Transient response and design methodology of an Applebaum adaptive filter

In the spread-spectrum/antijam scenario, significant processing gains can be achieved by the insertion of an antijam (AIS) filter in the receiver in front of the detector. In the present work the transient response of an FIR (finite impulse response) AIS filter, whose tap weights are updated by the Applebaum algorithm, is derived. An expression is then derived for the transient response of the correlator. Given an expression for the transient response of the correlator, the correlation may be maximized as a function of the loop gain and steering vector gain contained in the Applebaum algorithm. Moreover, this may be done at any time in the transient correlation response as opposed to the typical steady-state case. To motivate the use of the Applebaum algorithm, it is contrasted to the LMS (least mean square) algorithm and shown to have a significantly larger correlation. A filter design example is provided