Browse Prior Art Database

Printed Circuit Board Crosstalk Reduction on the Token Ring Network

IP.com Disclosure Number: IPCOM000114236D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 2 page(s) / 97K

Publishing Venue

IBM

Related People

Creigh, JL: AUTHOR [+5]

Abstract

Disclosed is a method of reducing crosstalk caused by RJ-45 connectors on Shielded Twisted Pair (STP) Token Ring Networks.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 55% of the total text.

Printed Circuit Board Crosstalk Reduction on the Token Ring Network

      Disclosed is a method of reducing crosstalk caused by RJ-45
connectors on Shielded Twisted Pair (STP) Token Ring Networks.

      STP is high quality, low crosstalk (-50dB) cable that is used
in Token Ring networks where long drive distances (greater than 400m
at 16MB/s) are required.  The standard connector for Token Ring
networks has been a 9 pin D-Shell which has low crosstalk (-60dB).  A
RJ-45 connector is a less expensive connector than a 9 pin D-shell
and is used in Unshielded Twisted Pair (UTP) networks.  UTP cable can
have high crosstalk (-26dB).  UTP has a large installed base as this
is also been used for the telephone system.

      The major drawback of using an RJ-45 connector in a STP system
is that the crosstalk of the RJ-45 connector (-40dB) is several times
greater than the crosstalk of the STP cable.  The higher crosstalk of
the RJ-45 connector limits the drive distance of STP systems.

      The main cause of crosstalk in the RJ-45 connector is
capacitive coupling of the transmit to receive lines in the connector
itself (Figs. 1 and 3).  The coupling is caused by long parallel runs
of the signal lines that have to fit the form of the connector.  The
signal lines in the connector are large to provide mechanical
strength when the cable with the modular plug is inserted.  The total
signal distance (both horizontal and vertical) and the large size of
the lines ma...