Three things to make pickup smoother:
1. analysis/README.md (NEW): catalogues the ~25 scratch scripts.
Categorizes them as "still useful" / "superseded — keep for
archaeology" / "pure exploration". Tells a fresh engineer which
files to read first and which to ignore.
2. scratch/next_experiment_skeleton.py (NEW): stub + spec for the
segment-channel scoring analyzer. Includes the fixture loader,
block walker, and decode-segment-as-channel helper — just enough
scaffolding that the next pass starts from "fill in
score_segment_against_all_channels()" rather than from scratch.
Already runs and confirms 13 segments per 3-sec event with sample
starts going to 6590 (way past the 3328 actual samples) — strong
evidence that not all segments carry Tran.
3. Removed decode-re/ duplicate. It was a mirror of tests/fixtures/.
Analysis scripts that hardcoded decode-re/ paths updated to point
at tests/fixtures/. CLAUDE.md note updated: future event uploads
go directly into a dated subdirectory under tests/fixtures/.
All 40 tests still pass. Skeleton runs.
User uploaded 3 high-amplitude events (PPV 6-7 in/s — shook the geophone
hard) to decode-re/5-11-26/. These cracked the Tran codec:
- Preamble bytes [3:5] and [5:7] = Tran[0] and Tran[1] as int16 BE
in 16-count units (LSB = 0.005 in/s). Confirmed across all 7
fixtures.
- First data block carries Tran deltas from sample 2 onward:
* 10 NN block: NN/2 bytes of payload, each byte = two 4-bit signed
nibble deltas (high nibble first)
* 20 NN block: NN int8 signed deltas
Verified 22+42+46 = 110 Tran samples across SP0/SS0/SV0 with 0 errors
against BW's ASCII export.
Why the earlier 96-combination brute force failed: the quiet 5-8
events all had T[0] = T[1] ≈ 0 so the preamble's per-channel encoding
was undetectable. Loud events made the encoding obvious.
What's solved:
- minimateplus.waveform_codec.decode_tran_initial: returns first
N Tran samples in 16-count units for any body.
- Walker length formula for in-data 30 NN blocks (NN*2 instead of NN*4).
- Walker now handles bodies that start with 20 NN (in addition to 10 NN).
What's still open:
- Tran past the first data block (multi-block channel switching).
- Vert / Long / MicL channel encodings.
- Walker correctness past offset ~427 in event-b.
Tests: 36 pass. decode_waveform_v2 still returns None — the full
multi-channel decoder is not wired up. decode_tran_initial is the
new verified entry point.
Files: minimateplus/waveform_codec.py, tests/test_waveform_codec.py
(adds 5-11-26 fixtures + decode_tran_initial tests), and
docs/instantel_protocol_reference.md §7.6.1 (Tran codec spec).
Claude