arXiv subjects

John L. Spiesberger

Publications and source records attributed to John L. Spiesberger.

7 recordsLinked to original sources

arXiv2026

Blinded Evaluation of Oceanic Sound Source Locations via Sequential Bound Estimation

A non-linear, non-Bayesian method called sequential bound estimation (SBE) derived 100% confidence intervals of location (CIL) for 219 explosions in the ocean from measurements of their time differences of arrivals among five widely-spaced time-unsynchronized receivers on the ocean bottom. The explosion's locations were measured with the global positioning system. A blind evaluation revealed all 219 explosions were within their CIL. The probability this could happen by chance is $4 \times 10^{-116}$. The explosions were detonated in shallow water on the eastern continental shelf of the U.S. over the so-called New England Mud Patch.

physics.ao-ph↗

arXiv2026

Unreported large errors from two PAMGuard three-dimensional localizers of whale calls

Confidence intervals of location (CIL) of calling marine mammals, derived from time-differences-of-arrival (TDOA) between receivers, depend on errors of TDOAs, receiver location, clocks, sound speeds, and location method. When these errors are minuscule, simulations yield small errors of PAMGuard's 3D simplex localizer when click sounds of beaked and sperm whales originate in a 1000 x 1000 x 1000 $\mbox{m}^3$ region using five receivers having horizontal and vertical separations of 1000 m and 150 m respectively. Realistic uncertainties of sound speed up to $\pm 10$ m/s lead to errors up to $10^{14}$ m. With clocks maintained by atomic standards and common practice of correcting TDOA from synchronization measurements at the start and end of an experiment, errors of location are up to $10^{4}$ m. Errors up to $10^2$ and $10^3$ m are found when the receiver's locations are uncertain within 10 and 40 m respectively. Errors of PAMGuard's 3D hyperbolic localizer are almost independent of the above uncertainties, yielding errors of location up to about $10^4$ m even when simulated errors are minuscule. Causes of PAMGuard's 3D location errors are unknown. These algorithms are briefly compared to another method designed to yield a reliable CIL.

physics.ao-ph↗

arXiv2025

Supersonic and Superluminal Energy and Speed of Information via Temporal Interference in a Dispersionless Environment

Numerical implementation of a theory yields acoustic wave packets whose peak-to-peak speeds, $c_{3d}$, are supersonic in a dispersionless medium due to temporal interference between direct and boundary-reflected paths. The effect occurs when the source and receiver are near each other and at least one is within $c\tilde{δt}/2$ of the boundary, where $c$ is the phase speed of propagation in the medium, and $\tilde{δt}$ is the smallest temporal separation between the paths at which interference first occurs. This direct+reflected path effect is distinct from previously-observed superluminal phenomena and theories including quantum tunneling, cavity vacuum fluctuations, and group speeds due to anomalous dispersion. For temporally interfering direct+reflected paths, simulations yield a speed of information less than $c$. The speed of information from the interfering paths can exceed the speed derived from propagation only along the direct path. We conjecture these results will also hold for electromagnetic (EM) wave propagation. If so, we prove the speed of information is less than or equal to the speed of light in a vacuum, so the effect does not violate special relativity. These theoretical and simulation results, as well as their conjectured EM extension, should be readily accessible to experimental verification.

physics.gen-ph↗

arXiv2024

Slowing and stopping the speed of sound

Temporal interference between direct and surface-reflected paths induces large variation in the group speed of an acoustic signal between a source and receiver. This speed goes to zero when the source and receiver approach one another and are within $c \tilde{δt}/2$ of the surface, where $c$ is the in-situ speed of sound and $\tilde{δt}$ is the smallest temporal separation between the paths at which interference initiates. At greater depths, the group speed can drop by many orders of magnitude. The effect diminishes far from a receiver as the size of the delay shrinks relative the overall time of propagation. The phenomenon is of great importance for methods designed to locate sounds via time differences of arrival (TDOA) as the group speed between a sound and each receiver may differ by orders of magnitude, a phenomenon that invalidates the geometrical interpretation of location by hyperboloids. Isodiachronic geometries are required to derive valid locations. Analogous to gravitational black holes, where the speed of light is zero at the event horizon, ``three-dimensional acoustical black holes'' an be present at acoustical receivers.

physics.class-ph↗

arXiv2019

Locating Objects with Signal Times Amongst Shadows and Black Holes in Two-Dimensional Models

Calling mammals, ships, and many other objects have been commonly located during the last century with two-dimensional (2D) models from measurements of signal time even when the objects are not on the 2D surface. The overwhelmingly common method for locating signals with 2D models takes signal speed as constant. Distance is computed by multiplying this speed by signal time. For monostatic, bistatic, and Time Differences of Arrival (TDOA) measurements, the distances constrain locations to circles, ellipses, and hyperbolas respectively, whose intersections yield location. However, the speed needed to obtain correct locations depends on the horizontal separation between object and instrument. In fact, if their horizontal separation is zero the speed needed for correct location must also be zero. In light of this singularity, methods are derived for generating extremely reliable confidence intervals for location and identifying regions of the 2D model where a 3D model is needed. Because speeds needed for correct location are spatially in-homogeneous in the extreme, isosigmachrons and isodiachrons emerge as natural geometries for interpreting location instead of ellipses and hyperbolas. These issues are caused by choice of coordinates, and the same phenomena occur in general relativity regarding the speed of light and black holes.

physics.class-ph↗

arXiv2012

Computation of Horizontal Correlation of Sound in Presence of Internal Waves in Deep Water and Long Distances

Numerical solutions are given for a parabolic approximation of the acoustic wave equation at 200 and 250 Hz in two and three spatial dimensions to determine if azimuthal coupling in the cross-range coordinate significantly affects horizontal correlation in the presence of internal gravity waves in the sea. No evidence for coupling is found for distances of 4000 km and less. This implies that accurate solutions are possible using computations from uncoupled vertical slices. Shapes of horizontal correlation are closer to shapes given by two theories than at lower frequencies.

physics.ao-ph↗

arXiv2005

Locating where Transient Signals Travel in Inhomogeneous Media

Locating where transient signals travel between a source and receiver requires a final step that is needed after using a theory of diffraction such as the integral theorem of Helmholtz and Kirchhoff. Introduced here, the final step accounts for interference between adjacent apertures on a phase screen by adaptively adjusting their phase and amplitude, yielding a hierarchy of energy contributions to any desired window of signal travel time at the receiver. The method allows one to check errors in ray theory at finite wavelengths. Acoustic propagation at long distance in the oceanic waveguide (50-100 Hz, 0.05 s resolution) has significant deviations from ray theory. The boundary condition of zero pressure at the surface of the ocean appears to cause sound to travel in a nearly horizontal trajectory for a much greater distance near the surface than predicted by rays. The first Fresnel zone is an inappropriate scale to characterize where transient sounds travel near a ray path as assumed by a standard scattering theory. Instead, the Fresnel zone is too large by an order of magnitude for cases investigated here. Regions where sounds travel can have complicated structures defying a simple length scale. These results are applicable to the physics of underwater sound, optics, radio communication, radar, geophysics, and theories of wave-scattering.

physics.class-ph↗