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FAQ

Common questions about files, offline use, accuracy, and privacy.

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Common quick fixes

A .sor trace file won't open, or distances look wrong

The OTDR tab reads industry-standard Telcordia SR-4731 .sor files. If a file misbehaves:

Confirm the file extension is .sor (exports renamed to .pdf or .csv by OTDR software will not parse).
Open it via the Load SOR file button so the iOS file picker grants the app access.
If the span length looks off, type the known fiber range into the Range field — the trace and all event distances recalibrate instantly.
Still wrong? Email us the file and the expected length — vendor-specific .sor quirks are exactly the bug reports we want.

A calculator result looks wrong

Nine times out of ten it is a unit or reference mismatch:

Check dB vs dBm — relative vs absolute power are different inputs.
Check GBd vs Gb/s — symbol rate and bit rate differ by the bits-per-symbol factor.
OSNR values assume the 0.1 nm reference bandwidth unless the tool's hint says otherwise.
Load one of the tool's presets — if the preset result matches its label, the formula is healthy and the inputs need a second look.

If you still believe a value is wrong, email the tool name and your inputs. Every formula is sourced from public ITU-T/IEEE standards and textbooks, and we correct fast when something slips.

Text is too small, or I want a different look

Open the Settings tab. You can change the accent theme, the font, the font weight, and the text size independently. Reset theme, font & size restores the defaults in one tap.

I want to start completely fresh

Settings tab → Clear all data & reset app. This removes your favorites and restores default appearance instantly. Calculators and reference data are built in and unaffected.

Frequently asked questions

Is the app really free?

Yes — all 47 calculators, all 59 reference tables, the glossary, alarm and spec databases, and the OTDR reader. No in-app purchases, no subscriptions, no ads.

Does it work offline?

Completely. Every feature works in airplane mode. The app makes no network requests at all.

Where does my data go?

Nowhere. Settings and favorites stay on your device; .sor files are parsed locally and never uploaded. See the privacy policy — it is one page because there is nothing to disclose.

Which file types can it open?

OTDR trace files in the Telcordia SR-4731 .sor format — the standard export of EXFO, VIAVI, Anritsu, Yokogawa, and most other OTDRs.

Does it run on iPad?

Yes, iPhone and iPad, iOS/iPadOS 17 or later.

Where do the formulas and values come from?

Public ITU-T recommendations (G.652–G.657, G.694.1, G.696.1, G.97x), IEEE standards, and established fiber-optics texts. Each tool's hint line names the relationship it implements, and results distinguish pass/fail thresholds from engineering margins.