Stratified Waveguide Acoustic Probing (SWAP): Autonomous Sub-Thermocline Waveguide Penetration and Closed-Loop Dual-Mode Acoustic Inversion

Stratified Waveguide Acoustic Probing (SWAP): Autonomous Sub-Thermocline Waveguide Penetration and Closed-Loop Dual-Mode Acoustic Inversion [Abstract]This white paper introduces Stratified Waveguide Acoustic Probing (SWAP), a novel physical computing paradigm designed to overcome the fundamental limitations of oceanic acoustic shadow zones. Conventional linear sonar architectures fail in stratified maritime environments where steep thermal gradients (thermoclines) refract acoustic energy, blinding sensors to sub-surface anomalies at extreme signal-to-noise ratios (SNR ≤ -18.0 dB). SWAP leverages the 100,000-node physical continuum of the Resonance Processing Unit (RPU) to execute a closed-loop dual-mode sensing and transmission cycle: Passive Discovery: Utilizing Spatial Stochastic Resonance (SSR) to harvest ambient environmental entropy as thermodynamic fuel, autonomously isolating undisclosed sub-threshold tonals without prior frequency knowledge. In-Situ Forging: Real-time crystallization of bespoke Acoustic Resonant Sequences (ARS)—ground-state waveforms physically matched to the local refractive impedance of the water column. Active Illumination: Conducting coherent acoustic energy through the thermocline into deep shadow zones (z = 400m) via bidirectional Laplacian waveguide conduction. Empirical Hardware-in-the-Loop (HIL) validation using Software-Defined Radio (SDR) confirms deterministic discovery with single-bin accuracy (Δf = 0.01 Hz) and coherent shadow-zone energy delivery (10.01% conservation). This work establishes a verifiable physical-layer baseline for covert oceanographic telemetry, AUV exploration, and autonomous sub-surface wave governance.