Calculating a virtual boresight vector of an antenna array
AssigneeL3 Technologies, Inc.
InventorsRadivoje Zarubica, Samuel C. Kingston, Merle L. Keller
Life of this patent
Estimating the term…
Abstract
A virtual boresight vector for an antenna array can be calculated. The virtual boresight vector defines the direction an antenna array is pointing and can be used to ensure that angle of arrival measurements are performed with high accuracy. The virtual boresighting process can include positioning a calibration node at two different locations in order to obtain different covariance matrices. With the covariance matrices and based on knowing the angle between the two locations, an angle of arrival node can perform a process to calculate a precise angle between the antenna array and the second location.
Claims20
A method, performed by an angle of arrival node in an angle of arrival system, for determining a virtual boresight vector of an antenna array, the method comprising:
- generating a first measured covariance matrix for a signal emitted by a calibration node that is positioned at an arbitrary location;
- generating a second measured covariance matrix for a signal emitted by the calibration node that is positioned at a permanent location different from the arbitrary location;
- generating a measured difference covariance matrix from the first and second measured covariance matrices;
- determining an angle difference between an angle of the arbitrary location relative to an antenna array of the angle of arrival node and an angle of the permanent location relative to the antenna array;
- for each of a number of assumed angles of the permanent location relative to the antenna array:
- calculating a first estimated covariance matrix for the assumed angle;
- calculating a second estimated covariance matrix for a corresponding angle that is offset from the assumed angle;
- and
- generating an estimated difference covariance matrix from the first and second estimated covariance matrices;
- comparing the measured difference covariance matrix to each estimated difference covariance matrix to identify one of the estimated difference covariance matrices that most closely matches the measured difference covariance matrix;
- and
- calculating, from the assumed angle that corresponds with the identified estimated difference covariance matrix, an angle between the antenna array and the calibration node.
A method for determining a virtual boresight vector of an antenna array, the method comprising:
- positioning a calibration node at an arbitrary location;
- while the calibration node is positioned at the arbitrary location, causing an angle of arrival node to generate a first measured covariance matrix for a signal emitted by the calibration node;
- positioning the calibration node at a permanent location different from the arbitrary location;
- while the calibration node is positioned at the permanent location, causing the angle of arrival node to generate a second measured covariance matrix for a signal emitted by the calibration node;
- providing input to the angle of arrival node that identifies an angle difference between an angle of the arbitrary location relative to an antenna array of the angle of arrival node and an angle of the permanent location relative to the antenna array;
- and
- calculate, from the first and second measured covariance matrixes and the input, an angle between the antenna array and the calibration node at the permanent location.
An angle of arrival system comprising:
- an angle of arrival node having an antenna array and a modem coupled to the antenna array;
- and
- a calibration node that is configured to emit a signal;
- wherein the modem is configured to perform the following:
- generate a first measured covariance matrix for the signal when the calibration node is positioned at an arbitrary location;
- generate a second measured covariance matrix for the signal when the calibration node is positioned at a permanent location different from the arbitrary location;
- generate a measured difference covariance matrix from the first and second measured covariance matrices;
- determine an angle difference between an angle of the arbitrary location relative to the antenna array and an angle of the permanent location relative to the antenna array;
- for each of a number of assumed angles of the permanent location relative to the antenna array:
- calculate a first estimated covariance matrix for the assumed angle;
- calculate a second estimated covariance matrix for a corresponding angle that is offset from the assumed angle;
- and
- generate an estimated difference covariance matrix from the first and second estimated covariance matrices;
- compare the measured difference covariance matrix to each estimated difference covariance matrix to identify one of the estimated difference covariance matrices that most closely matches the measured difference covariance matrix;
- and
- calculate, from the assumed angle that corresponds with the identified estimated difference covariance matrix, an angle between the antenna array and the calibration node.
Dependencies are inferred from the claim text.