These modules extend the functionality of the radar altimeter model (RAM), and include:
1) Wrapper extension‘s goal is to automate terrain map (DEM) preparation for the measurement model while refreshing DEM only when needed (adaptive), accounting for attitude and radar angles (applicable to phase-array radars), providing control over computational efficiency (refresh frequency f and DEM data size A), and taking advantage of offline (non-real-time) data processing. First, coarse beam footprints (CFPs) are estimated. Then, orthogonal convex hulls (OCHs) around relevant DEM tiles are computed to iteratively update the region of interest.
2) Echo-Power extension uses radar range equation to provide a fast estimate of echo power, similar to frequency-based radar altimeter model. The approximations include fitting antenna gain and pre-averaging terrain exponents.
3) Post-Processing extension includes both histogram-based and runtime-based metrics, incl. estimates of autocorrelation times, and analysis of multimodality in measurement residual histograms due to radar clutter.
4) Elliptic-Cone extension allows to compute the elliptic-cone beam footprint and generate mesh for its oblique projection. It includes relevant local/global frame conversions, interpolations of terrain elevation function, containment checks for points in elliptic-cone quadric, and selection of points with minimum L2-norm.
