According to one embodiment, a calculating of a weight includes which is calculating a covariance matrix by applying a process (Post-Doppler process) of selecting a plurality of banks after execution of a Doppler filter process to a specified number of pulses of the received signal, and extracting a plurality of arbitrary bank parts from among the plurality of selected banks which are used for the calculation of the covariance matrix, and calculating a plurality of weights on a phase and an amplitude, from a matrix of the plurality of extracted bank parts.