Sparse Nonuniform Frequency Sampling for Fast SFCW Radar Imaging

Weikang Si,Xiaodong Zhuge,Jungang Miao

doi:10.1109/access.2020.3008166

Weikang Si, Xiaodong Zhuge + Show 1 more

Open Access

https://doi.org/10.1109/access.2020.3008166

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Journal: IEEE Access	Publication Date: Jan 1, 2020
Citations: 18	License type: CC BY 4.0

Affiliation: Beihang University

Abstract

Stepped frequency continuous wave (SFCW) radar achieves wide bandwidth by synthesizing series of monochromatic pulses in a consecutive manner. Uniform frequency sampling is often performed with a constant frequency step, which in turn limits the maximum unambiguous range achievable by the radar to reliably distinguish targets. Thus, a small frequency step must be selected when clutters exist at long distances even though the target of interests is located at much closer distances. This is costly since a large number of frequencies must be synthesized, which leads to slow acquisition speed. In this paper, a sparse nonuniform frequency sampling method is proposed to effectively reduce the number of frequencies while suppressing aliasing effects from clutters. The Poisson Sum Formula is utilized to derive a deterministic formula for choosing a discrete set of frequencies within a specified frequency band. A corresponding frequency weighting formula is added in order to maintain the same target impulse response in time-domain as the one achieved by dense uniform frequency sampling. Numerical and experimental results are presented to demonstrate the improved performances of the proposed sparse sampling method for SFCW radar imaging.

Highlights

Due to large dynamic range, high phase accuracy and stable system performances, Stepped frequency continuous wave (SFCW) radar is widely used in many applications, such as through-wall radar, concealed weapon detection and non-destructive testing [1]–[5]
If an object is located outside the Maximum unambiguous range (MUR), its time-domain response will be folded inside after inverse Fourier transform (IFT) due to aliasing effects from insufficient frequency sampling
This is illustrated in Figure. 1 where objects located outside MUR appears as clutters and can

Summary

INTRODUCTION

Due to large dynamic range, high phase accuracy and stable system performances, SFCW radar is widely used in many applications, such as through-wall radar, concealed weapon detection and non-destructive testing [1]–[5]. By imposing a flat ambiguity plateau and unchanged impulse response, a weighted square-root frequency distribution can be derived based on the established method of Poisson sum formula [16]. Both numerical and measurement results illustrate that this method is effective in reducing the influence of clutters outside the maximum unambiguous range. It is effective in achieving high quality imaging with sparse frequency sampling under a complex environment.

FORMULATIONS

CONCLUSION