US1271824A - Telephone and telegraph cable. - Google Patents

Description

G. A. ANDEREGG 61 W. E. MUUGEY.

TELEPHONE AND YELEGRAPH CABLF.

APPLICATION HLLU JUNE 30. IQIb.

lntvntvd July 9, 1918.

UNITED STATES PATENT OFFICE.

GUSTAVUS A. ANDEREGG, OF OAK PARK, AND WILBUB E. MOUGEY, OI? CHICAGO, ILLINOIS, ASSIGNOBS TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATIQN OF NEW YORK.

TELEPHONE L'ND TELEGRAPH CABLE.

Specification of Letters Patent.

Patented July 9, 1918.

Application filed June 30, 1916. Serial 1T0. 106,808.

formed by twisting together two insulated conductors, and when two such airs are twisted together, there is forme what is known as quad. Each pair of conductors in silch a quad constitutes a side circuit or physical circuit, while each pair of conductors in parallel forms one side of a phantom circuit. The twist by which two conductors are combined to form a pair is called a pair twist, and the twist by which two pairs are combined to form a quad is called a quad twist. Cables containing one or more quads, with or without additional conductors, are known as duplex cables, and those containing no quads are known as non-duplex cables.

The object of this invention is the production of duplex cable exhibitin substantial improvements in the electrical charproduction of cable high elficient in the transmission of electrical impulses over the conductors therein.

Preferably, this is accomplished b employing quads having quad twists s orter than the twists of one or both of the pairs forming the respective quads, and proportionin the lengths of twist or lengths'of lay o the quads and pairs, so that the mutual capacityjwfboth the pair and phanacteristics thereof, thereby resulting in the tom circuits. and the capacity unbalance between the pairs in the same quad and between circuits in adjacent q ads, are greatly decreased. 0

The two pairs of a quad may be twisted in the same direction orin reverse direction to each other. Also the quad twists may be in same direction or in reverse direction to one or both of the pair twists.

This invention will be more fully understood from the following description, reference being made to the accompanying drawing, wherein Figure 1 shows a quad having. the same direction of quad and pair twists; Fig. 2 shows a quad having a direction of quad twist reverse. to that of the pairs; and Fig. 3 is a view in perspective of a multi-conductor cable, one quad of which is shown extending from the end thereof.

As shown in the drawing, the quads 10 are formed by twisting together two pairs 11, each of which is com osed of two conductors 12 of any desire gage. The conductors are preferably of copper, and are commonly covered with paper insulation 13 applied in a well-known manner. In Fig.

'3 is shown a plurality of quads 10 arranged in core or cable form and inclosed in a lead sheath 14.

It is generally recognized in the manufacture of non-duplex cable that it is desirable froma transmission standpoint to have adjacent pairs of difi'erent lengths of twist. In the manufacture of duplex cable, the two pairs forming a quad may or may not have different lengths of twist. However, when the two pairs of a quad have the same lengths of twist, it. is essential that the two pairs be twisted in reverse directions, that is, one pair of the quad should be twisted in a right-hand directionand the other pair of the quad should be twisted in a lefthand direction. The quad twists of adjacent quads should in all cases be of different lengths regardless of the relative lengths of the pair twists. This invention contem plates cables in which adjacent quads have difl'erent lengths of quad twists, the pairs in adjacent quads having different lengths of twist, and the pairs of the same uad having the same or difi'erent lengths o twist.

The mutualcapacity of pairs and phantoms depends to a. large entent upon the lengths of pair and quad twists used. In general, for a given number of quads, of a given gage of wire, within a given size sheath, lower mutual capacity ofpairs and phantoms can be obtained wlth long twists than with short twists.

When very long pair twists are used with quad twists of moderate length the mutual capacities of both pairs and phantoms are. in general, reduced by this lengthening of the pair twists. Lengthening of the tual capacity of the pairs.

The unbalance and the resultm crosstalk between a circuit in one qua and a circuit in-' an adjacent-quad is, in general,-

increased ifthe twists of the circuits involved are lengthened. It is especially true that the unbalanceand the resultin crosstalk between a phantom circuit e125 3 cireuit in an adjacent quadis increas if the length of the quad twist is increased. The unbalance and the resultin crosstalk between pair in one quad an a circuit in an adjacent uad is much less subject to increase wit increased length of pair twists. In addition, the unbalance and the result ing crosstalk between circuits in adjacent quads are, in general, greatest if the two circuits are phantoms and least if the two circuits are pairs. The unbalance involving a hantom circuit of one quad and a physical circuit of an adjacent quad, is in neral intermediate in magnitude between t at involving two phantom circuits and that involving two hysical circuits.

From the acts as above set forth it will be seen that there is generally a greater imrovement produced in mutual capacity by engthening the pair twists than by lengthening the quad twist. It is also seen that lower unbalance and crosstalk are produced with lengthened pair twists than with lengthened quad twist. It will therefore be seen that both from the standpoint of mutual capacit and from the standpoint of capacity an alance and crosstalk, it is preferable to lengthen the pair twists rather than to lengthen the quad twist.

An extended series of experiments has conclusively proven that duplex cables made .up in accordance with this invention exhibit 3. A grou of four insulated conductors 0 four insulated conductors.

.about each other with a consisting 0 two pairs helically twisted to;

gether to form a quad having pair twists longer than the quad twists, said pair an quad twists being in reverse direct1ons.

4. In a cablei a pluralit of insulated conductors forms into qua s each quad consisting of two pairs, one 0 said pairs having lengths of twist longer than the quad twists. I

5. A multi-conductor cable containing one or more quads, each quad consisting of two pairs havin relatively long lengths of twist twisted he ically about each other with a uniform length of lay less than that of one of the twisted pairs.

In witness whereof we hereunto subscribe our namw this 22nd day of June, A. D.,

GUSTAVUS A. ANDEREGG. WILBUR E. MOUGEY.

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