An Improved Real-Time Echo Separation Processing Scheme in Intermediate Frequency Domain

Abstract

Space-time waveform-encoding (STWE) SAR has great potential to improve the performance of the future spaceborne SAR system. With the aim of solving the problem of overlapped echoes, one effective approach involves the use of digital beamforming (DBF) in elevation combined with the null-steering techniques. However, the traditional real-time echo separation scheme with single-null steering techniques occupies huge digital resources. In this letter, a novel real-time echo separation processing scheme in intermediate frequency domain is proposed to overcome the disadvantage of the conventional scheme. Based on the two-dimensional simulation results, the proposed scheme has the same accuracy of separating the overlapped echoes as the traditional scheme. Detailed analysis of the system complexity indicates that the proposed scheme can greatly reduce the resource occupation. Moreover, the effectiveness of the proposed scheme is further verified and demonstrated by the experimental results on the X-band 16-channel DBF-SAR system.