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Fibre Management Questions
Q: What are the differences between single circuit and single element fibre
management?
A: Single circuit fibre management splits the cable element into individual or
pairs of fibres (i.e. transmit and receive). This isolates each individual fibre or pair of fibres
from other fibres / circuits held within in a cable element by storing them in individual splice
trays. Splitting the fibres into single circuit allows easy distribution of the circuit into the
network and offers an excellent point of flexibility.
Single element management allows storage of up to12 fibres per splice tray (i.e. 6 circuits)
and increases the capacity of the connectivity equipment. Single element management offers less
flexibility over the routing and maintenance of the individual circuits / fibres but an increased
fibre splice density is achieved.
Q: Why should I choose to manage fibre on a single circuit basis?
A: Single circuit management allows isolation of individual customers and hence
reduces the risk of interference with adjacent fibre circuits in case of maintenance /
reconfiguration of the network. This is particularly important when transmission rates are at high
bit rates. Single circuit working also allows individual fibres / circuits to be assigned to
individual customers and distributed out from the cable element to offer flexibility when routing.
Q: Do Prysmian provide solutions for both single circuit and single element fibre
management?
A: Single element and single circuit solutions exist within the OAsys product
range for all areas of the network build.
Q: What is a patch cord?
A: A patch cord is an optical cable used for linking (or patching) between optical
sources. Demountable optical connectors (Terminations) are fitted to each end of the cable. The
connectors may be either of the same type or alternatively have a different connector type fitted
to each end. Patch cords may sometimes be referred to as either SIMPLEX or DUPLEX.
• SIMPLEX - refers to a Single Fibre Cable (SFC) with a single
termination at each end
• DUPLEX - refers to a Double Fibre Cables (shotgun or zipcord) with
double terminations at each end.
Q: What is a pigtail?
A: A pigtail is an optical cable link used for connecting between optical sources.
A demountable connector is fitted to one end of the cable and the opposite end is fusion spliced on
to a network fibre.
Q: What does the term Insertion Loss (IL) mean?
A: This is the measure of light lost at the connector interface in decibels (db).
The loss is usually quoted as per mated pair of connectors.
Typical IL values would be 0.2db to 0.5db depending upon the Fibre and Connector type.
Q: What does the term Return Loss mean?
A: This is a measurement of light "reflected" from the Connector Face and returned
back down the fibre, sometimes referred to as "Back Reflection Loss". Return loss is measured in
decibels (db) and is always quoted by the manufacturer for Single Mode Fibres as the light
returned/reflected back to the origin can affect the Laser producing the light and causing "noise"
problems.
Typical RL values would be between 30db and 60db depending upon the Connector Type and end
face finish polishing. The higher the Return Loss figure the better the Connector as this indicates
the level of light returned down the fibre. Return Loss (RL) is never quoted for Multi Mode Fibres
generally because the Light Sources used in MM systems are LED's.
Q: What types of connectors are available?
A: Many different types of connectors are used throughout the world but the most
common are detailed below:-
ST (Straight Tip) - most commonly used for Multi Mode fibre systems, the connector
provides Physical Contact (PC) properties by spring loading of the ferrule. A bayonet keyed fixing
method maintains accurate alignment of the ferrule. They may also be used for some Single Mode
Fibre systems where high Insertion Loss (IL) and low Return Loss (RL) can be tolerated. Available
only as simplex connectors.
FC (Fibre Connector) - most commonly used connector for low loss Single Mode Fibre
systems but also used for Multi Mode systems as well. Physical Contact (PC) properties are
maintained by spring loading of the ceramic ferrule. Accurate alignment is maintained by the use of
key way and threaded connector retention. Most optical test equipment, such as OTDR's, are fitted
with FC connection output facilities to maintain accuracy of measurement. Available only as simplex
connectors.
SC (Subscriber Connector) - Next most commonly used connector, to the FC, for
Single Mode Systems but also used for low Insertion Loss (IL) multimode systems. Offers higher
packing density of connectors in a patch panel with quick make and break connections. Physical
Contact (PC) properties are maintained by spring loading of the ceramic ferrule. Accurate alignment
is maintained by use of key way and push in connector retention. Used in preference to FC
connectors as the adapters for the connectors are less expensive. Available in both Simplex and
Duplex formats.
E2000 Connector - Becoming more commonly used within Fibre networks particularly
in continental Europe . Generally only used for Single Mode systems. Very similar in operation to
the SC but has built in end face covers that automatically open on connection in to the adapter and
protect personnel from eye damage due to high intensity LASER light. Provides a more secure locking
system than SC types. Connectors are more expensive than either FC of SC types. Available in both
Simplex and Duplex formats.
DIN Connectors - Manufactured in accordance with DIN 47256 and the connector
offers similar features to the FC type connectors. Connectors are of a more compact design than FC
types and therefore offer a higher density of Patch panel population. The cost of the connector can
sometimes be prohibitive, 2 to 3 times greater than the cost of FC connectors. Available as Simplex
connectors only. LC (Lucent Connector) - Similar to SC types but a more compact design and it
offers a pull proof design mechanism. Sometimes referred to as Small Form Factor (SSF) Connectors.
Connector cost generally more expensive than SC types. Available in both Simplex and Duplex
formats.
Q: What is meant by the connector end face type and finish?
A: The IL and RL measurements can be improved by altering the contact surface
between the fibres and connector. Surfaces can be cut at different angles, and polished to
different levels. The different types of finish available are detailed below.
PC (Physical Contact) - Most generally used end face finish for all connector
types. The connector is supplied with a polished radiuses convex face to give Physical contact at
the fibre core interface.
Insertion Loss <= 0.4db
Return Loss >= 30db
SPC (Super Polished Physical Contact) - End face shape is the same as the standard
PC connector but and additional fine polish is applied to the face of the connector to improve both
insertion and return loss.
Insertion Loss <= 0.3db
Return Loss >= 45db
UPC (Ultra Polished Physical Contact) - End face shape is the same as the standard
PC connector but and an extra fine polish is applied to the face of the connector to improve both
insertion and return loss.
All Prysmian patchcords and pigtails are supplied to this standard.
Insertion Loss < 0.3db
Return Loss >= 50db
APC (Angle Polished Physical Contact) - End face geometry is changed to produce an
angled end shape (usually 8 0 ) and polished to UPC standard. This improves both IL and RL of the
connector and makes them suitable for high quality low loss Single Mode systems. APC connectors are
used exclusively for Single Mode systems. Connectors are identified with a GREEN colour code either
on the connector body or boot. In general APC format connectors are limited to FC, SC and E2000
types. Special colour coded adapters are also available for these connector types.
Insertion Loss < 0.3db
Return Loss >= 60db
Q: What are Adapters (or Uniters )for connectors?
A: Adapters (sometimes called uniters) are used to link together two connectors of the same
type or of different types.
A variety of adapters are available for all connector types to fit either pre-cut holes in
patch panels or for bulkhead applications. Hybrid adapters are also available these allow
connectors of different types to be connected to each other e.g. ST to FC, FC to SC etc.
The adapters are provided with an internal split sleeve to provide an accurate fit on the
connector ferrule. Two types of sleeve are available either Phosphor Bronze or Ceramic (Zirconia),
there is very little to choose between the sleeve materials but where high make and break of
patched circuits is likely then Zirconia sleeves offer better wear properties.
All standard adapters supplied by Prysmian have Ceramic Zirconia sleeves.
SC, LC and E2000 adapters are supplied with colour-coded bodies to indicate the Fibre Type
or connector format; some of the most common colours are shown below.
• Beige - Multi Mode.
• Blue - Single Mode PC, SPC, UPC.
• Green - Single Mode APC.
Adapters for FCAPC applications are supplied with GREEN end caps to indicate
that they are suitable for APC connection.
Q: What type of splice trays do the OAsys® products contain?
A: A variety of splice trays are used within the product range which are designed
for optimum use within the product space, and also for its specific application. All splice trays
are designed to actively manager the optical fibre to a minimum bend radius of 30mm. Most of our
products contain one of two splice trays:
• OAsys® Splice tray single element - Capacity up to 12 splice
protectors, ability to store dark fibre in central mandrel, bend managed at all points to Ø60mm,
One entry port, One exit port. In addition to the splice tray a variety of manifolds are available
to manifold and distribute the fibres.
• SSF12 Splice Tray - Capacity up to 12 heat shrink or crimp splice
protectors or 6 Mechanical splices. Ability to store dark fibre in central mandrel, bend managed at
all points to Ø60mm. Up to 6 entry / exit ports to accommodate a variety of tube types from Ø0.9mm
to Ø5mm. A Clear plastic removable cover offers effective protection to the fibre.
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