Terminology
| Term | Definition |
|---|---|
| TSL3 | Tersus proprietary sonar log file format used by the ES200 echo sounder and MarineBenchVue |
| BLH | Geodetic coordinates: B = latitude, L = longitude, H = ellipsoidal height |
| HGO | Height above Geoid (orthometric height) |
| RTK | Real-Time Kinematic — centimetre-level differential GNSS positioning |
| Draft | Vertical distance from the water surface to the transducer face |
| Sound Speed | Speed of sound through water, used to convert echo travel time to depth. Typical value: 1500 m/s |
| Tidal Correction | Adjustment to reduce measured depth to a common datum (e.g. chart datum) using tide gauge data |
| WGS84 | World Geodetic System 1984 — the global datum used by GPS |
| Transverse Mercator | A cylindrical map projection commonly used for UTM and national grids |
| UTM | Universal Transverse Mercator — worldwide projected coordinate system divided into 6° zones |
| Datum Shift | Transformation parameters to convert between different geodetic reference frames |
| Waterfall Display | Sonar visualization where each column represents one ping and rows represent depth bins |
| Bottom Line | The detected seafloor or riverbed return in the sonar waterfall |
| False Data | Sonar returns that do not represent the actual bottom — caused by fish, bubbles, or interference |
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