This product is typically interfaced with solutions dealing with inventory or quality control, with the management systems of active transmission equipment, or any network management system designed to provide access to optical test resources for PON or point-to-point networks. The product is a stand-alone, intelligent solution capable of mapping a line and producing structured and documented data (XML format) of all measurable elements using best-in-class OTDR technology. The elements discovered on the transport fiber are tested against pass/fail criteria, with loss/reflectance and distance values included in the same structured data. Reflective filters can also be used during testing to position and assess the quality of each branch beyond the splitter(s).
Measurement of End-to-End Loss (EEL)
A key function of the Node iOLM is its ability to measure end-to-end loss or optical attenuation between the OTDR’s location, in this case the central office, and any connector port downstream—even when a port is beyond a series of splitters. By simply splicing or inserting a high-reflectance demarcation (HRD) filter, and using a mobile access tool, a field technician or supervisor can confirm the key information and values below:
- Connectivity confirmation–proper upstream connectivity
- Loss in absolute dBs–delta of the measured loss and the expected or typical loss at this point
- Optical fiber length–correlation with network documentation
Transport (F1) Fiber Discovery and Diagnosis
By simply using a generic configuration (e.g., single stage 1 x 32 split), the Node iOLM discovers all elements connected downstream: TAMs or WDMs, patch panel connectors, cross-connects, splice points and a first-stage splitter. It measures their optical parameters, mainly their position from the test access module (WDM or coupler), and the induced loss and reflectance, if any. It applies pass/fail thresholds and provides an at-a-glance analysis to quickly determine whether or not the transport fiber meets the specifications and if the connectivity corresponds to the as-planned documentation. This baseline is then used for fault discovery in the troubleshooting phase.
HRD Detection, Measurement and Management
The Node iOLM offers a full set of test functions designed to confirm the presence of a newly inserted HRD, measure it and manage its lifecycle.
F1, F2 and F3 Fault Isolation and Location
By acquiring multipulse OTDR traces and comparing them to their respective baselines, the Node iOLM can detect, isolate and locate degradations on demand, or automatically, when at least one HRD has failed. If multiple HRDs are present on the P2MP line, they will first be used to isolate faults before or beyond upstream splitters. The Node iOLM uses multi-HRD analysis to detect small line degradations, which is typically not possible through active/PON equipment network management because of its very high dynamic range and attenuation resolution, which is required for proactive network surveillance.
The accuracy of the fault-finding algorithm has been greatly enhanced compared to other OTDR test methods thanks to EXFO's 2-lambda test method, which uses 1650 nm for HRD testing and 1625 nm (or any other out-of-band wavelength) for RBS fault-finding. Given the nature of the Fiber Bragg grating (FBG) filters used, all signals except 1650 nm will pass transparently through. This enables standard Rayleigh backscattering testing at 1625 nm without the dead zones created by the strong reflectance at the FBG filters’ central wavelength (1650 nm).
As a general rule, the accuracy of the PON (P2MP) fault location function is a few meters on transport/F1 and from a few meters to 100 m on the distribution, depending on fiber impairment, type and topology.
Special Diagnosis on Optical Lines and Elements
Specific analysis and reports are generated and can be read directly from the test result data. Actions may be recommended to the technician for the entire line being tested or for a specific element considered as failed. An example of this is when an overlapping situation occurs after adding a new HRD to the line; the Node iOLM will provide hints on how to resolve the issue. It should be noted that a conflict status will be created if one HRD is added at less than 50 cm optical distance from a filter that is already present and detected on the line.
High-Reflectance Demarcation Filters
Two models are available: pigtail and adapter. In both cases, the filters have to be inserted in the proper direction in order to measure attenuation. Pigtails are bare fiber on the network side (upstream). HRD is in an SC connector, inside ferrule, on the customer side. For plug type or adapter type, the male side connects toward the ONT/terminal. On request, HRDs are also available in a field-assembly connector type.