Submarine Line Terminating Equipment (SLTE)
SubCom’s terminal equipment makes it possible to transmit and
receive multiple high-quality, high-bandwidth signals over ultra-long distances. The
multiplexed optical signals generated by the equipment are ideally suited for ultralong-
haul transoceanic transmission but are also suitable for shorter-distance interisland
or coastal applications.
The four main components of the SLTE are:
- High Performance Optical Equipment (HPOE) — Provides special grooming of
the optical line signal to enable transmission at data rates of 10 gigabits per second
(10 Gbps) over distances in excess of 12,000 km without regeneration. Some of the
HPOE features are:
- Very powerful forward error correction (FEC)
- Extremely precise power- and wavelength-adjustable transmitting laser
- Automatic transmit and receive self-adjustment (including wavelength preemphasis)
for optimum transmission performance
- Wavelength Termination Equipment (WTE) — Provides the Wavelength Division
Multiplexing (WDM) and Wavelength Division Demultiplexing (WDD) functions,
including terminal dispersion compensation per wavelength or group of
wavelengths. The WTE allows up to 136 wavelengths to be combined on a single
- Terminal Line Amplifier (TLAs) — Provides amplification of the transmitted and
received optical signal. Redundant laser pumps provide robust, trouble-free
- Initial Loading Equipment (ILE) — These optical-density generators populate the
optical spectrum to obtain the designed end-to-end performance from Day 1. The
ILE allows a system to grow according to plan over time as bandwidth requirements
increase, ensuring that the undersea plant will function optimally even when the
system is not built-out to its maximum design capacity
Line Monitoring System (LMS)
The optical line monitoring system enables tracking of the function and performance
of the undersea plant.
The LMS consists of the LME (Line Monitoring Equipment) circuit pack, high-loss
loopback components in the repeaters and terminals, access couplers, and LMS
software. Performance of the entire undersea plant can be monitored using both in-service
and out-of-service measurements.
The LMS in-service measurements act as an early-warning system, automatically
alerting owners to changes that could affect operation. Out-of-service LMS OTDR
measurements allow fiber faults to be localized accurately, with a resolution as tight as
500 meters, without the need to purchase additional test equipment.
Power Feed Equipment (PFE)
Powering the undersea repeaters from shore, SubCom PFEs can
provide up to 12,500 volts at currents up to 1.6 amperes, sufficient to power a cable
across the Pacific Ocean from a single station. A fully redundant design aims for
virtually zero network down time.
Different PFE sizes accommodate all variants of undersea networks, whether
transoceanic, inter-island, or coastal.
Element Management System (EMS)
The SubCom Element Management System (TEMS) can be
thought of as the control panel for a submarine cable system. TEMS acts as the
user’s main interface for all of the undersea and dry equipment, providing network element
management for the LTE, LME, and PFE and allowing users to monitor the
performance of and localize faults in their systems. SubCom’s network
management system, TEMS-NMS, extends the TEMS monitoring and management
functionality to the entire network.
Terrestrial Network Interface Equipment
SubCom’s undersea system solutions accommodate a variety of
terrestrial network equipment. Through strategic procurement relationships with a
variety of suppliers, SubCom can customize network architectures
based on individual customer needs. The SLTE offers multiple access interfaces (STM-
64 SR, IR, 10 G GigE, 4xSTM -16, 1xN protected, etc) that support the various terrestrial
network equipment elements including routers, ATM switches, SDH multiplexers/cross
connectors, and terrestrial transponders.
SubCom also offers complete equipment integration and testing
capabilities in the system test laboratory at our R&D facility in Eatontown, New Jersey.
Fiber Optic Undersea Cable
SubCom manufactures several families of cable for undersea cable
systems. The cable is designed to protect the optical fiber from the harsh undersea
environment for 25 years, and also deliver power for the undersea amplifiers and
The cables have different core diameters to provide protection for different numbers
of fiber pairs — from a single pair to up to twelve pairs for ultrahigh-capacity systems.
Each of these cable families includes a broad spectrum of cable protection designs,
ranging from lightly protected deep-water cable to double-armored cable for use in
shallow water where resistance to crushing and extreme abrasion is required. A careful
study of the ocean bottom conditions on the cable route will determine what cable
types must be used for best performance.
The SubCom repeater amplifies the optical signal so that it can be
transmitted over long distances. SubCom’s 980-nanometer undersea
repeaters use state-of-the-art Erbium-doped optical amplifier technology to achieve
high performance and high reliability to transmit multiple-wavelength signals on the
fiber pairs over transoceanic distances. The company’s current repeater designs can
accommodate one to eight optical amplifier pairs.
Undersea Branching Units (BU)
A branching unit allows a single trunk cable to be split into two branches so it can feed
multiple landing points. Four main branching-unit types are available for different
applications. The most basic is the passive branching unit, which allows the fibers in a
single trunk cable to be routed over two different paths.
More advanced is the optical add-drop multiplexer (OADM) branching unit, which
not only splits fibers but allows some wavelengths in a trunk fiber to be routed over
one path, while sending the others down a second path. OADM is an attractive
option for undersea networks with branched architecture. An OADM branching unit
allows system operators new levels of flexibility in capacity management by allowing
“sharing” on a single fiber pair (FP) among multiple point-to-point connections in a
trunk-and-branch undersea network. This capability improves the cost effectiveness of
bandwidth delivery, especially to landing points with modest capacity requirements,
and offers significant advantages in terms of network configurations and traffic
The other two main branching unit types add power-switching capability, allowing the
power configuration of the undersea plant to be changed to accommodate safe repair
and recovery operations while minimizing the impact on traffic.