Heart Rate Measurement Based on Event Timing Coding Observed by Video Camera

Takashi G. SATO  Yoshifumi SHIRAKI  Takehiro MORIYA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E100-B   No.6   pp.926-931
Publication Date: 2017/06/01
Online ISSN: 1745-1345
Type of Manuscript: Special Section PAPER (Special Section on Visible Light Communications in Conjunction with Topics of ICEVLC 2015)
Category: Sensing
Keyword: 
image sensor,  event timing,  heart rate,  free space optical communication,  interval data transfer,  

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Summary: 
The purpose of this study was to examine an efficient interval encoding method with a slow-frame-rate image sensor, and show that the encoding can work to capture heart rates from multiple persons. Visible light communication (VLC) with an image sensor is a powerful method for obtaining data from sensors distributed in the field with their positional information. However, the capturing speed of the camera is usually not fast enough to transfer interval information like the heart rate. To overcome this problem, we have developed an event timing (ET) encoding method. In ET encoding, sensor units detect the occurrence of heart beat event and send their timing through a sequence of flashing lights. The first flash signal provides the rough timing and subsequent signals give the precise timing. Our theoretical analysis shows that in most cases the ET encoding method performs better than simple encoding methods. Heart rate transfer from multiple persons was examined as an example of the method's capabilities. In the experimental setup, the developed system successfully monitored heart rates from several participants.