US1600358A - Remote-control system - Google Patents

Remote-control system Download PDF

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US1600358A
US1600358A US700953A US70095324A US1600358A US 1600358 A US1600358 A US 1600358A US 700953 A US700953 A US 700953A US 70095324 A US70095324 A US 70095324A US 1600358 A US1600358 A US 1600358A
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relay
switch
circuit
contacts
wiper
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US700953A
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Puckette Charles Clarke
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COVENTRY AUTOM TELEPHONES Ltd
COVENTRY AUTOMATIC TELEPHONES Ltd
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COVENTRY AUTOM TELEPHONES Ltd
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Selective Calling Equipment (AREA)

Description

Sept. Z1 1926. 1,600,358
c. C. PUCKETTE REMOTE CONTROL SYSTEM Filed March 21; 1924 `2 sheets-sheet 1 Sept. 21 1926.
C. C. PUCKETTE REMOTE CONTROL SYSTEM Filed Mrch 21. 1924 2 Sheets-Sheet 2 fai/97 Patented Sept.l 21, 1926.A
f telef-sse UNITED STATES arent oeillet.
CHARLES CLARKE PUCKETTE, OF STOKE, ENGLAND, ASSIGNR T CVENTRY AUT- MATIC TELEPHONES LIMITED, 0F
Retroen-oemneL erstma.
STQBLK CVENTRY, ENGLND.
Application lcd March .921 1924, Serial No. 700,953, and in. Great Britain eccmlier 27, 1923.
This inventionrelates to systems for con-- trolling and supervising the operation .ofi electrical. machinery from a remote point over line wires. i
The object of the present inventionis to provide a remote control Asystem wher(I the sclexting devices coneist of electro-magnetic Step-by-step two co-ordinate switches.
.which used in conjunction with a limited number of rotary switches and relays con tains several novel operating and control features.
The system will be described in connecwith a power distributing arrangement in which a power substation is controlled from a main power station over wiresl between the main and the substation, the despatchcr being situated at the main stru tion. A pair bf telephone wires are connected between the main station and the substation, and a telephone .fitted with an impulse transmitter is located at tile main power station over which the despatcher performs and supervises power control operations at the substation. The impulse transmitter' may be similar to that described in the specification of United States patent specification No. 1,324,356, so an ranged that the line loop is broken a .nun'iber of times according to the digit pulled or dialled. At the substation asimilar telephone set is installed, to enable tbe whole of the automatic remote control equipment to' be operated either from the main power station or the-substation; also to enable telephonie communication to' be established between the two points. At each substation is installed a one' hundred point. two co-ordinate selecting switch which may be similar to lthat shown in Unitedy States patent specification No. 1,076,020. This switch is adaptedfto make a selection (out of one hundred) by movements in two planes. It first makes a number of rotary steps according to the tirst train of impulses (tens) to select a particular row :mzl then make a number of vertical steps accordiingr to the second train of impulses (units) to select a particular set of termin nuls in that row. The substation equipment also includes several rotary step.b}:- step swith`es and a/ quantity of relays.
By the niuuipulution of his impulse transmitter the despatcher directs the selecting switch at a substation so that the wipers engage e particular set of terminale. 'Thus if the despatcher dials 2 and tben on the impulse transmitter, the selectingr switch makes two rotary steps followed by seven vertical steps so that the wipers engage the set, of terminals twenty seven. This mabbe a position correspon(linel to a certain condition of supervision and control us will bc afterwards explained.
A feature of rangements in 'which the despatcher after setting the two coordinate switch by two trains et' impulses (tens and units) receives signals corresl'iomling to the distinctive setting of the switch, thus verifying that it has been correctly positionedI before the control operation is performed. patcher may or may not proceed with the operation after receiving the signals.
.ft further feature yrelates to the method of signalling. The tens and units signals must be easily distinguisl'iable from eacl'i other and, 'for example, a' bell may be erni'iloyed for the tens signals and a buzzer for the units signals. Suppose that the des patcher wishes to perform :i control operation coireeponeliupY to a settingr'of thirty# live on the two (fo-ordinate switch. He would manipulate his impulse transmitter to send out first a train of three impulses followed by a train of live impulses. lle would then verify the selection by placing.; the telephone receiver to his ear. lf the switch is correctly positioned lie'will hear three rings from tbe bell followed by live impulses from the. buzzer. This will be repeated continuously .until ythe despatolier performs a further operation by which he proceeds or discontinues with the control.
Reference should noiv be made to the accompanyiner drawings in which at the main Station A Fig'. l is shown the telephoneI with impulse sender, the remainder of Fig. 1 and the whole of Fig. 2 being at one of the substations ll. rThe vtelephone circuit is not shown in detail as this is unnecessary and furthermore. is not confined to any particular arrangement. lt is understood, however, that by the manipulation of the impulse transmitter l the line circuit is broken a number of times in accordance with the digit dialled. Telephone B .is situated' at the substation and is provided to permit the operation and control of the equipment in the same way as with teletlie invention relates to ar-l The desapgiaratfus located i Gil phone A. Furthermore, telephone. conversation can be carried on between the two telephones. The two co-ordinate switch C at the substation, which may be of the type already referred to, is shown by its terminal banks 51 and 52, wipers 5B, 54, 55; and 50, rotary stepping magnet 57, vertical stepping magnet 58, release magnet 59, oilnormal springs 60. which operate when the switch makes its first rotary step, and oil normal sprinfs 61 which operate when the switch makes its first vertical step.
rotary step-by-step switch is indicated at D, Fig; Q, by its magnet 101 and singleended wipers arranged as shown at 102, 103, 104 and 105 and cooperating terminal banks. A second similar switch is indicated at E by magnet 106 and double-ended wipers 107 and 108'and co-operating terminal banks. The Wipers 109 and 110 are attachments of measuring instruments and will be referred to later. At 62, Fig. 1, is shown themagnet of a single motion rotary step-by-stepswitch F, wipers of which are indicated at 63 and bank terminals at 6a. This switch is of the kind commonly used in automatic telephony and is arranged. to supply alternating current for ringing pun poses in the 'following manner. The wipers 63 of this switch are connected to the incoming controlling Wires, and the corres ending rows of bank terminals 64 are a ternately multiplied to the two leads extending to the line relay 65. In this manner when the switch l?A is stepped, the current from the battery connected to the windings of the line relay is converted into alternating current which rings the bell at the main station. At 111 is shown a signalling set consisting of a microphone 112 placed in a closed box in close prox` imity to a buzzer 113 and a trembler bell 114. A second signalling set is shown at 115, and consists of a trembler bell placed vin a closed box in close proximity to a microphone 117. The section lining on certain relays indicates that they are provided w'ith copper slugs onsleeves to render them slow releasing. V
Returning to the two (Jo-ordinate switch, it should be noted that the banks 51 and 52 are for the purpose of simplification in the drawing shown so that selection is made in the following manner.
The firstl selection (tens) moves the wipers Ivertically in the drawing and the second selection (units) moves the Wipers horizontally to engage terminals in the row. Switch C, of course, may be of tbe-wellknown Strowger type 'used in automatic telephone systems.
Suppose now that the despateher wishes to start upv a machine at the substation the selection o.; whichcontrol is* by number Vseventy two. master control relay shown vmores the receiver from telephone .fa
ing upon terminri .s
in the drawing at l0 is connected to the bank terminals of the two coordinate switch so that it can be operated when naar ber 752 is transmitted.
The master control relay upon operation complace the. circuit ci the machine in any Well lnown manner. Similar relays will be associated with othe benl: terminals.
The complete oper. i is 1 losing the line loop. 4l-lfiper 53 will ofbzmlri' loop closure a. circuit i y G5. Relay operat t at conta-c completes the circuit l'or relay via normal contacts of key 0S? and release .o'xagnet springs Relay (57 nieuwe taets 70 completes the from earth at oli-norm ing relay 71 to opty i dials the digit 7 on n impulse transmitter causing the line loop to be broken seven times in rapid succession. l'elay 05 responde to the impulses falling away each break and completing a circui steppingniagnet 57 as folle earth at back contacts 66, operated co1` `ts 72, baci; contacts, bottom springs acti, magnet 57 to earthed battery. The switch makes seven rotary steps and on the first step springs 60 operate to open the original ens L s v or ro-.ary
ergizing circuit of relay 71 whss'n relay is now held from earth at springs 74, these springs being closed-by the armature of magnet 57 when in its attracted position. During impulsing both relays t5? and 71 receive current intermittently, but being slow releasing do not tall away. lWhen the impulses cease relay 71 releases and completes the i l lowing circuit: earth at operated springs 60, back contacts 7 5, normal springs 1'31, relay 76 to earthed battery. and prepares the circuit for the vertical stepping magnet 58. 'he despatcher dials the second digit. 2 and relay 65 again responds to the impulses completing a circuit 'for magnet 58 each time the relay releases -as follows: earth at baclr contacts 66,
operated contacts 72 and T3, magnet 5S to i earthed battery. The switch maires two vertical steps and upon the tirst operation of the armature ot magnetsprings 77 Relay 70 operates again complete a circuit for relay 71 over.,
cuit for `magnet 101.
.operation breaks the Circuit. of relay 1.10
owing to the relai; 1..1
Lemme Relay 76 falls away end e?" s tire cuit of relay '2'8 as follows: e ed spririgs 60, operated con@ contacts 80, 81 and 82, reley battery. l
Relay 78. upon operation et contacts 83 end Se places earth on wipers sind 56 and,
'as the terminals or" the @zo-operating barril:
52 are cennecterl in Suche nmiiiier :is te indicate by 'their multiple connection the position er' Wipers 55 and 56 (entitiereere 53 and :511) by earthing numerically corresponding; terminals on the benk associated with wipers 102 and 103 ofthe retaryswitcli, Fig. El, the dialled number is repeated rurali bly te the despatclier in the follewirig .man ner.
Since ffzeventytwo has been iliellerl by the despzitelier Wiper 5 5 wil be resting on terminal 86 and Wiper 50 en terri'iiriz-il. 87 of bank 52. a circuit for Slew-release relay 11.9 is follows: earth contacts 811, benl: .120 ot Switch D, interrupter spring 118, relay 119v to em'tlied battery. rt contacts 123 relai7 119 completes a circuit for relay which operates and at contacts 125i completes fr eirlilafrriet 101 upon which releases slowly and opens the eirjuitl of relay 124 which also releases slowly mil opens the circuit of magnet 101. Muguet 101 releases, again completing' the circuit oi relay 119 and the cycle of operations is re peetefl. Thus switch E steps at u slow rare (say about. live steps per Second) by relay interruption between magnet 101 fmfl relays 119 anti 121 und when wiper 102 reaches terminal 126 the following circuitis-completed earth at operated contacts: 88, teririinaly 80, wire terminal 1526, wiper 102, relziy 1:37 to eartlietl battery. Relay operates :mtl at' f'ontnets 128 loelr; up to resistance earth 129 :md grounds wiper 102. towiteli D con? tinues to step and When on the next termimi 130 relay 131 is operated over arm 102. armature 121% and reeistnnce earth 1291 It vwill lie seeirupon examination 'of the twink connections of switch D that relay 131 is, operated for the first time when Wiper 102 rests on terminal 1530, Sine@ previene en# gagements of tlie Wiper 102 i'ierreetire i n ingr inert and the circuit of relay 131 Open at armature 1li. It is again operated when wiper 102 reerliee every alternate terminal that in ffoziipleting the half circle relay 131 is operated for seven short periods. At ezieli operation ef relav 131 the following circuit is Completed: eartlied battery, bell 114,' operated "ontzicts 1321 operated contacts 84 to earth. 'Bell 114 will tirer-etere give seven eliort rings. At contat-ts the circuit of niicrophonel is completed through te hack contacts 89 and ,so that the despatelier lietemiixgA en the At Contacts 81 relay TF5 eorrmletesv line will hear tire geren riigs. illien Wiper 102 reaches; terminellfll better-V 131 will oppor-:e the battery connected to the winding of relay 127' which releases, opening contarts: 128. The wipers 102, 103, are a ranged 180o spart so that when the Wiper 102r leeres lits bank, the wiper 108 en- ;rzigves the .tiret Contact .in its benk. Switch D continues to step nml when Wiper 103 reaches terminal 13:3' the tollewiug circuit is completed: earth et ope attesi contacts 823, wiper 30, terminal tl?, wir' {lL-terminal wiper 103, reley 12"( to eartlietl battery. lelziy 12? again operates amil contacts- 128 locks up to resieence earth 129 and grounds Wiper 103, "when wiper 103 is steppefi on to the next terminal130,relay 137 operates to resietruice earth 129, and it will lge again operated on the next terminal but one. ll-''lieri 'Wiper 103 reeeiies terminal 138 battery 131 airain @preses the battery conv- :reeerl to winding or reley 12? "which releafres. ..lay 155? is thus operetetl 'for two f-:liort periode :mil at ezieli operation the following ,-irisit is completed: earth et contarte '811, operated contacts 139, lnizzer 1125 to ezrrtliefl, l'mtterjy. Emmer 113 'will therefore ,frire two Short lmzze' which will be heard by the despetclier. Switch D conf standing with its Wipers on {lizillinja fiirtlxer digit Suelras one. TWO
mi'lilwfl restoring wipers 104. 105, are provided. arranged apart. 1When the Cles prt lier hangs; up, i cireriit over the interruptor contracts 118 continues to be completefl for tlie relay 119 Aover one, or in SueT Ul Camion. liotli. of the Wipers 1011, 105, and their lwnifs 120, 121, until the wiper 104 lezu'ee ite lust Contact and. tlie wiper 105 en- ;I'ngef; a merid Qontfre '.llie relays 119, 124,
thereby interact with 'the etejmino' i'naiiet 115 101 previously (les ii'il.seil,u1it.il the switch refs real to norinal.
me that Vtrie flespatelier proceeds wtn the operation, Wliei'i rela7 65 releases 'lor the break of the loop it Completes,` the 120 ellowiiiq circuit: earth at. baek contacts 66, rmemtefl contacts '72., beek contacts 72, operatecl springs (il. relaiY 92 to eartletl battery.l Relay 92 operates; :and Wl'ien relay 65 again n* energizes `mi 'che following remake ot the 1' loon a'eireuit is Coirmleterl for relax' 03 as follows: earth :it operated springs 00, oper- :ftecl contente 79 emi. 94. relay 93 to esrrtlied battery. Relay 93 operates, locks up over contacts 215, 79,160, and :it eontacts S0 breaks the circuit of relay 78 and completes an energizinihY circuit for relay 50. operates and-at contacts 80 and 00 disconnects the microphone signalling circuit and switches through battery and earth from retardation coil 49 to wipers 54 and 53 respectively.
The number seventy-two having been dialled wiper 53 will be resting'on terminal 48 and wiper 54 on terminal 47 of bank 51 so that an operating circuit is completed for relay 46 extending over the windings of coil 49, contacts 89. 90, Wipers 54, 53 and contacts 47, 48. Such a. relay as 46 would be used as a master relay controlling heavier circuit and power controlling switch gear of any known kind to start the machine. Another relay 46 similar to relay 46 is provided and energized' by dialling the number 74, to initiate the stopping of the machine. A telephone transniitter such as may be located in close proximity to the machine (generator, motor or the like) in the circuit of relay 46 sothat the sound of the machine in starting could be audibly transmitted to the despatcher. Condenser 44 is connected to improve this transmission.
Should. tli'e despatcher, after dialling a number, decide not to go through with the operation corresponding to that number, the whole ot the equipment can be restored to normal by simply replacing the telephone receiver. This results in the deenergization ot relays 05 and 07. Relay 0T at contacts 96 completes the circuit for the. release mavnet 59 as follows: earth at operated springs 00, back contacts 96. magnet 59 to earthed battery. Release magnet 59 operates, releases switch C and opens contacts 69 to revent the energization of relay 67 until tie switch reaches normal. This'en sures that the switch 'will be fully restored.
Condensers and non-inductive resistances shown across the magnets are provided to minimize sparking at contacts.
The main despatcher may wish to read power indicatingr meters at the substation, such as voltmeters, am meters, or other meas` uring instruments of a like nature. and, by
. way o illustration a meter readingir circuit has -been added to the drawing. The circuit shows the rotary switch E employed in a manner somewhat similar to switch l) to indicate the positions of a voltmeter or ammeter by anumber ot signals transmitted to the d espatcher.
l himself that the two co-ordinate switch is standing4 upon the proper terminals, he
l'sends the operation impulse. ,Wiper 53 will ne resting on terminal 40 and wiper `54 on Relay terminal 41 that a circuit is completed for relay -143 over the windings of coil 49, contacts 89, 90, wipers 54, 53, contacts41, 40 throughmicrophone 117. At 110 is shown a rotatable arm capable of engaging:- a number of Contact. studs. This arm 110 may be part of or attached to an ammeterpointer so that, the stud upon which it is resting is indicative of the ammeter deflection./ This arm 110 is shown resting on stud 144, thus corresponding to a certain ammeter reading. Arm 109 and cooperating studs may befor Voltage reading. Relay 143 upon operation 'atcontacts 145 conn pletes a circuit for slow-release relay 146 via interrupter springs 147, which relay operN ates and at contacts 148 completes a circuit for relay 149. Relay 149 operates and at contacts 150 completes a circuit for mae"-` net 106. 'Magnet 10Gv upon operation breaks the circuit of relay 146, which releases. Relay 146 opens the circuit of relay 149, which releases and opens the circuit of magnet 106. Magnet 106 releases, again closes the circuit of relay 146 at springs 147,- switch E maires a step, and the whole cycle ot' operations is repeated. The control and signaling circuit are similar to those described in connection with switch D and associated relays so that only brief description will be necessary. When Wiper 107 reaches terminal 151 the following circuit is completed: earth at operated contacts 145, arm 110, contact stud 144, terminal 151, wiper 107, relay 152 to earthed battery. Relay 152 operates and loclrs up at contacts 153 to earthed resistance 154. On the nextstep of switch E the resistance earth is ex tended to relay 155, which operates, and at contacts 156 closes the circuit of bell 116.
The bell is rung at eaclralternate step and when wiper 10.7 reaches. terminal '157 bat` tery is connected to the wiper to oppose the battery connected to the winding relay 152 and cause its release. It will be seenthat fire rings are given by bell 116 Ywhich will lic heard by the despatcher over the line i'roin microphone 117 and will indicate to him the approximate readingof the ammcter. The ve rings. will be repeated at intervals due to the continuous stepping of of switch E until the despatcher releases.
llE the despateher dials nine-eight, Wipers 53 and 54 will be stepped on to terminals 3S and 39 respectively, causingr the operation tion upon release, the relay 146 being eaer`- mousse l n 5 gifted over the wiper 108 until the wiper engages n lead contactin the normal position of the switch. y. A
Such a .method'ot' determining quantities I can be employed in many ways, such the testing. of the height or" the level of Water in u tank or other receptacle; also the reading ol tcn'iperutures over a 'fairly rough 'soule can be performed by methods similar 19 fto this.
20 exceptifor the time they are actually placed in operation by the wipers ot .the operating bank, are totally dood or inert, By' this arrangement I obviate the possibilityK of an accidental operation which l`would be productiye fof serions ond expensive breakdowns in a substation. This is a feature ot considerable importance and obviously not liniited to a system employing two coordinate switches, but is equally applicable to .relay 3 and other switching systems.
Suppose fthatthe dispatcher at the main power station desires to ring up the substation to ascertain it there is anyone there, say, for example, an inspector. He dials a nunc her set aside for this purpose, whiclu in the drnwin is shown as 00. When the dcs- E? patcher has dialled O Wiper on will be sresting on terminal 4&2 and Wiper Fri on ter minalS. The crcuitof relay lfif will be completed, the relay operating und closing at contacts 14() the circuit -tor bell Mil. it someone is in attendance, he answers by removingr the receiver troni lthe substation tele* phone B. This breaks the bell circuit at contactslll. which are contacts of the switch hook of telephone B but for simplification in the drawinj are not shown associated therewith. A rey can be used instead of,
switch contacts 142.
Should en inspector visit the substation for inspecti n purposes and desire to isolate the substation from the control of the despolchcr at thc main stationy he operates safety key bS, which opens the circuit 'for relay 67 and diverte the despetcher control( to the signal bell 14.1. therefore.v the despatcher now' dials, the bellv l rung to Warn the inspector at. the substation. The closure of the iine loop at telephone A operates-relay which` contacts titi closes the circuit of bell let-l over contacts G8, 142 to Warn the inspector. The inspector can at telephone Bcarry out a routine test of the equipment by dialling the numbers allocated to the starting and stopping ot the generator and to the voltmeter and aznmeter supervis1on, and then noting if the apparatus responds correctly;
Switch F can also be arranged so that should something occur in the substation requiring the despatchers attention, such as a tripped circuit breker, an overloaded machine, or other irregular occurrence, switch -F will immediately commence stepping to signal the despatcher. The warning circuit is arranged so es to loop wiresv98 'and 9i) thereby completing a circuit. for magnet (32 over armatures 66, '72. TheV despatcherupon removal of the receiver of telephone'A energizes relay G5 which at contacts 66 opens the circuit ot magnet 62 to stop the switch.
Key $7 is provided to enable a call signal to be sont to the despatcher. Depressing the key is equivalent to looping Wires 98,' 99, and will cause the switch F tostep and ring the des'iatcher. Upon the despatcher.
replying. conyersation canv ensue between, telephones 'A and B.
What l' claim is:- y l. ln a remote control system. a controlling' station, a substation, a twowire controlling' circuit between said controlling station and snid substation, a two-coordinate electromagnetic switch at the substation, means whereby saidrswitfh may beset to a selected position' from the controlling station over said controlling circuit for selecting a particular control., :1nd lneansincluding a singlelstcppinr'f switch whereby-after the setting: ot said two-coordinate switch two distinctive trains. of signals are automatically sent trom the substation over the controlling circuit to indicate the position to which. the` said twwroordinate switch has been set.
In o. remote control system, a control ling station, a substation, a controlling circuit b'e-twecn said controlling station and said substation, a two-coordinate switch, means whereby said switch may be set to a selected position from. the controlling station over said controlling circuit for selecting a particular control. and ineens including` a single stepping:r switch for sending two distinct-ive trains of audible signals from the substation over said controlling circuit responsive to the setting of the first switch to indicate the position to which scid two-coordinate switch is; set. Y
3. In a. remote control und supervisory system. a controlling' station, a. substation, a con-trolling circuit between said controlling station and said substation, control relays at lthe substation for effecting: the control and supervision, a two-coordinate switch. and means whereby said switch may be set to a selected position from the controllingr station over said controlling circuit for selccting said control or supervisory relaysi and means including a single stepping .switch responsive to the setting otv llt?
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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2421169A (en) * 1943-07-08 1947-05-27 Automatic Elect Lab Automatic telephone system directed with the aid of revertive audio-frequency signals
US2540644A (en) * 1944-01-12 1951-02-06 Automatic Elect Lab Allotter switch for preassigning idle finder switches
US2589812A (en) * 1949-05-26 1952-03-18 Maxwell D Hoskins Work progress board
US2623164A (en) * 1948-11-01 1952-12-23 Automatic Elect Lab Single channel, single frequency, mobile radio telephone system
US2656522A (en) * 1949-06-03 1953-10-20 Radio Systems Inc Station selector and recording system for radio service
US2674512A (en) * 1951-08-24 1954-04-06 C E Hooper Inc Broadcast audience measurement
US2712641A (en) * 1949-12-30 1955-07-05 Sun Oil Co Selective measuring system
US2726377A (en) * 1952-10-28 1955-12-06 Sigwald M Hammer Remote control for pumping stations
US2748374A (en) * 1953-01-07 1956-05-29 Automatic Elect Lab Remote control system
US2906998A (en) * 1955-08-19 1959-09-29 Bell Telephone Labor Inc Signaling system
US2993194A (en) * 1956-11-14 1961-07-18 Westinghouse Electric Corp Remote metering apparatus and system

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2421169A (en) * 1943-07-08 1947-05-27 Automatic Elect Lab Automatic telephone system directed with the aid of revertive audio-frequency signals
US2540644A (en) * 1944-01-12 1951-02-06 Automatic Elect Lab Allotter switch for preassigning idle finder switches
US2623164A (en) * 1948-11-01 1952-12-23 Automatic Elect Lab Single channel, single frequency, mobile radio telephone system
US2589812A (en) * 1949-05-26 1952-03-18 Maxwell D Hoskins Work progress board
US2656522A (en) * 1949-06-03 1953-10-20 Radio Systems Inc Station selector and recording system for radio service
US2712641A (en) * 1949-12-30 1955-07-05 Sun Oil Co Selective measuring system
US2674512A (en) * 1951-08-24 1954-04-06 C E Hooper Inc Broadcast audience measurement
US2726377A (en) * 1952-10-28 1955-12-06 Sigwald M Hammer Remote control for pumping stations
US2748374A (en) * 1953-01-07 1956-05-29 Automatic Elect Lab Remote control system
US2906998A (en) * 1955-08-19 1959-09-29 Bell Telephone Labor Inc Signaling system
US2993194A (en) * 1956-11-14 1961-07-18 Westinghouse Electric Corp Remote metering apparatus and system

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