Passive array tracking of a continuous wave transmitting projectile

Differential Doppler measurements by a passive array are used to track an unstable CW source moving in a ballistic trajectory - e.g., a projectile carrying a proximity fuse. The ballistic equations of motion couple frequency measurements at various sections along the track with the track parameters at any arbitrary time - e.g., at impact. A nonlinear weighted least-square method is used to estimate the track parameters, and the resulting error covariance matrix is derived. A numerical example demonstrates the relative contributions of various frequency measurements to the estimation accuracy.