Things You Should Know Before Choosing an OTDR

OTDR that is short for optical time domain reflectometry, is a fiber optic tester for the characterization of optical networks that support telecommunications. It can be used to measure loss, optical return loss (ORL) and optical distance on a fiber optic link. Besides, by providing pictorial trace signatures of the fibers under test, an OTDR can offer a graphical representation of the entire fiber optic link. However, there are so many OTDR brands in the market. Choosing the right OTDR for your application can be challenging. So this post is intended for giving some reminders when choosing an OTDR. Hope it may help you.


Why You Need an OTDR?

As we all know, fiber testing is an essential procedure to make sure that the network is optimized to deliver reliable and robust services without fault. So here are two reasons for why an OTDR is needed.

First, service providers and network operators want to insure that their investments into fiber networks are protected. Installers need to use OTDR performing bi-directional tests and providing accurate cable documentation to certify their work. Of course, OTDRs can be used for troubleshooting problems such as break locations due to dig-ups.

Second, premises fiber networks have tight loss budgets and less room for error. Therefore installers have to test the overall loss budget with a light source and power meter, which is a big task. While OTDR can easily pinpoint the causes for excess loss and verify that splices and connections are within appropriate tolerances, which saves lots of time. Besides, it is also the only way to know the exact location of a fault or a break.

What and Where Will You Test?

Before choosing a suitable OTDR, ask yourself the following two questions.

Loss, reflectance, splicing alignment and distance, which one are you going to test? Make sure the OTDR you choose can do what you want easily, quickly and accurately. If you need to make “live” test (like during a “hot cut”—splicing of fibers in a working cable), you need an OTDR that can do an active splice loss measurement in “real time”.

Where are you going to do testing? A good understanding of the applications of an OTDR will help you make the right choice for specific needs. For example, what kind of networks will you test? LAN (local area network), metro or long haul? What is the maximum distance you might have to test? 700 m, 25 km, 150 km?

What Should Be Focused on When Choosing an OTDR?

Many people may be familiar with OTDR but not know how to choose a real right one. Except for the quality that we must focus on, the following three factors also should be attached great importance to.

A Simplified and Task-focused User Interface

Maintaining fiber health is just as challenging and makes fast troubleshooting critical. Almost every OTDR on the market today is designed to cover carrier applications. As a result, many OTDR have very complex user interfaces which require the user to make sense numerous buttons and controls and navigate cumbersome multi-level menus. It’s bad for users improving operating efficiency. So a simplified and task-focused user interface test equipment is important.


Precision Fiber Channel Information

With the wide use of short patch fibers and various types of fiber connectors, details on network link—loss, connector and reflectance—are critical to ensuring performance. However, OTDR with an attenuation dead zone of more than 3m are no longer applicable for testing data center fiber. But when problems arise, an OTDR with precision fiber channel information can help users with various skill levels efficiently perform troubleshooting and accelerate network recovery.


Effective Planning and Documentation

As data centers grow and change, it’s challenging to ensure all fibers are installed with certificated quality. Therefore, integrated project management capabilities with cable-by-cable granularity can save time and planning effort. An OTDR with built-in project management capability that allows users plan day-to-day activities without using a personal computer or laptop.


Selecting a proper OTDR to test your network not only can strengthen its reliability, but also improve the efficiency of the testing job as well as documenting the quality of work. Therefore, before selecting an OTDR, considering the applications and specific needs of your testing work will ensure that it is suited for your applications. FS.COM provides various types of OTDR with different wavelengths such as 850 nm, 1310 nm, 1550 nm and 1625 nm. You can find one that best suits for your network.

Cable Fault Locator Introduction

When at some local point in a cable, insulation has deteriorated to a degree that a breakdown occurs allowing a surge of current to ground, the cable is referred to as a faulted cable and the position of maximum leakage may be considered a catastrophic insulation failure. After all clearances haven been obtained and the cable has been isolated in preparation for cable fault locating, it is strongly recommended that a fixed plan of attack be followed for locating the fault. As in diagnosing any complex problem, following a set step-by-step procedure will help in arriving at the solution or, in this case, pinpointing the fault efficiently. At the very start, it is a good idea to gather as much information as possible about the cable under test. Information that will help in the fault locating process is:

. Cable type-is is lead covered, concentric neutral (bare or jacketed), tape shield?
. Insulation type- is it XLPE, EPR, Paper?
. Conductor and size – is it CU, AL, standard, solid, 2/0, 350MCM?
. Length of the run – how long is it?
. Splices – are there splices, are the locations known?
. T-taps or wye splices – are there any taps, are the locations known, how long are branches?

Fault location on communication and power cables is a very specialized area of electrical technology. The performance of efficient fault location is very much dependant on good logistics and knowledge. Fast and reliable fault location is dependent on these factors if prelocation of a fault is to be done with high accuracy.

Cable testing, cable diagnosis and partial discharge measurements, will become of higher importance in the future. The condition based preventive maintenance of cable networks, will more and more replace the event oriented maintenance of cable installations.

A good detailed knowledge of the construction of cable networks, cable types and their accessories, simplifies the evaluation of the measured results considerably. Many of these are processes are the essential grounds for correct decisions to be made. The types of cable faults and required steps to do a cable fault location or a diagnosis are one of the most important details that the technician must be aware of.

The purpose of power cables is for the efficient distribution of electrical energy, distribution must be done with a high degree of reliability and safety over a very long period of time. Depending on the application, external environmental and local factors, for example, ground water level, type of ground or voltage levels, different types of cables are used. Cables with impregnated insulation, such as PILC, were installed until be late 60’s and are still being installed in some areas. These cables are today mostly replaced by cables with PVC, EPR, PR or XLPE insulation. Resulting from the changing characteristics of cables their faults and testing have changed considerably.

FiberStore supply a range of cable fault locators, such as Fluke 2042 cable locator, T-C310 cable fault locator, ST620 Cable Fault Locator and so on. As an professional optical communication products manufacturer, we also offer fiber optic tools and other fiber testers, welcome to contact us.

The Common Types of OTDR Test Equipments

OTDR is short for optical time-domain reflectometer, is an optoelectronic instrument used to characterize an optical fiber. It can offer you an overview of the whole system you test and can be used for estimating the fiber length and overall attenuation, including splice and mated-connector losses. It can also be used to locate faults, such as breaks, and to measure optical return loss. There are four types of OTDR, they are Full-feature OTDR, Hand-held OTDR, Fiber Break Locator, and RTU in RFTSs.

Full Feature OTDR

Full-feature OTDRs are traditional. They are feature-rich and usually larger, heavier, and less portable than either the hand-held OTDR or the fiber break locator. despite being characterized as large, their size and weight is only fraction of that of early generation OTDRs. Often a full feature OTDR has a main frame that can be fitted with multi-functioned plug-in units to perform many different fiber measurement tasks. Larger, color displays are common. The full-feature OTDR often has a greater measurement range than the other types of OTDR-like equipment. Often it is used in laboratories and in the field for difficult fiber measurements. Most full-feature OTDRs are powered from an AC source and or battery source.

Handheld OTDR and Fiber break locator

Handheld (formerly mini) OTDRs and fiber break locators are designed to troubleshoot fiber networks in a field-type environment often using battery power. The two types of instruments cover the spectrum of approaches to fiber optic plant taken by the communications providers. Handheld OTDR is more cheaper, more easy to use and light weight than full feature OTDR, sophisticated OTDRs to collect field data and perform rudimentary data analysis upon. They may be less feature rich than full feature OTDRs. Often they can be used in conjunction with PC based software to perform easy data collection with the hand-held OTDR and sophisticated data analysis with the PC-based software. 

The hand-held OTDRs are commonly used to measure fiber links and locate fiber breaks, points of high loss, points of high reflectance, link end-to-end loss, and Optical Return Loss (ORL) for the link. Fiber break locators are intended to be low cost instruments specifically designed to locate the position of a catastrophic fiber event, e.g., point of high reflectance, or high loss. The fiber break locator is an opto-electronic tape measure that is designed to measure only distance to catastrophic fiber events.

In general, hand-held OTDRs and fiber break locators are lighter and smaller, simpler to operate, and more likely to operate using battery power than full-feature OTDRs. The intent is for hand-held OTDRs and fiber break locators to be inexpensive enough for optical technicians to be equipped with one as part of their standard tool kit.

Remote Test Unit (RTU)

An RFTS enables fiber physical plant to be automatically tested from a central location. a central computer is used to control the operation of OTDR-like test components located at key points in the fiber network. These test components will scan the fiber to locate problems. If a problem is found, its location is noted and appropriate Operations Systems (OSs) are notified to begin the repair process. The RFTS can also provide direct access to a corporate database that contains a historical repository for the OTDR fiber traces and any other fiber records for the physical fiber plant.

Since OTDRs and OTDR-like equipment have many uses in the communications industry, their possible operating environment is varied, ranging from indoors to outdoors. Most often, however, these test sets are operated in controlled environments, accessing the fibers at their termination points on fiber distributing frames. Indoor environments include controlled environments such as in central offices (COs), equipment huts, or Controlled Environment Vaults (CEVs). Use in outside environments is rarer, but may include use in a manhole, aerial platform, open trench, or a splicing van.

FiberStore supply all kinds of OTDRs, our OTDRs are available with a variety of fiber types and wavelengths, including single mode fiber, multimode fiber, 1310nm, 1550 nm, 1625 nm, etc.. And we also supply OTDRs of famous brands, such as JDSU MTS series, EXFO FTB series, YOKOGAWA AQ series and so on. OEM portable and handheld OTDRs (manufactured by FiberStore) are also available. What’s more, we also offer many kinds of fiber optic tools. If you would like to know our OTDR price, please send your requirements to sales@fiberstore or visit our website.