Beam formation device, radar device, and beam formation method

1. A beam formation device comprising:

processing circuitry

to calculate a Doppler spectrum from a reception signal of each of a plurality of reception antennas, and to calculate a reception signal vector including the Doppler spectrum calculated from the reception signal of each of the reception antennas,

to calculate a correlation matrix regarding the reception signal vector,

to detect a target Doppler bin that is a Doppler bin in which a target signal is present from the correlation matrix and the reception signal vector,

to remove, from the correlation matrix, the target signal in the target Doppler bin so as to calculate a target-signal-removed correlation matrix from which the target signal has been removed,

to calculate an adaptive weighting of the reception signal vector from the target-signal-removed correlation matrix, and

to form an adaptive beam from the reception signal vector and the adaptive weighting.

2. The beam formation device according to claim 1 , wherein the processing circuitry generates, from among reception signals of the plurality of reception antennas, synthesis signals of one or more reception signals, and

the processing circuitry calculates a Doppler spectrum from each of the synthesis signals, and calculates a reception signal vector including the Doppler spectrum calculated from each of the synthesis signals.

3. The beam formation device according to claim 1 , wherein

the processing circuitry calculates Doppler spectrums of range bins from the reception signal of each of the reception antennas, and calculates, for each range bin, a reception signal vector including a Doppler spectrum of a corresponding range bin, calculated from the reception signal of each of the reception antennas,

calculates, for each range bin, a correlation matrix regarding the reception signal vector for each range bin,

detects, for each range bin, a target Doppler bin which is a Doppler bin in which the target signal is present from the correlation matrix for each range bin and the reception signal vector for each range bin,

removes the target signal in the target Doppler bin for each range bin from the correlation matrix for each range bin so as to calculate, for each range bin, a target-signal-removed correlation matrix from which the target signal has been removed,

calculates an adaptive weighting of the reception signal vector for each range bin from the target-signal-removed correlation matrix for each range bin, and

forms, for each range bin, an adaptive beam from the reception signal vector for each range bin and the adaptive weighting for each range bin.

4. The beam formation device according to claim 3 , wherein the processing circuitry generates, from among reception signals of the plurality of reception antennas, synthesis signals of one or more reception signals, and

calculates Doppler spectrums of range bins from each of the synthesis signals, and calculates, for each range bin, a reception signal vector including a Doppler spectrum of a corresponding range bin, calculated from each of the synthesis signals.

5. The beam formation device according to claim 1 , wherein

the processing circuitry calculates a plurality of eigenvectors in the correlation matrix,

forms a plurality of eigen beams from the plurality of eigenvectors and the reception signal vector, using the plurality of eigenvectors as a beam weighting for the reception signal vector, and

compares Doppler spectra of the plurality of eigen beams and a threshold, and detects the target Doppler bin on the basis of the comparison result between the Doppler spectra of the plurality of eigen beams and the threshold.

6. A radar device comprising:

processing circuitry

to calculate a Doppler spectrum from a reception signal of each of a plurality of reception antennas, and calculate a reception signal vector including the Doppler spectrum calculated from the reception signal of each of the reception antennas,

to calculate a correlation matrix regarding the reception signal vector,

to detect a target Doppler bin that is a Doppler bin in which a target signal is present from the correlation matrix and the reception signal vector,

to remove, from the correlation matrix, the target signal in the target Doppler bin so as to calculate a target-signal-removed correlation matrix from which the target signal has been removed,

to calculate an adaptive weighting of the reception signal vector from the target-signal-removed correlation matrix,

to form an adaptive beam from the reception signal vector and the adaptive weighting, and

to detect a target from the adaptive beam.

7. A beam formation method comprising:

calculating a Doppler spectrum from a reception signal of each of a plurality of reception antennas, and calculating a reception signal vector including the Doppler spectrum calculated from the reception signal of each of the reception antennas,

calculating a correlation matrix regarding the reception signal vector,

detecting a target Doppler bin that is a Doppler bin in which a target signal is present from the correlation matrix and the reception signal vector,

removing the target signal in the target Doppler bin from the correlation matrix, so as to calculate a target-signal-removed correlation matrix from which the target signal has been removed,

calculating an adaptive weighting of the reception signal vector from the target-signal-removed correlation matrix, and

forming an adaptive beam from the reception signal vector and the adaptive weighting.