Time-Domain Doppler Biomotion Detections Immune to Unavoidable DC Offsets

TL;DR

This paper introduces a novel time-domain Doppler demodulation algorithm that accurately detects bio-signals like heartbeat and pendulum movements despite unavoidable DC offsets, using PCA-assisted segmented arc approximation.

Contribution

The paper presents a new demodulation method that does not require offset elimination, improving accuracy in bio-signal detection under noisy conditions.

Findings

Successfully recovered micron-level pendulum movements.

Accurately detected human heartbeats in noisy environments.

Validated effectiveness through simulations and experiments.

Abstract

In the past decades, continuous Doppler radar sensor-based bio-signal detections have attracted many research interests. A typical example is the Doppler heartbeat detection. While significant progresses have been achieved, reliable, time-domain accurate demodulation of bio-signals in the presence of unavoidable DC offsets remains a technical challenge. Aiming to overcome this difficulty, we propose in this paper a novel demodulation algorithm that does not need to trace and eliminate dynamic DC offsets based on approximating segmented arcs in a quadrature constellation of sampling data to directional chords. Assisted by the principal component analysis, such chords and their directions can be deterministically determined. Simulations and experimental validations showed fully recovery of micron-level pendulum movements and strongly noised human heartbeats, verifying the effectiveness and accuracy of the proposed approach.