Precision positioning for deep‐water archaeology

Abstract

Underwater archaeology makes use a variety of tools for deep‐water exploration, but the defining characteristic of archaeology, what distinguishes the endeavor as scientific in purpose, is the quantifiable techniques employed for precision navigation. Precise positioning enables the collocation of archaeological results into a common reference frame, creating a persistent data products with the spatial context to enable interpretation. With this common context, data products such as site‐maps, micro‐bathymetric maps and photomosaics afford the capability to perform measurements with known accuracy and resolution, a key differentiator of the science of archaeology. Acoustic ranging is the meter stick of marine archeology. Archaeology has leveraged standard navigation techniques: long baseline (LBL) positioning, ultra‐short baseline (USBL) tracking, Doppler velocity log (DVL) dead‐reckoning, etc. However, the extreme precision required for archaeology has driven the development of new precise ranging instruments. This paper presents the capabilities and limitations of today's precision ranging instruments which use discrete sequence spread spectrum (DSSS) signal processing to provide the requisite performance. In addition to a technical discussion, the paper presents the results of recent field work in the Aegean, the Mediterranean and the East Coast of the Unites States.