Tomographic radar imaging using frame theory

Image of a target, which is reconstructed using the return pulses of an inverse synthetic aperture radar (ISAR), can be thought as a vector in a Hilbert space spanned by a frame. In such a vector space, a target image is simply the projection of target returned signals onto the frame. In this paper, a frame processing (FP) method for ISAR imaging is proposed. We show that a dual frame of the target image vector space can be constructed from knowledge of radar parameters and target motion. The image of target can then be reconstructed by the inner product of radar returns and the dual frame. As an alternative to the existing fast Fourier transform (FFT) based approaches, the proposed FP method for ISAR imaging does not suffer from the range walk which is a critical issue associated with FFT based approaches in the ISAR imaging when a long signal sequence is considered to increase the synthetic aperture as to capture more target information. Simulated and experimental results are presented to demonstrate the effectiveness of the proposed method.