Qiu Xiaolan

Non-linear chirp scaling algorithm for one-stationary bistatic SAR

This paper points out the non-linear property of the differential RCM along range direction in one-stationary bistatic SAR, and compares it with the monostotic case. Then it deduces out a non-linear chirp scaling factor to identify the RCM of all targets in the swath. The implementary processes of a non-linear chirp scaling algorithm for one-stationary bistatic SAR are then described detailedly. Finally, the simulating results present here validate the correctness of the algorithm.

An advanced 2-D spectrum for high-resolution and MEO spaceborne SAR

In this paper, an advanced range equation is presented for high-resolution and medium-earth-orbit (MEO) synthetic aperture radar (SAR). Besides an additional linear component, this new equation has a similar formalism to conventional hyperbolic range equation (CHRE), so is called the advanced hyperbolic range equation (AHRE). Incorporating with this additional linear coefficient and the other two parameters, the cubic Taylor series expansion of AHRE has exactly the same value as which of the actual range history. Furthermore, a two-dimensional (2-D) spectrum based on AHRE is derived, which is useful for developing efficient SAR algorithms. Simulations validate AHRE and show its advantages in highresolution and MEO spaceborne SAR cases.

A novel single-channel SAR-GMTI method based on defocusing shifted difference

A novel single channel SAR-GMTI method is proposed in this paper. When the azimuth mismatch filter performs compression, it induces shifted difference between the stationary and moving targets because of having different Doppler center. The proposed method employs this character to separate moving targets from stationary targets. It can produce two images by pulse compression which make use of two symmetrical mismatch filters in azimuth direction, and then cancel stationary and retain moving targets by subtracting one image from another. Compared with traditional methods, it is applicable to both low and high squint case and the detection capability is significantly improved. The simulation results validate the effectiveness of the proposed method.

Ionosphere estimation and correction for geosynchronous SAR based on point target deviation between range sub-images

Ionosphere is an important factor in high-resolution spaceborne synthetic aperture radar (SAR) and geosynchronous (GEO) SAR. An approach based on point target deviation between range sub-images is proposed in this paper to estimate and correct the ionosphere. Due to the dispersion effect, the ionosphere causes propagation delay deviation in range subimages with different carrier frequency. This deviation can be used to estimate the total electron content (TEC) along the propagation path, and then the ionospheric effects can be corrected according to the signal model deduced out in this paper. The simulation results show that our approach is valid and robust.

The effects of multi-path scattering on the SAR image of cylinder cavity

In this paper, the effects of multi-path scattering mechanisms on SAR image is deduced through range Doppler algorithms (RDA). The conclusion that the cloud phenomenon appeared due to the multi-path scattering mechanisms is detained. Through the analysis, the cloud caused by the multi-path in the down range is corresponding to focus mechanisms and the cloud appeared azimuth is non-focus. At last, the shooting and bouncing ray (SBR) technique is employed to calculate the scattering of the cylinder cavity and by combining with range Doppler algorithms (RDA), the SAR image of a cylinder cavity with underside closed is precisely given, considering the effects of the multi-path scattering mechanisms in different azimuth.