NEXA is a research and advanced development project aiming at the development of a generic software platform for real-time and post-process trajectory determination. The platform, also named NEXA, will be GeoNumerics' future navigation software platform.
The NEXA architecture concept is similar to that of GENA (separation between a generic platform and model components). GENA is GeoNumerics' generic and extensible network adjustment system.
NEXA will be a tool to compute static and kinematic solutions from observations made by GNSS receivers, inertial measurement units and other navigation instruments.
The NEXA research deals with advanced prediction, filtering and smoothing techniques based on but different from those of the classical Kalman Filter (KF) and Iterated Extended Kalman Filter (IEKF) and of its many different varieties and flavors.
The main goal of the GAL project was to revisit the method of strapdown airborne gravimetry (SAG) in light of the Galileo(a) system. In traditional SAG, strapdown inertial measurements and GPS ranging signals (code and phase measurements) are used, where strapdown inertial measurements are obtained from inertial measurement units (IMUs).
Gravimetry is the measurement of the strength of the gravity field of a celestial body. In modern geodesy, many times, gravimetry is synonymous to the measurement of the differences between an actual gravity field and a [global] model of that gravity field. The Earth gravity field is approximated by global and local models that are computed by geodesists from gravity measurements and some other types of geodetic observations like level differences or deflections of the vertical. While global gravity models might be highly accurate they are of limited spatial resolution –i.e., of 100 km wavelengths and lower– and local gravimetric densifications are required.