US1835771A - Submarine signaling cable - Google Patents

Description

. 8, 1931. J. J. GILBERT SUBMARINE SIGNALING CABLE Filed March 23, 1929 'By WM ATTORNEY Patented Dec. 8, 1931 JOHN J. ernaar, or ,pnouenasfrom new LABoaArronInsmoonronarnnorNEWYoan, N. y., Agcnronnmion Vor 4New YORK suBMarNn sienaninecainn .,nppncationfnaMarchas; "1929. seriali-Na erasing".

Thelp-resentinventionlrelates to submarine signaling, and particularly* to the -eiiicient transmissioneoflvoicefrequency currents over long'loaded submarine cables;4

An object V,of the inventionfiis to decrease the attenuation of Vvoice frequency currents transmitted over a long loaded ysi'ibmarine signaling cable. v Y* i Y Another object off'tlleinveht'ion is to'reduce the Yeffects `'of extraneous disturbances upon telephone currents transmitted over long loaded submarine cables. v

Another object of the invention is to reduce the effects of extraneous interference upon the twin core termination of a single core submarine signaling` cable.

A further object of the invention is to -rev duce reflection and modulation losses in the head end sections of a submarine signaling cable and consequently to increase the eliiciency of transmission of the cable as a whole.

F or long distance telephone or high frequency transmission a twin core cable structure possesses important advantages in the way of-freedom from interference. The terminal sections of such a cable are the most 'critical portions both from the standpoint of losses due to the unsually great current lat the transmitting end but also due to the fact that interference is likely to be most troublesome near the terminals. For practical reasons, a long deep sea signaling cable is usually manufactured in a number of sections of about one mile length which laying operation. Owing to inherent manu-y facturing conditions the electrical properties of the individual sections will not be identical in all sections. There are .particularly three electrical characteristics of primaryimportance, herein referred to as the parameters, which will be found to differ, namely, first, the initial inductance (i. e. the inductance at Zero current density) second, the capacity; and third, the variation of hysteresis resistance with current. s

The present invention ,makes use ofthese facts and applies them in the following manner: During manufacture, the parameters of the cores are measured and from lthe results of these measurements the cores are selected are joined during the into `groups Lso Lthat ithe y'cores in v:any `group have `as Vnearly as 'possible identical initial inductance )Of the members of any Vgroup Yonnfassrenon no yanni. `,griirfiiirrour. 1.1

there arethen selected pairshavingasnearly o as possible the same capacity. The -conductors ar-e thenf twistedA or-laid together `spir'ally 'intopalirs andthe-'pairs arranged 'in order-fof decreasing hysteresis resistance. During? the Y laying ofthe ,cabler the pairhavingthe lowest i hysteresis'resistanee is placedvnear the cable terminal and l'those pairs having successively higher hysteresis resistance are placed in successive positions more )remote 'from the A1terminal. I'For a two-way cable the Y other jterminal will :be treated inithe same fashion. Ina cable in accordancewiththe present invention the separately Ymeasured l'impedanc'es of fthe 'twinned cores *measured from anyf'two points on-fthe cable and looking t the same direction will 'f be as A`nearly equal'` as This has the advantage-@that eX possible. traneous interfering electric and magnetic fields, 'such as thoseemanating from :nei-ghboring electriccables,fromthe effects ofthe earths-:magneticeld and lfrom static disturbances Awillloe'balanced outA with respect 'to A'the twin core cable. Y Also in the terminal sections of'the cablewheretheflargest currents are encountered, the increase of4 attenuation due-:to hysteresis willbe minimized. v

'The ,eect of extraneousfinterferenceisreduced by matching-the cores yas regards the inductance andvcapacityg and at the same time sthe increased attenuation due to 1 hysteresisalosszisniinimized.' l The hysteresis resist# ance, upon which'the increasedlattenuation depends, is,

one,ccnductor to-another. An limportant featu-reofthe invention, therefore,is to use inthe ihead end-sections of the cable, `wlfiere the lcurrent' islarge,vcores .whichhave a-smail-l value forithisconstant lof proportionality; lrnthe.- .case :ofra ztwinvcore :termination .offa single core cable the niethod of selecting in aV shortllengthiof conductor, Vproportional tothe current inthe; conductor. The constant of :proportionality var-ies from cores may :abe somewhat :different from :that

employed in the manufacture fof' a r twin ecore" cable.` Theicalole coresjimayiiirstloegrouped' as vregards @hysteresis resistance, vthose having low hysteresis resistance being selected for the terminal sections. These cores may then be paired so as to obtain the desired balance to.: Suitable heat treating of inductance and capacity. It is however, possible to use this same method of selection also in the manufacture of a twin core cable. In, the "accompanying drawings which show one embodiment of the invention `:A e,

The central copper conductors 10 are surrounded by a numberof segments 11,say six, shaped" /towlit the:v central conductors "110. Upon the segments 11 is applied a helix of loading material 12. Suitable loading materials and suitable methods of applying loadmg materials are known and need not be dis'- cussed herein. v 'I heconductor, is heat treated after the' loading material applied theremethods such as are .well known may be employed. The loading material is surrounded by a pressure equalizing fluid, such as liquid bitumen or melted rubber;-

Surrounding Vthe loading Y material is a sheathof insulating material 13 selecting k,from a group thus A tute.

`scribed constitutes a unit hereinafter re` such as gutta percha or guttapercha substi- The entlre structure` thus far de# ferred to as aY-core. Two such cores are twinned together in a twinning-machine and given a spiral lay or pitch as indicated in Fig. 2. The pitch is preferably of the order of several feet. In order to give this twinned core the cylindrical shape requiredfor armoring, the interiorly cusped crescent shaped spaces on both sides thereof are iilled by a suitable filler 14, suchas jute, which is moldled around the twinned cores to produce a spherical cross-section. Teredo tape 15, jute 16,andarmorrwires 17 are provided to surround the cores in asuitable manner. Y

l The invention has .been described specifically as applied to a continuously loaded subrine cable which comprisesselecting from a number Voi" core lengths agroup having, Vas nearly aspcssible, equalityfof inductances, rformed @pairs having, as nearly as possible, equality of cae pacity, to'form. a twin core section, and arranging the twin core sections ythus formed in order of increasing'hysteresis(resistance losses as one proceeds-from the terminal toward the center of the cable. e.

vand lplacing those each to the other, las to one parameter and the twin cores are arranged progressively in the cable in accordance with a different parameter.

3. A submarine cable of the twin core type in which the twin core lengths of a section are matched each to the other as to their inductance characteristics and the twin core lengths are arranged progressively in the cable in accordancewith increasing hysteresis resistance as one proceeds fromv a terminal toward the center of the cable;

"4.' Inl constructing a submarine signaling cable of great overall attenuation from sections of loaded cores the impedance of which varies, the method of reducing irregularities inthe completed cable, which method comprises arranging the sections in pairs balanced with respect to their impedance values, pairs havingl the highest hysteresis resistance toward the mid-portion of the cable v v A In witness whereof, I hereunto subscribe my name this 15th day of March, 1929.

- JOHN A J. GILBERT.

i "2. VA submarinecable of twin'coreitype l which thetwin core lengthsare matched,

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