**Position-Free Vital Sign Monitoring: Measurements and Processing**

Dany Obeid, Sarah Samad, Sawsan Sadek, Gheorghe Zaharia and Ghaïs El Zein

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/63915

#### **Abstract**

As traditional electrodes are perturbing for patients in critical cases such as for burn victims or newborn infants, and even to detect life sign under rubble, a contactless monitoring system for the life signs is a necessity. The aim of this chapter is to present a complete process used in detecting cardiopulmonary activities. This includes a microwave Doppler radar system that detects the body wall motion and signal processing techniques in order to extract the heartbeat rate. Measurements are performed at different positions simultaneously with a PC-based electrocardiogram (ECG). For a distance of 1 m between the subject and the antennas, measurements are performed for breathing subject at four positions: front, back, left, and right. Discrete wavelet transform is used to extract the heartbeat signal from the cardiopulmonary signal. The proposed system and signal processing techniques show high accuracy in detecting the cardiopulmonary signals and extracting the heartbeat rate.

**Keywords:** Doppler radar, cardiopulmonary signals, wavelet transforms, electrocar‐ diogram, contactless monitoring

### **1. Introduction**

Traditional electrocardiogram (ECG) with affixed electrodes could be perturbing for patients with conditions such as burn victims or newly born infants, or when long duration monitor‐ ing is needed. In addition, a monitoring system detecting life signs under rubble or snow is helpful, especially after earthquakes where the detection of life signs over long distance is needed. The utility of microwave Doppler radar used in the detection of life signs has recently in‐

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

creased. Hence, a touchless cardiopulmonary monitoring is needed for such applications and could be a prominent tool in home health care applications.

When a radio wave is transmitted toward a person, it will be reflected off his/her body. If the reflection occurs off the chest of a motionless person, the reflected signal has a phase modu‐ lation due to the Doppler effect due to the movement of the chest, which is caused mainly by heartbeats and breathing. On the other hand, when the breath is held, the reflected signal will depend on the chest displacement due to heartbeat alone.

The aim of this chapter is to present a tunable system in terms of power and frequency that shows the capability to detect chest displacement due to heart beat at different operational frequencies and for different transmitted powers. This allows specifying the appropriate operational frequency for the minimum transmitted power. In addition, simultaneously with a PC-based ECG, measurements are performed at the four different sides (front, back, left, and right) of the person under test (PUT). Wavelet transforms are used in order to separate the heartbeat signal from the cardiopulmonary signal and to extract the heartbeat rate (HR).

The rest of this chapter is organized as follows: Section 2 provides background information about chest-wall displacement. Section 3 describes related work for the system design and the signal processing technique. Section 4 presents the proposed system and some preliminary results obtained at different operational frequencies. Section 5 shows the cardiopulmonary signals obtained at different sides from the subject and presents the results upon applying the proposed signal processing technique. Section 6 concludes the work.
