Calibration of gain-phase and synchronization errors for microwave staring correlated imaging with frequency-hopping waveforms

Abstract

Microwave staring correlated imaging (MSCI) is a novel super-resolution staring imaging technique based on the principle of wavefront modulation and temporal-spatial stochastic radiation field. In MSCI, accurate system parameters need to be known to establish the precise imaging model. However, as parts of the major model errors, the gain-phase and synchronization errors exist generally, which cause inaccuracies of the imaging model and defocus the imaging results. In this paper, MSCI with frequency-hopping (FH) waveforms is considered and a reference receiver is added to the MSCI system to receive the direct signal. Thus, the calibration of the errors is divided into two main stages. The first stage is concerned with estimating the gain-phase and synchronization errors using the direct FH signals, while the second stage focuses on compensating the imaging model to reconstruct the target image. Compared with the methods which jointly reconstruct the target and estimate the errors only based on the observed data at the receiver, the proposed method is easier to implement and it can be applied for broader scenarios. Simulation results are presented to demonstrate that the proposed approach can accurately estimate the gain-phase and synchronization errors and significantly improve the imaging quality.