Otdr span orl

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This property is essential for maintaining signal integrity and avoiding disruptions in optical communication systems.

Impact on Network Performance

Reflections within an optical link aren’t just minor hiccups—they can lead to serious network issues. Always ensure consistent connector types across the system for the best results.

Best Practices for Minimizing ORL

Maintaining low ORL throughout the network requires adherence to several best practices:

  • Always clean before connecting – Dirt and debris at connection points can increase reflectance.



    OCWR Testing
    Below is a diagram of a typical setup for reflectance or return loss tests of connectors or patchcords per industry standards (TIA FOTP-107 or IEC 61300-3-6) using a light source and power meter. But a reference trace, from the commissioning dropped and blocked sweeps, makes it easy to see changes.

    The ARRL Handbook defines return loss as: “a measure of how closely one impedance matches a reference impedance in phase angle and magnitude. Some OTDRs can also calculate ORL for this same definition.


    Reflectance Testing By OTDR
    The OTDR  can measure the amount of light that's returned from both backscatter of the fiber and reflected from a connector or splice, leading to two independent tests, reflectance and optical return loss.

    That connection will typically consist of a reference connector which is used to mate to the connector under test. The method sends light from a source through a coupler to the connection that is being tested. The index matching gel used for mechanical splices works well, but mineral oil or alcohol works fairly well too.

    ORL measures the amount of optical signal reflected back toward the source from various points in the network. A simple cleaning may resolve the issue entirely.

    • Use angled (APC) connectors where appropriate

    APC connectors offer superior performance by minimizing back reflections.

    • Re-terminate faulty splices

    Ensure splices are executed with precision to reduce unnecessary signal reflection at junctions.

    • Use proper dust caps and inspect for physical damage

    Protect components and regularly check for cracks, scratches, or other visible defects.

    Proactive ORL Management

    Staying ahead of ORL issues relies on consistent, preventive strategies.

    The technique involves polishing the end surface of the fiber to a convex surface to ensure proper fiber contact. This is why this is a patchcord test, as long cables are not possible to test this way.)



    The power meter reads -41.9 dBm. In fact, when the power meant to be radiated comes back into the transmitter at full strength, it will usually burn out the electronics there.

    For instance, 40 dB or greater is ideal for high-speed connections.

    • Relevant Industry Standards 

    Several industry standards provide guidance and minimum requirements for ORL in fiber optic systems. We need to calibrate the measurement for the coupler, let's add 3.5 dB, so we have -38.4 dB down from the 0 dBm test signal or a reflectance of -38.4 dB (ORL 38.4 dB.) Since Our noise floor was -60 dBm, or ~ 1% (-20 dB) of the reflectance we measured, we can ignore it.

    OCWR and Long Cables
    The OCWR technique is really designed to work on patchcords.

    While it’s natural to have some level of reflection, excessive ORL can degrade signal quality and cause network inefficiencies.

    Common Sources of Reflection 

    • Poor connector end-face quality or contamination
    • Air gaps between connectors
    • Mechanical splices with mismatched cores
    • Breaks or microbends in the fiber

    Each of these factors disrupts the intended flow of light, creating unnecessary reflections that increase ORL and negatively affect performance.

    Examples of High-ORL Scenarios 

    To illustrate these challenges, consider these situations where ORL frequently becomes problematic:

    • Dirty SC connectors in a patch panel
    • Improperly mated APC connectors with UPC types
    • Unused ports left open without dust caps

    These seemingly minor issues can lead to significant reflectance, making it crucial to adhere to best practices in handling and maintenance.

    The Role of Connectors and Termination Quality 


    The quality of connectors and terminations plays a pivotal role in minimizing ORL.

    For example, APC connectors are specifically designed to reduce reflectance by angling the end-face. The information contained in this document is the property of JDSU. 1-13 Types of Shields .

    • Understanding Optical Time Domain Reflectometers (OTDR) Specifications

      WHITE PAPER Understanding Optical Time Domain Reflectometers (OTDR) Specifications December 2020 | Rev.

      A00 P/N: D08-00-087 VeEX Inc. 2827 Lakeview Court, Fremont, CA 94538 USA Tel: +1.510.651.0500 Fax: +1.510.651.0505 www.veexinc.com Understanding Optical Time Domain Reflectometers (OTDR) Notice: The information contained in this document is subject to change without notice.

      otdr span orl