scholarly journals Electromagnetic Shielding Performance Measurement for Braided-Shield Power Cables at Low Frequency Regimes

2020 ◽  
Vol 20 (5) ◽  
pp. 224-229
Author(s):  
Zhongyuan Zhou ◽  
Peng Hu ◽  
Xiang Zhou ◽  
Mingjie Sheng ◽  
Peng Li ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Measurement Techniques ◽  
Low Frequency ◽  
Reduction Factor ◽  
Electromagnetic Shielding ◽  
Power Cables ◽  
Transfer Impedance ◽  
Factor Method ◽  
Definition Of ◽  
Ground Loop

AbstractAlthough various measurement techniques have been applied to both qualitative and quantitative evaluation for the electromagnetic shielding performance of braided-shield power cables, the existing measurements cannot directly assess the low-frequency shielding performance (typically below 100 kHz) due to factors such as ground-loop effects and dynamic range problem in measurement. To solve these, an improved shield reduction factor method, based on gain (T/R) rather than scattering parameters, is proposed to evaluate the shielding performance of braided-shield power cables from 25 Hz to 1 MHz. In this work, we highlight the implementation of measurement setup to avoid the effects of ground-loop and stray electromagnetic field. Meanwhile, the test cell is simplified according to the definition of the shield reduction factor in order to obtain the gain (T/R) parameters, which can be used to calculate transfer impedance as well. From the measurements we present more intuitive evaluation of shielding behavior of braided-shield power cables at low frequency regimes, and showcase a detailed comparative discussion between transfer impedance and shield reduction factor. The proposed shield reduction factor method is expected to be a useful way for the evaluation of the low frequency shielding performance of braided-shield cables.

scholarly journals Measurement Techniques for Electromagnetic Shielding Behavior of Braided-Shield Power Cables: An Overview and Comparative Study

2019 ◽  
Vol 19 (5) ◽  
pp. 213-221
Author(s):  
Peng Hu ◽  
Zhongyuan Zhou ◽  
Jinpeng Li ◽  
Xiang Zhou ◽  
Mingjie Sheng ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Equivalent Circuit Model ◽  
Qualitative Evaluation ◽  
Reduction Factor ◽  
Power Cables ◽  
Testing Methods ◽  
Transfer Impedance ◽  
Impedance Testing ◽  
Overview Analysis ◽  
Symmetrical Communication

Abstract More and more EMC tests have shown that the radiated emission problems of the equipment under test mainly concentrate on the intercon- nected power cables and cable connectors. Measurement of shielding performance is a prerequisite for quantitative and qualitative evaluation of the frequency-dependent characteristic of braided-shield power cables and cable connectors. Due to the asymmetric geometric structures of these cable assemblies, compared with the coaxial and symmetrical communication cables, the commonly used transfer impedance testing methods may not be suitable. In view of this, several improved simple and effective measurement methods, including transfer impedance and shield reduction factor testing methods, were proposed in recent years. These methods, based on the equivalent circuit model of the characteristic parameters, provide good repeatability for the measurement of shielding performance. This paper presents an overview analysis of various measurement techniques for shielding performance of power cables and cable connectors, highlights some of its equivalence principle in measurement setups, and showcases a brief comparison between transfer impedance and shield reduction factor.

Noise Modeling and Characterization of Piezoresistive Transducers

2006 ◽  
Author(s):  
Toshikazu Nishida ◽  
Robert Dieme ◽  
Mark Sheplak ◽  
Gijs Bosman
Keyword(s):  
Dynamic Range ◽  
Measurement Techniques ◽  
Low Frequency ◽  
Noise Model ◽  
Noise Modeling ◽  
Mems Microphone ◽  
Output Noise ◽  
Noise Measurements ◽  
Transducer Output

This paper presents detailed results on noise modeling and experimental characterization applicable to piezoresistive MEMS transducers using a piezoresistive MEMS microphone as an example. To accurately model the lower limit of the dynamic range of piezoresistive MEMS transducers, a detailed noise equivalent circuit, piezoresistor noise model, and experimental noise measurements are needed. From the sensitivity and the total root-mean-square output noise, the minimum detectable signal (MDS) may be computed. Key experimental results include comparison of the DC bridge and AC bridge noise measurement techniques and use of the AC measurement technique when the piezoresistive transducer output noise is less than the low frequency DC setup noise.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

Preamplifier With Ultra Low Frequency Cutoff for Infrasonic Condenser Microphone

2012 ◽  
Author(s):  
Rasmus Trock Kinnerup ◽  
Arnold Knott ◽  
Ole Cornelius Thomsen ◽  
Kresten Marbjerg ◽  
Per Rasmussen
Keyword(s):  
Input Impedance ◽  
Dynamic Range ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Input Resistance ◽  
Bias Current ◽  
Microphone Signal ◽  
Low Frequencies ◽  
Pass Filter ◽  
Condenser Microphone

Measuring infrasonic sound sets high requirements on the instruments used. Typically the measurement chain consists of a microphone and a preamplifier. As the input resistance of the preamplifier forms a high pass filter with the capacitance of the microphone in the picofarad range, measuring ultra low frequencies becomes a challenge. The electric preamplifier presented in this paper together with a prepolarized condenser microphone form a measurement system. The developed preamplifier connects the microphone signal directly to the input of an operational amplifier with ultra high input impedance. The bias current for the preamplifier further complicates the signal amplification. A configuration of two diode-connected FETs provide the input bias current. The resulting input impedance of nearly 1 TΩ yields a total lower limiting −3 dB cutoff frequency of 8 mHz and a dynamic range of 95 dB. Being able to measure down to ultra low frequencies in the infrasonic frequency range will aid actors in the debate on wind turbine noise. Sonic booms from supersonic flights include frequencies down to 10 mHz and the preamplifier proposed in this paper will aid scientists trying to modify the N-shaped shock wave at high level which prohibits flights in land zones.

scholarly journals Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization

2011 ◽  
Vol 28 (1) ◽  
pp. 46-57 ◽  
Author(s):  
B. Pindor ◽  
J. S. B. Wyithe ◽  
D. A. Mitchell ◽  
S. M. Ord ◽  
R. B. Wayth ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Dynamic Range ◽  
Low Frequency ◽  
Neutral Hydrogen ◽  
Galactic Nuclei ◽  
Point Sources ◽  
Field Of View ◽  
Bright Point ◽  
Line Of Sight ◽  
Diffuse Background

AbstractBright point sources associated with extragalactic active galactic nuclei and radio galaxies are an important foreground for low-frequency radio experiments aimed at detecting the redshifted 21-cm emission from neutral hydrogen during the epoch of reionization. The frequency dependence of the synthesized beam implies that the sidelobes of these sources will move across the field of view as a function of observing frequency, hence frustrating line-of-sight foreground subtraction techniques. We describe a method for subtracting these point sources from dirty maps produced by an instrument such as the MWA. This technique combines matched filters with an iterative centroiding scheme to locate and characterize point sources in the presence of a diffuse background. Simulations show that this technique can improve the dynamic range of epoch-of-reionization maps by 2—3 orders of magnitude.

scholarly journals Ladder-Based Synthesis and Design of Low-Frequency Buffer-Based CMOS Filters

Electronics ◽  
2021 ◽  
Vol 10 (23) ◽  
pp. 2931
Author(s):  
Waldemar Jendernalik ◽  
Jacek Jakusz ◽  
Grzegorz Blakiewicz
Keyword(s):  
Dynamic Range ◽  
Low Voltage ◽  
Supply Voltage ◽  
Low Frequency ◽  
Cmos Technology ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Biomedical Sensors ◽  
Filter Synthesis ◽  
Cascade Method

Buffer-based CMOS filters are maximally simplified circuits containing as few transistors as possible. Their applications, among others, include nano to micro watt biomedical sensors that process physiological signals of frequencies from 0.01 Hz to about 3 kHz. The order of a buffer-based filter is not greater than two. Hence, to obtain higher-order filters, a cascade of second-order filters is constructed. In this paper, a more general method for buffer-based filter synthesis is developed and presented. The method uses RLC ladder prototypes to obtain filters of arbitrary orders. In addition, a set of novel circuit solutions with ultra-low voltage and power are proposed. The introduced circuits were synthesized and simulated using 180-nm CMOS technology of X-FAB. One of the designed circuits is a fourth-order, low-pass filter that features: 100-Hz passband, 0.4-V supply voltage, power consumption of less than 5 nW, and dynamic range above 60 dB. Moreover, the total capacitance of the proposed filter (31 pF) is 25% lower compared to the structure synthesized using a conventional cascade method (40 pF).

scholarly journals Photodetector resistant to background light noise with extended dynamic range of input signals

2021 ◽  
pp. 3-8
Author(s):  
V. M. Lipka ◽  
V. V. Ryukhtin ◽  
Yu. G. Dobrovolsky
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Modulation Frequency ◽  
Low Frequency ◽  
Gain Control ◽  
Ambient Air ◽  
Frequency Range ◽  
Background Light ◽  
Useful Signal ◽  
Extended Dynamic

Measurement of periodic optical information signals in the background light noise with a photodetector with extended dynamic range is an urgent task of modern electronics and thus has become the aim of this study. To increase the dynamic range of the photodetector, a new version of the automatic gain control (AGC) circuit has been developed, which consists of an AGC controller, an output photodetector amplifier and an AGC detector. The authors measured the dynamic range of the photodetector when receiving optical radiation with a wavelength of 1064 nm in the power range from 2.10–8 to 2.10–5 W at a modulation frequency of 20 kHz with the AGC on. Under these conditions, the dynamic range of the photodetector was found to be up to 67 dB. If the AGC was off, the dynamic range did not exceed 30 dB. Thus, the study made it possible to create a photodetector with an extended dynamic range up to 67 dB based on a new version of the AGC circuit. The design of the photodetector allowed choosing a useful signal of a particular modulation frequency in the frequency range from 3 to 45 kHz and effectively suppresses the frequencies caused by optical interference in the low frequency range from the frequency of the input signal of constant amplitude up to 3 kHz inclusive. This compensates the current up to 15 mA, which is equivalent to the power of light interference of about 15 mW. Further research should address the issues of reliability of the proposed photodetector design and optimization of its optical system. The photodetector can be used in geodesy and ambient air quality monitoring.

scholarly journals Inhibition in the balance: binaurally coupled inhibitory feedback in sound localization circuitry

2011 ◽  
Vol 106 (1) ◽  
pp. 4-14 ◽  
Author(s):  
R. Michael Burger ◽  
Iwao Fukui ◽  
Harunori Ohmori ◽  
Edwin W. Rubel
Keyword(s):  
Sound Localization ◽  
Arrival Time ◽  
Dynamic Range ◽  
Low Frequency ◽  
Neural Circuitry ◽  
Significant Progress ◽  
Interaural Time Differences ◽  
Inhibitory Function ◽  
Inhibitory Feedback ◽  
Auditory Systems

Interaural time differences (ITDs) are the primary cue animals, including humans, use to localize low-frequency sounds. In vertebrate auditory systems, dedicated ITD processing neural circuitry performs an exacting task, the discrimination of microsecond differences in stimulus arrival time at the two ears by coincidence-detecting neurons. These neurons modulate responses over their entire dynamic range to sounds differing in ITD by mere hundreds of microseconds. The well-understood function of this circuitry in birds has provided a fruitful system to investigate how inhibition contributes to neural computation at the synaptic, cellular, and systems level. Our recent studies in the chicken have made significant progress in bringing together many of these findings to provide a cohesive picture of inhibitory function.

A procedure for calibrating short-period telemetered seismograph systems

1988 ◽  
Vol 78 (6) ◽  
pp. 2077-2088
Author(s):  
M. C. Chapman ◽  
J. A. Snoke ◽  
G. A. Bollinger
Keyword(s):  
Dynamic Range ◽  
Low Frequency ◽  
Inertial Mass ◽  
System Response ◽  
Total System ◽  
Electronic Components ◽  
Amplitude Response ◽  
Motion System ◽  
Short Period ◽  
The Hilbert Transform

Abstract Efficient low-frequency calibration of the entire seismograph system can be accomplished by Fourier analysis of the system response to automatically generated transient test functions applied to the seismometer calibration coil. Typically, such calibrations are restricted to frequencies less than 10 Hz by the ambient ground motion, system noise, and limited dynamic range. To extend the calibration to a broader frequency range, we disconnect the seismometer and take advantage of the fact that the relative amplitude response of the electronic components in most systems can be measured with high accuracy at frequencies from as low as 0.02 Hz to the Nyquist frequency (e.g., 50 Hz) using standard electronics test equipment. The low-frequency amplitude response of the seismometer can then be isolated by dividing the total system response by that obtained for the electronic components. An iterative least-squares procedure is used to estimate the natural frequency and damping coefficient of the seismometer, along with a scaling parameter that specifies the absolute gain of the system. The phase response of the system is calculated directly from the amplitude response using the Hilbert transform. The procedure assumes that the seismometer is an ideal damped harmonic oscillator and that the system as a whole acts as a minimum phase filter. The only instrumental constants that must be known from independent measurement are the seismometer calibration coil force constant and the inertial mass.

COMPARATIVE ANALYSIS OF NEUROPHYSIOLOGICAL FEATURES IN YOUNG WOMEN AND MEN SUFFERING FROM EPILEPSY

2021 ◽  
pp. 63-66
Author(s):  
A. О. Voitiuk ◽  
T. А. Litovchenko
Keyword(s):  
Comparative Analysis ◽  
Slow Wave ◽  
Low Frequency ◽  
Neurological Status ◽  
High Amplitude ◽  
Bioelectrical Activity ◽  
Key Words Epilepsy ◽  
Θ Rhythm ◽  
Definition Of ◽  
Gender Specific

The definition of epilepsy via the concept of neuronal discharge indicates the crucial importance of electroencephalography (EEG) in epileptology. This pathology is a certain problem for each sex, that requires gender−specific approaches when managing and treating such patients. To investigate them, 30 men and 30 women aged 18−44 years with a reliable diagnosis of epilepsy were examined. A comprehensive clinical, neurological and neurophysiological study of patients was performed, taking into account the data of clinical case and life history. Each patient was assessed for neurological status according to traditional methods, electrophysiological method of examination (routine EEG) was used. On the results of electroencephalography in individuals of both sexes with epilepsy, there was a decrease in the amplitude of the α−rhythm, but a significant slowdown in this rhythm was not detected. Most patients had high−amplitude (> 20 μV) and low−frequency β1−rhythm. Low−frequency high−amplitude slow−wave activity was regarded as an EEG reflection of degenerative−dystrophic processes in brain. Photostimulation caused paroxysms of bilaterally synchronous sharp and slow waves, complexes of "acute−slow" wave. Hyperventilation led to an increase in the θ−rhythm amplitude, appearance of δ−waves, higher expression of true epileptiform phenomena: adhesions, "acute wave−slow wave" complexes, "spike−slow wave" complexes. A comparative analysis of the obtained results allowed to conclude that the changes in bioelectrical activity in epilepsy occur according to the general mechanisms of epileptogenesis, regardless of gender. Key words: epilepsy, electroencephalogram, comparative analysis, young men and women.

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