where formula_46 is the typical SMI estimated matrix seen in the approximate direct method, formula_47 is the diagonal loading factor, and formula_48 is the identity matrix of the appropriate size. It should be seen that this is meant to improve the standard SMI method where SMI uses a smaller number of range bins in its average than the standard SMI technique. Since fewer samples are used in the training data, the matrix often requires stabilization in the form of diagonal loading.