Claude
6ac126e05c
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).
51 lines
2.0 KiB
Python
51 lines
2.0 KiB
Python
"""Quick inspection of the new high-amplitude events."""
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import os, re, sys
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sys.path.insert(0, ".")
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from analysis.load_bundle import _parse_txt
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from minimateplus.waveform_codec import walk_body, find_data_start
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ROOT = "decode-re/5-11-26"
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def main():
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for stem in ("M529LL1A.SP0", "M529LL1A.SS0", "M529LL1A.SV0"):
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bin_path = os.path.join(ROOT, stem)
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txt_path = bin_path + ".TXT"
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with open(bin_path, "rb") as f:
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raw = f.read()
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body = raw[43:-26]
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meta, samples = _parse_txt(txt_path)
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n = len(samples["Tran"])
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print(f"\n=== {stem} ===")
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print(f" file={len(raw)}, body={len(body)}, N_samples={n}")
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print(f" rectime={meta.get('Record Time')} pretrig={meta.get('Pre-trigger Length')}")
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print(f" PPV(T,V,L)={meta.get('Tran PPV')} / {meta.get('Vert PPV')} / {meta.get('Long PPV')}")
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# Show first few non-trivial samples
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print(f" First 5 truth samples (in/s):")
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for i in range(5):
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print(f" T={samples['Tran'][i]:8.3f} V={samples['Vert'][i]:8.3f} "
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f"L={samples['Long'][i]:8.3f} M={samples['MicL'][i]:8.3f}")
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# Peak sample positions
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for ch in ("Tran", "Vert", "Long"):
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vals = samples[ch]
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peak_i = max(range(n), key=lambda i: abs(vals[i]))
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print(f" {ch}: peak {vals[peak_i]:.3f} at sample {peak_i} (t={peak_i/1024:.3f}s)")
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# Body structure
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start = find_data_start(body)
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blocks = walk_body(body, start)
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types = {}
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for b in blocks:
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types[b.tag_hi] = types.get(b.tag_hi, 0) + 1
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print(f" body start={start}, total blocks walked: {len(blocks)}")
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print(f" block tag counts: {types}")
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# How far the walker got
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if blocks:
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last = blocks[-1]
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walked = last.offset + last.length
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print(f" walker stopped at offset {walked}/{len(body)} ({100*walked/len(body):.0f}%)")
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if __name__ == "__main__":
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main()
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