THE BELL SYSTEM TECHNICAL JOURNAL Functional Design of a Voice-Switched Speakerphone by Wf EFMENCY ant WD, COODATR, TR (amispt i der ser 1) Asem har foe thon, Hanon ns he 8A Speaterptane Syn Ye ewes. 18 pravac, ty mateo ll gai ches, cll sme ete da fm datavtend aloe orks ae rging. he gsr-sviehing tion af ining oF Becking—olecsobin ieee twos eft sive et en coo 6f gai. The swig tsb Severed avtotialy secret am nae to wd Ie sno ehasneh, Perfonnan cha emphasis sng ies he paraoitre chosen Iormvmiesajotive er! le agent pe "The orginal 18 Sperzeepkome Syetn? vl swplitcation in both tt receive and srs ala to enmaprnsute fer the acoustic Kha {ra intrortse! I plasing talepone leant a grater Uiurneus Fens ate Chan Rk nenrn! ith a bande, Arion the cperational di fiutce! nih nds 9 sjetens tre talks sho andl aging, parbielaly fuer neers room serie "Ms av the ition hn a iene i the igh gen in oh two Ieasamigeon cbmc, She voionewitched. 4 Seakerpone Sysben baa Sern desgood. Temp rhe gals ia wich of theta cack sername th ho eet of tho str ne ‘gual, Voieositching ferhniques avo ben ese hefeve in capi taneous 38 of aay mis ayers nucusieas 1GHRAD, M4 100 tion equipment dave ee fre se Fino He Tloseres, Sp eppleasion of cert design prin’plat the sere coi seven twain suhetankallyeinater talker she ad ging, feed erty redtesobjectnnable weer the ype aie an fined whl eos eter, Moneever, these achvactuges ace celle for ie ge rondtngs, Une apes eitened =o orovde a tunetia eacrpuon of the 24 Speakerphone Sys nd sh ile perfor ane thesacteritce, wich pacieuke empleo ils a spect scther sungent perfertance objet Lor: « crantnisiv: sluopeind oe foanlamiensal dienes beeen a speaerphors ond» bib! telephone ie che clatsree berean tee instrumner'saal Tye woe Th ein oder in thereeive and teananit dhuirek wilh orwml aitangermute ankiiswred for tho 2 speaks: hon amonnia to come 202 in exh Uhm, ho erat tin Frnvie i each channel to eempecstce far Tis br, wu ths veers fonplnge Denes obo cndapeaker wid the miarophare, iamoduoe fone oprnotiona diieatess fe) onload Sovtuck st singing, <b) xara fohors med to the dik ler, () “ected levels offen feline neg, ad f€ higher usrswived room nese, Waile waive Soitching ia efesive coats lly © nad ng the Giet 05, poe tm ig toza te ater ie ie? ‘Phe tee secs ie which voles etching applies asa slscie= axe inuslew al in igs whic shegs anomie ead eletre lovee or tho 30 Iie a telephones, whan Ley é2e produsing oysivilent cranes Ievele* For she sncegion! nein sie heel and yd Dale Teeter ian, ll Se esl Waly ot che apap franemiting, fig. (2, he seweie dhtone # abeut 24 db above the speech presige a2 the mivraplione. ui ie racaiving Hig ie) tbe evn gebo to he teloorns Hine besa 20 dh abe he ier fech lorel The colitis” evn, nol eingug, Uk Ue gia ey Pehl inj el singing, the stare talker echo 1 the couresta Ieuhore wigs! be eajertenaate om leas oom ‘Th gaze age thar, 90 oe fui ee inary i eta hanya rexponto to sgl fie, uring pros god Is Pini tend ales eet ont be tleablefor tu eelested erdtiont 4 ie geet th the anya nae ad cg os ne sitar aa area i ce Pe a ed Acai, lovnine lw aprekeraboue’s peremance is amoe ep on ues msi al gus ois Pn He Beat of « hae elerane, {reine Une 33 AU oof a wc ene eee ceca In tas 8 Specke-shone, she fray of gn Ienca Uhe 908e and wont chatmele eerie! hy ool ina aperaing on a ket figsreaiel isis; hea che ured having Ie slevager sigaal hos the higher sun, Te prada erccth ein hangs nhs Sotionble cpp sche sponch elaioe and sito inlrferesve oye eapeeced anges fi nsomng ine nee or sous ois he perp, Ke eat) ad the varie gain eres as vetally es pe oth tans da sleady-siate bus The dane fuse of spend, coutiusd Lai, ti, an msn seat Ys all be eon dering, he sopmuprvce sre acai Tn order to reduce the objectionable fete wf Ke yy egg the 3A Spotkecphame ites coy rhe aman gain tha see "ot lub the oigvaher vii dived by ke Heteer. his mean Toa a T-neesunesons or whi the val ete setng i a, ‘anal emount of gain i swiehad ou higher eounestiensregulcing {higher volume ecstrl sotiag, » greater amount of wn is ewiteed, ‘Automari vention ofthe syithing tvosho.d of the onenol eet fn aeerdanos il nay ive te spestereene, by we Hawking the receive cheunel,elininasee dhe seed Fur ny ava i the ie aller or ers Abn hy penper seloston of the Fine constant and th tno ofthe fare eal Genny Ane oe ad a sane fc nn a romaine sn ves ns ‘Brfore describing the voioe switched quin cies i deta, a broad fverall piorme of the erut. ané its operation ie precnted in the fehematin of Fig. 2. ae teanem ekannel ernest of tho reo phone 3 Aumplifers yp abd iy ad the tanent waroleser 24 The revive ‘hanseleczabste of the coudspeker s, anufier an ad reelve varu- Tessar avi. The to cheonels are coupled a tas usual way wet a hybrid teil roe telephone fie he Bakawo retweore nul te Ryd tore pornos curans-esstive wucnble elerate wich wie the devesenee of the op direct einen on the dalanee won Uae ees] ot oc vont pacaly foe elifrer ne igedarces, YVarohwerts Tri ard art. ere varablo-gnin eevieca aegalaved im a complementery miner Uy te dwt eurront lowing throug Uren ‘Thin denon exzsne is e2tained fran the ancl velaane wel von, sive tom the sombiaatioa ef eatrol exp ier a zee cy and tine Ing ezeuit fp. Tho input too he meroaome egal taken moet she tutu of acuplifer age and ready Mi cule runser sie An tnetesee in tho diet earront through cer, rabies tress il se Te “sie gin ini, esting f empl dg rece me, alsin, sent prindures a dive cent whieh ine aver te le of 72k rsponce Co the valtage across the loudepenke, ides gute agitate evteing of the rosie gral Use to th micwphone voltage rsu:ing from the letdspscker euspst. Another Aiyet curse, 2 pavdised by the Naeas* from any nearly conse ‘nisrphiene voltage dis tothe nose ae tae speskerpboneloeation, poate eae operated pia adjating devo. vere wemeue arsaniaeuonie osu ‘Phe operation of the winston einai re by expla by siding ever nie Fest fe ince erin of no Yea spe aim a ero phone and no isomig Fgh rn he Line. Nie ar los eo the nina oer ne nosh Te ad RP aula Hee eucra fhs Urew evn frome ey wr eg, Comequenty, the guin of the reeers lil ehh wed ta of che seas hue ia low." spe ‘Thee f thie smn fr leuiboerlcreopendntion of ne wane of sang Ie ‘Second. ony 9 line eaue) is preseut wud i being epeoduced. by the lwidkpenlor. Tho sainehgonrd ae » pelt of the londepealor voltage, notes the Inge uxt Lins the Spit to ae reeultiog om ihe woe wanting beswten the micropkoue end che loadeptae, 20 hac aint fs Prebion! Heo we nd we. The were chee scaling i te high-gain ata, allowing mnineerpiedInudezeaker ere tion of the inersing sigzal, “Thd, sol pee We eerophone with we coom noise ad nn in miag tgual. Ne dirce: ewce:frem 1g and ay ows through ees ‘he os of aye ia emupled ith auinciam anf 77. a erie sews eunent fm sc to flow taugh ret and ave. Zhe gin of the tanemit chanel ia high ead thaeo tho rovivacicanel ia Wo, et cee at the rreraphone ic relly sronsittd #0 the lin. voi sa rand nso eth os i he iano om nasa ch sieophnss. Toe Isee of ern intend hy le fear from the stun, 96 tae oe nue gus) st the imp of reduce only small currene rough seu und wre, Local seedh, bow ever, dove ot eause an saerece of tho drset euzen: from the soa, erase fb signed lo alo pense vo Euctuting ign ‘Tre lnemsaual lm sev Su ha the nese the meropenem, can be uveroome, hexevtr by cho hor ve of speodh signal morally [eco nr ta evan ack oe sgn om eee The inp eas #0 thal ce ulin eer rhe Ce ee sand vt clone the store cane ad Wives ae seni shan if vs signs is prose ad goers noise exes atthe memphis, Teli 2 suuap aad the avitekeuord oroduep dicot eugene Cy and in nemo eve qevents eetve blanking secu cf 250 oF fecial's ap ng belme lleker al mrophone, ‘Sir, cn ineoning speed) sgzal is wresere ex looal speech exist the sieraphene. Dirert curr iene to o6-from the eétabeuard, ca mig ge extn tthe niga hays Uo nel the lseepisrn, The sslalive gual erengit= nee enna fw eit the svi eu eeeiges 1 rhe area he ot wil taster to the ly th nag eels ee e= Ja sal“ ere eng, the enol at he whoplacue is are Aull age oft Iovsr fpr thet i eurtivnuely ay iteing hetwers the anenit sl aeeive states, 9 Ph iter pasty eam ley weet Ua ver Fn the otter party The vrielbesrs mvt anda the eis ane mane charset br gnc ie thoee wed nthe corneas of everiee aslo Ln the peess:t applition, the varile jmpodiiee element iw dite siisin vetiste, the ae estan of whic vies nerdy a mel fnf contivnos manner ss a storian of hs inset arr hong i Fray an bes in Fig. 2 Ue nari ae ath ewes a {ie ens nny dats ears of Hh impedes ba Ince Monier cures inercase tae gain of thecal 6 the waianes ate part of che akoxe pech, and e deere of di hone ‘levies ky an Hated toe of ineet current desreass the gaa. of the tvreirm channel, ‘Th charecasstes othe volo wns ane sin a Fg 8 Teche range of net current provided bythe woptea rectfer me fu the volume contcol vou, tas chenge ot gui of 88 db and iat ff ani 42 db. Haass tho sare worl ware Fears eg the tals woe hele lll the selon, Ue gine alae thug i 8 omplerentey reannen “rh saris tsi ch ace aboot ath, ant shown in Ws whic serves onal he fon sana. Ashen in Fg. fe ats of the crane ad eee en eg ie vassal an Hi for fee coment. This evids peels sia for wd — of 6 rr ea, ave rectstnas MOOBNADS MAT OAL sy vetGng the vole eousrl wid a the alte ra geo neo Sve act vanes wath epece level "Becsoe che vivian art male oiouitalaens etre cast: be tain ra minindee eet o nals a Hae varolocse, Inthe AS Speakerphouo, the egcal Levala have beon juste sn al the fda Fr Tinerity team over the rare Sguokecueumie ato tae ovelned pointe of ho dapliiom i eal shonnel, Tusthormory she saxolssers re aerane os Fes et fo keep iin warrent wararons fiom prodiing nurterenee oF ‘df he apr che Tn ciiien co the carn foam the emir wets wo, ce louse sqvaker volume vantral vor sujotiee to “he varin‘oamas a quanity of dich cuteat depetient ils cal tetting, ‘his oon Te at Jn ig, vase yin othe toe sel sel alo yree Waa ‘nuzen: fron wih Ie sto ene saerestt it nannies Uo ere al the microshunc. Ts saul:g effect in that the arian again Steed hy ule erent gs esl for she ler vile rel Dositigns sd Tewnvs glen ae he were eu i ule’, a portray i Tig ‘On thes wary of ells, ook x still asm: of gan i ated, ‘Woon le Yosome contol eoiags ioe lupale Ioudepenker cutpu. ea vere nd solu eames sor eEEROROM ft ‘Ag wren, scusltonents sivas ie permed ith Pansy moieeeble ‘ping vn lsc ges he Hamieelbaegrond nee, emg Som the yi swlleLcngy ate sok spparert a2 the eonnertd toenhon. ‘lowers, wfice’ ee a eviebed ey that the tc eor ecb nant i roe oljertimele, even for raaderately reverbensrt mons, Ov slay cller bal, shen te volne contol in nope ies rescirowm ton Tigh-eascomnesinns, the renlng Voie switching auc xo Rawr floes mon notivenhy lt endo be tasked hy noer a th dist? tu, eave of Or eer erie ge ser. an eh onve)inbsassions, th oomtol pec the switebgeacdl pac, tuud teeta sfvas nal Ihe Hace of ee env i regents ial ow in is sqm sbounnl, In te abeezce of both, selva Signal and aur ses sin, speech sana frm the meen pose ‘Bough evi ath vuniownr ham ler anplied Bye eid bp toy vl copmsel ting ibn. Whom the voltage deve:oped Diy wes binge hn Inia age ene with ta ete av, ete "i bi ar Pigs tno lw aya tran ating ea sleviatie moameed With LOD eye eight. cron Ue wiroghoa fr YFaicus volume tarine, pst fers les. hy svildian’ ed one ‘drouie ere invetive A the masininn: volume sesng, a gain change of BT UU evry as ln tnnplnne velagn Vy wares fram —87 ta 81 Abe, A awer sng Lhe yi shange ete, bn Les pei at hia tating is estpled yee he reme, ‘Wier n udipealer vollage ie present, the rected oxtpu: of the sevilla rhage fh ee of evi provorticr 30 she Tourer voltage aver a we rang The iain ml nf Ue ea eel ‘wth ludeseaker vellyge Vo 20 slay aul the Secun inasive Is show in Tig Teasing thew deta, Li dst pach 2 inverrapted EU heingu of aviond pipes omncnatone etrarbed, zesivig sual to pnulace Fs ose tye pak ef a2, Lana a owe mophore sulage snap ata inky ‘teased, Ata vical vale o Fy this fuse = diy hw pain of the tale channel abrupt cereus Sinniuavealy, lve gain of the sovive ebennel, aa skowu ia Fie. 7, abraply deen, even taloc Fn avd eva Went aie gn Uae deli aru hr eae, 370 lene pin, ede Mirek yeti ta ho tate, Fy BML he reduced eoasiesubly belo Meee oal sale, eons Te setanra Toei ov emaing fromm the BS ue wuLL erscioe shortest somevaty MAY et lover hase visage at the input af the sitcheuand Ata seu lia slab? Vig, i thie ccee aly, tae ect roturas to he ev sate, The veloc of Yay determine obo 70 » sail goin mith F = idly. The hysteeae foe: hele teints'n one dewaion gos il a Be ineerval ewe eos ue ee 000m ie the sgnale psig rough toe sgn sing Tae higher pir a rani a delertes attempt i nl ta interstory ie signed Irvolis the eer share, The wnguilude this heetnwsia eters depends tin The wr nfs se rc corned he th woh unt ‘ering ‘The 10 1 snot fury of Fig. 8 ahows cho vltisueip bebnern Vega ya te ris oe. Orme a tenga of ele Ee zeta