DC-Independent High-Linear Motion Sensing Based on a Novel ACAA Algorithm

Abstract

The continuous-wave (CW) radar is subject to the dc offsets issue and the phase ambiguity issue in displacement motion sensing. This letter proposes a novel adjacent chord angle accumulation (ACAA) algorithm to realize dc-independent and high-linear phase demodulation in motion sensing with CW radars. It works by accumulating the angles of the adjacent chords of the <inline-formula> <tex-math notation="LaTeX">$I/Q$ </tex-math></inline-formula> trajectory. The angle of the adjacent chord is unrelated to the circle center of the <inline-formula> <tex-math notation="LaTeX">$I/Q$ </tex-math></inline-formula> trajectory, which makes the algorithm immune to the dc offsets. Moreover, the accumulation of the small angle of each step makes the algorithm immune to phase ambiguity. The theory and working principles are presented. Simulations and experiments show that the algorithm can work well under dc offsets that are even larger than the signal itself and can precisely extract displacement motions as large as four times the wavelength without phase ambiguity.