Two-dimensional acquisition system using circular array

Claim 1

A method of finding the direction and frequency of a signal source whose signals are detected by a circular array of antenna elements, the method comprising the steps of: A. generating the two-dimensional Fourier transform in time and space of the signal ensemble consisting of the outputs of the circular array, thereby generating components each of which is associated with a spatial frequency and a temporal frequency; B. generating corrected components by applying to each component a correction function that differs only in the absence of the physical-angle-dependent phase factor from the inverse of the antenna pattern resulting when the antenna elements radiate signals whose temporal frequency is the temporal frequency associated with that component and whose phases advance with element position at the spatial frequency associated with that component; and C. performing a spatial Fourier transformation on the resulting ensemble of corrected components, the radial direction of the source of a given portion of the transform thereby being indicated by the spatial frequency of that portion.

Claim 2

A method of finding the direction and frequency of a signal source whose signals are detected by a circular array of antenna elements, the method comprising the steps of: A. generating the two-dimensional Fourier transform in time and space of the signal ensemble consisting of the outputs of the circular array, thereby generating components each of which is associated with a spatial frequency and a temporal frequency; B. generating corrected components by applying to each component a correction function that differs only in the absence of the physical-angle-dependent phase factor from the inverse of the antenna pattern resulting when the antenna elements radiate signals whose temporal frequency is the temporal frequency associated with that component and whose phases advance with element position at the spatial frequency associated with that component; and C. performing a spatial Fourier transformation on the resulting ensemble of corrected components, the radial direction of the source of a given portion of the transform thereby being indicated by the spatial frequency of that portion.

Claim 4

A device for finding the direction and frequency of a signal source whose signals are detected by a circular array of antenna elements, the device comprising: A. a two-dimensional Fourier-transform circuit for receiving as its inputs the signals from the antenna elements and for generating as its outputs a two-dimensional Fourier transform in space and time of its inputs and thereby generating components each of which is associated with a spatial frequency and a temporal frequency; B. correction circuits, connected to the two-dimensional Fourier-transform circuit, for generating corrected components by applying to each component a correction function that differs only in the absence of the physical-angle-dependent phase factor from the inverse of the antenna pattern resulting when the antenna elements radiate signals whose temporal frequency is the temporal frequency associated with that component and whose phases advance with element position at the spatial frequency associated with that component; and C. a spatial-Fourier-transform circuit, connected to receive the corrected components from the correction circuits, for performing a spatial Fourier transformation on the corrected components, the radial direction of the source of a given portion of the transform thereby being indicated by its spatial frequency.

Claim 5

A device for finding the direction and frequency of a signal source whose signals are detected by a circular array of antenna elements, the device comprising: A. a two-dimensional Fourier-transform circuit for receiving as its inputs the signals from the antenna elements and for generating as its outputs a two-dimensional Fourier transform in space and time of its inputs and thereby generating components each of which is associated with a spatial frequency and a temporal frequency; B. correction circuits, connected to the two-dimensional Fourier-transform circuit, for generating corrected components by applying to each component a correction function that differs only in the absence of the physical-angle-dependent phase factor from the inverse of the antenna pattern resulting when the antenna elements radiate signals whose temporal frequency is the temporal frequency associated with that component and whose phases advance with element position at the spatial frequency associated with that component; and C. a spatial-Fourier-transform circuit, connected to receive the corrected components from the correction circuits, for performing a spatial Fourier transformation on the corrected components, the radial direction of the source of a given portion of the transform thereby being indicated by its spatial frequency.