Adds docs/offset_investigation.md — a dated journal of the "offset" hardware
fault, in the style of the codec status docs: findings with provenance, dead
ends kept with the reason they died, and per-unit case files.
Contents:
- base rate 5-6 of 45 units (11-13%) over the DL2 archive, 2018-2026,
confirming rather than overturning the earlier 2-of-21 estimate
- the detector, with the rationale for each term and its known blind spot
(event traces carry real motion, so only trace-dominating offsets show)
- the bimodality result: relaxing the amplitude floor 11x adds no new units
- Instantel's own procedure and thresholds from their FAQs 13-0-21 / 12-0-10:
A/D-mode ">5 counts", the autozero key sequence, and the 2027-2069 X1/X8
acceptance window that explains the ~10% field success rate of a re-zero
- four ruled-out hypotheses, each with the evidence that killed it:
condensation, clipping, the sensor check as a predictor (102 offset events,
zero failures — a grossly offset unit passes its own self-check), and the
calibration-timing correlation (confounded, one unit per time bucket)
- open questions, chiefly whether SUB 0x0E carries the autozero numbers
Cross-referenced from CLAUDE.md and Appendix E of the protocol reference
(whose CRLF line endings are preserved).
Separately: CLAUDE.md had 793 NUL bytes appended after its last line. They
predate this work (present at least as far back as e42956a / v0.21.0) and made
grep treat the file as binary, silently skipping it. Stripped.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HgTe8CamXAHcAmaQ6QNcog
serversdownandClaude Opus 5
5f1ee5ba91