US1586972A - Submarine signaling - Google Patents

Description

June 1 1926. v 1,586,972

A. M. CURTIS SUBMARINE SIGNALING 4 Filed August 28, 1924 2 Sheets-Sheet 2 mum/oz:- 4w)? M 6'0/271:

by /W EUEMJLEIHE Application fallen ingest 535$, 1924.. Serial 1%. 34,581.

This invention relates to eubmrine nuling system and more per sicularly to receiving equipment for such lthus for its principal ob ect "the correc- (ion of the cliatortion of signals traneinltte over a long submarine cable and lll'lfill Amplification -0 3 value suitable foi"'"' ;l1e on erutionof u. receiving insurun eii fl W Another object is; to ternnnu a cable which is grounded loln'ough a high 1mpedonce, in such 21 manner as to efficiently ceive Signals. .In the LGCGHlPllSlUni-Ffll? of this object :1. rec wing system 1e groviileil, the impedance of .vhicli viewed iron). too cable in at least several times as lngl'i as the cable impcclence at all frequencies tial lo signaling, and at low frequencies it is many limes as big the oliaructerisuc impatience of the cable. 1 w

Another ohiect is; to "terminate a. lozioeci cable in such ai. manner as to prevent hysteu csis distortion due to the building up to an abnormally high value of low frequency current components. This; is accomplished by providing .a high impedance temnmation for the cable for the low frequency coinponenl's of the signal, which insures that a. long succession of signals. wherein one nolaritv prwloinfinutes, does not cause the currcni all The recei ing i'erniinel of the vuhle to build up lo un abnormally high. value. This is'of great importance in "tho operation of cables loaulecl with nickeliron-or oiher alloy having a. high. permeability at low magnetizing orces, s1ncc the pileup of current oi. one polarity nmkes the cable operate in a. partially magnetized condition and causes: hysteresis: (he iortion of the icceivcd signal.

Another ol j .:i i to icrminzitc a. cable lmluniwl by u lcrui' ml arrangement how in9; 2 high ini 'veslllnIc .v groundconnection so no to ohi'iiin a high rujo o signal strength to out of balance interferzmcc. This is ac- .-om lis;liod by providing a. high impedance lcm'iinnlion for the (:ablc for component frequencies in the neighborhood oi. the Sig"- nuling irerguoncy. This insures; that the ratio of signaling. to out of balance lineriercnce is as favorable possible. The ten minal urru'ngemenl; having a high impedonce ground connec'tlon comprises a partial return circuit terminated at sea including along metallic conduolzor and a network preferably located at the sea termination, the entire return circuit forming a balance for the cable. The advantages of such an arrange re fully explained in a. copending application. of J. .l. Gilbert, Serial No.

new, filecl ring. 28, 1924.

Another object is 'to make possible the eillcient use of a grounded amplifierin com.- hinutiou with a cable balanced by a terminal arrangement having a. high impedancegrouiul'"connection. Such terminal arrangement also prcl.eruhly comprises a. partial return circuit terminated at sea including a long metallic conductor and a network preferehly located adjacent to the sea terminal, the entire return circuit forming a'bulance f0; 'l-ll) cu 1e. The main cable and this terniinul alflq'ilg'lldlll) are inductively as sociuiocd with the grounded en' plifier. This insures the nmlntenence of the balance between the main cable and the terminal arrangement with respechto interference.

in the ei'nboclimenl of this invention chosen for illustration all of'these objects are siznultcneously accomplished. In this embodiment a single core submarine cable loaded with a nickel-iron alloy is terminated in a. twin core saection, each conductor of which is sin'iilarly loaded. At the sea end the t *in core section, one conductor is epliced to the single core cable end the other is grounded through a. substantially .nre resistance having a value upproxionly equal to the characteristic impedance c 9 single core cable. At the shore end,

'tion is terminated in anetof :1 shunted condenser in w-rics null hlllllllfi -(il inductance and a resistance so proportioned. that when couplcd to a. re lug electron discharge arm. plifier by means of a transformer having-a .9 very lllgll ratio of inclnclence to reqistance the nctworl': performs the four functions hcreinbefore (lcfinecl.

The novel features which are l the i .win

considered characteristic of this invention are set forth with particularity in (he appended claims. Theinvenlion, both as to its organization and method of operation to etlier with other objects and advantages thereof, will be furthcr explained hereinntterhaving reference othc accompanying drawing.

Fig. 1 ol the drawingehows diagrammatically the preferred embodimentpf the invention as hereinbetore described.

-Fig; 2 illustrates schematically a type of receiving amplifier suitable for in the system ethic. l... I

Fig. 3 shows modifications of the arrangement. of Fig. 3

Figs. 4, 5 and (3 illustrate the preterred type ol.transl'm'mer construction.

Fig. 7 illustrates a Section of loaded conductor.

Referring now to Fig. '1 of the draw ng a single core submarine cable 5 is terminated in a twin core r-iection ot' submarine cable which extends bet ween the lines l/VlV and X-X. ()ne core 7 of the twin core section 0 is spliced at one end to the single core cable am at the other end is connected to a switch 8 bv means of which it can be connected in upper position to'the signal rcivi v apparatus it and in its lower n) HlLlOl' to the transmitting apparatus 'li. The other core 0 ol the twin core section is connected at-the sea end through a resistance 10 to aeonducti'n' in contact with the .sea water. in the particular arrangement shown, the resistance is connected to the cable armor wires at point 13' and a conventional ground connection shown by dotted linee is used to indicate that the armor WIIPS are ground d. The core f; together with the. network 10 grounded at the point ill constitute a cable balancing return circuit. The

shore end-oi core 9 is connected to the re ceiving apparatus It.

A. type of core suitable for both the single core cable and the twin core section is illustrated ir n. 7. This core' (JUHAIHIFQS a copper cond or Mprovided with a wrap ping 15 of a lllClttil-ll'fi'l alloy as described and claii'ncd in a. copending application oi G. V". llhnenrf lerial No. 557,028, filed May 2, 192 The advantage of using this; loadinn material that its permeability at small magnetizing forces of the order ol 0.0l l 0.10 gauss from 10 to 'times that ol iron, that is, from 2000 to 4000. Over the wrapping of nickel-iron alloy, an insulating layer 10 of Quttapercha or similar material is applied. The cable on which the receiving apparatus herein described is intended to operate, when protected by armor wires in :wcor'danee with the standard snbn'iariue cable practice. has a characteristic impedance which is approximately av resistance of 400 ohms in the range of signaling l'requeir cien.

The reason for employing a cable balancing: return circuit is that interfering (iii-iturbanees local to the shore end of a subnnirine cable are reduced thereby. Such a cart-h arrangement is described and weenie claimed in a copending application of J. J.

Gilbert, Serial No. (548,090, filed June 30,

The transn'iitting equipment T compriscs a well-known positive and negative impulse transmitter 17, series resistance 18 and condenser 19, with shunting resistance 20. As hereinbefore explained, the transmitting equipment 'l may be connected to the core 7 of the twin core section (3 by means of switch 8 in its lower position. Similar transmitting equipment (not shown) is provided at the distant end of the cable 5 fortransmitting t0 the receiving appara us it and need not be furtherdescribed.

'lhe immediate termination for the twin core section 0 consists of a condenser 21 in series with an inductance 22.- Resistance 23 connected in shunt of condenser 21; resist ance 24-, in shunt of inductance 22; and resiatance 25, in series with inductance 22 are provided for the purpose of preventing free oeci1lations,and for the control of the low frequency components of signaling current as will he further described hereinafter. Shielded transformer 26 is used to couple the inductance 22 to a receiving an'iplilier A. The secondary windingfil' of trans former 20 is surrounded by a shield 28 which is connected to the locally grounded terminal of windiin 27.

The amplifier A" may be otany suitable design and preferably employs electron discharge amplifying devices as indicated. The output circuit of amplifier A extends V lilll'(l(i (fll a receiving device which may be a siphon recorder as indicatedi In the arrangement shown theindicating device 20 is located at a considerable distance t'rom the amplifier A and is connected thereto by means of a cable 30. A second indicating device ifl, which may also be a siphon recorder as shown, is connected in series with the output circuit adjacent to the amplifier A. for monitoring purposes.

AS hcreinbetore mentioned,-a cable balancing, return circuit for the cable 5 is provided in order to prevent interference due to local iicldsn The effectiveness of such an arrangement depends upon the conductors I7 and it is therefore obvious that an unbalance to earth of the shore end of the conductors will increase the amount of interference received. It is necessary to veround the lilaments of the amplifier locally at the cable terminal through an cal-thing or stabilizing a and 9 having, equal impedances to earth path of sutliciently low impedance to prevent the amplifier from oscillating, as indicated by the conventional earthing Symbol at the amplifier filaments in Fig. 1. 'lherel'ore, in order to avoid unbalancing the main cable and the cable balancing return circuit with respect to earth it is necessary to couple the amplifier A to theter- Leanne's minating network by means of the transtransmittin a .videran e of i'rciuenc components. Forsignaling-speeds of (it) cycles per second or less, it is desirable that the transformer, when combined with proper shaping networks be able to maintain a nearly constant secondary potential for about a second, if the potentialat the sending end of the cable is held steady through some (T()llll)li1iitl0ll of signals. In order to reproduce the signals accurately it must pass frequencies about 1.5 times the signal ing frequency without distortion. In other words, the transformer must operate elliciently over a range of frequencies from approximately one-tenth to 190 cycles per second. Inorder to obtain the largest possible signal response, when using the cable balancing return circuit, the network termimating the cable and return circuit must have an impedance which is at all 'lrequencies essential to signaling considerably big er than-800 inns, which is approximately the ir'npedan 2 between. the cable and the return circuit. At-high impedance arrange ment for this purpose is d sclosed and claimed in the cop ending" application of .l'.

'5. Gilbert,'Serial No. 734.580, supra. In

order. to prevent the building up of large amplitudes offvery low frequencycurrenr at the receiving end of the cable, and thus to minimize a troublesome form of hysteresis distortion, the network must also have as high an impedance as possible torthe low frequencies. cut invention.

It has been found that by suitably designing the elements of the network and transformer 26}, these requirements can be met. It has also been found that a trans former having' a primary inductance of several thousand henrys and an effective resistance oi the order of one halt ohm per henry at the very low frequencies is suitable.

In order to obtain such a transformer, it is necessary to use for the magnetic core, a

Y nickel-iron alloy which has high permeability at lowmagnetizing forces.

A. suitable type of transformer is illus trated in Figs. 4, 5 and 6. The core is of the shell trans'tormer type and made up of strips of nichehiron alloy, which strips are all of uniform width and thickness, namely 1.7 inches-wide and 6 mils (0.006 ot' an inch) his material as received from the to remove the resulting curl, it is first an-, nealed and then stretched about one-half of one per cent. The core is made up of pieces of two different lengths, namely 7 inches and 8.7 inches. After the stretched mate- This is a feature of the pres kill rial is cut into length it is annealed by slowly cooling from a temperature of IOQO" centigrade. The center liinb of the transformer which carric'sthe windings made up as nearly as ,possible oi metal, while the outer linbs 51 to '5 ii. clu..- e, have onlyonehalf as much material except wherethey overlap each other and the center limb,

thus making the combined area of the cross section of the two outer limbs e'qualto that of the center limb 50. i

The arrangement of the'strips is shown diagrammatically in Fig. 6 which shows the assembled core asvicwed from the lower end of Fig. 5. Their arrangement is also shown in Fig. 4- which is a cross-section of Fig. 5 looking down at a point just above the shield surrounding the secondary Winch 1ng. It is to be .understood that Figs. 4,.

5 and 6 are not drawn to scale.

Although there are four joints in the magnetic circuit. with this type of core -construction'their. effect is largely reduced by the large areas in contact at the corner and at one end of the center limb laminations and by staggering the joints at the short end of the center limb. One'side of the lamina-' nalin current. it is also essential. that the.

windings contain .no short circuitcd turns. For these reasons, thocoils are wound on an arbor in the form-oi pancakes one quarter of an inch thick. The coils in position on the arbor are suitably impregnated, for ex-.

ample, by soaking; in'a wax impregnating compound at- 1?, centigrade 'for several hours. i

The primary Winding-consists of sixteen pancake sections arranged in groups of tours. These are indicated by groupsb l to 57 inclusive. The sections in each group are separated by 0.01 inch-red rope paper and bound together with silk ribbon. The primary sections each contain 1300 turns: of No. 30 single sill: covered copper wire and have a resistance of about ohms. The sections in each group are connected in series and two terminals brought out. ldean's'are provided forconn'ecting the groups in various combinations as desired. y

The secondary winding 58 consists of,

three sections, each of 7200 turns of No.40

single'silk covered copper wire having a resistance of 6700 ohms. The sections are separated from each other by 0.02 inch red rope paper and protected at the ends by 1/32 inch of cardboard. A split shield 59 of one mil (0.001 of an inch) copper is built up around the group of sections and-the whole wrapped closely with silk'i'ibbon. The group "of secondary coils is assembled in the'centerof the core as shown with two groups of primary sections on each side of it. Two terminals are brought out from each secondary pancake and external means are provided for connecting the pancakes in any desired combinations. I

lly far the larger part 01 .the winding, space is occupiedby the primary coil, only suilicient space being occupied by the secondary coil to give a reasonable primary to secondary turns ratio when the smallest wire available is used for the secondary winding. "he use of a high resistance secondary coil is permissible on account of the fact that the secondary coilworks into practically an infinite impedance.

Measurements on the transformer described at a value of current ofthe order of that encountered in submarine signaling show that its primary inductance is (3300' heiirys and its direct current resistance is about 0.28 ohms per hcnry. With the priniary winding closed on. its normal impedance, the leakage inductance measured tram the secondary terminals is of the order of liem'ys. The ratio of primary reactance to primary resistance is not less than 50 from 4 to 20 cycles per second. The capacity between the primary'sections adjacent to the secondary shield and the shield is of the order of 500 micro-micro-farads.

The function of the shaping network will now be considered. The current arriving at the receiving end of a submarine telegraph cable, contains signalin t, current components from nearly zero up to a frequency several times that of the normal signaling t'rt-quency,

but with the lower frequency con'iponenls very much stronger than the higher frequency components and with the high frc-' quency components preceding the low in time of arrival. In order to restore the signal to a recognizable form, it is'necessary to make the conditions for reception as favorable as possible forthe frequency components of the order of 1.5 times the signaling frequency and proportionally less favorable for higherand lower frequency components and at the same time to correct the phase displacements and avoid oscillations in any resonant circuits which may be used. In the present arrangement, it is also necessary to keep the terminal impedance high at all frequencies essential to signaling and particularly high at the lower frequencies in order to minimize hysteresis distortion.

thcsecondary potential to fall.

'ble to do this by taking advantage of the essee-72 l 'hese requirements are met in the network which joins the cable to the amplifier, by the combination of a condenser and an inductance in series, of such values that their reactances are approximately equal at 1.5 times the signaling frequency. Oscillations are avoided by the shunt resistance 24: connected across inductance '22, a proper amount of very low frequency components of the signal are allowed to pass around condenser 21 by way of the high resistance shunt 23, and the ratio of resistance to reactance over the circuit of coil 22 is adjusted to the proper value by resistance The voltage across the inductance coil 22 and its associated resistances 24 and is then impressed on the primary winding of transformer 26 and through it upon the input of the amplifier A. The minimum impedance of the network is then at approximately the resonant frequency of the inductance 22 and'the condenser-'21, and reduces to the effective resistance of these circuits. This arrangement permits the terminal impedance to be raised indefinitely by raising the inductance and correspondingly reducing the capacity. Practical questions of design, however, have so far limited the inductance to about 50 frequency of any signal component im- 'iressed upon it. Since the secondary potential is directly proportional to the rate of change of the primary current, the secondary polential is oi the same form as the primary potential over therange of frequencics for which the primary circuit resistance is low compared to the primary reactance. This may be expressedv in another way by saying that the primary current is the integral of the primary potential, while thesecondary potential is the derivative. of the primary current.

No matter how large the primary reactance is made with respect to the resistance,

it is impossible to maintain a steady potential across the secondary of the transformer,

itthc primary potential is maintained constant. The secondary potential will graduallyi'all to 'zero. It is possible however,

to niaii-itain a constant secondary potential for an 'aj'ipreciable time, if we permit the prin'iy'iry otcntial tocontinne to rise at the corrdct rate to compensate the tendency of It is possifact that the voltage atthe receiving end of a submarine cable continues to rise for several seconds after the voltage is applied to the sendingcud and making adjustments of the receiving network a :cordingly. By this means the system of shaping network and transtori'ncr of Fig. 1, can he 'i'nade to act suhstmtially as if there were no trai'isfornier for as long as one second.

It is obvious that the adjustn'ients ot' the elements of the network between the collie and the amplifier depend not only upon the characteristics of the cubic, hut also upon the speed of signaling and upon the adjustments of any shaping elements which may he included in. the amplifier itself. The shaping elements are therefore made .ljusl:- ahle. Condenser 21 has a capacity of 0.01 to ten micro'faracls, and the shunting resistance 23. a maximum value of two inegi'ihms. lnductancc coil 22 is variable in steps from about one half henry up to henr s. filesistance 24- has a maximum value of 1003000 chins and resistance 25. of 10,000 ohms.

A suitable design for amplifier A. hetween the lines YY and Z-Z oi Fig. 1 is shown in Fl 2. This amplifier comprises (on r stages oi electron discharge amplifiers with suitable coupling circuits and signal shaping networks. The first amplifier 2A is provided with a. negative grid battery of three volts. The filaments oi all of the amplifiers are grounded as shown in Fig. 1 and heated by current from a sir; YOlC hatter-y under the control of rheostats as shown in Fig. 2. i

The output circuit of amplifier 2A is coupled to tl shaping network 101 by means of resistance 102 of 200,000 ohms ani'lcondcnscr 103 of 40 microfaradscapaw it In series with resistance 102 is space current suppl hi'ittcry 2B of 250'volts. The shaping nctu'ork 101 consists ot'pri mary variable condenser 104 ct 0.01 to 0.20 inicrotarads capacity, secondary variahle condenser 10? of 1,000 micro-microlarads maximum capacity, adjustahle resistance 105 of a maximum value of 300.000 ohms, and inductance coil 106 of 10,000 henrys maxi inum inductance and a copper resistance of 45.000 ohms. The design features of a. suitahle coil are set forth in a copending application of A. M Curtis Serial lilo. 600,700., filed l eliruary 10:24 The upper terminal. of coil I00 r-rmnccteiil to the grid of ainplifier 2A? through a negative grid battery 108 of three volts.

.The shaping network 101 is not primarily a resonant network. but comprises an autotranstoriner with an abnormally high ori- 2 mary resistance. T his resistance is so l'lig'h in relation to the primary reactancc at all of the high frequency components of the signal, that the current in the primary cir- Cult is practically in. with the EGltfigh tential acro a merely The 1 across i l lon'erer turns ratio oft the ransforme i so larthat the se- 01d .rir V i. n.) g c '1 a l induced voltage the higher frequency components oi the rial adds'consi'clcrahly to the voltage tr: untied conductively to the secontlar terminals hy the drop in pos the primary resistance. The resulting characteristic of this network 101 that lower frequencies are transmitted to the scone higher): cncies have their voltage increased sunstantinll The phase of the components of the signal are shifted approxi. mately proportionately to their frequency. Under these circumstances the phase shifts do not change the shape of the signal but retard bodily in time hot as the amplification is greater for the higher lire qnencics than for the lower, the attenuw tion of the cable is partly compensated. for. The primary condenser 10% and the second condenser 10! used with caution prii'icipally for the purpose of reducing the effect of interference higher in frequency than any of the essential components of the l and also for ii inducing any desired phase shift 'in the signal.

Amplifier is coupled to shaping network 109 by means of resistance 110 o:t"200,-- 000 ohinsand condenser 111 of 0 micro 'ffllfldS capacity. In series with resistance 110is space current battery 2B" of 2250 Volts. Shaping network 100 comprises inductance coil 112 andfcondenser 110 connected. in series across the sigmaling current output circuit of amplifier 213 The input circuit of amplifier 2ft. including negative polarizing battery 110 of volts. connected across the condenser 113 whicn itself is shunted hy grid leak resistance 115 of two niegohms. Coil 112 has a maximum inductance of 100 henrys and isshimted hy resistance 1142 variable to a maximum of 200,000 ohms. Condenser 113 has a capacity of (1.01 to 0.5: microtaracls.

Amplifier coupled to sha; ing net work h means oft resistance i1 7 of 200; 000 ohms and coinilenser 118 of. 6 micro Liar-ads capacity In series with resistance 11? space current battery 28 of 250 volts .iaping network 120 comprises induct once coil 12.1 and condenser 123 connected in zesacross the signaling current output circuit of amplifier 2A The inputc ircuit of amplifier Zlljincludihg the negative polarir f loath-3 lit-F3 of i0 volts connected across fencer 123 which is itself shunted by cl s'istanoe of two niegohins. {foi A 4 once 100 henrys and is shunted "my resistance 122 l1t t\l21 a. maximum value 9 5301); 000 ohms. Condenser 1233 is adjustable to a n'iazthnum' of 0.2 inicrofaratl. Space current for eniplifier 2A. is supplied hy'hattery 2B of 250 volts. implitier 2A. consists prefer terminals uucl'iauged. While til ably of two vacuum tubes connected in parallel. For simplicity one only is shown.

Commercial vacuum tubes manutacturmh by \Vcstern Electric (.ompany, incorpo rated, are suitable for the amplifiers. Those designated as No 102-1) are preferable for amplifiers 2A, 2A and 2A and those designated as 104-1) for amplifiers 2A.

The networks 109 and 120 are so adjusted as to reduce interfering. currents of fre quencics higher than those essential to signaling. The method of adjusting the shaping networks in the amplifier of Fig. 2 is fully explained in the copending application of A. M. Curtis, Serial No. 690,709. supra.

' A modification of the amplifier of Fig. 2 is shown in Fig. 3. Identical elements in the two figures are indicated by the same reference characters: The modifications are principally for the )urpose of increasing the flexibility of adpistinents and in this way permitting the amplifier to operate well over a larger range of signaling speeds than the amplifier of Fig. 2.

In the amplifier of Fig. 3 coupling resistances 102, 110 and 117 are each adjustable in four steps up to a maximum of 102,000 ohms. The lower values are used for operation at the-lower signaling speeds. to reduce the amount of anuilification. Condenser 103 is adjustable from 10 to 40 inicrotarads capacity. Condensers 111 and 118 each have a capacity of 10 microfarads. Resistance 105 is adjustable up to a maximum of 250,000 ohms. v

The arrangement of the inter-stage networks 109 and 120 have been modified in Fig. 3. A potentiometer 1730 of network 109 has been substituted for resistance 115 and its location changed to a position where it is in shunt of both coil 112 and condenser 113,- instead of in shunt (it condenser 113 alone. Similarly resistance 131 of network l20-has been su'bstitutwl for resistance 124 and has been connected in shunt of both coil l'zland condenser I23 instead ofin shunt of condenser lilil olonc.

while resistance 1:51 has a value of two megohmr/ 7 Networks 109 and 120 may be adjusted so as to consist of a resistance and capacity in series, or an inductance and capacity in all cas once is greatly reduced.

Potentiometer 130 has a maximum resistance of two megohn'is,

wearers by the cable. The seconil-adjustment may be such as to relatively retard the phases of the components up to a certain frequency and advance them beyond that frequcncyfi The third adjustment may be such to act in either manner depending upon the rclaiii tire magnitudesof the three circuitelements.

'l'hcse adjustments with res ect to network 109 will not be effective an ass the potenti. ometer 130 is set at its maximum point.

One method of effecting these adjustments for the purpose of reducing interference} higher in frequency than the signal, is to set till than whenv they are not used, hut'interier- (allies it may be necessary to use these net works for the correction of phase displace merits.

The grid polarizing batteries 100, 102%, 110 and 125'; of Fig. 3 are connected adjacent'to the grounded sides of the filaments instead of adjacent to the grids as in Fig. 2. This arrangement simplifies the insulation.

As hereinlrefore pointed out any specific set of adjustments is dependent upona large number of conditions. As an illustration of about what adjustinentsmight he required for operating at a signaling speed of 56 cycles per second over a loaded cable 2,400

miles long equipped with .a balanced sea.

earth section miles long at the receiving end, the following values for the variable elements are given: Sending condenser 10, 3 microfarails; shunting resistance :20, 11,000 ohms; sending resistance it 20 ohms; sending potential, s8 colts; sent signal. 100% marking.

At the receiving terminal: Condenser 9i, 0.10 nucroiarad; resistance 23, 1,100,000

ohms; inductance 29., 26.5 henrys; resistance of i nductarn-e 22, 253:; ohms: shunting resistance 2 40,000 ohms; resistance 25-. 3.000 ohms: interstage coupling resistances 102. I10 and ll'i' each, 102.000 ohms.

Network nu of Fig. ltlrimary condenser 104,011] microi'aradi primiir indurtauce of transformer 10%;, 200 henrys; primary resistance of transformer lot; and resistance 102'); 200,000 ohms: total inductance of lI'flDSfOll'IlQI 108, 10,000 henrys; secondary condenser 107'. 100 niicro-microfarads.

Network of Fig. 3: Potentiometer i230 (tap at maximum), 2 megohms; inductance 112. 100 henrys: resistance 114, 200,000 ohms: condenser 113, 0.08 microfarad.

Network 1.20mi Fig. 3: Resistance 131 t not adjustable), 2,, megehrns; inductance ohiein of their in long loaded- 121, 100 henrys; resistance 122, 200,000 ohms; condenser 123, 0.02ll'ilClOftlItltl.

From the values given in the above table for the inductance and resistance of element it will be apparent that magnetic material is employed inits magnetic circuit (not Shown). e

The specific arrangements hereinliicfore described are capable of operating at signaling speeds up n ce cycles per second between New York and the Azores over a submarine cable loaded with nickel-iron alloy. A novel terminal arrangement is en'iployed, which adjusted to perform aplu'ralitlv of tune.

higher for the component frequencies below the signaling frequency than for those above the signaling frequency.

2. In a submarine signaling system, a submarine cable, a receivingcircuit comprising an inductive shunt connected between said cable and ground, said. inductive shunt having magnetic material in its magnetic circuit, a signal indicating device connected to receive the voltage drop in at least a part of the inductance of said inductive shunt, and a condenser com'iecte l in series between said cable and said inductive shunt, the relative impedances of said condenser, magneticshunt and indicating device being such that the im 'ieiilance of said receiving apparatus as viewed from said Cillllfl is" substantially higher an. the component frequci'icics below the signaling frequency than for those above the signaling frequency.

3 In a submarine signaling syslen'i, a submarine cable loaded with magnetic material, signal receiving apparatus connected to said cable. and means to make the impedance of said receiving apparatus as viewed from said cable suhstantiallv higher for the comp ment frequencies of the siirnalinr current below the signaling frequency than for those above the signaling frequency.

4. In a submarine signaling system, a

submarine cahle l'oaded With magnetic n a-,

terial; signal receiving apparatusconnected to said cahle and a condenser connectedin series hetwen cable and said receiving the relative nnpedai'ices of said meant/2 a euh as viewed from said cable sul'istantially substantially higher for the component fre quencies below the signaling frequency than tor those above the signalingfrequency.

5'. In a submarine signaling system, a sub 7 marine cable loaded with magnetic material,

a receiving circuit comprising; an inductivev shunt. connected between said cable and.

netic material in its magnetic circuit and a signal indicating device associated with said inductivev shunt, and means to make the 1m- -pedance of said receiving apparatus as ground, said inductive shunt having mageviewed from id cable snostantiall hi her for the component :tzequencies below the sig' naling trerpiency than for those above the signaling frequency.

6. In asuhniarine signaling system, a sub marine cable loaded "with a nickel-iron alloy, a receiving circuit comprising an inductiveshunt havii'ig magnetic material in its ma g1 nctic circuit and a signal indicating device associated with said inductive shunt, and means to make the impedance of said receiv: ing apparatus as viewed from said cable substantially higher for the component frequencies below the signaling frequency than for those above the signalingtrequencv.

7. A submarine signaling system, a subma rine cable loaded with a nickel-iron. alloy having a characteristic impedance of about e00 ohms tor the signaling frequency, a receiving circuit having an impedance for sig nalinc and higher essential frequency components of at least 2000 ohms. 1

8. In a submarine signaling system, a subn'iarine 'cable loaded with a nickel-iron alloy ing: device being; such that the impedance of said receivingap 'iaratus as vieWed from said cable is at least 2000 ohms for all-the component frequencies essential to signaling.

9. In ,a sul'n-narine signaling system, a sub n arimi cable, a receiving circuit comprising,

an "inductiveshunt connected between said cableand ground; said inductive shunt havin magnetic material in its magnetic cirriner, connecting said amplifier to receive 'a'n'electron discharge amplifier, a trans the voltage drop in at least a part of the in} dnctance of said inductive shunt, and. means and return circuit.

to make the impedance of said receiving apparatus as viewed from said cable substantially higher for the component frequencies below the signaling frequency than for those above the signaling frequency.

10. in a submarine signaling system, a submarine cable loaded with magnetic ma.- terial. a receiving circuit comprising an inductive shunt connected between said cable and ground, said inductive shunt having iiiagnct'ic material in its magnetic circuit, an electron discharge amplifier, a transformer coupling said amplifier to said shunt, and means to make the impedance of said receiving'apparatus as viewed from saidcable substantially higher-for thecomponcnt fre: quencies below the signaling frequency than for those above the signaling frequency.

11. In a submarine signaling system, a submarinc'cable loaded with nickel-iro n alloy, a receiving circuitcomprising an inductivc shunt connected between said cable and ground, said inductive shunt having anagnetic material in its magnetic circuit, an electron discharge amplilier, a transformer coupling said amplifier to said shunt, and means to make the impedance-of said receiving appaiatus as viewed from said cable substantially higher for the component frequencies below the signaling frequency than for those above the signaling frequency.

12. In a submarine signaling system, a submarine cable loaded with magnetic material, signal receiving apparatus comprising an electron discharge amplifier and a transformer for coupling said amplifier to said cable, and means to make the impedance ofsaid receiving apparatus'asviewed from said cable substantially higher for the component frequencies below the signaling frequency than for those above the signaling frequency. I

'13. In a submarine signaling system, a submarine cable, a cable balancing return circuit, a receiving circuit comprising an inductive shunt connected between said cable and returncircuit, and a signal indicating device connected to receive'the voltage drop in at least a part of the inductance of said inductive shunt, and means to. make the im 'aedanee of said receiving apparatus as viewed from said cable for all frequencies essential'to signaling materially higher than the characteristic impedance of said cable 14'. In a submarine signaling system. a submarine cable, a cable balancing return circuit, a receiving circuit comprising an inductive shunt connected between said cable and retui'n circuit. and a signal indicating device-associated with said inductive shunt, and means to make the impedance of said receiving apparatus as viewed from said cable for all frequencies essential to signaling materigllyhigher than the characteristic impedance of said cable and return circuit, and.

quency components of, the signaling current.

16. A submarine cable loaded with nickeliron alloy, and a receiving terminal network therefor which comprises resistance, capacity and 1nductance so proportioned that 'n-mn the cable is very high for the low frethe lowest value of the impedance of the net work measured from the cable is several times as high as the charac't'e'risticvimpedance of the cable for frequency components within the essential signaling frequency range.

17. A submarine cable loadedwith nickel-' iron alloyqand a'receiving terminal network therefor which comprises -resistance,'

capacity and inductance so proportioned that the lowest value of the impedance of the network measured from the cable is several times as high as the characteristic impedance of the cable for frequency components with-- in the essential signaling frequency range and materially higher for the low frequency components of that range.

18. A-submarine cable loaded with nickel-- iron alloy, :1 receiving terminal network connected thereto, and a receiving instrument coupled to said network, said terminal network comprising resistance, capacity, inductancc, and a signaling frequency transformer so proportioned that theimpedance of the network measured from the cable is very high for the low frequency components of the'signaling current.

19. A submarine cable loaded with nickeliron alloy, 21 receiving terminal network connected thereto, and a receiving instrument coupled to said network, said terminal network comprising resistance, capacity, inductance, and a signaling frequency transformer so proportioned that the impedance of the network measured from the cable is at its lowest value several. times as high as the impedance of "the cable for frequency components within the essential signaling frequency range.

20. A submarine cable loaded with nickeliron alloy, a receiving terminal network connected thereto, and a receiving instrument coupled tosaid network, said terminal network comprising resistance, capacity,-inductance, and a signaling frequency transformer so proportioned I the network measured from the cable is' atits lowest value several times as high as the impedanceIot the cable for frequency components Within the essential signaling in;-

Leonora quency range, and materially higher for the low frequency components oi that range.

21. A submarine cable loaclco. with nickeliron alloy, a receiving terminal network connected thereto, and a receiving amplifier connected to said network, acid; terminal net work'comprising resistance, capacity, inductance, and a signalin fret uency transformor so proportioned-t lat t e nnpedance of the network measured from the cable 1s, at

its lowest value, several times as high as the impedance of the cable for frequency components within the essential signaling frequency range. i

22. A submarine cable loaded with nickeliron allo a receiving terminal network connected t ereto, and a multistage electron discharge receiving amplifier'having signal correcting networks between stages, said terminal network comprising resistance, capacity, inductance, and a signaling frequency transformerso proportioned that the impedance of the network measured from the cableis at its lowest value several times as high as the impedance of the cable for he i quency components within the essential signaling frequency range. v

23. A submarine-gee le loaded with nickeliron alloy, a cable balancing return circuit,v

and a receiving terminal network therefor which comprises resistance, capacity, and inductance so proportioned that the impedance of the network measured from the cable is very high for the low frequencycomponents of the slgnalingcurrent.

24:. A submarine cable loaded with nickeliron alloy, a cable balancing return circuit, a receiving terminal network connected to said cable and return circuit, and a mult'- stage electron discharge receiving amplifier having shaping networks between stages coupled to saicl terminal network, said ter: minal network comprisingresistance, capacity, inductance, and a signaling frequency transformer so proportioned that the impedance of the network measured from the cable at its lowest value is several timcs as high as the'impedancs of the cable fortrequency components within the essential signaling frequency range;

25. Terminal apparatus for a loaded cable, comprising a transformer and a network for connection between the transformer and the receiving end of the cable, said network being so designed that it tends to augment the effect of the cable in maintaining a steadily increasing electroniotive force across the rimary winding of the transformer as t e result of the maintenance of a steady sending electroniotive torce at the sending end of the cable, the combined effeet of the network and the cable being such that a substantially steady electromotivc "orce appears across the secondary Winding of said transformer for a period of the order of one second. a

' 26. In a signaling system, a submarine cable loaded with'magnetic material, a receiving terminal network therefor comprising resistance, capacity, and inductance so proportioned as to keep the magnitude of the received. current below the value at which substantial hysteresis distortion of, the signals is introduced.

In witness whereof, I hereunto subscribe 192i. a coerce M. o RTIs.

my name this 16th day of August .A. 1).,

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