AC coupled quadrature doppler radar displacement estimation

While cardiopulmonary rates can be estimated by various radar architectures and demodulation methods, a higher precision instrumentation is needed for accurate physiological waveform tracking and displacement estimation. It has been demonstrated that high accuracy can be achieved with DC coupled quadrature Doppler radar signal using arctangent demodulation. However, DC coupling typically increases system complexity. This paper presents a calibration of AC coupled baseband signals, to eliminate DC offset and achieve high accuracy displacement measurements without adding to radar architecture complexity.