Browse Prior Art Database

Synchronization of a Fiber-Optic Star Coupled Network

IP.com Disclosure Number: IPCOM000101763D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 4 page(s) / 144K

Publishing Venue

IBM

Related People

Dimmick, RF: AUTHOR

Abstract

Disclosed is a method for bit and byte synchronization on a high performance half duplex multiported fiber-optic network. This is a method by which any string of intelligible data in the form of bits is wrapped back to the source of the data for verification, with a delay equal to the transmission time of the media. The delay in the data path is maintained equal to the delay in the synchronization path by means of the structure of the transmission media. The verification logic is not part of this disclosure, but is familiar to those skilled in the art.

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Synchronization of a Fiber-Optic Star Coupled Network

       Disclosed is a method for bit and byte synchronization on
a high performance half duplex multiported fiber-optic network.  This
is a method by which any string of intelligible data in the form of
bits is wrapped back to the source of the data for verification, with
a delay equal to the transmission time of the media.  The delay in
the data path is maintained equal to the delay in the synchronization
path by means of the structure of the transmission media. The
verification logic is not part of this disclosure, but is familiar to
those skilled in the art.

      Figs. 1a and 1b illustrate the method and logical components
necessary to perform bit and byte synchronization between two ports
of a star coupled fiber-optic network. The star coupler illustrated
shows potential for up to 8 ports, but the concept will work for any
number of ports over any distance which can be accommodated within
the loss budget of the optical drivers and receivers.  The bit and
byte synchronization concepts work equally well for a point-to-point
connection without the star coupler, in which case arbitration is
simplified.

      The star coupler is a multiport optical divider of energy.  The
energy supplied to any single input port is divided equally among
each of the output ports, one of which echoes the input back to the
transmitting node.  The star coupler ports are connected to the
transmitters and receivers of the network nodes by means of
fiber-optic cables.  This disclosure requires that two star couplers
be used, each with an equal number of input and output ports.  Star
coupler 0 is used for the data path, and star coupler 1 is used for
the transmission of the clock which caused the data to be shifted
onto the data path.  Each node is connected to the two star couplers
by means of a four fiber-bundled cable. Two of the fibers in the
bundled cable comprise the data path, one each for transmission and
reception of the data. The other two fibers are used for the
synchronization path (clock), one each for transmission and reception
of the clock. It is assumed that the transmission delays in the
cables for both the data paths and clock paths are essentially equal
since the media lengths are equal within an inch.  It is also assumed
that the delays in the two star couplers for identical input and
output ports are equal within a few (less than 2) nanosecon...