Recommendation in Measuring Digital Volume Pulse for Mobile Application (Preprint)

2020 ◽  
Author(s):  
Hyeon Seok Seok ◽  
Hangsik Shin
Keyword(s):  
Health Management ◽  
Absolute Error ◽  
Sampling Frequency ◽  
Feature Point ◽  
Battery Life ◽  
Signal Acquisition ◽  
Mobile Environment ◽  
Amplitude Error ◽  
Resource Limitations ◽  
Sampled Signal

BACKGROUND As the demand to acquire bio-signals and use them for health management in daily life increases, it is becoming more common to mount photoplethysmography on mobile devices such as smartphones and smart watches. However, though it is very important to know the optimized signal measurement conditions due to resource limitations such as computing power and battery life in the mobile environment, the optimal signal acquisition conditions required to derive clinically meaningful results has not been proposed yet. OBJECTIVE This study aims to suggest appropriate criteria for measurement photoplethysmogram with clinical utility by identifying the changes in photoplethysmogram waveform with decreasing sampling frequency and quantization bit depth. METHODS Photoplethysmograms recorded at a 1-kHz sampling frequency and 16-bit quantization bit depth were converted to signals with sampling frequencies of 500-, 250-, 100-, 50-, 25-, and 10-Hz by means of down-sampling, and then we did re-quantization to convert the quantization bit depth into 16, 14, 12, 10, 8, and 6 bits for each down-sampled signal. Degradation of the signal was quantified in terms of morphological change using normalized root mean square error and feature-point deviation using mean absolute error at representative photoplethysmogram features such as pulse onset or systolic peak. RESULTS Although there were differences according to pulse onset and systolic peak, the sampling frequency of ≥ 250-Hz and 16-bit quantization bits are required in order to have ≤ 1 ms of timing error and a normalized amplitude error of ≤ 1%. In addition, a sampling frequency ≥ 100-Hz and a 12-bit quantization bits are recommended to have feature-point time errors and amplitude errors of < 10 ms and a normalized amplitude error of < 10%. CONCLUSIONS Our results highly recommend that 16-bit quantization bit depth and ≥ 250-Hz sampling to secure < 1% of error, and ≥ 25-Hz sampling and ≥ 10-bit quantization bit depth for minimal use compared with photoplethysmogram obtained by 1-kHz sampling and 16-bit quantization bit depth.

scholarly journals Low-Frequency Signal Sampling Method Implemented in a PLC Controller Dedicated to Applications in the Monitoring of Selected Electrical Devices

Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 442
Author(s):  
Marcin Jaraczewski ◽  
Ryszard Mielnik ◽  
Tomasz Gębarowski ◽  
Maciej Sułowicz
Keyword(s):  
Power System ◽  
Reactive Power ◽  
Low Frequency ◽  
Sampling Frequency ◽  
Electrical Signal ◽  
Distortion Factor ◽  
Electrical Devices ◽  
Frequency Sampling ◽  
Sampled Signal ◽  
Band Limited

High requirements for power systems, and hence for electrical devices used in industrial processes, make it necessary to ensure adequate power quality. The main parameters of the power system include the rms-values of the current, voltage, and active and reactive power consumed by the loads. In previous articles, the authors investigated the use of low-frequency sampling to measure these parameters of the power system, showing that the method can be easily implemented in simple microcontrollers and PLCs. This article discusses the methods of measuring electrical quantities by devices with low computational efficiency and low sampling frequency up to 1 kHz. It is not obvious that the signal of 50–500 Hz can be processed using the sampling frequency of fs = 47.619 Hz because it defies the Nyquist–Shannon sampling theorem. This theorem states that a reconstruction of a sampled signal is only guaranteed possible for a bandlimit fmax < fs, where fmax is the maximum frequency of a sampled signal. Therefore, theoretically, neither 50 nor 500 Hz can be identified by such a low-frequency sampling. Although, it turns out that if we have a longer period of a stable multi-harmonic signal, which is band-limited (from the bottom and top), it allows us to map this band to the lower frequencies, thus it is possible to use the lower sampling ratio and still get enough precise information of its harmonics and rms value. The use of aliasing for measurement purposes is not often used because it is considered a harmful phenomenon. In our work, it has been used for measurement purposes with good results. The main advantage of this new method is that it achieves a balance between PLC processing power (which is moderate or low) and accuracy in calculating the most important electrical signal indicators such as power, RMS value and sinusoidal-signal distortion factor (e.g., THD). It can be achieved despite an aliasing effect that causes different frequencies to become indistinguishable. The result of the research is a proposal of error reduction in the low-frequency measurement method implemented on compact PLCs. Laboratory tests carried out on a Mitsubishi FX5 compact PLC controller confirmed the correctness of the proposed method of reducing the measurement error.

scholarly journals A Health Indicator for the Online Lifetime Estimation of an Electric Vehicle Power Li-Ion Battery

2020 ◽  
Vol 11 (3) ◽  
pp. 59
Author(s):  
Bin Yu ◽  
Haifeng Qiu ◽  
Liguo Weng ◽  
Kailong Huo ◽  
Shiqi Liu ◽  
...  
Keyword(s):  
Electric Vehicle ◽  
Health Management ◽  
Estimation Error ◽  
Health Indicators ◽  
Training Data ◽  
Battery Life ◽  
Li Ion Battery ◽  
Load Curve ◽  
Response Level ◽  
Li Ion

With the further development of the electric vehicle (EV) industry, the reliability of prediction and health management (PHM) systems has received great attention. The original Li-ion battery life prediction technology developed by offline training data can no longer meet the needs of use under complex working conditions. The existing methods pay insufficient attention to the dispersive information of health indicators (HIs) under EV driving conditions, and can only calculate through standard configuration files. To solve the problem that it is difficult to directly measure the capacity loss in real time, this paper proposes a battery HI called excitation response level (ERL) to describe the voltage variation at different lifetimes, which could be easily calculated according to the current and voltage under the actual load curve. In addition, in order to further optimize the proposed HI, Box–Cox transformation was used to enhance the linear correlation between the initially extracted HI and the capacity. Several Li-ion batteries were discharged to the 50% state of health (SOH) through profiles with different depths of discharge (DODs) and mean states of charge (SOCs) to verify the accuracy and robustness of the proposed method. The average estimation error of the tested batteries was less than 3%, which shows a good performance for accuracy and robustness.

scholarly journals Development of a Wearable Reflection-Type Pulse Oximeter System to Acquire Clean PPG Signals and Measure Pulse Rate and SpO2 with and without Finger Motion

Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1905
Author(s):  
Partha Pratim Banik ◽  
Shifat Hossain ◽  
Tae-Ho Kwon ◽  
Hyoungkeun Kim ◽  
Ki-Doo Kim
Keyword(s):  
Pulse Rate ◽  
Pulse Oximeter ◽  
Electronic Circuit ◽  
Absolute Error ◽  
Motion Artifact ◽  
Motion Artifacts ◽  
Percentage Error ◽  
Signal Acquisition ◽  
Analog Filter ◽  
Finger Motion

Clinical devices play a vital role in diagnosing and monitoring people’s health. A pulse oximeter (PO) is one of the most common clinical devices for critical medical care. In this paper, we explain how we developed a wearable PO. We propose a new electronic circuit based on an analog filter that can separate red and green photoplethysmography (PPG) signals, acquire clean PPG signals, and estimate the pulse rate (PR) and peripheral capillary oxygen saturation (SpO2). We propose a PR and SpO2 measurement algorithm with and without the motion artifact. We consider three types of motion artifacts with our acquired clean PPG signal from our proposed electronic circuit. To evaluate our proposed algorithm, we measured the accuracy of our estimated SpO2 and PR. To evaluate the quality of our estimated PR (bpm) and SpO2 (%) with and without the finger motion artifact, we used the quality evaluation metrics: mean absolute percentage error (MAPE), mean absolute error (MAE), and reference closeness factor (RCF). Without the finger motion condition, we found that our proposed wearable PO device achieved an average 2.81% MAPE, 2.08 bpm MAE, 0.97 RCF, and 98.96% SpO2 accuracy. With a finger motion, the proposed wearable PO device achieved an average 4.5% MAPE, 3.66 bpm MAE, 0.96 RCF, and 96.88% SpO2 accuracy. We also show a comparison of our proposed PO device with a commercial Fingertip PO (FPO) device. We have found that our proposed PO device performs better than the commercial FPO device under finger motion conditions. To demonstrate the implementation of our wearable PO, we developed a smartphone app to allow the PO device to share PPG signals, PR, and SpO2 through Bluetooth communication. We also show the possible applications of our proposed PO as a wearable, hand-held PO device, and a PPG signal acquisition system.

scholarly journals Sub-Nyquist artefacts and sampling moiré effects

2015 ◽  
Vol 2 (3) ◽  
pp. 140550 ◽  
Author(s):  
Isaac Amidror
Keyword(s):  
Signal Processing ◽  
Low Frequency ◽  
Sampling Frequency ◽  
Signal Frequency ◽  
Periodic Signal ◽  
Unified Approach ◽  
Sampled Signal

Sampling moiré effects are well known in signal processing. They occur when a continuous periodic signal g ( x ) is sampled using a sampling frequency f s that does not respect the Nyquist condition, and the signal-frequency f folds over and gives a new, false low frequency in the sampled signal. However, some visible beating artefacts may also occur in the sampled signal when g ( x ) is sampled using a sampling frequency f s which fully respects the Nyquist condition. We call these phenomena sub-Nyquist artefacts . Although these beating effects have already been reported in the literature, their detailed mathematical behaviour is not widely known. In this paper, we study the behaviour of these phenomena and compare it with analogous results from the moiré theory. We show that both sampling moirés and sub-Nyquist artefacts obey the same basic mathematical rules, in spite of the differences between them. This leads us to a unified approach that explains all of these phenomena and puts them under the same roof. In particular, it turns out that all of these phenomena occur when the signal-frequency f and the sampling frequency f s satisfy f ≈( m / n ) f s with integer m , n , where m / n is a reduced integer ratio; cases with n =1 correspond to true sampling moiré effects.

Signal Acquisition Analysis in Hi-Speed and Hi-Precision MFL Testing for Steel Pipe

2013 ◽  
Vol 718-720 ◽  
pp. 875-880 ◽  
Author(s):  
Jian Bo Wu ◽  
Jun Tu ◽  
Yun Yang ◽  
Yi Hua Kang
Keyword(s):  
Magnetic Flux ◽  
Sampling Frequency ◽  
Magnetic Flux Leakage ◽  
Steel Pipe ◽  
Signal Frequency ◽  
Wave Form ◽  
Signal Acquisition ◽  
Sample Frequency ◽  
The Relationship ◽  
Flux Leakage

Dealing with the relationship properly between the sensor scanning and signal acquisition is the base of hi-speed and hi-precision MFL (magnetic flux leakage) testing for steel pipe. Firstly, the MFL wave form characteristic was established using magnetic dipole theory. Further, on that basis, the relationship between signal frequency and sensor scanning was analyzed. Finally, sample frequency was designed according to the requirement of the automatic steel pipe MFL testing. Additionally, the MFL signal acquisition experiment was conducted to verify the influence of the signal sampling frequency. The signal acquisition analysis was of great significant to perform the MFL testing for steel pipe in hi-speed and hi-precision.

scholarly journals Band-Pass Sampling in High-Order BOC Signal Acquisition

2018 ◽  
Vol 8 (11) ◽  
pp. 2226 ◽  
Author(s):  
Zhijun Liu ◽  
Baiyu Li ◽  
Xiangwei Zhu ◽  
Lixun Li ◽  
Guangfu Sun
Keyword(s):  
Computational Complexity ◽  
Sampling Technique ◽  
Global Navigation Satellite Systems ◽  
Signal Acquisition ◽  
Binary Offset Carrier ◽  
Satellite Systems ◽  
Sampled Signal ◽  
Band Pass ◽  
Global Navigation Satellite ◽  
High Computational Complexity

The binary offset carrier (BOC) modulation, which has been adopted in modern global navigation satellite systems (GNSS), provides a higher spectral compatibility with BPSK signals, and better tracking performance. However, the autocorrelation function (ACF) of BOC signals has multiple peaks. This feature complicates the acquisition process, since a smaller time searching step is required, which results in longer searching time or greater amounts of hardware resources. Another problem is the high Nyquist frequency, which leads to high computational complexity and power consumption. In this paper, to overcome these drawbacks, the band-pass sampling technique for multiple signals is introduced to BOC signals. The sampling frequency can be reduced significantly. Furthermore, the ACF of the sampled signal has only two secondary peaks, so that the code phase can be searched with a larger searching step. An acquisition structure base on dual-loop is proposed, to completely eliminate the ambiguity and compensate the subcarrier Doppler. The acquisition performance and the computational complexity are also analysed.

A Method of Acquiring and Processing GIC Signal in High-Speed Rail Track Circuit

2014 ◽  
Vol 1070-1072 ◽  
pp. 755-758
Author(s):  
Yun Feng Ma ◽  
Wei Zong
Keyword(s):  
High Speed ◽  
Signal Acquisition ◽  
High Speed Rail ◽  
High Speed Railway ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Rail Track ◽  
Sampled Signal ◽  
Low Pass ◽  
Track Circuit

The high-speed railway is a typical ground systems, if subjected to a larger GIC, will lead to serious incidents. For the power supply and wiring pattern of high-speed railway is different from the public grid, then how to monitor the GIC impact on the high-speed rail electrical systems need to be studied. The paper study the process and pattem of GIC in high-speed rail track circuit, and propose a signal acquisition method of GIC in the track circuit. The sampled signal will be go through the low-pass filter designed by the window function to obtain the GIC.

scholarly journals Integrated Instrumentation and Sensor Systems Enabling Condition-Based Maintenance of Aerospace Equipment

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Richard C. Millar
Keyword(s):  
Systems Engineering ◽  
Health Management ◽  
Condition Based Maintenance ◽  
System Level ◽  
Sensor Technology ◽  
Signal Acquisition ◽  
Sensor Systems ◽  
Engineering Approach ◽  
Architectural Framework ◽  
Functional Features

The objective of the work reported herein was to use a systems engineering approach to guide development of integrated instrumentation/sensor systems (IISS) incorporating communications, interconnections, and signal acquisition. These require enhanced suitability and effectiveness for diagnostics and health management of aerospace equipment governed by the principles of Condition-based maintenance (CBM). It is concluded that the systems engineering approach to IISS definition provided clear benefits in identifying overall system requirements and an architectural framework for categorizing and evaluating alternative architectures, relative to a bottom up focus on sensor technology blind to system level user needs. CBM IISS imperatives identified include factors such as tolerance of the bulk of aerospace equipment operational environments, low intrusiveness, rapid reconfiguration, and affordable life cycle costs. The functional features identified include interrogation of the variety of sensor types and interfaces common in aerospace equipment applications over multiplexed communication media with flexibility to allow rapid system reconfiguration to adapt to evolving sensor needs. This implies standardized interfaces at the sensor location (preferably to open standards), reduced wire/connector pin count in harnesses (or their elimination through use of wireless communications).

scholarly journals Learning Remotely during a Pandemic: Are Students in a Developing Country Fully Equipped with Tools for Swift Changes?

2021 ◽  
Vol 13 (15) ◽  
pp. 8635
Author(s):  
Eranda Perera ◽  
Kelum A. A. Gamage
Keyword(s):  
Online Learning ◽  
Developing Country ◽  
Rural Areas ◽  
Learning Experience ◽  
Battery Life ◽  
Face To Face ◽  
Resource Limitations ◽  
Online Mode ◽  
Higher Educational ◽  
Remote Learning

Many higher educational institutes are forced to the online mode of lecture delivery without fully understanding students’ perspectives of remote study during COVID-19, and the resource limitations of students to engage successfully in remote learning. The present study aimed to understand this gap and the students’ perspective. We collected and analysed the devices, which used by the students to connect to remote learning in a developing country. It was found that the majority of students are dependent on the laptop-smartphone combination to engage in remote learning, particularly the students in rural areas. The results highlighted the importance of smartphones in the online learning experience, considering their affordability, relatively long battery life, inbuilt internet capabilities, and portability. Although students indicated their willingness for remote learning, they clearly recognised the need for face-to-face teaching return to avoid some of the challenges and disadvantages they face as a part of remote learning.

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