A Human Fall Detection System using Continuous Wave Radar

2019 ◽  
Vol 09 ◽  
Author(s):  
Alpesh Vala ◽  
Amit Patel ◽  
Mihir James
Keyword(s):  
High Frequency ◽  
Continuous Wave ◽  
Frequency Synthesizer ◽  
Detection System ◽  
Fall Detection ◽  
Reference Frequency ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Rf Transmitter ◽  
Wave Radar

In this paper contactless human fall detection system has been designed, developed and tested. Continuous wave radar system is implemented at 2.10 GHz of frequency. It consists of transmitter and receiver section. In radio frequency (RF) transmitter system is developed with the use of frequency synthesizer, power amplifier and patch antenna for the transmission of 2.10 GHz. Similarly at the receiver side 2.1001GHz of frequency signal is generated with the use of frequency synthesizer. For the measurement of the fall detection high frequency signal is down converted to 100 KHz of signal with the use of mixer. Number of experiment has been performed for the measurement of fall detection. Here non-living object has been used for the experimental purpose. A fall event has been detected according to the change in the received frequency in respect with the reference frequency.

scholarly journals Coherent Random-Modulated Continuous-Wave LiDAR Based on Phase-Coded Subcarrier Modulation

Photonics ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 475
Author(s):  
Zhongyang Xu ◽  
Fengxi Yu ◽  
Bowen Qiu ◽  
Yawei Zhang ◽  
Yu Xiang ◽  
...  
Keyword(s):  
High Frequency ◽  
Continuous Wave ◽  
Binary Sequence ◽  
Low Frequency ◽  
Doppler Frequency ◽  
Internal Reflection ◽  
Coherent Detection ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Balanced Photodetector

A coherent random-modulated continuous-wave (RMCW) LiDAR transmits a lightwave modulated by a pseudo-random binary sequence (PRBS). The lightwave backscattered from targets is received and used to reconstruct the PRBS. Then, the time-of-flight is extracted by correlating the reconstructed PRBS and the original PRBS. We propose a coherent RMCW LiDAR based on phase-coded subcarrier modulation, in which the impacts of internal reflection and optical Doppler frequency shift (DFS) are mitigated. A continuous lightwave is amplitude-modulated by an RF signal which is phase-coded with a PRBS. Coherent detection is used in the receiver. A beat signal that consisted of a low-frequency signal and a high-frequency signal is obtained by a single balanced photodetector (BPD). The optical DFS can be directly extracted from the low-frequency signal. It is used to compensate for the frequency offset of PRBS, which is extracted from the high-frequency signal. In addition, the background noise caused by internal reflection is suppressed by averaging over successive measurement spots. In this paper, the performance of a coherent RMCW LiDAR is firstly analyzed by numeric simulations and demonstration experiments. Then, line-scanning measurements for moving targets are implemented to demonstrate the 3D imaging capability of the proposed coherent RMCW LiDAR.

Dither in a rolling airframe flight vehicle with a two-position actuator: An amplitude distribution approach

2016 ◽  
Vol 39 (8) ◽  
pp. 1205-1215 ◽  
Author(s):  
Bahram Mohammadi ◽  
Mohammad Reza Arvan ◽  
Yousof Koohmaskan
Keyword(s):  
High Frequency ◽  
Degrees Of Freedom ◽  
Coupling Effect ◽  
Cross Coupling ◽  
Amplitude Distribution ◽  
Feedback System ◽  
Flight Vehicle ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Minimal Error

Rolling airframe manoeuvring is a type of manoeuvre in which the missile provides continuous roll during flight. Cross-coupling between the angle of attack and sideslip in rolling airframe missiles (RAMs) yields a coning motion around the flight path. As the pitch and yaw cross-coupling effect decreases, the radius of this coning motion decreases and the accuracy of the control system increases. Two-position (on–off) actuators are used in most RAMs. The presence of a two-position actuator in a feedback system makes its characteristics non-linear. A high-frequency signal so-called dither is applied to compensate for the non-linearity effect of the actuator characteristic in the feedback system and to stabilize the coning motion. The amplitude distribution function (ADF) method in dither analysis shows that the smoothed non-linearity characteristic can be computed as the convolution of the original non-linearity and the ADF of the dither signal. According to the four-degrees-of-freedom (4-DOF) equations of RAMs in a non-rolling frame and regarding various dither signals through the ADF approach on a two-position actuator, an analytical condition for dither amplitude in coning motion stability of RAMs is derived. It was shown that the triangular signal with specified amplitude and high enough frequency led to a smoother response of two-position actuators. Finally, by applying beam-riding guidance to a RAM, the performance of dithers for decreasing the distance of the missile from the centre of the beam is validated through simulations. It is illustrated that applying the triangular dither resulted in minimal error.

Fall Detection via Inaudible Acoustic Sensing

2021 ◽  
Vol 5 (3) ◽  
pp. 1-21
Author(s):  
Jie Lian ◽  
Xu Yuan ◽  
Ming Li ◽  
Nian-Feng Tzeng
Keyword(s):  
Continuous Wave ◽  
Detection System ◽  
Fall Detection ◽  
Superior Performance ◽  
Medical Assistance ◽  
Acoustic Sensing ◽  
Value Decomposition ◽  
Human Motions ◽  
Audio Device ◽  
Fall Accidents

The fall detection system is of critical importance in protecting elders through promptly discovering fall accidents to provide immediate medical assistance, potentially saving elders' lives. This paper aims to develop a novel and lightweight fall detection system by relying solely on a home audio device via inaudible acoustic sensing, to recognize fall occurrences for wide home deployment. In particular, we program the audio device to let its speaker emit 20kHz continuous wave, while utilizing a microphone to record reflected signals for capturing the Doppler shift caused by the fall. Considering interferences from different factors, we first develop a set of solutions for their removal to get clean spectrograms and then apply the power burst curve to locate the time points at which human motions happen. A set of effective features is then extracted from the spectrograms for representing the fall patterns, distinguishable from normal activities. We further apply the Singular Value Decomposition (SVD) and K-mean algorithms to reduce the data feature dimensions and to cluster the data, respectively, before input them to a Hidden Markov Model for training and classification. In the end, our system is implemented and deployed in various environments for evaluation. The experimental results demonstrate that our system can achieve superior performance for detecting fall accidents and is robust to environment changes, i.e., transferable to other environments after training in one environment.

scholarly journals An Investigation into Error Source Identification of Machine Tools Based on Time-Frequency Feature Extraction

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Dongju Chen ◽  
Shuai Zhou ◽  
Lihua Dong ◽  
Jinwei Fan
Keyword(s):  
Machine Tool ◽  
Frequency Domain ◽  
Surface Topography ◽  
High Frequency ◽  
Low Frequency ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Time Frequency ◽  
Cross Correlation Analysis ◽  
Correlation Analysis Method

This paper presents a new identification method to identify the main errors of the machine tool in time-frequency domain. The low- and high-frequency signals of the workpiece surface are decomposed based on the Daubechies wavelet transform. With power spectral density analysis, the main features of the high-frequency signal corresponding to the imbalance of the spindle system are extracted from the surface topography of the workpiece in the frequency domain. With the cross-correlation analysis method, the relationship between the guideway error of the machine tool and the low-frequency signal of the surface topography is calculated in the time domain.

Magnet Temperature Estimation in Surface PM Machines Using High-Frequency Signal Injection

2010 ◽  
Vol 46 (4) ◽  
pp. 1468-1475 ◽  
Author(s):  
David Díaz Reigosa ◽  
Fernando Briz ◽  
Pablo García ◽  
Juan Manuel Guerrero ◽  
Michael W Degner
Keyword(s):  
High Frequency ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Temperature Estimation ◽  
Signal Injection
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