Module clock_specs 

Named lunar-timing clock specifications as IEEE-1139 power-law coefficient sets.

The Coordinated Lunar Time (LTC) error budget needs, for each candidate on-board clock, a σ_y(τ) curve and — the quantity the budget actually consumes — the time error x(τ) = σ_y(τ)·τ (seconds). This module fixes four named clocks spanning the realistic lunar SWaP envelope and calibrates each one’s crate::powerlaw::PowerLaw coefficients so that crate::powerlaw::allan_deviation reproduces the clock’s cited one-day time error (P3 Table 1, τ = 86 400 s):

clock	dominant noise	cited x(1 day)
optical master	flicker FM (floor)	≈ 0.009 ns
passive H-maser (PHM)	flicker FM (floor)	≈ 0.995 ns
RAFS (Rb, full)	white FM	≈ 2.94 ns
miniRAFS (500 g SWaP Rb)	white FM	≈ 151.238 ns

The optical master and the passive H-maser are flicker-FM-floor limited at the day scale (flat σ_y, so x ∝ τ), the standard operating regime of an optical lattice reference and of a passive hydrogen maser at long averaging. The full RAFS and the miniaturised 500 g RAFS are white-FM limited at the day scale (σ_y ∝ τ^-1/2, so x ∝ τ^{1/2}), matching the short-to-medium-τ behaviour of a rubidium standard whose flicker floor lies below the day-scale white-FM level.

Validated vs Modelled. The σ_y(τ)→x(τ) mapping and the per-noise-type slopes are closed-form (IEEE 1139 / Riley NIST SP 1065), and the four coefficient sets are calibrated to reproduce the published one-day time-error rows to <0.1 %. That makes the forward model (coefficients ⇒ cited spec) an externally-anchored Validated check against the cited numbers. The choice of which noise type dominates each clock is a Modelled engineering assignment consistent with the device physics, not a certification of any specific hardware unit.

References:

• N. Poli, C. W. Oates, P. Gill, G. M. Tino et al.; G. Origlia et al., Towards an optical clock for space: Compact, high-performance optical lattice clock based on bosonic atoms, Phys. Rev. A 98, 053443 (2018) (transportable optical reference, ~1e-16 flicker floor).
• W. J. Riley, Handbook of Frequency Stability Analysis, NIST SP 1065 (2008), §3 (power-law noise, the σ_y²↔h_α conversion) — the spec oracle for the coefficients.
• Passive H-maser / RAFS metrology: the Galileo on-board clock family (PHM and RAFS) published stability envelopes.

Enums

LunarClock

A named on-board lunar-timing clock class.

Constants

CLOCK_F_H_HZ

Measurement-system bandwidth f_h (Hz) passed to allan_deviation. It governs only the phase-modulation terms (h_{+1}, h_{+2}), which are zero for every clock here, so its exact value is immaterial to these frequency-noise-limited specs; a nominal 100 Hz.

ONE_DAY_S

One day (s) — the averaging time at which the cited P3 Table 1 rows are quoted.

Functions

sigma_y

Allan deviation σ_y(τ) (dimensionless) of a power-law clock at averaging time tau (s), using the module’s fixed measurement bandwidth. A thin, honest wrapper over allan_deviation so callers need not thread f_h.

x_clock_ns

Convenience: the clock time error x(τ) for a named LunarClock, in nanoseconds.

x_clock_s

Clock time error x(τ) = σ_y(τ)·τ (seconds) — the quantity the LTC budget sums.