Range/azimuth/elevation angle ship imaging for ordnance control

Claim 2

In conjunction with an airborne synthetic aperture radar system having an interferometer antenna and a display, a method for forming high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising the steps of: a) processing the received signals from the scatterers comprising the ship target to obtain estimates of the net doppler producing velocities resulting from the respective motions of the radar bearing aircraft and the ship; and b) determining from the estimated doppler producing velocities the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target.

Claim 3

In conjunction with an airborne synthetic aperture radar system having an inteferometer antenna and a display, a method for forming high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising the steps of: a) processing the received signals from the scatterers comprising the ship target to obtain estimates of (1) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (2) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; and b) determining from the estimated doppler producing velocities the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target.

Claim 4

In conjunction with an airborne synthetic aperture radar system having an inteferometer antenna and a display, a method for forming high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising the steps of: a) processing the received signals from the scatterers comprising the ship target to obtain estimates of (1) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (2) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; and b) determining from the estimated doppler producing velocities the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target.

Claim 5

A method as recited in Claim 1 or 2 including the further step of displaying the formed imagery of the ship target.

Claim 6

A method as recited in Claim 3 wherein the displayed imagery of the ship target includes a range/azimuth angle projection, an azimuth angle/elevation profile projection, and a range/elevation profile projection.

Claim 7

In conjunction with an airborne synthetic aperture radar system having an interferometer antenna and a display, a method for forming and displaying high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising the steps of: a) compensating using an estimate of the net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship for phase variations in the received signals from the scatterers comprising the ship target resulting from the respective motions of the radar bearing aircraft and the ship; b) processing in conjunction with azimuth angle and elevation interferometric techniques the compensated received signals to obtain estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; c) determining from the estimated cross line-of-sight relative velocity and the estimated orthogonal velocity the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target; d) displaying the formed imagery of the ship target; and e) centering using the estimated error in the estimated line-of-sight relative velocity the displayed imagery of the ship target.

Claim 8

In conjunction with an airborne synthetic aperture radar system having an interferometer antenna and a display, a method for forming and displaying high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising the steps of: a) compensating using an estimate of the net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship for phase variations in the received signals from the scatterers comprising the ship target resulting from the respective motions of the radar bearing aircraft and the ship; b) processing in conjunction with azimuth angle and elevation interferometric techniques the compensated received signals to obtain estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; c) determining from the estimated cross line-of-sight relative velocity and the estimated orthogonal velocity the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target; d) displaying the formed imagery of the ship target; and e) centering using the estimated error in the estimated line-of-sight relative velocity the displayed imagery of the ship target.

Claim 9

A method as recited in Claim 5 wherein the step of processing the compensated received signals includes; a) measuring interferometrically the azimuth and elevation angles of the received signal in each doppler filter in each range bin; and b) obtaining from predefined characteristics derived from a weighted multivariate regression fit to the doppler processed azimuth and elevation angle measurement data the estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship.

Claim 10

A method as recited in Claim 5 or 6 wherein the centered displayed imagery of the ship target includes a range/azimuth angle projection, an azimuth angle/ elevation profile projection, and a range/elevation profile projection.

Claim 11

In conjunction with an airborne synthetic aperture radar system having an interferometer antenna and a display, a method for forming and displaying high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising the steps of: a) steering the pointing of the interferometer antenna boresight to provide radar illumination of the ship target; b) controlling the range sampling timing so that corresponding samples from pulse-to-pulse over the integration interval correspond to the same range increment of the ship target; c) compensating using an estimate of the net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship for phase variations in the received signals from the scatterers comprising the ship target resulting from the respective motions of the radar bearing aircraft and the ship; d) measuring interferometrically the azimuth and elevation angles of the compensated recieved signal in each doppler filter in each range bin; e) obtaining from selected regression constants derived from a weighted least squares multivariate regression fit to the doppler processed azimuth and elevation angle measurement data estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross-line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; f) determining from the estimated cross line-of-sight relative velocity and the estimated orthogonal velocity the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target; g) displaying the formed imagery including a range/ azimuth angle projection, an azimuth angle/elevation profile projection, and a range/elevation profile projection of the ship target; and h) centering using the estimated error in the estimated line-of-sight relative velocity the displayed imagery of the ship target.

Claim 12

In conjunction with an airborne synthetic aperture radar system having an interferometer antenna and a display, a method for forming and displaying high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising the steps of: a) steering the pointing of the interferometer antenna boresight to provide radar illumination of the ship target; b) controlling the range sampling timing so that corresponding samples from pulse-to-pulse over the integration interval correspond to the same range increment of the ship target; c) compensating using an estimate of the net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship for phase variations in the received signals from the scatterers comprising the ship target resulting from the respective motions of the radar bearing aircraft and the ship; d) measuring interferometrically the azimuth and elevation angles of the compensated recieved signal in each doppler filter in each range bin; e) obtaining from selected regression constants derived from a weighted least squares multivariate regression fit to the doppler processed azimuth and elevation angle measurement data estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross-line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; f) determining from the estimated cross line-of-sight relative velocity and the estimated orthogonal velocity the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target; g) displaying the formed imagery including a range/ azimuth angle projection, an azimuth angle/elevation profile projection, and a range/elevation profile projection of the ship target; and h) centering using the estimated error in the estimated line-of-sight relative velocity the displayed imagery of the ship target.

Claim 13

A method as recited in Claim 8 including the further steps of cursoring a designated resolution cell of the displayed imagery of the ship target; and tracking from aperture to aperture the range and interferometric azimuth angle of the designated resolution target cell.

Claim 14

A method as recited in Claim 9 including the further step of applying to the cursor location on an aperture to aperture basis a tracking correction to compensate for the rotation of the ship about the axis orthogonal to both the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship.

Claim 15

ll. A method as recited in any of Claims 8 to 10 including the further steps of obtaining and utilising smoothed elevation locational values in forming the displayed azimuth angle/elevation profile and range/ elevation profile image projections of the ship target.

Claim 18

A method as recited in Claim 13 including the further step of scaling the cross-range dimension of the displayed inverse synthetic aperture radar profile image projection of the ship target.

Claim 19

A method as recited in Claim 14 including the further step of converting the displayed scaled inverse synthetic aperture radar profile image projection of the ship target to a stretched inverse synthetic aperture radar profile image projection.

Claim 20

In combination with an airborne synthetic aperture radar system having an interferometer antenna and a display, image signal processing means for forming high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising; a) means for processing the received signals from the scatterers comprising the ship target to obtain estimates of the net doppler producing velocities resulting from the respective motions of the radar bearing aircraft and the ship; and b) means for determining from the estimated doppler producing velocities the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target.

Claim 21

In combination with an airborne synthetic aperture radar system having an interferometer antenna and a display, image signal processing means for forming high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising; a) means for processing the received signals from the scatterers comprising the ship target to obtain estimates of the net doppler producing velocities resulting from the respective motions of the radar bearing aircraft and the ship; and b) means for determining from the estimated doppler producing velocities the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target.

Claim 22

In combination with an airborne synthetic aperture radar system having an interferometer antenna and a display image signal processing means for forming high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising: a) means for processing the received signals from the scatterers comprising the='ship target to obtain estimates of (1) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (2) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; and b) means for determining from the estimated doppler producing velocities the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target.

Claim 23

In combination with an airborne synthetic aperture radar system having an interferometer antenna and a display image signal processing means for forming high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising: a) means for processing the received signals from the scatterers comprising the='ship target to obtain estimates of (1) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (2) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; and b) means for determining from the estimated doppler producing velocities the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target.

Claim 24

A combination as recited in Claim 16 or 17 wherein the image signal processing means further include means for displaying the formed imagery of the ship target.

Claim 25

A combination as recited in Claim 25 wherein the displayed imagery of the ship target includes a range/ azimuth angle projection, an azimuth angle elevation profile projection, and a range/elevation profile projection.

Claim 26

In combination with an airborne synthetic aperture radar system having an interferometer antenna and a display, image signal processing means for forming an displaying high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising: a) means for compensating using an estimate of the net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship for phase variations in the received signals from the scatterers comprising the ship target resulting from the respective motions of the radar bearing aircraft and the ship; b) means for processing in conjunction with azimuth angle and elevation interferometric techniques the compensated received signals to obtain estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; c) means for determining from the estimated cross line-of-sight relative velocity and the estimated orthogonal velocity the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target; d) means for displaying the formed imagery of the ship target; and e) means for centering using the estimated error in the estimated line-of-sight relative velocity the displayed imagery of the ship target.

Claim 27

In combination with an airborne synthetic aperture radar system having an interferometer antenna and a display, image signal processing means for forming an displaying high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising: a) means for compensating using an estimate of the net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship for phase variations in the received signals from the scatterers comprising the ship target resulting from the respective motions of the radar bearing aircraft and the ship; b) means for processing in conjunction with azimuth angle and elevation interferometric techniques the compensated received signals to obtain estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; c) means for determining from the estimated cross line-of-sight relative velocity and the estimated orthogonal velocity the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target; d) means for displaying the formed imagery of the ship target; and e) means for centering using the estimated error in the estimated line-of-sight relative velocity the displayed imagery of the ship target.

Claim 28

A combination as recited in Claim 20 wherein the processing means include: a) means for measuring interferometrically the azimuth and elevation angles of the received signal in each doppler filter in each range bin; and b) means for obtaining from predefined characteristics derived from a weighted multivariate regression fit to the doppler processed azimuth and elevation angle measurement data the estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship.

Claim 29

A combination as recited in Claim 20 or 21 wherein the centered displayed imagery of the ship target includes a range/azimuth angle projection, an azimuth angle/elevation profile projection and a range/elevation profile projection.

Claim 30

In combination with an airborne synthetic aperture radar system including a multiple section interferometer antenna operatively connected to the input to a two channel receiver and doppler processing system, and a display operatively connected to the output of said two channel receiver and doppler processing system, image signal processing means for forming and displaying high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising: a) means for steering the pointing of the interferometer antenna boresight to provide radar illumination Of the ship target; b) means for controlling the range sampling timing so that corresponding samples from pulse-to-pulse over the integration interval correspond to the same range increment of the ship target; c) means for compensating using an estimate of the net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship for phase variations in the received signals from the scatterers comprising the ship target resulting from the respective motions of the radar bearing aircraft and the ship; d) means for measuring interferometrically the azimuth and elevation angles of the compensated received signal in each doppler filter in each range bin; e) means for obtaining from selected regression constants derived from a weighted least squares multivariate regression fit to the doppler processed azimuth elevation angle measurement data estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and in the radar line-of-sight to the center of rotation tracking point of the ship; f) means for determining from the estimated cross line-of-sight relative velocity and the estimated orthogonal velocity the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target; g) means for displaying the formed imagery including a range/azimuth angle projection, an azimuth angle/ elevation profile projection, and a range/elevation profile projection of the ship target; and h) means for centering using the estimated error in the estimated line-of-sight relative velocity the displayed imagery of the ship target.

Claim 31

In combination with an airborne synthetic aperture radar system including a multiple section interferometer antenna operatively connected to the input to a two channel receiver and doppler processing system, and a display operatively connected to the output of said two channel receiver and doppler processing system, image signal processing means for forming and displaying high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions comprising: a) means for steering the pointing of the interferometer antenna boresight to provide radar illumination Of the ship target; b) means for controlling the range sampling timing so that corresponding samples from pulse-to-pulse over the integration interval correspond to the same range increment of the ship target; c) means for compensating using an estimate of the net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship for phase variations in the received signals from the scatterers comprising the ship target resulting from the respective motions of the radar bearing aircraft and the ship; d) means for measuring interferometrically the azimuth and elevation angles of the compensated received signal in each doppler filter in each range bin; e) means for obtaining from selected regression constants derived from a weighted least squares multivariate regression fit to the doppler processed azimuth elevation angle measurement data estimates of (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and in the radar line-of-sight to the center of rotation tracking point of the ship; f) means for determining from the estimated cross line-of-sight relative velocity and the estimated orthogonal velocity the values of predetermined system parameters to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target; g) means for displaying the formed imagery including a range/azimuth angle projection, an azimuth angle/ elevation profile projection, and a range/elevation profile projection of the ship target; and h) means for centering using the estimated error in the estimated line-of-sight relative velocity the displayed imagery of the ship target.

Claim 32

A combination as recited in Claim 23 wherein the image signal processing means further include means for cursoring a designated resolution cell of the displayed imagery of the ship target; and means for tracking from aperture to aperture the range and interferometric azimuth angle of the designatede resolution target cell.

Claim 33

A combination as recited in Claim 24 wherein the image signal processing means further include means for applying to the cursor location on an aperture to aperture basis a tracking correction to compensate for the rotation of the ship about the axis orthogonal to both the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship.

Claim 34

A combination as recited in any of Claims 23 to 25 wherein the image signal processing means further include means for obtaining and utilizing smoothed elevation locational values in forming the displayed azimuth angle/ elevation profile and range/elevation profile image projections of the ship target.

Claim 35

A combination as recited in any of Claims 23 to 26 wherein the image signal processing means further include: a) means for smoothing using the doppler processed azimuth and elevation angle measurement data obtained over multiple apertures the estimates obtained for (1) the error in the estimated net doppler producing line-of-sight velocity of the radar bearing aircraft relative to the ship, (2) the net doppler producing cross line-of-sight velocity of the radar bearing aircraft relative to the ship, and (3) the net doppler producing velocity in the direction orthogonal to the cross line-of-sight relative velocity and the radar line-of-sight to the center of rotation tracking point of the ship; . b) means for determining from the smoothed estimated cross line-of-sight relative velocity and the smoothed estimated orthogonal velocity the values of the predetermined system parameters including synthetic aperture radar integration time and pulse repetition frequency and doppler. filter bandwidths and spacings to be used predictively in the succeeding integration interval in forming the high resolution imagery of the ship target; c) means for displaying the formed imagery of the ship target; and d) means for centering using the smoothed estimated error in the estimated line-of-sight relative velocity the displayed imagery of the ship target.

Claim 36

A combination as recited in any of Claims 16 to 27 wherein the image signal processing means further include means for forming and displaying an inverse synthetic aperture radar profile image projection of the ship target.

Claim 37

A combination as recited in Claim 28 wherein the image signal processing means further include means for scaling the cross-range dimension of the displayed inverse synthetic aperture radar profile image projection of the ship target.

Claim 38

A combination as recited in Claim 29 wherein the image signal processing means further include means for converting the displayed scaled inverse synthetic aperture radar profile image projection of the ship target to a stretched inverse synthetic aperture radar profile image projection.