Scenario kind pagesEdit on GitHubSource: docs/kinds/by-kind/timetransfer.md

timetransfer (scenario kind)

Scenario kind of the engine v0.38.0, family Clocks, timing and holdover. Advisory: analysis output from a research and engineering tool, not type-approved navigation equipment and not a safety-of-life service. Every label here is the engine's or the verification matrix's; a kind is MODELLED unless the matrix says otherwise (how a label is earned: the README's Evidence section).

What it does#

Optical vs RF two-way time/frequency transfer.

One run of scenarios/timetransfer.toml summarises as: scenario 8f9c2e0e31a5 | optical sync_rms 0.98ps range_rms 0.293mm adev(1s) 1.73e-12 | RF sync_rms 1137.3ps range_rms 341.0mm adev(1s) 8.65e-10

Inputs#

From the schema (kshana kinds --json):

  • Required fields: seed, samples, step_s, range_spec_mm, link_quantum, link_classical
  • Optional fields: none

The example scenarios/timetransfer.toml sets, among others:

Field Value Unit
kind timetransfer text
link_classical.id twstft-rf text
link_classical.provenance Two-way satellite time and frequency transfer (TWSTFT, Ku-ba text
link_classical.q_rw_s 1.0000e-26 s
link_classical.sigma_j_s 5.0000e-10 s
link_quantum.id optical-isl text
link_quantum.provenance Optical inter-satellite link, picosecond-level synchronizati text
link_quantum.q_rw_s 1.0000e-32 s
link_quantum.sigma_j_s 1.0000e-12 s
range_spec_mm 10 mm
samples 600 not stated
seed 42 1

Run it#

kshana scenarios/timetransfer.toml

What it gives#

The scalar results of that run, with the units the engine states:

Result Value Unit
classical.fom.adev_tau0 8.6527e-10 1
classical.fom.range_p95_mm 636.83765 mm
classical.fom.range_rms_mm 340.957818 mm
classical.fom.sync_p95_ps 2124.261745 ps
classical.fom.sync_rms_ps 1137.312862 ps
classical.fom.within_spec_fraction 0.026667 1
classical.spec.id twstft-rf text
classical.spec.kind two-way-time-transfer text
classical.spec.params.q_rw 1.0000e-26 1/s
classical.spec.params.q_wf 0 s^2/s
The chart the engine writes for scenarios/timetransfer.toml, kind timetransfer

Evidence#

MODELLED: the verification matrix rows that name this kind.

The rows the run itself exercised, with the oracle the matrix gives each (the public sources are named there):

  • MODELLED Two-way/TWSTFT (Sagnac), GNSS common-view, PPP; link-jitter→range. Oracle (ExternalDataset): Sagnac magnitude checked against an authoritative PUBLISHED VALUE — N. Ashby, 'Relativity in the GPS', Living Reviews in Relativity 6:1 (2003), Eq. 1.29: an eastward equatorial circumnavigation accrues 207.4 ns (2ωA_E/c²); kshana reproduces 207.386 ns. Independently corroborated by RTKLIB 2.4.3 geodist() (Takasu, BSD-2-Clause), which carries the same 2Aω/c² geometry. The composite BIPM TWSTFT transponder/common-view/
  • MODELLED Deterministic, scenario-hashed, SBOM + cross-platform golden gates. Oracle (ExternalDataset): SBOM conformance to the official CycloneDX 1.5 JSON Schema (+ valid SPDX identifiers) — an external published standard, zero validation errors over the full dependency graph; the FoM-determinism / byte-reproducibility part remains a pinned self-consistency check, so the row stays MODELLED

Limitations#

What the run's own report says is not modelled or not validated:

  • Time-transfer error budgeting is MODELLED, not validated: a sub-claim is externally checked, but the whole capability composes modelled pieces, so the capability stays Modelled. (verification matrix (docs/MODELLED-RATIONALE.md))
  • Reproducibility & software assurance is MODELLED, not validated: a sub-claim is externally checked, but the whole capability composes modelled pieces, so the capability stays Modelled. (verification matrix (docs/MODELLED-RATIONALE.md))

See also#