Enhancement of signal quality in esophageal recordings of diaphragm EMG

1997 ◽  
Vol 82 (4) ◽  
pp. 1370-1377 ◽  
Author(s):  
Christer A. Sinderby ◽  
Jennifer C. Beck ◽  
Lars H. Lindström ◽  
Alejandro E. Grassino
Keyword(s):  
Power Spectrum ◽  
Signal To Noise Ratio ◽  
Electrode Array ◽  
Center Frequency ◽  
Signal Quality ◽  
Fiber Direction ◽  
Bipolar Electrode ◽  
Subtraction Technique ◽  
Emg Power Spectrum ◽  
Crural Diaphragm

Sinderby, Christer A., Jennifer C. Beck, Lars H. Lindström, and Alejandro E. Grassino. Enhancement of signal quality in esophageal recordings of diaphragm EMG. J. Appl. Physiol. 82(4): 1370–1377, 1997.—The crural diaphragm electromyogram (EMGdi) is recorded from a sheet of muscle, the fiber direction of which is mostly perpendicular to an esophageal bipolar electrode. The region from which the action potentials are elicited, the electrically active region of the diaphragm (EARdi) and the center of this region (EARdi ctr) may vary during voluntary contractions in terms of their position with respect to an esophageal electrode. Depending on the bipolar electrode’s position with respect to the EARdi ctr, the EMGdi is filtered to different degrees. The objectives of the present study were to reduce these filtering effects on the EMGdi by developing an analysis algorithm referred to as the “double-subtraction technique.” The results showed that changes in the position of the EARdi ctr by ±5 mm with respect to the electrode pairs located 10 mm caudal and 10 mm cephalad provided a systematic variation in the EMG power spectrum center-frequency values by ±10%. The double-subtraction technique reduced the influence of movement of the EARdi ctr relative to the electrode array on EMG power spectrum center frequency and root mean square values, increased the signal-to-noise ratio by 2 dB, and increased the number of EMG samples that were accepted by the signal quality indexes by 50%.

scholarly journals Multiple Narrowband Interferences Characterization, Detection and Mitigation Using Simplified Welch Algorithm and Notch Filtering

2021 ◽  
Vol 11 (3) ◽  
pp. 1331
Author(s):  
Mohammad Hossein Same ◽  
Gabriel Gleeton ◽  
Gabriel Gandubert ◽  
Preslav Ivanov ◽  
Rene Jr Landry
Keyword(s):  
Power Spectrum ◽  
Embedded System ◽  
Radio Frequency ◽  
Satellite Communication ◽  
Signal To Noise Ratio ◽  
Center Frequency ◽  
Infinite Impulse Response ◽  
Frequency Variation ◽  
Welch Method ◽  
The Embedded System

By increasing the demand for radio frequency (RF) and access of hackers and spoofers to low price hardware and software defined radios (SDR), radio frequency interference (RFI) became a more frequent and serious problem. In order to increase the security of satellite communication (Satcom) and guarantee the quality of service (QoS) of end users, it is crucial to detect the RFI in the desired bandwidth and protect the receiver with a proper mitigation mechanism. Digital narrowband signals are so sensitive into the interference and because of their special power spectrum shape, it is hard to detect and eliminate the RFI from their bandwidth. Thus, a proper detector requires a high precision and smooth estimation of input signal power spectral density (PSD). By utilizing the presented power spectrum by the simplified Welch method, this article proposes a solid and effective algorithm that can find all necessary interference parameters in the frequency domain while targeting practical implantation for the embedded system with minimum complexity. The proposed detector can detect several multi narrowband interferences and estimate their center frequency, bandwidth, power, start, and end of each interference individually. To remove multiple interferences, a chain of several infinite impulse response (IIR) notch filters with multiplexers is proposed. To minimize damage to the original signal, the bandwidth of each notch is adjusted in a way that maximizes the received signal to noise ratio (SNR) by the receiver. Multiple carrier wave interferences (MCWI) is utilized as a jamming attack to the Digital Video Broadcasting-Satellite-Second Generation (DVB-S2) receiver and performance of a new detector and mitigation system is investigated and validated in both simulation and practical tests. Based on the obtained results, the proposed detector can detect a weak power interference down to −25 dB and track a hopping frequency interference with center frequency variation speed up to 3 kHz. Bit error ratio (BER) performance shows 3 dB improvement by utilizing new adaptive mitigation scenario compared to non-adaptive one. Finally, the protected DVB-S2 can receive the data with SNR close to the normal situation while it is under the attack of the MCWI jammer.

Influence of bipolar esophageal electrode positioning on measurements of human crural diaphragm electromyogram

1996 ◽  
Vol 81 (3) ◽  
pp. 1434-1449 ◽  
Author(s):  
J. Beck ◽  
C. Sinderby ◽  
L. Lindstrom ◽  
A. Grassino
Keyword(s):  
Center Frequency ◽  
Esophageal Hiatus ◽  
Bipolar Electrode ◽  
Similar Data ◽  
Cross Correlation Analysis ◽  
Residual Capacity ◽  
Electrode Positioning ◽  
Time Offset ◽  
Crural Diaphragm ◽  
Voluntary Contractions

We aimed to describe how the human diaphragm electromyogram (EMGdi) is filtered at different positions within the esophageal hiatus, i.e., in the close proximity of the diaphragm, when obtained with an array of bipolar electrode pairs mounted on an esophageal catheter. We defined the electrically active crural diaphragm musculature that covers the esophagus as the electrically active region of the diaphragm (EARdi) and its center as the EARdi center. EMGdi signals were obtained via a multiple-array esophageal catheter consisting of seven sequential electrode pairs with three different electrode configurations. Subjects (n = 5) performed voluntary contractions of the diaphragm at functional residual capacity. Visual inspection of the signals revealed reversal of signal polarity on either side of the EARdi center. Extreme correlation values (r values close to -1 at 0-ms time offset) were observed for the correlation of signals on either side of the EARdi center. The root mean square (RMS) was reduced at the EARdi center; moving peripherally from the EARdi center (caudally and cephalad), the RMS increased to a peak (range of 2.1-4.1 dB for the different electrode configurations) and then decreased for the most peripheral electrode pairs. From a position where the RMS values peaked, center frequency values increased at the EARdi center (range of 26-29 Hz for the different electrode configurations). Computer simulation yielded similar data to the experimental results. We conclude that electrode positioning within the EARdi severely influences center frequency and RMS values and that the center of the EARdi can be identified via cross-correlation analysis.

Enhanced Electrochemiluminescence in the Microwell Bipolar Electrode Array Prepared with an Optical Fiber Bundle

2021 ◽  
Author(s):  
Haidong Li ◽  
Tian Zhang ◽  
Han Zhou ◽  
Zhicheng Zhang ◽  
Miaoxia Liu ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Fiber Bundle ◽  
Electrode Array ◽  
Bipolar Electrode ◽  
Optical Fiber Bundle

scholarly journals Signal quality as Achilles’ heel of graph theory in functional magnetic resonance imaging in multiple sclerosis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Johan Baijot ◽  
Stijn Denissen ◽  
Lars Costers ◽  
Jeroen Gielen ◽  
Melissa Cambron ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Signal To Noise Ratio ◽  
Pearson Correlation ◽  
Signal Quality ◽  
Network Parameters ◽  
Fmri Signal ◽  
Noise Ratio ◽  
Global And Local ◽  
The Brain ◽  
Local Brain

AbstractGraph-theoretical analysis is a novel tool to understand the organisation of the brain.We assessed whether altered graph theoretical parameters, as observed in multiple sclerosis (MS), reflect pathology-induced restructuring of the brain's functioning or result from a reduced signal quality in functional MRI (fMRI). In a cohort of 49 people with MS and a matched group of 25 healthy subjects (HS), we performed a cognitive evaluation and acquired fMRI. From the fMRI measurement, Pearson correlation-based networks were calculated and graph theoretical parameters reflecting global and local brain organisation were obtained. Additionally, we assessed metrics of scanning quality (signal to noise ratio (SNR)) and fMRI signal quality (temporal SNR and contrast to noise ratio (CNR)). In accordance with the literature, we found that the network parameters were altered in MS compared to HS. However, no significant link was found with cognition. Scanning quality (SNR) did not differ between both cohorts. In contrast, measures of fMRI signal quality were significantly different and explained the observed differences in GTA parameters. Our results suggest that differences in network parameters between MS and HS in fMRI do not reflect a functional reorganisation of the brain, but rather occur due to reduced fMRI signal quality.

Spectrum analysis of sympathetic nerve activity and blood pressure in conscious rats

1992 ◽  
Vol 263 (5) ◽  
pp. H1348-H1355 ◽  
Author(s):  
P. B. Persson ◽  
H. Stauss ◽  
O. Chung ◽  
U. Wittmann ◽  
T. Unger
Keyword(s):  
Blood Pressure ◽  
Power Spectrum ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Power Spectra ◽  
High Frequency Component ◽  
Bipolar Electrode ◽  
Phase Lag ◽  
Nerve Activity ◽  
Wistar Kyoto

This study tests whether the power spectrum of blood pressure (BP) provides information toward the sympathovagal balance of BP control by comparing the BP (femoral arterial catheter) spectrum with the spectrum of the efferent sympathetic nerve activity (SNA, bipolar electrode around splanchnic nerve). A remarkable resemblance between both spectra was found. A high-frequency component (HF) linked to respiration and a slower fluctuation type between 0.15 and 0.6 Hz (LF) were identified. There was a large and significant coherence only in the HF range of the BP and SNA power spectrum (P < 0.01). The phase lag of SNA and BP was roughly 200 ms. The recordings were repeated during pharmacological blockade in nine Wistar-Kyoto rats (WKY) and nine spontaneously hypertensive rats (SHR). alpha 1-Adrenoceptor blockade (prazosin) reduced the proportional LF power of BP in both rat strains (WKY P < 0.01, SHR P < 0.05) in favor of HF (WKY P < 0.01, SHR P < 0.01). Parasympathetic blockade (methylscopolamine) had no effect on proportions of power. Similarly, there were no significant differences in the proportional HF and LF power spectra of WKY and SHR. These data provide direct evidence for a relationship between the BP and SNA power spectra; however, only the acute changes in the sympathetic tone changed the LF-HF relationship.

scholarly journals Anti-symmetric clustering signals in the observed power spectrum

2021 ◽  
Vol 2021 (12) ◽  
pp. 003
Author(s):  
José Fonseca ◽  
Chris Clarkson
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Euler Equation ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Power Spectra ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Signal To Noise ◽  
Peculiar Velocities

Abstract In this paper, we study how to directly measure the effect of peculiar velocities in the observed angular power spectra. We do this by constructing a new anti-symmetric estimator of Large Scale Structure using different dark matter tracers. We show that the Doppler term is the major component of our estimator and we show that we can measure it with a signal-to-noise ratio up to ∼ 50 using a futuristic SKAO HI galaxy survey. We demonstrate the utility of this estimator by using it to provide constraints on the Euler equation.

scholarly journals Experimental occlusal interference and EMG power spectrum

1988 ◽  
Vol 6 ◽  
pp. 31-36
Author(s):  
Akira Hagiwara ◽  
Hideyuki Hamanaka ◽  
Yoshinori Kobayashi
Keyword(s):  
Power Spectrum ◽  
Emg Power Spectrum

scholarly journals Experimental occlusal interference and EMG power spectrum

1984 ◽  
Vol 2 ◽  
pp. 111-116
Author(s):  
Kohichi Usui ◽  
Yohsuke Itoh ◽  
Kiyohei Hayashi ◽  
Yoshinori Kobayashi
Keyword(s):  
Power Spectrum ◽  
Emg Power Spectrum

scholarly journals Determination of DVB-T2 Signal Quality in Nigeria: A Case Study of Jos, Plateau State, Nigeria

2021 ◽  
Vol 40 (1) ◽  
pp. 81-88
Author(s):  
E.E.C. Igbonoba ◽  
O. Omoifo
Keyword(s):  
Signal To Noise Ratio ◽  
Empirical Method ◽  
Signal Quality ◽  
Television System ◽  
Jos Plateau ◽  
Television Signal ◽  
Service Areas ◽  
Noise Ratio ◽  
Plateau State

This study presents the evaluation of digital video broadcasting-terrestrial second generation (DVB-T2) Television signal quality in Jos using Integrated Television Services Limited signal. The delivery of quality Television signal remains problematic in Nigeria due to signal attenuation and degradation between the transmitter and receiver station. This is primarily due to environmental and atmospheric perturbations prevalent along the signal paths. This research aim is to determine the signal quality of DVB-T2 Television system in Jos, Plateau State. The simple field measurement methodology was adopted in measuring field strength and channel power parameters. These measurement parameters were used to calculate for carrier-to-noise ratio (CNR) and signal-to-noise ratio (SNR) through empirical method. Finally, CNR and SNR were used to determine the signal quality of DVB-T2 signal in Jos. The result of the research shows that DVB-T2 signal in the primary service areas has good and reliable signal apart from the rocky environments.

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