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Publication numberUS1942404 A
Publication typeGrant
Publication dateJan 9, 1934
Filing dateJun 29, 1932
Priority dateJun 29, 1932
Publication numberUS 1942404 A, US 1942404A, US-A-1942404, US1942404 A, US1942404A
InventorsAshbrook Roy B, Burnett Alva M
Original AssigneeAssociated Electric Lab Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Telephone system
US 1942404 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

F2. B. ASHBROOK El' AL TELEPHONE SYSTEM Filed June 29. 1932 ITILIEHDFE HD5 B. R52-braak lua FI. 51m

will r l I I l Patented `an. 9, 1934 UNITED STATES PATENT oFFlcE nett, Alhambra, Calif.

Electric Laboratories, poration of Delaware assignors to Associated Inc., Chicago, Ill., a cor- Application June 29, 1932. seria1No.619,sso

'28 Claims.

Communication networks ownedby power ccmv panics are called upon to furnish a number of widely different services such asload dispatching; commercial department contacts between main offices and outlying districts; contacts between sub-omces and district oices, etc. Usually the telephone lines are terminated in a communication center wherein they are connected to one I or more dispatchers boards, to a wire-chiefs board, and to a telephone switchboard for making the connections to main oiiices and other lines. A large majority of these lines are of the party-line type, having a number of stations on the same line, over which the desired party is called by a code-ring consisting of a combination of long and short rings. l

Under the old method of operation, if a' magneto station desired to call another magneto station on the same line or any one of the several boards, the code ring was received on both the dispatchers board and the telephone switchboard, thus necessitating a constant vigil on the part of the operators in order that they might be able to determine when they were being called, which, from an operating standpoint, was very unsatisfactory. The present'invention has for its principal object the provision of a system in which this objection has been overcome practically from both an engineering and a commer- 40 cial standpoint.

The principal object of the invention is accomplished by providing equipment by means of which it is possible for a magneto station toselectively signal the board desired, by a' special code ring consisting of an initial long ring which will always be of greater duration than the ordinary long ring. By this arrangement, if a magneto station is calling another magneto station the selective signalling circuit, or ringing circuit, while successive short rings, succeeding the long ring, will select the boards as desired, lighting the line lamp on only the particular board desired. This selective signalling equipment will hereinafter be termed an alternating current selector, or, briefly, an A. C. selector, since it is actuated by the 162/3 cycle alternating current of the usual telephone magneto generator and since it is capable of selecting and extending connections to as many as twenty-five switchboards or toll lines. The result is, insofar as the dispatchers and operators are concerned, that the lines do not appear as party lines, their lamps lighting only when they are wanted and remaining lighted until answered.

VOne of the features of the present invention is that, with the A. C. selector disclosed herein, it'

not necessary to change or add any equipment on the magneto line since the A. C. selector will operate from the usualtype of telephone magneto or standard ringing machine.

Otherfeatures of the invention are embodied inthe various arrangements for notifying the Wire-chief vand dispatcher in case of trouble.

A complete understanding of the equipment and operation of the system and an appreciation of all of the features of the invention may be had from a study of the detailed description which follows, reference being had at the same time to the associated drawing, which, by means of the usual symbols diagrammatically depicts the system and apparatus of this invention.

In the drawing, there is shown one of a plurality of telephone lines, comprising conductors l and 2. This line has been shown as a party line having a plurality of stations A-A3, inclusive, connected thereto. The line 1 2 is multiply connected to the various boards, terminating in the jack J in the telephone switchboard, denoted in the drawing as operators position, in the jack J1 'in the wire-chiefs board, or position, and in the jack J2 in the dispatchers board, or position.

The station A consistsl of the usual ringer, transmitter, receiver, local battery, transformer, and hand generator, or magneto M, commonly used on lines of this character. Stations A1, A2, and A3 are similar to station A although they` have been represented by only the ringers.

The A. C. selector consists of a series of pendulum-type relays, slow-actingrelays 3-12, inclusive, and a rotary-line switch S, which is of the well-known type, the wipers of which move ina forward direction only. In the present system, there isone such A. C. selector for each party line 'indicate to theV wire-chief andthe dispatcher u, slow-to-.release relay 4- Y vafter an interval and, at its upper armature and which is to be provided with selective ringing service. Associated with each party line is a group of quick-acting relays 19-24, inclusive, arranged in pairs and allotted one pair to each position connected to the switch S. This relay group is considered as a part of the A., C. selector and the function of it is to control the lighting of the line lamp in the selected position andthe busy lamps in all positions when a call is answered.

The line relay 3 is an alternating current relay connected in series with a condenser in a bridge circuit across the line conductors l-Zandoperated by the alternating current generated by the magnetos such as M. f

Relays 5, 87 and 10 are relays of the pendulum type having weighted reed-like armature springs which vibrate between contacts for a considerable period of time upon the deenergization of the coil windings, finally coming to rest out ofengagement with both contacts. The desired dura'- tionof the vibratingperiodof relays ofthischaracter may be secured by regulating the position of weight on the vibrating member.

As astarting Vpoint of the detailed-description i ofthe operation of the system, it will be assumed that the party at station A desires to call another party on the line. The procedure in this case will be `the same as in any magneto telephone system, namely, the operation of the magneto M in accordance with the long and shortring code of the desired station.

The line relay 3 of the A. C. selector operates each time thefrnagnetoMV is operated and at its armature opens the normally closed circuit of Relay 4. deenergizes back contact, closes the circuit of vibrating relay 5 and in parallel therewith the circuit of the code lamps located at the wire-chiefs and dispatchers v positions and individual to the line shown. Relay 4, atits lower armature and make contact, opens the normally closed circuit of vibrating relay Sand, at the alternate contact of said lower armature, prepares a circuit for the motor magnetY 13 of the rotary switch S.

Relay 5 energizes, upon closure of its circuit by relay 4, and, at the make contact of its weighted armature, closes the obvious circuit of slowacting relay 6.

The codelamps at the two positions light-to that something is happening on the party line.

Opening of the circuit of relay 8 causes the deenergization of that relay, whereupon its armature commences to vibrate between the two contacts, thereby maintaining the circuit of slow-acting relay 7 closed suiciently long to maintain that relay energized.

Relay 6 operates when relay 5 closesV its circuit and, at its armature and make contact, completesV the circuit of the flash-over lamp at thedispatcli-k ersposition for a purpose-to be described subsequently.

Before proceeding further with theA description, 5.1. it will be explained thatrelays 8 and 10. are so adjusted that their contacts will vibrate for slight,- ly less than four seconds after the deenergization of the windings, while relay 5 is adjusted to vibrate its armature for twelve seconds upon.

deenergization of the winding.

" Upon` termination of the operationy of magneto M, relay 3 restores and re-establishes the circuit of relay 4, which, at its upper armature, opens the circuit of Vibrating relay 5 .and opens the circuit of the code lamps, and, at its. lower arma.-

ture, re-establishes the circuit of vibrating relay 8. Relay 5 thereupon deen-ergizes and the Weighted contact thereof commences to vibrate. As previously stated, this Vibration takes place for a period of twelve seconds, thereby maintaining relay 6 operated and, consequently, maintaining the flash-over lamp lighted for av period of twelve seconds after the restoration of relay 3.

Y Inasmuch as the long ring of the ringing code of any station on the line is shorter than four seconds duration,.the weighted reed of relay 8 will; not have ceased vibrating when the circuit of relay 8 is re-established following the restoration ofr'elay, and consequently relay 'l will not have been deenergized. As operation of the switclrS isisdependent upon the restoration of relay '7, as will be explained in detail a little later, no operators position will be selected and signalled when any operation of the magneto M for less than a four-second period takes place. Therefore, it is evident that any station on the party lineA cancall any other station thereon without causing any line lamp individual to this party line tovbe lighted at` any one of the operators boards. i.

Assuming, now, that station Av desires-a connection with the telephone switchboard-operators position, the'rnagneto M will'be operated for a period of at least foury seconds, this operation constituting the special initial long ring.

The operation of relays 4, 5,- 6, and 8, following the operation of relay 3, will'be thesame as described before. In this; case, however, relay 4 remains deenergized suiiiciently long to allow the armature of relay Sto come torest, whereuponv relay 7 restores. Upon restoring, relay 7, at-its lowerv armature, completes the-circuit of Vibrating relay, 10y from groundthrough resting contact andarmature of relay-4, and, at, its upperv` armature, opensthe` circuit of relay 10 and closesthe. circuit of the troublel lamp` aty the wire- Relay` 10 y operates when its circuit is completed and, at-the make contact of itsA weighted armature,Y completes the circuit of relayv 9, which thereupon operates. RelayY 9, at its upper arma-- ture, establishes a different circuit for the trouble lamp at thewire-chiefs board;r at its innerlower armature, opens, at that point, the circuit of relay. 8; and, at its lowermost armature' and,

make contact,I completes thecircuit of slow-tooperate relay 12 Land motor magnetlB. of switch S in paralleLirelay 4 still being deenergized. Motor magnet'13thereupon energizes preparatory to. advancing. the wipers 14 and/.15'out of their,

gizes relayj4, which thereupon attractsits arman-r tures. At:the, upper armature of relay. 4, the

code.` lamps are extinguishedand the'circuit'of relay' 5=is opened,whereu pon the weighted armature ofY relay 5 commences to operate to maintain the flash-over lamp lighted forv twelve 'seconds longer. At theflower armature of relay 4, theV ,circuits of- I relaysl0, andi` 12 are opened and the f'circuit fof-relay 8- prepared, this. circuit* being open at the inner-lower-armature of relay);

Relays y 12. restores. and.;.relayi'10;.deenergizes,. '1w-f whereupon the armature of relay 10 commences to vibrate. After a period of four seconds, the armature of relay 10 comes to rest and the circuit of relay 9 is opened, whereupon relay 9 releases, re-establishing the circuit of relay 8 and the original circuit of the trouble lamp.

Relays 8 and '7 operate in turn followingthe restoration of relay 9. Relay 7, at its lower armature, opens the circuit of relay 10 atthat point, and, at its upper armature, opens the circuit of the trouble lamp and re-establishes the circuit of slow-to-operate relay 11.

Before relay 11 attracts its armature, the following circuit is completed: ground, upper armature and make contact of relay '7, armature and resting contact of relayll, wiper 15 of switch S, rst position bank contact of wiper 15, conductor 16, normally closed contacts controlled by the lower armature of relay 19, and thence through the winding of relay 19 to grounded battery. Relay 19 operates in this circuit, at its upper armature, completing the circuit of the line lamp at the telephone switchboard, operators position, and, at its lower armature, completing the obvious holding circuit for itself.

When relay 11 operates after a short interval, it opens the circuitjust traced, and, at the make contact of lits armature, connects ground to all,

of the contacts of the bank of wiper 14 which are multiply connected. This ground is then extended by way of wiper 14 andinterrupting contacts of motor magnet 13 to the winding of the motor magnet, whereupon the motor magnet acts in a self-interrupting circuit to rotate the wipers 14 and 15 tothe sixth bank contacts of the respective wipers. It will be noted that the sixth, twelfth, eighteenth, and last contacts of the bank of wiper 14 are not connected with the other bank contacts. Therefore, when Wiper 14 reaches itsV sixth contact, no circuit will be completed for motor magnet 13 and, consequently, thewipers will come to rest. By this arrangement, a plurality of normal positions for the wipers is provided, thereby eliminating unnecessary rotation of the Wipers. v

The telephone operator, noticing the lighted condition of the line lampather position, an-

swers the call by inserting the answering -pluggf of her cord circuit into the jack J, whereupon the. jack contacts are closed to complete the obvious circuit of relay 20. Relay v20 thereupon operates, at its upper armature, extinguishing they line lamp at the called position; at its innerlower armature completing the obvious circuit of the busy lamp at the operators position; and,

' at its lower armature, opening the holding circuit of relay 19 and completing, by way of resting contacts and inner-lower armatures of relays 22 and 24, the circuits 'of the busy lamps at the wire-chiefs board and the dispatchers board, respectively.

Thus, it will be seen, one prolonged operation, of at least four seconds, of the hand generator results in the ringing, or signalling, of the teleseconds has lapsed between the initiallong ring and the short ring, the armature of relay 10 is still vibrating when relay 4 restores, and, consequently, relay 9 is still operated. Therefore,

restoration of relay 4 this time completes, -at its onds afterthe termination of the long ring, relay.

8 is not reoperated until a period of at least four seconds between rings occurs. Therefore, no circuit for one of the line lamp relays 19, 21, and 23 is completed until at least four seconds after the last ring have lapsed. Consequently, since the short ring occurred within about one second after the long ring, relay 7 was deenergized and no circuit was completed for relay 19 while wiper 15 was standing on its rst bank contact.

Four seconds after the reoperation of relay4 upon the termination of the short ring, the armature of relay 10 cornes to rest and relay 9 restores, whereupon relay 8 operates and operates relay 7. Relay 7, upon operating, connects ground to the winding of sloW-to-operate relay 11, and through the armature and resting contact of that relay to wiper 15. Since, at this time, wiper 15 is standing on its second bank contact, the ground is extended over conductor 1'7 to relay 21, which relay then operates, at its upper armature lighting the line Vlamp at the wirechiefs position and, at its lower armature, completing the holding circuit for itself.

Relayl 11, upon operating, at its armature and make contact, completes the previously-traced circuit through wiper `14 for motor magnet 13, whereupon the wipers 14 and 15 are advanced to the next normal position.

AThe dispatchers board can be signalled by following the initial long ring by three short rings second intervals between rings. This results in the placing of wiper l15 on the fourth contact. from the normal position. in this position and four seconds after the last ring, the circuit of rey to the normal position as explained.

Answering of calls by the wire chief and dispatcher result in the operation of relays 22 and 24, respectively, as'is evident, whereupon the busy lamps at all positions are lighted'.

Thefcapacity of switch S when wired as shown is five positions. nections of the positions to the bank contacts, the

capacity of the switch can be increased to twentyve positions. As an alternative, a rotary line- 4 of about one second each without about onel However, by changing the conswitch of any capacity desired can be substituted for the switch shown.

Attention is especially directed to the impulsecorrecting and repeating arrangement whereby motor magnet 13 receives impulses of uniform length whenever the operators code, wire-chiefs code, or dispatchers code is received by the A. C.

alternating current impulses of varying duration received by relay 3 are repeated to motor magnet 13 by relays 4 and 12 as direct-current impulses of uniform lengthV since" the time" reduiied wfoi slovieto-operate relay' 12t`o` attract its? armature is constant for all practical purposes;

The purpose of the' code lamps istogive'tli Wir' Chief andV dispatcher VisualL indications; (Sik the codes' impressed up'onthe A. Ci selector so that' they can supervise all calls as desiredfregardlessoi" Whether'or not their dvi/'n' codes are being impressed upo'n theselect'oi". Y

The purpose of' the trublelampat: th'eviirechiefs position istofgive' a` vi ual' indication o'ff any trouble occurring initheA.' C: selector. If any/of therelays43-7, 8j 9j or lll'riilain-inapwiitin other tha-'ri shovv'nv in the dravv'inrg]-p'errnl` nently, the trouble lamp"'isbrouglit iii-l and{inanitained until the trouble has been remedied; '.'El'el trouble'lamp alone is'li'ghted'whenfany of' relays '7, 8; 9, o'r` 10 arey at fault.

' tion is for the purpose offiiifr'ning'thedispateher of the approximatelocation of an abnormalcoil ditioiionthe power transrnission syste'riii' In privately oWnedtelep-iio'ne systems thefterfdescrib'ed herein, it scornriorif practice to'A hunde teiep'noneunjointly warf-a gardenia? transmission line; Therefore, whenll anabr'i mal condition exists on a transit'iivssionj` linegf thev induced voltage on" the' joint telephone line is usually sufficient2 to :nonientarily'0" 1d`e'rateasensitive'line relay such as' relay`3f Suchanop r4 ation of relay'B results in a-mo'frnentary deeifiergf-` zation of relay 4 and' a' conseciient;I rionentary energization'of relay 5L Relay tlereuponfop? eratesrelay 6, which brings inthe flash-lover` in# `idication to the dispatcher. The vib'atingarrnai ture of relayl 5 maintains relay 6 operated*forr twelve' seconds after the 4rnornentary e'nergization of" relay 5. This maintains the asliover lamp Y lighted for tvvelve' secondsV aftern thesurge in tlie V.telephone line. The dispatc'he1 getsan indication of the trouble from his instruments-'and ari indication of the approximate location ofthe trouble from thel flash-over larnp.- V

The invention having' been thus described, anni I isf'considered new and is desired to' have p'rfte'ted byLetters Patent is described in the claims which' follow.

What is claimed is: 1l In a telephone system, an operatorsfpo's'tion, a party line terminating in said position, a magi neto for each subscriber on said partylin'e-j,meansy responsive only to the operation ofone ofs'a'id Inagnetos in aecordancel with :one 'particni'arfcode for signalling' the operator, and means respon'-v` -fsive to the operation of one of said'magnetosin accordance with the code assignedto 'a'sub'scrib'r on said line for'preventing the operatorfrorrrbe'A ing'wsign'alled.

magnetos in accordance with 'one particular:code` comprising a ring of predetermined duration vf' loWed by another ring for operating 'said linefsig nal, and means for preventing the operation( of' w x case of troublewfor lightingthetrouble lamp said line ysignal responsive tothe operation of 'one ofsaidjmagnetos in accordance Withy subscriber co'de rings when a subscriber calls another subA scriberon his own line. n U Y i 3; In Va telephone system",` an operators posii linesgn'ali forsai'd line at said position, means `r meenden@ witii'fdiff rentindfef selecting-anar operating differentv ones of t said lin signals.y

erat'ois pfdsitio'nsflaV party line' terminating'` in subscriber on saidy ifigffo'r the operation of any1 nals,- andvi means responsive accordance' with a prlongd" ring for preparing lfr" the operationr of any'on yof said ne 5 signals; lrnea'nsfrespo'nsiveI tions'- o f saic'ilniagfnetoin'r`r accordance Awithl 'different cordes'iforf selecting 7 andoperating! diiie're'nt one's'fof said line signalsj'and In'eansrespnsive t'oia': calliri'gsubscr'iber operating his rfagiieto 'n'ac'cordance v iritli a subscriberscdeffo'r rendering said preparingme'ans inoperative;u A

6. In av telephonen system, an: o'lterat'ors posi-PI tionja` calling line 'terminating in said position,

aline'fsigrial for said line fatsaid' position, afco'rn binedtiming'- andselectinvg device, a hand genera-Y to'r `on s'aid line, and vmeans responsive to the operationofS said' g'ener'atr' in accordance Ywith 7. In a telephone system, a plurality"o`f'op'era-r tors` positions;v ar party 'line' terminating l i fsaid statio'n :on said `-linef"for"signalling isubscribers jon' responsivef toi the Y'op'ervition of ing? sa'id devic'eift select' operate "only one of said line signals; i theI 'operated signal corresp'onfding''to /the operated fcodev.'

S'I'In a tlephone'system', vva Wirel chiefs posi;v

tion', a S partylineterriiinating in saidfpositionv a) tfslblel'aljd @de lamp @1553101111116 ,at Said posi-l. tion; a'selecting device associated'with said-line,

hand generators on said line forfsig'nalling by:

codefsubscibrs :oni said line and'jfbr operating said device, means responsive'xto' certain codes forv operating'lsad viev-ice to' operatpothsaid lamps, a busy lamp for said line -at said position',- means for operatingsaid'E busy lamp When',` aca-llfdis answeredlf-'andvv rneansy operative responsive to a' 9L In'V a"te1ephonef av lripara-i torsj positiem ajsubscribers line; terrninatin'g at trouble on power transmission lines for operating said signal whereby the dispatcher is informed by the combined operation of the trouble indicators for the transmission lines and the flashover signal the approximate location of the trouble.

10. In a telephone system, a dispatching operators position, a subscribers line terminating at said position, a flash-over signal for said line at said position, and means for operating said signal responsive to currents being induced in said line from an adjacent power line.

11. In a telephone system, a dispatching operators position, a subscribers line terminating at said position, a flash-over signal for said line at said position, and means for operating said signal responsive to a subscribers call and responsive to currents being induced in said line from an adjacent power line in case of trouble.

12. In a telephone system, a line terminating in a plurality of operators positions, a signal for said line at each position, a hand generator associated with said line, and means responsive y to the operation of said generator in accordance -with a particular code for operating only the signal at a particular one of said positions.

13. In a telephone system, a line terminating in a plurality of operators positions, a signal for said line at each position, a plurality of subscribers stations on said line, a hand generator for each station, and means including the generator at a calling station for selectively operating the signals at said positions.

14. In a telephone system, a line terminating Ain a plurality of operators positions, a signal for lof said positions, a combined timing and selecting device, a hand generator on said line for operating said device, and means responsive to the operation of said generator in accordance with a particular one of said different codes for operating said device to select and operate only the line signal at a particular one of said positions.

16. In a telephone system, an operators position, a combined timing and selecting device terminating a branch of said line, a line signal for said line at said position, hand generators associated with each substation on said line for signalling the subscribers on the line and for operating said device, and means responsive to the yoperation of one of said generators in accordance with a predetermined code for operating said device to select and operate said line signal. v

17. In a telephone system, a line extending from a subscribers station to a plurality of operators positions, a current generating device associated with the line at the station, a signal for the line at each position, and a switch controlled by said device for selectively operating said signals. i 18. In a selecting device adapted to receive series of impulses varying in numbers of impulses and durations of impulses, the combination of means for directively operating said device in accordance with the number of impulses in a series, and timing means for rendering said first means effective only when the iirst impulse of theseries is of a particular minimum duration.

19. In a selecting device adapted to receive series of impulses varying in numbers' of impulses and durations of impulses, the combination' of meansy for receiving said impulses and repeating them as impulses of uniform'duration, a multiposition device operated by the uniform impulses to a position corresponding to the number of impulses'of the received series, and timing means for rendering said rst means elective to repeat impulses only when the first impulse of the received series is of a particular minimum duration.

2G. In a selectingdevice adapted to receive series of alternating-current impulses varying in numbers or impulses and durations of impulses,v

the combination of means for receiving a series of alternating current impulses and repeating V them as direct-current impulses of uniform du'- ration, a multi-position device operated by the direct-current impulses to a position corresponding to the number of impulses comprising the received series, and timing means for rendering said iirst means effective to repeat impulses only when the iirst impulse of the alternating-current series is of a particular minimum duration.

21. In a selective signalling system, a multiposition switch, a diierent signal operable in each position of said switch, means responsive to successive impulses for progressively operating said switch to its diierent positions, and timing means for automatically operating the signal of the position in which said switch is standing whenever a definite interval of time lapses between two successive impulses.

22. In a selective signalling system, a multiposition switch having a normal position, a diiierent signal operable in each position of said switch except the normal position, means responsive to successive impulses for progressively operating said switch from its normal position to its different positions, and timing means for automatically operating the signal of the position in which said switch is standing whenever a denite interval of time lapses between two successive impulses and for thereafter returning said switch to its normal position.

23. In a selective signalling system, a multiposition switch having a normal position, a different signal operable in each position of said switch except the normal position, means responsive to series of impulses of varying durations for progressively operating said switch from its normal position to its other positions, timing means for rendering said iirst means effective to operate said switch only whenever the rst impulse of a series is of a particular duration, and other timing means for operating the signal of the position in which said switch is standing whenever a ltime interval of definite duration lapses between successive impulses and for restoring said switch to its normal position.

24. In a telephone system, a telephone line having means associated therewith for transmitting series of impulses varying in numbers of impulses and durations of impulses, a plurality of operators positions multiply connected to said line, means controlled by a series of impulses transmitted over the line for signalling the operators position corresponding to the number of impulses comprising the series, and timing means for rendering said signalling means effective to signal an operators position only when the first impulse of the series is of a particular minimum duration.

In a telephone System a ,lino @plurality of stations conneoted. to said line, a signal vfor sail 1in@ .at .eah station, a ,hand generator associated With Safd lille and means ISSHQBSV? tf? $119,093@- riQrr `or .Said vgenerator .irl rfsr'erdarroe with a par: tisular 00de for operating Vthe Signal at a particular yone of said stations only.

2 6. In va telephone system, a line, two groups of stations on said line, a signal'for s ail line at Q SfQUSaOn 0f ear-C11 grOU-.P @hand gnfalor $155.9.' @rated with Said line, ,the Signals Qf erre group 0f stations operating responsive to the operation of Said `g.l??31"?15101 in @CQC-lance ,With any 00de and me'ms 179.5901351@ t0 the Qiefaton .0f 3 p?.ft..Cu1.?1` c ole for operating'tlie signal of a `particular statQn 9.1115 .0f the Sep/.9nd grQU-p- 277. In an impulse orreoting and repeating dev ioe, an alternating current relay adapted to receive a series of alternating current impulses Varyirre rrr duration and adapted 't0 respond t@ `earl; impulse '0f .the series, means for .transmitting direct-Curr@ impulser .Qf .uniforrrrqrrrrrrirr rrd timing means f.-01`.D,1?C,.1.g .Sad m9111513 l'flfnmii? mig mallsllnl BQQQIIIO Said afufnllg.' ourrent relay only when the first alter'I'iELtirIg current impulse of the seriesis 1of a particular

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2549688 *Oct 18, 1947Apr 17, 1951Automatic Elect LabMagneto party-line adapter
US2753403 *Nov 30, 1954Jul 3, 1956Caracciolo Joseph PSelective signal system
US4293737 *Dec 6, 1979Oct 6, 1981Mitel CorporationRinging decoder circuit
Classifications
U.S. Classification379/187, 379/371
International ClassificationH04Q5/00, H04Q5/20
Cooperative ClassificationH04Q5/20
European ClassificationH04Q5/20