Show the innovation gate is blind to slow, correlated GNSS error (synthetic) #183

Parent

Follow-up to #131 and PR #180 (context only).

What to build

On Deep-Urban-1 the gate rejects none of the fixes while the mean NIS stays far below its level, and the receiver's fix errors are correlated over tens of seconds. The page labels the link between these as an interpretation. Build a seeded synthetic scenario with time-correlated GNSS multipath and show, with tests, whether the mean NIS stays low and the gate rejects nothing while the position error grows. The result is reported either way.

Acceptance criteria

• A seeded scenario with a stated correlation time and size, declared before the run.
• Rows report the rejection count with its Wilson interval, mean NIS against the gate level, and NEES, for an independent-error control and the correlated case.
• The overconfident single-anchor control row is kept.
• A short statement of what the result does and does not show, with no mechanism claim beyond the rows.

Blocked by

None (can start immediately).

RICE

Judgment estimates, not measurements. Same scales as contested-nav docs/prioritisation.md: Reach 1 to 10, Impact 0.25 to 3, Confidence 50, 80 or 100%, Effort in ideal working days.

Score = Reach x Impact x Audit boost x Confidence / Effort.