feat(nvsim): propagation.rs material attenuation [nvsim:pass3]
Pass 3 of the implementation plan. Adds per-material attenuation along
sensor–source line-of-sight segments. Free-space 1/r³ falloff stays in
source.rs (it's part of the dipole formula); this layer applies the
*additional* attenuation when LoS crosses material slabs.
Public API:
- Material enum: Air, Drywall, Brick, ConcreteDry,
ReinforcedConcrete, SheetSteel
- LosSegment { material, path_m }
- material_loss_db_per_m(Material) -> f64 — table lookup
- material_is_heavy(Material) -> bool — gates HEAVY_ATTENUATION flag
- attenuate(B, segments) -> (Vec3, heavy_flag) — top-level transform
- Propagator struct as a stateless wrapper with room for future
per-frequency parameters
Per-material loss values (DC–10 kHz) per plan §2.2:
- Air / Drywall / Brick: 0 dB/m (drywall + brick conjectural; no
systematic primary source for residential-wall magnetic-field
penetration loss at RuView geometry — gap flagged in plan §6.3)
- ConcreteDry: 0.5 dB/m (Ulrich NDT&E Int. 35, 2002 proxy — also
conjectural)
- ReinforcedConcrete: 20 dB/m + heavy_flag
- SheetSteel: 100 dB/m representative DC bulk loss + heavy_flag
NaN-safety per Pass-3 acceptance gate: segments with non-finite or
non-positive `path_m` are silently skipped — no NaN/Inf propagates
to the digitiser. Asserted in
test_nan_or_negative_path_is_skipped_without_nan_in_output.
7 new tests:
- free_space_is_identity_transform
- drywall_is_approximately_zero_db
- dry_concrete_attenuates_at_half_db_per_meter
(1 dB total = 10^(-1/20) ≈ 0.8913 linear)
- reinforced_concrete_attenuates_and_raises_heavy_flag
(4 dB total = 10^(-0.2) ≈ 0.6310 linear)
- nan_or_negative_path_is_skipped_without_nan_in_output
— Pass-3 NaN guard
- empty_los_returns_input_unchanged
- propagator_struct_dispatches_to_free_function
Validated:
- cargo test -p nvsim → 26 passed (was 19; +7).
- cargo test --workspace --no-default-features → 1,601 passed,
0 failed, 8 ignored (was 1,594; +7).
- ESP32-S3 on COM7 streaming live CSI (cb #200, recent reboot).
Co-Authored-By: claude-flow <ruv@ruv.net>
8c062fbaa4