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A Method for Remotely Sensing Vital Signs of Human Subjects Outdoors.

Li C, Chen F, Jin J, Lv H, Li S, Lu G, Wang J - Sensors (Basel) (2015)

Bottom Line: Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way.Finally, the detection capabilities of the radar system and the signal processing method are verified through experiments which show that human respiration signals can be extracted when the subject is 7 m away outdoors.The method provided in this paper will be a promising way to search for human subjects outdoors.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China. lichuantao614@126.com.

ABSTRACT
After chemical or nuclear leakage or explosions, finding survivors is a huge challenge. Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way. This paper describes a continuous wave radar sensor for remotely sensing the vital signs of human subjects. Firstly, a compact and portable 24 GHz Doppler radar system is designed to conduct non-contact detection of respiration signal. Secondly, in order to improve the quality of the respiration signals, the self-correlation and adaptive line enhancer (ALE) methods are proposed to minimize the interferences of any moving objects around the human subject. Finally, the detection capabilities of the radar system and the signal processing method are verified through experiments which show that human respiration signals can be extracted when the subject is 7 m away outdoors. The method provided in this paper will be a promising way to search for human subjects outdoors.

No MeSH data available.


Related in: MedlinePlus

CW radar sensor system. (a) Block diagram of the 24 GHz radar respiration sensor system; (b) Photograph of the 24 GHz respiration radar sensor system.
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sensors-15-14830-f001: CW radar sensor system. (a) Block diagram of the 24 GHz radar respiration sensor system; (b) Photograph of the 24 GHz respiration radar sensor system.

Mentions: A low-pass filter can be used for eliminating the 24 GHz carrier signal. In the low-frequency parts, it is mainly the breathing x(t) that causes the change of phase position. A low-frequency radar produces in a small phase variation while a high-frequency radar results in a large phase variation. High frequency can reduce the radar antenna size, but high radar frequency leads to strong directivity, which makes the radar alignment difficult during the breathing measurements [12]. Considering the precision and detection scope comprehensively, the 24 GHz radar is selected as shown in Figure 1. The wave length of a 24 GHz radar is 12.5 mm, and the radar can cover 60° in the vertical direction, with a horizontal defensive line covering 160°. It is reported that the chest displacement caused by breathing can result in a 230.4°–691.2° phase change of the 24 GHz continuous radar signal.


A Method for Remotely Sensing Vital Signs of Human Subjects Outdoors.

Li C, Chen F, Jin J, Lv H, Li S, Lu G, Wang J - Sensors (Basel) (2015)

CW radar sensor system. (a) Block diagram of the 24 GHz radar respiration sensor system; (b) Photograph of the 24 GHz respiration radar sensor system.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541809&req=5

sensors-15-14830-f001: CW radar sensor system. (a) Block diagram of the 24 GHz radar respiration sensor system; (b) Photograph of the 24 GHz respiration radar sensor system.
Mentions: A low-pass filter can be used for eliminating the 24 GHz carrier signal. In the low-frequency parts, it is mainly the breathing x(t) that causes the change of phase position. A low-frequency radar produces in a small phase variation while a high-frequency radar results in a large phase variation. High frequency can reduce the radar antenna size, but high radar frequency leads to strong directivity, which makes the radar alignment difficult during the breathing measurements [12]. Considering the precision and detection scope comprehensively, the 24 GHz radar is selected as shown in Figure 1. The wave length of a 24 GHz radar is 12.5 mm, and the radar can cover 60° in the vertical direction, with a horizontal defensive line covering 160°. It is reported that the chest displacement caused by breathing can result in a 230.4°–691.2° phase change of the 24 GHz continuous radar signal.

Bottom Line: Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way.Finally, the detection capabilities of the radar system and the signal processing method are verified through experiments which show that human respiration signals can be extracted when the subject is 7 m away outdoors.The method provided in this paper will be a promising way to search for human subjects outdoors.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China. lichuantao614@126.com.

ABSTRACT
After chemical or nuclear leakage or explosions, finding survivors is a huge challenge. Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way. This paper describes a continuous wave radar sensor for remotely sensing the vital signs of human subjects. Firstly, a compact and portable 24 GHz Doppler radar system is designed to conduct non-contact detection of respiration signal. Secondly, in order to improve the quality of the respiration signals, the self-correlation and adaptive line enhancer (ALE) methods are proposed to minimize the interferences of any moving objects around the human subject. Finally, the detection capabilities of the radar system and the signal processing method are verified through experiments which show that human respiration signals can be extracted when the subject is 7 m away outdoors. The method provided in this paper will be a promising way to search for human subjects outdoors.

No MeSH data available.


Related in: MedlinePlus