CW and Pulse–Doppler Radar Processing Based on FPGA for Human Sensing Applications

TLDR

CW Doppler radar offers low‑cost single‑human activity monitoring without range, while UWB pulse‑Doppler radar provides high‑resolution through‑wall sensing, multi‑object detection, and real‑time tracking with micro‑Doppler signatures. The paper aims to evaluate FPGA‑based processing of time‑ and frequency‑domain signals for human‑sensing radar, addressing design challenges, performance, and trade‑offs. The authors implement FPGA‑based signal processing, featuring a superheterodyne receiver with digital downconversion for CW Doppler radar and an equivalent‑time sampling scheme for UWB pulse‑Doppler radar to achieve low‑noise, narrow‑pulse digitization. Both radar prototypes were successfully realized with highly integrated, compact FPGA‑based data acquisition hardware.

Abstract

In this paper, we discuss using field-programmable gate arrays (FPGAs) to process either time- or frequency-domain signals in human sensing radar applications. One example will be given for a continuous-wave (CW) Doppler radar and another for an ultrawideband (UWB) pulse–Doppler (PD) radar. The example for the CW Doppler radar utilizes a novel superheterodyne receiver to suppress low-frequency noise and includes a digital downconverter module implemented in an FPGA. Meanwhile, the UWB PD radar employs a carrier-based transceiver and a novel equivalent time sampling scheme based on FPGA for narrow pulse digitization. Highly integrated compact data acquisition hardware has been implemented and exploited in both radar prototypes. Typically, the CW Doppler radar is a low-cost option for single human activity monitoring, vital sign detection, etc., where target range information is not required. Meanwhile, the UWB PD radar is more advanced in through-wall sensing, multiple-object detection, real-time target tracking, and so on, where a high-resolution range profile is acquired together with a micro-Doppler signature. Design challenges, performance comparison, pros, and cons will be discussed in detail.