Page 40 - The TM Submarine Cable Book

4: The Connectors

Branching Unit  Converting the optically carried signals
to electrical signals, using an add-drop
multiplexer to divide and recombine the
signals on the desired paths, the
reconverting back to optically carried
signals. This signal conversion and
multiplexing equipment will require
power.

 Using a reconfigurable optical add-
drop multiplexer to direct optical carrier
frequencies down desired paths. The
power requirements of optical
multiplexing in this manner will be lower
than the previous method.

In both types of cable system, more than
one technique can be used
A submarine branching unit simultaneously.
allow the cable to split to serve
more than one destination that is
one branch might head for a cable
landing point and others may
continue to a length distance of
another landing station.
There are several methods by
which the split can be affected,
which can also depend on the type
of cable system:

Purely electrical systems (now
almost obsolete) can be split by
either:

 Physically separating the
signal cables so some go in one
direction and some in another, The conventional symbol used for a
which requires no additional submarine branching unit in maps of cable
power. routes is a small equilateral triangle with
 Using an add-drop (usually) one vertex pointing towards the
multiplexer to direct the signals top of the map.
down one path or the other. The
electrical equipment that acts as
the add-drop multiplexer will need Optical Fibre basic
powering.
structure
• Optical fibre cable systems
can be split by either:

 Physically separating the
signal-carrying fibres so some go The core performs the function of
in one direction and some in transmitting the light waves, while the
another, this requires no additional cladding is to minimize surface losses and
power. to guide the light waves.

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