Communications: directive radio wave systems and devices (e.g. – Determining direction – Interferometer
Reexamination Certificate
2008-04-15
2008-04-15
Alsomiri, Isam (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Determining direction
Interferometer
C342S148000, C342S188000, C342S195000
Reexamination Certificate
active
07358891
ABSTRACT:
Apparatus and a method utilizing correlation interferometer direction finding for determining the azimuth and elevation to an aircraft at long range and flying at low altitudes above water with a transmitting radar while resolving multipath signals. The signals from the radar are received both directly and reflected from the surface of the water using horizontally polarized and vertically polarized antenna arrays, are digitized and are stored in separate covariant matrices. Eigenvalues for the eigenvectors of the matrices processed on signal samples recorded on horizontally polarized X arrays are compared to the eigenvalues for the eigenvectors of the covariance matrices processed on signal samples recorded on vertically polarized X arrays. Incident field polarization is associated with the antenna array measurements that yield the strongest eigenvalue. The eigenvector and eigenvalues for the strongest signal are selected and used for subsequent signal processing. An initial global search assuming mirror sea-state reflection conditions using the signal eigenvector having the strongest eigenvalue is performed to yield an approximate elevation α and azimuth β to the aircraft. The approximate values are then used as the starting point for a subsequent conjugate gradient search to determine accurate elevation α and azimuth β to the aircraft.
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Martel Robert T.
Struckman Keith A.
Alsomiri Isam
BAE Systems Information and Electronic Systems Integration Inc.
Funk Joseph E.
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