| Life signal detection radar can measure human life signal without contacting human body.It has good universality and can be widely used in home health detection,post disaster rescue and other fields.At present,linear frequency modulated continuous wave(LFMCW)radar for life signal detection has attracted extensive attention in the field of life signal detection because of its low power consumption and higher range resolution.In this regard,based on the establishment of LFMCW radar signal model and life signal model,this dissertation proposes two life signal extraction methods,which are based on single channel LFMCW radar life signal extraction method and multi-channel LFMCW radar life signal extraction method.The main research contents of this dissertation are as follows:Firstly,around the principle of life signal detection based on LFMCW radar,the theoretical basis of LFMCW radar and the life signal model of LFMCW radar are introduced,and the structure and advantages of the radar system used in practical measurement are explained.Then,aiming at the problem that the heartbeat signal is weak and difficult to extract,a life signal extraction method based on single channel LFMCW radar is proposed.The proposed method uses a VMD algorithm adaptively decomposes the phase signal into a specified number of eigenmode functions to realize the separation of heartbeat signal,respiratory signal,respiratory harmonic signal and stray frequency components.Combined with the modal discrimination criterion,the reconstruction of heartbeat signal and respiratory signal is realized.The experimental results show that the proposed method based on single channel LFMCW radar life signal extraction can effectively suppress the interference of harmonic and stray frequency components,and accurately extract human life signals.Finally,aiming at the problem of poor robustness of extracting life signal from single channel LFMCW radar,a life signal extraction method based on multi-channel LFMCW radar is proposed.The combining phase signal is obtained by using time division multiplexing and MRC technology,and then the human target life signal is extracted by correlation signal processing algorithm.The experimental results show that the proposed life signal extraction method based on multi-channel LFMCW radar can not only meet the accuracy of life signal extraction,but also extract human life signals more robustly. |
