@ikaros-arch/gnss-core

The pure core of gnss-server: NMEA-0183 parsing and normalisation into a single Fix object carrying WGS84 lon/lat/height, ECEF XYZ, projected coordinates (default EPSG:32635, WGS84 / UTM 35N), 1-sigma accuracy and RTK status. No Node APIs, no I/O — it runs unchanged in a browser, a WebView or a native shell, so the same code that feeds gnss-server's WebSocket can turn a BLE or TCP receiver into fixes client-side. Only dependency: proj4.

npm install @ikaros-arch/gnss-core

Usage

import { FixAssembler, LineSplitter } from "@ikaros-arch/gnss-core";

const lines = new LineSplitter();                 // reassembles lines from chunks
const asm = new FixAssembler({
  antennaId: "RS4-rover",
  outputCrs: "EPSG:32635",
  transport: { remoteIp: "ble:AA:BB:CC", remotePort: 0 },
});

onChunk((chunk: string) => {                      // TCP segment, BLE notification, …
  for (const line of lines.push(chunk)) {
    const fix = asm.feed(line);                   // Fix on each GGA, null otherwise
    if (fix) render(fix);
  }
});

feed() remembers GST (measured sigmas), GSA (DOPs), RMC (date) and VTG (velocity) and folds them into the next GGA. Without GST the accuracy is estimated from HDOP/VDOP and flagged accuracy.source = "ESTIMATED".

Other CRSs: registerCrs("EPSG:25835", "+proj=utm +zone=35 +ellps=GRS80 …") before constructing the assembler. projectLonLat throws for an unregistered code.

API

| Export | Purpose | |---|---| | FixAssembler, FixAssemblerOptions | sentences in, Fix out (one receiver per instance) | | LineSplitter, DEFAULT_MAX_LINE_BYTES | chunk → complete lines, with overflow protection | | Fix | the wire schema — documented in gnss-server's docs/FRONTEND_INTEGRATION.md | | parseGGA, parseGST, parseGSA, parseRMC, parseVTG, verifyChecksum | individual sentence parsers (return null on bad checksum) | | llhToEcef, propagateSigmaToEcef, projectLonLat, registerCrs | geodesy |

Development

Lives in the packages/core workspace of gnss-server. From the repo root: npm test (vitest resolves the package from source), npm run build:core, npm publish -w packages/core --access public (builds via prepublishOnly).