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✉ Send FeedbackFrequently asked questions
Quick answers about SOR / TRC file formats, how this analyzer works, and what to look for in your traces.
What is an SOR file?
SOR is the standard fiber-optic OTDR trace format defined by Bellcore SR-4731 (also published as IEC 61300-3-40). Virtually every commercial OTDR (Viavi, EXFO, AFL Noyes, Anritsu, Yokogawa, AQ7280, Tempo) saves trace files in SOR. A single SOR file contains the raw trace waveform, the OTDR's computed event table, and acquisition metadata (pulse width, wavelength, index of refraction, range, averaging time).
What is a TRC file?
TRC is EXFO's proprietary trace format (AppReg Format), produced by EXFO's FastReporter and FiberTrace software. It carries similar data to SOR but uses zlib-compressed property streams instead of a standardized binary layout. The analyzer reverse-engineers the parts of TRC needed for span length, total loss, and event-table reconstruction.
How do I open a SOR or TRC file online?
Drag and drop the file onto this page, or click the drop zone to browse. Parsing happens in your browser within a second. No upload, no account, no server. You'll see the fiber length, total loss, worst reflectance, an overall pass / fail verdict, and a full event table identifying every splice and connector along the span.
Does this upload my trace files anywhere?
No. The analyzer runs entirely as JavaScript in your browser. Files are read locally via the FileReader API, parsed in memory, and never transmitted. You can use this offline (after the page has loaded once) or behind a corporate firewall. No trace data leaves your network.
What's the difference between a splice and a connector in the event table?
The analyzer classifies events based on measurable back-reflection. Fusion splices are nearly reflectance-free because the two fibers fuse into one continuous glass column, so a loss step with no Fresnel spike is labeled splice. Connectors and mechanical splices have a glass-air-glass interface that always produces a measurable reflection, so those get labeled connector. The splice and connector loss thresholds are adjustable in the Pass / Fail panel.
What pulse width should I use for my fiber length?
Match pulse to span: ~10 ns under 3 km, 50–100 ns for 5–20 km, 200–500 ns for 20–60 km, 1 µs for 30–80 km, 3 µs for 80–130 km, and longer for very-long-haul. Too short a pulse loses the far end of the fiber in the noise floor; too long a pulse hides close events inside the dead zone. The analyzer automatically flags pulse / length mismatches after each analysis with a recommended pulse for your span.
Which OTDRs are supported?
Any OTDR that writes Bellcore SR-4731 / IEC 61300-3-40 (.sor) files works. That covers Viavi (formerly JDSU), EXFO, AFL Noyes, Anritsu, Yokogawa, AQ7280, Tempo, and most others on the market. EXFO's proprietary .trc format (FastReporter / FiberTrace exports) is also supported for span length, total loss, and event extraction.
Why don't the analyzed numbers exactly match my OTDR's display?
Small differences (typically 1 to 2%) come from index-of-refraction (IOR) calibration drift between the OTDR and the fiber under test. The analyzer reads each file's stored IOR rather than assuming a default value, which usually puts results within 1% of physical measurement. Larger discrepancies usually indicate a file from a format variant the parser doesn't yet recognize. Feel free to send a sample and we'll add support. For more on why OTDR numbers can disagree with an OLTS measurement of the same link, see our Fiber Testing Field Guide.