क्षण, Sanskrit for the precise instant.
An open-source simulator for PNT (positioning, navigation and timing) resilience.

Release v0.29.0 83 of 223 capabilities validated against independent external oracles About 96% line coverage, gated at 85% in continuous integration Licence: AGPL-3.0-only, or a commercial licence DOI 10.5281/zenodo.20528627

Rehearse the minute GNSS goes dark#

Kshana replays jamming, spoofing and clock holdover when GNSS (Global Navigation Satellite System) signals fail, and tells you how long a system keeps time and position inside its budget, and which clock or sensor buys the most margin. This is the WebAssembly package: the whole engine in JavaScript, in the browser or in Node.js. Every run is reproducible bit for bit from the scenario, the seed and the engine version.

Try it first with nothing to install: Kshana Studio runs the whole engine in your browser, compiled to WebAssembly, and uploads nothing.

Evidence#

83 of 223 capabilities validated against independent external oracles; 136 honestly labelled Modelled, 4 partner-owned. Each capability carries one label in a machine-checked ledger: VALIDATED (an independent external oracle agrees: real data, an independent implementation or published reference vectors), MODELLED (internally consistent, and said out loud) or PARTNER (a hardware partner owns it). Among the checks: all 666 SGP4 (Simplified General Perturbations 4) vectors of AIAA (American Institute of Aeronautics and Astronautics) 2006-6753 to 4.12 mm, and the Cowell force model to 0.08 m against Orekit 12.2.

Install#

npm install kshana

Usage#

The package is an ES (ECMAScript, standard JavaScript) module with a WebAssembly payload, built for the browser. Initialise it once, then call the engine synchronously. The only difference between the browser and Node.js is how the WebAssembly binary is loaded.

In the browser (through a bundler, or a page that serves node_modules/kshana/), init() fetches kshana_bg.wasm from beside the module:

import init, { run, summary, chart_svg, version } from "kshana";

await init();                                   // fetch and compile the WebAssembly binary

In Node.js, init() fails with TypeError: fetch failed (Node's fetch cannot read a local file), so read the binary from disk and hand it to initSync:

import { readFileSync } from "node:fs";
import { createRequire } from "node:module";
import { initSync, run, summary, chart_svg, version } from "kshana";

const wasmPath = createRequire(import.meta.url).resolve("kshana/kshana_bg.wasm");
initSync({ module: readFileSync(wasmPath) });      // compile the WebAssembly binary

Save the Node.js version as a .mjs file (or set "type": "module" in your package.json) so that import works. From there both are the same:

// A complete scenario, not a sketch: scenarios/clock-holdover.toml without its comment
// lines. It runs 2 h, 10 min of GNSS then about 1.8 h with GNSS denied, and asks how long
// a strontium optical clock and a chip-scale atomic clock (CSAC) each hold time to within
// 20 ns. sigma_y(1s) is a clock's Allan deviation at an averaging time of one second;
// q_wf, the white-frequency-noise intensity, is its square.
const toml = `
seed = 42
threshold_ns = 20.0

[time]
step_s = 10.0
duration_s = 7200.0

[gnss]
windows = [
  { t0 = 0.0,    t1 = 600.0,  state = "nominal" },
  { t0 = 600.0,  t1 = 7200.0, state = "denied" },
]

[clock_quantum]
id = "optical-sr-lattice"
provenance = "Strontium optical lattice clock, space-oriented goal sigma_y(1s)=1e-15 (Origlia/Schiller/Bongs et al., arXiv:1503.08457); q_wf=sigma_y(1s)^2; ground-demonstrator maturity, not flown; flicker/aging not modeled"
y0   = 5.0e-17
q_wf = 1.0e-30
q_rw = 0.0

[clock_classical]
id = "csac-sa45s"
provenance = "Microchip SA65 / SA.45s CSAC datasheet sigma_y(1s)=3e-10; q_wf=sigma_y(1s)^2; flicker/aging not modeled"
y0   = 5.0e-10
q_wf = 9.0e-20
q_rw = 0.0
`;

const result = JSON.parse(run(toml));           // the full result document
// timing_p95_ns: the 95th-percentile timing error over the GNSS outage, in nanoseconds
console.log(version(), result.classical.fom.timing_p95_ns);

console.log(summary(toml));                     // the one-line result string
const svg = chart_svg(toml);                    // the same chart the command-line interface (CLI) writes

On the WebAssembly face every entry point is a separate call: run (the result document as a JSON string), summary, chart_svg, table_csv (the scenario's CSV (comma-separated values) table as a string, or undefined for kinds that publish no table; it throws on an invalid scenario), run_all (one engine run returning {json, svg, summary, csv} as a JSON string — use it when you want more than one output, since every other call runs the scenario afresh), version, list_kinds / error_kind (introspection), encode_permalink / decode_permalink — the shareable-link (URL, uniform resource locator) codec Kshana Studio uses to round-trip a whole scenario through the address-bar fragment — and export_sp3 / export_omm / export_oem, the SP3-c (revision c of the Standard Product 3 format) and CCSDS (Consultative Committee for Space Data Systems) ephemeris artifacts — OMM, the Orbit Mean-elements Message, and OEM, the Orbit Ephemeris Message — the CLI writes. There is no one-call run_full here; that binding exists only on the Python wheel.

Every capability in the verification matrix is labelled validated (checked against an independent external oracle), modelled or partner-owned; optical-clock figures are space goals on ground hardware (no strontium optical clock has flown). Maturity is not uniform across domains — Earth PNT is validated against real data; deep-space and Mars navigation is modelled, with only its building blocks (light time, planet positions) validated against external oracles; real-mission deep-space OD (orbit determination) is on the roadmap.

Capabilities#

The engine has 75 scenario kinds; kshana kinds lists them with their fields.

• Spectrum: how a jammer takes the GNSS L band, band by band.
• Clocks and timing: holdover against a threshold, time transfer, and telecom holdover against the masks of the International Telecommunication Union's standardization sector (ITU-T).
• Constellations around any body: coverage, dilution of precision and availability around the Earth, the Moon or Mars, and the solar system at one epoch.
• Low-Earth-orbit navigation: signal, pass and link, navigation message, and a fused fix, stage by stage.
• Campaigns: a chained mission, a sweep or a Monte Carlo ensemble in one scenario.
• Reports, animation and exports: every figure with its unit and label; an animated drawing of a run; SP3 (Standard Product 3), CCSDS (Consultative Committee for Space Data Systems) orbit messages, CZML (Cesium Language), KML (Keyhole Markup Language), GeoJSON, STK (Systems Tool Kit) and SigMF (Signal Metadata Format) files.

Architecture#

The same scenario file gives the same bytes on every surface. MCP is the Model Context Protocol: kshana-mcp lets an AI (artificial intelligence) assistant run the engine.

Research#

Five papers on arXiv are built on the open engine, each with the command behind it: arXiv:2606.22054 (the optimism gap of interference detectors), arXiv:2606.24210 (a conditional timing protection level), arXiv:2607.05415 (how stable a PNT resilience score is), arXiv:2607.02566 (lunar surface station observability with very-long-baseline interferometry) and arXiv:2607.06212 (lunar south-polar geometry and surface beacons). See Research.

Editions#

The whole engine is free under the AGPL-3.0. Kshana Pro, a proprietary overlay that depends on the open engine and never forks it, and custom studies are available under contract from Ashforde OÜ: contact@ashforde.org. There are no prices; see docs/PRO.md.

Learn more#

• The full README → https://github.com/AshfordeOU/kshana
• Kshana Studio (the engine in your browser, as WebAssembly) → https://kshana.dev
• Capabilities → docs/CAPABILITY.md
• Validation and provenance → docs/VALIDATION.md · docs/PROVENANCE.md
• Verification matrix → docs/VERIFICATION-MATRIX.md
• Cite → CITATION.cff · DOI 10.5281/zenodo.20528627

Licence#

Free and open source under the GNU AGPL-3.0-only (the GNU Affero General Public License, version 3 only). A commercial licence is available from Ashforde OÜ (an Estonian private limited company; OÜ = osaühing) for closed integration; see LICENSING.md. Professionally developed and maintained by Ashforde OÜ.