1. Field of Invention
This application is Application directed to a high speed data cable configured to improve alien crosstalk isolation between adjacent cables and/or improved crosstalk between twisted pairs of a cable.
2. Discussion of Related Art
High-speed data communications media include pairs of wire twisted together to form a balanced transmission line. Such pairs of wire are referred to as twisted pairs. One common type of conventional cable for high-speed data communications includes multiple twisted pairs that may be bundled and twisted (cabled) together to form the cable. There are two general categories of twisted pair cables: unshielded twisted pair (UTP) cables and shielded twisted pair (STP) cables, each of which has advantages and disadvantages. For some applications, the preferable cabling structure is “unshielded twisted pair” (UTP) cabling, meaning that the individual twisted pairs making up the cable do not have individual shielding layers. UTP is often preferred over shielded cables (and over optical fiber cables) because it is easier to install and more cost-effective.
Modern communication cables must meet electrical performance characteristics required for transmission at high frequencies. The Telecommunications Industry Association and the Electronics Industry Association (TIA/EIA) have developed standards which specify specific categories of performance for cable impedance, attenuation, skew and crosstalk isolation. When twisted pairs are closely placed, such as in a cable, electrical energy may be transferred from one pair of a cable to another. Such energy transferred between pairs is referred to as crosstalk and is generally undesirable. When two or more cables are stacked close together, or bundled together in a common outer sheath, an additional problem of crosstalk between twisted pairs in adjacent cables can occur. This is known as “alien” crosstalk. The TIA/EIA has defined standards for crosstalk, including TIA/EIA-568A. The International Electrotechnical Commission (IEC) has also defined standards for data communication cable crosstalk, including ISO/IEC 11801. One high-performance standard for 100Ω cable is ISO/IEC 11801, Category 5e, another is ISO/IEC 11801 Category 6.
Ethernet is now the most widely used network protocol in the world and there is an ever-increasing need in the industry for cables capable of reliable Ethernet data transmission at higher and higher transmission rates. A few years ago, transmission rates of a few Megabits per second (Mbps) were considered the state of art. However, transmission rates of more than ten Gigabits per second (Gbps) are now expected. The higher the desired transmission rate of data through a cable, the more critical becomes controlling effects such as crosstalk, skew and attenuation. Accordingly, a new 10 Gbps Ethernet over UTP standard for enhanced category 6 cables is being developed. One critical factor that needs to be addressed in the design of enhanced category 6 cables cable of 10 Gbps transmission rates is alien crosstalk. Alien cross-talk coupling, from the outside of the cable into the twisted pairs, is statistical and cannot be compensated for by adaptive amplifier techniques. Therefore, it is important to address alien crosstalk in the design of the cable itself.
To further reduce crosstalk between twisted pairs within a cable, some cables include a pair separator disposed between the twisted pairs to shield and/or isolate the twisted pairs from one another. For example, U.S. Pat. No. 6,222,130 describes a cable that includes four twisted pair media radially disposed about a “star”-shaped core. Each twisted pair nests between two fins of the “star”-shaped core, being separated from adjacent twisted pairs by the core. This helps reduce and stabilize crosstalk between the twisted pair media.
Some effort has been made in the prior art to reduce the effect of alien cross-talk on signal pairs in data cables. For example, some data communication cables include outer jackets having irregular or asymmetrical structures, as shown in
The shape of cable jacket 100 prevents symmetric stacking of flat data communication cables, when such cables are installed in ducts, troughs, and locations close to the cross-connect panels. Otherwise, the flat cables may automatically arrange, align and stack themselves in near perfect alignment due to their flat or rectangular shape. Such arrangement or flat cables increases alien cross-talk because the location of the twisted pairs within a flat cable jacket is parallel and the twisted pairs with the same twist lays or directions would be frequently separated only by the jacket material surrounding each cable.
However, a drawback to the shaped-jacket method of controlling alien crosstalk is that it is not always convenient or desirable to manufacture cables with irregularly-shaped outer jackets such as the cable jacket shown in
Aspects and embodiments of the present invention are directed to a separator structure that acts to reduce alien crosstalk between similar twisted pairs in cables that are in close proximity to one another.
According to one embodiment, a high speed data cable comprises a first twisted pair of insulated conductors, a second twisted pair of insulated conductors, and a separator positioned so as to separate the first twisted pair from the second twisted pair. The cable also comprises a jacket disposed about the first and second twisted pairs and the separator. According to one aspect, the separator comprises a central arm and at least one enlarged portion positioned at one end of the central arm and positioned at least partially around the first twisted pair of insulated conductors so as to create an outward projection of the jacket.
According to another embodiment, a high speed data cable comprises a first twisted pair of insulated conductors, a second twisted pair of insulated conductors, and a separator positioned so as to separate the first twisted pair from the second twisted pair. The cable also comprises a jacket disposed about the first and second twisted pairs and the separator. According to one aspect, the separator comprises a central arm and substantially symmetrical enlarged portions positioned at opposing ends of the central arm.
According to another embodiment, a cable comprises a first twisted pair of insulated conductors, a second twisted pair of insulated conductors, a separator positioned so as to separate the first twisted pair from the second twisted pair, and a jacket disposed about the first and second twisted pairs and the separator, wherein the separator comprises a central arm and symmetrical enlarged portions positioned at opposing ends of the central arm. In one example, the separator comprises a first ball formed on a first end of the central arm, and a second ball formed on a second, opposite end of the central arm, and wherein the first and second enlarged portions are similarly sized and equidistant from a center of the central arm.
According to one embodiment, a high speed data cable comprises a plurality of twisted pairs of insulated conductors including a first twisted pair, a second twisted pair and a third twisted pair, a shaped filler including a body portion and a plurality of tines extending outward from the body portion, the plurality of tines defining a plurality of channels in which the plurality of twisted pairs of insulated conductors are individually disposed, and an outer jacket surrounding the plurality of twisted pairs of insulated conductors and the shaped filler along a length of the cable. The shaped filler is constructed such that the body portion provides a first spacing between the first twisted pair and the second twisted pair and one of the plurality of tines provides a second spacing between the second twisted pair and the third twisted pair, the second spacing being substantially smaller than the first spacing. According to aspects of this embodiment of the invention, the body portion is constructed so as to provide a helical circumferential barrier extending along a length of the cable to facilitate reduction of alien crosstalk.
According to another embodiment, a high speed data cable comprises a first twisted pair of insulated conductors, a second twisted pair of insulated conductors, a third twisted pair of insulated conductors, a fourth twisted pair of insulated conductors, and a jacket disposed about the first, second, third, and fourth twisted pairs of insulated conductors. According to this embodiment, the first twisted pair, the second twisted pair, the third twisted pair and the fourth twist pair make up a core of the cable, and the core is helically wrapped with a dielectric rod.
According to another embodiment, a high speed data cable comprises a first twisted pair of insulated conductors, a second twisted pair of insulated conductors, a third twisted pair of insulated conductors, a fourth twisted pair of insulated conductors, and a jacket disposed about the first, second, third, and fourth twisted pairs of insulated conductors. According to this embodiment, the first twisted pair, the second twisted pair, the third twisted pair and the fourth twist pair make up a core of the cable, and the core is oscillated about the center of the cable within the jacket.
According to another embodiment, a high speed data cable comprises a first twisted pair of insulated conductors, a second twisted pair of insulated conductors, a third twisted pair of insulated conductors, a fourth twisted pair of insulated conductors, and a jacket disposed about the first, second, third, and fourth twisted pairs of insulated conductors. According to this embodiment, the first twisted pair, the second twisted pair, the third twisted pair and the fourth twist pair make up a core of the cable, and the jacket is extruded along the length of the cable with substantially the same thickness and with varying tightness to the core of the cable.
The accompanying drawings, are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:
Various embodiments and aspects of the invention will now be described in detail with reference to the accompanying figures. It is to be appreciated that this invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of the words “including,” “comprising,” “having,” “containing,” or “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
Some aspects and embodiments of the present invention are directed to a twisted pair cable including a shaped filler that defines channels in which the twisted pairs are located. The shaped filler holds the twisted pairs in a predefined relationship with one another, and may help to reduce crosstalk between twisted pairs and/or impedance non-uniformities. In addition, according to other aspects of the invention, the shaped filler may cause the cable to have a non-uniform outer circumference, resulting in non-equidistant spacing between adjacent cables, as discussed further below.
Other aspects and embodiments of the present invention are directed to a twisted pair cable including filler that provides for non-equidistant spacing between twisted pairs in adjacent cables and reduced alien crosstalk between adjacent cables, as discussed further below.
Other aspects and embodiments of the present invention are directed to a twisted pair cable including a dielectric rod about a circumference of the cable that provides for non-equidistant spacing between twisted pairs in adjacent cables and reduced alien crosstalk between adjacent cables, as discussed further below.
Other aspects and embodiments of the present invention are directed to a twisted pair cable including core that is spiraled about the center of the cable within a jacket of the cable that provides for non-equidistant spacing between twisted pairs in adjacent cables and reduced alien crosstalk between adjacent cables, as discussed further below.
Other aspects and embodiments of the present invention are directed to a twisted pair cable including a jacket that provides for varying regions of tightness of the jacket about a core of the cable and that provides for non-equidistant spacing between twisted pairs in adjacent cables and reduced alien crosstalk between adjacent cables, as discussed further below.
Cables according to various embodiments of the present invention may be used in all cable applications, including but not limited to, data or voice network applications (e.g., cables connecting computers, telephones or other data network components), local area networks (LANs), Ethernet applications, and a variety of other cable applications.
Aspects of the present invention relate to an unshielded twisted pair (UTP) cable capable of meeting the requirements for 10 Gigabit per second (Gbps) data transmission rates. Embodiments of the invention include a UTP cable comprising a separator that lies between twisted pairs in the cable and is designed to reduce alien crosstalk effects from nearby or adjacent cables.
As discussed above, crosstalk between twisted pairs in a twisted pair data cable, and alien crosstalk between twisted pairs in co-located cables are of particular concern to designers of high performance, high speed data cables. The present invention offers solutions to the problems of crosstalk and alien crosstalk through the use of novel shaped fillers.
Referring to
Separators present in conventional cables may have numerous different shapes and may be folded and arranged within the outer jacket so as to separate one or more twisted pairs from other twisted pairs in the cable. For example, U.S. Pat. No. 6,570,095 to Clark et al discloses several arrangements of tape separators. Other separators may be, for example, star-shaped, such as the separator disclosed in U.S. Pat. No. 6,222,130 to Gareis, or cross-shaped, such as the separator disclosed in U.S. Pat. No. 5,969,295 to Boucino et al. These separators, regardless of shape or material, are generally used to prevent physical contact between opposite and adjacent twisted pairs, and the primary function of these separators is to reduce crosstalk between twisted pairs within a cable. However, such separators may have little or no effect on alien crosstalk between twisted pairs in neighboring cables.
In many circumstances, cables may be bundled together or may be placed in close proximity, for example, inside a conduit. As discussed above, alien crosstalk among such cables in close proximity is an important concern in the design of high speed data cables. Referring to
As shown in
In the above and similar circumstances, alien crosstalk can occur between two closely spaced twisted pairs in adjacent cables when the two closely spaced twisted pairs have similar twist lays. For example, two cables may be manufactured, each comprising four twisted pairs of insulated conductors, the twisted pairs having twist lays approximately as shown in Table 1.
It is to be appreciated that the twist lays given in Table 1 are exemplary only and not intended to be limiting. It is also to be appreciated that, due to manufacturing tolerances, the actual twist lays of the individual twisted pairs in different cables may be slightly different that the exemplary values given in Table 1. However, alien crosstalk can occur not only between twisted pairs with identical twist pays, but also between twisted pairs with similar twist lays. Therefore, as can be seen from Table 1 and
According to one embodiment, there is provided a separator that may be positioned between twisted pairs in a cable and that serves to reduce alien crosstalk between similar twisted pairs in adjacent cables. Referring to
In addition, it is also to be appreciated that the cable may comprise any number of twisted pairs (not limited to four pairs as illustrated) and the twisted pairs 118 may be positioned about the separator 120 in any desired configuration (not limited to the illustrated example of two pairs on either side of the separator).
As shown in
Referring to
According to one embodiment, illustrated in
Referring to
According to one embodiment of the invention, the separators 138a, 138b are provide with at least one enlarged portion 136a, 136b, which are disposed so that they are situated adjacent to the twisted pairs of conductors having the shortest twist lays (illustrated as 140a, and 142a in
Thus, the separators 138a, 138b according to aspects of the invention may reduce alien crosstalk between similar twisted pairs in adjacently situated cables by increasing the spacing between such twisted pairs. Advantageously, according to some aspects of the invention, the separator may achieve a reduction in alien crosstalk without modification to the cable jacket. However, it is also to be appreciated that the jacket may be formed with a plurality of protrusions extending away from an inner circumferential surface of the jacket such as disclosed in commonly owned U.S. Pat. No. 7,135,641 which is herein incorporated by reference, wherein the plurality of protrusions cause the plurality of twisted pairs of insulated conductors to be kept away from the inner circumferential surface of the jacket, and serve a similar purpose as the herein described embodiments of the separator.
It is to be appreciated that cables according to aspects of the invention can be constructed using a number of different materials for the twisted pair insulations, the separator and the cable jacket. For example, the separator according to aspects of the invention may comprise one or more of many different materials, conductive or non-conductive, flame retardant or not. For example, the separator may include a flame-retardant, low-dielectric constant, low-dissipation factor polymer, which may be foamed in some examples. In one example, the separator may comprise a foamed flame retardant, cellular polyolefin or fluoropolymer like NEPTC PP500 “SuperBulk”, a foamed fluorinated ethylene propylene (FEP) or a foamed polyvinyl chloride (PVC). For plenum-rated cables, the separator may include materials with flame retardant and/or smoke-suppressive properties or additives. The separator may also be constructed from a variety of other materials, including, but not limited to a bulk filling material such as a polyolefin or glass fiber filler, conductive materials, or partially conductive materials, such as a dielectric with a conductive coating or filling. In addition, the outerjacket 122 can be made from various materials including, for example, polyvinylchloride (PVC), low-smoke, low-flame PVC, or any plenum or non-plenum rated thermoplastic. Similarly, the twisted pairs may be insulated with any suitable insulation material, as known to those skilled in the art. It is to be appreciated that the above examples of materials are given as examples only and the invention is not limited to the use of these materials.
Further, as mentioned above, separators according to various aspects of the invention may have various different shapes and are not limited to the specific shape illustrated in
For example, referring to
In addition, it is also to be appreciated that the cable may comprise any number of twisted pairs (not limited to four pairs as illustrated) and the twisted pairs 174 may be positioned about the separator 172 in any desired configuration (not limited to the illustrated example of two pairs on either side of the separator as illustrated in
As shown in the embodiment illustrated in
It is to be understood that there are two modes of alien crosstalk reduction between adjacently situated cables that can be achieved with the various embodiments of the invention described herein. As has been discussed above,
According to another embodiment as illustrated in
It is to be appreciated that numerous shapes other than those illustrated are possible for the separators described herein, as may be apparent to those skilled in the art. For example, the separator may include enlarged portions that are not round, but instead have, for example, a squarish shape or any other of a multitude of shapes. The separator may also include numerous other arm portions, for example to separate twisted pairs within the cable when the cable comprises more than four twisted pairs. Furthermore, it is to be appreciated that according to any of the embodiments of the cables described herein, the jacket may be formed with a plurality of protrusions extending away from an inner circumferential surface of the jacket such as disclosed in commonly owned U.S. Pat. No. 7,135,641 which is herein incorporated by reference, wherein the plurality of protrusions cause the plurality of twisted pairs of insulated conductors to be kept away from the inner circumferential surface of the jacket, and serve a similar purpose as the herein described embodiments of the separator. It is to be understood that the invention is not limited to any specific shape of the separator. It is preferred that the separator provide at least one enlarged portion (of whatever shape) to create an oblong or oval or non-rounded shaped jacket, and in some embodiments that the separator contain the twisted pairs toward the center of the cable, as viewed when the cable is helically twisted (as in
Referring to
In one embodiment, the filler 214 includes a base portion 220 and a plurality of tines 222 that define channels 224 in which one or more twisted pairs 212 may be located. According to one preferred embodiment, each twisted pair 212 is individually located in a channel 224, such that each twisted pair is separated from other twisted pairs in the cable by a portion of the filler 214, e.g., by a tine 222 or by some of the base portion 220. Thus, the filer 214 serves to separate the twisted pairs from one another any may reduce crosstalk between the twisted pairs.
As discussed above, the twisted pairs 212 may have different twist lays from one another. For example, in one embodiment, the twisted pairs may have twist lays approximately as those shown below in Table 2.
It is to be appreciated that the twist lays given in Table 2 are exemplary only and not intended to be limiting. It is also to be appreciated that, due to manufacturing tolerances, the actual twist lays of the individual twisted pairs in different cables may be slightly different that the exemplary values given in Table 2. However, crosstalk can occur not only between twisted pairs with identical twist pays, but also between twisted pairs with similar twist lays. Thus, in one example, the twisted pairs may be arranged about the filler 214 as shown in
Crosstalk between twisted pairs is inversely proportional to the distance separating the twisted pairs. Furthermore, crosstalk is diminished by the presence of a dielectric barrier material or conductive shield between twisted pairs. Therefore, by placing a large portion of the filler between twisted pairs, crosstalk between those twisted pairs is reduced because the pairs are spaced apart from one another and separated from one another by the filler. In addition, because a large portion of the filler may be disposed between twisted pairs with similar twist lays, a delta between the twist lays of two similar twisted pairs may be reduced without a negative impact on the crosstalk between those twisted pairs.
It is to be appreciated that the present invention is not limited to the embodiments illustrated in the figures. For example, the filler 214 is not limited to the shape illustrated in
It is further to be appreciated that cables according to aspects of the invention can be constructed using a number of different materials for the twisted pair insulations, the filler and the cable jacket. For example, the filler according to aspects of the invention may comprise one or more of many different materials, and may be conductive or non-conductive, flame retardant or not. For example, the filler may include a flame-retardant, low-dielectric constant, low-dissipation factor polymer, which may be foamed in some examples. In one example, the separator may comprise a foamed flame retardant, cellular polyolefin or fluoropolymer like NEPTC PP500 “SuperBulk”, a foamed fluorinated ethylene propylene (FEP) or a foamed polyvinyl chloride (PVC). For plenum-rated cables, the filler may include materials with flame retardant and/or smoke-suppressive properties or additives. The filler may also be constructed from a variety of other materials, including, but not limited to a bulk filling material such as a polyolefin or glass fiber filler, conductive materials, or partially conductive materials, such as a dielectric with a conductive coating or filling. In shielded twisted pair cables including the optional shield 218, it may be particularly advantageous to form the filler 214 of a conductive or partially conductive material. In addition, the outer jacket 222 can be made from various materials including, for example, polyvinylchloride (PVC), low-smoke, low-flame PVC, or any plenum or non-plenum rated thermoplastic. Similarly, the twisted pairs may be insulated with any suitable insulation material, as known to those skilled in the art. It is to be appreciated that the above examples of materials are given as examples only and the invention is not limited to the use of these materials.
According to another embodiment, the filler 214 may be constructed so as to define an interior channel 230 in the base portion 232, as shown in
Referring to
In one example, the opening 244 of the channels 224 may be narrowed by the flange portions 240 of the tines 236 to slightly smaller than a diameter 246 of the circular space occupied by the twisted pairs 212. The material of the filler 214 may be slightly flexible so as to allow the twisted pairs to be “snapped” or pressed into the channels 224. The twisted pairs 212 are thus securely held in their respective channel 224 and may not be able to easily fall out of the channel when the cable is handled (for example, during installation or termination). This embodiment may offer an additional advantage in that the twisted pairs are securely held in a predetermined configuration, at controlled, defined spacing from one another, which may improve the impedance uniformity of the cable. In one example, the filler 214 may include an interior opening 230, as discussed above.
According to another embodiment, the shaped filler may be constructed such that when the cable core is cabled and when the jacket 216 is applied over the cable core, the filler 214 causes the outer circumference of the jacket to be non-uniform, e.g., non-circular. This effect may be achieved by controlling the shape of the body portion 220 of the filler and the location of the tines 222. A non-uniform outer circumference for the jacket 216 is advantageous in that it may prevent aligned stacking of multiple cables, which may serve to reduce alien crosstalk between twisted pairs in adjacent or nearby cables. In addition, when the cable is helically twisted about its longitudinal axis (which occurs as part of the cabling procedure when the twisted pairs and the separator are cabled together and jacketed), the body portion forms a helical wall or barrier around the circumference of the cable along its length. In other words, when the above-described embodiments of the filler is cabled with the twisted pairs of conductors and a jacket, the larger body part of the filler (220, 232, 234) provides for a larger portion that forms a helical barrier to alien crosstalk with adjacent cables along the length of the cable. Thus, it is to be appreciated that these embodiments of the filler also provide the reduced alien cross talk effect as the other herein described embodiments of the invention. It is also to be appreciated that the jacket for such embodiment may be formed with a plurality of protrusions extending away from an inner circumferential surface of the jacket such as disclosed in commonly owned U.S. Pat. No. 7,135,641 which is herein incorporated by reference, wherein the plurality of protrusions cause the plurality of twisted pairs of insulated conductors to be kept away from the inner circumferential surface of the jacket, and serve a similar purpose as the described embodiments of the separator.
According to another embodiment of the invention, any of the herein described cables, whether previously known or those according to the invention, can be provided with at least one contra helically wrapped rod about a circumference of the cable (not illustrated). The rod can be any dielectric for an UTP cable (and could be metallic if cable includes a shield) that is wrapped around the core of the UTP cable. By core, it is understood that the core comprises the twisted pairs of conductors, any separator if one is provided in the cable, and an optional binder to keep the twisted pairs and any separator together. The at least one dielectric rod is helically wrapped around the core, for example, in a clockwise direction to provide a barrier between the core of the cable and the jacket. It is to be appreciated that an advantage of this embodiment of the invention is that the rod helps to reduce signal attenuation effects that result, for example, from the jacket, and also helps to reduce alien crosstalk based on the principles that have been described herein. According to this embodiment, the cable (core, rod, jacket etc.) is cabled in a direction opposite to the helical wrapping of the rod, for example, in an anti-clockwise direction for the rod wrapped in the clockwise direction. Because the rod twist and the cable lay are in opposite directions, the rod is “contra-helically” wrapped.
It is to be appreciated that variations to this embodiment can also be provided such as multiple rods can also be applied in opposite directions, for example, in a crosshatch pattern. It should also be understood that the at least one rod can be applied in a varying lay, for example, over a range from about 0.5 inches to about 30 inches. Also, it is to be appreciated that according to some aspects, the rod may be secured to the core of the cable. Furthermore, it is to be appreciated that the jacket may be formed with a plurality of protrusions extending away from an inner circumferential surface of the jacket such as disclosed in commonly owned U.S. Pat. No. 7,135,641 which is herein incorporated by reference, wherein the plurality of protrusions cause core of the jacket to be kept away from the inner circumferential surface of the jacket, and serve a similar purpose as the contra-helically wrapped rod. It is to be further appreciated that according to some aspects of the invention, this “contra-helically” wrapped cable can be manufactured in one operation or in other words at the same time. For example, an applicator for extruding the dielectric rod can be configured to spin in the opposite direction of the cable lay during the cabling operation.
According to another embodiment of the invention, any of the herein described cables, whether previously known or those according to the invention, can be provided with at least one helically wrapped rod (wrapped in the same direction as the cable is twisted) about a circumference of the cable (not illustrated). The rod can be any dielectric for an UTP cable (and could be metallic if cable includes a shield) that is wrapped around the core of the UTP cable. By core, for this embodiment too, it is understood that the core comprises the twisted pairs of conductors, any separator if one is provided in the cable, and an optional binder to keep the twisted pairs and any separator together. The at least one dielectric rod is helically wrapped around the core, for example, in a clockwise direction to provide a barrier between the core of the cable and the jacket. It is to be appreciated that an advantage of this embodiment of the invention is also that the rod helps to reduce signal attenuation effects that result, for example, from the jacket, and also helps to reduce alien crosstalk based on the principles that have been described herein. For this embodiment, it is understood that the cable (core, rod, jacket etc.) is cabled in a same direction as the helical wrapping of the rod.
It is to be appreciated the at least one rod can be applied in a varying lay, for example, over a range from about 0.5 inches to about 30 inches. Also, it is to be appreciated that according to some aspects, the rod may be secured to the core of the cable. It is to be further to be appreciated that the jacket may be formed with a plurality of protrusions extending away from an inner circumferential surface of the jacket such as disclosed in commonly owned U.S. Pat. No. 7,135,641 which is herein incorporated by reference, wherein the plurality of protrusions cause the plurality the core of the cable to be kept away from the inner circumferential surface of the jacket, and serve a similar purpose as the helical wrapped rod. It is to be further appreciated that according to some aspects of the invention, this “helically” wrapped cable can be manufactured in one operation or in other words at the same time. For example, an applicator for extruding the dielectric rod can be configured to spin in the direction of the cable lay during the cabling operation. According to some aspects, the “twist lay” of the rod about the core can be configured to substantially match the cable lay. Alternatively, according to another aspect an applicator can be configured to spin faster than the cable core in the direction of the cable lay during the cabling operation so as to provide for a rod wrap length or lay that is shorter than the cable lay.
According to another embodiment of the invention, any of the previously known or herein described cables according to the invention, can be provided as an oscillating core within a jacket.
According to another embodiment of the invention, any of the previously known or herein described cables according to the invention, can be provided as an oscillating core within a jacket (not illustrated). By core, for this embodiment too, it is understood that the core comprises the twisted pairs of conductors, any separator if one is provided in the cable, and an optional binder to keep the twisted pairs and any separator together. According to this embodiment, a jacket having an undulating wall tightness about the core is provided along the length of the cable. The jacket preferably has substantially the same thickness, and is provided so that the jacket moves from in contact with the core to away from the core. This jacket may be provided during extrusion of the jacket so that in some areas (lengthwise along the cable), the jacket is tightly held to the core, whereas in other areas, it's held more loosely during formation so that it is less tight about the core, so that the size of the outer circumference of the jacket changes, but the jacket thickness remains substantially the same. According to some aspects, the frequency of the undulations are random, thereby reducing any periodicity that may cause structural return loss and attenuation issues. Furthermore, it is to be appreciated that the jacket may be formed with a plurality of protrusions extending away from an inner circumferential surface of the jacket such as disclosed in commonly owned U.S. Pat. No. 7,135,641 which is herein incorporated by reference, wherein the plurality of protrusions cause the core to be kept away from the inner circumferential surface of the jacket, and serve a similar purpose as the undulating jacket tightness.
Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.
This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 60/749,179, entitled “TWISTED PAIR CABLE HAVING IMPROVED CROSSTALK ISOLATION,” filed on Dec. 9, 2006, which is herein incorporated by reference in its entirety.
Number | Date | Country | |
---|---|---|---|
60749179 | Dec 2005 | US |