ABSTRACT Differential interferogram of space-borne SAR data may be affected by residual orbital fringes resulting from errors in the orbit (i.e. baseline) determination that hinder subsequent InSAR applications (deformation or elevation measurements). In this paper, an easy-to-use method was developed to remove the orbit errors in complex SAR interferogram in the radar coordinate system by accurately estimating the frequencies of the orbital ramp phase. The method first finds an approximate integer frequency by searching for the peak of the sum of the Fourier spectra of all the rows of the interferogram. It then uses the 100-order Burg spectral estimation algorithm to estimate the power spectrum for each row of the interferogram, and calculates the high-resolution power spectrum over the frequency range Hz. Finally, the method obtains the exact frequency of the orbital ramp phase in the row direction by searching for the peak of the sum of the high-resolution power spectra of all rows. By performing the same operations on all columns of the interferogram, the exact frequency in the column direction can be obtained. The orbital ramp phase can be calculated using these exact frequencies and be removed from the interferogram. Validation tests demonstrate that our method can accurately estimate the frequencies of the orbital ramp phase in the row and column directions, and eliminate the orbital ramp fringes from the simulated and actual interferograms. The proposed method only needs to calculate the high-resolution spectrum in a small frequency range, so the burden of calculation is light. The proposed method is easy to use since phase unwrapping or a priori satellite orbit information is not required.

中文翻译：

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用于去除 SAR 干涉图中轨道条纹的精确频率估计

摘要 星载SAR 数据的差分干涉图可能会受到轨道（即基线）确定误差所产生的残余轨道条纹的影响，从而阻碍后续的InSAR 应用（变形或高程测量）。本文开发了一种简单易用的方法，通过准确估计轨道斜坡相位的频率来消除雷达坐标系中复杂SAR干涉图中的轨道误差。该方法首先通过搜索干涉图所有行的傅立叶谱之和的峰值来找到近似整数频率。然后它使用 100 阶 Burg 谱估计算法来估计干涉图每一行的功率谱，并计算频率范围 Hz 上的高分辨率功率谱。最后，该方法通过搜索所有行的高分辨率功率谱之和的峰值，获得行方向轨道斜坡相位的准确频率。通过对干涉图的所有列执行相同的操作，可以获得列方向上的准确频率。可以使用这些精确频率计算轨道斜坡相位，并将其从干涉图中去除。验证测试表明，我们的方法可以准确估计行和列方向上轨道斜坡相位的频率，并从模拟和实际干涉图中消除轨道斜坡条纹。该方法只需要计算小频率范围内的高分辨率频谱，计算负担轻。