A Joint Spatio-Temporal Sub-Nyquist Sampling Structure for Wideband Receivers

Abstract

One of the main tasks of a wideband reconnaissance receiver is to measure the carrier frequency and direction-of-arrival (DOA) rapidly once the radar signal is intercepted. To address the conflict between the wideband requirements and the Nyquist sampling theorem, a joint spatial-temporal sub-Nyquist sampling structure is developed. The parallel multiple low-rate analog-to-digital converters (ADCs) are first employed to achieve coprime sampling in the temporal domain, and the closed-form robust Chinese remainder theorem (CRT) is utilized to solve for ambiguity-free frequencies. Then, the coprime array achieves coprime sampling in the spatial domain, and its spatial spectrum completes the ambiguity-free DOA estimation due to the linear superposition of the two subarrays. To further minimize redundant samples, the coprime subarrays are matched one-to-one with the coprime ADCs so that only one ADC is connected to each antenna. Considering hypothetical physical conditions, we propose guidelines for parameter selection, including sampling rate and array arrangement. Numerical simulations demonstrate the robustness of the proposed structure and it is also effective in multisource and chirp signal scenarios.