| Arc | One satellite signal followed while the satellite rises or sets through the elevation window over the water. One arc gives at most one water-distance result. |
| Azimuth sector | A range of compass directions (e.g. 120°–200°) pointing at the water; only satellites in the sectors are used. |
| BOOTSEL | The RP2350’s built-in bootloader mode: the unit appears as a USB drive named RP2350 and accepts a firmware file. |
| C/N0 (SNR) | Carrier-to-noise density ratio, in dB-Hz: the signal strength the receiver reports per satellite. Its oscillations carry the reflection. |
| Campaign | Experimental autonomous run started by a power-on, with automatic settings and a final satellite report. |
| Cloudloop | Ground Control’s platform that receives Iridium messages and forwards them to destinations. |
| Configuration | All settings stored on the unit; written only after the unit validates them; versioned. |
| Elevation window | The range of satellite elevations used: 5°–45° with the reflexa micro antenna (Campaign: fixed 5°–25°). |
| Field console | The BREVA reflexa micro desktop app (macOS, Windows, Linux). |
| Footprint | The water area that reflects the signals for the chosen sectors and elevations; drawn on the map. |
| Fresnel zone (first) | The ellipse on the surface where most of the reflected energy comes from, for one satellite position. |
| GNSS | Global Navigation Satellite Systems: GPS (USA), Galileo (EU), BeiDou (China), GLONASS (Russia), QZSS (Japan). |
| GNSS-IR | GNSS Interferometric Reflectometry: measuring a reflecting surface from the interference between direct and reflected signals in one antenna. |
| GPST | GPS Time, the unit’s clock; UTC + 18 s since 2017. The app shows UTC by default. |
| IMEI | The modem’s identifier; ties the unit to the Cloudloop account. |
| IMT | Iridium Messaging Transport, the message service of the RockBLOCK 9704. |
| Lomb–Scargle periodogram | Spectral analysis for unevenly sampled data; its peak gives the oscillation frequency and hence RH. |
| Map data pack | Optional global offline lake shorelines (HydroLAKES), installed from a USB stick or downloaded. |
| Normal / Advanced mode | The app’s two levels: installation and routine pages vs every setting and diagnostic. |
| Peak-to-noise (PNR) | Height of the periodogram peak relative to the noise; a quality indicator of an arc. |
| Record | One stored block of results (up to 10 arcs) in the unit’s queue. |
| Reflector height (RH) / water distance | Vertical distance from the antenna to the water. Water elevation = antenna elevation − RH. |
| RH search range | The range of heights the analysis looks for; Auto by default; the unit can move it and reports that it did. |
| Running buffer | Storage policy that overwrites the oldest results when full. |
| Session | A scheduled (or manual) period with the receiver on and arcs recorded. |
| Session estimate | The robust combination of the accepted arcs of a session, with its spread. |
| Status LEDs | Red, green and blue LEDs on the board that show the state without a computer. |
| Watchdog | A timer that resets the processor if the firmware stops making progress (internal 2 s; external ~60 s). |
