How to Choose an OTDR? (Optical Time Domain Reflectometer)

The field of network communication has seen a growth in the use of optical Fibre during the last few years. A more precise and speedier methodology for evaluating the integrity of the infrastructure is essential to ensuring that the Fibre network is dependable and accessible.

Consequently, it is crucial to pick the appropriate Fibre optic testing instrument or device to satisfy the upgraded testing needs and contribute to improving the value and reliability of the entire network. One of the most effective test tools for Fibre cable testing is the OTDR (Optical Time Domain Reflectometer).

OTDR

It is a Fibre optic tool that analyzes, manages, and describes optical communication networks. By sending and examining pulsed laser light that is flowing through an optical Fibre, OTDR testing is carried out. Because the light is inserted at the end of a Fibre optic cable link, the measurement is considered unidirectional.

The OTDR performs as an optical radar system, giving users thorough information on the location and overall health of connections, flaws, and other significant features. This information is acquired from the following light signature reflected or scattered back to the point of origin.

In simple words, Optical time domain reflectometers are essential for maintaining Fibre communication systems. An OTDR creates a pulse inside a Fibre to check for flaws or problems. Several internal processes in the Fibre lead to a Rayleigh backscatter.

The OTDR receives the pulses back, measures and calculates their strengths as functions of time, and plots the results as functions of Fibre stretch.

 The strength and strength of the returned signal indicate the issue’s location and severity. OTDRs are used in both maintenance and optical line installation services. Moreover, OTDRs are used by the network’s poles and nationwide telephone exchanges to ensure smooth operation.

By examining the reflected light in the cables, OTDRs measure Fibre cables. An OTDR can measure various things, such as:

• Loss of Splices and Optical Distance To Connectors, Splitters, Faults, etc., and The End Of The Fibre Cable
• Total Fibre Attenuation ORL Of Link Reflectance Of The Connectors

Working principle for OTDR

OTDR testing would only be as accurate and useful as the science that came before it. Understanding the device’s mechanics offers priceless insight into how the OTDR operates. The idea that electrons may be induced to emit a certain waveform was first proposed by Albert Einstein, and this idea planted the seed for the eventual development of the first functional laser in 1960.

 Although Fibre optics have now come to be associated with connection in the twenty-first century, the applications envisioned at the time presumably did not include international telecommunications employing this technology. The development of OTDR testers has benefited greatly from numerous ground-breaking discoveries over the years.

Types of OTDR

The variety of product offerings keeps expanding as the functional utility of OTDR testing rises, along with the requirement for improved testing speed, accuracy, report production, and storage capabilities.

The two main categories are bench-top and handheld. Instead of a bench-top OTDR, a feature-rich instrument with a direct AC power source, a handheld or mini OTDR is a lightweight, battery-operated device for use in the field.

The type of Fibre you will test multimode, single-mode, or both is crucial. The length of the Fibre you will test is another variable. Items designed for the long haul testing shorter Fibre optic networks like FTTA would not require the higher dynamic range capabilities normally seen in products made for long-haul applications.

• Because usability characteristics vary depending on the model, the most important element in product selection should be the intended application for the OTDR (Import factors for choosing an OTDR).

For instance, a lightweight product might not be required for a test that is done stationary. Still, suppose specialists will climb base stations or perform the evaluation in another physically demanding environment. In that case, aspects like weight and ruggedization of the product enclosure become more crucial.

Why do we need OTDR?

Fibre testing is crucial to ensure the network is optimized to deliver dependable and robust services without interruption.

Outside Plants

Network operators and telecom, video, and data service providers seek to safeguard their investments in Fibre networks. Every cable in an outdoor Fibre optic plant must undergo an OTDR test to guarantee the installation was done correctly.

To provide proper cable certification and authenticate their work, installers must use loss test sets (source and power metres) and OTDRs. Eventually, OTDRs can be used to address issues like dig-up-related break locations.

Premises, LAN/WAN, Data Centers, Enterprise

Network owners and contractors ponder whether they should test premises cabling with OTDR. They also want to know if OTDR testing can replace the traditional loss testing approach that uses a power metre and a light source.

Premises Fibre networks have limited margins for mistakes and strict loss budgets. Installers will test the entire loss budget using a light source and power metre (Tier 1 certification required by TIA-568C standards).

A recommended practice that can identify the root causes of excessive loss and confirm that splices and connections are within acceptable tolerances is OTDR testing (Tier2 certification).

Also, it is the only technique to locate a flaw or break precisely. Using an OTDR to test a Fibre link also helps to document the system for further verification.

Three Important Considerations While Selecting an Optical Time Domain Reflectometer

• Configure the parameters of your OTDR system.

Grandway OTDR test series include FHO 1000 portable series, FHO 3000 mini-series, FHO 5000 series, etc. Grandway offers a broad range of OTDR alternatives to fulfill the demands of various optical network tests. The newest smart handheld OTDR from Grandway is the FHO 1000.

Despite being a handheld OTDR, it can measure Fibre lengths of more than 100 kilometers. With outstanding 1m/4m dead zone performance in short-distance Fibre testing, different events like straight connectors, attenuation loss, etc., may be detected clearly.

• Clarify your OTDR working environment.

When selecting a field instrument, the temperature standard may be the most demanding for users and buyers because field measurements frequently need to be made in challenging conditions. It is advised that the field instruments’ operating temperatures range from -18°C to 50°C, and their storage and transit temperatures range from -40°C to 60°C (95%RH).

Laboratory equipment must only function within a small five °C to 50°C control range. On-site opening, acceptance, and maintenance testing of optical Fibre communication systems using handheld OTDRs. The location is perfectly suited for the operating temperature range of -10°C to 50°C and the storage and transit temperature range of -40°C to +60°C.

Field portable equipment typically has harsher power needs than laboratory instruments, which AC can power; otherwise, it will hinder work efficiency. In addition, the power supply issue of instruments is frequently a significant factor in instrument failure or damage. The Grand-way handheld OTDR uses a lithium rechargeable battery and an AC charger to address the power supply issue.

Comparative performance key performance indicators for OTDR

The following are the Comparative performance key performance indicators for OTDR:

1. Dynamic range

This index establishes the maximum Fibre length the OTDR optical time domain reflectometer can measure or the highest optical loss value it can evaluate. The further the distance can be analyzed by OTDR, the higher the dynamic range. In particular, dynamic range should be carefully examined for two reasons:

1. OTDR manufacturers may employ several techniques to determine the dynamic range (such as pulse width, signal-to-noise ratio, averaging time, etc., defined by the index). Thus, a thorough comprehension of this index is required to avoid mistakes caused by dissimilar premises and objects while comparing various instruments.
2. The length of the entire link can only be evaluated if the dynamic range of the OTDR is sufficient. In many circumstances, this will impact the complete link loss, attenuation, and remote connector test accuracy. One rule of thumb is choosing the OTDR’s true dynamic range value, which should be 5 to 8 dB higher than the maximum loss it might experience.

b)  Dead zone (attenuation dead zone and event dead zone)

The dead zone is a crucial index to consider when assessing an OTDR’s performance because it dictates whether or not the entire link can be accurately tested. Dead zones typically fall into one of two categories:

1. Event dead zone:

The smallest distance the OTDR can discern between two reflection events is called the “event dead zone” index. That is the capacity to differentiate between two events. If a reflection event is in the dead zone of its last event, it cannot be recognized or appropriately tested. The range of 1 to 5 meters is considered the industry standard.

2. Attenuation dead zone:

The attenuation dead zone is an index that measures how far away from a reflection event the OTDR must be to appropriately evaluate the loss of a subsequent reflection event or non-reflection event. A brief timeout Short optical jump lines or short distance Fibres can be tested using OTDR, and the shorter the dead zone, the better the result. This index typically ranges from 3 to 10 meters according to industry norms.

3. Linearity

The OTDR’s capacity to muffle noise is known as linearity. The instrument’s linearity is crucial because it directly affects the accuracy of the loss test of the Fibre, including the reliable result of the loss brought on by the splice or Fibre macro bend. According to industry norms, the linearity index ranges from 0.03 dB/dB to 0.05 dB/dB.

4. Resolution sampling

The minimum distance between two adjacent sample locations is called sampling resolution. The accuracy of the test distance and the ability of the OTDR optical time domain reflectometer to locate the fault spot can both be impacted by this parameter, which is equally significant. This variable is connected to pulse length and width.

FAQs

What is the best OTDR?

The Top OTDR Testers Includes:

• the EXFO OTDR Singlemode 1310/1550nm MAX720C Access SC/APC.
• 3-in-1 CWDM/DWDM/PON ShinewayTech OTDR
• MTP-200 handheld 1310/1550 nm 32/30 dB Testing Machine for OTDR HSV-610.
• The OTDR for Fluke Networks OptiFibre Pro.

Which fibre optic cable kind is the best?

The OS2 fibre optic cable type offers the best performance over greater distances and is also more robust.