Spiess, Fred N. | Engineering Papers

NASA NTRS1997

Program for Continued Development and Use of Ocean Acoustic/GPS Geodetic Techniques

Under prior NASA grants our group, with collaboration from scientists at the CalTech Jet Propulsion Lab (JPL), visualized and carried out the initial development of a combined GPS and underwater acoustic (GPS/A) method for determining the location of points on the deep sea floor with accuracy relevant to studies of crustal deformation. Under an immediately preceding grant we built, installed and surveyed a set of the necessary seafloor marker precision transponders just seaward of the Cascadia Subduction Zone off British Columbia. The JPL group carried out processing of the GPS data.

Spiess, Fred N.↗

NASA NTRS1990

Method and system for measuring sound velocity

A method and system for determining the speed of sound in a fluidic medium by determining the travel time of an acoustical signal a predetermined distance in a fluidic medium by generating a cyclical reference signal of a predetermined frequency and transmitting a portion of the reference signal through the medium. The transmitted portion of the reference signal is received after travelling a predetermined distance in the fluidic medium. The cycles of the cyclical reference signal are counted during the period of time between the transmitting and receiving of the portion of the reference signal wherein the travel time of the portion of the reference signal, is the number of cycle counts divided by the frequency. The speed of the acoustical signal through the fluidic medium is a function of the path length divided by the travel time.

Boegeman, Dwight E.↗