Add Label H2 AMDAR Meteorological decoder plugin

[thepacket]

Adds a decoder for AMDAR (Aircraft Meteorological Data Relay) waypoint reports on label H2 — a stream of 28-char position+altitude+temperature+wind records terminated by G.

Record format

N 60230 E 008174 3528 M 552 125 021 G

Handles leading fragment detection (multi-part transmissions). Coordinates: DDMMT (degrees+minutes+tenths), altitude in tens of feet, temperature in tenths of °C with P/M sign, wind direction + speed.

Coexists with existing Label_H2_02E.

npm run build passes.

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📥 Commits

Reviewing files that changed from the base of the PR and between 10f9f69 and 5dd533f.

📒 Files selected for processing (3)

• lib/MessageDecoder.ts
• lib/plugins/Label_H2_AMDAR.ts
• lib/plugins/official.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[kevinelliott]

Summary

Adds Label_H2_AMDAR for label H2 AMDAR (Aircraft Meteorological Data Relay) waypoint reports — a stream of 28-char position+altitude+temperature+wind records terminated by G. Registered last in MessageDecoder.ts/official.ts. Coexists with the existing Label_H2_02E. No companion test file.

Verdict

Comment-only review — the per-record decoding looks careful and correct. Two structural concerns: missing tests, and a missing preamble qualifier that makes coexistence with Label_H2_02E work only because of how 02E's internal validation happens to fail-soft. Please address before merge.

Must Fix

• Add a Label_H2_AMDAR.test.ts. No tests at all today. At minimum: qualifiers() shape, a multi-record happy path (2–3 records), the leading-fragment branch (0G... prefix), the no-records bail, and a non-matching string.

• Coexistence with Label_H2_02E is fragile. AMDAR declares qualifiers: { labels: ['H2'] } with no preambles, so it runs against every H2 message. The dispatcher tries H2_02E first (registered earlier, line 59 vs your line 81), and H2_02E only succeeds when the message starts with '02E' and the trailing chunk is 'Q'. For an 02E-prefixed message that doesn't satisfy parts[parts.length - 1] !== 'Q', H2_02E returns decoded: false and the dispatcher falls through to AMDAR. AMDAR's own firstRec regex won't match an 02E-shaped weather report, so it bails — but that's silent, not deliberate.

  Two cleaner options:

  1. Add preambles: ['N', 'S', '0G', '1G', /* etc, the leading-frag patterns you actually observe */] so the dispatcher can short-circuit.
  2. Or front-validate explicitly: if text.startsWith('02E'), return decoded: false early without running the regex.

  Option 1 is cheaper; option 2 is more defensive. Either is fine — please pick one and add a test confirming AMDAR does not claim a 02E-prefixed message.

Should Fix

• text.replace(/\s+/g, '') strips ALL whitespace before parsing. That works for the documented format, but if a multi-part transmission concatenates two records without their separating space, you'd already be fine; if a record contains an embedded space-separated subfield in some real-world variant, you'd silently fold it in. Consider replacing only the documented inter-field spaces explicitly, or document this as a deliberate normalization step.
• HHMMSS / temperature validation gap. Wind direction up to 360°, wind speed unbounded, temperature unbounded — the regex enforces digits but not ranges. wind direction = 999 will be reported verbatim. Reject on windDir > 360, windSpd > 999 (or whatever the documented max is) to surface clearly malformed records.
• ResultFormatter.temperature(decodeResult, String(first.temperatureC)) — the formatter expects M/P prefixes for sign ('M55.2'), not a raw signed decimal ('-55.2'). Read result_formatter.ts:331 — the implementation does Number(value.replace('M','-').replace('P','+')). For '-55.2', neither replace fires, Number('-55.2') returns -55.2, so it happens to work — but that's a coincidence, not the contract. Either pass it as M55.2/P55.2 to align with the formatter's intent, or store directly via raw.outside_air_temperature and skip the formatter for this field.
• Anchor data is the first record only. The headline position/altitude/temperature come from records[0], but for a multi-record AMDAR transmission the last (most recent) sample is usually the more useful headline. Worth a comment explaining the choice or switching to records[records.length - 1].
• raw.leading_fragment = fragment || undefined; — fine, but the formatted item is only pushed when fragment is non-empty. Make sure the test for the no-fragment case asserts the absence of the code: 'FRAG' row.
• Item codes REC1, REC2, … — using a per-record code/type that varies (record_${idx}) makes programmatic filtering harder than a stable type: 'amdar_record', code: 'REC', value: ... pattern. Consumers that index by type will see N distinct types per message.

Nits

• text.search(/\.../) returns -1 for no match. Your firstRec > 0 check handles > 0 and < 0 but not === 0 (perfectly aligned, no fragment) — that's fine because body = text is already correct and fragment = '' from initialization. Tests should still cover both branches.
• The doc-comment ASCII art is excellent.
• Math.round(lat * 1e5) / 1e5 to 5 decimals (~1m precision) is reasonable for AMDAR.

Tests

None added. Please add Label_H2_AMDAR.test.ts. See "Must Fix" for coverage.

Notes — Registration & Coexistence

• Registration order: Label_H2_02E is at line 59, Label_H2_AMDAR at line 81. So 02E gets first crack at every H2 message — correct, given AMDAR has no preamble qualifier and would otherwise grab everything.
• Coexistence: Today AMDAR doesn't actually claim 02E-prefixed messages because its firstRec regex won't match that shape. Works in practice; please make it explicit (see "Must Fix" #2).
• Preambles: None set on AMDAR. Recommended to add — see above.

Thanks @thepacket! The numeric decoding (DDMMT coords, tens-of-feet altitude, signed-tenths-of-degrees temp) reads cleanly and is well-documented.