9so,a59 •.
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`·.:MULTIPLEX TEL~PHONY AND TELEGRAPHY .
`. APPLipATION FILED NOV. 6; 19l0.
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`Patented Jan. 3, 191li.
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`Ft:J.2 .
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`r~.~ . ·.
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`~t _:..._s
`lAJ
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`Cisco Systems, Inc., Exhibit 1008
`Page 1
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`UNITED STATE~f-PATENT OFFICE.
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`GEORGE OWEN. j;;QUIER; OF THE UNITED STATES ARMY.
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`MULTIPLEX TELEPliONY AND .TELEGRAPHY.
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`980,359.
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`Pat.e~ted ~an. 3, l911
`:~p~dticatlon of Letters Patent..
`Application tiled J:<ovember 5, 1910. Serial No. 590,804.
`(DEDICATED TO THE PUBLIC.)
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`30
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`! Reference is here made to my co-pendina
`To all who·m it ma.y concern;
`lle it known that I, GEOIWE OwEN SQUIER; I applications, Serial Numbers 590,801 and
`major in the Signal Cotps, U. S. Army, a &90,802, filed November 5, 1910, in which I
`citizen of the United Stutes, and residing ' have discussed at length the advantages and li5
`limitations of the use of electromagnetic
`5 at\Vashington,DistrictofColumbia, (\vhose
`post- office address
`is War ·Department, waves of various frequencies in such systems
`Washin!rton, I?istrict of ·columbia,) have as described there and here. In accomplish(cid:173)
`ing the desired results, I h~;~.ve found it ileces-
`invented certain new and useful ImprO\'e-
`~. · ments in Multiplex Telephony and J'eleg-
`sary and sufficient to combine the engineering 60
`10 raphy, of which the following is a specifi- 1 practice of wireless telegraphy and teleph-
`ony with the engineering practice of wire
`cation.
`·
`te.lephony. I
`This application is made under the act of
`telegraphy and
`haye al.so
`found _It necessary, m order to obtam sabs- ·
`March 3, 1883, chapter 143, (U• S. Statute
`·XXII, p. 625,) and the invention herein de-
`factory results, to make use of such detectors 65
`·15 scribea and claime& may· be used by the as are commonly found in the wireless tele-
`. Gov~rnment of the United States or any of . graphic art. Attempts have been made at
`its officers or employe~s in the ·-prosecution multiplex telephony, but I have found these
`-of work for thi:! United Statf•<; or by any
`inoperative for the· reason, among others,(cid:173)
`person in the united States without the pay-
`that-no detector or equivalent device has 10
`: .2.0: ment of any royalty thereon;
`been used. These detectors are not used be-
`'!'his. invention- relates t.o multiplex teleph-
`cause of any greater inherent sensitiveness
`. ·
`ony !1-nd telegraphy an~. !1as as its obj?ct 1 to electrica} en~rgy than resides in the tele(cid:173)
`phone receiver Itself, but ~cauSJ:l the energy
`the smmltaneous transni1sswn of a plurality .
`of telephonic and telegraphic messages owt· being in the form of rapid oscillations can- 75
`1
`· not affect the telephone ot' other conl.muni-
`25 a single circuit.
`A further object of the inn:ntiou is to ) eating device; These rapid oscillations can
`make.use of grounded or earthd •:'->Dnedions not sensibly affect the telephorw, because the
`in combination with the usual metallic cir-.. diaphragniin its motion must reverse with
`cuit.
`the reversal of the current and the deflecting so
`. A further object is to rcnller such a system
`impulse if applied diPeCtly to the telephone
`receiver will be first in one direction and
`as the above Silent to external disturbances
`and in such manner as to eliminate all cl'O:c;.-;~ . then in the other with a frequency so high
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`talk or harmful effects of one Hwssage upon I that the diaphrag. m cannot sensibly follow
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`I an impot·tant pai:t of my invention. to make
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`or respond. Furthermore, if the diaphragm 85
`·
`·another.
`· A further obje~t is to apply electri~ waves 1 should respond wi~h this frequ~cy the effect
`!5
`of su~h frequencws a::; t.? lllake pos,;Jlo1~ ihe 1 would ~ot be audible. Also m the case of
`sel~twn and complete mdepend<"nee o:f tl:re 1 the ordm~~;ry telephone, on !lccount of the
`various mes..c:;ages.
`.
`.
`large self~mdudauce of the mstrument, th~
`A further obje<:t ir;; to superimpose npon high frequency E. M. F. generated by the 90
`.(0 a standard battery telephone eircuit, m; uow waves would produce in the telephone re(cid:173)
`commercially in use, one or more telepbouic cei~r only extremely weak currents. I have
`and telegraphic circuits without any inter- 1 found it necessary therefore, and consider it
`~erence of the nrious messages. -
`·
`11se of some form of intel!t'll.tin~r detector to 95 ;
`In accomplishing the abo,·e res.ults us<'
`·45 is made of electromagnetic -\nlVes, or ~sci!- I transform ·the rapid oscillations into 'effects
`lations, ,of· ~gh frequency, prOJ?ngated- l?.v! ~Yhich can be manifested by the indicating
`means :of Wlr.es, .and_ whe~;e use 1s mad<~ m 1 mstrument.
`~hi~ application of the term high frequency, j This application is closely related to my
`It Is .. unden;tood to mean n.ny ultra-sound I three co-pendi,ng applic-utiom;, Serial Num- 10c
`50,:fr:eq.u~n,cy or frequencies above the limit of j hers 590,801~590,802, and 590.803, filed No-,
`In each of these, use is
`audttton.
`• vember 5, 1.,910.
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`Cisco Systems, Inc., Exhibit 1008
`Page 2
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`made of high freqlll}ncy waves as a vehicle I denser _C', tl~~ being all variable and con(cid:173)
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`'dB0,369
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`15
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`the' telephone ·or telegraph messages Bected In &:;nes m the sam~ manner as show a GfJ
`fur-
`whi~h are impresse? upon the same line ~s at the !'tatwn B; _Inductrv~ly co~J:ec~ed t~
`carries the tclephomc cuiTents from anord1-
`IS a recctver cucmt R,
`the pnmary P 1
`5 nary local battery ~elephonc. set..
`.
`.
`.similar in .every respect ~o the rceei ver H
`.c<J-pendmg appllcatwn, &mal at the statron B.
`In my
`Inductively conacctecl to
`Number 590,803, I have shown a specific
`the second!lry S' is a transmitter circuit T', 70
`manner of ~nx:-ect~ng a plurality of high s\mil~r in .every res,rect to t}•c tran;;mitte~
`.fre~uency Clrcmts ill parallel between the CircUit Tat the station B. 1 he rccetvcr n
`10 :ordmary battery line and the earth. Inthis
`is. tuned to the £requeue;: of the oscillations
`application I sha_ll describe a. ~ahner of con-
`g1yen o~ b~ the ~ransmltter T and the rc(cid:173)
`necting a plurality o£ such lugh frequency· ceiver circuit R IS tune~ to the frcqueney 75
`circuits in ~ries relation, making use of. the developed by the transnutter T', these frc·
`telephone circu~t and gro'?ld connections. .
`quenc.ies being ~ufficie~tly different tf! afford
`In the drawmgs formi!}g a. _part of tl~IS effective, selective tum!1g .. Th~ tumng e~e·
`specification, several· modrficat.wns .for cir- ments throughout the Circmt. wlnch compr1se
`cuit connections :are shown, and in said
`the various con'densers and inductances are so
`drawings, Figure 1. illustrates a circuit in ·all vatiabl~ in order to permit of ready and
`which a pluralityof transmitting or receiv-
`effective tuning of each and any circuif.
`20 int; circuits is connected in serie~ in a ~ir-
`. The high frequency ~ransfor?'ers are a!! so
`crut bet'_Veen th~ ee;:-th and the or~mary tele-
`c~mstructed .a~ to gwe v.ana.ble ~o~phng,
`·phone lme. Frgs. 2, 3 and 4 Illustrate a
`erther by shdmg the on~ coil wtthm the 85
`·modification of Fig. 1.
`. other, or having one cog !iwing within the
`Referring to these figures in detail, Fig. other, or by any other suitable method well
`25 1 shows a common metallic circuit A-A/ known in the wireless art.
`·
`fo~.ordinary telephony, across which. are·
`T~e operation o~ the syste~ is.as foll?ws:
`bridged the t;elephone sets B B'.
`T~e;=;e Ord~nary telephomc comml!mcatwns may be 90
`telephone se~ mclud~ the usual.app.aratu~m carrted on between the ;rtattons B and B' by
`present use ill local battery circmts, there
`the telephone sets. Stmultaneously there-
`30 being shown a tr~nsrilitter 1 of any suit:r!>le with high freq~ency ,oscillations may be i~­
`form such as a miCrophone transmitter w1th pressed on the lme A by the transmitter cu:-
`its local battery 2 and tlie· prim~rv of the cuits T and T'; both of these operating at 95
`transformer 3. Also there are shown coQ.-
`the same time, if desired. These high fre(cid:173)
`nectec:I in the usual way:the ringing circutt qneucy oscillations are modified in ·accord-
`35 4, the switchhook 5 and the receiver 6. The ance with· speech by the microphone M, and
`~condary of the tr11nsformer 3 is b~idge_d oscillations. transmltted by T ~re picked up
`d1rectly across the line when the receiver IS by the .receiver R' and are rectified or trans(cid:173)
`off the hook.· T~e inventio~ is not ~n any f~rmed by the det~ctor Din such~a. way as to
`give a reproductwn of speech m'. the tele-
`way connected w1th the details of thiS tele-
`40 phone connection, any llf the usual circuit§ f phone F, all of these being well known in
`being suitable,- and the one described being
`the art. . So also oscillations modified bv the
`given merely as an .. illustration. Coriilected microphone Mat the transmitter circuit T'
`to the line wire A', at or near its connection will be. translated into speech at the station
`to the telephone set B, I have shown a cir- R. All of these mes8a,ges may exist on the
`45 cuit connection to the earth atE, this circuit sameline at the same.time without any cro!;S(cid:173)
`including ~he variable. inducta~ce I, the~- talk or interference w~at.soever .. If desired,
`ondary cml f-;, the pnrnary o01L P, lllld the one or more o'f the microphones M ·may be
`variable condenser C, these .all being con-
`replaced by suitable telegraphic keys in or(cid:173)
`nected directly in series.
`.Induct_ively co~-· der tha~ communica~ion by U:legraphy-m::y
`50 necte~ to. t~e s_eco.r:darx S IS a. pnmary cml · be earned on. 9b':wusly this change will
`P which IS IO cir~mt }\'It~ the hlg.h freq~Iency not affect the -prtilctple of the opernt!on. in
`gen~rator G, this. Circmt also mcludmg a any way whatsOever. The· telegraphic sw(cid:173)
`variable condenser C, and a microphone ~ nals may be produced by the ordinary k;y
`!ndiJctively conn~ted .to th~ pr:Jm:try ~:;
`'Placed directly in the g~ra~or circitit or by
`55 IS a secondary coil S, mcludmg m Its c1r-
`such an arrangement as IS shown in Fig. 3 of
`~uit a variable condenser C" and a variable . my co-pending -application, Serial Number
`mductance L'. Shunted around the 'con-
`590.801. It. is to be noted in this circuit
`that I have cohnected a. metallic circuit to
`den!ier.is the detector D, anQ. operatively
`associated with. the detector D is the tele-· . earth at both ends, and I have done tl1is
`60 phone set F, Wit~ a bn.,tt~ry jf .de:-ired. At. I without experiencing any difficulty in conse-
`or near t.he statwn B
`I am able
`to accoin~lish t_his by-mean~ ?f the cond_en!iCI'!i
`'co.~nection, Jncluding the ind~ctahce I', the
`p11mary P 1
`, the secondary B and the con- C and C , which, m additiOn to actmg as
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`IS a stmtlar earth l quence of external disturbances.
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`lO(
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`lOfJ
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`100
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`115
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`'120
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`125
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`Cisco Systems, Inc., Exhibit 1008
`Page 3
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`95
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`980,359
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`a.
`tuning eiements, also ad us a eheck to nny acToss the lines A A' which sene the pur(cid:173)
`eal·th distHdJallces in the vieinitv. This is pose of ph11·ing the two lines A aud A' in 65
`po::;siblt• onlv bt•<·aHse the <:lliHJer,~;·rs {' :~ud pand!el fm·
`the high f1·equency cmTenb.
`C' here wwa nre of VE'TV snwll el·•etrical di- This capacity, howen•r, is made so small as
`5 'meusious, being l!ll~USl~red in some thou-
`to giYe prncticnl!y insupcraLlc impt•dancc to
`sandths of a microfarad, whereas the con-
`t!te telephone currl'nt.s of ordinary frequen(cid:173)
`cies a:> ~in-n by the telephone sets B and 70
`uensers now iu ordinary use in telephone
`pradic~· lun·e u capacity measun~d in micro- B'. It rs idso olH·ious, as shown in Fig. 2,
`that high fre(l~ency. currents may be con;
`funds. Such large condenSt•rs otfer very
`ued('(} to the me wtrc A 1\S shown at T'
`10 Sluall impedanee to thP pass<l[rl' of extemal
`disturbances of sueh
`freq11encies as ar.e
`and H", thest' ('irtnits having connected in
`within the audible limit, but with my very
`them n plurality of transmitter or receiver 75
`small cOIJdensf'rs and sharp tuning in the circuits in auy suitable arrangement.
`ground (•ircuit to a fre<juency enti1·el:y abo,·e
`Fig. 3 shows a further modification, which
`15 autlition, these low freqUPIIC}' audible dis-
`is a COntOill:lfion of the systems ShOWn in
`·tur!Janc<:s are entirely shut. m1t, .giving ine
`:Figs. 1 Rnd 2 a.nd the li,Ystems shown in my
`co- pc11ding application. Serial Number so
`what I dwose Y> eall a "silent gt·ound con-
`m·<·tiou ". In Yicw of the fact that hereto-
`this figure, a plurality of
`590,802.
`In
`fore ;;ing:le line t!'!ephone circuits which in-·· branches ('Onnectcd to the earth is shown;
`20 chide a ground retum, or u ·2-wit·e telephone each circuit includin~ a plurality of trans(cid:173)
`(·it'('Hit- \\·hieh i::; grounded at either end, .are mitt('r m· receiwr circuits; as shown in Fig.
`suujeet to n~any and strange noises, the 2.
`In addition to this high frequ~cy trans- 85
`eauBt's of which are not entirely undet·stood.; I mitter cit'euits .are inductively connected by
`cousi1ler that n(y present invention, whereby means .of transformers co1inected_ directly
`25 I a111 euablcd to nse ii ground connection on
`in the line circuit in set·ies with the battery
`sets B and. B' in the manner described in
`a sin~le telephone circuit with no sueh dis-
`tut'llauees, a vet·y important and essential my co"pending application, Serial Number 90
`par-t of my invention.
`I have found -the JifJ0,802, cited above. In this case, the con(cid:173)
`above cin:uits entireLv successful on a stand-
`dt•nser-s K and K' are necessarv in order to
`.lO ard tl'lephone line circuit consisting of a. [live a ft·ee path for the high frequexicy os(cid:173)
`pair of twisted copper eomlnctors, pitper in-
`cillations of the series connected transmitter
`sulated, which pair con~titutes hut ·one out and receiYer sets J.'' and R'.
`.
`. Fig. 4 shows a further modification. in
`of a l.·arge number iuclo~ed in a lead sheath
`in ordinarv cit.y .. traffie. This lead which the batterv sets B and B' and one of
`used
`tl1e line wii·es s1ich as A, are entirely elimi(cid:173)
`::!5 sheath surroundii1g the pair of wires br·ings
`t)Je earth cormeciiou \·er·y dose indeed to the nated; in whieh case I have multiplex tdeph-
`Jine <-ireuit ali along its length, but in spite. ony Ly a siugle wire using earth retul,'Tl. _100
`of this. m,v selec:tive ein:uits an• ,.;u eft'ective I As is appar·ent ·from this Fig. 4, I ha,'e
`a,; 1u gi,·e no traee wha.i:-;oe'·<:"t" of <l.H)' eross-
`shown a plurality· of ground bnmches, each
`ilH~luding n plurality of telephone or re(cid:173)
`-lO talk or inHue!I('C clue -to cxtenwl disturb-
`It i,; appa!'('llt that any number· of ceiver sets, each transmitter having a differ(cid:173)
`ann•s.
`transmittt•r or ren·i\·cr eircuits may be con-
`ent frequency and having a receiver set at 105
`the other end Qf the line tuned to its perio-
`nN•!p<) ill S(•l'it•s in addition (O Jhe two shown
`ill Fig. 1.
`dicity; Also in series with the line, 1 ha,·e
`·
`·
`Fi!.!. 2 shows ri modification of Fig. i, in conneded other transm1tter and-
`receiver
`whieb a. plurality of earth. branches are con- j sets, as sh?wn diagran1matically at 1" and
`IH~'tl'd m parallel. each sm4!)e branch eon- · H'. In tins case ·r a.m able to carry on mul- 100
`JH•etl'd to e~t1ih being simifur in every re- r:iplex telephony by the single wire· con(cid:173)
`l-'P<~"t to P1e ea1th brariclJes shown in Fig. 1,
`1ected to earth Rt various points without.
`,,o :•lid each including two or more• circ.uits any cross-talk or disturbances from extemal
`· cau!;€s, and I co11sider this au ~ssential .part
`whieh may. he transmitter <)r receiver cir-
`(·uits, the.w cireuit.s being indieated. only of my invention. In connection with Fig. :1, 115
`diugt·ammatically and designated by the ref-
`I have shown means whereby :Morse teleg(cid:173)
`raphy .. may be carried on in the usual way
`'-'reuce <:haracters T and R tln·oughout. The
`u5 com1eehom of the hatterv sets B and B' are
`ltnd ·this without any cross interference of
`~hown only dia~rammat'lcally. it heir~ un~ the ine.<;.<;a<res .. In case way st~_tions are used
`d(•rstood that the· connections nrc similar to on the li~'e, each of such $tions will be 120
`those shown in Fig. 1. Ead1 transmitter shunted by a small condenser ~or :i. con-
`hns a diffet·ent hequ~ncy always bQin1-' of denser and inductance· tuned· to the· fre- ·
`GO tiltl':l-~·:otmcl frequt•ri.cy. an~l ~aeh transmitter cmeney of the high· frequency oscillations.
`lws a ('O!Te~ponding receiver ('ircuit at the Thus it is appat·ent th;r.t my inventio~ may ·
`Li~ ~:up~~rirnpo~ed dircct.ly on the ··pre.c;enf ·12t
`< tlwr· <'lHl, of tlw line tuned to its frequerwy.
`I may al[o;(> u~e> e()nden.ser·s K aml K' bridged J l\f01·se telegraph >.ystems. Other forms of_
`
`15
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`Cisco Systems, Inc., Exhibit 1008
`Page 4
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`980,3{19
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`-·r:._:·
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`f .. ·
`· ·
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`high frequency transmitter and recdver cir-·1 cei n~r circuit being tuned to one transmitter
`cuits m:ty be '-!sed in pl<!Ce of "OlOsc shown,. circ:uit ~ml c~ntui_uing a detector for ~igh tHi
`and vurwus RUitable moddicatwn,; are .showll herjuency osc!llatwns and a telephone r•: ·
`and described in detail in my co-pending ap-
`ceiver •)perati\·ely assoria.ted with paid !;(·-
`5 plication, Serial Number p~o,$pt_cited a bow.
`tcdot·.
`.
`r.. Iu a mul_tiplex !eleph~me and telegrll'vh
`Al~houg_h sever:al. mod_lficati~ns ~?ve l~ce_n
`descnbed m detail m th1s spee1fir,atwn, It· IS
`systc:w, a pa~r of hne w1re_r>; ~attcrJ-: tele- 70
`obvious that many changes may be made phone sets br1clged across saJu ilne wires, a
`without departing from the spirit <!f tlie in-
`plurality of_ earth connections. place~ be-
`10 vention and I therefore do not w1sh to be
`t;vecn each lme unci the earth, a plurahty of
`· limited 'to the exact con_nectio!'ls s~wwn, but
`!1igh !regnency signaling cir~uits a;;sociated
`\Vhat I claim as my mventwn Is the fol- m_senes.m t:;ach carth~nnec~10n,_ea.ch traf!S·. 75
`lowing:
`.
`m1ttcr c1rcmt developmg o~Illat:ons. of ~If-
`1. In a silent earthed rnultrplex telephone
`ferent frequency, each receiver c1rcm~ Lemg
`15 :md telegraph system, a ·]i ne ~vire; a plura,I-
`~une<l to one transmit~er circuit and ctmt!lin~
`ity of earth eircuits exten.dmg from ?aid I~g a detector for lllgh. frequency. osCilla(cid:173)
`line· a plurality of transmitter or recmver hons and a telephone receiver operahvely as- 80
`circt'Iits associated in series relation iu each
`,:;ociated with said detector.
`7. In a mul.tiplex ~Ieph~me and telegraph·
`of said eui·th circuits,· each transmitter cir-
`20 euit impi·essing di~erent · but u~tra- ~oun_J system, _a pa~r of lme WirC?, b.attecy: . tete(cid:173)
`frequencies on the hne, each rece1ver Cll'CUit phone. sets bndged across said hne wires, a
`plurality o~ earth connections placed be- 85
`being tuned to the frequeney of one trans-
`mitter.
`. .
`·
`·
`tween each lme and the earth and containing
`2. In a silent earthed multiplex telephone a variable condenser and a variable induc-
`25 and telegraph sy;;tern, a line wire;. 'a plural-
`tance, a plurality of high frequency signaling
`ity -of earth circuit;; extendiug from saitl circuits inunctively associated in series in
`line· a plurality of transmitter or ;rccei wr eacJ1 connection, each . transmitter circuit 90
`circ~~ts associa~~d ~n series- rel~tion 'in 'eaeh con_tain_ing a g.en~rator of high .fr~uency ·
`of smd earth cn-e\.uts, a plurality of t-rans-
`osctllahons, a Y:tnable condenser and mduc-·
`30 witter and recei •ier circuits assuciated in se-
`tance for tuning said circuits and a telephone
`ries in the line, each trausmittcr impressing
`transmitter for modifying said oscillations,
`different but ultra-sound frequencies on the each receiver circuit being tuned to one of 95
`line, and each recei\'er Leing tuned to the
`the transmitter circuits and contitining a de-
`ft·equencv of one of the transmitters.
`tector of high frequency oscillations and a
`3. In a multiplex telephone and telegraph
`telephone operatively connected therewith.
`system, a line wire; low frequency 5ignaling
`8. In a multiplex telephone and' telegraph
`apparatus connected to the line, a plurality s.vstem, a pair of line. wires; battery tele- 100
`of ground ·circuits extending fmm said line, phone :-:ets bri<lged across said ·line \Vlre~; a
`a plurality of tmnsmitt.er· or receiver circnits plurality of earth ·conned ionli placed be-
`40 ass9ciated ~n series rdution ill each earth
`tween t~ach line and earth aml containing a
`eonnection, each transmitter circuit impress-
`\'uriablc inductance, and '-·ariable <:ondenser;
`ing different but ultra-sound frequencies on . a plurality of high· frequency signa lin" cir~ 105 .
`the line, each receiver circuit being tuned to cuits inductively associated in series in"' each
`the frequency of one transmitter.
`earth connection a plurnlity of sign:tt11g cir-
`4. In a multiplex telephone an~ telegrapJ:r euits eonnectt>:d inductively in series in the.
`system, a pair of line wires; low frequeney
`lines, each trumanitter circuit developing os(cid:173)
`signali_ng apparatus associa~ed· therewith; a_ cillation5 o_f ~lifferent ,qltra"smmd frequencies 110
`plurahty of. earth· connectiOns placed be-
`.and contammg. a nucrophone transmitter ~
`tween each line and the earth, a plurality of
`for modifying. the ·,oscillations jn accordance
`50 !tigh f~eqn~ncy signaling circuits ~ssociaJed with _spe~£!i, each_ receiver circ~lit_~o~aiq!ng ··
`m seri.es m. ·ea~h earth .conne~twn_, eaeh. a vanable m<lud:nnceand a vanaplecapa~tty,
`transnntter c1rcmt deYelopmg oserllatwns of aiHl tuned to the·frequeney of one transm1tt~r 115
`· different but ultra-sound frequency and eaeh circllit, a detector in shunt to the·con&enser
`reeeiver tuned .to one transmitter circuit.
`of t~1e re.ceiver circuit and_ll. ·telephone op~
`5. In a multiplex telephone and telegraph ei'atJvelv ~onnected therew1th.
`·
`syste~, a pair of line wires; low ft·equ~JJ~·y
`9. ItrZ'a mul_.ti.plex ~elephone and telegraph
`system, a pa1~ of· hne wires i battery .tele- _120
`lmdged a~ross s:u<l
`s!gnalmg apr!aratus
`hnes; a plurahty of earth connectwns pl:wed · phone sets bnd«ed across said hne wires·
`·
`betw~en eaeh lirie an~ the _earth, a J_Jlurnlity
`a condenser of.~small capacity parallel t<~
`60 of htg~1 fr~~ncy s1gnalmg c1rcu~ts. asso-
`eae~1 .of th~; battery tel_l~fJhone sets; ,a plu(cid:173)
`emted m se_nes m eaeh ea_1·th connectwn,.caeh
`rahty of earth cmmedwns placed between
`. t~ansn~itter circuit developing oscilla,tions vf ea<;ll: line and earth and containing' a vari- ';1.25
`able ir.ductance. and a va~iable 'capacity, ·a · · ·
`dtfferent but ultra-sound frequency, each re-
`
`55
`
`35
`
`45
`
`Cisco Systems, Inc., Exhibit 1008
`Page 5
`
`

`
`980,359
`
`5
`
`-plurality of high freqnelll:y signu!iJJg cit·(cid:173)
`cuits inductivdv assuciatetl in' series in each
`· Purth corllll'dio-l.l; a pltmtlit.v of ~ignalirig
`eircuib coJlll<'detl imlucti n~ly in series in the
`5 lines, each transmitter cir~:uit de\'eloping
`electric waves of diiferellt Hlt r:H;ouuJ fre(cid:173)
`qnen<~ies and coutainiug a microphone tL'<lllS(cid:173)
`mitter for modifying the oscillutim!s in ac(cid:173)
`cordance with speech; each receiver circuit
`
`co uta iuing a variable inductance and a vari- 1 q
`able capacity and tuned to the frequency <•f
`one tramHnitter circuit, a detector in shunt
`:tu the condenser of the receiver circuit aiid
`a telephone operati \'ely connected therewith.
`GEORGE OWE:& SQUIER.
`\Yituesses:
`. ·
`P. I. WoLD,
`E. R. Ca.ur.
`
`Cisco Systems, Inc., Exhibit 1008
`Page 6