Abstract: Vehicle tracking and position predicting apparatus includes an improved Kalman velocity filter feedback loop having a forward gain matrix for loop coordinate error factors and those of their derivatives; and position predicting computing apparatus in the loop feedback path between the system output and an input error node. Sensor reference target signals (e.g., range, bearing and elevation) are connected as inputs to the filter error node.In accordance with one aspect of the present invention, sensor coordinate reference errors from the input error node are converted to target reference coordinates. Pursuant to a further aspect of the present invention, the gain matrix is varied dependent upon sensor coordinate variables. Gain matrix variations are thus independent of geometry and sensor reference coordinates.