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Measurement of topography using polarimetric synthetic aperture radar (SAR)

  • US 5,552,787 A
  • Filed: 10/10/1995
  • Issued: 09/03/1996
  • Est. Priority Date: 10/10/1995
  • Status: Expired due to Fees
First Claim
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1. A polarimetric processor for measuring azimuth direction terrain slopes comprised of:

  • a radar for transmitting and receiving analog electromagnetic signals of alternately horizontally and vertically polarization;

    an analog-to-digital converter where the analog electromagnetic signals are converted into a digital data bit stream;

    a formatter for formatting the digital bit stream;

    means for recording and storing the digital data bit stream;

    a playback unit for removing the digital data from the storage means;

    a digital correlator for correlating the digital data bit stream;

    a computer for receiving the correlated digital data bit stream and computing(a) a Stokes-Mueller matrix, M, utilizing the digitized analog electromagnetic signals of alternately horizontally and vertically polarization extracted from the playback unit and correlated;

    (b) a polarimetric signature, σ



    χ

    ), utilizing the Stokes-Mueller matrix, M;

    (b) a first, a=a'"'"'=[-1,0,0], and second initial value, a'"'"'=[1,0,0], for a pixel or pixels;

    (c) a first gradient utilizing the method of steepest descent for the first and second initial values;

    (d) updating the first and second initial values utilizing the gradient;

    (e) normalizing the first and second initial values;

    (f) repeat steps (c)-(e) utilizing the normalized first and second values until the maximum has been found;

    (g) σ

    1 and σ

    2 utilizing a new first and second values;

    (h) a comparison of σ

    1 and σ

    2,(i) a value for Ellipticity, χ

    =sin-1 (a3)/2, and Orientation, Ψ

    =tan-1 (a2 /a1)/2;

    (j) a combination of individual pixel maximum locations;

    (k) a initialization of elevations for each row of azimuthal pixels by a known elevation point;

    (l) an integration of slope values in an azimuthal direction; and

    means for plotting the ellipticity and orientation to produce a presentation that is a direct measure of terrain azimuthal slopes and a derived estimate of terrain elevation.

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