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Lv Q.,Zhejiang University | Dong Y.,National Key Laboratory of Science and Technology on Reactor System Design Technology | Sun Y.,Nanjing Institute of Electronic Equipment | Li C.,Texas Technology University | Ran L.,Zhejiang University
2015 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications, IMWS-BIO 2015 - Proceedings | Year: 2015

Doppler radar sensor has been widely used in non-contact bio-signal monitoring. This paper aims at recovering bio-signals from body movement. To solve the severe phase wrapping and saturation problems in large-scale body movement, as well as unwanted DC offsets and gradual changes of received microwave power problems, curve fitting technology is employed to compensate for the large-scale body movement to recover small-scale bio-signal based on a digital-IF structured, high-dynamic-range Doppler radar sensor and linearized demodulated algorithms. Experimental validations show weak bio-signal hidden in the strong body movement noise can be well extracted. © 2015 IEEE. Source


Li C.,Texas Tech University | Zhu A.,Zhejiang University | Qiao S.,Zhejiang University City College | Sun Y.,Nanjing Institute of Electronic Equipment | Ran L.,Zhejiang University
2014 Asia-Pacific Microwave Conference Proceedings, APMC 2014 | Year: 2014

This paper reports recent investigation on the possibility of human cardiac motion imaging using a continuous-wave microwave Doppler radar sensor. Compared with existing works of vital sign radar sensors that mainly focused on the heartbeat rate, the challenge is detect the actual pattern of cardiac motion. To achieve this, a DC-coupled direct conversion architecture and a digital-IF architecture can be used because both of them can avoid frequency-dependent signal distortion. A digital-IF Doppler radar sensor employing an extended differentiate and cross-multiply (DACM) algorithm was adopted to perform a series of experiments that investigate the effectiveness of noncontact cardiac imaging from different orientations of a subject. Experimental results demonstrated that in addition to detecting heartbeat rate, Doppler radar could also image one-dimensional, time domain cardiac motion that fits well with the known physiological description. Copyright 2014 IEICE. Source


Xu K.,Zhejiang University | Ye D.,Zhejiang University | Zhu Z.,National Key Laboratory of Science and Technology on Reactor System Design Technology | Huangfu J.,Zhejiang University | And 3 more authors.
IEEE Transactions on Antennas and Propagation | Year: 2015

In this paper, we present an analytical beam-forming approach capable of synthesizing differently shaped beams for circularly symmetric conformal apertures with axisymmetrical excitations. Closed form formulas of far-field radiation are mathematically derived in order to obtain rotationally symmetric radiation patterns for typical conformal apertures frequently used in satellite and flight vehicle applications, such as the cone-surfaced, truncated cone-surfaced, hybrid disc-cone and sphere-cone apertures. Based on these formulas, various shaped beams, including pencil, flat-topped and bimodal beams can be rapidly achieved by adjusting either the geometric parameters or the excitation distributions of the conformal apertures. The deterministic approach proposed in this paper provides an efficient method to synthesize specified beam shapes for the aforementioned conformal apertures. Collaborating with conventional optimization based beam forming approaches, the proposed approach can effectively shorten the time-consuming optimization in the beam forming of circularly symmetric conformal arrays, especially large conformal arrays. © 1963-2012 IEEE. Source


Xu J.,Zhejiang University | Long J.,University of California at San Diego | Sun Y.,Nanjing Institute of Electronic Equipment | Ye D.,Zhejiang University | And 4 more authors.
IEEE Radio and Wireless Symposium, RWS | Year: 2015

Remote, distance-independent phase synchronization is a challenging technology for satellite network systems, especially spaceborne bi- and multi-static SAR systems. In this paper, we focus on the theoretical description, performance analysis and experimental verification of a remote phase synchronization system implemented with spatially distributed phase loops. The derivation, simulation and experimental results show that such a system is robust when the relative movement between remote microwave systems has a constant velocity. The proposed approach can also be potentially used in multi-static satellite systems with predictable movements. © 2015 IEEE. Source


Zheng C.,Zhejiang University | Hu T.,Science and Technology on Space Microwave Laboratory | Qiao S.,Zhejiang University City College | Sun Y.,Nanjing Institute of Electronic Equipment | And 2 more authors.
2013 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications, IMWS-BIO 2013 - Proceedings | Year: 2013

Utilizing Doppler effect to detect bio-signals of vital signs has been attracting more and more interests. In this paper, we propose a time-domain algorithm for the hand gesture recognition. We introduce an extended differentiate and cross-multiply algorithm to solve the null point and the codomain restriction issues in traditional Doppler radar sensors, and retrieve the Doppler bio-signals of a moving hand from the demodulated phase signals based on a configuration of 2 or 3 radar sensors for 2-D or 3-D HGRs. Simulations validate the effectiveness of the proposed approach. Our method is capable of retrieving arbitrary hand movements, making it possible to be used in a wide range of HGR applications. © 2013 IEEE. Source

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