1. Submarine Cable System Functions & Repair

2. IP Cloud

3. World Submarine NW Map

4. DWDM
WDM (Wavelength Division Multiplexing), it uses different wavelengths on the same fibre & is totally protocol independent (SDH, ATM, Ethernet…)
It is known as Dense Wavelength Division Multiplex (DWDM) when the wavelengths are close (a few nm.)
For a DWDM Transmission system, 40/80 or at present 160 or more wavelengths in Optical C-Band (1530nm to 1565nm wavelength spectrum) can be carried on one fibre.

5. Why DWDM a) Overcome fiber exhaust / lack of fiber availability
problems (better utilization of available fiber)
d) Cost effective transmission
e) No O-E-O conversion delays
f) Wave length leasing instead of Bandwidth leasing
b) Space and Power savings at intermediate stations
c) Easier capacity expansion

6. Evolution of Submarine Transmission Technology
SDH & DWDM combined
SDH and DWDM are complementary.
SDH provides:
flexibility
resilience in case of failure
DWDM provides:
very high bandwidth
So For higher bandwidth transmission over a longer distance on the International network across continents/countries, SDH & DWDM combinely evolves to Submarine Transmission network

7. Submarine Fiber Optic Network system
SLTE, PFE, LME,
NMS and DCN
Fully integrated Undersea System
Using with -
Cables
Repeaters
Branching Units
Terminal Equipment

8. What makes a Submarine Cable Network
Terminal Equipment
Power Feeding
Equipment
Cable
Branching unit
Repeater
Cable
station
Network Management

9. Undersea Cables

10. Double Armoured Cable – For Deep & Rocky Seabed for double protection

11. Functions of Submarine Network

12. Functions & Terminologies

13. Submarine Wetplant & components
Wet plant comprises the following equipment/components:
Undersea Cable
Land Cable
Optical Fiber
Cable joints
Undersea Repeaters
Gain equalizers
Branching Units

14. Major Components of Submarine system
SLTE &
Wetplant
NMS
NMS
Cable Station
SL-17 Undersea Cable
CTE
Full Fiber Drop Branching Unit
Beach
TRPDR l 1
Joint
RL Cable
WTE
HV Power +
N Channels
TRPDR l 2
TLA
HV Shield
TRPDR l 3
ADM
Undersea Repeater
STM-16/ STM-64 Ÿ
PLINB Ÿ Ÿ
Ground
TRPDR l n
Ocean
LTE #1
Ground
TRPDR l 1
OGPP
PFE
N Channels
TRPDR l 2
TRPDR
Transponder HV
: High Voltage
LME
: Line Monitoring Equipment
OGPP
: Ocean Ground Protection Panel
PFE
: Power Feed Equipment RL
: Rodent Lightning
TLA
: Terminal Line Amplifier
WTE
: Wavelength Termination Equipment
ADM
TRPDR l 3 Ÿ
Building Ÿ
Ground
STM-16/ STM-64 Ÿ
COTDR
LME
TRPDR l n
LTE #2

15. Submarine Transmission Line Terminating Equipment1
TRPDR 2
N-1 N
WTE l1 l2
lN-1 lN
Note: Any module of the LTE may not be included depending on the specific
requirements of the system (distance, bit rate, SDH or SONET equipment, etc.)
10 Gbps (S-64.2) Interface IP
OXC
ADM
ATM
Line Amp
Submarine Cable
One Fiber-Pair
N x 10Gbps
(optional) ILE
Line Monitoring Wavelengths
(only for repeatered systems)

16. UnderSea Repeaters Repeaters use state-of-the-art optical amplifier
technology to achieve high performance and
reliability in the transmission of multiple
wavelength channel signals on multiple fiber
pairs which normally use 980nm Pump for
boosting up optical signal

17. Inside Repeater & different types
1/2/3/4 up-to 8 Amplifier pairs per Repeater
Low/High Gain Repeaters.
Low noise & Wide BW Repeaters
980 nm Pumps used in Repeaters.

18. Gain Equalisers
Gain Equalizer function is needed for every 5-10 spans depending on the total length of system. It is required because of non-flat nature of EDFA amplifier to compensate the gain which results with wider range of wavelength for traffic.

19. Branching Unit
Branching units (BUs) are designed for use in systems having three or more landing sites. Optical signals are routed among the three cables that connect to the BUs.
There are different types of BU’s. These BU can be controlled for electrical connections relay from the landing station SLTE equipment using commands on the same Optical channel.

20. Types of BU
Passive BU – The Electrical connections/branches can’t be switched or controlled from Station & it is electrically passive & doesn’t consume any electrical power. Also it is optically passive, means no Adding/Dropping of Wavelengths among three legs.
Power Switched BU – This type BU provides controllable electrical connections among the three cable legs, as well as to the sea-ground electrode built into the trunk leg cable termination. The electrical connectivity within the 34A-Type BU is controlled
on a powered system by means of an optical command
signal & it will have a command receiver.
Power Switched OADM BU – It is similar to Power
switched BU, but having optical add/drop functionality
using a OADM inside the BU, which makes
it optically & electrically controllable among three legs.
Non-power switched BU – It is similar to Passive BU, but having OADM functionality.

21. PFE
Under Sea Repeaters requires power for operation of Electronics circuit & the Power Feed Equipment (PFE) provides power to the these repeaters & Power switched BU.
These PFEs supply the power to undersea equipment in redundant arrangements called as dual end feed, for continuous operation even in the event of one PFE converter failure.
Different types of PFE from all SubSea suppliers available, depending on the power supply capability to feed the system, like 10Kv, 5Kv etc.

22. PFE – Submarine System powering overview
Current
Station A
PFE +
Station B
PFE -
Virtual Ground
Example of a Trunk Point to Point Powering System
PSBU 1
PSBU 2
Station A
PFE +
Current
Station B
PFE -
Station C
PFE -
Station D
PFE -
Example of a Normal Powering scenario for a Trunk and Branch Configuration

23. Fault Isolation & Repair in Wetplant
Detection and localization of Subsea faults
Two categories
- Optical
- Electrical
Electrical and optical faults can occur simultaneously (cable break) and separately (damaged or broken fibers with the power path intact, and insulation fault between the power path and the sea, commonly known as shunt fault, with fibers intact.

24. Types of SubSea Fault
Type 1 fault - Cable break for the cable being cut, with a break in the electrical insulation between seawater and
the power-feeding conductor.
Type 2 fault - Open fault for the cable being cut, without breaking the electrical insulation between seawater and the power-feeding conductor.
Type 3 fault - Shunt fault for a break in the electrical insulation between seawater and the power-feeding conductor, without this conductor itself been cut.
Type 4 fault - damage in the optical path without significant electrical alteration of the power-feeding conductor continuity and insulation.
Outer Cable
HV conductor
Fiber
Outer Cable

25. Fault Localization techniques
Single-end DC measurements Type 1- Cable Break Type 3 – Shunt Fault Only accurate if you precisely remove contribution of repeaters and fault.
Capacitive Method Type 2 - Open fault
Conjugate Method (current-balance) Type 3 – Shunt Fault Accurate but also requires removal of contribution of the repeaters.
Optical Path (OTDR/COTDR) Type 4 - Optical Fault only OTDR only good to first repeater.
Electrical Path fault Power Feed (output variation/ohms law) PEFL (impedance mismatch) DC Testing (IR, IC and CR) Electroding (detection of a magnetic field due to applied tone)

26. Optical Fault Localization
What is a OTDR?
Optical Time Domain Reflectometer - also known as an OTDR, is a hardware device used for measurement of the elapsed time and intensity of light reflected on optical fiber.
How it works?
The reflectometer can compute the distance to problems on the fiber such as attenuation and breaks, making it a useful tool in optical network troubleshooting.
The intensity of the return pulses is measured and integrated as a function of time, and is plotted as a function of fiber length.
What is a COTDR?
Coherent Optical Time Domain Reflectometer - also known as a COTDR, An instrument that is used to perform out of service backscattered light measurements on optically amplified line systems.
A fiber pair is tested by launching a test signal into the out going fiber and receiving the scattered light on the in-coming fiber. Light scattered in the transmission fiber is coupled to the incoming fiber in the loop-back couplers in each amplifier pair in a repeater.

27. OTDR Vs COTDR Repeater Repeater Repeater OTDR
HLLB
Repeater
HLLB
Light Pulse
OTDR
HLLB
Backscatter
OTDR can only measure up-to first repeater
Repeater
Repeater
HLLB
Repeater
HLLB
Light Pulse
COTDR
HLLB
Backscatter
OTDR can cross the repeaters & can measure till opposite end terminal

28. COTDR Measurement plot

29. Electrical path Fault Localization
Subsea cable Electrical path fault (Shunt Fault) localization is a manual process & no automatic measuring equipment/testers are available. This requires tedious calculations from PFE voltage & cable properties, before & after fault occurs. Below are some of the techniques used for this.
Power Feed (output variation/ohms law) – Using the simple ohms law formula for voltage/Impedance calculation, approx. fault location to be calculated. This is called power budget calculation.
Total PFE voltage(Segment voltage) = Cable voltage drop + BU drop + Repeater drop + earth resistance
PEFL (impedance mismatch)
DC Testing (IR, IC and CR) – This is normally done from cable repair ship for checking the cable continuity & post repair checks.
Electroding (detection of a magnetic field due to applied tone) from Terminal PFE.

30. Electroding
Electroding technique is sending low-frequency AC tone from Terminal PFE, using the capabilities of the PFE coupled & with special detection equipment
having low-current dc and low-frequency resistance and capacitance
measurements which can be used in repair ship to find out the exact fault.
Electroding is used for different purpose.
To identify the exact location of fault in a suspected span, either shunt or cable break from ship.
To identify & pickup the exact cable system, out of many cables laid on Seabed, during a repair activity from ship.
Fault Detected at Tone leakage point X
Electroding Signal Low frequency A.C tone
4Hz to 50Hz

31. Subsea Cable repair
The damaged Under Sea part of cable is repaired by specially equipped cable ships
A number of Cable ships are strategically located in different regions
Damaged portion of the cable will be lifted and removed by the cable ship and join again with a new piece of cable
The operation will take usually days depending upon the distance of cable fault, Nature of the fault, spare availability in the ship and weather conditions.

32. A Shunt Fault Shunt Fault – Shunt Fault –
Dual end PFE Feed, Not Service affecting
Shunt Fault –
Single end Feed, Service affecting

33. Cable Joints Sea Cable Joints
Cable joints connect similar types of cable on land and at sea during initial cable laying & during a repair operation.
Sea Cable Joints

34. Sub Marine cable System visual tour
Sub Marine cable system Video

35. CABLES AROUND AFRICA ► ►

36. Thank You!