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feature:coverage

Computes RF coverage in-process with org.meshtastic:kp1812, an implementation of Recommendation ITU-R P.1812, over Mapterhorn terrain. It works offline once the terrain is cached.

Where it runs

Every map host runs the same flow. Each caller below passes this module's rememberCoverageEstimate() to feature:map's SitePlannerHost as its estimate. SitePlannerHost shows the form, runs the estimate behind a progress dialog, and hands the resulting GeoJSON back so the host can add it as a map layer and move the map to the transmitter.

Host Caller
Android, Google flavor MapView
Android, F-Droid flavor SitePlannerSlot
Desktop DesktopSitePlannerSlot

Shape

SitePlannerParams -> Site + ElevationSource -> LocalCoverage.sweepGrid() -> CoverageGrid -> toGeoJson(CoverageStyle)
                                                       |
                                                       +-- org.meshtastic:kp1812 (ITU-R P.1812)

The model, the ElevationSource seam, and the GeoJSON export live in commonMain. The platform source sets hold only the terrain cache location (coverageTerrainDirectory()) and, in jvmMain, the java.awt demo renderer CoverageDemo. Terrain is cached through feature:map-terrain's TerrainTileStore under terrain/coverage in the app's storage (~/.meshtastic/terrain/coverage on Desktop), apart from downloaded offline map regions. ElevationSource is a single suspend method: the app backs it with Mapterhorn tiles, and tests back it with a lambda, so the suite needs no network, WebView, or terrain download.

P.1812 is a different model from the hosted planner's SPLAT! ITM, so predictions don't match it pixel for pixel.

Tests

The tests are behavioral. kp1812 checks the model against the ITU reference itself, so these check that this module drives it correctly:

  • Signal decays with distance over flat ground.
  • A 400 m ridge shadows what's behind it.
  • More transmit power reaches at least as far.
  • reachable agrees with the receiver sensitivity.
  • Every bearing contributes equally to the sweep.
  • The geodesy round-trips.
  • The polar sweep resamples onto a grid without moving the prediction.
  • Every palette the planner offers resolves, and transparency maps to opacity.
  • The terrain zoom drops for a wide disc, so its tiles fit the cache.
  • A canceled terrain fetch restarts for a caller that is still waiting.

Run them with ./gradlew :feature:coverage:allTests. ./gradlew :feature:coverage:coverageDemo runs a real prediction against Mapterhorn terrain and writes a PNG and the GeoJSON; pass its arguments with -PdemoArgs="...".