Forward-looking array SAR echo sparse acquisition and three-dimensional imaging method

Abstract

The invention discloses a forward-looking array SAR echo sparse acquisition and three-dimensional imaging method. The method comprises steps: 1, echo signal sparse features are used for optimizing a system transmission mode; 2, small-bandwidth signals are transmitted according to optimized parameters, and ground scattering echoes are received; 3, according to a course order, two-dimensional imaging treatment is carried out on a received scattering echo for each pulse; 4; range walk correction along the course is carried out; 5, echo data for each range gate along the course are arranged into echo vectors, and reconstruction of a scattering source scattering coefficient is realized through compressed sensing algorithm; and 6, the reconstructed scattering coefficient is positioned to the three-dimensional position, and reconstruction of a three-dimensional image is realized. the receiving sampling rate and the echo data amount of the forward-looking array SAR system are significantly reduced, the cost and the complexity of the system are thus reduced, and a new solution is provided for design and realization of the forward-looking array SAR system; and in addition, the method avoids the range migration correction problem when the compressed sensing technology is used for realizing ground scattering source sparse reconstruction.

Description

technical field [0001] The invention belongs to the field of radar data acquisition and signal processing, and particularly relates to signal acquisition and three-dimensional imaging of low sampling rate and small data volume of high-resolution forward-looking array SAR, and is generally applicable to three-dimensional observation of scenes directly ahead on low-altitude short-distance platforms. Background technique [0002] In the field of radar three-dimensional imaging, forward-looking array SAR has attracted the attention and research of many scientific research institutions and scholars in recent years. It is suitable for low-altitude and close-range earth observation of high-frequency band (such as millimeter wave) radar, and has the advantage of obtaining three-dimensional images of the observation scene in front of and below the platform in near real-time. A new way to work 24 / 7. Forward-looking array SAR adopts matched filtering of broadband transmission signals ...

AI Technical Summary

Problems solved by technology

At present, the high-resolution forward-looking array SAR 3D imaging system is facing the following problems: (1) The large signal bandwidth increases the complexity and cost of the system's transceiver components, and the current hardware level is also difficult to meet the requirements of the system's ultra-high range resolution. How to synthesize a high-resolution signal with a large bandwidth from an instantaneous small-bandwidth signal? (2) If the system meets the Nyquist sampling requirements, the three-dimensional high resolution will lead to a huge amount of data in the system, which will put a lot of pressure on storage, transmission and processing. How to use the sparseness of the observation scene to reduce the amount of echo data?

[0006] Since the sparse characteristics of the forward-looking array SAR in the cross-course and along-course directions are related to the scattering characteristics and terrain fluctuations of the actual ground scene, the above two methods cannot form a universally applicable sparse acquisition scheme.

Moreover, the optimal sparse characteristic of the forward-looking array SAR is not in the cross-course or along-course direction, and the sparse sampling effect of the above two methods is very limited

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