Multi-Port Front-End and DSP
Co-Design for Vital Signs Detector
Adriana Serban (Craciunescu), Oscar Morales, Tobias Petersson, Henrik
Kalvér and Qin-Zhong Ye
Conference article, Oral presentation
Cite this conference article as:
Serban, A., Morales, O., Petersson, T., Kalvér, H., Ye, Q-Z. Multi-Port Front-End and
DSP Co-Design for Vital Signs Detector. Oral presentation at the Swedish Microwave
Days, GigaHertz Symposium, Lund, Sweden, May 24-25, 2018.
Copyright: The Authors
The self-archived postprint version of this conference article is available at Linköping
University Institutional Repository (DiVA):
http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-150613
Multi-Port Front-End and DSP Co-Design for Vital
Signs Detector
Adriana Serban1, Oscar Morales2, Tobias Pettersson3, Henrik Kalvér3, Qin-Zhong Ye1
1ITN-Communication Electronics, LiU, Campus Norrkoping, 601 74 Norrkoping 2Student, Electrical Engineering Master Programme, LiU
3Student, Electronic Design Programme, LiU
adriana.serban@liu.se
I. INTRODUCTION
Direct conversion radio applications, such as off-chip, broadband, linear and low-power quadrature modulators and demodulators using multi-port technique were inten-sively studied at Linköping University (LiU). Controlled wave interferometry within the passive multi-port (six-port) correlator with capability to accurately process phase infor-mation is also useful in microwave radar and wireless sen-sor applications [1]. In this paper, the co-design and imple-mentation of a complete hardware-software Doppler radar modular system for vital signs detection using the multi-port technology is presented [2]. In contrast to multi-port radio applications, the challenge is to demonstrate the possibility to detect weak, Hz-range frequency signals.
II. RESULTS
In Fig. 1, the principle of heartbeat and breathe rate detec-tion using continuous wave (CW) Doppler radar is illus-trated. The return signal, modulated by periodical vital signs is received and further processed by the receiver front-end (Rx) acting in conjunction with the digital signal processing (DSP) block.
A. Multi-Port Front-End Unit
The multi-port front-end unit was designed to operate at 5.8 GHz (ISM band). The antennas, the channel and the entire multi-port demodulator were modelled, designed and man-ufactured. In Fig. 2, the complete model of the front-end is shown. Thermal noise, flicker noise, and phase noise were considered during the design process due to their impact on the sensor sensitivity. For hardware-software co-design, a communication path between the multi-port microwave unit model in ADS and the DSP unit was established.
A. Digital Signal Processing Unit
A dedicated DSP unit was developed so that I- and Q raw data coming from the multi-port front-end could be used by the DSP unit to verify and optimize the algorithms and demonstrate the detectability of the vital signs. The imple-mented DSP algorithms include low-pass filtering, decima-tion, arctangent calculadecima-tion, Fast Fourier transform and peak detection, as shown in Fig. 3.
III. CONCLUSIONS
In this project, we have investigated the possibility of de-tection of low power signals at very low frequencies that emulate vital signs using the multi-port technology. The multi-port front-end was designed and first prototypes were manufactured on ROGERS4350B substrate. An appropriate digital signal processing unit was developed and imple-mented to acquire and further process the raw data coming from the front-end. It was shown that, with the existing measurement equipment, 10-Hz periodical signals could be detected.
Fig. 1. Vital signs detector system, conceptual block diagram.
Fig. 2. Multi-port front-end model in ADS.
Fig. 3. Implemented digital signal processing flow.
REFERENCES
[1] S. O. Tatu, A. Serban, M. Helaoui, A. Koelpin, ”Multiport Technology”, IEEE Microwave Magazine, vol. 15, no. 7, pp. S34-S44, 2014.
[2] Adriana Serban, Qin-Zhong Ye, “Radio and Radar Platform for Enhancing Education and Research at LiU, Campus Norrköping”, Norrköpings Fond for Forsking och Utveckling Project, 2015-2017. Tx
Antennas and Channel
Coupler
MW Multi-Port Correlator and Power Detectors
Acquisition and Digital Signal Processing
Expected Results Rx Co -d es ig n Pre-processing (Filtering Decimation) ADC ADC I Q
Acquisition Mai-loop of the DSP-kernel
DMA Memory Processing (arctan FFT) Post-processing (Peak detection) Transmitting (via Ethernet or USB) User Displaying data (on a computer/server, GUI,
every 0.5 s) Interrupt Ethernet/USB-link Pre-processing (Filtering Decimation)
