A Quick Start Guide to Fiber-to-theAntenna (FTTA) Installation and Maintenance Testing Vol.
A Quick Start Guide to Fiber-to-the-Antenna (FTTA) Installation and Maintenance Testing Vol. 1 — Certifying Next Generation FTTA Cabling and Components Notice Every effort was made to ensure that the information in this document was accurate at the time of printing. However, information is subject to change without notice, and VIAVI reserves the right to provide an addendum to this document with information not available at the time that this document was created.
Table of Contents FTTA .......................................................................................................................................................................................................................4 Macrocell and Fiber Components .................................................................................................................................................................... 5 Inspect Before You Connect ...............................................
FTTA Staggering increases in bandwidth demand are forcing network operators to new models of mobile infrastructure like fiber-to-the-antenna (FTTA) to improve user experience and reduce costs. The performance of the cabling and components between the RRU (Radio remote Unit) and BBU (Base Band Unit) is key to delivering optimized system performance between the backhaul network and the end user. Network professionals must ensure network uptime and reliability while maximizing customer experience.
Macrocell and Fiber Components This guide will focus on macrocell fiber installation and maintenance tests. This type of network architecture generally involves RRU and BBU functions that are physically separated. The radio equipment is relocated next to their respective antennas in the RRU enclosures. Fiber is deployed using a remote fiber feeder cable (RFF) that interconnects the BBU located at ground level to a breakout box at the top. The fiber is then patched using a jumper into the RRU.
Connectors Fiber connectors enable fiber-to-fiber mating by aligning the two optical fibers. Fiber connectors come in various types and have different characteristics for use in different applications.
Simplex Fiber Core Cladding Ferrule Fiber endface view Body: Houses the ferrule that secures the fiber in place; utilizes a latch and key mechanism that aligns the fiber and prevents the rotation of ferrules of two mated connectors. Ferrule: Thin cylinder where the fiber is mounted and acts as the fiber alignment mechanism; the end of the fiber is located at the end of the ferrule which is referred to as the endface. The overall diameter of the ferrule depends on the relevant connector type.
Inspect Before You Connect Contamination is the #1 source of troubleshooting in optical networks! A single particle mated into the core of a fiber can cause significant back reflection (return loss), insertion loss, and equipment damage. Visual inspection is the only way to determine if fiber connectors are truly clean before mating them. The VIAVI SmartClass Fiber family is the next generation of optical handheld test solutions that let technicians inspect, test, certify, and save using a single device.
Fiber Attenuation Overview For any optical fiber link, we need to know the loss or attenuation of the cable or link to ensure it meets system requirements and is ready to survive network aging and environmental effects. As the light signal traverses a fiber, it decreases in power level. The decrease in power level is expressed in (dB) or as a rate of loss per unit distance (dB/Km).
Fiber Attenuation Overview Coupling loss Junction loss Impurities Input Output Absorption loss Injection Scattering loss loss Macro Bending loss Micro Bending loss Microbending occurs when the fiber core deviates from the axis. It can be caused by manufacturing defects, mechanical constraints during the fiber laying process, and environmental variations (temperature, humidly or pressure) during the fiber’s lifetime.
Inspect INSPECT Inspect Bulkhead 1. Select the appropriate bulkhead inspection tip that corresponds to the connector type and install on a probe. 2. Insert the probe into the bulkhead to inspect. 3. Determine whether the bulkhead is clean or dirty. yy If clean, do not touch it and CONNECT yy If dirty, CLEAN Inspect Patch Cord 1. Select the appropriate patch cord inspection tip that corresponds to the connector type and install on probe. 2. Attach the patch cord to the probe.
IS IT CLEAN Inspect: Is It Clean? Inspection Criteria Dirt is everywhere, and a typical dust particle (2 – 15 μm in diameter) can significantly affect signal performance and cause permanent damage to the fiber endface. Most field test failures can be attributed to dirty connectors, and most connectors are not inspected until the problem is detected, after permanent damage has already occurred.
IS IT CLEAN Inspect: Acceptance Criteria The tables below list the acceptance criteria standardized by the International Electrotechnical Commission (IEC) for single-mode and multimode connectors as documented in IEC 61300-3-35 Ed. 1.0. Single-Mode PC Connectors, RL ≥26 dB (Ref: Table 5) Zone Name Diameter Defects Scratches A. Core 0 – 25 μm 2 ≤3 μm none >3 μm none 2 ≤3 μm none >3 μm none B. Cladding 25 – 120 μm no limit <2 μm 5 from 2 – 5 μm none >5 μm no limit ≤3 μm none >3 μm C.
CLEAN Clean Clean Bulkhead with the IBC™ Guide cap cover Guide Cap Nozzle 1. Select the appropriate cleaning tool for the connector type. Nozzle extender lock Guide cap cover 2. Pull off the guide cap cover. Repeat steps 3, 4, and 5 if necessary. Dry Clean 3. Insert the cleaning tool into the bulkhead adapter and push the cleaner into the bulkhead two times (two clicks). For hard-to-reach places, push the nozzle extender lock and pull the nozzle out. 4. Determine whether clean or dirty.
CLEAN Clean Clean Patch Cord with the IBC™ Cleaner Guide cap cover Guide Cap Nozzle 1. Select the appropriate cleaning tool for the connector type. Nozzle extender lock Guide cap cover 2. Pull off the guide cap cover. Repeat steps 3, 4, and 5 if necessary. Dry Clean 3. Attach the cleaning tool to the connector and push the cleaner into the patch cord two times (two clicks). Impact 4. Determine whether clean or dirty.
CONNECT Connect There are three basic principles that are critical to achieving an efficient fiber optic connection: yy Perfect core alignment yy Physical contact yy Pristine connector interface Today’s connector design and production techniques have eliminated most of the challenges to achieving core alignment and physical contact. What remains challenging is maintaining a pristine endface. As a result, contamination is the #1 reason for troubleshooting optical networks.
TEST Test Fiber Continuity A visual fault locator (VFL) emits visible light to let technicians easily see light escaping from bends or breaks in the fiber. This is ideal for continuity checking and also to provide a means to identify the correct RFF fiber is routed to the correct RRU port. A VIAVI FFL-050 VFL detects bends, breaks, and fiber continuity.
TEST Test: Power Measurement Absolute Power Level Measurement Using a VIAVI Optical Power Meter The absolute power level (the system power measurement) is the amount of optical power present in the system, measured in dBm. The source of this power is the transmitter or transceiver sending information through the system.
TEST Test: Attenuation Measurement An insertion loss measurement for fiber acceptance test during onsite build is a non-destructive method and is used to measure the attenuation across a fiber, a passive element, or the entire optical link. This is often required where install phases do not have active equipment provisioning onsite or where cable infrastructure and equipment installs are performed by separate teams. Measure the output from the source fiber and a reference fiber directly.
TEST Test: Reference Power Measurement Reference Power Measurement (single-mode fiber) Using a VIAVI Optical Light Source 1. Inspect and, if necessary, clean both ends of the reference fiber jumper [J1]. 8. Power on the OLS and set the wavelength to Autolambda (1310 – 1550 nm). 2. Inspect and, if necessary, clean the OLS port. 9. Touch [SET REF] on the OLP to reference out the power level at 1310 – 1550 nm until 0.00 dB is displayed. 3. Connect J1 to the OLS port. 4.
TEST Test: Attenuation Measurement P Male patch cord B Female bulkhead inspection inspection Loopback Remote End (at Junction Box [JB] or RRU) 1. Inspect and, if necessary, clean both ends of the loopback device using the PCM port on the inspection microscope. 2. Inspect and, if necessary, clean the male end of fiber pair under test on the RFF or Jumper cable. Save images for report generation. Bulkhead At the RRU (tower structure or rooftop) 3.
TIER 1 Certification Report Qualification testing of the link throughout deployment and maintenance ensures problems are identified and resolved quickly. Proactive testing during key installation phases will help avoid turn-up delays and can significantly reduce the cost of deployment and maintenance.
VIAVI Essential Fiber Test Tools Visual Fault Locator The FFL-050 comes in a compact, ergonomic design for ultimate portability and can be used on 2.5 mm or 1.25 mm (optional) connector types. Fiber Probe Microscope The P5000i digital probe microscope provides automated connector Pass/ Fail analysis to certify compliance to customer specifications or industry standards, including IEC 61300-3-35.
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