Space/time/frequency methods in adaptive radar - New Jersey ...

100Figure 5.12 Post-Doppler range plots using 60 training points with training outsidethe target region. SMI, EIG, and non-adaptive techniquesSMI weight vector will remain unchanged (up to a gain factor). Hence, inclusion ofthe target in this case has no impact on the array performance. Conversely, whenthe steering and the target vectors differ, presence of the target will cause a shiftin the weight vector. In this case, the target is interpreted as an interference andthe array acts to reject it. Since in practice it is difficult to ensure that the targetand steering vector are equal (no pointing error and perfect calibration), to precludetarget cancellation, covariance matrix estimation is done without the range cells inthe vicinity of the one tested. Reduced rank methods constrain the weight vectorto the noise subspace. These methods tend to be less susceptible to the presenceof the target in the training data, since a few target cells may cause no change inthe interference/noise subspace partition [59]. Indeed, the covariance matrix may beexpressed