A Novel Method for Breath Detection via Stepped-Frequency Continuous Wave Ultra-Wideband (SFCW UWB) Radars Based on Operational Bandwidth Segmentation

Abstract

Human being detection via ultra-wideband (UWB) radars has shown great prospects in many areas, such as biomedicine, military operation, public security, emergency rescue, and so on. When a person stays stationary, the main feature that separates him/her from surroundings is the movement of chest wall due to breath. There have been many algorithms developed for breath detection while using UWB radars. However, those algorithms were almost based on a basic scheme that focused on processing in the time dimension of UWB data. They did not utilize the benefits from the wide operational bandwidth of UWB radars to show potential superiority over those narrowband systems such as a continuous wave (CW) Doppler radar. In this paper, a breath detection method was proposed based on operational bandwidth segmentation. A basic theoretical model was firstly introduced, indicating that characteristics of breath signals contained in UWB echoes were consistent among the operational frequencies, while those of clutters were not. So, the method divided a set of UWB echo data into a number of subsets, each of which corresponded to a sub-band within the operational bandwidth of the UWB radar. Thus information about the operational frequency is provided for subsequent processing. With the aid of the information, a breath enhancement algorithm was developed mainly by averaging the segmented UWB data along the operational frequency. The algorithm’s performance was verified by data measured by a stepped-frequency CW (SFCW) UWB radar. The experimental results showed that the algorithm performed better than that without the segmentation. They also showed its feasibility for fast detection of breath based on a short duration of data. Moreover, the method’s potential for target identification and impulse-radio (IR) UWB radar was investigated. In summary, the method provides a new processing scheme for UWB radars when they are used for breath detection. With this scheme, the UWB radars have a benefit of greater flexibility in data processing over those narrowband radars, and thus will perform more effectively and efficiently in practical applications.

Systematic Literature Review Regarding Heart Rate and Respiratory Rate Measurement by Means of Radar Technology

“…In 74 studies, both the heart rate and the respiratory rate were measured [2,5,10,12,. In 14 studies, only the respiratory rate was considered [3,11,13,[84][85][86][87][88][89][90][91][92][93][94], and in 26 studies, only the heart rate . Table 2 shows the number of acquisitions of the vital parameters considered in the experiments in relation to the radar type.…”

“…In Table 1, the titles are grouped in accordance with the radar types used, and within each category (group), they are sorted by the vital parameters measured. The number of test persons in the studies ranged from one test person [10,12,24,42,43,49,60,[85][86][87]108] to 212 test persons [98,99]. Five of the experiments were conducted with children and babies [17,45,84,88,89], eleven with miscellaneous patient groups [5,17,21,39,41,51,88,89,91,93,112] and one with animals [38], while seven experiments additionally measured a model [37,42,44,60,85,97] and two exclusively measured a model [90,92].…”

“…The test persons' positions relative to the radar were as follows: lying in 36 studies [2,3,5,13,17,23,28,29,[31][32][33][34]44,45,50,51,53,55,58,62,77,82,84,88,91,93,94,99,[104][105][106][107]110,112,114,120]; sitting in 60 studies [3,10,11,14-17,19,20,22,24,25,31,36,40,42,46-49,52-54,56,58-61,63,65,66,68-76, 78-80,83,85,86,88,89,96,97,100-103,109-111,113,117,118]; standing in 14 studies [3,21,26,27,39,57,72,76,81,87,110,113,…”

“…The distance between the test persons and the radar varied between 0.15 and 30 m. In 72 studies, measurements were performed at a distance of up to 1 m [2,5,10-14, 16-19,22,23,25-27,30,33-40, 42-45,48,51,55,57-59,61,63-65,70,74-80,80-84,86,92,93,95-97,100-103,107-111,113,115-117,120]. In 39 studies, the distance was between 1 and 10 m [3,10,15,20,24,31,32,37,44,[46][47][48][49][50]53,56,59,60,62,66,68,69,[71][72][73]76,79,81,85,87,88,90,91,93,94,109,112,115,119], and in 3 studies, it exceeded 10 m [31,49,81]. A total of 13 studies did not contain any information on the distance [21,28,41,54,…”

Detection of Breathing Movements of Preterm Neonates by Recording Their Abdominal Movements with a Time-of-Flight Camera

“…Contact-less systems include optical (time-of-flight cameras [ 54 , 55 ], stereo triangulation [ 56 , 57 ] and structured light methods [ 58 , 59 , 60 , 61 , 62 ]), radar [ 63 , 64 , 65 , 66 , 67 , 68 ], microwave [ 69 , 70 , 71 ], thermal [ 60 , 72 , 73 , 74 ] and laser [ 75 , 76 ] technologies. However, these systems have hardly been clinically tested in preterm neonates.…”