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rUv
4072455d1e
Physics scrutiny of WiFi-band maritime sensing scenarios. Steel skin depth is 3.25 um at 2.4 GHz, making bulkheads utterly opaque. Saltwater attenuation is 853 dB/m. The 'through-bulkhead WiFi radar' framing common in conservation/maritime is wrong; the actual feasible category is 'through-seam' sensing exploiting slot diffraction through gaskets, hatch seals, and vent grilles. Composite link budget for 7 maritime scenarios (ESP32-S3 121 dB budget, 10 dB SNR margin): FEASIBLE: - Man-overboard surface @ 200 m: +25 dB - Cabin door, 2 mm seam: +31 dB - Cabin door, 5 mm seam: +39 dB - Container, 30 mm vent slot: +45 dB IMPOSSIBLE: - Closed 10 mm steel door: -938 dB - Submarine pressure hull: -929 dB - Head 30 cm underwater: -231 dB Five feasible verticals catalogued: man-overboard surface, through-seam crew vitals, container tamper detection, hatch-seal predictive maintenance, engine-room thermal anomaly via condensation. Composes with prior threads: - R6 Fresnel envelope + slot diffraction = narrower composite envelope - R10 link-budget primitives reused unmodified for air-side maritime - R7 multi-link consistency essential against superstructure jammers - R14 privacy framework transfers directly to crew-cabin monitoring Honest scope: best-case ignores vessel vibration (5-30 Hz, in-band with R10 gait frequencies), engine ignition noise, salt-spray, steel-surface multipath. Maritime gait-classification is harder than land. The romantic 'through-hull radar' is now explicitly debunked. The actual product roadmap is gasket-leakage sensing, surface detection, and predictive-maintenance audits. Coordination: ticks/tick-10.md, no PROGRESS.md edit.
108 lines
3.5 KiB
JSON
108 lines
3.5 KiB
JSON
{
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"model": "skin-depth steel + lossy-dielectric saltwater + slot-diffraction seam",
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"materials": {
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"2.4_GHz": {
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"steel_skin_depth_um": 3.248736671806984,
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"steel_atten_dB_per_mm": 2673.654677948628,
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"saltwater_atten_dB_per_m": 852.7792439147287
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},
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"5.0_GHz": {
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"steel_skin_depth_um": 2.2507907903927653,
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"steel_atten_dB_per_mm": 3859.0881200843564,
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"saltwater_atten_dB_per_m": 867.7495416795573
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}
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},
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"scenarios": [
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{
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"scenario": "man-overboard, surface-floating",
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"freq_ghz": 2.4,
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"fspl_db": 86.07916660695635,
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"bulk_loss_db": 0.0,
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"seam_loss_db": 999.0,
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"metal_path_used": "bulk",
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"metal_path_loss_db": 0.0,
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"saltwater_loss_db": 0.0,
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"total_loss_db": 86.07916660695635,
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"esp32_link_budget_db": 121,
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"snr_margin_db": 24.92083339304365
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},
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{
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"scenario": "man-overboard, head 30 cm underwater",
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"freq_ghz": 2.4,
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"fspl_db": 86.07916660695635,
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"bulk_loss_db": 0.0,
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"seam_loss_db": 999.0,
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"metal_path_used": "bulk",
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"metal_path_loss_db": 0.0,
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"saltwater_loss_db": 255.83377317441858,
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"total_loss_db": 341.9129397813749,
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"esp32_link_budget_db": 121,
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"snr_margin_db": -230.91293978137492
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},
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{
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"scenario": "crew vitals through 10 mm steel cabin door (closed)",
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"freq_ghz": 2.4,
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"fspl_db": 49.88145871091758,
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"bulk_loss_db": 26736.546779486278,
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"seam_loss_db": 999.0,
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"metal_path_used": "seam",
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"metal_path_loss_db": 999.0,
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"saltwater_loss_db": 0.0,
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"total_loss_db": 1048.8814587109175,
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"esp32_link_budget_db": 121,
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"snr_margin_db": -937.8814587109175
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},
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{
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"scenario": "crew vitals through cabin door (2 mm seam gap)",
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"freq_ghz": 2.4,
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"fspl_db": 49.88145871091758,
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"bulk_loss_db": 26736.546779486278,
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"seam_loss_db": 29.891207909453847,
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"metal_path_used": "seam",
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"metal_path_loss_db": 29.891207909453847,
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"saltwater_loss_db": 0.0,
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"total_loss_db": 79.77266662037142,
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"esp32_link_budget_db": 121,
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"snr_margin_db": 31.227333379628575
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},
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{
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"scenario": "crew vitals through cabin door (5 mm seam gap)",
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"freq_ghz": 2.4,
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"fspl_db": 49.88145871091758,
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"bulk_loss_db": 26736.546779486278,
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"seam_loss_db": 21.93240773601309,
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"metal_path_used": "seam",
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"metal_path_loss_db": 21.93240773601309,
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"saltwater_loss_db": 0.0,
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"total_loss_db": 71.81386644693066,
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"esp32_link_budget_db": 121,
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"snr_margin_db": 39.18613355306934
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},
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{
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"scenario": "container intrusion (steel cargo container, 2 mm walls, 30 mm vent slot)",
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"freq_ghz": 2.4,
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"fspl_db": 60.14065230988498,
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"bulk_loss_db": 5347.309355897256,
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"seam_loss_db": 6.369382728340219,
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"metal_path_used": "seam",
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"metal_path_loss_db": 6.369382728340219,
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"saltwater_loss_db": 0.0,
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"total_loss_db": 66.5100350382252,
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"esp32_link_budget_db": 121,
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"snr_margin_db": 44.4899649617748
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},
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{
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"scenario": "through hull (submarine, 30 mm pressure hull)",
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"freq_ghz": 2.4,
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"fspl_db": 40.88207853739662,
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"bulk_loss_db": 80209.64033845883,
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"seam_loss_db": 999.0,
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"metal_path_used": "seam",
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"metal_path_loss_db": 999.0,
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"saltwater_loss_db": 0.0,
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"total_loss_db": 1039.8820785373966,
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"esp32_link_budget_db": 121,
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"snr_margin_db": -928.8820785373966
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}
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]
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} |