scholarly journals Cardiopulmonary Activity Monitoring Using Millimeter Wave Radars

2020 ◽  
Vol 12 (14) ◽  
pp. 2265 ◽  
Author(s):  
Elías Antolinos ◽  
Federico García-Rial ◽  
Clara Hernández ◽  
Daniel Montesano ◽  
Juan I. Godino-Llorente ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Low Cost ◽  
Real Life ◽  
Activity Monitoring ◽  
Linear Filtering ◽  
Monitoring Tool ◽  
Current Application ◽  
Sinus Arrhythmia ◽  
Fmcw Radar ◽  
Contact Devices

Current cardiopulmonary activity monitoring is based on contact devices which cannot be used in extreme cases such as premature infants, burnt victims or rescue operations. In order to overcome these limitations, the use of radar technologies emerges as an alternative. This paper aims to enhance the comprehension that non-contact technologies, in particular radar techniques, offer as a monitoring tool. For this purpose, a modified low cost commercial 122 GHz frequency-modulated continuous-wave (FMCW) radar is used to better fit the current application domain. The radar signals obtained are processed using a classic linear filtering algorithm aiming to separate the breathing from the heartbeat component while preserving signals integrity. In a standoff configuration and with different subject orientations, results show that the signal obtained with the radar can be used to extract not only the respiratory and heartbeat rates, but also the heart rate variability (HRV) sequence. Moreover, results evidence the coupling between breathing and heartbeat, also showing that the HRV sequence obtained can identify the respiratory sinus arrhythmia (RSA) effect. Finally, the radar is tested in a simultaneous multi-target scenario, demonstrating its monitoring capabilities in more complex situations. Nevertheless, there are some challenges left to use the system in a real-life monitoring environments, such as the removal of random body movements.

Semi-Physical Simulation System for FMCW Radar

2011 ◽  
Vol 135-136 ◽  
pp. 886-892
Author(s):  
Wen Hui Chen ◽  
Xin Xi Meng ◽  
Xiao Min Liu
Keyword(s):  
Power Consumption ◽  
Low Power ◽  
Physical Simulation ◽  
Continuous Wave ◽  
Low Cost ◽  
Simulation System ◽  
Radar Signal ◽  
Low Power Consumption ◽  
Fmcw Radar ◽  
Data Process

In order to process and analyze the signal of frequency modulated continuous wave (FMCW) radar, a radar semi-physical simulation(RSPS) system based on STM32F103VE6 chip is designed in this paper. By designing the hardware and software of system, the RSPS system can process the radar signal, detect the target, verify the data process algorithm and display the result on TFT-LCD screen. In addition, the collected data can be uploaded to PC by RS-232 interfaces which improves the reliability, stability and practicability of system. The waveform and spectrum maps are utilized to show the feasibility of RSPS system in analysing FMCW radar signal. Experimental results show that this system has many advantages, such as multifunction, low power consumption and low cost.

scholarly journals Low-Complexity Super-Resolution Detection for Range-Vital Doppler Estimation FMCW Radar

2021 ◽  
Vol 21 (3) ◽  
pp. 236-245
Author(s):  
Bongseok Kim ◽  
Youngseok Jin ◽  
Youngdoo Choi ◽  
Jonghun Lee ◽  
Sangdong Kim
Keyword(s):  
Continuous Wave ◽  
Low Cost ◽  
Phase Variation ◽  
Super Resolution ◽  
Estimation Algorithm ◽  
Low Complexity ◽  
Music Algorithm ◽  
Fmcw Radar ◽  
Detection Algorithms ◽  
Simulation And Experiment

This paper proposes low-complexity super-resolution detection for range-vital Doppler estimation frequency-modulated continuous wave (FMCW) radar. In regards to vital radar, and in order to estimate joint range and vital Doppler information such as the human heartbeat and respiration, two-dimensional (2D) detection algorithms such as 2D-FFT (fast Fourier transform) and 2D-MUSIC (multiple signal classification) are required. However, due to the high complexity of 2D full-search algorithms, it is difficult to apply this process to low-cost vital FMCW systems. In this paper, we propose a method to estimate the range and vital Doppler parameters by using 1D-FFT and 1D-MUSIC algorithms, respectively. Among 1D-FFT outputs for range detection, we extract 1D-FFT results based solely on human target information with phase variation of respiration for each chirp; subsequently, the 1D-MUSIC algorithm is employed to obtain accurate vital Doppler results. By reducing the dimensions of the estimation algorithm from 2D to 1D, the computational burden is reduced. In order to verify the performance of the proposed algorithm, we compare the Monte Carlo simulation and root-mean-square error results. The simulation and experiment results show that the complexity of the proposed algorithm is significantly lower than that of an algorithm detecting signals in several regions.

scholarly journals Vital Sign Monitoring Using FMCW Radar in Various Sleeping Scenarios

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6505
Author(s):  
Emmi Turppa ◽  
Juha M. Kortelainen ◽  
Oleg Antropov ◽  
Tero Kiuru
Keyword(s):  
Heart Rate ◽  
Remote Monitoring ◽  
Vital Sign ◽  
Continuous Wave ◽  
Real Life ◽  
Vital Signs ◽  
Absolute Error ◽  
Physical Contact ◽  
Radar Signal ◽  
Fmcw Radar

Remote monitoring of vital signs for studying sleep is a user-friendly alternative to monitoring with sensors attached to the skin. For instance, remote monitoring can allow unconstrained movement during sleep, whereas detectors requiring a physical contact may detach and interrupt the measurement and affect sleep itself. This study evaluates the performance of a cost-effective frequency modulated continuous wave (FMCW) radar in remote monitoring of heart rate and respiration in scenarios resembling a set of normal and abnormal physiological conditions during sleep. We evaluate the vital signs of ten subjects in different lying positions during various tasks. Specifically, we aim for a broad range of both heart and respiration rates to replicate various real-life scenarios and to test the robustness of the selected vital sign extraction methods consisting of fast Fourier transform based cepstral and autocorrelation analyses. As compared to the reference signals obtained using Embla titanium, a certified medical device, we achieved an overall relative mean absolute error of 3.6% (86% correlation) and 9.1% (91% correlation) for the heart rate and respiration rate, respectively. Our results promote radar-based clinical monitoring by showing that the proposed radar technology and signal processing methods accurately capture even such alarming vital signs as minimal respiration. Furthermore, we show that common parameters for heart rate variability can also be accurately extracted from the radar signal, enabling further sleep analyses.

scholarly journals Educational Low-Cost C-Band FMCW Radar System Comprising Commercial Off-the-Shelf Components for Indoor Through-Wall Object Detection

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2758
Author(s):  
Hyunmin Jeong ◽  
Sangkil Kim
Keyword(s):  
Continuous Wave ◽  
Low Cost ◽  
Low Noise ◽  
Radar System ◽  
Indoor Environments ◽  
Voltage Controlled Oscillator ◽  
Band Frequency ◽  
Fmcw Radar ◽  
Sensing Applications ◽  
Commercial Off The Shelf

This paper presents an educational low-cost C-band frequency-modulated continuous wave (FMCW) radar system for use in indoor through-wall metal detection. Indoor remote-sensing applications, such as through-wall detection and positioning, are essential for the comprehensive realization of the internet of things or super-connected societies. The proposed system comprises a two-stage radio-frequency power amplifier, a voltage-controlled oscillator, circuits for frequency modulation and system synchronization, a mixer, a 3-dB power divider, a low-noise amplifier, and two cylindrical horn antennas (Tx/Rx antennas). The antenna yields gain values in the 6.8~7.8 range when operating in the 5.83~5.94 GHz frequency band. The backscattered Tx signal is sampled at 4.5 kHz using the Arduino UNO analog-to-digital converter. Thereafter, the sampled signal is transferred to the MATLAB platform and analyzed using a customized FMCW radar algorithm. The proposed system is built using commercial off-the-shelf components, and it can detect targets within a 56.3 m radius in indoor environments. In this study, the system could successfully detect targets through a 4 cm-thick ply board with a measurement accuracy of less than 10 cm.

scholarly journals Accuracy Bounds and Measurements of a Contactless Permittivity Sensor for Gases Using Synchronized Low-Cost mm-Wave Frequency Modulated Continuous Wave Radar Transceivers

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3351 ◽  
Author(s):  
Andreas Och ◽  
Jochen O. Schrattenecker ◽  
Stefan Schuster ◽  
Patrick A. Hölzl ◽  
Philipp F. Freidl ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Low Cost ◽  
Time Of Flight ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Primary Concern ◽  
Fmcw Radar ◽  
Wave Radar ◽  
Concentration Measurements ◽  
Permittivity Measurements

A primary concern in a multitude of industrial processes is the precise monitoring of gaseous substances to ensure proper operating conditions. However, many traditional technologies are not suitable for operation under harsh environmental conditions. Radar-based time-of-flight permittivity measurements have been proposed as alternative but suffer from high cost and limited accuracy in highly cluttered industrial plants. This paper examines the performance limits of low-cost frequency-modulated continuous-wave (FMCW) radar sensors for permittivity measurements. First, the accuracy limits are investigated theoretically and the Cramér-Rao lower bounds for time-of-flight based permittivity and concentration measurements are derived. In addition, Monte-Carlo simulations are carried out to validate the analytical solutions. The capabilities of the measurement concept are then demonstrated with different binary gas mixtures of Helium and Carbon Dioxide in air. A low-cost time-of-flight sensor based on two synchronized fully-integrated millimeter-wave (MMW) radar transceivers is developed and evaluated. A method to compensate systematic deviations caused by the measurement setup is proposed and implemented. The theoretical discussion underlines the necessity of exploiting the information contained in the signal phase to achieve the desired accuracy. Results of various permittivity and gas concentration measurements are in good accordance to reference sensors and measurements with a commercial vector network analyzer (VNA). In conclusion, the proposed radar-based low-cost sensor solution shows promising performance for the intended use in demanding industrial applications.

scholarly journals Detection and Classification of Multirotor Drones in Radar Sensor Networks: A Review

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4172 ◽  
Author(s):  
Angelo Coluccia ◽  
Gianluca Parisi ◽  
Alessio Fascista
Keyword(s):  
Continuous Wave ◽  
Low Cost ◽  
Weather Conditions ◽  
Surveillance Systems ◽  
Radar Sensor ◽  
Distributed Sensors ◽  
Fmcw Radar ◽  
Technological Advances ◽  
Spatially Distributed ◽  
New Generation

Thanks to recent technological advances, a new generation of low-cost, small, unmanned aerial vehicles (UAVs) is available. Small UAVs, often called drones, are enabling unprecedented applications but, at the same time, new threats are arising linked to their possible misuse (e.g., drug smuggling, terrorist attacks, espionage). In this paper, the main challenges related to the problem of drone identification are discussed, which include detection, possible verification, and classification. An overview of the most relevant technologies is provided, which in modern surveillance systems are composed into a network of spatially-distributed sensors to ensure full coverage of the monitored area. More specifically, the main focus is on the frequency modulated continuous wave (FMCW) radar sensor, which is a key technology also due to its low cost and capability to work at relatively long distances, as well as strong robustness to illumination and weather conditions. This paper provides a review of the existing literature on the most promising approaches adopted in the different phases of the identification process, i.e., detection of the possible presence of drones, target verification, and classification.

scholarly journals Motion Compensation for SAA FMCW Radar Based on Specific Switching Scheme

2019 ◽  
Vol 9 (17) ◽  
pp. 3441 ◽  
Author(s):  
Yi Lin ◽  
Tiantian Guo ◽  
Min Guo ◽  
Yunqi Fu
Keyword(s):  
Motion Compensation ◽  
Continuous Wave ◽  
Low Cost ◽  
Doa Estimation ◽  
Switching Scheme ◽  
Fmcw Radar ◽  
Measurement Results ◽  
Complex Optimization ◽  
Processing Techniques ◽  
Signal Processing Techniques

Switch antenna array (SAA) frequency modulated continuous wave (FMCW) radar has been studied by many researchers due to its low cost and straightforward architecture. However, the motion-induced phase leads to incorrect direction-of-arrival (DoA) estimation, which is one of the main obstacles when it is applied to a moving scenario. To address this problem, we propose a motion compensation method based on a specific switching scheme in this paper. The effectiveness of this method is verified by simulation and measurement results. This approach only requires basic signal processing techniques and avoids complex optimization algorithms.

scholarly journals Review article: Performance assessment of electromagnetic wave-based field sensors for SWE monitoring   

2021 ◽  
Author(s):  
Alain Royer ◽  
Alexandre Roy ◽  
Sylvain Jutras ◽  
Alexandre Langlois
Keyword(s):  
Electromagnetic Waves ◽  
Gamma Ray ◽  
Continuous Wave ◽  
Snow Water Equivalent ◽  
Low Cost ◽  
Cosmic Ray ◽  
Satellite System ◽  
Fmcw Radar ◽  
Wave Radar ◽  
Global Navigation Satellite

Abstract. Continuous and spatially distributed data of snow mass (snow water equivalent, SWE) from automatic ground-based measurements are increasingly required for climate change studies and for hydrological applications (snow hydrological model improvement and data assimilation). We present and compare four new-generation non-invasive sensors that are based on electromagnetic waves for direct measurements of SWE: Cosmic Ray Neutron Probe (CNRP); Gamma Ray Monitoring (GMON) scintillator; frequency-modulated continuous-wave radar (FMCW-Radar) at 24 GHz; and Global Navigation Satellite System (GNSS) receivers for SWE retrieval. All four techniques are relatively low cost, have low power requirements, provide continuous and autonomous measurements, and can be installed in remote areas. Their operating principles are briefly summarized before examples of comparative measurements are provided. A performance review comparing their advantages, drawbacks and accuracies is discussed. Overall instrument accuracy is estimated to range between 9 and 15 %.

scholarly journals Elimination of Motion-Induced Phase Based on Double-Time Switching Scheme for SAA FMCW Radar

Electronics ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 786 ◽  
Author(s):  
Yi Lin ◽  
Kai Yang ◽  
Min Guo ◽  
Yunqi Fu
Keyword(s):  
Continuous Wave ◽  
Low Cost ◽  
Velocity Estimation ◽  
Beam Forming ◽  
Moving Target ◽  
Switching Scheme ◽  
Time Switching ◽  
Fmcw Radar ◽  
Direction Estimation ◽  
Double Time

Due to the low cost and straightforward structure, the switch antenna array (SAA) frequency modulated continuous wave (FMCW) radar has been widely applied in many fields. However, the motion-induced phase always leads to inaccurate direction estimation of moving targets. Here, we proposed an elimination method of the motion-induced phase for the SAA FMCW radar. A double-time switching scheme (DTSS) is used for the reception of echo signals. Elimination of motion-induced phase is completed without estimating velocity, which can avoid the ambiguous velocity estimation problem. Additionally, the direction estimation of the moving target can be obtained by directly using a conventional digital beam forming (DBF) algorithm. The validity of the proposed method has been proved by the simulated and experimental results.

scholarly journals A Wideband Dielectric Waveguide-Based 160-GHz Radar Target Generator

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2801
Author(s):  
Martin Geiger ◽  
Christian Wegner ◽  
Winfried Mayer ◽  
Christian Waldschmidt
Keyword(s):  
Dielectric Waveguide ◽  
Continuous Wave ◽  
Low Cost ◽  
Radar Target ◽  
Test Procedures ◽  
Test Environment ◽  
Fmcw Radar ◽  
Radar Sensors ◽  
Full Wave ◽  
Anechoic Chambers

The increasing number of radar sensors in commercial and industrial products leads to a growing demand for system functionality tests. Conventional test procedures require expensive anechoic chambers to provide a defined test environment for radar sensors. In this paper, a compact and low cost dielectric waveguide radar target generator for level probing radars is presented. The radar target generator principle is based on a long dielectric waveguide as a one-target scenery. By manipulating the field distribution of the waveguide, a specific reflection of a radar target is generated. Two realistic scenarios for a tank level probing radar are investigated and suitable targets are designed with full wave simulations. Target distances from 13 cm to at least 9 m are realized with an extruded dielectric waveguide with dielectric losses of 2 dB/m at 160 GHz. Low loss (0.5 dB) and low reflection holders are used to fix the waveguide. Due to the dispersion of the dielectric waveguide, a detailed analysis of its impact on frequency-modulated continuous wave (FMCW) radars is given and compared to free-space propagation. The functionality of the radar target generator is verified with a 160-GHz FMCW radar prototype.

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