Algorithms for analysis of ballistic radar data

This report describes the algorithms used for processing ballistic radar data at the Norwegian Defence Research Establishment (FFI). A ballistic radar measures the velocity history of projectiles. This is used to determine the drag coefficient (CD) of the projectile, which in turn is used in ballistic trajectory simulations. The given radar data is primarily radial velocity data. These data are first smoothed and parallax corrected. A tangential velocity history is then calculated by assuming a ballistic trajectory, given an elevation, wind and possibly secondary aerodynamic forces. Given the tangential velocity history, together with meteorological information, a drag coefficient (CD) is determined. After smoothing, this results in a CD versus Mach number curve. The obtained CD function is checked by comparing a simulated radial velocity history with the corresponding measured one. The report also describes a method used at FFI to determine the ballistics of ricochets from radar measurements and a method for processing spin measurements. The algorithms are implemented in an in-house code called Weibelwin (programmed in C#).