Discrete source location by adaptive antenna techniques
First Claim
1. A radar receiving system suitable for determining the approximate direction to a source of signal energy, said system comprising:
- a phased array antenna having a plurality of separate antenna elements;
means for sampling the signal at the separate elements to provide values corresponding to the sampled signals;
means for forming at least one polynomial expression, with the coefficients of said expression being derived from said values;
means for finding the roots of said polynomial expression;
means for determining the closeness of said roots to the unit circle in at least one complex plane;
means for selecting the roots Which satisfy a predetermined closeness criterion; and
means for providing the angular direction in the complex plane to said selected roots, said angular direction of the selected roots corresponding to the angular direction to the source of signal energy.
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Accused Products
Abstract
A signal processor for radar systems having phased array antenna structures. The processor determines the angle of arrival of the signal from a discrete energy source. The separate elements or output ports of the antenna structure are sampled to form a matrix of signal values. These values are converted into polynomial expressions consistent with one of the spectral estimating methods of maximum entropy, maximum likelihood, and thermal noise. The roots of the polynomial expressions are found and compared to the distance of the unit circle in a pole-zero diagram. Roots sufficiently close to the unit circle are selected as representative of the source signal peaks and the angular directions to such sources are determined by the corresponding angular location of the selected roots in the pole-zero diagram.
32 Citations
15 Claims
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1. A radar receiving system suitable for determining the approximate direction to a source of signal energy, said system comprising:
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a phased array antenna having a plurality of separate antenna elements; means for sampling the signal at the separate elements to provide values corresponding to the sampled signals; means for forming at least one polynomial expression, with the coefficients of said expression being derived from said values; means for finding the roots of said polynomial expression; means for determining the closeness of said roots to the unit circle in at least one complex plane; means for selecting the roots Which satisfy a predetermined closeness criterion; and means for providing the angular direction in the complex plane to said selected roots, said angular direction of the selected roots corresponding to the angular direction to the source of signal energy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of determining the approximate direction to a source of signal energy in a radar system having an antenna with a plurality of separate antenna elements, said method including the steps of:
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sampling the signal at the separate radar antenna elements to obtain sample values; forming a covariance matrix from said sample values; deriving at least one polynomial expression from the values in said covariance matrix; finding the roots of said polynomial expressions; determining the closeness of the roots to the unit circle in a complex plane; and correlating the location of any roots determined to be within a predetermined value of closeness to the unit circle with the actual direction to the signal source. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification