A fast clutter cancellation method in quadrature doppler radar for noncontact vital signal detection

A fast clutter cancellation technique is proposed for quadrature Doppler radar to robustly detect the vital signals when clutters enter the test environment. The dc offset at baseband varies with the change of test environment, dramatically reducing the accuracy of vital signal detection. To solve this problem, a clutter cancellation generator is employed in the radar receiver. Based on the detected dc offset values in I and Q channels, the generator produces an output signal, anti-phase to the received clutter signal, such that the clutter signal is cancelled at RF frontend. Therefore the time-varying dc offset at baseband is eliminated. The clutter cancellation method is described and the experiment was conducted to demonstrate the proposed method.