming selector 405- The above-mentioned bridge extends from the line conductor C4I1 of the trunk M5 by way of the contacts 433, C4I3, the contacts 34I and 341, the winding 33I of the transformer 330 and the contacts 43I to the line conductor CNS of the trunk 4I5- Accordingly the switch pulse relay R345 repeats impulses at the contacts 341 over the trunk M5 to the incoming selector 405, thereby to cause operation of the lastmentioned selector in accordance with conventional practice.

At the conclusion of the single impulse transmitted over the trunk I0 to the repeater M0, the previously traced simplex circuit between the repeater H0 and the repeater M0 is recompleted, thereby to cause reoperation of the polar relay R365, as previously noted. Upon reoperating, the polar relay R365 recompletes, at the contacts 368, the previously mentioned circuit for energizing the winding of the seizure relay R310, whereby the latter relay is retained in its operated position continuously, as previously explained. Also the polar relay R365 interrupts, at the contacts 361, the previously traced circuit for energizing the go magnet M324 of the clutch 323; and completes, at the contacts 366, the previously mentioned circuit for energizing the stop magnet M325 in the clutch 323. When the go magnet M324 is deenergized and the stop magnet M325 is energized the pair of clutch plates are disengaged, whereby further rotation of the commutator 321 in the counterclockwise direction is arrested, thereby to prevent further intermittent operation of the impulse relay R350. At this point it is noted that, when operation of the commutator 321 is arrested, the associated wiper 322 may engage either a conductive or an insulating segment thereof, whereby the impulse relay R350 may be retained either in its operated or its restored position. However, regardless of whether the impulse relay R350 is retained in its operated position or its restored position, the switch pulse relay R345 is restored in order to effect the restoration of the bridge relay R340 shortly thereafter, the bridge relay R340 being of the slow-to-release type. Upon restoring, the bridge relay R340 interrupts, at the contacts 341, the previously traced path for short-circuiting the winding 333 of the transformer 330 in series with the lower winding of the answer relay R460, whereupon the previously traced circuit for connecting the lower winding of the answer relay R460 across the line conductors of the trunk 415 extending to the incoming selector 405 is recompleted. Accordingly, at this time, the apparatus incorporated in the repeater 410 occupies the seized position thereof, this position being the same as that which it occupied prior to the reception of the single impulse over the trunk 10 which was transmitted by the repeater 1 10.

In view of the foregoing explanation of the mode of operation of the repeater 410, it will be understood that the polar relay R365 is restored for a variable time interval corresponding to the variable time duration of the single impulse received over the trunk 10; and then the polar relay R335 reoperates. During the time interval while the polar relay R365 occupies its restored position, the commutator 321 is continu ously rotated at the fixed predetermined speed in the counterclockwise direction; whereby the impulse relay R350 is operated and restored a corresponding number of times in order to effect a corresponding number of operations and restorations of the switch pulse relay R345. Hence the number of intermittent operations of the switch pulse relay R345, to transmit impulses over the trunk 415 extending to the incoming selector 405, is proportional to the time interval during which the commutator 321 is continuously rotated in the counterclockwise direction, which time interval is proportional to the time duration of the single impulse received over the trunk 10. More particularly, the speed of rotation of the commutator 321 in the counterclockwise direction is so correlated with respect to the time duration of the single impulse received over the trunk 10 that the switch pulse relay R345 is operated to transmit a number of impulses over the trunk 415 extending to the incoming selector 405 corresponding to the number of unit time intervals of the duration of the single impulse received over the trunk 10. Accordingly the repeater 410 is operative to receive a single impulse of variable time duration over the trunk 10 and to repeat a number of impulses over the trunk 415 corresponding to the time duration of the single impulse mentioned. For example, the repeater 410 is operative to receive the single impulse of 4, 5 or 6 unit time itervals of duration and to transmit a series of impulses over the trunk 415, including the corresponding 4, 5 or 6 impulses.

The incoming selector 405 responds to the second digit dialed at the calling subscriber substation X to select a corresponding group of trunks and then operates automatically to seize an idle trunk in the selected group, such, for example, as the trunk 406, extending to the connector 401. When the trunk 406 extending to the connector 401 is seized by the incoming selector 405 the connector 401 is rendered responsive to impulses transmitted thereto in accordance with conventional practice.

The subscriber at the calling subscriber substation X then proceeds to dial the third digit of the directory number of the called subscriber substation Y. The repeater first registers the third digit received over the trunk 111 and transmits a single impulse over the trunk 10 in the manner previously explained, the single impulse transmitted over the trunk 10 comprising a number of unit time intervals of duration corresponding to the number of impulses of the third digit received over the trunk 111. The repeater 410 receives the single impulse over the trunk 10 and transmits a series of impulses over the trunk 415, the number of impulses in the series transmitted over the trunk 415 corresponding to the number of unit time intervals of duration of the single impulse received over the trunk 10, and consequently to the third digit dialed at the calling subscriber substation X. The subscriber at the calling subscriber substation X then proceeds to dial the fourth digit of the directory number of the called subscriber substation Y, whereby the repeaters 110 and 410 operate in the manner described above. particularly, the third and fourth digits of the directory number of the called subscriber substation Y are repeated by the repeater 410 over the trunk 415, the incoming selector 405 and the trunk 406 to the connector 401, whereby the connector 40'! operates in order to select the subscriber line 401 extending to the called subscriber substation Y in accordance with conventional practice.

When the connector 40'! seizes the subscriber line 401 extending to the called subscriber substation Y the idle or busy condition thereof is tested, whereby ringing current is projected thereover from the connector 40! and ring-back tone current is returned from the connector 40'! over the trunk 415 to the repeater 410, all in the event the subscriber line 401 is idle. On the other hand, in th event the subscriber line 401 is busy, busy tone current is returned from the connector 401 over the trunk 415 to the repeater 410. The ring-back tone current or the busy tone current returned over the trunk 415 traverses the windings 331 and 333 of the transformer 330 included in the previously traced circuit, whereby a corresponding tone voltage is induced in the windings 332 and 334 of the transformer 330 in order to cause a corresponding tone current to be returned over the trunk 10. The tone current returned over the trunk 10 traverses the windings 232 and 234 of the transformer 230 in order to induce a corresponding tone voltage in the windings 231 and 233 of the transformer 230, whereby a corresponding tone current is returned over the subscriber line 101 to the calling subscriber substation X. In the event ring-back tone current is returned to the calling subscriber substation X, it indicates to the subscriber thereat More that the called subscriber substation Y is being rung and the subscriber at the calling subscriber substation X waits for the subscriber at th called subscriber substation Y to answer the call. On the other hand, in the event busy tone current is returned to the calling subscriber substation X, it indicates to the subscriber thereat that the desired connection may not be had immediately due to the busy condition of the called subscriber substation Y; whereupon the subscriber at the calling subscriber substation X replaces the receiver of the telephone instrument thercat upon its associated switchhook, thereby to effect the release of the switching apparatus involved in the incompleted connection, in a manner more fully explained hereinafter.

Assuming that the called subscriber substation Y is idle at this time, when the subscriber thereat answers the call the connector 401 operates in order to cause current to be reversed over the trunk 4I5 extending to the repeater 4I0, whereby the lower winding of the answer relay R460 is energized in the opposite direction. When the lower winding of the answer relay R460 is energized in the direction mentioned the latter relay operates as it is of the polarized type and the upper winding thereof is directly energized at this time. Upon operating, the answer relay R460 interrupts, at the contacts 46I, a point in the previously traced simplex circuit for energizing in series the upper winding of the polar relay R365, th winding of the control relay R355, the winding of the control relay R255 and the upper winding of the polar relay R265; however, the previously traced circuit for energizing the lower winding of the polar relay R365, the winding of the control relay R360, the winding of the control relay R2 60 and the lower winding of the polar relay R265 is retained completed. Accordingly, at this time, the control relays R355 and R255 restore; the control relays R360 and R260 are retained in their operated positions; the polar relay R365 is retained in its operated position; and the polar relay R265 is retained in its restored position. Upon restoring, the control relay R355 completes, at the contacts 356, an obvious circuit for energizing the winding of the battery reverse relay R450, thereby to cause the latter relay to operate. The operation of the battery reverse relay R450 is without elfect at this time in view of the operated position of the cutoff relay R470. Upon restoring, the control relay R255 completes, at the contacts 256, an obvious circuit for energizing the winding of the battery reverse relay RI50, thereby to cause the latter relay to operate. Upon operating, the battery reverse relay RI 50 completes, at the contacts I5I and I53, a circuit substantially identical to that previously traced for, energizing the upper and lower windings of the line relay RI40; and interrupts, at the contacts I52 and I54, the previously traced original circuit for energizing in series the upper and lower windings of the line relay RI 40; whereby the direction of battery current feed over the trunk III to the selector I04 is reversed. This reversal of battery current feed over the trunk III to the selector I04 and consequently over the trunk I03, the line switch I02 and the subscriber lin I0l extending to the calling subscriber substation X may be utilized for supervisory purposes, meter control in the line switch I02, etc., all in accordance with conventional practice.

At this time an established connection is completed between the calling subscriber substation X in exchange I00 and the called subscriber substation Y in exchange 400. More pa ticularly, the previously traced loop circuit is completed between the calling subscriber substation X and the line relay Rl40 in the repeater IIO, which loop circuit includes the windings 23I and 233 of the transformer 230; the windings 232 and 234 of the transformer 230 are operatively connected by way of the trunk I0 to the windings 332 and 334 of the transformer 330 in the repeater M0; the windings 33I and 333 of the transformer 330 are included in the previously traced loop circuit extending between the lower winding of the answer relay R460 and the connector 401, the last-mentioned loop circuit including the trunk M5, the incoming selector 405 and the trunk 4063; and'an obvious loop circuit is completed between the connector 401 by way of the subscriber line 40I to the called subscriber substation Y. Accordingly the conversation between the calling subscriber substation X in exchange I00 and the called subscriber substation Y in exchange 400 proceeds.

The release of this established connection is assumed to be under the control of the subscriber at the calling subscriber substation X in exchange I00 and is effected when the subscriber thereat replaces the receiver of the telephone instrument at the calling subscriber substation X upon its associated switchhook in order to interrupt the previously traced loop circuit for energizing in series the upper and lower windings of the line relay RI40 in the repeater IIO. When the loop circuit mentioned is interrupted the line relay RI40 restores, thereby to interrupt, at the contacts I42, the previously mentioned circuit for energizing the winding of the hold relay Rl30; whereupon the latter relay restores shortly thereafter, the hold relay RI30 being of the slow-torelease type. Also, upon restoring, the line relay RI40 completes, at the contacts H, the previously traced circuit for energizing the winding of the series relay RI20 in series with the rotary magnet M202 of the mark switch 200. The rotary magnet M202 operates, thereby to drive the wiper 20I of the mark switch 200 one step in the clockwise direction, in the manner previously explained; and the series relay RI20 operates in order to complete, at the contacts I2I, the previously traced path for applying ground potential to the wiper 20I of the mark switch 200, whereby the go relay R2 90 operates in order to effect operation of the send switch 210 in the manner previously explained. Also the go relay R290 completes, at the contacts 294, the previously traced circuit for energizing the winding of the trunk pulse relay RI80, thereby to cause the latter relay to operate. Upon operating, the trunk pulse relay RI interrupts, at the contacts I8I, the previously traced series circuit for energizing the lower winding of the polar relay R265, the winding of the control relay R260, the winding of the control relay R360 and the lower winding of the polar relay R365; whereby the control relays R260 and R360 and the polar relay R365 restore. Upon restoring, the control relay R260 interrupts, at the contacts 26I, the previously traced circuit for energizing the winding of the battery reverse relay RI50, thereby to cause the latter relay to restore. Upon restoring, the control relay R360 interrupts, at the contacts 36I, the previously traced circuit for energizing the winding of the battery reverse relay R450, thereby to cause the latter relay to restore.

Operation of the send switch 2I0 proceeds in the manner previously explained and when the wiper 2 thereof disengages the first contact in the associated contact bank the previously traced circuit for energizing the winding of the trunk pulse relay RI80 is interrupted, whereupon the latter relay restores. Upon restoring, the trunk pulse relay RI80 recompletes, at the contacts I8 I, the previously traced series circuit for energizing the lower winding of the polar relay R265, the Winding of the control relay R260, the winding of the control relay R360, and the lower winding of the polar relay R365, whereby the control relays R260 and R360 and the polar relay R365 reoperate. Upon operating, the control relay R260 completes, at the contacts 26 I, the previously traced circuit for energizing the winding of the battery reverse relay RI50, thereby to cause the latter relay to operate. Upon operating the control relay R360 completes, at the contacts 36I, the previously traced circuit for energizing the Winding of the battery reverse relay R450, thereby to cause the latter relay to operate.

When the hold relay RI30 restores, as previously explained, shortly following the release op eration performed at the calling subscriber substation X it interrupts, at the contacts I32, the previously traced circuit for energizing the winding of the series relay RI in series with the rotary magnet M202, whereupon the series relay RI20 restores shortly thereafter, the series relay RI20 being of the slow-to-release type. Further the hold relay RI recompletes, at the contacts I3I and I33, the connection between the line conductors CI I2 and CI I3 of the trunk III and the line conductors CI I6 and CI I7 of the trunk H5, the trunk II5 extending to the incoming selector I05. Further the hold relay RI30 interrupts, at the contacts I34, the previously traced path for applying ground potential to the control conductor of the trunk I I I, thereby to effect the release of the selector I04 and the line switch I 02. At this time the trunk III extending to the repeater I I0 is marked as idle to the selectors having access thereto; the trunk I03 extending to the selector I04 is marked as idle to the line switches having access thereto; and the subscriber line IOI extending to the calling subscriber substation X is marked as idle to the connectors having access thereto.

Cperation of the send switch 2E0 proceeds in the manner previously explained, whereby the wipers 2H and 2I2 thereof are returned to their normal rotary positions; the charge relay R275 operates and restores, thereby to effect operation and restoration of the stop relay R280, as previously explained. Upon operating, the stop relay R280 interrupts, at the contacts 28I, the previously traced holding circuit for energizing the winding of the go relay R290, thereby to cause the latter relay to restore. Upon restoring, the go relay R290 interrupts, at the contacts 293, the previously mentioned circuit for energizing the go magnet M2I4 of the clutch 2I3; and, upon operating, the stop relay R280 completes, at the contacts 262, the previously mentioned circuit for energizing the stop magnet M2I5 of the clutch 2I3. Upon restoring, the stop relay R280 interrupts, at the contacts 282, the previously mentioned circuit for energizing the stop magnet M2I5 of the clutch 2I3, whereby the send switch 2I0 is completely released.

Further, upon restoring, the hold relay RI30 interrupts, at the contacts I35, the previously traced circuit for energizing in series the lower winding of the polar relay R265, the winding of the control relay R260, the winding of the control relay R360 and the lower winding of the polar relay R365, whereby the control relays R260 and R360 and the polar relay R365 restore. Upon restoring, the control relay R260 interrupts, at the contacts 26I, the previously mentioned circuit for energizing the winding of the battery reverse relay RI50, thereby to cause the latter relay to restore. At this time the repeater III] is completely released and available for further use.

Considering now the release of the repeater 4 I 0, the first time the polar relay R365 restored it interrupted, at the contacts 366, the previously mentioned circuit for energizing the stop magnot M325 of the clutch 323 and completed, at the contacts 367, the previously traced circuit for energizing the go magnet M325 of the clutch 323, whereby the commutator 32I was rotated in the counterclockwise direction. Subsequently, when the polar relay R365 reoperated it recompleted, at the contacts 366, the previously mentioned circuit for energizing the stop magnet M325 of the clutch 323 and interrupted, at the contacts 367, the previously traced circuit for energizing the go magnet M324 of the clutch 323, whereby further rotation of the commutator 32I was arrested. This rotation of the commutator 32I caused one operation and restoration of the impulse relay R350 and consequently one operation and restoration of the switch pulse relay R345, whereby the bridge relay R340 was operated. Also the operation and subsequent restoration of the switch pulse relay R345 caused one impulse to be transmitted over the trunk M5 to the connector 407 without efiect at this time.

When the polar relay R365 again restored it again initiated rotation of the commutator 32I, whereby the impulse relay R350 and the switch pulse relay R345 were again operated intermittently and the bridge relay R340 was operated. However, at this time, the polar relay R365 remains restored and after a predetermined time interval the seizure relay R370 restores, the latter relay being of the dash-pot type and having a slow-to-release characteristic. Upon restoring, the seizure relay R370 interrupts, at the contacts 37I, the previously traced circuit for energizing the go magnet M324 of the clutch 323, whereby further rotation of the commutator 32I in the counterclockwise direction is arrested in order to effect restoration of the impulse relay R350 and the switch pulse relay R345 and restoration of the bridge relay R340 shortly thereafter, the bridge relay R340 being of the slow-to-release type. Also, upon restoring, the seizure relay R376 interrupts, at the contacts 372, the previously traced circuit for energizing in multiple the winding of the cutoff relay R470 and the upper winding of the answer relay R460, whereupon the cutofi relay R470 restores. Upon restoring, the cutofi relay R470 interrupts, at the contacts 472 and 473, the previously traced bridge connection, including the lower winding of the answer relay R460, between the line conductors of the trunk 4I5.

Finally the seizure relay R370 interrupts, at the contacts 373, the previously mentioned path for applying ground potential to the control conductor C4I4 of the trunk M I, thereby to mark the trunk 4H and consequently the repeater 4I0 as idle to the selectors having access thereto. Further, upon restoring, the cutoff relay R470 completes, at the contacts 4H and 474, obvious paths respectively including the contacts 452 and 454 and the windings 33l and 333 of the transformer 330 and the contacts 43I and 433 for applying battery and ground potentials by way of the upper and lower windings of the line relay R440 to the respective line conductors CH6 and C411 of the trunk 4l5 extending to the incoming selector 405; whereby the line relay included in the connector 401 is effectively shortcircuited in order to cause the connector 401 and consequently the incoming selector 405 to be released. At this time the trunk 406 extending to the connector 401 is marked as idle to the incoming selectors having access thereto and the subscriber line 40l extending to the called subscriber substation is marked as idle to the connectors having access thereto, assuming that the subscriber at the called subscriber substation Y has replaced the receiver of the telephone instrument thereat upon its associated switchhook at this time. On the other hand, in the event the subscriber at the called subscriber substation Y has not replaced the receiver of the telephone instrument thereat upon its associated switchhook at this time, the line switch 402 operates incident to the release of the connector 401 to lock the subscriber line 40! extending to the called subscriber substation Y out of service and to mark the subscriber line 40! as busy to the connectors having access thereto, all in accordance with conventional practice. At this time the repeater 4|0 is completely released and available for further use.

Of course it will be understood that the release of the repeater H and the release of the repeater 410 take effect simultaneously, whereby these two repeaters will become completely released and respectively marked as idle by way of the trunks HI and 4 respectively extending thereto substantially simultaneously. At this time ground potential in the repeater H0 is applied by way of the contacts I36 and the previously traced simplex connection to the line conductors CH and CIZ of the trunk in; and ground potential in the repeater 4| 0 is applied by way of the contacts 436 and the previously traced simplex connection to the line conductors CH and CIZ of the trunk I'D. Accordingly, at this time, the trunk Ill may be seized by a selector to extend a call over the trunk ID from exchange I00 to exchange 400; similarly, the trunk 4| I may be seized by a selector to extend a call over the trunk H] from exchange 400 to exchange I00.

In view of the foregoing explanation of the modes of operation of the repeater I In as a sending repeater and the repeater M0 as a receiving repeater, it will be understood that the repeater 4l0 is operative in a similar manner as the repeater I I0, when it is utilized as a sending repeater, and that the repeater H0 is operative in a similar manner as the repeater 4I0, when it is utilized as a receiving repeater.

While one embodiment of the invention has been disclosed it will be understood that various modifications may be made therein, which are within the true spirit and scope of the invention.

What is claimed is:

1. In a signaling system, a two-way translator comprising means for generating a variable first series of impulses, means for converting said variable first series of impulses into a directly proportional single impulse of a corresponding variable time duration, and means for reconverting a single impulse of variable time duration into a corresponding variable second series of impulses.

2. In a signaling system, a two way translator comprising means for generating a first series of impulses including a variable number of individual impulses, means for converting said first series of impulses into a single impulse of Variable time duration including a number of unit time intervals corresponding to the number of individual impulses in said first series, and means for reconverting a single impulse into a second series of impulses including a number of individual impulses corresponding to the number of unit time intervals of said single impulse.

3. In a signaling system, means for generating a first series of impulses including a variable number X of individual impulses, means for converting said first series of impulses into a single impulse of variable time duration including a corresponding variable number X of unit time intervals, and means for reconverting said single impulse into a second series of impulses including a corresponding number X of individual impulses.

4. In a signaling system, a pair of stations each having means for receiving a variable first se-' ries of impulses, means controlled by said receiving means for transmitting a single impulse of a corresponding variable time duration to the other station, and means at the other station controlled by said transmitting means for transmitting a corresponding variable second series of impulses.

5. In a signaling system, a plurality of stations interconnected by a trunk line and a simplex circuit, means at each station for registering a variable first series of impulses, means controlled by said registering means for transmitting over said simplex circuit a single impulse of a corresponding variable time duration, and means at the remote station controlled by said transmitting means for transmitting a corresponding variable second series of impulses.

6. In a signaling system including a first repeater, a second repeater, and a trunk interconnecting said repeaters; said first repeat-er including means for receiving a variable series of impulses; and means controlled by said receiving means for transmitting over said trunk for each said series of impulses a single impulse of a corresponding variable time duration; said second repeater including means for receiving over said trunk impulses of variable time duration, and means controlled by said receiving means for transmitting for each impulse received a corresponding variable series of impulses.

7. In a signaling system including a first repeater, a second repeater, and a trunk interconnecting said repeaters; said first repeater including means for receiving a variable series of impulses, and means controlled by said receivmg means for transmitting over said trunk a single impulse of a corresponding variable time duration; said second repeater including a generator operative to transmit a variable series of impulses during a directly proportional corresponding variable time interval, means for receiving over said trunk a single impulse of variable time duration, and means governed by said receiving means for selectively controlling the time interval of operation of said generator whereby said generator is controlled to trans m1t a variable series of impulses corresponding to the variable time duration of a single impulse received by said receiving means.

8. In a signaling system including a first repeater having a first line extending thereto, a second repeater having a second line extending therefrom, and a trunk interconnecting said repeaters; said first repeater including means for receiving over said first line a variable series of impulses, and means controlled by said receiving means for transmitting over said trunk a single impulse of a directly proportional corresponding variable time duration; said second repeater including means for receiving over said trunk a single impulse of variable time duration, and means controlled by said receiving means for transmitting over said second line a corresponding variable series of impulses.

9. In a signaling system including a pair of two-way repeaters, and an interconnecting trunk; each of said repeaters including first means for receiving a variable series of impulses, means controlled by said first receiving means for transmitting over said trunk a single impulse of a corresponding variable time duration, second means for receiving over said trunk a single impulse of variable time duration, and means controlled by said second receiving means for transmitting a corresponding variable series of impulses.

10. In a signaling system including a pair of two-way repeaters each having an incoming line extending thereto and an outgoing line extending therefrom, and an interconnecting trunk; each of said repeaters including first means for receiving over the associated incoming line a variable series of impulses, means controlled by said first receiving means for transmitting over said trunk a single impulse of a corresponding variable time duration, second means for receiving over said trunk a single impulse of variable time duration, and means controlled by said second receiving means for transmitting over the associated outgoing line a corresponding variable series of impulses.

11. In a telephone system including a calling station, a called station, a first repeater, a second repeater, a trunk interconnecting said repeaters, first switching apparatus associated with said calling station and having access to said first repeater, and second switching apparatus associated with said second repeater and having access to said called station; means controllable from said calling station for operating said first switching apparatus to seize said first repeater and for transmitting one or more digits to said first repeater, said first repeater including means for receiving a variable digit transmitted thereto and means controlled by said receiving means for transmitting over said trunk a single impulse of a directly proportional corresponding variable time duration, said second repeater including means for receiving over said trunk a single impulse of variable time duration and means controlled by said receiving means for transmitting to said second switching apparatus a corresponding variable digit, and means responsive to one or more digits transmitted to said second switching apparatus for operating said second switching apparatus to seize said called station.

12. In a telephone system including a calling station, a called station, a first repeater, a second repeater, a trunk interconnecting said repeaters, first switching apparatus associated with said calling station and having access to said first repeater, and second switching apparatus associated with said second repeater and having access to said called station; a calling device at said calling station operative to transmit one or more digits to said first switching apparatus in order to cause said first switching apparatus to seize said first repeater and then to trans t one or more digits to said first repeater, s id first repeater including means for receivin a variable digit transmitted thereto and means controlled by said receiving means for transmitting over said trunk a single impulse of a corresponding variable time duration, said second repeater including means for receiving over said trunk a single impulse of variable time duration and means controlled by said receiving means for transmitting to said second switching apparatus a corresponding variable digit, said second switching apparatus being responsive to one or more digits transmitted thereto in order to cause said second switching apparatus to seize said called station.

13. In a telephone system including a pair of two-way repeaters, a pair of switches normally respectively connected to said repeaters, and a trunk interconnecting said repeaters; means for seizing one of said repeaters and for transmitting a Variable digit thereto, and means responsive to the seizure of said one repeater for disconnecting the associated switch therefrom, said one repeater including means for receiving a variable digit transmitted thereto and means controlled by said receiving means for transmitting over said trunk a single impulse of a correspond ing variable time duration, the other of said repeaters including means for receiving over said trunk a single impulse of variable time duration and means controlled by said receiving means for transmitting to the associated switch a corresponding variable digit, thereby selectively to operate the said-mentioned switch.

14. In a telephone system, including a calling station, a called station, a pair of repeaters, a trunk extending between said repeaters and including two line conductors, and means for setting up a connection from said calling station by way of said repeaters and said trunk to said called station; said connection including a circuit extending from one terminal of a source of current supply in a first of said repeaters by way of the two line conductors of said trunk in parallel to the other terminal of the source of current supply in a second of said repeaters, and means responsive to a control operation performed at one of said stations for causing apparatus in said second repeater to disconnect one of the line conductors of said trunk from said other terminal of the source of current supply in said second repeater, thereby to transmit a supervisory control to said first repeater.

15. In a telephone system, including a calling station, a called station, a pair of repeaters, a trunk extending between said repeaters and including two line conductors, and means for setting up a connection from said calling station by way of said repeaters and said trunk to said called station; said connection including a circuit extending from one terminal of a source of current supply in a first of said repeaters by way of the two line conductors of said trunk in parallel to the other terminal of the source of current supply in a second of said repeaters, and means responsive to the performance of an answer operation at said called station for causing apparatus in said second repeater to disconect one of the line conductors of said trunk from said other terminal of the source of current supply in said second repeater, thereby to transmit an answer supervision to said first repeater.

16. In a telephone system, including a calling station, a called station, a pair of repeaters, a trunk extending between said repeaters and including two line conductors, and means for setting up a connection from said calling station by way of said repeaters and said trunk to said called station; said connection including a circuit extending from one terminal of a source of current supply in a first of said repeaters by Way of the two line conductors of said trunk in parallel to the other terminal of the source of current supply in a second of said repeaters, means responsive to the performance of an answer operation at said called station for causing apparatus in said second repeater to disconnect one of the line conductors of said trunk from said other terminal of the source of curent supply in said second repeater, thereby to transmitan answer supervision to said first repeater, and means responsive to the transmission of an answer supervision to said first repeater for effecting a reversal of the current supplied to said calling station.

17. In a signaling system, a translator comprising a register having a plurality of settings, means for receiving a variable series of impulses and for selectively operating said register to a corresponding one of its settings, a sender hav ing a plurality of settings, timing means controlled by the operation of said register to any one of its settings for operating said sender to a corresponding one of its settings, whereby said sender is operated a variable time interval to the different ones of its settings, and means for transmitting a single impulse during the time interval said sender is being operated to a corresponding one of its settings, whereby the single impulse transmitted by said, transmitting means is of variable time duration:

- WM. WALTER OWEN, Executor of the Estate of Bernard D. Willis, De-

ceased.

' CERTIFICATE OF CORRECTION.

Patent .No. 2,56og296; October 10, 19th.

BERNARD D, WILLIS, DECEASED,

BY WM. WALTER OWEN, EXECUTOR.

It is hereby certified that error appears in .the printed specification of the above numbered patent requiring correction as follows: Page 11, second column, line hO, claim 15, forteaid-meritioned switch" read --said last-mentioned switch"; and that the said Letters Patent should be read. with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of January, A. D. 1915.

. Leslie Frazer (Seal) Ach ng Commissioner of Patents.

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