Home > Articles > Networking > Wireless/High Speed/Optical

This chapter is from the book

Physical-Design Considerations

Many factors must be considered when designing a fiber-optic cable plant. First and foremost, the designer must determine whether the cable is to be installed for an inside-plant (ISP) or outside-plant (OSP) application. The answer to this question usually determines whether a loose buffer or a tight buffer cable will be used. An important factor in fiber-optic cable design and implementation is consideration of the cable's minimum bend radius and tensile loading. There are two kinds of submarine cable systems: shallow-water and deep-water systems.

Tight Buffer Versus Loose Buffer Cable Plants

Tight buffer or tight tube cable designs are typically used for ISP applications. Each fiber is coated with a buffer coating, usually with an outside diameter of 900 m. Tight buffer cables have the following cable ratings:

  • OFNR—Optical fiber, nonconductive riser rated

  • OFNP—Optical fiber, nonconductive plenum rated

  • LSZH—Low smoke, zero halogen rated

The type of ISP tight buffer cable selected usually depends on the application, environment, and building code. Loose-buffer or loose-tube cables mean that the fibers are placed loosely within a larger plastic tube. Usually 6 to 12 fibers are placed within a single tube. These tubes are filled with a gel compound that protects the fibers from moisture and physical stresses that may be experienced by the overall cable. Loose buffer designs are used for OSP applications such as underground installations, lashed or self-supporting aerial installations, and other OSP applications. These cables require additional cleaning, including the removal of the protective compounds when the fibers are to be terminated. Loose-tube cable designs include multifiber armored and non-armored cable systems.

Bend Radius and Tensile Loading

An important consideration in fiber-optic cable installation is the cable's minimum bend radius. Bending the cable farther than its minimum bend radius might result in increased attenuation or even broken fibers. Cable manufacturers specify the minimum bend radius for cables under tension and long-term installation. The ANSI TIA/EIA-568B.3 standard specifies a bend radius of 1.0 inch under no pull load and 2.0 inches when subject to tensile loading up to the rated limit.

For ISP cable other than two-fiber and four-fiber, the standard specifies 10 ∴ the cable's outside diameter under no pull load and 15∴ the cable's outside diameter when subject to tensile load. Cable tensile load ratings, also called cable pulling tensions or pulling forces, are specified under short-term and long-term conditions. The short-term condition represents a cable during installation and it is not recommended that this tension be exceeded. The long-term condition represents an installed cable subjected to a permanent load for the life of the cable. Typical loose-tube cable designs have a short-term (during installation) tensile rating of 600 pounds (2700 N) and a long-term (post installation) tensile rating of 200 pounds (890 N).

Submarine Cable Systems

Shallow-water systems are similar to their armored loose-buffered terrestrial counterparts, whereas deep-water submarine cables use a special hermetically sealed copper tube to protect the fiber from the effects of deep-water environments. Deep-water and submarine cables also have dual armor and an asphalt compound that is used to fill interstitial spaces and add negative buoyancy. In addition to the significant external physical forces that might be encountered in a submarine environment, the other major concern is the effect of hydrogen on the performance of the optical fiber in cables used in such applications.

The effect of hydrogen on fiber performance depends on specific system characteristics. System attributes include fiber type, system operating wavelength, and cable design and installation method. Hydrogen can chemically react with dopants, such as phosphorus, to produce irreversible absorption peaks, resulting in a significant increase in the attenuation coefficient across various wavelength ranges. This phenomenon, also known as the Type 1 hydrogen effect, occurred primarily in early optical-fiber designs that used a phosphorus dopant. Unlike early phosphorus fibers, current fibers using germania dopants are not susceptible to Type 1 hydrogen effects.

The second hydrogen effect arises from the propensity for molecular hydrogen to diffuse readily through most other materials. When diffused into glass optical fiber, hydrogen creates distinct absorption peaks at certain wavelengths. The most predominant of these occurs at 1240 nm and 1380 nm. The tails of these peaks can extend out, depending on the hydrogen concentration, affecting the optical performance at 1310 nm and 1550 nm. Unlike the Type 1 effect, the effect created by molecular hydrogen is reversible and is known as the Type 2 hydrogen effect. The major sources are typically understood to be the corrosion of the metal armoring and the presence of bacteria. Proper span design must take into consideration hydrogen safety margins for submarine applications. The attenuation coefficient is proportional to the water depth role because as depth increases, the partial pressure of hydrogen increases, resulting in an increase in the amount of interstitial hydrogen that can be present in the fiber.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020