MXPA98000866A - Wiring arrangement of a network for area lo - Google Patents

Abstract

The present invention relates to a cabling means which is suitable for data transmission with relatively low crosstalk including a plurality of metallic conductor pairs, each pair includes 2 insulated plastic metal conductors which are twisted together. The characterization of the twist is important and relates the parameters such as length of twist length / arrangement of the core strand. More specifically, particular combinations of twist lengths and length / arrangement of the core strand are purposely selected for each cable isolate in order to achieve the performance capabilities that significantly exceed those required under TIA / EIA-568A. In a particular embodiment of this invention, a cable comprises, as its transmission medium, four twisted pairs of individually insulated conductors with each of the insulated conductors including a metallic conductor and an insulating cover enclosing the metallic conductor. The joint twist of the insulated conductors of each pair is characterized as specifically set forth herein and the plurality of the transmission means are enclosed in a wrapping system which in the simplest mode may be a single liner made of a material of plastic. As a result of the particular twist scheme used for the insulated conductor pairs, the operational performance of the resulting cable is improved. Also, the cable of this invention is relatively easy to connect and is relatively easy to connect and install.

Description

WIRING ARRANGEMENT OF A NETWORK FOR LOCAL AREA FIELD OF THE INVENTION This invention relates to an improved array of local area network cabling, more specifically, it refers to a particular cable design which due to its unique construction is capable of providing data transmission at a high bit rate, substantially error-free, while also satisfying numerous operational, high performance criteria.

BACKGROUND OF THE INVENTION Along with the greatly increased use of office computers and manufacturing facilities, a need has developed for a cable that can be used to connect the peripheral equipment to the computers in the main unit and to connect two or more computers in the main unit. a common network. Of course, given the ever increasing demands for data transmission, the sought-after cable must not only desirably provide a substantially error-free transmission at speeds REF .: 26826 relatively high, but must also meet numerous operational performance criteria, high. Specifically, the particular cable design of the present invention performs consistently at operational levels that exceed the transmission requirements for cables that qualify as category 5 cables under TIA / EIA-568A. Among the high operational performance criteria that the cable of this invention can reliably and consistently exhibit on the existing normal criteria are high crosstalk margins, that is, at least about 10 dB of crosstalk at the near end (NEXT) and more or about at least about 8 dB for power summing crosstalk (NEXT PSUM), as well as improved margins of structure return loss (SRL), that is, more than at least about 3 dB. Not surprisingly, the speed and distances over which the data signals should be transmitted are of importance for the design of metallic conductor cables for use in local area networks. In the past, this need has been one for interconnections operating at data speeds of up to 20 kilobits per second and over a distance not exceeding approximately 150 feet. This need was met with individual liner cables which may comprise a plurality of insulated conductors that were directly connected between a computer, for example, and a receiving means such as peripheral equipment. In general, the equipment, generally identified throughout the industry as category 3 products, is commercially available, which can effectively transmit data signals up to 16 MHz and a series of products designated as a category. 5 provides the ability to effectively transmit data signals up to 100 MHz. However, additional advances in data rate capability are becoming increasingly difficult due to the amount of crosstalk between the conductor pairs of these cables of twisted pairs, individually, commercially available. Additionally, for both cost and operational reasons, it is important that if the system is arranged or not to provide the transmission in what is called a balanced mode. In transmission in balanced mode, the voltages and currents in the conductors of a pair are equal in amplitude, but opposite in polarity. To achieve this transmission in the balanced mode, additional components, such as transformers, may be required, for example, at cable end points between the logical devices and the cable, thereby increasing the cost of the system. Frequently, computer equipment manufacturers have preferred the use of systems characterized by an unbalanced mode to avoid investing in additional components for each line. Nevertheless, at the same time, the arrangements of the peripheral connections, specifically the wiring used in them, must satisfy predetermined attenuation and crosstalk requirements. As an alternative to a twisted-pair, single-sheathed cable, sometimes the wiring needs of the communications industry have been filled with coaxial cable comprising the well-known, solid outer, tubular conductor separated by a material dielectric. However, coaxial cables not only inherently provide an unbalanced transmission, but also present several different problems. Among other interests, coaxial connectors are relatively expensive and difficult to install and connect, and unless they are well designed, installed and maintained, they can be the cause of electromagnetic interference. Given their increasingly stringent objectives, customers, local area network (LAN) vendors, and distribution system vendors continue to explore alternatives for making LAN wiring more economical and manageable, while still providing the necessary level of transmission performance. Previously tolerated by researchers has been the twisted, unprotected pair used for a long time for the distribution of telephone signals in real estate. Twisted, unprotected torque has been used for a long time for telephone transmission in balanced (differential) mode. Used in this way, the twisted, unprotected pair has excellent immunity from interference either from the outside (EMI) or from signals in other pairs (crosstalk). Another point of interest is that the cable is designed not to emit electromagnetic radiation from the cable in the surrounding environment. During the last several years, in fact, some LAN designers have been realizing the latent transmission capacity of the twisted pair, unprotected wire.

Especially notable is the ability of the twisted pair to transmit digital, quantized, strong signals, compared to the corruptible analog signals. The limitations imposed by crosstalk, especially near-end crosstalk, on the data rate / distance capabilities of twisted-pair-pair cables are generally recognized. In an attempt to improve the operational design of the twisted pair cables, manufacturers have employed a variety of different twist schemes. As used herein, the twist scheme is synonymous with what in industry is sometimes called mating or pairwise wiring. In general, the twist scheme refers to the exact length and type / arrangement of the twist selected for each conductor pair. More specifically, in a twist scheme described particularly in commonly assigned U.S. Patent No. 4,873,393, issued in the names of Friesen and Nutt and which is expressly incorporated herein by reference, it is proposed that the twist length for each insulated conductor pair must not exceed the product of approximately forty and the outer diameter of the insulation of one of the pair conductors. While this is just one example of an existing approach to defining a twist scheme that results in an improved cable design, there are many others. However, the particular twist scheme disclosed and claimed herein is believed to be uniquely different from all existing cable designs with specific technical distinctions discussed in greater detail hereinafter. In addition to the controlled torque twist schemes, another treatment for crosstalk will be added, protecting each twisted pair to confine its electric and magnetic fields. However, since the electric and magnetic fields are confined, the resistance, capacitance and inductance all change, each in such a way as to increase transmission loss. For example, it is not unusual to find designs of protected pairs whose attenuation is three times that of unprotected, similar pairs. Apparently, prior art solutions to the problem of providing a local area network cabling arrangement that can be used to transmit, for example, error-free data bits at relatively high speeds over relatively long distances has not yet fully satisfied the ever-increasing demands of the communications industry. What is needed and what was not provided by the prior art is a cable that was made economically and that has operational performance levels that significantly exceed the criteria established by these standards for high-performance metal cables, such as TIA / EIA-568A. In particular, the sought-after cable must exhibit substantially high crosstalk margins and substantially high structural return loss margins (SRLs) to handle ever-increasing transmission rates, for example, 1.24 gigabytes per second. In fact, it is believed that the cable design of the present invention is capable of being used in a Gigabit Ethernet system without the need for special electronic devices.

BRIEF DESCRIPTION OF THE INVENTION The above problems have been overcome by a wiring arrangement of this invention which is capable of high speed transmission of the data streams at a relatively low level of crosstalk. A wiring means which is suitable for the transmission of data with relatively low crosstalk includes a first pair of metallic conductors, the pair including two insulated, plastic metal conductors which are twisted together. The medium also includes at least one other pair of metallic conductors, insulated each pair that includes two metallic conductors, insulated with plastic, which are twisted together and which are in a relatively close proximity to the first pair. The characterization of the twist is important and refers to the parameters such as the twist length as well as the length / arrangement of the core strand. More specifically, the particular combinations of the twist lengths and the length / arrangement of the core strand are purposely selected for each cable conductor pair in order to achieve performance capabilities that significantly exceed those required under TIA / EIA- 568A. In a particular embodiment of this invention, a cable comprises, as its transmission medium, four twisted pairs of individually insulated conductors with each of the insulated conductors including a metallic conductor and an insulating cover enclosing the metallic conductor. The joint twist of the insulated conductors of each pair is characterized as specifically set forth herein and the plurality of the transmission means are enclosed in a wrapping system which in the simplest mode may be a single liner made of a material of plastic. Additionally, the cable of the preferred embodiment includes a wrapping system that may or may not include a shield to link the protection of the cable against electromagnetic interference and prevent unwanted electromagnetic emissions or radiation from being generated by the cable. As a result of the particular twist scheme used for the insulated conductor pairs, the operational performance of the resulting cable is improved. Also, the cable of this invention is relatively easy to connect and is relatively easy to connect and install.

BRIEF DESCRIPTION OF THE DRAWINGS Other features of the present invention will be more readily understood from the following detailed description of the specific embodiments thereof when read in conjunction with the accompanying drawings, in which: Figures la and Ib are perspective view of two modes, one protected and one unprotected, of a cable of this invention to provide a substantially error-free data transmission over relatively long distances; Figure 2 is an elevation view of a construction for displaying a main unit computer, personal computers-and peripherals linked by the cable of this invention; Figure 3 is a schematic view of a pair of insulated conductors in an array for transmission in balanced mode; Figure 4 is a view of a data transmission system including the cable of this invention; Figure 5 is a cross-sectional view of two pairs and insulated conductors as they appear in a cable of this invention.

Figure 6 is a cross-sectional view of a pair of insulated conductors in an arrangement of the prior art; Y Figures 7a-7c graphically depict the relationship of certain operational performance criteria against the frequency for a cable that meets the existing standards and a cable of this invention.

DETAILED DESCRIPTION Referring now to Figures la and Ib, two modalities of a data transmission cable are shown which is designated generally by the number 20.

Specifically, the Figure represents an unprotected modality and Figure Ib represents a protected version of the present invention. While the difference between these two modalities resides in the wrapping system, it should be understood that the focus or main point of the invention is the particular arrangement of the transmission medium therein, which is the same for both modalities. Typically, the socket 20 can be used to network one or more computers 22-22 of main units, many personal computers 23-23, and peripheral equipment 24 on the same or different floors of a construction 26 (see Figure 2). The peripheral equipment 24 may include a high-speed printer, for example, in addition to any other known and equally suitable device. Desirably, the interconnection system minimizes system interference in order to provide a substantially error-free transmission. The cable 20 of this invention is directed to provide a substantially error-free data transmission in a balanced mode. More specifically, the particular cable design of the present invention simultaneously raises a series of operational performance criteria to levels that consistently exceed the current industry standards for high performance metal conductor cables. In general, a prior art transmission system, in balanced mode including a plurality of individually insulated conductor pairs 27-27 is shown in Figure 3. Each pair of insulated conductors 27-27 is connected from a source 29 of digital signals through a primary winding 30 of a transformer 31 to a secondary winding 32 which is connected to ground with a center tap. The conductors are connected to a winding 33 of a transformer 34 at the receiving end which is also connected to ground with a center tap. A winding 35 of the transformer 34 is connected to the receiver 36. With respect to the external interference, if it is from a power induction or from other radiated fields, the electric currents are canceled at the output end. For example, if the system must experience a pulse of electromagnetic interference, both conductors will be equally affected, resulting in an override, with no change in the received signal. For unbalanced transmission, a shield can minimize these currents but can not cancel them. To achieve transmission in balanced mode, it is necessary to connect additional components such as transformers in the circuit boards at the ends of the connection cable. Use in an unbalanced mode avoids the need for additional term equipment and returns to the cable compatible with the present equipment. However, due to the distances over which the cable of this invention is capable of transmitting data signals, substantially error-free at relatively high speeds, there may be a willingness to invest in the additional components at the ends of the cable that are required. for transmission in balanced mode. Additionally, there is a generally accepted requirement that the outer diameter of cable 20 does not exceed a predetermined value and that the flexibility of the cable must be such that it can be easily installed. The cable 20 has a relatively small outside diameter, i.e. in the range of about 0.1 inch to 0.5 inch, and is both strong and flexible, thereby overcoming the many problems encountered when using a cable with individually protected pairs. The resulting size of the cable depends on a variety of factors including the number of conductor pairs used as well as the type of the selected liner system. The particular cable of the preferred embodiment of the present invention cites the inclusion of four conductor pairs within the cable design. However, the cable 20 can, in fact, include between two and twenty-five pairs of insulated conductors. The particular advantages of the present invention over the prior art can be attributed to a specific length of twist and length / arrangement of the core strand used in the cable design described and claimed herein. As used herein, the kink length refers to the distance along the length of an insulated conductor pair for a complete revolution of the individual conductors around each other, and the length / arrangement of the core strand it refers to the distance along the length of the cable for the complete core or grouping of multiple conductor pairs to complete a complete revolution. With these definitions in mind, it is important to note that as used herein, the value for the twist length is the measure of the construction as a result of the twisting device used to create the conductive pairs and not as it skews upwardly. or down the length / arrangement of the cable strand with widely varying twist lengths, and lengths / arrangements of the core strand currently available, each of the currently sold designs are inferior to the cable of the present invention in at least some of the operational performance criteria, critical. Below is a table depicting the twist scheme used in the structural constitution of the cable according to the preferred embodiment of the present invention: In addition to the particular values of the twist length set forth above, the present invention combines these twist lengths with a length / twist arrangement value with a core strand length / arrangement value of between about 4 and 6 inches. in the same direction as the twists of the conductive pairs. More specifically, the preferred embodiment of the present invention incorporates a length / arrangement of the core strand of between about 4.6-4.9 inches in the same direction as the twist rotation of the conductor pairs. However, beyond the value realized from the construction of a cable according to the particular preferred embodiment of the present invention, as specifically quantified in the above manner, it should be understood that the present invention is also directed to cables designed using any common multiple of the values specifically quantified herein. In other words, while a particular set of quantified criteria for establishing a preferred twist scheme are presented above, it is further taught and claimed that significant improvement in operational performance can be achieved by constructing a cable with a circuit diagram. kink wherein the twist lengths and / or the length / arrangement of the core strand are multiple or common factors of any of the values within the ranges described as the preferred embodiment. For example, to select a value within each range of the twist lengths for the conductor pairs, and / or within the range for the length / arrangement of the core strand, and then multiply these values by a common number to establish a Twist scheme would also be considered to be within the scope of the present invention. As yet another structural aspect of the present invention that can be considered to further improve the operation of the resulting cable is the particular placement of the lead wires relative to one another. More specifically, in accordance with the preferred embodiment, the two twisted pairs with the shortest twist length should be placed diagonally between. yes. Therefore, while the essentials of this invention are directed to the selection of the most appropriate kink lengths and the length / arrangement of the thread, additional benefits can be recognized if the conductor pairs are optimally positioned relative to each other.

Referring now to Figure 4, an example system 40 is shown in which the cable 20 of this invention is useful. In Figure 4, a transmission device 37 at one extension is connected along a pair of conductors 42-42 and a cable to an interconnecting port 39 and then back along another cable to a receiving device 41. in another station. A plurality of the stations comprising the transmission devices 37-37 and the reception devices 41-41 are connected to the interconnection mouth 39 and then back along another cable to a receiving device 41 at another station. A plurality of the stations comprising the transmission devices 37-37 and the reception devices 41-41 can be connected to the interconnection mouth in what is referred to as a ring network. As can be seen in this example, the conductors are directed from the transmission device in one terminal to the mouth 39 and out to the receiving device in another terminal, thereby doubling the transmission distance. More particularly, the cable 20 of this invention includes a core 45 comprising a plurality of twisted pairs 43-43 of the individually insulated conductors 42-42 (see Figures la, Ib and 5) which are used for data transmission . Each of the insulated conductors 42-42 includes a metal portion 44 (see Figure 5) and an insulation cover 46. In a preferred embodiment, the insulation cover 46 can be made of any fluoropolymer material, such as TEFLON, or polyolefin material, such as polyethylene or polypropylene. Additionally, the outer skin 58 can be made of a plastic material such as polyvinyl chloride, by way of example. It should be noted that the present invention can be used in the design of either a protected or an unprotected cable. In particular, the Figure illustrates an unprotected cable design while Figure Ib represents a protected cable design. The difference between the two designs resides only in the wrapping system selected for the given application and is not seen to be the essence of the present invention. However, for integrity, both protected and unprotected modes are set forth herein. In a protected embodiment, the core 45 is enclosed in a wrapping system 50 (see Figure Ib). The wrapping system may include a core winding 51 and an inner liner 52 comprising a material having a relatively low dielectric constant. In a preferred embodiment, the material is polyvinyl chloride (PVC). In addition, the thickness of the inner liner is equal to the product of approximately 0.167 to 1.0 times the outside diameter (DOD) of an insulated conductor 42. For example, if the DOD of the insulated conductor was 0.036, the thickness of the inner liner would be approximately 0.006. up to approximately 0.036. The inner liner 52 is enclosed in a laminated product 53 (see Figure Ib) comprising a metal shield 54 and a plastic film 55 and having a longitudinally extending, overlapping seam 56. The laminated product is arranged so that the plastic film faces outward. In a preferred embodiment, the thickness of the metal shield 54, which is typically made of aluminum, is 0.001 inches while the thickness of the film is 0.002 inches. A drainage wire 59, which may be a strand or solid wire, is placed between the shield 54 and the inner liner 52. The metal shield 54 is enclosed in an outer skin 58 which comprises a plastic material such as polyvinyl chloride , as an example. In a preferred embodiment, the thickness of the outer skin 58 is approximately 0.020 inches. The two embodiments described above, protected and unprotected, are believed to be the most common form of cabling means for employing the present invention. However, other forms of communication transmission may be within the scope of the present invention. For example, the plurality of pairs can be placed side by side in a wiring channel and not enclosed in a plastic liner as yet another embodiment of the present invention. Additionally, the materials for the insulation of the conductors and / or the liner (s) may be such as to return the flame retardant cable and smoke suppressor. For example, these materials can be fluoropolymers. The Underwriters Laboratories have implemented a test standard to classify communication cables based on their ability to withstand exposure to heat, such as from a building fire. Specifically, the cables can be classified either as ascending or distribution. Currently, the UL 910 flame test is the standard to which the cables are subjected before receiving a distribution classification. It is proposed that the preferred embodiment of the present invention use materials for the lining and / or insulation of the conductor such that the cable qualifies for a distribution classification. To achieve this distribution classification, any number of known technologies can be incorporated into a cable that exhibits the other specific attributes requested and claimed herein. Even given the preference given above, it should be understood that a cable made in accordance with the present invention does not require this attention, or benefits of the selected lining and insulation material. In fact, other particular test standards may be applied and used to qualify the cables incorporating the attributes of the present invention depending on the specific environment in which the cable is to be placed. The pairs of insulated conductors 42-42 are adjacent to one another in a cable or a wiring channel, by way of example. In the present, the pairs are in close proximity to each other and protection against crosstalk must be provided. The characterization of the twist of the conductors of each pair is important for the cable of this invention to provide a substantially error-free transmission at relatively high bit rates. The twists of the pairs and the separation of the pairs, which is the distance between the conductor pairs, are the main parameters that are going to be controlled. Therefore, it becomes necessary to measure the separation of the pairs and the separation of the twist. Usually, twist pairs have been specified by twist lengths of conductor pairs and twist separation by the difference in twist lengths. Notably, a cable design, particularly described in the commonly assigned US Patent No. 4,873,393 referred to above, proposes that the twist length for each conductive pair should not exceed the product of approximately 40 and the outer diameter of the insulation of one of the drivers of the pair. According to the '393 patent, for substantially error-free data transmission, at high speed, the conducting pairs that are in close physical proximity must be separated well in the characteristic twist as measured by the twisting frequency of each pair . As a matter of example and definition, a twist length of 0.5 inches is equal to a twisting frequency of two twists per inch or 24 twists per foot; a twist length of 2 inches is equal to a kink frequency of 0.5 kinks per inch or 6 kinks per foot; and a twist length of 5 inches is equal to a twist rate of 0.2 kinks per inch or 2.4 kinks per foot. in other words, 12 divided by the twist length (in inch) is equal to the twist number per foot denoting a twist frequency value. As described in the North American Patent No. 4,058,669 which was issued in the names of W. G.

Nutt and G.H. Webster and expressly incorporated herein by reference, using the twist frequency spacing as a design guide, provides a closed or staggered separation of the high twist frequencies, but advantageously, a wide separation of the low frequencies of twists. However, different from each of the cable designs referred to above, where the twist frequency characteristic is a critical interest, the present invention provides a unique cable design whose structural parameters are not only exposed more clearly but as noted previously, it consistently produces a cable that reliably exceeds a number of operational design criteria currently used to quantify and measure high-performance metal cables. Twist distortion must be considered and must be reduced to reduce crosstalk. Ideally, a conductive pair that has four kinks per foot would forever be a perfect helix that has four turns per foot, and, if the electromagnetic change was perceived along this pair, a sine wave would be detected that has four cycles per foot. But when the conductive pairs that have usual kink lengths are mounted in a core, one pair distorts the other. For example, if a conductive pair with three kinks per foot that is adjacent to one with four kinks per foot is examined, the spectral components associated with the four kinks per foot are observed, and to the extent that they exist, crosstalk occurs as if the adjacent walls had both four kinks per foot. The relatively short kinks of this invention resist this type of distortion.

The invasion of the pair is also an important consideration. The plurality of conductive pairs in the cable of this invention requires more space in the cross section than cables made in the past for the use of exchange in telephone communications. In some existing prior art, it was apparently more desirable to have these adjacent pairs coupled together to increase the density or the number of pairs in as small an area as possible. Relatively short twist lengths and the method by which the plurality of conductive pairs are brought together to form the core 45 minimizes the chance of an insulated conductor of a pair to physically latch or rest on an insulated conductor of an adjacent pair. In order to understand the packing parameter and its effect on crosstalk, attention is now directed in Figures 5 and 6 in each of which a schematic view of two pairs of insulated conductors is shown. The conductors in Figure 5 have already been referred to hereinbefore and are designated by the numerals 42-42, while the conductors shown in Figure 6 represent an arrangement of the prior art and are designated 60-60.

The conductors of each pair have a center-to-center separation of a distance "a" and the centers of the pairs separated by a distance "d" equal to twice the distance "a". The crosstalk between the pairs is proportional to the amount a2 / d2. Therefore, the greater the distance n "between the centers of the conductive pairs, the smaller the crosstalk will be, as can be seen in Figure 6, which represents some prior art pairs of wires, it is common in cores packed for at least one conductor 60 individually isolated from one pair invades the space of another pair as defined by the circumscription circle 64. On the other hand, comparing Figure 5 in which neither the isolated conductor 42 of a pair invades the circumscribed space in The other pair's circle On average, along the length of the conductive pairs associated together in the cable 20, the centers of the pairs will be separated by the distance "d." This results in reduced crosstalk. short and the method of bringing together the conductive pairs effectively reduces the coupling of the pairs and causes each conductor pair to behave as if it were placed in, and remain in a cylinder that has a diameter of twice the outer diameter of an insulated conductor. Although the cable pairs have shared space with respect to the relation of the electromagnetic fields there is little, if any, compartment of the physical spaces defined by the circumscription circles. As a result, the transmission loss between the pairs is kept at a low level and the crosstalk between the pairs is acceptable. The absence of the individual protection or shield of the pair overcomes another objection to the prior art cables. The outer diameter of the insulation cover 46 around each metallic conductor is sufficiently small so that the insulated conductor can be determined with the physical equipment of the normal connector. The cable of this invention is also advantageous from the point of view of the number of colors required to identify the insulated conductors. In general, with the longer twist lengths, when the wrapping system is removed from a terminal portion of a wire, the twisted pair conductors are intermixed. For example, a white isolated conductor of a blue-white pair can be mixed with a green isolated conductor of a green-white pair. As a result, a greater number of color combinations should be used and therefore inventory should be made to ensure that proper identification can be made in the removal of a portion of the wrapping system. Longer twist pairs undergo unlocking at splices that can result in a type of splice error called split pairs in which a wire from one pair is confused with one from another pair and two pairs become so useless On the other hand, with the cable of this invention, the short twist lengths cause the twist to remain even after the wrapping system is removed.

• As a result, the number of colors that need to be used is significantly reduced. Additionally, due to the fact that the individual drivers of the firm pairs are less likely to separate, there will be significantly fewer errors of the connectors that occur during the use of these cables. The operational performance of the present invention is now more specifically addressed compared to accepted industry standards for high-performance metal cables, attention is drawn to Figures 7a-7c. Each of these figures graphically shows how the cables manufactured in accordance with the present invention were tested in relation to the values currently used to qualify the cables of category 5 under TIA / EIA-568A. In particular, Figure 7a illustrates the relative values of crosstalk, specifically near-end crosstalk (NEXT), Figure 7b illustrates the relative values of power sum-of-crosstalk (PSUM NEXT), while Figure 7c illustrates the Relative values of the structural return loss (SRL). Each of the operational performance values, specifically NEXT, NEXT PSUM and SRL are measured in dB as they vary with the frequency shown as the logarithmic MHz scale. While the specific values of the operational performance represented adequately show the capability of the present invention to Exceeding the currently governing standards, it should be noted that the calculations are based on very conservative test results that would ensure a cable with operational capabilities that can be reproduced reliably and consistently even in view of the inherent manufacturing and measurement tolerances that exist. In addition, as a matter of priority, it is to be understood that as shown herein, the bottom or bottom baseline represents the present values as defined by the standard identified above, while the upper or uppermost line represents a more conservative measure of the performance of a cable manufactured in accordance with the present invention. Figure 7a shows that over the frequency range of about 0.75 MHz to about 500 MHz, the more conservative calculations of the processor cables according to the present invention exceed the existing standards for near-end crosstalk (NEXT) by at least 10 dB. Also, Figure 7b represents that over a similar frequency range, the conservative calculations and measurements of the cables as claimed herein after at least an 8 dB improvement over the normal values with respect to power sum-of-power crosstalk. (PSUM NEXT). Finally, Figure 7c documents at least a 3 dB improvement over the normal levels present for structural return loss (SRL) up to 100 MHz, which is where the present normal values stop, although the SRL values of this invention are projected to approximately 500 MHz. However, even beyond the particular values identified above represented in the associated Figures, it is anticipated that the cable design of the present invention can typically produce a cable that exceeds the standards of the standards by at least approximately 15 dB for the NEXT, pro at least approximately 13 dB for the NEXT PSUM and by at least approximately 7.5 dB for the SRL. In addition to the specific twist scheme factors discussed above, a number of different factors must also be considered in order to arrive at a cable design that can be easily sold for these uses. The lining of the resulting cable must exhibit low friction to improve cable pull in conduits or on supports. Also, the cable must be strong, flexible and resistant to crushing, and must be conveniently packed and not unduly heavy. Because the cable can be used in busy construction spaces, the property of retardation to the flame is also important. The data transmission cable must be inexpensive. It must be able to be installed in an economical way and be efficient in terms of the space required. It is not uncommon for the installation costs of the cables under construction, which are used for interconnection, to oppress the costs of the cable material. Construction cables should have a relatively small cross section considering small cables not only to improve installation but to hide easier, require less spaces in conduits and channels and wiring closets that reduce the size of the associated connector hardware. The cable connection capacity is very important and is more easily achieved with the pairs of insulated, twisted conductors than with any other means. A widely used connector for insulated conductors is one that is referred to as a split-beam connector. Desirably, the outer diameter of the insulated conductors of the sought-after cable is efficiently small so that conductors can be terminated with these existing connector systems. Additionally, any proposed arrangement as a solution to the problem must be one that does not occupy an undue amount of space and one that facilitates a simple connection arrangement. There is a need to provide cables that can transmit data rates of up to gigabit per second, error free, from stations to cabinets or between computer furniture separated by distances comparable to main rooms, easily installed, easily adaptable to the architectures of construction, and be safe and durable. It should be understood that the arrangements described above are merely illustrative of the invention. Other arrangements may be envisioned by those skilled in the art which will incorporate the principles of the invention and fall within the scope and spirit of the invention.

It is noted that in relation to this date, the best method known by the applicant to carry out the present invention, is the conventional one for the manufacture of the objects to which it refers. Having described the invention as above, the content of the following is claimed as property:

Claims (21)

1. A cabling means, characterized in that it comprises: a plurality of pairs of conductors, each of the pairs including two insulated metal conductors that are twisted together according to a twist scheme selected from the group consisting of 1) a pair having a twist length of about 0.43 and about 0.45 inches, a pair having a twist length between about 0.40 and about 0.42 inches; a pair having a twist length between about 0.58 and about 0.61 inches; and a pair having a twist length between about 0.65 and about 0.69 inches; and 2) at least four pairs having individual twist lengths, equal to a multiple / common factor of values within the specific ranges listed immediately above; and a liner enclosing the plurality of pairs of metallic conductors.

2. The wiring means according to claim 1, characterized in that it also has a length / arrangement of the core strand of between about 4 and 6 inches.

3. The cabling means according to claim 2, characterized in that the length / arrangement of the core strand is approximately 4.6-4.9 inches.

. The wiring means according to claim 1, characterized in that there are four pairs of metallic conductors.

5. The cabling means according to claim 4, characterized in that the two twisted pairs with the shorter lengths of twists are placed diagonally to each other.

6. The wiring means according to claim 1, characterized in that the metallic conductors are 24 AWG.

7. The wiring means according to claim 1, characterized in that the lining is made of a material with flame retardant and smoke suppressing properties.

8. The cabling means according to claim 1, characterized in that the insulation of the metallic conductors is made of a material with flame-retardant and smoke-suppressing properties.

9. The wiring means according to claim 1, characterized in that the flame retardant and smoke suppressive properties of the materials used for the lining and the insulation of the conductors are sufficient to allow the cable to pass the criteria of the test to the flame UL910.

10. A wiring means, characterized in that it comprises: a plurality of conductors, each of the pairs including two isolated metallic conductors that are twisted together according to a twist scheme selected from the group consisting of 1) a pair that It has approximately 17 and 19 sprains per foot; a pair that has between approximately 19 and 21 kinks per foot; a pair that has between approximately 27 and 28 sprains per foot; a pair that has between approximately 29 and 30 sprains per foot; and 2) at least four pairs having individual twist values per foot equal to a multiple / common factor or values within the specific ranges listed immediately above; and a liner enclosing the plurality of pairs of metal conductors, isolated.

11. A wiring means according to claim 10, characterized in that it has a core strand length / arrangement of between about 4 and 6 inches.

12. The cabling means according to claim 11, characterized in that the core strand length / arrangement is approximately 4.6-4.9 inches.

13. The wiring means according to claim 10, characterized in that there are four pairs of metallic conductors.

14. The wiring means according to claim 13, characterized in that the two twisted pairs with the shortest twist length are placed diagonally with each other.

15. The wiring means according to claim 10, characterized in that the size of the metallic conductors is 24 AWG.

16. The wiring means according to claim 10, characterized in that the lining is made of a material with flame retardant and smoke suppressing properties.

17. The wiring means according to claim 10, characterized in that the insulator of the metallic conductors are made of a material with flame retardant and smoke suppressing properties.

18. The wiring means according to claim 10, characterized in that the flame-retardant and smoke-suppressing properties of the materials used for the lining and the insulation of the conductors are sufficient to allow the cable to pass the criteria of the test to the flame UL910.

19. A carrier of communication signals, characterized in that it comprises: a plurality of conductors, each of the pairs including two isolated metallic conductors that are twisted together according to a twist scheme selected from the group consisting of 1) a pair which has between 17 and 19 sprains per foot; a pair that has between approximately 19 and 21 kinks per foot; a pair that has between approximately 27 and 28 sprains per foot; and a pair that has between approximately 29 and 30 sprains per foot; and 2) at least four pairs having individual values of twist per foot equal to a manifold / common factor with values within the specific ranges listed immediately above; and a channel that supports the plurality of pairs of isolated metallic connectors.

20. A communication signal carrier according to claim 19, characterized in that it also has a core thread length / exposure of approximately 4.6-4.9 inches.

21. A local area network, characterized in that it comprises: at least a first and a second communication devices connected together such that the communication signals can be transported between these devices by a plurality of pairs of conductors, each of the pairs including two insulated metal conductors twisting together according to a twist selected from the group consisting of 1) a pair having between about 17 and 19 twists per foot; a pair that has between approximately 19 and 21 kinks per foot; a pair that has between approximately 27 and 28 sprains per foot; and a pair that has between approximately 29 and 30 sprains per foot; and 2) at least four pairs having individual values of twist per foot equal to a multiple / common factor of values with the specific ranges listed immediately above. SUMMARY OF THE INVENTION A cabling means is described which is suitable for data transmission with relatively low crosstalk including a plurality of metallic conductor pairs, each pair including 2 insulated plastic metal conductors which are twisted together. The characterization of the twist is important and relates the parameters such as length of twist length / arrangement of the core strand. More specifically, particular combinations of twist lengths and length / arrangement of the core strand are purposely selected for each isolated pair of the cable in order to achieve the performance capabilities that significantly exceed those required under TIA / EIA-568A. In a particular embodiment of this invention, a cable comprises, as its transmission medium, four twisted pairs of individually insulated conductors with each of the insulated conductors including a metallic conductor and an insulating cover enclosing the metallic conductor. The joint twist of the insulated conductors of each pair is characterized as specifically set forth herein and the plurality of the transmission means are enclosed in a wrapping system which in the simplest mode may be a single liner made of a material of plastic. As a result of the particular twist scheme used for the insulated conductor pairs, the operational performance of the resulting cable is improved. Also, the cable of this invention is relatively easy to connect and is relatively easy to connect and install.