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Proceedings Paper

Radar sensitivity to human heartbeats and respiration
Author(s): Øyvind Aardal; Sverre Brovoll; Yoann Paichard; Tor Berger; Tor Sverre Lande; Svein-Erik Hamran
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Paper Abstract

Human heartbeats and respiration can be detected from a distance using radar. This can be used for medical applications and human being detection. It is useful to have a system independent measure of how detectable the vital signs are. In radar applications, the Radar Cross Section (RCS) is normally used to characterize the detectability of an object. Since the human vital signs are seen by the radar as movements of the torso, the modulations in the person RCS can be used as a system independent measure of the vital signs detectability. In this paper, measurements of persons seated in an anechoic chamber are presented. The measurements were calibrated using empty room and a metallic calibration sphere. A narrowband radar operating at frequencies from 500 MHz to 18 GHz in discrete steps was used. A turntable provided measurements at precise aspect angles all around the person under test. In an I & Q receiver, the heartbeat and respiration modulation is a combination of amplitude and phase mod- modulations. The measurements were filtered, leaving the modulations from the vital signs in the radar recordings. The procedure for RCS computation was applied to these filtered data, capturing the complex signatures. It was found that both the heartbeat and respiration detectability increase with increasing frequency. The heartbeat signatures are almost equal from the front and the back, while being almost undetectable from the sides of the person. The respiration signatures are slightly higher from the front than from the back, and smaller from the sides. The signature measurements presented in this paper provide an objective system independent measure of the detectability of human vital signs as a function of frequency and aspect angle. These measures are useful for example in system design and in assessing real measurement scenarios.

Paper Details

Date Published: 21 May 2015
PDF: 11 pages
Proc. SPIE 9461, Radar Sensor Technology XIX; and Active and Passive Signatures VI, 946119 (21 May 2015); doi: 10.1117/12.2180924
Show Author Affiliations
Øyvind Aardal, Forsvarets forskningsinstitutt (Norway)
Sverre Brovoll, Forsvarets forskningsinstitutt (Norway)
Yoann Paichard, Forsvarets forskningsinstitutt (Norway)
Tor Berger, Forsvarets forskningsinstitutt (Norway)
Tor Sverre Lande, Univ. of Oslo (Norway)
Svein-Erik Hamran, Forsvarets forskningsinstitutt (Norway)
Univ. I Oslo (Norway)

Published in SPIE Proceedings Vol. 9461:
Radar Sensor Technology XIX; and Active and Passive Signatures VI
G. Charmaine Gilbreath; Kenneth I. Ranney; Armin Doerry; Chadwick Todd Hawley, Editor(s)

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