The operation of microwave Doppler radar for sensing physiological motion signals is heavily compromised under sensor motion. To that end, we investigate the feasibility of applying empirical mode decomposition method in this context, and demonstrate its effectiveness in removing sensor motion artifacts. This method is shown to be effective in canceling unwanted sensor motion with precision sufficient to enable accurate heart rate extraction. Theoretical analysis and simulation results illustrate the potential of the proposed approach for a wide range of frequency separation and amplitude ratios of physiological signals and motion artifacts. Experimental results confirm that separation success is not very sensitive to amplitude ratio. A heart rate is extracted with RMSE within 1 beat per minute even in the presence of mechanical motion and order of magnitude larger in amplitude than that of the heart signal.
Cardiopulmonary signals can be detected at a distance using simple Doppler radars operating in CW mode. Tests with and without audio modulation show the feasibility of measurements with this hardware, providing a maximum measured difference to the reference of just 1.6bpm for heart rate. Tests show good correspondence of heart/respiration rate with the reference data.
Empirical Mode Decomposition has been shown effective in the analysis of non-stationary and non-linear signals. As an application in wireless life signs monitoring in this paper we use this method in conditioning the signals obtained from the Doppler device. Random physical movements, fidgeting, of the human subject during a measurement can fall on the same frequency of the heart or respiration rate and interfere with the measurement. It will be shown how Empirical Mode Decomposition can break the radar signal down into its components and help separate and remove the fidgeting interference.
Cosmic-ray muons which impinge upon the Earth's surface can be used to image the density of geological and man-made materials located above a muon detector. The detectors used for these measurements must be capable of determining the muon rate as a function of the angle of incidence. Applications of this capability include geological carbon storage, natural gas storage, enhanced oil recovery, compressed air storage, oil and gas production, tunnel detection, and detection of hidden rooms in man-made structures such as the pyramids. For these applications, the detector must be small and rugged and have operational characteristics which enable its use in remote locations, such as low power requirements. A new muon detector design is now being constructed to make measurements on the Khafre pyramid, in Egypt, to look for unknown voids that might exist in the structure. The new detector design uses monolithic plates of scintillator with wavelength-shifting fiber optic readout to obtain location information. This design will meet the operational requirements, while also providing a geometry that can be modified for different measurement conditions.
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