A pure-Cartesian formulation for tracking filters
Roger L. Gray · IEEE Transactions on Aerospace and Electronic Systems · 1993
A pure-Cartesian formulation is presented for angle-only and angle-plus-range tracking filters. Unlike conventional angle-only filters, which use target elevation and bearing as measurements, the filter expresses the sensor measurements in Cartesian coordinates. Consequently, the filter performs equally well for any line-of-sight (LOS) geometry, even when target elevation approaches or is equal to +or-90 degrees .>