Patent Application
20220392666
The disclosed subject matter relates generally to data cabling.
Many types of data cables, including category-rated cables or other types of networking cables, carry multiple twisted conductor pairs so that a plurality of data signals can be routed via a single cable. Although the twisting of each pair of conductors can reduce signal interference due to internal crosstalk between the pairs, the conductor pairs may still be susceptible to some degree of crosstalk due to their proximity to one another within the cable jacket. Moreover, high-density installations may experience alien crosstalk between cables that run in close proximity to one another, particularly when unshielded twisted pair (UTP) cables are used.
The above-described deficiencies of current data cables are merely intended to provide an overview of some of the problems of current technology and are not intended to be exhaustive. Other problems with the state of the art, and corresponding benefits of some of the various non-limiting embodiments described herein, may become further apparent upon review of the following detailed description.
The following presents a simplified summary of the disclosed subject matter in order to provide a basic understanding of some aspects of the various embodiments. This summary is not an extensive overview of the various embodiments. It is intended neither to identify key or critical elements of the various embodiments nor to delineate the scope of the various embodiments. Its sole purpose is to present some concepts of the disclosure in a streamlined form as a prelude to the more detailed description that is presented later.
Various embodiments described herein provide a data cable design that offers a greater range of lay scheme options relative to conventional twisted pair cables, yielding a cable that can better mitigate the effects of internal and alien crosstalk while also satisfying signal propagation delay requirements. In one or more embodiments, the total set of twisted conductor pairs housed in the cable's jacket are segregated into two groups of twisted pairs, each group having at least two twisted conductor pairs. A dividing structure inside the jacket maintains physical separation between the resulting two groups of twisted pairs. In addition to the individual twistings applied to each twisted pair, each of the two groups of twisted pairs can be twisted together within the jacket, yielding two overall lay lengths which can be offset from one another to reduce the effects of crosstalk. In contrast to cable designs that only permit overall twisting of all enclosed twisted pairs as a single group, embodiments of the cable design described herein can permit two smaller subsets of the twisted conductor pairs to be twisted together independently of one another. The smaller cross-sectional diameters—and corresponding smaller circumferential distances—of the two twisted pair groups permits a smaller overall lay for the two groups relative to twisting all the pairs as a single group. These smaller overall lays can allow tighter twisting of the individual twisted pairs while keeping the total signal propagation distance within standards.
To the accomplishment of the foregoing and related ends, the disclosed subject matter, then, comprises one or more of the features hereinafter more fully described. The following description and the annexed drawings set forth in detail certain illustrative aspects of the subject matter. However, these aspects are indicative of but a few of the various ways in which the principles of the subject matter can be employed. Other aspects, advantages, and novel features of the disclosed subject matter will become apparent from the following detailed description when considered in conjunction with the drawings. It will also be appreciated that the detailed description may include additional or alternative embodiments beyond those described in this summary.
The subject disclosure is now described with reference to the drawings wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the subject disclosure. It may be evident, however, that the subject disclosure may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the subject disclosure.
The twist rate, or pitch, of each twisted pair 104 determines that pair's individual lay length. The lay length of a given conductor is the distance required for the conductor to complete one revolution about the axis of its twisted pair 104, and is therefore a function of the twist rate of the pair 104.
In addition to allowing the twist rate of each individual twisted pair 104 to be controlled, the design of cable 100 also allows the four twisted pairs 104 and the flexible cross member 106 to be twisted as a group about the axis of the cable 100. This twisting is referred to herein as twist B and is represented by the arrow in
The construction of cable 100 permits a number of design variables that affect the distances of the signal paths; namely, the individual lay lengths of the twisted pairs 104 (controlled by the pitch of twist A for each pair 104) and one overall lay length achieved by rotating the twisted pairs 104 and flexible cross member 106 about the axis of the cable 100. This overall lay length is determined by the pitch of twist B. These design variables can be set such that the electrical characteristics of the cable 100 satisfy safety and performance specifications. For example, in high density installations the proximity of cables 100 to one another can produce interference due to alien crosstalk between the cables 100. The effects of alien crosstalk can be reduced by making the lay lengths of the twisted pairs 104 tight and consistent. However, if an individual twisted pair 104 is twisted too tightly its electrical characteristics may deviate from specification requirements due to the corresponding increase of the total signal propagation distance, which must be kept below a maximum signal path distance in some use cases.
To address these and other issues, one or more embodiments described herein provide a data cable having an internal construction that introduces an additional lay length design variable and thus permits a greater range of lay scheme options. In one or more embodiments, a data cable comprising four twisted pairs 104 can be fabricated such that the twisted pairs 104 are segregated into two groups—referred to herein as quad units—that each comprise two twisted pairs 104. In addition to the individual conductor pair twists (twist A), each of the two groups of two twisted pairs 104 can be twisted independently of one another, improving the cable's ability to reject both internal and alien crosstalk interference. The smaller circumferential distance of each quad unit relative to that of overall twist B described above also allows each quad unit to have a smaller minimum overall lay if desired (approximately half the minimum lay length achieved by twist B), allowing for a greater range of design options when selecting a combination of individual pair and overall lay lengths that satisfy electrical specification requirements in terms of interference rejection, insertion loss, and propagation delay.
Each twisted pair 104 can be twisted individually as represented in
Since each quad unit can be twisted independently of one another, the cable can be manufactured such that twist X has a different pitch than twist Y, yielding two different lay lengths for the two quad units. In this regard, the two quad units can be considered two differing cables within the same cable jacket, each having a different overall lay length determined by the pitch of their respective group twists X and Y. This yields an additional design variable relative to cable 100, since the overall twist B of cable 100 is replaced with two smaller twists X and Y for the two quad units, each having a pitch that can be set independently of the other. This construction allows the electrical characteristics of each quad unit to be set independently of one another using different combinations of pitches for the individual twists A and group twists X or Y for each quad unit, allowing for a greater range of lay scheme options.
Different jacket designs can be used to house the twisted pairs 104 in a manner that allows the two quad units to be individually twisted as illustrated in
In the conjoined configuration illustrated in
The construction of cable 700 permits the same twisting options (twists A, X, and Y) illustrated in
Although only two example cables 500 and 700 that support independent twisting of quad units have been illustrated, other cable constructions capable of segregating a set of twisted pairs 104 into two smaller groups that can be twisted independently of one another are also within the scope of one or more embodiments.
The constructions of cables 500 and 700 offer a number of advantages relative to conventional twisted pair cables (such as cable 100). For example, the introduction of twists X and Y allows the two quad units—that is, the two sets of two pairs 104—to be treated as individual units whose electrical characteristics can be set independently of one another. In addition to allowing the pitch of each twist A to be set independently for each individual twisted pair 104, the pitches of twists X and Y for each group of two twisted pairs 104 can also be set independently of one another, allowing the twist rates of the two quad units to be offset from one another. Differentiating the pitches of twists X and Y can improve the electrical performance of the cables 500 and 700 by further reducing the effects of both internal crosstalk and alien crosstalk even if no shielding is used.
The additional design variables afforded by segregating the four twisted pairs 104 into two independent groups also permits a greater range of lay scheme options. For example, rather than manufacturing cable 500 or 700 such that the twist pitches of the individual twisted pairs 104 are offset from one another to a large degree in order to reduce the effects of internal crosstalk, the twists A of the individual twisted pairs 104 can be made to have equal or similar pitches to one another, while the pitches of twists X and Y for the two quad units can be offset to mitigate internal crosstalk, resulting in two different overall lays for the two quad units. This can simplify the problem of mitigating the effects of internal crosstalk by eliminating the need to introduce offsets between the lay lengths of individual twisted pairs 104.
In another example configuration, the individual twist A for one or more of the twisted pairs 104 can be made tighter to better reject crosstalk interference, resulting in a small individual pair lay, and this short individual pair lay can be compensated for using a longer overall lay for the quad unit in which the twisted pair 104 resides by using a long pitch for twist X or Y. Selecting a suitable combination of pitches for twists A and X or Y can yield a cable 500 or 700 that satisfies a maximum signal path requirement even if relatively tight individual pair twists A are introduced. That is, short lay lengths at either the individual pair level or the overall quad unit level can be compensated for by longer lay lengths at the other level.
Also, since the diameter of each quad unit is smaller than the diameter of the larger grouping of four twisted pairs 104, dividing the four twisted pairs 104 into two quad units reduces the helical distance of the resulting quad unit lays relative to the overall lays of conventional cables (e.g., cable 100).
The smaller overall lay of the quad units can offer a greater range of design options relative to cable 100. For example, for a given individual lay length for the twisted pairs 104, the overall lay length can be reduced to approximately half that of cable 100 while maintaining the same propagation delay and insertion loss. In another design example, if an overall lay length for a quad unit is made equal to that of a given cable 100, the individual lay lengths for the twisted pairs 104 can be reduced relative to those of cable 100 while maintaining the same propagation delay and insertion loss. This can further mitigate the effects of crosstalk interference by allowing tighter twisting on the individual twisted pairs 104 while maintaining the same overall signal propagation distance. Reducing the diameter from D1 to D2 allows the lay lengths of the individual twisted pairs 104 to be reduced while maintaining the same signal distance if desired, since the total distance that each conductor must travel to complete one rotation of the overall twist is reduced relative to the design of cable 100. In general, segregating the four twisted pairs 104 into two quad units that can be twisted independently within the same cable jacket effectively doubles the overall lay length options relative to cable 100, while also permitting offsets to be introduced between the twist pitches of the two resulting quad units.
According to another embodiment, the design of cable 700 can be modified to permit a tertiary twisting of the conductors in addition to the individual twists A and the quad unit twists X and Y.
Although examples described herein have considered cables that comprise four total twisted pairs 104 that are divided into two smaller quad unit groupings of two pairs per groups, this cable design principle can also be applied to cables having greater numbers of twisted pairs 104 without departing from the scope of this disclosure. For example, a six-pair cable can be designed such that the six twisted pairs are divided into two groups of three pairs per group, such that the resulting to groups of three twisted pairs can be twisted independently of one another within the cable jacket.
Embodiments of the data cable constructions described herein can offer cable designers greater flexibility with regard to cable lay options by introducing an additional design variable and by dividing the overall twist diameter D1 into two smaller twist diameters D2. The cable lay options afforded by these constructions can improve the cable's ability to reject interference due to internal and alien crosstalk even if no shielding is used (e.g., in unshielded twisted pair, or UTP, embodiments).
The above description of illustrated embodiments of the subject disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. While specific embodiments and examples are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such embodiments and examples, as those skilled in the relevant art can recognize.
In this regard, while the disclosed subject matter has been described in connection with various embodiments and corresponding figures, where applicable, it is to be understood that other similar embodiments can be used or modifications and additions can be made to the described embodiments for performing the same, similar, alternative, or substitute function of the disclosed subject matter without deviating therefrom. Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, but rather should be construed in breadth and scope in accordance with the appended claims below.
In addition, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. Moreover, articles “a” and “an” as used in the subject specification and annexed drawings should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.
What has been described above includes examples of systems and methods illustrative of the disclosed subject matter. It is, of course, not possible to describe every combination of components or methodologies here. One of ordinary skill in the art may recognize that many further combinations and permutations of the claimed subject matter are possible. Furthermore, to the extent that the terms “includes,” “has,” “possesses,” and the like are used in the detailed description, claims, appendices and drawings such terms are intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.
