A Time-varying Respiration Signal Detection Method Based on Variational Mode Decomposition

Abstract

The invention discloses a time-varying breathing signal detection method for multiple people passing through a wall based on variational mode decomposition (VMD). Received by the receiving antenna, the UWB radar echo is sampled at slow time to obtain the body echo signal matrix through the wall; the variance of each range gate is calculated by the range gate selection algorithm, and the range gate with the largest variance, that is, the existence of multiple targets, is obtained and Use a low-pass filter to eliminate high-frequency interference and redundant frequency domain components; use the VMD algorithm to perform modal decomposition on the filtered signal, iterate sub-signals, and obtain an effective breathing information that meets the number of breaths and frequency bands; perform Hilbert The time-frequency processing is performed by transformation to obtain dynamic instantaneous information including smooth breathing features. The invention can effectively eliminate interference harmonics of different breathing components, remove wall interference, enhance weak breathing signals, and has strong anti-interference and accurate time-varying tracking characteristics.

Description

technical field [0001] The invention belongs to the technical field of radar detection, in particular to a time-varying breathing signal detection method for multiple people passing through walls based on variational mode decomposition (VMD). Background technique [0002] Multi-person through-wall positioning technology is more and more applied to disaster search and rescue, anti-terrorist raids, anti-terrorism rescue and other applications, and due to the good penetration and high resolution of ultra-wideband signals, ultra-wideband radars are used to detect walls The detection of behind-the-body targets has been more and more widely recognized. There are many topics in the field of through-wall detection, such as indoor target positioning, human gait detection, and through-wall human imaging. At the same time, with the rise of biomedical technology, non- Contact through-wall vital sign detection has become an emerging topic nowadays. [0003] At this stage, the detection ...

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Problems solved by technology

However, due to the single detection method at present, it is impossible to detect dynamic tracking, and there is a lot of research space for the detection of multiple people breathing through the wall. The Fourier transform method can only detect the walking gait, and the continuous wave radar does not have strong penetration, so it is not suitable for many detection tasks in complex environments. The team of Jilin University in China uses ultra-wideband radar to detect cement Two stationary targets behind the wall are detected. However, due to the limitation of the detection accuracy of the radar used, a clear breathing waveform cannot be obtained in the actual test, and it is difficult to conduct further research.

In summary, the simple Fourier transform cannot remove low-frequency interference and respiratory harmonics, nor can it obtain the dynamic change trend of breathing, so the detection algorithm for multiple people breathing through walls based on simple frequency domain analysis has great limitations in practical applications. limitations

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