research(R11): maritime sensing — through-bulkhead impossible, through-seam works (#712)
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.
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# R11 — Maritime sensing: through-bulkhead RF is impossible, through-seam works
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**Status:** physics scrutiny + honest verdict + 10-20y vertical map · **2026-05-22**
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## TL;DR
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The romantic "through-bulkhead WiFi sensing for ships and submarines" framing is **physically wrong** at WiFi bands. Steel bulkheads have a skin depth of **3.25 µm at 2.4 GHz** — a single millimetre of mild steel produces 2,674 dB attenuation, more than the link budget of any portable device by a factor of 10²². No amount of clever DSP recovers a signal through closed metal.
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What **does** work is **through-seam** sensing — exploiting the diffraction leakage through gaskets, vent slots, hatch seals, and porthole gaskets. This thread maps which maritime scenarios are physically feasible and which aren't.
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## Physics
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### Skin depth in steel
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```
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δ = 1 / √(π·f·μ·σ)
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```
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For mild steel (σ = 1·10⁷ S/m, μ_r = 1):
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| Frequency | Skin depth | Per-mm attenuation |
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|---|---:|---:|
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| 2.4 GHz | **3.25 µm** | **2,674 dB/mm** |
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| 5.0 GHz | 2.25 µm | 3,859 dB/mm |
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A 1 mm steel sheet attenuates 2,674 dB at 2.4 GHz — utterly impassable.
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### Saltwater attenuation
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For seawater (σ = 4.8 S/m, ε_r = 81) via the lossy-dielectric model:
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| Frequency | Attenuation |
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|---|---:|
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| 2.4 GHz | **852.8 dB/m** |
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| 5.0 GHz | 867.7 dB/m |
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Saltwater is similarly opaque. A head 30 cm underwater = 256 dB additional loss = invisible. Submarine RF comms work at VLF (10-30 kHz) for exactly this reason; WiFi-band underwater detection is hopeless.
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### Slot diffraction (the loophole)
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For a narrow slot of width `w << λ` in an otherwise opaque conductor, the diffraction loss approximates:
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```
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L_slot ≈ 20·log10(λ / 2w) when w < λ/2
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≈ 0 when w ≥ λ/2
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```
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At 2.4 GHz λ = 12.5 cm, so any slot wider than 6.25 cm is effectively transparent. A typical cabin-door gasket gap is 2-5 mm — significant attenuation (~22-30 dB) but well within link budget.
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## Composite scenarios
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`examples/research-sota/r11_maritime_propagation.py` computes the composite (FSPL + bulk + slot + saltwater) for seven scenarios. ESP32-S3 link budget = 121 dB, 10 dB SNR margin reserved for DSP.
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| Scenario | Path used | Total loss | SNR margin | Verdict |
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|---|---|---:|---:|---:|
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| Man-overboard, surface-floating @ 200 m | air | 86 dB | **+25 dB** | ✅ feasible |
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| Man-overboard, head 30 cm underwater | air→water | 342 dB | -231 dB | ❌ impossible |
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| Crew vitals through 10 mm closed steel door | bulk steel | 1,049 dB | -938 dB | ❌ impossible |
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| Crew vitals through cabin door, 2 mm seam | seam | 80 dB | **+31 dB** | ✅ feasible |
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| Crew vitals through cabin door, 5 mm seam | seam | 72 dB | **+39 dB** | ✅ feasible |
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| Container intrusion (30 mm vent slot) | seam | 67 dB | **+45 dB** | ✅ feasible |
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| Through submarine pressure hull (30 mm steel) | bulk steel | 1,040 dB | -929 dB | ❌ impossible |
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## Verticals catalogued
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### ✅ Feasible at WiFi bands
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1. **Man-overboard surface detection.** ESP32 + omnidirectional antenna on a ship's mast, monitoring CSI on a beacon worn by crew. Pull-down of the beacon below the waterline → CSI signature flips from "surface scatterer with sea-state Doppler" to "no signal" within 1 second. False-positive rejection via gait-frequency-band check (R10) on the surface-state CSI.
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2. **Through-seam vitals in confined spaces.** Submarine berth compartments, ship cabins, lifeboat interiors. Sensor in adjacent compartment monitors heart-rate / breathing via 2-5 mm gasket leakage. Use case: **lone-watch monitoring** without crew compromise (no camera, no microphone).
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3. **Container intrusion / contents change.** Sea-cargo container with at least one vent slot >2 cm leaks RF. Sensor outside monitors CSI signature; sudden change indicates contents shifted or door opened. Use case: tamper detection on bonded customs cargo, long-haul container security.
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4. **Hatch-seal integrity audit.** A known-position transmitter inside a compartment, receiver outside. Closed-and-sealed hatch → only seam leakage (specific dB attenuation per gasket condition). Drift in this attenuation over time = gasket degradation. **Predictive maintenance** for watertight integrity.
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5. **Engine room thermal-anomaly detection (via condensation).** RF propagation in moist air is bandwidth-dependent. Sustained CSI-amplitude drift = condensation envelope shifting = thermal anomaly. Indirect, but adds a sensing modality to engine rooms without IR cameras.
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### ❌ Not feasible at WiFi bands
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1. Through-hull submarine comms (use VLF/ELF instead — different industry).
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2. Underwater swimmer detection (use sonar / acoustic — different industry).
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3. Through-watertight-bulkhead sensing into a sealed compartment with no leakage path.
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4. Through-radome of any reasonable thickness (most radomes are thin enough to pass — but this isn't the use case).
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### Re-framed verticals (with caveats)
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1. **Pirate-skiff approach detection (10y).** Air-link sensing from a vessel's superstructure can detect small boats approaching at radar-blind low altitudes. Range: ~100 m at 2.4 GHz (R10's foliage-less air model). The maritime version of R10's wildlife sensing.
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2. **Crew situational awareness in dark / smoke (15y).** Through-seam vitals + breathing patterns inside compartments tell fire-control whether occupants are conscious. Real value-add when smoke obstructs cameras.
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3. **Whale-strike avoidance (20y).** Surface-floating mammals can be detected at the surface by CSI Doppler signature; the practical issue is **range** (whales are slow, ship is fast — need 200+ m detection). The R6 Fresnel envelope at 200 m link length is ~3.5 m wide; large enough to catch a whale-sized target, marginal for smaller mammals.
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## How this composes with prior threads
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- **R6** (Fresnel forward model): the per-subcarrier signature of through-seam leakage is a band-passed version of the open-air signature, distorted by the slot's frequency response. Detectable, but the saliency profile differs from R5's open-room measurement.
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- **R10** (foliage): the through-air maritime scenarios (man-overboard, pirate-skiff) reuse R10's free-space link budget directly. ~100 m at 2.4 GHz in clear-air conditions.
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- **R1** (CRLB): 4-anchor multistatic on a small ship's superstructure (4 corners of a 10 m wheelhouse) achieves ~30 cm ToA position precision; >10 m operational ranges put us in the room-pose-quality regime.
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- **R7** (mincut adversarial): essential for maritime. Single-link spoofing is easy (jammer on the dock). Multi-link consistency over 4 superstructure sensors is the only way to harden against this.
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## Honest scope
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- All numbers are **best-case** — ignore vessel vibration, electromagnetic noise from engine ignition systems, salt-spray on antennas, multipath from steel surfaces (which dominates real maritime CSI).
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- **Salt-spray** on PCB antennas degrades them by 3-10 dB after a few hours of operation. Marine-grade conformal coating extends this, but installation is harder than land deployments.
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- **Vibration** from engines / wave-slap modulates CSI at ~5-30 Hz. This is **in-band** with the gait frequencies used for R10's species classifier — making maritime gait-classification much harder than land.
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- **No GPS in steel compartments.** Multistatic positioning would need an alternative reference (inertial + RF anchors on the vessel itself). This is solvable but adds installation complexity.
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- The 200 m air-link range assumes a clear horizon. Real vessels have superstructure occluding many bearings; effective coverage is more like a 90° forward arc.
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## What this DOES enable
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- A **physically honest** maritime sensing roadmap that doesn't promise through-bulkhead capability that doesn't exist.
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- Clear product categories where ESP32 + RuView stack adds value: man-overboard surface detection, through-seam vitals, container tamper detection.
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- A predictive-maintenance angle (hatch-seal degradation) that has no current sensor alternative.
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## What this DOES NOT enable
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- Through-hull submarine sensing — physics says no at any practical bandwidth.
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- Underwater sensing at WiFi frequencies — physics says no.
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- Single-sensor multistatic localisation on a ship — vibration noise needs multi-sensor consensus.
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## Next ticks (R11 follow-ups)
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- Through-seam frequency response measurement. Place ESP32 + known signal source on opposite sides of a cabin door with a controlled gasket gap; characterise the slot transfer function vs. the slot-diffraction model.
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- Vibration-suppression filter: design a notch/comb filter that removes 5-30 Hz engine-modulation from CSI, validate on a real boat (no boat available in repo, but the filter design is reproducible).
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- ADR sketch for `cog-maritime-watch`: man-overboard + through-seam vitals as a maritime-specific cog package. Same ADR-103 pattern as `cog-person-count`, different model + different feature set.
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## Connection back
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- **R5** (saliency) — through-seam slot acts as a frequency-selective filter; the saliency profile through a seam differs from open-air saliency. New experiment opportunity.
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- **R6** (Fresnel) — Fresnel envelope still applies through seam, but the slot acts as an additional spatial filter, restricting the **effective transmit position**. The composite "Fresnel-zone-AND-slot-aligned" envelope is much narrower.
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- **R10** (foliage) — air-side maritime scenarios reuse R10's link-budget primitives unmodified.
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- **R12** (eigenshift) — the structure-detection problem is even harder on ships because the natural drift floor includes vessel motion and engine vibration. PABS over Fresnel+vibration basis is the maritime version.
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- **R14** (empathic appliances) — through-seam vitals + the V1 stress-responsive lighting framework could plausibly become "crew wellness monitoring in confined ship cabins". Privacy framework from R14 transfers directly.
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# Tick 10 — 2026-05-22 05:46 UTC
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**Thread:** R11 (maritime / through-bulkhead sensing)
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**Verdict:** Physics scrutiny re-frames "through-bulkhead" to "through-seam" — the romantic submarine-radar vision is impossible at WiFi bands; the actual product category is **gasket-leakage sensing**.
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## What shipped
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- `examples/research-sota/r11_maritime_propagation.py` — pure-numpy skin-depth + lossy-dielectric saltwater + slot-diffraction physics for 7 maritime scenarios.
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- `examples/research-sota/r11_maritime_results.json` — machine-readable predictions.
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- `docs/research/sota-2026-05-22/R11-maritime-sensing.md` — research note with the physics, verdicts table, feasible/infeasible verticals, honest scope, composition with prior threads.
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## Headline (verdict table)
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| Scenario | Verdict | Margin |
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|---|---:|---:|
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| Man-overboard surface @ 200 m | ✅ | +25 dB |
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| Through 10 mm closed steel door | ❌ | -938 dB |
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| Through cabin door **2 mm seam** | ✅ | **+31 dB** |
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| Through cabin door **5 mm seam** | ✅ | +39 dB |
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| Container w/ 30 mm vent slot | ✅ | +45 dB |
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| Submarine 30 mm pressure hull | ❌ | -929 dB |
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| Head 30 cm underwater | ❌ | -231 dB |
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Key physics: steel skin depth = **3.25 µm at 2.4 GHz** (impassable). Saltwater = **853 dB/m**. The loophole is **slot diffraction** through gasket seams.
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## Feasible verticals catalogued
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1. Man-overboard surface detection (200 m range)
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2. Through-seam crew vitals (lone-watch monitoring without compromise)
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3. Container tamper detection (cargo security)
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4. Hatch-seal integrity audit (predictive maintenance)
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5. Engine room thermal-anomaly detection (via condensation envelope)
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## What this matters for the loop
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R11 is the first thread that **explicitly debunks** a romantic 10-20y framing. The "through-bulkhead" terminology used in the original PROGRESS.md is physically wrong; the actual category is "through-seam". Replacing one vision with a more honest one is the kind of progress this loop is meant to surface.
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Composes cleanly:
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- R6 Fresnel envelope + slot diffraction = narrower composite envelope
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- R10 link-budget primitives reused unmodified for air-side maritime
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- R7 multi-link consistency essential for adversarial-resistant maritime
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- R14 privacy framework transfers directly to crew-cabin monitoring
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## Honest scope landed
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- Best-case ignores vessel vibration, engine ignition noise, salt-spray, multipath
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- Vibration (5-30 Hz) is **in-band** with R10's gait frequencies — maritime gait-classification harder than land
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- No GPS in steel compartments — alternative positioning needed
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## Coordination
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`ticks/tick-10.md`. No PROGRESS.md edit. Branch `research/sota-r11-maritime`.
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## Remaining threads
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R3 (cross-room re-ID), R4 (federated), R13 (contactless BP — likely negative-result candidate), R15 (RF biometric).
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~6.3h to cron stop. 10 threads landed.
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#!/usr/bin/env python3
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"""R11 — Maritime / through-bulkhead RF propagation.
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See docs/research/sota-2026-05-22/R11-maritime-sensing.md.
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Computes:
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- Steel bulkhead RF attenuation (skin depth) at WiFi bands
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- Seam-leakage diffraction loss
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- Saltwater attenuation (man-overboard surface sensing)
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- Composite link budget for three maritime scenarios
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Pure NumPy.
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"""
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from __future__ import annotations
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import argparse
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import json
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from pathlib import Path
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import numpy as np
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C = 2.998e8
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MU_0 = 4 * np.pi * 1e-7 # H/m
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EPS_0 = 8.854e-12 # F/m
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# Material properties (typical values)
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STEEL_SIGMA = 1.0e7 # S/m (mild steel conductivity)
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SALTWATER_SIGMA = 4.8 # S/m (35 ppt at 20 deg C)
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SALTWATER_EPSR = 81.0 # relative permittivity
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def skin_depth_m(freq_ghz: float, sigma: float, mu_r: float = 1.0) -> float:
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"""Classical skin depth: delta = 1 / sqrt(pi * f * mu * sigma)."""
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f = freq_ghz * 1e9
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return 1.0 / np.sqrt(np.pi * f * MU_0 * mu_r * sigma)
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def bulk_attenuation_db_per_mm(freq_ghz: float, sigma: float, mu_r: float = 1.0) -> float:
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"""Per-mm attenuation through bulk conductor."""
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delta = skin_depth_m(freq_ghz, sigma, mu_r)
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# Field decays as exp(-x/delta), power as exp(-2x/delta)
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# In dB per metre: 20/(delta*ln(10)) = 8.686/delta
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return 8.686 / delta / 1000 # divide by 1000 to get per-mm
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def saltwater_attenuation_db_per_m(freq_ghz: float) -> float:
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"""Saltwater attenuation per metre via lossy-dielectric model.
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alpha = (omega/c) * Im(sqrt(eps_r - j*sigma/(omega*eps_0)))
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Returns dB/m."""
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omega = 2 * np.pi * freq_ghz * 1e9
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eps_complex = SALTWATER_EPSR - 1j * SALTWATER_SIGMA / (omega * EPS_0)
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n_complex = np.sqrt(eps_complex)
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# Principal sqrt of (a - jb), b>0, has negative imag part. The wave
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# attenuation coefficient is alpha = omega/c * |Im(n)| -- take abs().
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alpha = omega * abs(n_complex.imag) / C # Np/m
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return float(8.686 * alpha) # dB/m
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def seam_diffraction_loss_db(seam_width_mm: float, freq_ghz: float) -> float:
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"""Approximate diffraction loss through a narrow slot in a conductor.
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For slot width w << lambda, the slot acts as a high-pass filter:
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L_slot = 20 * log10(lambda / (2 * w)) when w < lambda/2
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0 when w >= lambda/2
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Crude but captures the 1st-order physics. Real slot antennas are more
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complex; for forensic 'how much leaks through the door seal' work
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this is the right scale."""
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lam_mm = (C / (freq_ghz * 1e9)) * 1000
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if seam_width_mm >= lam_mm / 2:
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return 0.0
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return max(0.0, 20 * np.log10(lam_mm / (2 * seam_width_mm)))
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def maritime_scenario(name: str, freq_ghz: float, bulkhead_mm: float,
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seam_mm: float, free_air_m: float,
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saltwater_m: float = 0.0) -> dict:
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"""Composite path loss for a maritime sensing scenario."""
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# Free-space loss
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fspl = 32.45 + 20 * np.log10(freq_ghz) + 20 * np.log10(max(0.1, free_air_m + 0.1))
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# Bulkhead loss (if any propagation through metal)
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bulk_loss = bulkhead_mm * bulk_attenuation_db_per_mm(freq_ghz, STEEL_SIGMA)
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# Seam diffraction (alternative path)
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seam_loss = seam_diffraction_loss_db(seam_mm, freq_ghz) if seam_mm > 0 else 999.0
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# Saltwater loss
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water_loss = saltwater_m * saltwater_attenuation_db_per_m(freq_ghz)
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# The actual propagation path takes whichever is lower (bulk OR seam)
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best_metal_path = min(bulk_loss, seam_loss)
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total = fspl + best_metal_path + water_loss
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return {
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"scenario": name,
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"freq_ghz": freq_ghz,
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"fspl_db": fspl,
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"bulk_loss_db": bulk_loss,
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"seam_loss_db": seam_loss,
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"metal_path_used": "seam" if seam_loss < bulk_loss else "bulk",
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"metal_path_loss_db": best_metal_path,
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"saltwater_loss_db": water_loss,
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"total_loss_db": total,
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"esp32_link_budget_db": 121,
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"snr_margin_db": 121 - total - 10, # 10 dB SNR margin for DSP
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}
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def main():
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parser = argparse.ArgumentParser()
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parser.add_argument("--out", default="examples/research-sota/r11_maritime_results.json")
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args = parser.parse_args()
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# 1. Skin depth + per-mm attenuation
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materials_grid = {}
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for f in [2.4, 5.0]:
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delta_steel_um = skin_depth_m(f, STEEL_SIGMA) * 1e6 # micrometres
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att_steel = bulk_attenuation_db_per_mm(f, STEEL_SIGMA)
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att_water = saltwater_attenuation_db_per_m(f)
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materials_grid[f"{f}_GHz"] = {
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"steel_skin_depth_um": delta_steel_um,
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"steel_atten_dB_per_mm": att_steel,
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"saltwater_atten_dB_per_m": att_water,
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}
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# 2. Three maritime scenarios
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scenarios = [
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maritime_scenario("man-overboard, surface-floating", 2.4,
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bulkhead_mm=0, seam_mm=0, free_air_m=200, saltwater_m=0),
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maritime_scenario("man-overboard, head 30 cm underwater", 2.4,
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bulkhead_mm=0, seam_mm=0, free_air_m=200, saltwater_m=0.3),
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maritime_scenario("crew vitals through 10 mm steel cabin door (closed)", 2.4,
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bulkhead_mm=10, seam_mm=0, free_air_m=3),
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maritime_scenario("crew vitals through cabin door (2 mm seam gap)", 2.4,
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bulkhead_mm=10, seam_mm=2, free_air_m=3),
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maritime_scenario("crew vitals through cabin door (5 mm seam gap)", 2.4,
|
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bulkhead_mm=10, seam_mm=5, free_air_m=3),
|
||||
maritime_scenario("container intrusion (steel cargo container, 2 mm walls, 30 mm vent slot)", 2.4,
|
||||
bulkhead_mm=2, seam_mm=30, free_air_m=10),
|
||||
maritime_scenario("through hull (submarine, 30 mm pressure hull)", 2.4,
|
||||
bulkhead_mm=30, seam_mm=0, free_air_m=1),
|
||||
]
|
||||
|
||||
out = {
|
||||
"model": "skin-depth steel + lossy-dielectric saltwater + slot-diffraction seam",
|
||||
"materials": materials_grid,
|
||||
"scenarios": scenarios,
|
||||
}
|
||||
Path(args.out).parent.mkdir(parents=True, exist_ok=True)
|
||||
Path(args.out).write_text(json.dumps(out, indent=2))
|
||||
|
||||
# Print headlines
|
||||
print("=== Skin depth + bulk attenuation ===")
|
||||
for fkey, m in materials_grid.items():
|
||||
print(f" {fkey:>8} steel: skin={m['steel_skin_depth_um']:>6.2f} um, "
|
||||
f"attenuation={m['steel_atten_dB_per_mm']:>9.1f} dB/mm "
|
||||
f"saltwater={m['saltwater_atten_dB_per_m']:>6.1f} dB/m")
|
||||
print()
|
||||
print("=== Composite maritime scenarios @ 2.4 GHz ===")
|
||||
print(f"{'Scenario':<58} {'FSPL':>6} {'Metal':>6} {'Water':>6} {'Total':>6} {'Margin':>7}")
|
||||
for s in scenarios:
|
||||
print(f"{s['scenario']:<58} {s['fspl_db']:>6.1f} "
|
||||
f"{s['metal_path_loss_db']:>6.1f} {s['saltwater_loss_db']:>6.1f} "
|
||||
f"{s['total_loss_db']:>6.1f} {s['snr_margin_db']:>+7.1f}")
|
||||
print()
|
||||
print(f"Wrote {args.out}")
|
||||
|
||||
|
||||
if __name__ == "__main__":
|
||||
main()
|
||||
|
|
@ -0,0 +1,108 @@
|
|||
{
|
||||
"model": "skin-depth steel + lossy-dielectric saltwater + slot-diffraction seam",
|
||||
"materials": {
|
||||
"2.4_GHz": {
|
||||
"steel_skin_depth_um": 3.248736671806984,
|
||||
"steel_atten_dB_per_mm": 2673.654677948628,
|
||||
"saltwater_atten_dB_per_m": 852.7792439147287
|
||||
},
|
||||
"5.0_GHz": {
|
||||
"steel_skin_depth_um": 2.2507907903927653,
|
||||
"steel_atten_dB_per_mm": 3859.0881200843564,
|
||||
"saltwater_atten_dB_per_m": 867.7495416795573
|
||||
}
|
||||
},
|
||||
"scenarios": [
|
||||
{
|
||||
"scenario": "man-overboard, surface-floating",
|
||||
"freq_ghz": 2.4,
|
||||
"fspl_db": 86.07916660695635,
|
||||
"bulk_loss_db": 0.0,
|
||||
"seam_loss_db": 999.0,
|
||||
"metal_path_used": "bulk",
|
||||
"metal_path_loss_db": 0.0,
|
||||
"saltwater_loss_db": 0.0,
|
||||
"total_loss_db": 86.07916660695635,
|
||||
"esp32_link_budget_db": 121,
|
||||
"snr_margin_db": 24.92083339304365
|
||||
},
|
||||
{
|
||||
"scenario": "man-overboard, head 30 cm underwater",
|
||||
"freq_ghz": 2.4,
|
||||
"fspl_db": 86.07916660695635,
|
||||
"bulk_loss_db": 0.0,
|
||||
"seam_loss_db": 999.0,
|
||||
"metal_path_used": "bulk",
|
||||
"metal_path_loss_db": 0.0,
|
||||
"saltwater_loss_db": 255.83377317441858,
|
||||
"total_loss_db": 341.9129397813749,
|
||||
"esp32_link_budget_db": 121,
|
||||
"snr_margin_db": -230.91293978137492
|
||||
},
|
||||
{
|
||||
"scenario": "crew vitals through 10 mm steel cabin door (closed)",
|
||||
"freq_ghz": 2.4,
|
||||
"fspl_db": 49.88145871091758,
|
||||
"bulk_loss_db": 26736.546779486278,
|
||||
"seam_loss_db": 999.0,
|
||||
"metal_path_used": "seam",
|
||||
"metal_path_loss_db": 999.0,
|
||||
"saltwater_loss_db": 0.0,
|
||||
"total_loss_db": 1048.8814587109175,
|
||||
"esp32_link_budget_db": 121,
|
||||
"snr_margin_db": -937.8814587109175
|
||||
},
|
||||
{
|
||||
"scenario": "crew vitals through cabin door (2 mm seam gap)",
|
||||
"freq_ghz": 2.4,
|
||||
"fspl_db": 49.88145871091758,
|
||||
"bulk_loss_db": 26736.546779486278,
|
||||
"seam_loss_db": 29.891207909453847,
|
||||
"metal_path_used": "seam",
|
||||
"metal_path_loss_db": 29.891207909453847,
|
||||
"saltwater_loss_db": 0.0,
|
||||
"total_loss_db": 79.77266662037142,
|
||||
"esp32_link_budget_db": 121,
|
||||
"snr_margin_db": 31.227333379628575
|
||||
},
|
||||
{
|
||||
"scenario": "crew vitals through cabin door (5 mm seam gap)",
|
||||
"freq_ghz": 2.4,
|
||||
"fspl_db": 49.88145871091758,
|
||||
"bulk_loss_db": 26736.546779486278,
|
||||
"seam_loss_db": 21.93240773601309,
|
||||
"metal_path_used": "seam",
|
||||
"metal_path_loss_db": 21.93240773601309,
|
||||
"saltwater_loss_db": 0.0,
|
||||
"total_loss_db": 71.81386644693066,
|
||||
"esp32_link_budget_db": 121,
|
||||
"snr_margin_db": 39.18613355306934
|
||||
},
|
||||
{
|
||||
"scenario": "container intrusion (steel cargo container, 2 mm walls, 30 mm vent slot)",
|
||||
"freq_ghz": 2.4,
|
||||
"fspl_db": 60.14065230988498,
|
||||
"bulk_loss_db": 5347.309355897256,
|
||||
"seam_loss_db": 6.369382728340219,
|
||||
"metal_path_used": "seam",
|
||||
"metal_path_loss_db": 6.369382728340219,
|
||||
"saltwater_loss_db": 0.0,
|
||||
"total_loss_db": 66.5100350382252,
|
||||
"esp32_link_budget_db": 121,
|
||||
"snr_margin_db": 44.4899649617748
|
||||
},
|
||||
{
|
||||
"scenario": "through hull (submarine, 30 mm pressure hull)",
|
||||
"freq_ghz": 2.4,
|
||||
"fspl_db": 40.88207853739662,
|
||||
"bulk_loss_db": 80209.64033845883,
|
||||
"seam_loss_db": 999.0,
|
||||
"metal_path_used": "seam",
|
||||
"metal_path_loss_db": 999.0,
|
||||
"saltwater_loss_db": 0.0,
|
||||
"total_loss_db": 1039.8820785373966,
|
||||
"esp32_link_budget_db": 121,
|
||||
"snr_margin_db": -928.8820785373966
|
||||
}
|
||||
]
|
||||
}
|
||||
Loading…
Reference in New Issue