PURPOSE: To correctly identify even input information which is partially wrong at high speed by providing input layers, intermediate layers, and output layers and performing the nonlinear transformation of a signal from an input until with the intermediate layers and output layers.

CONSTITUTION: Units 4r1, 4r2... of the input layer 1 correspond to radars r1, r2... and output units 5p1, 5p2... correspond to platform names p1, p2.... The units 4r1, 4r2... are coupled with intermediate layers 2a and 2b corresponding to output layers 3a, 3b... classified by plural platform classification types. The intermediate layers 2a, 2b... are coupled with output nits of output layers of the same types. The weight Wij of the coupling between units 2 and (j) and the threshold value θj of the unit (j) are given in advance. The units (j) of the intermediate layers 2a, 2b... receive input signals i1 and i2 from coupled input units and output them according to a specific expression. Output layer units output output signals from intermediate units of coupled intermediate layers according to a specific expression instead of the input signals. As the arithmetic result, the output unit which outputs the maximum value is regarded as a platform.