title: Data acquisition system for Doppler radar vital-sign monitor.
abstract: Automatic gain control (AGC) units increase the dynamic range of a system to compensate for the limited dynamic range of analog to digital converters. This problem is compounded in wireless systems in which large changes in signal strength are effects of a changing environment. These issues are evident in the direct-conversion Doppler radar vital-sign monitor. Utilizing microwave radar signals reflecting off a human subject, a two-channel quadrature receiver can detect periodic movement resulting from cardio-pulmonary activity. The quadrature signal is analyzed using an arctangent demodulation that extracts vital phase information. A data acquisition (DAQ) system is proposed to deal with issues inherent in arctangent demodulation of a quadrature radar signal.
authors.affiliation: University of Hawai'i at Manoa. avergara@hawaii.edu
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Vergara
authors.forename: Victor M
authors.initials: VM
authors.lastname: Lubecke
mesh_terms: D000465:Algorithms; D002319:Cardiovascular System / Q000473:pathology; D003198:Computer Simulation; D004301:Doppler Effect; D004867:Equipment Design; D006801:Humans; D008872:Microwaves; D008962:Models, Theoretical; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000379:methods; D011381:Programming Languages; D011825:Radar; D012137:Respiratory System / Q000473:pathology; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D012985:Software Design; D013997:Time Factors