At&t Bell Laboratories

Lucent Technologies Inc.

At&t Technologies, Inc.

At&t Technologies Inc., At&t Bell Laboratories

Richard D Beggs

Harold Wayne Friesen

Wendell G Nutt

David R Hawkins

Stephen Taylor Zerbs

David M Mitchell

Palmer D Thomas

Daryle Pat Donner

Luc W Adriaenssens

An electrical cable is disclosed in which at least two pairs of insulated conductors are bound by a substantially circular jacket. The conductors in one of the pairs are twisted or rotated about one another in a spiral pattern at a frequency corresponding to a first twist lay or length. The conductors in a second pair are also twisted about one another at a frequency corresponding to a second twist lay. Finally, the two pairs of conductors are stranded about one another at a frequency corresponding to a strand lay. The substantially circular jacket resists the tendency to jam cable processing machines (e.g., a connectorization machine) when being dispensed from a pay-off reel, which is a common problem in prior art patch cord designs. As a result, the cable reduces manufacturing costs. In addition, the cable provides improved electrical performance, as measured by several performance standards, over prior art cable designs.

High speed transmission patch cord cable

A fire-resistant cable (20) which is suitable for the transmission of high frequency signals in a local area network includes a core which comprises a plurality of twisted pairs (22,22) of insulated conductors (24,24) and a jacket (35). Each insulated conductor of each pair includes an elongated metallic member (26) and an insulation system (28). The insulation system which is characterized by a suitable low dissipation factor includes dual layers, an outer one of which includes a flame-retardant plastic material. Also, the insulation system is characterized by a suitably low dielectric constant and by compatibility with a relatively short pair twist scheme. In one embodiment, the insulation system includes an inner layer (30) of a polyolefin plastic material and an outer layer (32) of a flame-retardant polyolefin plastic material. The jacket comprises a plastic material characterized by a suitably low dissipation factor and dielectric constant and in a preferred embodiment comprises a flame-retardant polyolefin plastic material. Preferably, the twist length of each pair does not exceed the product of about forty and the outer diameter of an insulated conductor of each pair.

Fire-resistant cable for transmitting high frequency signals

A cable (20) which is particularly suited to the transmission of substantially error-free data at relatively high rates over relatively long distances includes at least two pairs of individually insulated conductors (42--43). Each pair of individually insulated conductors is enclosed individually in its own tubular member (51) comprising a plastic material. A metallic shield (60) encloses the tubular members, and in a preferred embodiment, a plastic jacket (80) encloses the shield. In the preferred embodiment, two pairs of voice communications conductors are disposed at opposed locations between the shield and the jacket. The thickness of the tubular member is such that each insulated conductor of each twisted pair is caused to be spaced from the shield a distance which is not less than one half the diameter of the metallic wire portion of each pair enclosed by the tubular member.

Local area network cable

A parallel data transmission system (20) comprises a cable (40) which is capable of balanced mode transmission but which is driven in an unbalanced mode. The cable includes a plurality of twisted pairs of individually insulated conductors (42--42) enclosed by a metallic shield (54). The twist lengths are relatively short to cause the pairs to be decoupled sufficiently from one another to allow substantially error-free, parallel transmission over relatively long distances. Interposed between the core and the shield is a spacing member (52) which has a relatively low dielectric constant. Receiving facilities are provided for detecting whether the level of transmitted signals is above or below predetermined threshold values and for converting the received signals into one of two or more logic levels. Advantageously, this system increases substantially the distances over which substantially error-free transmission in an unbalanced mode can be accomplished.

Data transmission system

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Buford, GA, United States of America

Richard D Beggs