4 Aug 2025

Acoustic and Seismic Wave Transmission Throughout the Multidomain Environment: Experimental Design, Methods, and Construction of a Prototypical Littoral Zone

Abstract: The future operational environment is projected to be a multidomain, transparent battlefield in which the Army must be able to act as both a supported and supporting force. An accurate detection and interpretation of acoustic and seismic signals propagating across land-air-water (LAW) interfaces are required to meet future requirements of a fully “transparent” domain. The LAW domains converge at the significant contested littoral zones. Historically, interpreting signals crossing media boundaries has been studied by stovepiping each distinct medium. These fragmented perspectives led to discrepancies in boundary and adjacent media descriptions and media-specific governing physics. No comprehensive physics framework exists to accurately predict how disorderly waveforms freely traverse LAW media boundaries. To understand these complex phenomena, a highly controlled physical experiment was designed and implemented. Repeatable controls were conducted. Epistemic uncertainty was decreased, and high waveform fidelity was maintained in the experimental setup by not interfering with wave transmission or sensor accuracy between controls. This report summarizes the experimental design, implementation, challenges, and repeatability.

6 Jan 2022

A Study on the Delta-Bullington Irregular Terrain Radiofrequency Propagation Model: Assessing Model Suitability for Use in Decision Support Tools

ABSTRACT: Modeling the propagation of radiofrequency signals over irregular terrain is both challenging and critically important in numerous Army applications. One application of particular importance is the performance and radio connectivity of sensors deployed in scenarios where the terrain and the environment significantly impact signal propagation. This report investigates both the performance of and the algorithms and assumptions underlying the Delta-Bullington irregular terrain radiofrequency propagation model discussed in International Telecommunications Union Recommendation P.526-15. The aim is to determine its suitability for use within sensor-planning decision support tools. After reviewing free-space, spherical earth diffraction, and terrain obstacle diffraction losses, the report discusses several important tests of the model, including reciprocity and geographic continuity of propagation loss over large areas of rugged terrain. Overall, the Delta-Bullington model performed well, providing reasonably rapid and geographically continuous propagation loss estimates with computational demands appropriate for operational use.

16 Nov 2020

Publication Notification: Distribution of the Two-Point Product of Complex Amplitudes in the Fully Saturated Scattering Regime

Abstract:  This Letter considers probability density functions (pdfs) involving products of the complex amplitudes observed at two points (which may, in general, involve separations in space, time, or frequency) in conditions of fully saturated scattering. First, the pdf is derived for the product of the complex amplitude at one point with the conjugate of the complex amplitude at another point. It is shown that the real and imaginary parts of this product each have a variance gamma pdf. Second, expressions are derived for several joint pdfs involving complex amplitude products and powers at two points.