The segment-channel scoring analyzer (from scratch/next_experiment_skeleton.py)
ran and immediately confirmed the rotation hypothesis:
SP0 seg 0: best fit Vert 508/508 ✓
SP0 seg 1: best fit Long 508/508 ✓
SP0 seg 3: best fit Tran 508/508 ✓ (Tran continuation)
SP0 seg 5: best fit Long 508/508 ✓
SP0 seg 9: best fit Long 508/508 ✓
V70 seg 0: best fit Vert 508/508 ✓
V70 seg 1: best fit Long 508/508 ✓
Channels rotate Tran → Vert → Long → MicL per 40 02 segment header.
Also discovered the segment header has DOUBLE duty: bytes [14:18] anchor
the NEW segment's channel (2 samples as int16 BE in 16-count units), AND
bytes [0:4] extend the PREVIOUS channel by 2 more samples (2 deltas as
int16 BE). This is the same "2 anchors + delta stream" structure as the
body preamble for Tran.
decode_waveform_v2 now returns full per-channel sample dicts.
Byte-exact verified ranges:
V70: Tran 512, Vert 512, Long 512 (all first segments)
JQ0: Tran 512, Vert 258
SP0: Long 1536 (all 3 L segments)
Still open: the 30 NN block format (high-amplitude packed deltas) —
appears mid-segment when single-byte deltas can't carry the magnitude.
6 new tests bring the count to 46. All passing.
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Categorizes them as "still useful" / "superseded — keep for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.
Investigated multi-segment Tran continuation but couldn't crack it.
Each hypothesis tried (segment header consumes 0/1/2 T deltas, blocks
continue Tran with various interpretations) breaks at sample ~512.
Block budget for V70 segment 1: 264 nibbles + 244 RLE zeros = 508
deltas — exactly the segment size. So the block structure CAN encode
508 single-channel samples, but applying segment 1 blocks as Tran
gives wrong values.
Most likely the channel ordering changes in segment 1+ (e.g., segment
0 = Tran, segment 1 = Vert, segment 2 = Long, etc.) but I couldn't
verify cleanly. Stopping here — segment-0 Tran decode is solid and
multi-segment work needs more fresh thinking.
User uploaded a Vert-heavy event (JQ0) and a Mic-heavy event (V70).
Those two were exactly what was needed to crack the next piece:
- 00 NN block = run-length-encoded zero deltas in the current channel.
Append NN copies of the current cumulative value (no change).
- find_data_start now recognizes 00 NN as a valid first tag (some events
begin with a leading 00 NN RLE block).
- decode_tran_initial now decodes the FULL segment 0 (not just the first
data block).
Results across 5 fixture events:
- M529LL1A.SP0 (loud-all-channels) : 510 / 510 ✓
- M529LL1L.JQ0 (Vert-heavy) : 510 / 510 ✓
- M529LL1L.V70 (Mic-heavy) : 510 / 510 ✓
- M529LL1A.SV0 (loud-from-start) : 58 / 58 ✓
- M529LL1A.SS0 (loud-from-start) : 42 / 502 (stops at first 30 04)
The 30 04 block (only seen in loud-from-start events) hasn't been
decoded yet — likely a channel-switch marker for the high-amplitude
regime.
Also discovered: segment header (40 02) payload bytes [0:2] = T_delta
at first sample of new segment, [6:8] = byte length to next segment.
Multi-segment Tran decoding still diverges after sample 512 because
the per-segment channel ordering after the header is unknown.
Tests: 40 pass (up from 36).
Files:
- minimateplus/waveform_codec.py: find_data_start fix, RLE handling,
full segment-0 decode in decode_tran_initial
- tests/test_waveform_codec.py: synthetic RLE test, full segment 0
tests for JQ0 and V70
- tests/fixtures/5-11-26/: M529LL1L.JQ0, M529LL1L.V70 + TXT exports
- docs/instantel_protocol_reference.md §7.6.1: RLE + segment-header docs
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).
Decoded the structural framing of the Blastware waveform body — the bytes
between the 21-byte STRT record and the 26-byte file footer. The body is
a sequence of tagged variable-length blocks, NOT raw int16 LE. Five tag
types (10/20/00/30/40 NN) and their lengths are now confirmed against the
4-event May 2026 fixture bundle. Body splits cleanly into ~16 segments
(for a 1280-sample event) separated by 40 02 segment headers carrying a
monotonically incrementing uint32 LE counter at bytes [8:12].
What's done:
- minimateplus/waveform_codec.py — block walker, segment splitter, segment
header parser. decode_waveform_v2 is a stub returning None until the
byte-to-sample mapping is solved; client.py is unchanged.
- tests/test_waveform_codec.py — 31 tests covering block detection, lengths,
contiguous-walk, segment splitting, segment-header parsing, and counter
monotonicity. All pass.
- tests/fixtures/decode-re-5-8-26/ — bundled fixtures (4 events, BW binary
+ Blastware ASCII export each).
- docs/instantel_protocol_reference.md §7.6.1 — replaced retraction box
with the verified structural decoding plus an explicit list of what's
still open.
What's still open: the per-byte mapping inside 10 NN / 20 NN blocks. 96
channel-permutation × nibble-order × sign-convention combinations were
brute-force tested; none match BW's ASCII export to within ±1 ADC count.
The codec is more elaborate than uniform 4-bit deltas — likely a hybrid
variable-bit-width scheme with segment-anchor resync points. Next
recommended step: capture an event with a known calibration tone to pin
down magnitude scaling.
Walker also bails out partway through event-b (open issue documented in
both the module and the protocol reference).
Claude