Workshop 5: Fiber optic measurements
Location: Bucharest, Grand Phenicia Hotel
Participants: 28 persons (Annex 1), from
AFOR
ANCOM – 2 persons
A standardization association: ASRO
7 members AFOR: Celesta, Prysmian, Romkatel, R&M Romania, Telecom Instruments, Teledatanet and Tele-Grup
5 telecom operators (RCS & RDS, Next-Gen, AKTA, Vodafone and Euroweb)
Electrica (2 persons from Bucharest and Muntenia Nord)
We mention that this workshop was the second AFOR event with live broadcast and the event can be watched on the AFOR Facebook page (4 hours and 2 minutes):
https://www.facebook.com/fibraopticaRomania/
The agenda of the workshop was the following one proposed:
9.00am: Introduction. Presentation of participants. Standards for FO measurements (AFOR)
9.15am: Fiber optic measurements, between the past, present and future. Each of the 5 dealers, AFOR members: Evolution of FO measuring equipment of the manufacturers it represents.
10.10: Presentations of equipment for optical fiber measurements.
11: coffee break
11.30: Q&A – part 1: answers to the AFOR questions by everyone:
1. Practical comparison between the measurements with the OTDR and with the powermeter. Which measurements best and most accurately express the quality of a fiber optic section and a fiber optic junction?
2. What kind of measurements do you recommend for FTTH networks? But for DWDM?
3. What are the tricks you consider important in understanding fiber optic measurements?
12.00: Q&A – part 2: questions from participants
12.45am: Conclusions
Summary
Terms met in fiber optic measurements:
or OSA = optical spectrum analyzer
o RFTS = Remote Fiber Test Systems
o OTDR = Optical Time Domain Reflectometer
o Powermeter = optical power measuring device
o VFL = Visual Fault Locator
o OFI = Optical Fiber Identifier
or CD = Chromatic Dispersion
or PMD = Polarization Mode Dispersion
o CWDM = Coarse Wavelength Division Multiplexing
o DWDM = Dense Wavelength Division Multiplexing
o MPO = Multi – Fiber Push-On (12 or 24 fiber optic connector)
o Dynamic range
o OTDR impulse width
o Acquisition time (measurement)
o Distance (English is Range)
o Ghost events
o Dead-zone = dead zone, can be event (reached 0.5 m) and attenuation (between 2 events)
o IOR – Index of Refraction
or BSC = Backscatter coefficient
o SOR = Standard OTDR Record, defined in the Telcordia SR-4731 standard
It was emphasized that the main way of evaluating the quality of the works of installation and junction of the optical fiber cables is the measurement of the installed optical fiber cables.
Optical fiber measurements are made not only with the OTDR, but also with many other instruments, depending on the application and the measurement parameters.
The first OTDR launched by Yokogawa appeared in 1981, by EXFO in 1982, and by MTS in 1983.
Models of optical fiber measuring devices were presented by the 5 equipment dealers, AFOR members, with the best optical fiber measuring devices in the world at the present time, as follows:
o Celesta: Yokogawa (OTDR, OSA) and NTest (RFTS)
o Romkatel: Anritsu, KingFisher
o Telecom Instruments: Viavi (formerly JDSU)
o Teledatanet: EXFO
o Teleprecision-MTS: AFL (American Fujikura Limited), Noyes
Trends noted and underlined in optical fiber measurements:
o Towards miniaturization of equipment
o The OTDR is replaced by SLM (Smart Link Mapper on Viavi for example or iOLM on Exfo – intelligent Optical Link Mapper) – the graphical representation of the path of a fiber optic path is replaced by a linear representation
o Automation of equipment using software (“fiberization”), which uses the cloud for both the documentation of measurements and the processes related to optical fiber measurements (AeRos at Rogue / AFL and Fiberizer at EXFO). Fiberizer is a free cloud solution that can be used by all interested technicians.
o Artificial Intelligence and Machine Learning is used in the analysis of fiber optic measurements (according to EXFO)
o Increasingly use of mobile phones / smartphones in the processes and works of measurements of fiber optic cables
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Working rules for fiber optic joints should be developed by each
A number of important aspects have been emphasized in fiber optic measurements:
o Evolution of measurements on fiber optic systems – from Dark Fiber to live fiber monitoring (active, with signal)
o Coherent OTDR – for underwater cables, with a dynamic range of 55 dB, for large lengths (approx. 200 km)
o Very important is the documentation of the works
o “Inspect before you connect” – LIVE
The iOLM Revolution
o Cleaning kits for fiber optic connectors are becoming increasingly important when working with faster technologies, such as DWDM
o For multimodal fiber optics, certification is done only with the powermeter, not with the OTDR
o Interoperability is ensured at the OTDRs through the SOR format, which is universal, standardized (Telcordia) and available to all OTDR providers
What problems affect optical fiber measurements in Romania?
o Less and less trained technicians
o Lack of knowledge of standards
o The impossibility of accreditation in Romania by RENAR of calibrating equipment (the need for a laboratory in Romania for calibrating measuring equipment, especially OTDR and powermeters)
Conclusions:
Contributions are requested for the improvement of the optical fiber measurement guide, drafted by AFOR in 2013, in the first version, which will have to be processed and improved by those who actually work – we are waiting for proposals to complete the guide until 31.01.2018 for the elaboration of version 2 of the guide.
Any other questions related to optical fiber measurements to which AFOR specialists can answer are expected.
