Deutsches Zentrum Fur Luft-und Raumfahrt E.v.

Deutsches Zentrum Fuer Luft-und Raumfahrt E.v

Rolf Scheiber

Alberto Moreira

Josef Mittermayer

Pau Prats

Marc RODRÍGUEZ-CassolÀ

To suppress cross-ambiguities in the examination of an ice region or dry region by means of aircraft- or aerospace-supported radar echo sounding, the region to be examined is overflown by a radar sensor () by multiple compatible radar sensors of the same operating wavelength on multiple spatially separated, substantially parallel paths, wherein the radar signal data received on each path are recorded. The radar signal data recorded for each of the different paths are summed coherently and using a weighting to form a radargram, wherein an adaptive complex-valued weighting for each of the individual paths is performed using a geometrical model which takes into account the topography of the environment of the region to be examined. The weighting for every depth of the examined region is determined by solving a system of linear equations from which is calculated a synthetic antenna pattern which has zeros in the direction of the ambiguities. Implementation in radar systems for echo sounding in ice and in dry regions on earth or other planets and extraterrestrial objects.

Method for examining an ice region or dry region using radar echo sounding

Sub-aperture processing is carried out. Within each sub-aperture, range compression and a correction for the target range variation are carried out. Baseband azimuth scaling is used for processing the azimuth signal, wherein a long azimuth reference function and thus a wide azimuth dimension are prevented. The scaling range is not constant and depends on the range, which is not equal to the original range vector. It is calculated such that, in combination with a subsequent derotation step, constant azimuth scanning is achieved for all ranges. The selected derotation function, which is applied in the azimuth time domain, makes it possible for all the targets to be in base band, in this way varying the effective chirp rate. Since the phase is purely quadratic because of the azimuth scaling step, it is thus possible to use an optimal filter which takes account of the effective chirp rate. IFFT results in a focused image, and a final phase function in the time domain allows phase maintenance. Application for SAR, SONAR and seismic raw data processing in the TOPS mode, as well as other modes which make use of the antenna polar diagram being scanned in the azimuth and/or elevation direction.

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Puchhelm, Germany

Rolf Scheiber