SAR (synthetic aperture radar) tomography super-resolution imaging method

Abstract

The invention discloses an SAR (synthetic aperture radar) tomography super-resolution imaging method. The SAR tomography super-resolution imaging method includes registering obtained two-dimensional imaging results of various SAR tomography baselines, creating height-direction signals pixel by pixel according to the sequence of the baselines, realizing frequency modulation correction and constructing a redundancy matrix; and modeling a height-direction imaging problem into a sparse signal reconstruction problem according to the characteristic of sparsity of height-direction scattering coefficients, computing a sparse solution of the spares signal reconstruction problem by means of iteration by the aid of the constraint condition of the minimum weighted norm, and realizing height-dimensional imaging of an object. The method is applied to SAR tomography height-dimensional imaging, and problems that the quantity of two-dimensional SAR images in the same area and ( / or) trajectory distribution is uneven, and only a few parts of trajectory intervals (baselines) meet the Nyquist sampling theory are solved. In addition, by the aid of the method, energy of the object is more concentrated, namely, the resolution is improved, and the problem that the quantity of baselines is small is solved.

Description

technical field [0001] The invention belongs to the technical field of electronic signal processing, relates to the technical field of space remote sensing and air-ground observation information processing, and in particular to an airborne synthetic aperture radar (Synthetic Aperture Radar, SAR) tomographic three-dimensional imaging technology. Background technique [0002] Synthetic aperture radar is an important milestone in the development of radar technology in the 20th century. It uses the correlation of radar echo signals to accumulate the Doppler frequency shift of the echo signal during the radar movement process, thereby synthesizing the equivalent Radar aperture to achieve high-resolution imaging in azimuth. Because SAR adopts an active working mode, it performs imaging processing on the reflected echoes of electromagnetic waves emitted by itself, and is not limited by external environments such as light and temperature. It can realize all-day and all-weather regio...

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Problems solved by technology

Among them, the high-dimensional imaging mainly adopts methods based on spectral analysis (such as direct Fourier transform method, MUSIC, ESPRIT method, etc.). However, under actual conditions, SAR tomographic height-dimensional imaging will face two main problems: one is that the distribution of the baseline is not uniform, and sometimes the sampling interval is too large and the Nyquist theorem Contrary to the imaging results; the other is limited by the actual conditions, the number of baselines is very small, and the length of the synthetic aperture is too short, resulting in low resolution in the height dimension

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