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## A Precise Baseline Estimation Method Based on Non-stationary Signal Analysis

Yanjie Zhang(1) and Prinet Veronique(2)

(1) National Laboratory of Pattern Recognition(NLPR), Institute of Automation (IOA) P.O. Box 2728, Beijing (100080), China
(2) National Laboratory of Pattern Recognition, the Institute of Automation, 100080, France

Abstract

The precision of baseline plays a great role in InSAR processing. In the two main applications of InSAR processing: DEM generation and DInSAR processing. An accurate estimation of the baseline length is very important. There have been many baseline estimation methods. Now the Delft University provides the free download of precise orbit data, and these satellite track state vectors can be used to do baseline estimation well. To use those data, the unified tool is also needed. In this paper, a new and precise baseline estimation method is proposed. No tie points or ground control points are needed. Only the primary orbit track parameters are used. And it can be considered as a “blind” baseline estimation method. For some baseline estimation method, the coordinate conversion from Cartesian coordinate to image coordinate must be done. And the conversion is based on the following pixel positioning method by solving the nonlinear function set first proposed by Curlander[6] .The Cartesian coordinate of each pixel in the SAR image can be determined. From the above three equations, the uncertainty of the satellite state vectors and the Doppler Centroid will have a great effect on the positioning result. In this paper, a new baseline estimation is proposed based on Non- stationary Signal Analysis. In paper [7], the author has proposed an interferogram flattening method using the instantaneous frequency (IF). From his method, the IF can be modeled as a polynomial. In our method, the baseline estimation is based on the extraction of the phase due to the flat earth from the raw interferogram using the knowledge of the Time Frequency Distribution (TFD). The interferometric phase is corresponding to the real geometry when the SAR was acquiring the image. And the precise flat earth phase is also decided by that geometry. The calculated baseline length B will be the right result.

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Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry

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