white paper FTTP A fiber-to-the-premises (FTTP) distribution network, by its very nature, requires numerous interfaces and connections to route traffic between the end user and the central office. There is a fine line between maintaining a flexible and easily-accessible infrastructure and still achieving reasonable distances that are easily and effectively managed. The decision to use splices or connectors at particular junctures requires careful consideration, but a simple rule of thumb would be to splice connections that will remain permanent and use connectors wherever a need for future access may occur. Unfortunately, it isn’t always that simple. Consideration must also be given to the cost economics, skill sets requirement, slack storage, signal loss, environment, and physical network characteristics. Technician skill sets and equipment Traditionally OSP networks used splicing exclusively as a means of interconnecting cables. However, where a distribution network is involved, splicing could be a very expensive and time- consuming operation. Since distribution networks require numerous connections for quickly turning up services to thousands of homes and businesses, connectors offer more flexibility and less personnel training to accomplish. Therefore, the number of technicians and equipment required for multiple splicing operations must be considered. Ease of access The mythical “seamless” network may have appeared as a good solution for transport and backhaul operations, but with an access network, the ability to easily test and monitor is essential. Connectors enable easier access for troubleshooting and maintenance operations. They provide access at multiple points along the network and are certainly simpler than cutting into the cable to perform these same operations. Without seams provided by connectors, there is no access or ability to physically restore a network outside of cutting into the optical cable. Other considerations The risk of inadvertent failure also increases when cutting and splicing cables, leaving a possibility of service interruption or failure to other customers while troubleshooting a problem in another area of the network. To most service providers, this is an unacceptable risk. (Should address any other considerations here) Connector improvements Vast improvements have taken place in fiber connectivity over the years that have improved their performance in the network. Higher performance standards and manufacturing improvements have resulted in lower insertion and return loss, automated tuning, superior endface workmanship, and vastly improved factory termination methods. Connector performance is typically measured in two ways. First, the optical and mechanical specifications the connector meets out-of-box – specifically, insertion and return loss. Insertion loss is the amount of light lost and return loss is the amount of light reflected back towards the source. Second is how these parameters change over the lifetime of the connector, typically characterized by performance to GR-326-CORE Issue 3. ADC excels in each of these Splicing vs. connectorization in FTTP networking 2 measurements by offering industry-leading optical and mechanical specifications, backed by independent third-party test data. • Better core alignment process – ADC has chosen an automated process rather than a manual process, relying less on human intervention, giving more accurate and consistent core locations, and dramatically reducing the potential for damage to the endface. While some manufacturers may tune connectors manually in an attempt to lower cost, cutting corners when it comes to the quality and performance of connectors in a network should not be an option. • Automated tuning process – Tuning refers to the alignment of the connector ferrule, such that any offset from the nominal position of the fiber end is aligned within an angular tolerance zone around a key feature on the connector body. The performance of optical connectors, when mated to a reference connector, is not a true test of how the connectors will perform when randomly mated in a service provider’s network. Randomly mated connector pairs traditionally produce a greater insertion loss than the stated specification of either connector to a reference connector. This occurs when the fiber ends of individual connectors are misaligned in opposite direction from the nominal position and, thereby, create a greater total misalignment. An automated tuning process significantly reduces insertion loss in paired connectors by accurately aligning the fiber end offset of each connector in a common direction. Anytime a tuned connector is inter-mated with any other tuned connector, the insertion loss of the randomly inter-mated pair is minimized. • Lower losses – ADC achieves lower return loss in fiber-optic connectors by mating the connector to a master, or reference, connector. Whenever return loss is measured without using a master connector, the two connectors each have an index layer that increases return loss on the connection. However, when measuring to a master, the connector under test has an index layer and the master is assumed to have none, resulting in lower return loss on the connection. Proper tuning reduces insertion loss by improving the alignment of the fiber cores in mated pairs. The accuracy of the 3 tuning process has a direct affect on randomly inter-mated connector performance and is improved through an automated process. • Superior endface workmanship – Consistent endface geometry gives more consistent core-to-core contact under all operating conditions, such as temperature swings and humidity, and provides a good seal to prevent debris from migrating to the core during operation. Improved endface geometry is indicative of a very repeatable, high quality, manufacturing process. ADC measures and provides data for each of the following quality measurements: apex offset to <50 microns; fiber recess to +/- 50 nanometers; and radius of curvature to 10-25 millimeters. In terms of endface visual inspection workmanship, ADC has integrated manufacturing and measurement techniques that produce extremely consistent products. This translates to flawless performance in the field, regardless of which two connectors end up mated together. • Factory termination – Network operators have long faced the question of whether it is more cost effective to terminate fiber panels in the field or purchase pre-connectorized fiber panels from the manufacturer. Field termination requires a dedicated labor force to load, install and terminate panels on-site. Labor costs accrue quickly and reliability is jeopardized as possible human error puts proper panel connectorization – and, ultimately, network performance – at risk. Factory connectorization minimizes installation expense and maximizes network performance by eliminating additional labor costs and termination gaffes in the field. Manufacturers understand the complexities of their own panels and the optimal methods for termination, eliminating costly “do it again” scenarios by offering accurate panel termination the first time at the factory. Today’s competitive business environment leaves little margin for error when deciding how to architect a FTTP network – therefore, the decision to splice or connect in an optical fiber network can be a critical one. Both methods have benefits in certain situations, but it’s important to at least realize that connectors have vastly improved in recent years. These manufacturing improvements enable them to offer optimal performance while providing cost and flexibility benefits that cannot be attained through splicing alone. 4 ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101 Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, ADC reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our headquarters office in Minneapolis. ADC Telecommunications, Inc. views its patent portfolio as an important corporate asset and vigorously enforces its patents. Products or features contained herein may be covered by one or more U.S. or foreign patents. An Equal Opportunity Employer 1288429 4/04 Original © 2004 ADC Telecommunications, Inc. All Rights Reserved Web Site: www.adc.com From North America, Call Toll Free: 1-800-366-3891 • Outside of North America: +1-952-938-8080 Fax: +1-952-917-3237 For a listing of ADC’s global sales office locations, please refer to our web site. . performance to GR-326-CORE Issue 3. ADC excels in each of these Splicing vs. connectorization in FTTP networking 2 measurements by offering industry-leading optical. Site: www .adc. com From North America, Call Toll Free: 1-8 0 0-3 6 6-3 891 • Outside of North America: + 1-9 5 2-9 3 8-8 080 Fax: + 1-9 5 2-9 1 7-3 237 For a listing of ADC s