The BW filename encodes only the serial NUMBER — `<letter><3 digits>` where
letter = chr(ord('B') + serial // 1000), so `L895…` decodes to 10895. The
two-letter family prefix is not in the filename at all, and every offset
scanner synthesized it as f"BE{num}".
Four of the 43 archive units are BA, not BE. Their binaries say so plainly:
BA9229, BA10060, BA10895, BA15957. Brian caught BA10895 by recognising that
no such unit as BE10895 exists.
serial_of() now reads the serial string out of the file body and falls back
to the old synthesis only when no matching string is found. No analysis
changes: grouping was by the numeric part, which was always correct, and no
unit number maps to more than one serial (checked across all 43).
The same assumption is live in two production sites and is NOT touched here,
because fixing ingest renames rows a running store and Terra-View already
reads them:
- sfm/waveform_store.py:870 `return f"BE{serial_num}"` on import
- minimateplus/client.py:2538 `raw_data.find(b"BE")` in the monitor-log
partial-record decode, which yields serial=None on a BA unit
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HgTe8CamXAHcAmaQ6QNcog
Brian's method, and better than v2's whole-record median: the pre-trigger
window is definitionally quiet (the buffer captured before the trigger fired),
whereas a median is merely robust to the event. Requiring the floor to hold
across pre-trigger / middle / end rejects transients that a median cannot.
per channel: pre/mid/end medians, spread = max - min
offset when |pre| >= floor AND spread <= 0.02 in/s
real fault >= 3 consecutive flagged events on that channel
The empirical noise floor justifies the threshold and validates the decoder:
across 19,244 non-flagged channel-events the pre-trigger floor is 62.7% exactly
0.000, 94.5% within +/-1 quantisation unit, median +0.0000, mean -0.0008. There
is no systematic zero-point bias — an independent confirmation of the
32000-count geo scale.
The result is threshold-insensitive across a 2x range (0.020 to 0.040 in/s),
which is what separates a real signal from a tuned one:
FINAL: 5 of 45 units (11%) — BE9558, BE11529, BE12599, BE13117, BE18438
BE11007 and BE10895 drop out; the spread test identifies them as transients
rather than pedestals. v1's 11% headline was right by luck — it included
BE11007 and named the wrong channel on most units.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HgTe8CamXAHcAmaQ6QNcog
serversdownandClaude Opus 5