US1545558A - Tandem-operated echo suppressor - Google Patents

Description

July 14, 1925.

H. S. HAMILTON ET AL TANDEM OPERATED ECHO SUPPRESSOB ATTORNEY iil To remiou'relaiee totronsinissiori circuiis no. more puriziculzwly to treosirussion if we or July i i, iiiilllf i,

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ATE

, NEW jlEIi lEiEii', ASSIGNQES I' I'J JOATEERICAN TELEPHONE AND TELEGRAPH 2', Al. CillRI-'iliiA/EEQN GI! NEW YURIK.

duplication flied .l'ely 2,

To aii coil-0m may concern:

Be known um: we, HAROLD S. HAMIL- won and Stun-mu iVuiorrr, residing at d East Orange, in the coun'lies like; 1; and items oi New York o ere-e ree ociirely, have invented ncrements in Tundei'n llperated nniessors, oi which l'lie following A meat, on.

circuir"; employing echo suppressors,

like of rho oiiieeis of the invention is to an urmingcine wherebytwo or ch eo pod with echo supa l a M rod in tandem. The presented when two or more cirii ire-icing}; an echo suppressor, ore ed together, to prevent the circuits rilaere in; the ends begin to roll: it about w some time, neii eble i1? hear the other The nzilurc of imagine l fli/lilTi O circuits, each eonizainir 'iogoci o. boi'ullr, e "voice currents generated will reuse the suppressor near his end to open etc in such e. way as to Sl"i( 1i)-i)lll3l.lll3 "die trimsmission pail, cl'lining; from. die subscriber at the end H, before the voice currents from iiiie cuoscribcr at end Arcaol tlic second suppressor recur lilie end lifllie sul iscriber atend l3 already started to tail: and the voice generated at his steiiou have caused the o nressor near his end to operate, it will ice eridcnr time the Voice of the suloeerilier .Aik. will ice blocked by the sup- 'ireseor can end while lire s oice of the subscriber in will ice blocked by silie sup-- pressor near the A end 'lollcing under ti'icse com "'ions would be difi'icull; because por'i; of the me both subscribers mightbe talking witl'i :ueiiiier one hearing iihc other.

in accordance with the present invention it isprrposcdio overcome iilns diliiculty by arranging the colic iressors so that when lg into soon a condiizion that, when two,

subscriber will loc e trouble will be evident an echo euporeseor, ere conneciedi r. lire subscriber at end A begins 1924. semi 1%. 723,796.

such a condition that they maiyiuuciion normally. This control over the echo supderstood from the following detailed, de-

scription when read in connection with the accompanying; drawing, Figure 1. of which iliustiurel'wo iour-wiro repeater circuits uolapted to be connected together in tandem and provided with echo suppressors of the ordinary type, Fig. 2 of which illusirates a similar arrungen'icnt provided with means for rendering, certain of file GClkO suppresssore inefi'eeiivo in accordance with the pros entinveniion, and F19; 3 ()f WlliCil illus trates a tworwire roll circuit which may loo connected to one of the four-wire circuits without affecting lhc echo suppressors.

Referring 130 Fig. 1, .u four-wire circuit is schematically shown, said circuit being equipped with the usual one-way repeaters and :in colic suppressor between stations X and Y, while a similar circuit is shownbeiween stations Y and Z for terminal connections over either circuit. Each individual echo suppressor functionsiu its normal manner, th at is,-wlien transmission takes place "from X to Y the .XY suppressor operates and short circuits" the opposite branch of the four-wire circuit, suppressing echoes from Y, and ice verse.

'X -Y end the Y-Z suppressors waves from the party at'Z'should arrive at the suppressor Z-Y, these waves, would operate the Z Y suppressor, .thus cutting ofi' transmission from X. Furthermore, since the El -Y euppressor would already be operated the transmission from the subscriber at Z could noi get through to X and parties at both X ice ' and Z might be talking for some time with out either hearing the other.

Fig. 2 shows schematically an arrangement for obviating this difi iculty by making both suppressor units associated with one of the four-wire circuits inoperative when the two circuits are connected together in tandem. In this figu're, the operators through toll cord circuit is shown at Y between thetwo four-wide circuits. This toll cord is arranged so that when all four of its plugs are inserted in the. line and network jacks by which the four-wire circuits are terminated at station Y. the line terminals of the four-wire circuits as well as the network terminals will be directly connected together. By means of this connection it will be app-a rent that an almost perfect condition of balance will obtain at each hybrid coil by reason of the fact that the circuit connected to the'lin'ie jack is identical electrically with the circuit connected with the network jack.- In short, there is practically no unbalance at the Y terminals of either tour-wire circuit so that the effect is practically the same as though the individual lines of the two fourwire circuits were directly connected together at station Y.

Further details of the apparatus will be clear from a description of the operation which is as follows: Assume that the lefthand line and net cords at ollicc Y are first connected to the X-Y four-wire circuit, the righthand cords not yet having been connected. Current flt. s from the negative bat tery A, thropgh relay B,, through the normal contact of relay l3, through the simplex connection D derived from the repeating coil L thence through the plug and jack terminals to simplex coil E through neutral relay F, and through polar relay G to ground. Relays B ll, and G are operated as shown so that positive battery C, is applied to the right-hand core simplex D The relay F upon being energized, closes the control wire (which may be a simplex or composite circuit of any well known type if desired) at one point, but the energization of the polar relay G, opens the control Wire at another point so that the circuit of the relay H at the echo suppressor is not closed and consequently the two units of the echo suppressor remain in their normal condition.

The right-hand cords at office Y are then inserted in the Y-Z circuit. Current flows from positive battery G over the contact of relay 13,, through simplex l'). derived from re aeating coil L, over the line plug and jack terminals to simplex E and thence through neutral relay F, and polar relay G to grormd. This current-is of opposite polarity from the current flowing through the left line cord anc operates the neutral relay F, but does not peratc the polar relay G Consequently, ground is connected to the masses Y-Z control wire so that current from battery J in the echo suppressor flows through and operates the relay H thereby opening the short-circuiting connections controlled by the two units of the echo suppressor. The two echo suppressor units associated with the Y-Z circuit are. therefore disabled and the built-up circuit is then complete with only the XY suppressor functioning.

Consequently. when the subscriber at X talks to the subscriber at Z the voicecurrents will be transmitted through station Y over the upper lines of each four-wire cir-f cult. Upon arriving at the point Where the echo suppressor XY is applied, said suppressor will be operated to short-circuit the at this point will be almost perfect as itdoes not depend upon the simulation of areal line by a network. Therefore, the echo currents which will be returned to station Z Y through the hybrid coil at station Y will be '1 so small in yolumetl-et they garded. Any components of the echo curmay be disrerents transmitted from station Z and which pass through the cord clrcuit to the line transnnttmg "from Y to X will have considerable magnitude but will.

not be permitted to pass to station X by reason of the opera- Ition oi the echo suppressor unit XY.

In case the plugs of the cord at oflice .Y had been inserted in thejacks associated with the tour-wire circuit extending from cities Y to office 75 before being inserted in the jacks associated with the four-wire circuit extending between otfice X and oflice Y, a circuit would have been established from negative battery A through the winding of relay B,. o\ the contact of relay 3,, through the simplex circuit D2, Over the ter minals of the plug and jack, through the simplex coil E and through the of relays F and G to ground. "In this case, both relays F and G would be operated without affecting the control wire to the relay H so that the echo suppressor units windings associated with the tour-wire circuit between office Y and office Z would be permitted to function normally. Upon inserting the plugs of the cord into the jacks associated with the four-wire circuit extending from oflice X to otlice Y a circuit would be completed from positive battery 0 over' the .front contact of relav Ba. over the simplex i in tifieial line ei'mneci-ious.

the eireuit previous imme two wire eireun type, "which is not eqi'iippeii wiih echo suppressors and u'liieh extendsfrom oliice if to some other office, as .76 If the through eorii shown in Fig. 2%- is used to connect a toil line of th s r pe with 2; fourwire circuit oi Hie type e'xiemlino; from offi ee X, to oiiiee In the echo. suppressor asso eial'ed wiiih ihe four-Wire circuit will. rei'nuin in operative condition regmfdiesr-i of whether the connection the four-"wire circuit be made before or after Hie connection i'o the two-Wire circuit. in establishing a connec tion from he iwo-wire circuit of Fig. 3 to the fourovire o'ireuii: e'iz'e ulin z; between ofiiee X and oiliee Y of i i 2 only the iine portion of the rorrl eireuit will he usecl, the eonneeiions not being established through the umier hail oi the cord i L'CUi'i', to the orfui'timle networks, such l will he connected to the hybrid eoiis in place of eonneeiions to the-nee WOTli fine es iorlieei'eel by swilxzhes shown. I he iine plug of the cord, circuit be inserted! the line jock of the foui"-wire cireuii before the eorreromiiiiiog; plug" inserted in the line iuoi if the iwo-Wire eir- Quit, the echo 5 3' v and Y X will not he 2i.

" "seer units I--i for the reason that i traced will be established through the relays 13 l and G epei'oting uii three rel vs without producing any-(hung: in the eomroi wire. the other line plug is iTiHi'CiL .er insel'ieel iie ihe jack of the two-wire circuit no control circuit will he (IOIIlPiOiGii us 'ihere no simplex eomie0- the jack of the two tiou ZLSSOLlHiLfi Wlilli wire ciieuii. iii on The other hand, the line ping of ihe eo ii was i erieei in the jack of the two-wire eireuit bi re ihe EOI'IDQ-CiliOH was esi-zihiisheii in the You eireuii, the opal-mien woohi not he any cl Permit, for the. circuit of reiey ii 'u'i'iiilcl not he eompieteci over any smu'ziex LfOUTiLHJL'lQI and house the eircuii' olreuily i raeeii G would he stublis as before.

The tuniim eomrse" -11 between the two fourmzire circuits shown in i i $3 may be extended from office i0 :inomer office at for reieys B ii end the left of biz usiizs' another throu h toll cor-d circuit; at X equipped simili .iy to tiisi; shown. at Y. in this ease the network N Wiii be (iiseoimeeteii irom the hybrid eoii at office X and the hyhrid soil. connected to a network jack :iil o manner similar to that shown at office Y. Assuming that the conneetiou is built up beginning; at office Z, the two echo suppressor units YZ and Z- Y will remain connected to ihe ioonwire eireuit between oiiiee Y and oii'iee Z for the rea- 7Q son that there is no sii'upiei: connection assoeluted with the line jack iii; oi'liCe Z (it being assumed that oifiee 12] is only equipped to make conneeizions to. a terminal lZ'WOjWiZG) line). When the two iouroidre cireuits shown are interconnected byiche cord eir euii; at oiiiee Y the connection will be esteblishecl between the eo rcl'ami the flour-wire circuit between ofiice Y and ofliee Ziirst so that the echo sup iir-essor units "i --25 and E0 IL-Y will stili remain in their opemiive eondiiion. Upon establishing (he connetion to the fouewire eire'uib extending from oiiiee Y to office X the echo suppressor iuiits X-Y and FL-X will be disabled. Upon es- 115 tubiishii ig the conneei'zion at ofiice between these units had already been disabled by the 5 connection estabiisheel st oiliee if so no change in condition takes plate. Upon,

plugging-into the jocks of the fourwvire eir cult amending" to the left of office A the echo suppressor m'voived at the left of is dis 1% ebied in a. manner sirtiiiai? to find) iieseiibed in connection Wiilli the feurmlre'eireuiiz ex tending from ofiiee Y oiiiee Y quently, when the eoinplete oormeeifiioo is es tabiishecl only one poir of echo sup'oii'essoi; units will he opera-hive viz, ilie units. Y -Z and Z---Y associated with the iomwwire eireuit extending from. oiiiee izo oiiiee it will be obvious time the general prioeiples herein iiis'ciosei'l may be embodied in many other organizations wicieiy (iiiierent from those iliustrmbeni Without departiu v from. the spirit of the invenicion as defirie in. the following claims;

What is ele-io'ied is: l

1. In a transmission system e plurality of transmission circuits ziflap eci. to he-eon-. necked in tandem, a. pair of eeho suppressor units associated with, each cirouiii, one unit llCv being; responsive toheurrent-s transmitted in one direction. to disable the circuit for 'i-lfil'lS-z mission in the opposife il'iIEiGiJiOil and the tandem. to render all of the eel f ressor uni-s u eiieotive e iteeloi xiii mi t,$i%ifi$6(i with oiz e fm i T &0

2-. In a transmission system, a plurality of transmission circuits adapted to be connected in tandem, a pair of echo suppressor units associated With each circuit, one unit being responsive to currents transmitted in one direction to disable thecircuit for transmission in the opposite direction and the other unit being responsive to currents transmitted in the opposite direction for disabling the circuit for transmission in said first direction, means for connecting said transmission circuits in tandem, and circuits con trolled by said means for rendering all of the echo suppressor units ineffective except the pair associated with one of said transmission circuits.

3. In a transmission system, a plurality of transmission circuits adapted to be con.- nected in tandem, a pair of echo suppressor units associatedwith each circuit, one unit being responsive to currents transmitted in one direction to disable the circuit for transmission in the opposite direction and the other unit being responsive to currents transmitted in the opposite direction for dis abling the circuit for transmission in said first direction, and a cord circuit for interconnecting a pair of said transmission circuits in tandem, and means associated with said cord circuit for rendering the'pair of echo suppressor units associated with one of said transmission circuits ineffective.

4C. In a transmission system, a plurality of transmission circuits adapted to be connected in tandem, a pair of echo suppressor units associated with each circuit, one unit being responsive to currents transmitted in one direction to disable the circuit for transmission in the opposite direction and the other unit being responsive to currents transmitted in the opposite direction for disabling the ircuit for transmission in said first direcwhereby the pair of echo suppressor uuits-associated with either of the connected transmission circuits may be rendered ineffective while leaving the other pair in operative condition.

5. Ina transmission system, a plurality of transmission circuits adapted to be connected in tandem. a pair of echo suppressor units associated with eaclicircuit, one unit being responsive to currents transmitted in one direction to disable the circuit for transmission in the opposite direction and the other unit being responsive to currents transmitted in the opposite direction for disabling the circuit for transmission in said first direction, a, cord circuit for connecting a pair of said ti nsmission circuits in tandem, and controling circuits associated with said cord ,circuit for rendering the pair of echo suppressor units'associated with either of said transmission circuits inoperative, said controlling circuits being so arranged that When the cord circuit is connected to one of said transmission circuits it will not afi'ect the echo suppressor units associated therewith but when connected to the other transmission circuit the pair of echo suppressor units associated therewith Will be rendered ineffective.

In testimony whereof, Wehave signed our names to this specification this 1st day of July, 1924.

HAROLD S. HAMILTON. SUMNER l3. WRIGHIY

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