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Author

Yanming Xiao

Bio: Yanming Xiao is an academic researcher from University of Florida. The author has contributed to research in topics: Heartbeat & Sideband. The author has an hindex of 8, co-authored 8 publications receiving 787 citations.
Topics: Heartbeat, Sideband, Ka band, Doppler radar, Radar

Papers
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Journal ArticleDOI
TL;DR: A Ka-band transceiver using low-power double-sideband transmission to detect human heartbeat and respiration signals is demonstrated, and the detection accuracy is significantly improved with low transmitted power.
Abstract: A Ka-band transceiver using low-power double-sideband transmission to detect human heartbeat and respiration signals is demonstrated. The Ka-band electromagnetic wave offers higher detection sensitivity on small movement due to its shorter wavelength. Indirect-conversion receiver architecture is chosen to reduce the dc offset and 1/f noise that can degrade the signal-to-noise ratio and detection accuracy. Furthermore, the double-sideband signals at the transmitter output can be in quadrature by choosing a proper frequency separation to relieve the severe null point problem that occurs at high frequency. As a result,the detection accuracy is significantly improved with low transmitted power. This radar sensor system achieves better than 80% detection accuracy at a distance of 2.0 m with a combined transmitted power of only 12.5 /spl mu/W in both sidebands.

279 citations

Journal ArticleDOI
04 Dec 2006
TL;DR: In this article, the authors analyzed the harmonics observed in phase-modulated Ka-band Doppler radar, explaining the reason for better heartrate accuracy when detected from the back of the body.
Abstract: The accuracy of a Ka-band physiological movement detector was tested and compared for measurements from four different body orientations and at five different distances. A rigorous spectral analysis approach is developed when previously adopted small-angle approximation model is not applicable. This theory analyzes in detail the harmonics observed in phase-modulated Ka-band Doppler radar, explaining the reason for better heart-rate accuracy when detected from the back of the body. It also explains the advantage of double-sideband transmission in avoiding the null point problem. Simulations have been performed to illustrate this theory and provide design guidelines for the system. This theory has also been verified by experiments

237 citations

Proceedings ArticleDOI
01 Jan 2006
TL;DR: A positive answer is given to the question intrigued by the previous work: whether it is possible for a non-contact physiological movement detector to detect vital signs from four sides of a human body, and theoretical analysis confirms the surprising advantage of detection from the back of the body.
Abstract: A positive answer is given to the question intrigued by our previous work reported in EMBC 2005: whether it is possible for a non-contact physiological movement detector to detect vital signs from four sides of a human body. In addition to the proof from measured data, theoretical analysis confirms the surprising advantage of detection from the back of the body. Based on this observation, a non-contact system was set up to perform overnight monitoring of vital signs using low power radio waves. Measurement data is presented and analyzed. The challenges and key technologies that improved the performance of our system for overnight monitoring are discussed.

99 citations

Journal ArticleDOI
TL;DR: In this paper, a portable noncontact heartbeat and respiration monitoring system operating in 5GHz band is reported, which can be used for various applications in biology, medicine, and security.
Abstract: A portable noncontact heartbeat and respiration monitoring system operating in 5-GHz band is reported in this letter. Compared with the previously reported system operating at Ka-band, this system has been simplified to include only two PCB antennas, a palm-size PCB radio module, a data acquisition module, and a laptop. The system, powered by the laptop battery through USB connection, is compact, low-cost, and convenient for field test. A detection accuracy of better than 80% has been achieved at a distance of 2.8 m and at a low transmitted power of 20 muW. The system can be used for various applications in biology, medicine, and security.

87 citations

Proceedings ArticleDOI
01 Jan 2005
TL;DR: A low power Ka-band Doppler radar that can detect human heartbeat and respiration signals is demonstrated and achieves better than 80% detection accuracy at the distance of 2-m with 16-muW transmitted power.
Abstract: A low power Ka-band Doppler radar that can detect human heartbeat and respiration signals is demonstrated. This radar system achieves better than 80% detection accuracy at the distance of 2-m with 16-muW transmitted power. Indirect-conversion receiver architecture is chosen to reduce the DC offset and 1/f noise that can degrade signal-to-noise ratio and detection accuracy. In addition, the radar has also demonstrated the capability of detecting acoustic signals

81 citations


Cited by
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Journal ArticleDOI
TL;DR: This paper reviews recent advances in biomedical and healthcare applications of Doppler radar that remotely detects heartbeat and respiration of a human subject and reviews different architectures, baseband signal processing, and system implementations.
Abstract: This paper reviews recent advances in biomedical and healthcare applications of Doppler radar that remotely detects heartbeat and respiration of a human subject. In the last decade, new front-end architectures, baseband signal processing methods, and system-level integrations have been proposed by many researchers in this field to improve the detection accuracy and robustness. The advantages of noncontact detection have drawn interests in various applications, such as energy smart home, baby monitor, cardiopulmonary activity assessment, and tumor tracking. While many of the reported systems were bench-top prototypes for concept verification, several portable systems and integrated radar chips have been demonstrated. This paper reviews different architectures, baseband signal processing, and system implementations. Validations of this technology in a clinical environment will also be discussed.

625 citations

Journal ArticleDOI
TL;DR: In this article, the authors presented a method for calibrating the dc offset while preserving the dc information and capturing the motion-related signal with maximum resolution, which resulted in a significant improvement in heart rate measurement accuracy over quadrature channel selection with a standard deviation of less than 1 beat/min
Abstract: Direct-conversion microwave Doppler radar can be used to detect cardiopulmonary activity at a distance. One challenge for such detection in single channel receivers is demodulation sensitivity to target position, which can be overcome by using a quadrature receiver. This paper presents a mathematical analysis and experimental results demonstrating the effectiveness of arctangent demodulation in quadrature receivers. A particular challenge in this technique is the presence of dc offset resulting from receiver imperfections and clutter reflections, in addition to dc information related to target position and associated phase. These dc components can be large compared to the ac motion-related signal, and thus, cannot simply be included in digitization without adversely affecting resolution. Presented here is a method for calibrating the dc offset while preserving the dc information and capturing the motion-related signal with maximum resolution. Experimental results demonstrate that arctangent demodulation with dc offset compensation results in a significant improvement in heart rate measurement accuracy over quadrature channel selection, with a standard deviation of less than 1 beat/min

509 citations

Patent
03 Apr 2009
TL;DR: In this paper, a radar-based physiological motion sensor is disclosed, where Doppler-shifted signals can be extracted from the signals received by the sensor, which can be digitized and processed subsequently to extract information related to the cardiopulmonary motion in one or more subjects.
Abstract: A radar-based physiological motion sensor is disclosed. Doppler-shifted signals can be extracted from the signals received by the sensor. The Doppler-shifted signals can be digitized and processed subsequently to extract information related to the cardiopulmonary motion in one or more subjects. The information can include respiratory rates, heart rates, waveforms due to respiratory and cardiac activity, direction of arrival, abnormal or paradoxical breathing, etc. In various embodiments, the extracted information can be displayed on a display.

413 citations

Patent
01 Jun 2007
TL;DR: In this article, the motion, breathing, and heart rate signals are obtained through processing applied to a raw signal obtained in a non-contact fashion, typically using a radio-frequency sensor.
Abstract: An apparatus, system, and method monitors the motion, breathing, heart rate and sleep state of subjects, e.g., humans, in a convenient, non-invasive/non-contact, and low-cost fashion. More particularly, the motion, breathing, and heart rate signals are obtained through processing applied to a raw signal obtained in a non-contact fashion, typically using a radio-frequency sensor. Periods of sleep disturbed respiration, or central apnea can be detected through analysis of the respiratory signal. The mean heart rate, and derived information, such as the presence of cardiac arrhythmias can be determined from the cardiac signal. Motion estimates can be used to recognize disturbed sleep and periodic limb movements. The sleep state may be determined by applying a classifier model to the resulting streams of respiratory, cardiac and motion data. A means for display of the sleep state, respiratory, cardiac, and movement status may also be provided.

408 citations

Journal ArticleDOI
TL;DR: It is shown that if the dc offset of the baseband signal is accurately calibrated, both demodulation techniques can be used for random body movement cancellation in quadrature Doppler radar noncontact vital sign detection.
Abstract: The complex signal demodulation and the arctangent demodulation are studied for random body movement cancellation in quadrature Doppler radar noncontact vital sign detection. This technique can be used in sleep apnea monitor, lie detector, and baby monitor to eliminate the false alarm caused by random body movement. It is shown that if the dc offset of the baseband signal is accurately calibrated, both demodulation techniques can be used for random body movement cancellation. While the complex signal demodulation is less likely to be affected by a dc offset, the arctangent demodulation has the advantage of eliminating harmonic and intermodulation interference at high carrier frequencies. When the dc offset cannot be accurately calibrated, the complex signal demodulation is more favorable. Ray-tracing model is used to show the effects of constellation deformation and optimum/null detection ambiguity caused by the phase offset due to finite antenna directivity. Experiments have been performed using 4-7 GHz radar to verify the theory.

386 citations