Polarimetric radar signal mapping process
First Claim
1. A process for obtaining information regarding a region of interest comprising the steps of:
- transmitting a first polarized polarimetric signal toward a first region using a first channel transmission means;
receiving a first scattering signal of the first polarized polarimetric signal scattered from within a plurality of subregions of the first region, for each subregion, the first scattering signal having a first polarimetric signal portion, B1, received by a first channel receiving means, and having a second polarimetric signal portion, B2, received by a second channel receiving means;
transmitting a second polarized polarimetric signal, distinct from said first polarized polarimetric signal, toward the first region using a second channel transmission means;
receiving a second scattering signal of the second polarized polarimetric signal scattered from each of the plurality of subregions, for each subregion, the second scattering signal having a third polarimetric signal portion, B3, received by a third channel receiving means, and having a fourth polarimetric signal portion, B4, received by a fourth channel receiving means;
generating a plurality of pixels, each said pixel including data corresponding to a subregion of said plurality of subregions, each said pixel generated using data corresponding with at least one collection of said signal portions B1, 1≦
i≦
4, where each Bi includes signals scattered from the subregion corresponding to the pixel;
selecting a sample collection of the plurality of pixels;
determining statistical expectation values representing entries of a predetermined expectation matrix using the data of at least one pixel from said sample collection;
obtaining values for one or more signal calibration variables by solving substantially simultaneously a first plurality of real valued equations for the values of a plurality of real unknowns corresponding to the real and imaginary portions of said plurality of signal calibration variables, said first plurality of real valued equations including a plurality of expectation equations, each expectation equation obtained by equating one of said expectation values, determined in said step of determining, to a theoretical expansion of the corresponding entry in the predetermined expectation matrix, said calibration variables relating to;
(1) corresponding zero or more channel imbalances between;
(a) said first channel transmission means and said second channel transmission means when transmitting said first polarized polarimetric signal and said second polarized polarimetric signal;
(b) said first channel receiving means and said second channel receiving means when receiving said first scattering signal;
(c) said third channel receiving means and said fourth channel receiving means when receiving said second scattering signal; and
(2) corresponding zero or more cross-talk polarimetric signal distortions between;
(d) said first channel receiving means and said second channel receiving means when receiving the first scattering signal;
(e) said third channel receiving means and said fourth channel receiving means when receiving the second scattering signal;
(f) said first channel transmission means and said second channel transmission means when transmitting the first polarized polarimetric signal;
(g) said first channel transmission means and said second channel transmission means when transmitting the second polarized polarimetric signal; and
(3) corresponding to a Faraday rotation angle;
calibrating one or more pixels using the values for said plurality of the signal calibration variables obtained in said step of obtaining;
using the calibrated pixels to obtain information regarding the region.
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Accused Products
Abstract
A process for mapping a region of interest using polarimetric radar signals is disclosed. The process provides for the polarimetric calibration of polarized signal data to account for distortions arising from cross-talk and channel imbalance during signal transmission and/or reception. Moreover, the process also can be used to correct for ionospheric signal distortions of polarized signals with low frequencies prone to Faraday rotations upon encountering the ionosphere. Such calibrations are accomplished with a reduced number of, typically ground-based, signal reflection devices used for calibrating the polarimetric signals to compensate for the above distortions.
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Citations
24 Claims
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1. A process for obtaining information regarding a region of interest comprising the steps of:
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transmitting a first polarized polarimetric signal toward a first region using a first channel transmission means; receiving a first scattering signal of the first polarized polarimetric signal scattered from within a plurality of subregions of the first region, for each subregion, the first scattering signal having a first polarimetric signal portion, B1, received by a first channel receiving means, and having a second polarimetric signal portion, B2, received by a second channel receiving means; transmitting a second polarized polarimetric signal, distinct from said first polarized polarimetric signal, toward the first region using a second channel transmission means; receiving a second scattering signal of the second polarized polarimetric signal scattered from each of the plurality of subregions, for each subregion, the second scattering signal having a third polarimetric signal portion, B3, received by a third channel receiving means, and having a fourth polarimetric signal portion, B4, received by a fourth channel receiving means; generating a plurality of pixels, each said pixel including data corresponding to a subregion of said plurality of subregions, each said pixel generated using data corresponding with at least one collection of said signal portions B1, 1≦
i≦
4, where each Bi includes signals scattered from the subregion corresponding to the pixel;selecting a sample collection of the plurality of pixels; determining statistical expectation values representing entries of a predetermined expectation matrix using the data of at least one pixel from said sample collection; obtaining values for one or more signal calibration variables by solving substantially simultaneously a first plurality of real valued equations for the values of a plurality of real unknowns corresponding to the real and imaginary portions of said plurality of signal calibration variables, said first plurality of real valued equations including a plurality of expectation equations, each expectation equation obtained by equating one of said expectation values, determined in said step of determining, to a theoretical expansion of the corresponding entry in the predetermined expectation matrix, said calibration variables relating to; (1) corresponding zero or more channel imbalances between; (a) said first channel transmission means and said second channel transmission means when transmitting said first polarized polarimetric signal and said second polarized polarimetric signal; (b) said first channel receiving means and said second channel receiving means when receiving said first scattering signal; (c) said third channel receiving means and said fourth channel receiving means when receiving said second scattering signal; and (2) corresponding zero or more cross-talk polarimetric signal distortions between; (d) said first channel receiving means and said second channel receiving means when receiving the first scattering signal; (e) said third channel receiving means and said fourth channel receiving means when receiving the second scattering signal; (f) said first channel transmission means and said second channel transmission means when transmitting the first polarized polarimetric signal; (g) said first channel transmission means and said second channel transmission means when transmitting the second polarized polarimetric signal; and (3) corresponding to a Faraday rotation angle; calibrating one or more pixels using the values for said plurality of the signal calibration variables obtained in said step of obtaining; using the calibrated pixels to obtain information regarding the region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A process for obtaining information regarding an ionosphere comprising the steps of:
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transmitting a first polarized polarimetric signal toward a region using a first channel transmission means; receiving a first scattering signal of the first polarized polarimetric signal scattered from within a plurality of subregions of the region, for each subregion, the first scattering signal having a first polarimetric signal portion, b1, received by a first channel receiving means, and having a second polarimetric signal portion, b2, received by a second channel receiving means; transmitting a second polarized polarimetric signal, distinct from said first polarized polarimetric signal, toward the region using a second channel transmission means; receiving a second scattering signal of the second polarized polarimetric signal scattered from each of the plurality of subregions, for each subregion, the second scattering signal having a third polarimetric signal portion, B3, received by a third channel receiving means, and having a fourth polarimetric signal portion, B4, received by a fourth channel receiving means; generating a plurality of pixels, each said pixel including data corresponding to a subregion of said plurality of subregions, each said pixel generated using data corresponding with at least one collection of said signal portions B1, 1≦
i≦
4, where each Bi includes signals scattered from the subregion corresponding to the pixel;selecting a sample collection of the plurality of pixels; determining statistical expectation values representing entries of a predetermined expectation matrix using the data of at least one pixel from said sample collection; obtaining values for one or more signal calibration variables by solving substantially simultaneously a first plurality of real valued equations for the values of a plurality of real unknowns corresponding to the real and imaginary portions of said plurality of signal calibration variables, said first plurality of real valued equations including a plurality of expectation equations, each expectation equation obtained by equating one of said expectation values, determined in said step of determining, to a theoretical expansion of the corresponding entry in the predetermined expectation matrix, at least one of said signal calibration variables being a Faraday rotation angle, one or more additional said signal calibration variables relating to; (1) corresponding zero or more channel imbalances between; (a) said first channel transmission means and said second channel transmission means when transmitting said first polarized polarimetric signal and said second polarized polarimetric signal; (b) said first channel receiving means and said second channel receiving means when receiving said first scattering signal; (c) said third channel receiving means and said fourth channel receiving means when receiving said second scattering signal; and (2) corresponding zero or more cross-talk polarimetric signal distortions between; (d) said first channel receiving means and said second channel receiving means when receiving the first scattering signal; (e) said third channel receiving means and said fourth channel receiving means when receiving the second scattering signal; (f) said first channel transmission means and said second channel transmission means when transmitting the first polarized polarimetric signal; (g) said first channel transmission means and said second channel transmission means when transmitting the second polarized polarimetric signal; identifying the Faraday rotation angle value obtained with said region; using the identification of the Faraday rotation angle value and said region to obtain information regarding the ionosphere.
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Specification