A subspace‐based channel calibration algorithm for geosynchronous satellite‐airborne bistatic multi‐channel radars

Abstract

Ground moving target indication based on geosynchronous (GEO) satellite-airborne (SA) bistatic radar can keep a certain area under continuous surveillance, and thus has important military application values. However, a channel error will affect the clutter suppression performance of the bistatic multi-channel moving target indication radar. And it is found that the channel calibration algorithm used in the long sequence monostatic side-looking synthetic aperture radar, is not applicable to the long sequence translational variant bistatic radar. An improved subspace-based channel calibration algorithm is proposed in this study to deal with channel errors of the GEO SA bistatic multi-channel radar. The algorithm utilises the clutter as calibrated sources, and estimates channel error parameters by minimising the projections of the calibrated sources onto the noise subspace. As the channel errors are estimated from the data, the proposed algorithm does not need any extra calibration sources. Also, the proposed algorithm does not have the limitation of the traditional array self-calibration algorithms, which may have non-unique estimations under the condition of linear arrays. Besides, it avoids finding the inversion of large-size matrix and calculating with any iteration, and hence it is efficient. Moreover, the proposed algorithm can estimate channel errors that vary with azimuth. Simulations are performed to validate the proposed algorithm.

Error Estimation and Unambiguous Reconstruction for Chinese First Dual-Channel Spaceborne Sar Imaging

“…The phase mismatch is estimated using the orthogonal subspace method (OSM), which has been evaluated via simulation (Zhang et al, 2010) and applied to airborne multichannel SAR systems (Zhang et al, 2015) without spaceborne application. Jin et al (2016) has shown that the OSM is an effective estimator for all scenes, with no deterioration for heterogeneous areas.…”

“…They applied correlation method to estimate the channel mismatches in DBF, with a little deficiency of not considering other estimation algorithms. The orthogonal subspace method (OSM) for error estimation was introduced by Zhang et al (2010) and Zhang et al (2015). Yang et al (2013) and Jin et al (2016) compared the OSM algorithm other methods and verified to be effective with simulated and airborne real data.…”

Antenna array calibration methods based on simultaneous perturbation

“…A variety of algorithms have been developed to calibrate antenna arrays. They are the rotating-element electric-field vector (REV) method [8][9][10], mutual coupling measurement (MCM) method [11][12][13], self-calibration method [14][15][16][17], and perturbed calibration method [18][19][20]. All these methods perform phase shift calibration in the frequency domain.…”