High Ranging Accuracy and Wide Detection Range Interferometry Based on Frequency-Sweeping Technique with Vital Sign Sensing Function

In this paper, an interferometry-based frequency-sweeping technique has been developed and demonstrated. With this approach, the distance ambiguity problem in the traditional interferometer is solved. The relationship involving the used carrier number, noise and standing wave effects, the root-mean-square error, and the maximum unambiguous range are illustrated and discussed. The detection error caused by the noise and the standing wave effects is effectively reduced by properly increasing the used carrier number within the same bandwidth. The experiment indicates that the maximum detection error of a metal reflector detection is below 23 μm at a distance of 5 m. In addition, the vital sign sensing experiments are demonstrated. With this approach, the motion amplitude and frequency of the respiration and the heartbeats are constructed.