United States Patent (19.
`Jachimowicz et al.
`
`(11)
`(45)
`
`3,894,172
`July 8, 1975
`
`MULTICABLE TELEPHONE CABLE IN A
`COMMON SHEATH
`Inventors: Ludwik Jachimowicz, Elizabeth;
`Jerzy Adam Olszewski, Edison, both
`of N.J.
`Assignee: General Cable Corporation,
`Greenwich, Conn.
`Nov. 6, 1973
`Filed:
`Appl. No.: 413,206
`
`U.S. Cl..................... 174/34; 174/27; 174/103;
`174/107; 174/110 F
`Int. Cl. ........................................... H01b 11/00
`Field of Search......... 174/33, 34, 27, 103, 107,
`174/113 R, 105 R, 105 B, 23 R, 1 16, 110 F
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`References Cited
`UNITED STATES PATENTS
`3/1962 Cook.............................. 174/34. UX
`7/1963 Martin.................................. 174/34
`
`3,025,656
`3,099,703
`
`
`
`8/1963 Cook et al........................ 174/34 X
`3,102,160
`3,109,879 1 1/1963 Martin.................................. 174/34
`3,271,508
`9/1966 Burr.................................. 174/34 X
`3,344,228
`9/1967 Woodland et al.................. 174/107
`3,622,683
`1 1/1971
`Roberts et al.................... 174/27 X
`R27,206 10/1971
`Gabriel et al................... 174/103 X
`FOREIGN PATENTS OR APPLICATIONS
`923,900
`4/1963 United Kingdom................... 174/34
`Primary Examiner-Arthur T. Grimley
`
`ABSTRACT
`57
`This communication cable for telephone use has com
`paratively small numbers of pairs with the conductors
`of each pair twisted together with different lays and
`the pairs are assembled into shielded units. These
`units, which are preferably of the same construction as
`one another, are assembled in a twisted cable core
`with a shield around the core and spaced from the
`units, and a plastic jacket, of conventional construc
`tion, covering the shield.
`10 Claims, 4 Drawing Figures
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`2
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`PATFHTERJUL
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`8
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`1975
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`3.894.172
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`Page 2
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`“A
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`CommScope Exhibit 1014
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`3,894,172
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`O
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`15
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`2
`1.
`with an overlap or, if more efficient shielding is desired,
`MULTICABLE TELEPHONE CABLE IN A
`the helical tape over the longitudinal shield may be me
`COMMON SEATH
`tallic of the same metal as the longitudinal component.
`BACKGROUND AND SUMMARY OF THE
`Several identical shielded units are then cabled to
`INVENTION
`gether.
`Other objects, features and advantages of the inven
`There is an increased use of telephone cables having
`tion will appear or be pointed out as the description
`symmetrical (balanced) pairs as a transmission medium
`proceeds.
`for sending pulse code modulated (PCM) signals. A
`difficulty developed when the rate of pulses was in
`BRIEF DESCRIPTION OF DRAWING
`creased. At about 1.5 Mbit/sec. (megabitz per second)
`In the drawing, forming a part hereof, in which like
`the crosstalk between pairs was tolerable but when the
`reference characters indicate corresponding parts in all
`rate was increased to the level of 3.5 or 5 Mbit/sec. the
`interferences, which are roughly proportional to fre
`the views:
`FIG. 1 is a diagrammatic cross-sectional view of one
`quency, made conventional cable unsuitable for trans
`mission in both directions on pairs confined in one
`of the units of which the cable of this invention is made:
`FIG. 2 is a diagrammatic view showing two pairs of
`common cable sheath.
`The remedy was to place instead of one, two separate
`conductors illustrating the difference in the twist (lay)
`of the pairs;
`cables, one for each direction of transmission to avoid
`differences in levels (magnitude of voltages) between
`FIG. 3 is a diagrammatic view of the cable of this in
`signals on go and return circuits. Apart of being more
`vention showing the way in which the units are assem
`20
`expensive and requiring two conduits, one for each ca
`bled, shielded and provided with an outside plastic
`jacket; and
`ble, the remedy still had its limitation when repeaters
`spacing was increased, to take advantage of the ab
`FIG. 4 is a side view of the cable of FIG. 3 with parts
`broken away to illustrate the construction when viewed
`sence of near end crosstalk limitation. Far end cross
`talk, cumulative with cable length, became the limiting
`from the side of the cable.
`factor, since the sum of unwanted energy, arriving into
`DESCRIPTION OF PREFERRED EMBODIMENT
`a given pair via far end crosstalk from large number of
`pairs in a cable, became prohibitive for a reasonable
`FIG. 1 shows a pair of insulated conductors 10, an
`signal to noise ratio. (S/N ratio).
`other pair of insulated conductors 12 are located in the
`same region as the pair 10 but somewhat lower. down.
`In order to minimize crosstalk, it is necessary to avoid
`proximity of pairs of the same, or nearly the same, twist
`A third pair of insulated conductors 14 is shown at an
`(lays). The length of pair twist which can be employed
`intermediate level. These three pairs 10 - 14 are each
`twisted with a different lay, as will be explained in con
`is limited, however, from the smallest (approximately
`1% inches) to the largest (approximately 5 inches).
`nection with FIG. 2.
`35
`Longer lays are impractical because in the process of
`The pairs 10, 12 and 14 are located centrally in a
`assembling pairs in the cable it is not possible to retain
`cable unit 16; and there are other pairs of conductors,
`accuracy of the twist. In large cables, having 50 pairs,
`each indicated by the reference chracter 18 located in
`there is a need to employ at least 22 pair lays to avoid
`a circle around the three pairs 10 - 14. Each of the
`proximity of pairs of the same twist length.
`pairs 18 is twisted and all of the pairs in the unit 16
`40
`Dividing the available 5 inches -1.5 inches = 3.5
`have a different lay to their twist.
`inches into 22 steps, makes one step only 3.5 - 22 F
`The pairs 10, 12, 14 and 18 are assembled in a bundle
`which preferably has some twist; the three pairs 10, 12
`0.15 inches long, not sufficient step to obtain desirable
`and 14 being in the center and the 9 pairs 18 forming
`crosstalk separation between pairs. If, however, the
`an outside layer for a 12 pair bundle. The unit 16 can
`same available 3.5 inches are distributed between lays
`of 12 pairs the separation steps available are doubled
`be made with more or less pairs in the bundle.
`and/or the designers may drop from consideration the
`To lock the pairs 10, 11, 14 and 18 together and pre
`longest lays, say over 4% inches, thus improving pro
`vent lay distortion when the bundle is handled in manu
`facturing processes or at installation, a thin jacked of
`cess reliability in assembling 12 pair bundle. All these
`measures permit wider spacing between expensive re
`foamed polyethylene 20 is extruded over the bundle.
`The pairs can be held together in the bundle in other
`peaters, since cumulative crosstalk powers are made
`ways, if desired, as by applying a tape made of foamed
`smaller by decreasing number of pairs in cable, and im
`thermoplastic supported by a film such as Mylar or
`proving crosstalk between the pairs by better selection
`polypropylene, or other material.
`of pair twists.
`A metal shield 24 is placed over the jacket of foamed
`The cable of this invention consists of a multitude of
`55
`material 20. One of the advantages of the jacket or tape
`identical small cables twisted together to form one
`of foamed material 20, in addition to holding the pairs
`cable core. Over the cable core there is one common
`cable sheath of a conventional design. Each of the elec
`assembled in the bundle, is that the foamed material
`separates the pairs from proximity to the metal shield
`trically separate small cables consist of a bundle of 12
`transmission pairs with possibly one pair added for con
`24 which is applied over the foam.
`60
`The shield 24 is preferably a longitudinally applied
`trol and supervisory circuit. The pairs of the bundle
`(unit) have each a pair lay (length of pair twist) differ
`folded aluminum or copper tape held around the unit
`16 by a plastic insulating tape 26 applied helically with
`ence from lays of remaining pairs in the unit. The bun
`an overlap or the helical tape may be applied over the
`dle can be assembled with three pairs in the center and
`longitudinal shield and may be of the same metal as the
`nine in the outside layer.
`65
`longitudinal shield, as previously explained.
`A shield over each assembled unit may consist of a
`longitudinally applied folded aluminum or copper tape
`FIG. 2 shows the pair 10 with a helical lay of 1%
`held around the unit by a plastic tape applied helically
`inches as indicated by the dimension arrow. FIG. 2 also
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`3,894,172
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`3
`shows the pair 12 with a lay of 2 inches, also indicated
`by a dimension arrow. In FIG. 2 the insulated conduc
`tors of the pairs 10 and 12 are shown loosely twisted for
`better illustration. Each pair within the unit 16 has a
`different lay to its twist so that crosstalk separation is
`obtained between the pairs. One of the advantages of
`using a unit 16 which contains a relatively small num
`ber of pairs is that the difference in lay between the dif
`ferent pairs can be larger, within the permissible range
`of 5 inches to 1.5 inches, than is the case where there
`are more pairs in the same bundle of pairs.
`FIG. 3 shows a communication cable with approxi
`mately 144 pairs. This communication cable, desig
`nated by the reference character 30 is made up of 12
`units 16 and in FIG. 2 these units are indicated by the
`reference character 16 with a different letter a through
`p appended.
`The cable 30 is made up of 12 units with three central
`units 16a, 16b and 16c and with the other units ar
`ranged in a circle around the central units as clearly
`20
`shown in FIG. 3. The units 16 are cabled and then
`wrapped with a standard core wrap, such as Mylar 32.
`A moisture impervious shield 34 is placed over the core
`wrap 32.
`This shield 34 may be a strip of aluminum foil with
`a polyolefin coating on both sides to protect it from
`corrosion. Adhesive polyethylene is commonly used for
`such shields and the strip from which the shield 34 is
`made can be folded longitudinally around the core of
`the cable 30 with the edge portions at the seam bonded
`together in accordance with the conventional practice.
`This shield 34 is preferably circumferentially corru
`gated as shown in FIG. 4.
`A protective jacket 38 is extruded over the shield 34
`to provide a smooth outside surface; and this jacket 38
`is preferably made of high density polyethylene or
`other plastic which is tough enough to protect the
`shield 34 from mechanical injury during handling and
`under the conditions in which the cable 30 is to be
`40
`used.
`FIG. 4 shows the units 6d, 16e, 16f, 16g and part of
`the unit 16f as they are cabled with a long lay. The
`outer shield 24 and the foam 20 are broken away for
`a portion of the exposed length of the unit 16.f so as to
`show the pairs 18 within the unit 16f All of the units
`16 are preferably of the same construction, as previ
`ously explained, but because of the shielding around
`each unit the pairs in one unit do not disturb the pairs
`in the next unit.
`The pairs 10, 12, 14 and 18 are locked in reference
`to each other by means of the foamed jacket 20 or
`foamed tape, previously described. The interstices be
`tween the pairs in the unit 16 are preferably left with
`only air within them. It is unnecessary to use filling
`55
`compound in the units 16 because these units are pro
`tected from contact with moisture in the cable 30.
`If the cable 30 is to be used under conditions where
`damage to the shield 32 is likely to occur, then the
`cable 30 is filled between the units 16 with cable filling
`compound. This prevents water which gets into the
`cable 30 through a break in the cable shield from run
`ning down hill and accumulating hydrostatic pressure
`to force itself under the overlap of the Mylar which is
`helically applied to the group of unit 16 under the me
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`tallic shield 34.
`Since the units 16 themselves are not filled, the cable
`of this invention has the advantages of a filled cable in
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`4
`the event of a break in the shield 34, but still has air
`around the pairs in the separate units 16 with resulting
`lower capacitance and smaller dimension of the cable.
`The preferred embodiment of the invention has been
`illustrated and described, but it will be understood that
`the cables of this invention can be made with more or
`fewer pairs in the individual units 16 and that the cable
`30 can be made with more or fewer units. Any of the
`units can be used for one or another direction of tra S.
`mission and the number of units, individually shielded,
`is limited only by the consideration of outside diameter
`of the cable 30 to fit available duct space.
`Changes and modifications can be made in the con
`struction illustrated and some features can be used in
`different combinations without departing from the in
`vention as defined in the claims.
`What is claimed is:
`1. A communication cable including in combination
`a number of conductor pairs, each of which includes
`two conductors twisted together along a course which
`is a helix, and each pair having the pitch of its helix dif
`ferent from that of the other pairs, the helix differences
`being greater than 0.15 inch, means holding the pairs
`bundled together in a unit, a conducting shield around
`the unit, a plurality of like units shielded from one an
`other by their respective shields and cabled together to
`form a core for the cable, and a common enclosure sur
`rounding all of the units and holding them together in
`the communication cable.
`2. The communication cable described in claim 1
`characterized by all of the shields of the units having an
`outer covering by which the shields are insulated from
`one another and each of said shields being individually
`grounded.
`3. The communication cable described in claim
`characterized by all of the units being of the same con
`struction and having the same helix pitches.
`4. The communication cable described in claim
`characterized by the common enclosure being an over
`all conducting shield, and means holding the units to
`gether to form the core of the cable including a wrap
`by which the overall conducting shield is insulated from
`the units.
`5. The communication cable described in claim 4
`characterized by the overall shield being made of metal
`and insulated from the shields of the units.
`6. The communication cable described in claim
`characterized by the shield of each unit being a metal
`strip folded longitudinally around the bundle of pairs
`and covered with insulation.
`7. The communication cable described in claim
`characterized by the pairs of each unit being cabled by
`twisting them together, and a foamed jacket locking
`said pairs in their relation to one another to prevent dis
`tortion of their helixes during processing and installa
`tion of the cable.
`8. The communication cable described in claim 7
`characterized by the foamed jacket being an extrudate
`covering the cabled pairs of the unit under the conduct
`ing shield of the unit.
`9. The communication cable described in claim
`characterized by the cable being connected in a com
`munication line with some of the units transmitting
`messages in one direction and others transmitting mes
`sages in the opposite direction.
`10. The communication cable described in claim
`characterized by each of the units being in effect an in
`dividual cable with a metal shield insulated from the
`shie is cf the other units, said shields being continuous
`through cable splices and being carried at terminations
`into the housings of repeaters.
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