EXFO Patente

Systems and methods for fast testing of an optical fiber network are provided. A main testing unit and a remote testing unit are optically coupled to opposite extremities of first and second FUT of the network, Each testing unit has a a reflectometric branch with a light source and light detector, and a power meter branch with a power meter but devoid of light sources. Each testing unit also includes a primary switching stage having two unit-side ports optically coupled to the reflectometric branch and power meter branch, respectively, and two network-side ports optically coupled to the first and second FUTs, respectively. In use, optical test signals can be sent from opposite test units into the two FUTs to double the acquisition speed compared to traditional techniques.

A method of locating a hollow-core fiber segment amongst silica core segments in optical fiber link is provided. An OTDR test instrument sends test signals along the fiber link and a Rayleigh backscatter level as a function of distance along the optical fiber link of returning signals is measured. The position of the proximal extremity of the hollow-core optical fiber segment is identified by locating a discrete drop greater than a drop threshold value in the Rayleigh backscatter level. The position of the distal extremity of the hollow-core fiber segment is identified by locating one of a discrete step greater than a step threshold value in the Rayleigh backscatter level and end-of-fiber indicator. The drop threshold value and the step threshold value are commensurate with a difference between a Rayleigh backscatter level in hollow-core optical fibers and in the type of silica core optical fibers of the optical fiber link.

Systems and methods (100) of mobile network synchronization domain anomaly identification and correlation include steps of receiving (102) measurements from a synchronization domain (20) reflecting the performance of synchronization across a mobile network (10); identifying (104) synchronization domain anomalies in the measurements from the synchronization domain (20); correlating (106) of the synchronization domain anomalies against anomalies from other domains (14, 16, 18) of the mobile network (10); and one or more (108) of (1) identifying root causes of the synchronization domain anomalies and the anomalies from other domains (14, 16, 18), (2) identifying associated impact on services and/or subscribers of the synchronization domain anomalies and the anomalies from other domains (14, 16, 18), and (3) identifying remedial actions for the synchronization domain anomalies and the anomalies from other domains (14, 16, 18).

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Methods and systems for referencing an optical power loss measurement (OPLM) system, and methods and systems for measuring an optical insertion loss of an optical device under test (DUT) using an OPLM system referenced as such. The herein-provided reflectometric one-cord referencing method combines the capabilities of an OPLM system with that of an Optical Time Domain Reflectometer (OTDR). A first test unit comprises an optical source that is used as the light source in the OPLM. A second test unit comprises a power meter which is used as the power meter in the OPLM measurement. Either the first or the second test unit comprises an OTDR acquisition device. The reflectometric one-cord reference measures the connector loss along the reference link using OTDR capabilities of the test unit(s). Once the power reference of the OPLM devices is obtained, the reflectometric one-cord reference method may determine the optical insertion loss of the DUT while eliminating the measured connector loss.

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In order to assist in determining the physical nature of an optical event as monitored by an OTDR in an optical fiber network, there are herein provided OTDR methods and system which leverage historical values measured on reflective events for characterizing events along an optical fiber link. A plurality of OTDR acquisitions is performed toward the optical fiber link over a period of time. Parameters characterizing a target event are derived using the recorded OTDR acquisitions. One of said parameters represents a stability, over the period of time, of a reflectance peak level associated with the event. The event is classified at least based on said stability.

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There is provided a photonic integrated apparatus for determining an orientation and/or a position of an optical waveguide, by measuring a relative intensity and a relative phase difference of the probe light signal incident on a sensor array. The phase profile of the probe light signal projected spatially on the sensor array is particularly sensitive to small changes in the optical probe's orientation and distance. The apparatus measures the relative intensity and relative phase difference of the probe light signal incident on a sensor array. A photonic integrated sensor circuit comprises the sensor array and one or more optical interferometric circuits. Changes in the sensed relative intensity and relative phase difference of the probe light signal, as sampled by the sensor array, indicate variations in the relative orientation and/or distance between the optical waveguide and the sensor array.

A method (100) includes obtaining (102) a first Quality of Experience, QoE, measurement (30) from a first content source (16); determining (104) a QoE adjustment factor (32) based on a predictive model; and adjusting (106) the first QoE measurement (30) using the QoE adjustment factor (32) to obtain a second QoE measurement (34), the second QoE measurement (34) reflects a QoE estimate from a second content source (18). The first content source (16) can be a Content Delivery Network, CDN, entity, and the second content source (18) is an Over-the-Top, OTT, content provider.

In an embodiment computer-readable training data records characterizing operation of a communication network may be used to train a machine learning (ML) model of network performance to predict expected performance characteristics, each training data record including operational features and observed performance characteristics of the communication network. The ML model may compute mappings of feature-values pairs to predicted performance characteristics. For a first subset of training data records, a fair distribution of first quantitative contributions of operational features of predicted performance characteristics may be computed, the first subset representing a baseline of observed performance characteristics. For a second subset of training data records, a fair distribution of second respective quantitative contributions of predicted performance characteristics may be computed, the second subset representing a problematic performance characteristic. Comparing the first and second quantitative contributions may determine a degradation metric for associating operational features of the second subset with the problematic performance characteristic.

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There is provided a method of measuring the PMD of an optical fiber under test (FUT). A polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT and from a proximal end thereof, a test signal comprising a series of repeated light pulses and detecting a corresponding polarization-analyzed return light signal coming back from the optical fiber and representing back-reflected light from a light reflector connected to a distal end of the FUT, said return light signal comprising repeated reflected light pulses. The plurality of polarization-sensitive acquisitions defines at least one pair of acquisitions performed with mutually different but closely-spaced wavelengths and substantially the same state of polarization (SOP), a center of said wavelengths defining a center wavelength for said at least one pair. The process may be repeated for a plurality of pairs of acquisitions performed with at least one of a plurality of mutually-different center wavelengths and a plurality of mutually-different states of polarization (SOP). For each said acquisitions, respective amplitudes of at least part of the repeated reflected light pulses are averaged so as to obtain an averaged reflected power. The PMD is obtained by, for each said pairs of said acquisitions, computing a value of a difference between the two averaged reflected powers corresponding to said pair, followed by the mean-square value of computed values of difference over said at least one of a plurality of mutually-different center wavelengths and a plurality of mutually-different states of polarizations (SOPs) and, from said mean-square value, calculating a value of the PMD for the optical fiber under test.

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There is provided a method and system of frequency dithered distributed acoustic sensing (FD-DAS) using group data signal processing, where the continuous wave (CW) coherent laser's optical frequency or optical phase for the FD-DAS interrogator may be set in evenly or randomly distributed manner for different data groups but they are kept as constant or with negligibly variation within each data group. Such FD-DAS may be used to improve acoustic or vibration signal measurement reliability, to allow to use a low-cost single-frequency laser such as a DFB laser, and/or to suppress polarization fading effect.

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A method for Over-The-Top (OTT) media service monitoring and testing including deploying multiple test agents throughout the network and orchestrating them together to create a single OTT media service delivery path with coherent measurement points. The method includes selecting and configuring all test agents forming an OTT media service delivery path in a network, wherein the test agents are deployed on devices in the network with pairs of agents in a client-server relationship; for each selected test agent, simulating a Hyper Text Transport Protocol (HTTP) Adaptive Streaming (HAS) media playback using a pair test agent as a HAS server; for each selected test agent, monitoring the HAS media playback via a Quality of Experience (QoE) model to collect metrics, influence factors, and QoE scores; and reporting collected metrics, influence factors and QoE scores, wherein the QoE scores are compared to isolate any performance degradation.

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There is provided an OTDR method and device for characterizing an optical fiber link. At least a first OTDR acquisition is performed toward the optical fiber link. From the at least one first OTDR acquisition, one or more events are identified along the optical fiber link and a value of at least one characteristic associated with each event is estimated. A second OTDR acquisition is performed toward the optical fiber link in order to target a specific event among the identified events. Values of one or more OTDR acquisition parameters for the second OTDR acquisition are determined such that the OTDR acquisition parameters comprise a second pulse width different from the first pulse width used in the first OTDR acquisition.

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