Fast interpolation for Global Positioning System (GPS) Satellite Orbits

In this report, we discuss and compare several methods for polynomial interpolation of Global Positioning Systems ephemeris data. We show that the use of difference tables is more efficient than the method currently in use to construct and evaluate the Lagrange polynomials

Evaluation of an integrated GPS/INS system for shallow-water AUV navigation (SANS)

Many possible Autonomous Underwater Vehicle (AUV) missions require a high degree of navigutional accuracy. The Global Positioning System (GPS) is capable of providing this accuracy. However, intermittent reception caused by either wave action or deliberate submergence will cause the loss of GPS position fix information for periods extending from several seconds to minutes. The SANS system is designed to demonstrate the feasibility of using a low-cost strapped-clown Inertial Measurement Unit (IMU) to navigate between GPS fixes. It is anticipated that navigational accuracy comparable to GPS is possible between fixes.This research was supported in part by the National Science Foundation under Grant BCS- 9306252 to the Naval Postgraduate School

An Experimental Study of an Integrated GPS/INS System for Shallow-Water AUV Navigation (SANS)

The Naval Postgraduate School's "Phoenix" AUV has thus far been operated only in a test pool environment. In preparation for open water testing, currently planned for mid-1996, a series of towfish experiments are being conducted in Monterey Bay to investigate the feasibility of integrated GPS/INS transit mode navigation, in significant sea states, using a GPS antenna mounted only a few inches above the AUV body. In this configuration, either wave action or deliberate submergence will cause loss of GPS position fix information for periods extending from several seconds to a few minutes. The main research question being investigated is, therefore, to determine whether or not a low cost strapped down IMU can be used to navigate accurately between GPS fixes. Our goal is to achieve inertial navigation accuracy comparable to GPS accuracy during periods between successive GPS fixes. Experimental results reported in this paper indicate that this is feasible