SOR to PDF

What this converter does

An OTDR writes its measurement to a .sor file — a binary record that Windows, macOS and phones cannot open, and that normally needs the licensed software that came with the instrument. This page reads the file and lays it out as a PDF you can email to a client, attach to an acceptance pack or file with the as-built documentation.

• Drop up to 20 traces at once and download them individually or as a ZIP.
• Every figure comes from the file as the instrument stored it. The raw trace is not re-analysed, so the losses and reflectances match what the OTDR reported in the field.
• Nothing is kept. Traces are converted in memory and deleted immediately — no account, no upload history.

What is in the PDF report

Measurement summary	Wavelength, pulse width, acquisition range, averaging time, span length, total link loss, optical return loss, event count, fibre type
Acquisition & instrument	Make, model and serial numbers, optical module, software version, group index, backscatter coefficient, sample resolution, number of samples and averages, loss and reflectance thresholds
Trace	The full acquisition range, plus the same trace with the vertical axis expanded so the backscatter slope stays readable next to a saturating reflection. Events are marked and numbered
Event table	Distance, event type, the raw Telcordia descriptor, insertion loss, reflectance and section slope for every event the instrument detected

What is a .sor file?

SOR stands for Standard OTDR Record. It is the interchange format for optical time-domain reflectometer measurements, defined by Telcordia SR-4731 — the successor to Bellcore GR-196-CORE. Every major OTDR manufacturer can write it, which is why it is what you get when you export a trace for someone else to read.

Inside, the file is a set of labelled binary blocks: a map of the blocks themselves, general parameters (cable and fibre identifiers, locations, wavelength), supplier parameters (the instrument that took the measurement), fixed parameters (pulse width, group index, sample spacing, averaging), the key-event table the instrument's analysis produced, and finally the data points — often tens of thousands of samples, each one a backscatter level at a known distance along the fibre.

That structure is why a .sor file cannot simply be renamed or opened in a text editor, and why a screenshot of the instrument display is a poor substitute: the event table, the thresholds the analysis used and the acquisition settings are all part of the record, and a reviewer needs them to judge whether the measurement supports the result.

Questions

Is it free?

Yes, and there is no account. Fair-use limits apply: 20 files per batch, 8 MB per file.

Are my traces stored or looked at?

No. The file is parsed, the PDF is built, and both are discarded when the download finishes. The server keeps only a request count and the requesting IP address, for usage statistics and to stop abuse — no filenames and no measurement data.

Which OTDRs does it work with?

Any instrument that writes a standard single-trace .sor file — Viavi/JDSU, EXFO, Anritsu, Yokogawa, Fluke Networks, INNO, and others. It has been tested most heavily against Viavi MTS files (SR-4731 versions 1 and 2). Vendor-specific blocks are left alone; the standard blocks are what the report is built from.

Why does my file come back as unreadable?

The two usual causes are multi-trace files and vendor-only formats. Multi-wavelength or multi-fibre records that pack several traces into one file are rejected rather than half-read — export the traces separately and convert them one at a time. Proprietary formats such as EXFO .trc are not SOR files at all, even though they hold the same kind of measurement; export to .sor from the vendor software first.

Can I convert a whole folder of traces?

Select them all and use Download all as ZIP; each trace becomes its own PDF, and any file that cannot be read is listed in skipped.txt inside the ZIP instead of silently disappearing.

Does the report change any of the numbers?

No. Distances, insertion losses, reflectances and section slopes are reproduced exactly as stored. Negative insertion losses are left as they are — an apparent gain is a real artefact of splicing fibres with different backscatter coefficients, not an error to be tidied away. The only interpretation added is the vertical reference for the plot, which is the lowest recorded sample of the trace.

Bidirectional measurements?

Convert each direction separately. If the file name contains _tx or _rx, the direction is picked up and printed in the report header.

Last updated 2026-08-18