Method for carrying out separation and time-frequency analysis on respiration and heartbeat signals in non-contact life detection on basis of HHT (Hilbert Huang Transform)

Abstract

The invention discloses a method for carrying out separation and time-frequency analysis on respiration and heartbeat signals in non-contact life detection on the basis of HHT (Hilbert Huang Transform), which comprises the following steps of: by adopting a band-pass filter, separating the respiration and heartbeat signals and filtering out noise and harmonic waves to the greatest extent; by adopting EMD (Empirical Mode Decomposition), decomposing the filtered respiration and heartbeat signals into IMF (intrinsic mode functions) of single-frequency signals; filtering out the IMF comprising the respiration harmonic waves by adopting a maximum correlation criterion, i.e. extracting the IMF with the maximum correlation with an original signal and using the IMF as the respiration or heartbeat signal; and directly carrying out Hilbert transformation on the filtered output signal. Compared with a conventional time-frequency analysis technology, the method not only can effectively remove noise and harmonic wave interference of the respiration and heartbeat signals, but also has higher time-frequency resolution so as to effectively describe variation of life characteristics of a human body.

Description

technical field [0001] The invention relates to a signal analysis method, in particular to a method for separation and frequency analysis of breathing and heartbeat signals in non-contact life detection based on HHT. Background technique [0002] The non-contact human life detection radar uses human breathing, heartbeat movement and human limb swing to identify human targets. When the human body is still, the breathing and heartbeat movement of the human body will produce a Doppler modulation on the radar incident wave, and the Doppler signal can be processed to extract the breathing and heartbeat frequency of the human body. [0003] Such as figure 1 It is a typical continuous wave human life detector. The electromagnetic wave emitted by the radar is irradiated on the human body and reflected back. The Doppler signal reflected by the human body is amplified by the receiver and turned into a baseband signal after quadrature mixing. and heartbeat information for target ide...

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