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Papers by Mohamed Mabrouk
IEEE transactions on bio-medical engineering, Jan 11, 2016
The use of remote sensing technologies such as radar is gaining popularity as a technique for con... more The use of remote sensing technologies such as radar is gaining popularity as a technique for contactless detection of physiological signals and analysis of human motion. This paper presents a methodology for classifying different events in a collection of phase modulated continuous wave radar returns. The primary application of interest is to monitor inmates where the presence of human vital signs amidst different interferences needs to be identified. A comprehensive set of features is derived through time and frequency domain analyses of the radar returns. The Bhattacharyya distance is used to pre-select the features with highest class separability as the possible candidate features for use in the classification process. The uncorrelated linear discriminant analysis is performed to decorrelate, denoise and reduce the dimension of the candidate feature set. Linear and quadratic Bayesian classifiers are designed to distinguish breathing, different human motions and nonhuman motions....
Fabry-Perot (F-P) interferometer was the simplest filter, in principle, used as an optical filter... more Fabry-Perot (F-P) interferometer was the simplest filter, in principle, used as an optical filter. This paper deals with using a liquid crystal-filled F-P filter to achieve a low-voltage-tunable filter with fast response and high tunable range. A mathematical model is presented and problems that may affect demanded filter specifications are discussed and their remedy is investigated. The use of the F-P filter in optical code-division multiple-access (OCDMA) to achieve the third dimension of that coding, namely the polarization coding is also discussed.
— A novel method for stand-off detection and localization of human targets behind the wall using ... more — A novel method for stand-off detection and localization of human targets behind the wall using a monostatic ultra wideband (UWB) radar is proposed. In this method, Singular Value Decomposition (SVD) and skewness are employed to achieve detection and localization. Identification of possible bins that may contain the target is done using the SVD while decision about the presence of the target in the identified bin is made using skewness. After preprocessing of the signal, skewness of the radar returns over the scans at every bin is calculated before applying this methodology. In this method, the contributions of the clutter is removed to enhance the returns from the target, by removing the dominant singular values iteratively and the range profiles over scans are reconstructed at each iteration. After each iteration, the energy in the bin over the scans is compared and the bin with maximum energy is identified as a potential target location and the previously determined skewness at this bin is compared against a precomputed data-dependent threshold. A target is declared detected if the skewness at the selected bin is lower than the threshold. The proposed method is applied on 46 measurements with a single target behind 20 cm thick gypsum wall. This method produced a 0% probability of error type I (False detection) and 4.34% error type II (missed detection) while detecting single targets. Using the same approach, it was also possible to discriminate between two targets standing 0.3 m away from each other and 3.5 m behind a 20 cm thick gypsum wall.
Human detection is an integral component of civilian and military rescue operations, military su... more Human detection is an integral component of civilian and military rescue operations, military surveillance and combat operations. Human detection can be achieved through monitoring of vital signs. In this article, a mathematical model of human breathing reflected signal received in PN-UWB radar is proposed. Unlike earlier published works, both chest and abdomen movements are considered for modeling the radar return signal along with the contributions of fundamental breathing frequency and its harmonics. Analyses of recorded reflected signals from three subjects in different postures and at different ranges from the radar indicate that ratios of the amplitudes of the harmonics contain information about posture and posture change.
Radar-based noncontact sensing of life sign signals is often used in safety and rescue missions d... more Radar-based noncontact sensing of life sign signals is often used in safety and rescue missions during disasters such as earthquakes and avalanches and for home care applications. The radar returns obtained from a human target contain the breathing frequency along with its strong higher harmonics depending on the target's posture. As a consequence, well understood, computationally efficient, and the most popular traditional FFT-based estimators that rely only on the strongest peak for estimates of breathing rates may be inaccurate. The paper proposes a solution for correcting the estimation errors of such single peak-based algorithms. The proposed method is based on using harmonically related comb filters over a set of all possible breathing frequencies. The method is tested on three subjects for different postures, for different distances between the radar and the subject, and for two different radar platforms: PN-UWB and phase modulated-CW (PM-CW) radars. Simplified algorithms more suitable for real-time implementation have also been proposed and compared using accuracy and computational complexity. The proposed breathing rate estimation algorithms provide a reduction of about 81% and 80% in the mean absolute error of breathing rates in comparison to the traditional FFT-based methods using strongest peak detection, for PN-UWB and PM-CW radars, respectively.
A method and system is described for using radar to provide non-contact detection of human breath... more A method and system is described for using radar to provide non-contact detection of human breathing at a distance. Radar data is processed to remove clutter and enable detection of a breathing signal. The breathing signal can be used to determine breathing rate or posture of the target. Static obstructions can be removed from the radar data to identify target breathing signal. The system and method can be applicable to emergency response, home or institutional monitoring applications and for detection of medical conditions
IEEE transactions on bio-medical engineering, Jan 11, 2016
The use of remote sensing technologies such as radar is gaining popularity as a technique for con... more The use of remote sensing technologies such as radar is gaining popularity as a technique for contactless detection of physiological signals and analysis of human motion. This paper presents a methodology for classifying different events in a collection of phase modulated continuous wave radar returns. The primary application of interest is to monitor inmates where the presence of human vital signs amidst different interferences needs to be identified. A comprehensive set of features is derived through time and frequency domain analyses of the radar returns. The Bhattacharyya distance is used to pre-select the features with highest class separability as the possible candidate features for use in the classification process. The uncorrelated linear discriminant analysis is performed to decorrelate, denoise and reduce the dimension of the candidate feature set. Linear and quadratic Bayesian classifiers are designed to distinguish breathing, different human motions and nonhuman motions....
Fabry-Perot (F-P) interferometer was the simplest filter, in principle, used as an optical filter... more Fabry-Perot (F-P) interferometer was the simplest filter, in principle, used as an optical filter. This paper deals with using a liquid crystal-filled F-P filter to achieve a low-voltage-tunable filter with fast response and high tunable range. A mathematical model is presented and problems that may affect demanded filter specifications are discussed and their remedy is investigated. The use of the F-P filter in optical code-division multiple-access (OCDMA) to achieve the third dimension of that coding, namely the polarization coding is also discussed.
— A novel method for stand-off detection and localization of human targets behind the wall using ... more — A novel method for stand-off detection and localization of human targets behind the wall using a monostatic ultra wideband (UWB) radar is proposed. In this method, Singular Value Decomposition (SVD) and skewness are employed to achieve detection and localization. Identification of possible bins that may contain the target is done using the SVD while decision about the presence of the target in the identified bin is made using skewness. After preprocessing of the signal, skewness of the radar returns over the scans at every bin is calculated before applying this methodology. In this method, the contributions of the clutter is removed to enhance the returns from the target, by removing the dominant singular values iteratively and the range profiles over scans are reconstructed at each iteration. After each iteration, the energy in the bin over the scans is compared and the bin with maximum energy is identified as a potential target location and the previously determined skewness at this bin is compared against a precomputed data-dependent threshold. A target is declared detected if the skewness at the selected bin is lower than the threshold. The proposed method is applied on 46 measurements with a single target behind 20 cm thick gypsum wall. This method produced a 0% probability of error type I (False detection) and 4.34% error type II (missed detection) while detecting single targets. Using the same approach, it was also possible to discriminate between two targets standing 0.3 m away from each other and 3.5 m behind a 20 cm thick gypsum wall.
Human detection is an integral component of civilian and military rescue operations, military su... more Human detection is an integral component of civilian and military rescue operations, military surveillance and combat operations. Human detection can be achieved through monitoring of vital signs. In this article, a mathematical model of human breathing reflected signal received in PN-UWB radar is proposed. Unlike earlier published works, both chest and abdomen movements are considered for modeling the radar return signal along with the contributions of fundamental breathing frequency and its harmonics. Analyses of recorded reflected signals from three subjects in different postures and at different ranges from the radar indicate that ratios of the amplitudes of the harmonics contain information about posture and posture change.
Radar-based noncontact sensing of life sign signals is often used in safety and rescue missions d... more Radar-based noncontact sensing of life sign signals is often used in safety and rescue missions during disasters such as earthquakes and avalanches and for home care applications. The radar returns obtained from a human target contain the breathing frequency along with its strong higher harmonics depending on the target's posture. As a consequence, well understood, computationally efficient, and the most popular traditional FFT-based estimators that rely only on the strongest peak for estimates of breathing rates may be inaccurate. The paper proposes a solution for correcting the estimation errors of such single peak-based algorithms. The proposed method is based on using harmonically related comb filters over a set of all possible breathing frequencies. The method is tested on three subjects for different postures, for different distances between the radar and the subject, and for two different radar platforms: PN-UWB and phase modulated-CW (PM-CW) radars. Simplified algorithms more suitable for real-time implementation have also been proposed and compared using accuracy and computational complexity. The proposed breathing rate estimation algorithms provide a reduction of about 81% and 80% in the mean absolute error of breathing rates in comparison to the traditional FFT-based methods using strongest peak detection, for PN-UWB and PM-CW radars, respectively.
A method and system is described for using radar to provide non-contact detection of human breath... more A method and system is described for using radar to provide non-contact detection of human breathing at a distance. Radar data is processed to remove clutter and enable detection of a breathing signal. The breathing signal can be used to determine breathing rate or posture of the target. Static obstructions can be removed from the radar data to identify target breathing signal. The system and method can be applicable to emergency response, home or institutional monitoring applications and for detection of medical conditions