2DC

PMS 2D-C, the classic 32-diode probe. The one-command driver decodes it end to end at stage 2 (the raw decode) and the Octave oracle covers the decode; v3.5's stage 4 runs it, checked against Octave on synthetic input.

The instrument, as the code sees it

Every row below is read from constants.IMGPROC_CONFIG, the port of imgProc_sm.m's own probe switch. None of it is typed into this page.

What runs today

Imported from the coverage matrix rather than restated, so this table and docs/developer/COVERAGE_MATRIX.md cannot disagree.

How to read this table.

• VALIDATED – the output was compared with an archived product the original code wrote, and every difference is accounted for.
• CROSS-CHECKED – the path runs, and its code is asserted against the original MATLAB/IDL executing under Octave/GDL – on fixtures, not necessarily on real data from this instrument.
• unvalidated – the path runs, but nothing independent has been compared with its output.
• refuses (by design) – the driver stops with a message, because the combination is meaningless or out of that engine's scope.
• refused (not built) – the driver stops with a message because the code for the combination has not been written; nothing known makes it impossible.
• REFUSES (DEFECT) – the driver stops with a message, but the combination should work and does not yet.
• untested – no test exercises this combination, so nothing is claimed either way.
• serial column – one process, the reference way to run.
• --chunks column – stage 3 (image processing) of each file split across N processes and merged.
• --jobs column – N raw files processed at once, one process each.
• --s2-jobs column – stage 2 (the raw decode) of one large file split across N processes.
• --jit column – stage 3's hottest per-particle kernels compiled with numba.
• arrayprobe_uiops – the UIOOPS v3.5 port, the default for new work.
• arrayprobe_soda2 – the SODA-2 port.

No shipped preset names this probe. A run needs a campaign preset declared in your own TOML ([run].presets), and [run].preset is required – it has no default.

Where a cell above reads refuses (by design) or REFUSES (DEFECT), the reason is in docs/developer/COVERAGE_MATRIX.md for that exact cell. A refusal here is always preferred to a silently wrong fast answer, and the two words are different: by design means the combination is meaningless, defect means it should work and does not yet.

Caveats

Consequences of this probe's own geometry

Computed from the table above, not recalled – each says which arithmetic produced it.

The 32-diode hollow scan covers this probe's whole array (32 diodes)

calculate_reject_unified.m:465 packs diodes 1-32 whatever the probe's width. On a 32-diode probe that is the entire array, so the truncation defect that bites the wider probes is a no-op here – and so, on this probe, is the wide_hollow_fix enhancement. Worth stating explicitly, because the caveat is real elsewhere in this package and does not transfer here.

Computed from: constants.IMGPROC_CONFIG['2DC'].diodenum = 32

The array images 0.8 mm, and a size ladder must respect that

32 diodes at 0.025 mm is 0.8 mm across. That is not a hard ceiling on recorded size, and it would be an overclaim to say so: a particle that merely has its centre in the array (sa_method 0) or is sized through the Heymsfield & Parrish reconstruction (sa_method 2) can be recorded LARGER than the array it crossed. The bound that survives is a factor, not an equality – a centre-in particle reaches about twice the array width, not twenty times it. So the honest reading is: a bin above roughly 1.6 mm on this probe is beyond what any sizing convention here produces, and a ladder whose top lies there is a configuration error rather than a sparse flight. The upstream finding that the default 2D-S bin table became the HVPS one (recorded in the review of the upstream code) is exactly that: a 30 mm ladder handed to a 1.28 mm array, 23x its width, and the symptom was a well-formed file with almost nothing in it.

Computed from: constants.IMGPROC_CONFIG['2DC']: diodenum 32 x ds 0.025 mm = 0.8 mm

Chunked stage 3: supported

Timing family pms is in CHUNKABLE_TIMINGS_V35, so --chunks splits stage 3 with no carried state and the result is byte-identical to a serial run.

Computed from: constants.IMGPROC_CONFIG['2DC'].timing = 'pms'; CHUNKABLE_TIMINGS_V35 = ('dmt', 'pms', 'fast2dc'); PRIMABLE_TIMINGS_V35 = ('spec',)

What a person knows and a constant does not

Curated in probe_caveats.json (in scripts/). Every citation is re-checked against the real file each time this page is generated.

The driver opens it, and stage 4 runs it

A PMS probe turns one raw file into THREE outputs at stage 2 (the raw decode), a shape neither the SPEC H/V-pair contract nor the DMT one-file contract covers. read_binary_PMS writes its three outputs under its own lowercase names, and the driver renames the one you asked for and publishes the other two beside it as unstamped siblings – the same shape the SEA reader already used. Stage 4 runs it: arrayprobe_uiops.sizedist lifted its refusal of probetypes 0 and 3 only after an Octave oracle bank existed for them – the oracle came first, as this project's order requires.

Source: src/arrayprobe/driver/run_flight.py

v3.5's stage 4 is checked against Octave on synthetic input only

The unmodified v3.5 sizeDist.m runs under Octave on synthetic twelve-particle inputs built so each probetype-0 branch changes a written number (record-start dead time, SEA-convention overload zeroing, the 2^24 clock rollback), and the port matches it variable for variable. The one real 2D-C file held (ACE-1, 1995) has not been run through this stage in a validated way, so that is layer 2 on synthetic data, not a claim about a campaign. With iaThreshType 2 the MATLAB dies on int_arr2 (preserved; the port raises).

Source: src/arrayprobe_uiops/sizedist.py

Reject code 't' is never emitted, on any probe

calculate_reject_unified.m:269 rejects on the tighter threshold (max_comp_img_ar) before :272 tests the looser one (max_edge_img_ar), so the second branch is unreachable and image_auto_reject never contains 116. The netCDF Description attribute at imgProc_sm.m:325-329 states the two thresholds the other way round. Both are preserved verbatim – this is a faithfully reproduced upstream defect, not a port bug. If you are tabulating reject codes, 't' is structurally absent rather than merely rare.

Trust the .call sidecar, not the filename

Every stage stamps its configuration into a .call sidecar and refuses an input that disagrees or carries no stamp. If you write products with your own script instead of arrayprobe run, you inherit this problem.

Ratios this probe appears in

None. No ratio measured so far has this probe on either side – which follows from the data held: a ratio needs two chains over the same raw, and there is no raw here to run two chains over.

Where to go next

Generated, not hand-maintained, from arrayprobe.constants.IMGPROC_CONFIG, coverage_matrix.build_matrix() and the curated caveats in probe_caveats.json.