Multi-Target Vital-Signs Monitoring Using a Dual-Beam Phased Array Radar
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This document discusses a research paper on a dual-beam hybrid Doppler radar system designed for simultaneous monitoring of multiple vital signs, addressing challenges in current single-person monitoring systems. The system utilizes MIMO techniques and advanced beam-forming methods, significantly enhancing performance and enabling the detection of multiple subjects simultaneously. Results indicate that while the approach does not increase resolution, it effectively improves system capacity, making strides in medical applications.
Multi-Target Vital-Signs Monitoring Using a Dual-Beam Phased Array Radar
- 1. 1FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Multi-Target Vital-Signs Monitoring Using a Dual-Beam Hybrid Doppler Radar Mehrdad Nosrati1, Shahram Shahsavari2, and Negar Tavassolian1 1 Stevens Institute of Technology, Hoboken, NJ, 07030, USA 2 Tandon School of Engineering, New York University, Brooklyn, NY, 11201, USA
- 2. 2FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Outline • Introduction • Research Objective and Motivation • System Design and Analysis • Results • Conclusion
- 3. 3FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Introduction What will happen if we get a heart attack while sleeping? Critical need: Early detection to earn more response time Every 40s 800,000 deaths annually $250 B
- 4. 4FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Introduction • Doppler radars provide useful information of the target(s) such as range, velocity, and direction. Doppler Radars Applications: • Autonomous vehicles • Weather forecast • Target identification (airplanes, missiles) • Vibration monitoring (bridges, buildings) • Medical applications
- 5. 5FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Research Motivation and Objective • Problems with the current Doppler radar-based sensors: • Limited to single-person monitoring at each time • Phase Collision at the receiver ruins the signals of multiple subjects • Extremely vulnerable to the presence of other moving targets • Our Approach: • Using MIMO beam-forming techniques • Design of a multi-beam continuous wave Doppler radar
- 6. 6FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications System Design and Implementation Digital beam-forming One RF chain per antenna element Multiple beams on a shared antenna array Best performance, Most complex Hybrid beam-forming RF chains are less than antenna elements #of beams= #of RF chains Less complex lower performance
- 7. 7FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications System Design and Implementation Dual-Beam Active Phased-Array (DAPA) Doppler Radar: • Based on hybrid beam-forming technique • Generates simultaneous and independent beams
- 8. 8FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Radiation Pattern Measurements The prototype system has been tested and characterized. • Phased Shifter Calibration • Chamber Measurements • Outdoor Measurements
- 9. 9FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Radiation Pattern Measurements -100 -75 -50 -25 0 25 50 75 100 Angle, (degree) -30 -20 -10 0 NormalizedAmplitude(dB) Dual-Beam Radiation Pattern at =0 Vs Simulation Meas. Chamber Meas. Rooftop -100 -75 -50 -25 0 25 50 75 100 Angle, (degree) -30 -20 -10 0 NormalizedAmplitude(dB) Dual-Beam Radiation Pattern at =0 Vs Simulation Meas. Chamber Meas. Rooftop -100 -75 -50 -25 0 25 50 75 100 Angle, (degree) -30 -20 -10 0 NormalizedAmplitude(dB) Single Beam Radiation Pattern Directed at =0 Vs Simulation Meas. Chamber Meas. Rooftop -100 -75 -50 -25 0 25 50 75 100 Angle, (degree) -30 -20 -10 0 NormalizedAmplitude(dB) Single Beam Radiation Pattern Directed at =0 Vs Simulation Meas. Chamber Meas. Rooftop
- 10. 10FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Human Tests and Results • 4 healthy volunteers participated • 6 different groups: 4 2 = 6 Two tests for each group: 1. Single beam mode 2. Dual beam mode Group Single Beam Dual Beam 1 Fail Pass 2 Fail Pass 3 Fail Pass 4 Fail Pass 5 Fail Pass 6 Fail Pass
- 11. 11FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Human Tests and Results 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Frequency (Hz) -30 -20 -10 0 NormalizedMagnitude(dB) Output of Beam#1 Output of Beam#2 15 dB 11 dB 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Frequency (Hz) -30 -20 -10 0 NormalizedMagnitude(dB) Output of Beam#1. Frequency spectrum of the recorded signal while two subjects were monitored at the same time using the radar in dual-beam mode. 0.29 Hz 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Frequency (Hz) -30 -20 -10 0 NormalizedMagnitude(dB) Output of Beam#2. Frequency spectrum of the recorded signal while two subjects were monitored at the same time using the radar in dual-beam mode. 0.39 Hz 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Frequency (Hz) -30 -20 -10 0 NormalizedMagnitude(dB) Frequency spectrum of the recorded signal while two subjects were monitored at the same time using the radar in single-beam mode. 0.22 Hz
- 12. 12FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Summary
- 13. 13FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications • MIMO techniques can significantly improve biomedical radars performance • For the first time, we are able to monitor two subject’s vital signs simultaneously using a CW Doppler radar • The Beam-Forming approach does not increase the resolution • The Beam-Forming approach increases the system capacity Conclusion
- 14. 14FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Thank You!
- 15. 15FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications There are two solutions: 1- Range Diversity: the time of arrival of different objects is not equal Complex and costly Range ambiguity Objects at the same distance can not be differentiated 2- Space Diversity: • Beam-Switched Systems Easier to implement Only gives fixed beams • Concurrent Multi-Beam Systems (our approach) Difficult to implement Ultimate performance Differentiating more than one object? t2 t4 t3 t1
- 16. 16FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Problem Statement: Example Problem: When there are more than one person in the scene • Signals will collide and mix together Our solution: Generate multiple concurrent independent beams • Different signals can be detected
- 17. 17FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Schematic of the system Beam-forming Network System Architecture
- 18. 18FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Transmitter Specifications RF Frequency 2.0 – 2.8 GHz Antenna Ports 4 Power/Antenna Port -11.0 dBm EIRP 0 dBm Radar Mode CW Phase Shifter Yes VGA No Phase Step 1.4° Receiver Specifications RF Frequency 2.0 – 2.8 GHz Antenna Ports 4 Concurrent Beams 2 Sensitivity -80 dBm Phase Shifter Yes VGA Yes Phase Step 1.4° VGA Gain Control 30 dB System Level Specifications
- 19. 19FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications System Implementation
- 20. 20FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications System Implementation Transceiver Beam-forming network
- 21. 21FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Phased Shifter Calibration 0 45 90 135 180 225 270 315 360 Phase set-point (Degree) -10 -5 0 5 10 Phaseerror(Degree) Measured Without Calibration Measured With Calibration Table Block diagram of the calibration flow A photo of the calibration set-up The measured phase change of the DPS before and after calibration • The performance of any phased-array system depends on the phase shifter’s accuracy and precision • The digital phase shifters must be calibrated to compensate for the various errors.
- 22. 22FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Chamber Measurements
- 23. 23FR3A-2 Philadelphia, PA Student Paper Competition Finalist Sponsored by IEEE MTT-S Graduate Fellowship for Medical Applications Outdoor Measurements