US1751333A - Interquad capacity balancing of telephone cable circuits - Google Patents

Interquad capacity balancing of telephone cable circuits Download PDF

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Publication number
US1751333A
US1751333A US323674A US32367428A US1751333A US 1751333 A US1751333 A US 1751333A US 323674 A US323674 A US 323674A US 32367428 A US32367428 A US 32367428A US 1751333 A US1751333 A US 1751333A
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values
equation
variables
capacities
balancing
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US323674A
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Jordan Hans
Goldschmidt Robert
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General Electric Co
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General Electric Co
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/32—Reducing cross-talk, e.g. by compensating
    • H04B3/34—Reducing cross-talk, e.g. by compensating by systematic interconnection of lengths of cable during laying; by addition of balancing components to cable during laying

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  • This invention pertains to capacity balancing between closely paralleling transmission circuits with the object of preventing current impulses transmitted over one such circuit from influencing the other circuit through the medium of capacitative couplings between such circuits. More specifically, the invention discloses a novel scheme applicable principally to quadded between the transmission circuits of a first and of a second quad in such 'manner that signals transmitted over the circuits of the one quad will produce no interfering effects upon the circuits of the second quad or vice versa.
  • the invention in essence consists in measuring the capacitative couplings between the speaking circuits of 'the irst and coupling values thus obtained, determining directly by means of a mathematical process the values of nine fixed capacitieswhich, when properly connected between suitable conductors of the one and of the other quad in accordance with the coupling equations will cause all the inter-quad couplings between the transmission circuits simultaneously to disappear so that the speaking circuits 3 of the one quad will produce no interfering ei'ects upon the speaking circuits of the other telephone cable for balancing the couplings those of the second quad and, from the has formerly been necessary in balancing up Inter-quad capacities to measure and correct the couphngs between certain speaking circuits before the coupling 4between other speaking circuits can'be measured and cor- 5l) rected.
  • a third advantage ofthe scheme dis- -closed herein consists in the fact that, in
  • the capacitative unbalances of short sections of cable ' can be offset by suitably connecting iXed capacities between certain conductors of the one and the other groups of speaking 'complete symmetry between quads, by makmg sixteen part capacities all equal or (2) by .balancing up the nine capacitative couplings between speaking circuits.
  • the present invention starts from the conce tion of removing the nine capacitative couplmgs bythe method of Vconnecting only nine condensers between the conductors of the'speaking'circuits.
  • no method has been outlined for determining the values and mode of connection of 'i these nine balancing condensers in a practical case.
  • a novel mathematical procedure has,
  • Figure 1 shows schematically a pair of quads in a cable with the sixteen part capacities between the conductors of the one and of the other quad indicated.
  • Fig. 2 shows a diagram of two speaking circuits with the part capacities between the conductors of the one and the other indicated.
  • Fig. 3 shows the quads of-Fig. 1 with the part capacities()1 to C16 not shown, and with certain balancing capacities indicated.
  • Fig. 4 shows a chart used in mathematical determination of thel balancing capacities.
  • Fig. 5 gives a chart in which a numerical example illustrating the determination of the balanced up, using the last met balancing capacities in .a worked out.
  • Fig. 1conductors l1, 2, 3 and 4 constitute one quad of the cable while conductors 5, 6, 7 and 8 constitute apsecond quadltherein.
  • the side circuits are indicated byA1 and A2, respectively, while the phantom is indicated by A.
  • the corresponding designations are B1,
  • the capacities C1 t0 C16, inclusive, show all possible part capacities between the tors of thesecond quad.
  • the arrangement constitutes a balanced bridge of which the capacities r1/1 t0 n1, inclusive, are the balancing arms and conductors AB the equipotential points.
  • Equation (2) if the ratio on the left side of the equation does not equal that on the right, it can be ina-de the same by connecting in shunt with one of the capacities fn, a single capacity :t of proper value to reduce the equation to an equality.
  • FIG. 3 shows sections of. the uads A and B of Fig. 1, with the capacities 1 to C16 not indicated, each side circuit to side circuit cou ling can be libd discussed above, by connectmg onl'y a single condenser ⁇ between a conductor of one and v quired in or same manner, f in to phantom couplings, each circle A to D repthe other side circuit.
  • Fig. 3 shows the balancing ofthe coupling between side circuits A1 and B1 by means of the single capacity t1.
  • the other side'to side couplings AIBZ, A2B1 and AzBz . can correspondingly be balanced up by suitably 'connecting a single condenser in each case.
  • each capacity n is the sum of the four-part capacities between such pairs of conductors.
  • condensers ti to t7 indicate the mode of connecting the balancing capacities for this case.
  • the method outlined immediately above desciibesthe ⁇ known procedure for balancing up the inter-quad capacitative couplings. It will be seen that the method requires a total of sixteen capacities. The method is cumbersome inrfthat the side to side couplings must be measuredand corrected before measurements can be made Aon the side to phantom couplings, since the balancing up of the former effects the latter. Similarly, the side to phantom couplings must be measured and corrected before the .phantom to phantom coupling can be attacked.
  • Equation (6) vcan be applied to the nine couplings between the speaking circuits of quads A and B of Fig.l l, reinem'- bering, of course, that wherever a phantom circuit is involved, two or four part capacities must replace certain of the single capacities of Equation (6).
  • the values w1 to m16, inclusive are the additions to part capacities C1 to C16, respectively, of Fig. 1 required for removing the couplings.'
  • Equation' (a) by apportioning the measured value of the coupling constant equally among the variables of opposite sign thereto, the remaining variables, for the moment, being assumed zero.
  • the measured value k1 is positive
  • the sfolution of Equation (a) is assumed in the orm with w1 to :1:4 and w13 to m18 taken as zero.
  • the values of the variables assumed for the solution of Equation (a) are substituted in Equations (o) to (i) inclusive, respectively, it will be noted that in each case they produce zero resultant effect on such equations, owing to the sequence of the signs 'of the variables in such equations. For example, if
  • Equation (b) the value -gl be substituted in Equation (b) for the variables m5 to m15, the effect will be zero, since m5 and we are negative, while and wg are positlve.
  • Equation (b) since theyare not present therein.
  • Equation (a) the assumed solution of Equation (a) to any of the Equations (b) to (i), inclusive.
  • the assumed solution, while valid for Equation (a) has ⁇ zero resultant eiect upon Equations (b) to (i) inclusive.
  • the same result would follow had the measured value of cl been negaive, requiring the assignment of the value .8 I toa/116, inclusive, of Equation (a) in order to establish an equality.
  • Equation (b) vfor the moment, assumed equal'to zero.
  • Equation (b) it will be noted from an inspection of the signs of Fig. 4, has zero resultant eect upon the remaining Equations (a) and (o) to (i), inclusive.
  • Equation (a) inserting the value for the variables ma to ma in Equation (a), it will be seen that the total eect is Zero, since ma and ,mi are positive while m5 and 006 are negative in such equation. A similar result will likewise be obtained for Equations (c) to inclusive. Also, if the measured value of k2 were negative instead of positive the same result would follow by assigning the value yg to the vari-v ables w1, m2, m7, and w8.
  • Equation (c) yis assumed by'assigning the value 1%* to the variables of opposite sign thereto in such equation, and likewise, in Equation (d) -a-solution is obtained by assigning the value Iii to the variables of opposite sign thereto, and in Equation (e) as# signing the value to the variables of op-
  • Equation (f) if a value l@ is assigned to the variables of opposite sign, an inspection of Fig.
  • Equation (a) 4 will show that the solution thus assumed, while producing zero resultant effect upon Equations (b) to (e) and (g) to (i), inclusive, will produce a coupling elitect when the values are substi-4 tuted in Equation (a).
  • the measured value la@ is negative
  • the value @2g is assigned to the variables m1 and m4 in Equation (f)
  • Substituting these values in Equation (a) gives a total resultant eeet equal to Ica, since both m1 and'. aai are. positive in Equation (a).
  • Equation (a) In order, therefore, to oilset the effect of the assumed solution for ae, inclusive.
  • Equation (f) on Equation (a) in addition to assigning the value 4 is also assigned toA the variables m5 to w8, inclusive, or to the variables m9 to w12.
  • the value t2? is assigned to the variables :v1 and w, and
  • the value 4 is assigned to m5 to w' or m9 to w12, inclusive.
  • Equation (a) certain squares lin Equation (a) would contain ⁇ the value 1 and in Equation (b) certain 'squares would contain thev value i, etc.
  • Table II (a Values 1 to 4 in Groups I to IV 1 Values 1 to 4 in Groups I and II 62 Values 1 to 4 in Groups I and III b3 Values 1 to 4 in Groups? III and IV fb., Values 1 to 4 in Groups II and IV (c1).
  • Values 1 and 2 in Groups I and II (c2) Values 3 and 4 in Groups I and II (c3) Values 1 and 2 in Groups III and lIV .
  • Values 3 and 4 in Groups III and IV (c5) Values 1 and 3 in Groups I and III (ou) Values 2 and 4 in Groups I and III (c7), Values 1 and 3 in Groups II and IV (08) Values 2 and 4 in Groups II and IV simultaneously by the same amount.
  • Equa# tion (g) the solution is 2 assigned to the lc i' to a', to an, inclusive, 1n Group I.
  • Equai tion (70,7% isffifsisigned to the variables of assigned to the variables of opposite sign is assigned to the variables opposite sign in Group III and to the u valuables/a1 to m4, mclusive, 1n Group I.
  • column 1 of the chart shows the coupling designations in accordance with Fig. 1.
  • Column 2' gives the coupling designations, as icl, 102, etc.
  • Column ⁇ 3 gives the. -measured coupling valuesy 1n an actual case,
  • the measured coupling constant k1 was +100, k2 +80, etc.
  • the upper portion of the squares in column 3 are marked negative and thel lower portion positive, andthe measured coupling value is in each case Written in opposite its proper sign.
  • the shaded portions under the variables w1 to m16 block out the s of the samesign as the measured coupling value, since the coupling value is never apportioned among such variables. For example, referring to the coupling A/B.
  • the measured coupling is +100, and since the variables m1 to are positive the lower portions of the squares are blocked out, preventing the apportionment of the coupllng among such variables, While the lower l portion of the squares corresponding to m5 to m8, inclusive, are leftfree, permitting the apportionment of the coupling constant among them since the signs of these variables are negative.
  • the measured coupling value is apportioned equally among the variables of opposite sign in accordance with'the rules outlined above, and to prevent a coupling effect on Equation (a) an additional apportionment of E is assigned to' all the variables of Group I or Group II, asv the case may be, to
  • the final step in the solution consists in altering the general solution of line T in such manner as to'reduce four additional roots to zero.
  • the first balancing point consists in limiting the coupling apportionments to Groups I and II,-then at the second point, the coupling apportionments should 'be limited to' groups say II and IV, and at the next point,- to Groups I and III, and so 0in-using all the combinations over and over again in regular succession.
  • Method for balancing the couplings between adj acont-quads, especially in telephone cables which consists in measuring the interquad couplings between the transmission circuits of the one and of the other quad, calculating from such measured couplings directly the values of the nine capacities for balancing the same, suitably connecting between the conductorsof the one and of the other quad, nine such capacities .whereby the inter-quad couplings are simultaneously made to disf' appear.
  • Method for balancing the couplings between ad'acent quads, especially in telephone cables, vvv ich consists in measuring the interquad couplings between the transmission circuits of the one and of the other quad, apportioning the measured couplings values vequal- Ily among the balancing capacities of opposite sign thereto in their respective coupling equations, rendering such apportionments in the side circuit equations ineiective asapplied to the phantom equation by further apportioning the couplings in the respective side circuit equations equally among four successive capacities of proper sign not occurring therein, summing up the values thus assigned the respective balancingl capacities, successively altering through c anges ineffective as to the individual equations thel set of resultant sums through like changes simul# taneously applied to certain groups thereof, until finally seven of the sixteen possible sums are'reduced to zero while the remaining nine assume positive values, pro erly 'connecting between ⁇ 'the conductors o the one and
  • equations limiting such apportionment in a vance except for the equations having no f capacities therein, to two groups of four successive capacities, each -said group having i opposite dering s equations ineffective as applied to the phansi s in the phantom equation, rend apportionments in the other tom equation by further apportioning the y couplings in such other equations equally among the capacities in one group aforesaid of proper sign, summing up the values thus assigned the respective balancing capacities, successively altering'through changes ineffective as to the individual equations the set other quad, ninecapacities corresponding to said n1ne positive values whereby'- all the intersquad couplings aforesaid are simulta' neously made to disappear.
  • Method for balancing the couplings be tween adjacent quads, especially in telephone cable, which consists in-measuring the interyquad couplings between the transmission circuits of the one and of the otherquad, apportioning the measured couplings equally among the balancing capacities of opposite sign thereto in their respective coupling equations, limiting suchv apportionment inl advance except for the equations having no capacities therein, to two groups of f'our successivev capacities each, havin opposlte signs in the phantom equation, ren ering such apportionments in the other equations ineffective as applied to the phantom equation by further apportioning ⁇ the couplings in such other equation equally among the capacities in one group aforesaid of proper sign, summing up the values thusl assigned the respective balancing capacities, successively alter-l ing through changes ineffective as to the individual equations the set of resultant sums through like changes simultaneously applied to certain groups thereof, until at first iive sum

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US323674A 1927-12-22 1928-12-04 Interquad capacity balancing of telephone cable circuits Expired - Lifetime US1751333A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2794074A (en) * 1952-08-08 1957-05-28 Nederlanden Staat Reduction of far-end crosstalk in a telephone cable at carrier frequencies
US5966056A (en) * 1996-01-26 1999-10-12 Int Labs, Inc. Method and apparatus for enabling the transmission of multiple wide bandwidth electrical signals

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2794074A (en) * 1952-08-08 1957-05-28 Nederlanden Staat Reduction of far-end crosstalk in a telephone cable at carrier frequencies
US5966056A (en) * 1996-01-26 1999-10-12 Int Labs, Inc. Method and apparatus for enabling the transmission of multiple wide bandwidth electrical signals

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