Phase 1 Plan: Foundation and Encoding (Gateways 0-3)
Scope
- Gateway 0: architecture and environment readiness
- Gateway 1: spreading code generation
- Gateway 2: message encoding (BCH, LDPC, CRC, interleaving)
- Gateway 3: navigation frame assembly and validation
Objectives
- Establish deterministic architecture for algorithmic and DSP-heavy implementation.
- Deliver reproducible PRN code generation and encoded message artifacts.
- Prove framing correctness before signal synthesis work begins.
Why This Phase Is First
- Code generation and encoding define every downstream artifact; defects here propagate into decoding and interoperability.
- Performance and correctness in later gateways depend on deterministic primitives and table-backed constants established now.
Workstreams
- Architecture and table integration
- PRN code generation correctness
- FEC and CRC encoding path
- Frame construction and timing validation
- Test vectors and benchmark baselines
Week-by-Week Plan
Weeks 1-2 (Gateway 0)
- Engineer A
- Freeze architecture boundaries between code generation, encoding, signal, decoding, and parsing.
- Approve ADRs for language/runtime and deterministic processing strategy.
- Engineer B
- Define validation thresholds for correctness and runtime budgets.
- Engineer C
- Define interoperability artifact schema and weekly exchange operating flow.
- Developer A
- Build code-generation module scaffolding and parameter-loader interfaces.
- Developer B
- Build frame/encoding module scaffolding and stable data model types.
- Developer C
- Build CI jobs for table-validation, tests, and benchmark capture.
Exit criteria:
- Architecture baseline approved and traceable.
- Spec-table ingestion passes schema checks.
- CI executes deterministic baseline tests.
Weeks 3-4 (Gateway 1)
- Engineer A + Developer A
- Implement Gold, Weil primary, secondary, and tertiary code generation paths.
- Validate PRN outputs against Annex and spec-table references.
- Engineer B + Developer C
- Implement code-family test matrix for PRN 1-210 and selected edge checks.
- Add code-generation runtime benchmark capture.
- Engineer C + Developer B
- Generate interoperability-ready code artifacts with metadata and checksums.
Exit criteria:
- Reference-match correctness at required PRNs.
- Deterministic regeneration of identical code artifacts.
- Runtime metrics collected and published.
Weeks 5-6 (Gateway 2)
- Engineer A + Developer A
- Implement BCH path for Subframe 1 and CRC-24 path for longer subframes.
- Integrate LDPC BG2 settings for SB2/SB3/SB4 paths.
- Engineer B + Developer C
- Build unit and negative tests for BCH/CRC/LDPC/interleaver boundaries.
- Validate encoded length and filler/bit-layout compliance.
- Engineer C + Developer B
- Produce encoded-vector package format for cross-team decode checks.
Exit criteria:
- Encoding outputs match expected dimensions and constraints.
- Error-detection behavior validated under malformed input injections.
- Encoded vectors reproducible in clean environment.
Weeks 7-8 (Gateway 3)
- Engineer A + Developer B
- Assemble 12-second frame with sync, SB1, SB2, SB3, and SB4 structures.
- Validate Table 14 constants and subframe layouts.
- Engineer B + Developer C
- Validate frame structural integrity and timing-field consistency.
- Add frame-level regression and property checks.
- Engineer C + Developer A
- Build partner-facing frame artifact exports and decode expectations.
Exit criteria:
- Frame structure conforms to timing and layout constraints.
- Sync pattern and subframe segmentation validated.
- Frame artifacts are exchange-ready and replayable.
Risks and Mitigations
- Risk: table-integration drift
- Mitigation: strict schema validation and table-hash checks in CI.
- Risk: framing off-by-one defects
- Mitigation: explicit bit-offset tests from
sb2_bit_layout.csv and frame-constant checks.
Phase 1 Definition of Success
- Gateways 0-3 complete with evidence-backed artifacts.
- Encoding and frame outputs are deterministic, valid, and exchange-ready.
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