💡 WireXpert Fiber Optic Testing

Section 1: Fiber Fundamentals & Test Tiers

Fiber carries data as light, so it's immune to electromagnetic interference and reaches much farther than copper. Certifying it means proving the light gets through with an acceptable loss.

Test tiers (TIA-568.3)

The WireXpert MP fiber modules are Tier 1 certifiers: FM (multimode, 850/1300 nm), FS (singlemode, 1310/1550 nm), and FQ (both). Tier 2 needs a separate OTDR.

Fiber types

Test wavelengths: 850 and 1300 nm for multimode, 1310 and 1550 nm for singlemode. OM3 and OM4 are optimized for 850 nm VCSEL lasers, the light sources used in 10 Gb/s and faster transceivers.

Section 2: Connectors, Cords & Clean End-Faces

Connectors

The MP FQ's test ports accept SC/PC and LC/PC adapters, which are included. FC/PC and ST/PC adapters are optional.

Test reference cords and launch conditions

• Test reference cords (TRCs) are high-quality cords used only for testing. Their connectors must match the link's connectors. Cord kits are ordered separately from the tester.
• Encircled flux (EF) controls how light fills a multimode core, so different testers get the same loss result. TIA-568.3 and IEC 61280-4-1 call for an EF-compliant launch on multimode. The MP FQ's 850 nm multimode source is EF compliant out of the box.

Inspect → clean → inspect

1. Inspect every end-face with a fiber microscope or inspection probe before mating it.
2. Clean it if it's dirty, using a one-click cleaner or a dry or lightly IPA-wetted lint-free wipe in a single direction.
3. Inspect again. Never mate a connector you haven't inspected. One dirty end-face contaminates the face it's plugged into.

IEC 61300-3-35 grades end-faces by zone. The core zone must be free of scratches and defects. The surrounding cladding zone allows only a limited number of small defects. An automatic inspection probe applies the criteria for you.

Section 3: Reference Methods

The reference sets the 0 dB starting point. The method you choose decides which connections end up in the measured loss.

1-jumper dual-ended reference on the MP

1. Choose Test Settings › Reference › 1-jumper, then set the cable (or Generic MMF/SMF) and the test limit.
2. Inspect and clean the TRCs. Connect TX1 and RX1 between the LOCAL and REMOTE units as the screen shows, then run Tools › Set Reference.
3. Check the reading: −5.35 to +4 dBm for singlemode, or −25.35 to −15 dBm for multimode.
4. With TRC Verification on, move the cords to a coupler with the second set of TRCs and confirm the same ranges.

Section 4: Tier 1 Testing with the WireXpert MP

Loss budget (TIA-568.3 allocations)

Notice that the connectors dominate on short links. Each extra mated pair adds 0.75 dB of budget, and dirty connectors eat it fast.

Dual-ended AUTOTEST

1. Cord connections: TX1 to the LOCAL TX port, RX1 to the REMOTE RX port, TX2 to the REMOTE TX port, and RX2 to the LOCAL RX port. Connect the free ends to fiber 1 and fiber 2 of the link.
2. Under Test Settings › OLT Method, choose uni-directional or bi-directional.
3. Press AUTOTEST. In bi-directional mode, a Step 2 prompt has you swap the TX and RX connectors at the near end, then at the far end, then continue.
4. Review the loss and margin at each wavelength and save the result under the link label.

TIA-568.3 accepts Tier 1 loss measured in one direction at each wavelength. Many project specifications and warranty programs ask for bi-directional results, so check before you start. The MP measures length up to 12 km on multimode and 130 km on singlemode.

Section 5: Tier 2: OTDR Concepts

An OTDR (optical time domain reflectometer) sends pulses down the fiber and reads the light scattered and reflected back. The trace shows where each connector, splice, and bend is, and how much loss each one adds. The WireXpert MP doesn't include an OTDR. These are the concepts you need when a project calls for Tier 2.

Key settings

• Launch cord: moves the first connector past the OTDR's dead zone so it can be measured. A receive cord at the far end lets the last connector be measured.
• Pulse width: narrow pulses separate closely spaced events; wide pulses reach farther.
• Dead zones: right after a reflective event, the OTDR can't see the next event (event dead zone) or measure its loss (attenuation dead zone).
• IOR (index of refraction): converts time to distance. Standard singlemode is about 1.468 (light travels at about 68% of its speed in a vacuum). A wrong IOR makes every distance wrong, but it doesn't change loss.
• Both directions: test from each end and average, to cancel gainers and get true splice loss.

Section 6: VFL, Polarity, Reports & Troubleshooting

Visual fault locator (VFL)

The MP FQ includes a 650 nm red VFL, rated laser Class II below 1 mW, with inputs for 1.25 mm and 2.5 mm ferrules.

• Continuity: red light at the far end means the fiber is continuous.
• Breaks and bends: red glow leaking through a jacket or a connector boot marks the spot.
• Polarity: trace which strand lights up at the far end.

Polarity

Transmit has to reach receive. TIA-568.3 defines polarity Methods A, B, and C for array (MPO) systems, and A-to-B polarity for duplex patching. A polarity error can pass a loss test, because light still gets through, just on the wrong fiber. So verify polarity separately with the VFL or the tester's results.

Reports

Save every result under its link label. Create PDF or CSV reports on the tester or in Softing's eXport PC software, and share them with the ITN Sync app. Include the limit, the reference method, the TRC details, the tester serial number, and the calibration date.

Common failures

Final Assessment

Answer all 10 questions. You need 80% (8 of 10) to pass. These questions are different from the section knowledge checks. Enter your name and email below the questions, then submit.