scholarly journals Portable and Highly Versatile Impedance Meter for Very Low Frequency Measurements

2021 ◽  
Vol 11 (17) ◽  
pp. 8234 ◽  
Author(s):  
Graziella Scandurra ◽  
Antonella Arena ◽  
Emanuele Cardillo ◽  
Gino Giusi ◽  
Carmine Ciofi
Keyword(s):  
Low Cost ◽  
Low Frequency ◽  
Impedance Measurement ◽  
Digital Signal ◽  
Low Complexity ◽  
Electrical Impedance Spectroscopy ◽  
Low Frequencies ◽  
Core System ◽  
Very Low Frequency ◽  
Public Domain Software

Electrical Impedance Spectroscopy (EIS) is a characterization technique that is gaining more and more importance in various fields of research and applications. The frequency range of investigation varies according to the type of application. In some fields (biology, medicine, energy) it is useful to be able to perform measurements at very low frequency values (down to a few mHz or even below). While impedance meters operating at frequencies in the range from a few tens of Hz up to a few MHz can be regarded as quite standard pieces of instrumentation commonly available in many laboratories, instrumentation for measurements at very low frequencies, although commercially available, is less common. The subject of this work is the design, realization and testing of a low frequency impedance measurement platform that has the advantage of being portable, rather inexpensive, and yet highly versatile. In our approach, we exploit a personal computer and a soundboard as a powerful system for digital signal generation and analysis that, with the help of low complexity and low-cost external hardware and a public domain software for the implementation of the core system, allow to tailor the platform for targeting specific applications with minimal effort. As an example, we will demonstrate the application of the system to the investigation of polypyrrole-based supercapacitor structures.

scholarly journals Review on the Millimeter-Wave Generation Techniques Based on Photon Assisted for the RoF Network System

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jiangnan Xiao ◽  
Chuang Zhao ◽  
Xingxing Feng ◽  
Xu Dong ◽  
Jiangli Zuo ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Cost ◽  
Electronic Devices ◽  
Low Frequency ◽  
Digital Signal ◽  
Development Trend ◽  
Wave Generation ◽  
Communication Link ◽  
Network System ◽  
High Frequency Microwave

With the development trend of wireless and broadband in the communication link and even the whole information industry, the demand of high-frequency microwave bandwidth has been increasing. The RoF network system solves the problem of spectrum congestion in low-frequency band by providing an effective technology for the distribution of high-frequency microwave signals over optical fiber links. However, the traditional mm-wave generation technique is limited by the bandwidth of electronic devices. It is difficult to generate high-frequency and low-phase noise mm-wave signals with pure electrical components. The mm-wave communication technology based on photon assisted can overcome the bandwidth bottleneck of electronic devices and provide the potential for developing the low-cost infrastructure demand of broadband mobile services. This paper will briefly explain the characteristics of the RoF network system and the advantages of high-frequency mm-wave. Then we, respectively, introduce the modulation schemes of RoF mm-wave generation based on photon assisted including directly modulated laser (DML), external modulation, and optical heterodyne. The review mainly focuses on a variety of different mm-wave generation technologies including multifrequency vector mm-wave. Furthermore, we list several approaches to realize the large capacity data transmission techniques and describe the digital signal processing (DSP) algorithm flow in the receiver. In the end, we summarize the RoF network system and look forward to the future.

scholarly journals Digital signal processsing functions for ultra-low frequency calibrations

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 374
Author(s):  
Henrik Ingerslev ◽  
Soren Andresen ◽  
Jacob Holm Winther
Keyword(s):  
Signal Processing ◽  
Low Frequency ◽  
Digital Signal ◽  
Low Noise ◽  
Key Comparison ◽  
Low Frequencies ◽  
Dual Channel ◽  
Ultra Low Noise ◽  
Lower Noise ◽  
Better Than

The demand from industry to produce accurate acceleration measurements down to ever lower frequencies and with ever lower noise is increasing. Different vibration transducers are used today for many different purposes within this area, like detection and warning for earthquakes, detection of nuclear testing, and monitoring of the environment. Accelerometers for such purposes must be calibrated in order to yield trustworthy results and provide traceability to the SI-system accordingly. For these calibrations to be feasible, suitable ultra low-noise accelerometers and/or signal processing functions are needed. <br />Here we present two digital signal processing (DSP) functions designed to measure ultra low-noise acceleration in calibration systems. The DSP functions use dual channel signal analysis on signals from two accelerometers measuring the same stimuli and use the coherence between the two signals to reduce noise. Simulations show that the two DSP functions are estimating calibration signals better than the standard analysis. <br />The results presented here are intended to be used in key comparison studies of accelerometer calibration systems, and may help extend current general low frequency range from e.g. 100 mHz down to ultra-low frequencies of around 10mHz, possibly using somewhat same instrumentation.

Infrasonic Music

2009 ◽  
Vol 19 ◽  
pp. 51-56 ◽  
Author(s):  
Cat Hope
Keyword(s):  
Low Frequency ◽  
Low Frequencies ◽  
Very Low Frequency ◽  
Frequency Sound ◽  
The Way

Low-frequency sound on the cusp of the audible offers the possibility of redefining the way we think about listening to music. As the perception of pitch is lost in very low-frequency sound emissions, an opportunity arises for a different kind of music and a different way of listening. Low frequencies can be engaged to activate responses other than the aural or be used as a kind of “silent activator,” enabling or affecting other sounds. This article explores the possibilities for what may be called an “infrasonic music.”

scholarly journals Performance Evaluation of Low Cost Analog Feedback Active Noise Cancellation System

2019 ◽  
Vol 8 (3S) ◽  
pp. 142-145
Keyword(s):  
Digital Signal Processor ◽  
Acoustic Noise ◽  
Low Cost ◽  
Low Frequency ◽  
Digital Signal ◽  
Noise Cancellation ◽  
Frequency Noise ◽  
Active Noise Cancellation ◽  
Active Noise ◽  
The Cost

Acoustic noise can be reduced by active noise cancellation (ANC) and passive noise cancellation (PNC) algorithm. The PNC can effectively attenuate the noise with high frequency, but not the noise with low frequency. ANC is one of the promising solution to reduce the low frequency noise. Commercial ANC headphones often use the digital signal processor (DSP) to perform the noise cancellation algorithm to cancel the annoying acoustic noise, but the cost is relatively high. A low-cost ANC solution is urgently needed to reduce the acoustic noise. The relationship between the frequency, distance and degree of magnitude of the noise level are also evaluated in this paper.

scholarly journals Very low-frequency IEPE accelerometer calibration and application to a wind energy structure

2021 ◽  
Author(s):  
Clemens Jonscher ◽  
Benedikt Hofmeister ◽  
Tanja Grießmann ◽  
Raimund Rolfes
Keyword(s):  
Measurement Data ◽  
Low Frequency ◽  
Calibration Procedure ◽  
Low Noise ◽  
Energy Structure ◽  
Frequency Range ◽  
Low Frequencies ◽  
Iir Filters ◽  
Very Low Frequency ◽  
Ac Response

Abstract. In this work, we present an experimental setup for very low-frequency calibration measurements of low-noise Integrated Electronics Piezo Electric (IEPE) accelerometers and a customised signal conditioner design for using IEPE sensor down to 0.05Hz. AC-response IEPE accelerometer and signal conditioners have amplitude and phase deviations at low frequencies. As the standard calibration procedure in the low-frequency range is technically challenging, IEPE accelerometers with standard signal conditioners are usually used in frequency ranges above 1 Hz. Vibrations on structures with low eigenfrequencies like wind turbines are thus often monitored using DC-coupled micro-electro-mechanical systems (MEMS) capacitive accelerometers. This sensor type suffers from higher noise levels compared to IEPE sensors. To apply IEPE sensors instead of MEMS sensors, in this work the calibration of the entire measurement chain of three different IEPE sensors with the customised signal conditioner is performed with a low-frequency centrifuge. The IEPE sensors are modelled using IIR filters to apply the calibration to time-domain measurement data of a wind turbine support structure. This procedure enables an amplitude and phase-accurate vibration analysis with IEPE sensors in the low-frequency range down to 0.05 Hz.

scholarly journals High Frequency Performance of Piezoelectric Diaphragms for Impedance-Based SHM Applications

2020 ◽  
Vol 2 (1) ◽  
pp. 16
Author(s):  
Guilherme Rezende ◽  
Fabricio Baptista
Keyword(s):  
High Frequency ◽  
Structural Damage ◽  
Low Cost ◽  
Low Frequency ◽  
Experimental Tests ◽  
Piezoelectric Transducers ◽  
Low Frequencies ◽  
High Frequencies ◽  
Electromechanical Impedance ◽  
Damage Indices

Piezoelectric transducers are used in a wide variety of applications, including damage detection in structural health monitoring (SHM) applications. Among the various methods for detecting structural damage, the electromechanical impedance (EMI) method is one of the most investigated in recent years. In this method, the transducer is typically excited with low frequency signals up to 500 kHz. However, recent studies have indicated the use of higher frequencies, usually above 1 MHz, for the detection of some types of damage and the monitoring of some structures’ characteristics that are not possible at low frequencies. Therefore, this study investigates the performance of low-cost piezoelectric diaphragms excited with high frequency signals for SHM applications based on the EMI method. Piezoelectric diaphragms have recently been reported in the literature as alternative transducers for the EMI method and, therefore, investigating the performance of these transducers at high frequencies is a relevant subject. Experimental tests were carried out with piezoelectric diaphragms attached to two aluminum bars, obtaining the impedance signatures from diaphragms excited with low and high frequency signals. The analysis was performed using the real part of the impedance signatures and two basic damage indices, one based on the Euclidean norm and the other on the correlation coefficient. The experimental results indicate that piezoelectric diaphragms are usable for the detection of structural damage at high frequencies, although the sensitivity decreases.

Dielectric Properties in Fresh Trabecular Bone Tissue from 1MHz to 1000MHz: A Fast and Non Destructive Quality Evaluation Technique

2010 ◽  
Vol 638-642 ◽  
pp. 730-735 ◽  
Author(s):  
Ramiro M. Irastorza ◽  
Sergio Valente ◽  
Fernando Vericat ◽  
Eugenia Blangino
Keyword(s):  
Dielectric Properties ◽  
Frequency Domain ◽  
Quality Evaluation ◽  
Low Cost ◽  
Low Frequency ◽  
Electrical Impedance Spectroscopy ◽  
Sample Population ◽  
Strongly Correlated ◽  
Trabecular Bones ◽  
Non Destructive

The increasing research on development of novel bio-materials has resulted in several studies on non-destructive evaluation methods for characterizing these materials and the biological materials receiving them. A broad range of techniques are available. As an alternative tool, electrical impedance spectroscopy, has become a widely used, non destructive and low cost technique in material quality evaluation. Particularly in bones, it has also been demonstrated that mechanical characteristics are strongly correlated to dielectric properties. In this work, non destructive estimation (the same samples can be tested using other techniques) of the dielectric properties of fresh trabecular bones (layered lossy structure) using coaxial probes is analyzed from 1MHz to 10MHz (in frequency domain) and from 80MHz to 1GHz (in both, frequency and time domain). Frequency domain system identification is used to build the estimation in the low frequency range and an orthonormal based identification approach, for the high frequency data. Comments on conductive samples, non Debye dielectrics and polarization effects are added. The methodology was applied to a particular human sample population of aged adult femur heads and results are presented here. A comparison with destructive test, in which the samples were machined into cylinders of 7mm diameter, is also performed.

scholarly journals Low Frequency Radio Astronomy from Earth Orbit

1990 ◽  
Vol 123 ◽  
pp. 508-508
Author(s):  
Kurt W. Weiler ◽  
Namir E. Kassim
Keyword(s):  
Wavelength Range ◽  
Radio Astronomy ◽  
Low Cost ◽  
Low Frequency ◽  
Earth Orbit ◽  
The Moon ◽  
Low Frequencies ◽  
Frequency Space ◽  
Current Technology

AbstractLow frequency radio astronomy for the purpose of this discussion is defined as frequencies ≲100 MHz. Since the technology is fairly simple at these frequencies and even Jansky’s original observations were made at 20.5 MHz, there have been many years of research at these wavelengths. However, though radio astronomers have been working at low frequencies since the first days of science, the observing limitations and the move of much of the effort to ever shorter wavelengths has meant that most areas still remain to be fully exploited with modern techniques and instruments. In particular, the possibilities for pursuing the very lowest frequencies by interferometry of ground to space, in Earth orbit, or from the Moon promises a rebirth of work in this wavelength range.We present concepts for space-ground VLBI and a fully space-based array in high Earth orbit to pursue the astrophysics which can only be probed at these frequencies. An Orbiting Low Frequency Radio Astronomy Satellite (OLFRAS) and a Low Frequency Space Array (LFSA) are two concepts which will open this last, poorly explored area of astronomy at relatively low cost and well within the limits of current technology.

Electrode and electrodeless impedance measurement for determination of orange juices parameters

2015 ◽  
Vol 69 (7) ◽  
Author(s):  
Romana Seidlová ◽  
Jaroslav Poživil ◽  
Jaromír Seidl ◽  
Stanislav Ďaďo ◽  
Petra Průšová ◽  
...  
Keyword(s):  
Equivalent Circuit ◽  
Low Cost ◽  
Impedance Measurement ◽  
Electrical Impedance Spectroscopy ◽  
Impedance Method ◽  
High Tech ◽  
Element Approximation ◽  
Ant Colonies ◽  
Real Time Measurement ◽  
Circuit Components

AbstractElectrical impedance spectroscopy (EIS) is a non-destructive, rapid and real-time measurement method which does not require special high-tech measurement devices and can be applied to food quality assessment. This method is rapid, effective and affords low-cost investigation of the product. The conventional EIS method requires a set of metal electrodes in direct contact with the medium to be measured. The complicated electrochemical processes on the electrodes-electrolyte interface could substantially affect the value of the impedance measured. The present study sought to explore the possibilities of using the impedance method for quality control in orange juices, to introduce the electrodeless method of electrolyte impedance measurement and to compare this with the conventional impedance methods. The electrical properties of the orange juices were described with the help of an equivalent circuit. An equivalent circuit was designed with constant phase element approximation. The values of the equivalent circuit components were fitted using a non-standard algorithm inspired by the behaviour of actual ant colonies. Implementing the electrodeless method obviated the electrodes phenomena effects and the behaviour of the electrolyte is similar to inductance. The proposed electrodeless method is generally applicable to measuring the electrochemical properties of electrolytes.

Coupling of sympathetic nerve traffic and BP at very low frequencies is mediated by large-amplitude events

2003 ◽  
Vol 284 (3) ◽  
pp. R802-R810 ◽  
Author(s):  
Don E. Burgess ◽  
David C. Randall ◽  
Richard O. Speakman ◽  
David R. Brown
Keyword(s):  
Sympathetic Nerve ◽  
Wavelet Transforms ◽  
Large Amplitude ◽  
Low Frequency ◽  
Functional Connection ◽  
Low Frequencies ◽  
Very Low Frequency ◽  
Arterial Blood ◽  
Wide Range ◽  
Transient Events

This study explores the functional association between renal sympathetic nerve traffic (NT) and arterial blood pressure (BP) in the very-low-frequency range (i.e., <0.1 Hz). NT and BP ( n = 6) or BP alone ( n = 17) was recorded in unanesthetized rats ( n = 6). Data were collected for 2–5 h, and wavelet transforms were calculated from data epochs of up to 1 h. From these transforms, we obtained probability distributions for fluctuation amplitudes over a range of time scales. We also computed the cross-wavelet power spectrum between NT and BP to detect the occurrence in time of large-amplitude transient events that may be important in the autonomic regulation of BP. Finally, we computed a time sequence of cross correlations between NT and BP to follow the relationship between NT and BP in time. We found that NT and BP follow comparable self-similar scaling relationships (i.e., NT and BP fluctuations exhibit a certain type of power law behavior). Scaling of this nature 1) points to underlying dynamics over a wide range of scales and 2) is related to large-amplitude events that contribute to the very-low-frequency variability of NT and BP. There is a strong correlation between NT and BP during many of these transient events. These strong correlations and the uniformity in scaling imply a functional connection between these two signals at frequencies where we previously found no connection using spectral coherence.

Sign in / Sign up

Export Citation Format

Share Document