On the Slow-Time k-Space and its Augmentation in Doppler Radar Tomography

Abstract

Doppler Radar Tomography (DRT) relies on spatial diversity from rotational motion of a target rather than spectral diversity from wide bandwidth signals. The slow-time k-space is a novel form of the spatial frequency space generated by the relative rotational motion of a target at a single radar frequency, which can be exploited for high-resolution target imaging by a narrowband radar with Doppler tomographic signal processing. This paper builds on a previously published work and demonstrates, with real experimental data, a unique and interesting characteristic of the slow-time k-space: it can be augmented and significantly enhance imaging resolution by signal processing. High resolution can reveal finer details in the image, providing more information to identify unknown targets detected by the radar.

Micro-Doppler Signature Analysis for Space Domain Awareness Using VHF Radar

“…Typically, the radar cross section is extracted from electromagnetic simulations; however, Doppler information can be provided if a common phase centre is defined across the angular samples for the electric field calculations. Doppler information can be retrieved from angular samples equivalently to time samples [32], which effectively creates an angular sampling rate conversion of PRF a = PRF/ω in samples/radian [33]. In practice, the angular sampling rate is defined as the total number of angular samples, divided by the maximum angular extent.…”

“…The resolution of the spectrogram is constrained by three factors based on the Doppler ambiguity condition, the linear approximation of the Fourier transform and the Doppler migration condition [33]. The Doppler migration condition ∆Θ DM is inversely proportional to the electrical size (2r/λ) of the resident space object and determines the angular bin size used in the spectrogram.…”