Target velocity identification apparatus, target velocity identification program, and target velocity identification method

A target velocity identification apparatus which identifies a velocity of a target observed by a SAR (Synthetic Aperture Radar) comprising:

• a data input unit which inputs range-compressed data obtained by range compressing data on the target observed by the SAR based on a velocity vP of a SAR platform with the SAR mounted thereon, a distance R0 between the SAR and the target at a center of a synthetic aperture, and a synthetic aperture time τ;
• a predicted velocity input unit which inputs each of at least one velocity slower than a velocity vr of the target in a range direction and at least one velocity faster than the velocity vr of the target in the range direction, as a predicted velocity in the range direction;
• a reference function production unit which produces a reference function obtained from a relative distance between the SAR and the target expressed based on the velocity vP of the SAR platform and the velocity of the target, for each of a plurality of predicted velocities in the range direction input by the predicted velocity input unit, using a processing device, based on the plurality of predicted velocities in the range direction and a velocity of the target in an azimuth direction, thereby producing a plurality of reference functions;
• an azimuth compression process unit which azimuth compresses the range-compressed data input by the data input unit, based on each reference function of the plurality of reference functions produced by the reference function production unit, thereby generating a plurality of azimuth-compressed data, using the processing device;
• an amplitude value computation unit which computes an amplitude value of an image of the target in each azimuth-compressed data of the plurality of azimuth-compressed data generated by the azimuth compression process unit;
• and
• a velocity identification unit which identifies the velocity of the target in the range direction using a function of an amplitude value V0vrg expressed by the velocity vP of the SAR platform, the distance R0, the synthetic aperture time i, and a predicted velocity vr′ of the target in the range direction, based on the plurality of predicted velocities in the range direction input by the predicted velocity input unit and the amplitude value computed from each azimuth-compressed data by the amplitude value computation unit.

A target velocity identification apparatus which identifies a velocity of a target observed by a SAR (Synthetic Aperture Radar) comprising:

• a data input unit which inputs range-compressed data obtained by range compressing data on the target observed by the SAR;
• a predicted velocity input unit which inputs at least three predicted velocities including at least one velocity slower than a velocity vr of the target in a range direction and at least one velocity faster than the velocity vr of the target in the range direction, as predicted velocities in the range direction;
• a reference function production unit which produces a reference function obtained from a relative distance between the SAR and the target expressed based on a velocity vP of a platform with the SAR mounted thereon and the velocity of the target, for each of the predicted velocities in the range direction input by the predicted velocity input unit, based on the predicted velocities and a velocity of the target in an azimuth direction, using a processing device, thereby producing a plurality of reference functions;
• an azimuth compression process unit which azimuth compresses the range-compressed data input by the data input unit, based on each reference function of the plurality of reference functions produced by the reference function production unit, thereby generating a plurality of azimuth-compressed data, using the processing device;
• an amplitude value computation unit which computes an amplitude value of an image of the target in each azimuth-compressed data of the plurality of azimuth-compressed data generated by the azimuth compression process unit;
• and
• a velocity identification unit which computes a quadratic function of V0vrg=c1vr2c2vr+c3 (where c1, c2, and c3 are constants) from the at least three predicted velocities in the range direction input by the predicted velocity input unit and the amplitude value computed from each azimuth-compressed data by the amplitude value computation unit, by a predetermined method, and then identifies a velocity in the range direction at a base of the quadratic function as the velocity vr of the target in the range direction, using the processing device.

A target velocity identification program which identifies a velocity of a target observed by a SAR (Synthetic Aperture Radar), for causing a computer to execute:

• a data input process of inputting data on the target observed by the SAR under observation conditions of a velocity vP of a SAR platform with the SAR mounted thereon, a distance R0 between the SAR and the target at a center of a synthetic aperture, a wavelength λ of an electric wave emitted from the SAR, and a synthetic aperture time τ;
• a step size determination process of inputting the velocity vP of the SAR platform, the distance R0, the wavelength λ of the electric wave, and the synthetic aperture time τ being the observation conditions of the data input in the data input process to a function of an amplitude value V0vaz expressed by the velocity vP of the SAR platform, the distance R0, the wavelength λ of the electric wave, the synthetic aperture time τ, and a predicted velocity va′ of the target in an azimuth direction to compute the amplitude value V0vaz corresponding to the predicted velocity va′, identifying a range of the predicted velocity va′ in the azimuth direction where the amplitude value V0vaz becomes a predetermined value or larger, and then sets a velocity width equal to or smaller than a velocity width of the identified range to a step size Δva1;
• and
• an identification process execution process of identifying the velocity of the target in the azimuth direction using the step size Δva1 determined in the step size determination process.

A target velocity identification program which identifies a velocity of a target observed by a SAR (Synthetic Aperture Radar) for causing a computer to execute:

• a data input process of inputting range-compressed data obtained by range compressing data on the target observed by the SAR based on a velocity vP of a SAR platform with the SAR mounted thereon, a distance R0 between the SAR and the target at a center of a synthetic aperture, and a synthetic aperture time τ;
• a predicted velocity input process of inputting each of at least one velocity slower than a velocity vr of the target in a range direction and at least one velocity faster than the velocity vr of the target in the range direction, as a predicted velocity in the range direction;
• a reference function production process of producing a reference function obtained from a relative distance between the SAR and the target expressed based on the velocity vP of the SAR platform and the velocity of the target, for each of a plurality of predicted velocities in the range direction input in the predicted velocity input process, based on the plurality of predicted velocities in the range direction and a velocity of the target in an azimuth direction, thereby producing a plurality of reference functions;
• an azimuth compression process of azimuth compressing the range-compressed data input in the data input process, based on each reference function of the plurality of reference functions produced in the reference function production process, thereby generating a plurality of azimuth-compressed data;
• an amplitude value computation process of computing an amplitude value of an image of the target in each azimuth-compressed data of the plurality of azimuth-compressed data generated in the azimuth compression process;
• and
• a velocity identification process of identifying the velocity of the target in the range direction using a function of an amplitude value V0vrg expressed by the velocity Vp of the SAR platform, the distance R0, the synthetic aperture time τ, and a predicted velocity vr′ of the target in the range direction, based on the plurality of predicted velocities in the range direction input in the predicted velocity input process and the amplitude value computed from each azimuth-compressed data in the amplitude value computation process.

A target velocity identification program which identifies a velocity of a target observed by a SAR (Synthetic Aperture Radar) for causing a computer to execute:

• a data input process of inputting range-compressed data obtained by range compressing data on the target observed by the SAR;
• a predicted velocity input process of inputting at least three predicted velocities including at least one velocity slower than a velocity vr of the target in a range direction and at least one velocity faster than the velocity vr of the target in the range direction, as predicted velocities in the range direction;
• a reference function production process of producing a reference function obtained from a relative distance between the SAR and the target expressed based on a velocity vP of a platform with the SAR mounted thereon and the velocity of the target, for each of the predicted velocities in the range direction input in the predicted velocity input process, based on the predicted velocities and a velocity of the target in an azimuth direction, thereby producing a plurality of reference functions;
• an azimuth compression process of azimuth compressing the range-compressed data input in the data input process, based on each reference function of the plurality of reference functions produced in the reference function production process, thereby generating a plurality of azimuth-compressed data;
• an amplitude value computation process of computing an amplitude value of an image of the target in each azimuth-compressed data of the plurality of azimuth-compressed data generated in the azimuth compression process;
• and
• a velocity identification process of computing a quadratic function of V0vrg=c1vr2+c2vr+c3 (where c1, c2, and c3 are constants) from the at least three predicted velocities in the range direction input in the predicted velocity input process and the amplitude value computed from each azimuth-compressed data in the amplitude value computation process, by a predetermined method, and then identifying a velocity in the range direction at a base of the quadratic function as the velocity vr of the target in the range direction.

A target velocity identification method of identifying a velocity of a target observed by a SAR (Synthetic Aperture Radar) comprising:

• inputting data on the target observed by the SAR under observation conditions of a velocity vP of a SAR platform with the SAR mounted thereon, a distance R0 between the SAR and the target at a center of a synthetic aperture, a wavelength λ of an electric wave emitted from the SAR, and a synthetic aperture time τ;
• inputting the velocity vP of the SAR platform, the distance R0, the wavelength λ of the electric wave, and the synthetic aperture time τ being the observation conditions of the data to a function of an amplitude value V0vaz expressed by the velocity vP of the SAR platform, the distance R0, the wavelength λ of the electric wave, the synthetic aperture time τ, and a predicted velocity va′ of the target in an azimuth direction to compute the amplitude value V0vaz corresponding to the predicted velocity va′, identifying a range of the predicted velocity va′ in the azimuth direction where the amplitude value V0vaz becomes a predetermined value or larger, and then setting a velocity width equal to or smaller than a velocity width of the identified range to a step size Δva1;
• and
• identifying the velocity of the target in the azimuth direction using the step size Δva1.