A one-page refresher. For full details, see user-guide.md.
d)tCal) — auto-filled from materialtEvent and First sensor (A or B)
| Tab | Output | Pro fields? |
|---|---|---|
| 2-Sensor | Distance along line | No (fully free) |
| 3-Sensor | X, Y on a surface | Yes |
| 3-Sen+ | X, Y with LSQ over 3 pairs | Yes |
| 4-Sensor | X, Y from two pairs (A–B + C–D) | Yes |
| 4-Sen+ | X, Y from 4 sensors, any position | Yes |
| 3D | X, Y, Z from 4 sensors | Yes |
| 3D+ | X, Y, Z from up to 6 sensors | Yes |
| Materials | Speed-of-sound picker | No |
| Help | Tutorials | No |
Settings is the ⚙ icon (top-right), not a tab.
Settings → Reference temperature, range -40 to +200 °C.
tCal fields across all tabsFeature-locked freemium ($19.99): - Free: 2-Sensor tab fully functional, no limits - Pro: Other tabs accessible but have gold-padlock fields that show paywall on tap
Pro unlocks: 3-Sensor through 3D+, custom materials, backup/restore, PDF reports, photo annotation.

Print result button on any result screen → PDF with header, inputs, result, visualization, photo (if taken), and temperature footer (when compensation active).
Customize header in Settings → Report header.
Backup: Settings → Backup → share to cloud/email.
Restore: Settings → Restore → pick backup file.
Same Google account (Android) or Apple ID (iOS) you bought with → Settings → Restore purchase → unlocks within seconds.
Auto-restore happens silently when you return to the app after redeeming a promo code externally.
tEvent sign / First sensor / sensor spacingdata-step — restart app if missingContact support@evdiag.net — include device model, app version (Settings → bottom), and a description of what you tried.