Journal articles on the topic 'Electromagnetic interference. Mixed signal circuits'

The work is devoted to the problem of frequency-selective signal conversion in microelectronic sensor devices. It has been shown that the signal path of such devices, in particular, sensor nodes in the concept of the Internet of Things, must meet the requirements of embedded systems using a mixed analog-digital front end. The analysis of the signal transformation of photovoltaic sensors, in particular the problem of a significant parasitic influence of extraneous non-informative optical radiation and electromagnetic interference, has been carried out. SPICE models of photovoltaic sensor signal circuits providing frequency selection on bandwidth filters have been synthesized. The main approaches of hardware-software implementation of the built-in system of frequency selection with the mixed-signal transformation are considered. The signal path of the embedded system includes a gyrator, a software-controlled amplifier, a synchronous demodulator, an analog-to-digital converter, and a digital filter. The implementation is carried out on the platform of the programmable system on a PSoC chip. The integrated circuits of the PSoC 5 LP Family Cypress Semiconductor Corporation are used with a wide range of programmable analog front-end nodes, in particular operating amplifiers, comparators, units on switching capacitors, reference voltage sources on the principle of the forbidden zone, analog multiplexers, signal synthesizers, etc. The efficiency of the mixed analog and digital signal conversion is shown.

At present, main AC power systems of advanced fighters all apply digital controllers with microprocessors. The signal input and output circuits are vulnerable to the effects of electromagnetic interference, which may cause air-power-off fault. The paper analyzes the electromagnetic environment on the aircraft, discusses the airborne electromagnetic compatibility by comparing domestic and international contents and limitations of the electromagnetic standard. Furthermore, it proposes measures to resolve the electromagnetic compatibility

It is inevitable that high-intensity, wide-spectrum electromagnetic emissions are generated by the power electronic equipment of the Extra High Voltage (EHV) power converter station. The surveillance flight of Unmanned Aerial Vehicles (UAVs) is thus, situated in a complex electromagnetic environment. The ubiquitous electromagnetic interference demands higher electromagnetic protection requirements from the UAV construction and operation. This article is related to the UAVs patrol inspections of the power line in the vicinity of the EHV converter station. The article analyzes the electromagnetic interference characteristics of the converter station equipment in the surrounding space and the impact of the electromagnetic emission on the communication circuits of the UAV. The anti-electromagnetic interference countermeasures strive to eliminate or reduce the threats of electromagnetic emissions on the UAV’s hardware and its communication network.

The most important operation of electrocardiogram (ECG) signal measurement device is to amplify signal and maintain correct original signal. The operation of all circuits cause electromagnetic interference (EMI), but EMI can be reduced by using special component or some PCB layout approaches. This paper provides an example of portable ECG device to demonstrate a method that can effectively reduce EMI and be applied in finished product. This research has built a lead-1 ECG to reach a low noise operation. This result can be easily applied to portable ECG measurement.

In connection with electromagnetic interference influence on the track circuits, the purpose of the research is finding the means to increase the noise immunity of an audio frequency track circuit. The authors propose a new engineering solution, which enables reducing the effect of noises on the input of the track receiver in the intervals between signal current pulses. The proposed noise-immune audio frequency track circuit is based on inserting a delay line, an adjustable single-pulse generator and a controlled electronic switch into the existing audio frequency track circuit equipment. To analyze its efficiency, the operation of the audio frequency track circuit was simulated under conditions of traction current disturbances, impulse and fluctuation interferences with the known parameters. The results show that proposed device for railway transport allows to increase a signal-to-noise ratio on the track receiver input from 8% to 30%, depending on the interference parameters and the level of the useful signal.

An ultra-low power, portable, and easily implemented Holter recorder is necessary for patients or researchers of electrocardiogram (ECG). Such a Holter recorder with off-the-shelf components is realized with mixed signal processor (MSP) in this paper. To decrease the complexity of analog circuits and the interference of 60 Hz noise from power line, we use the MSP to implement a finite impulse response (FIR) filter which is equiripple design. We also integrate the ring buffer for the input samples and the symmetrical characteristic of the FIR filter for efficiently computing convolution. The experimental results show that the ECG output signal with the PQRST feature is easy to be distinguished. This ECG signal is recorded for 24 hours using a SD card. Furthermore, the ECG signal is transmitted with a smartphone via Bluetooth to decrease the burden of the Holter recorder. As a result, this paper uses the Lomb method for the spectral analysis of Heart Rate Variability (HRV) better than Fast Fourier Transform (FFT).

Abstract. In this contribution, a system identification procedure of a two-input Wiener model suitable for the analysis of the disturbance behavior of integrated nonlinear circuits is presented. The identified block model is comprised of two linear dynamic and one static nonlinear block, which are determined using an parameterized approach. In order to characterize the linear blocks, an correlation analysis using a white noise input in combination with a model reduction scheme is adopted. After having characterized the linear blocks, from the output spectrum under single tone excitation at each input a linear set of equations will be set up, whose solution gives the coefficients of the nonlinear block. By this data based black box approach, the distortion behavior of a nonlinear circuit under the influence of an interfering signal at an arbitrary input port can be determined. Such an interfering signal can be, for example, an electromagnetic interference signal which conductively couples into the port of consideration.

A method of shielding the elements of a microwave module based on the principles of forming a Faraday cage, with different power and different frequency paths of the AFAR receiving-transmitting module, excluding their mutual electromagnetic influence, is presented. A description of the structure of a multilayer board and various structural elements is given, allowing to limit (screen) the signal in a small volume, commensurate with the size of a monolithic integrated circuit or a set of monolithic integrated circuits, isolating parasitic electromagnetic interference. Polyimide is considered as a dielectric material of a multilayer microwave board for use in space technology devices, as well as promising design solutions for reducing the mass and dimensions of the module.

Research studies have shown that digital wireless phones interact with some hearing aids, creating a buzzing noise that may reduce speech intelligibility. Interference signals for three phone technologies were generated at five sound pressure levels (35 dB, 45 dB, 55 dB, 65 dB, and 75 dB) and mixed with speech at 65 dB SPL to test the speech intelligibility of 24 hearing-impaired people. A “No Noise” condition was also tested. Scores for the TDMA-217 Hz phone signal at low speech-to-noise ratios (<10 dB) were significantly lower than those for CDMA and TDMA-50 Hz at the same level. The CDMA and TDMA-50 Hz phone signals had a similar effect on speech intelligibility. Speech intelligibility scores at speech-to-noise ratios of 20 dB and 30 dB were similar to those for the “No Noise” condition. The articulation index represented the best index for predicting the impact of wireless phone interference on speech intelligibility.

The study was carried out (2020) to reduce the effect of electromagnetic interference generated by a device for the formation of temperature effects based on Peltier element on a plant biopotential meter. Four variants of equipment grounding circuits are considered in the absence of a separate grounding bus for power equipment; graphs of biopotential signals are given. The type of interference that the device for the formation of temperature effects induces on the biopotential measurement channel is shown. The control unit case for the temperature-controlled stage based on Peltier element and the power cable shield for connecting Peltier element to the control unit must be grounded at a separate point from the biopotential meter. Biopotential meter electrodes should be grounded as far as possible from the control unit case and at a separate point from the grounding of the plate of the temperature-controlled stage. Recommendations are given for the grounding of high impedance input measuring devices and the power equipment emitting powerful inductive interference and causing interference in the grounding bus located in the same laboratory room, in the absence of separate grounding for power equipment. To reduce interference to an acceptable level, in addition to the selection of the grounding point, filtering is required. If the grounding point is selected incorrectly, a signal with a high level of interference is present at the filter output. The application of the proposed recommendations for grounding a device for the formation of a temperature effect based on Peltier element and a biopotential meter makes it possible to assess the response of a plant placed on the temperature-controlled stage to a temperature effect and not complicate programmed filtering of the signal received by the biopotential meter.

As the trend of consumer electronics and mobile communications devices is obviously developing toward to miniature and high-speed processing, the problem involving with electromagnetic compatibility (EMC) or radio frequency interference (RFI) is becoming more critical for the system integration of high-speed digital and RF mixed signal platforms. This paper is mainly focusing on the characteristics analysis of various electromagnetic shielding materials by utilizing the various shielding effectiveness (SE) measuring methods developed by TDK and ASTM (ASTM D4935). We also adopt the electromagnetic interference (EMI) testing methods developed by IEC for chip level (IEC 61967-3 and IEC 61967-6) to investigate the characteristics and distribution of EMI noise sources. To effectively shield the electric, magnetic, or electromagnetic field originated from noise source, we thus analyze the shielding capability for various materials with different measuring methods. Finally, we will show the EMI reduction and RF performance improvement with implementation of shielding material on module under investigated. With the systematic measurement and analysis described in this paper, we can further identify the related EMI problem and resolve the severe chip or module level EMC problem more effectively.

Multiresolution analog-to-digital converters (MRADC) are usually used in Time Domain ElectroMagnetic Interference (TDEMI) measuring systems for very fast signal sampling with a sufficient dynamic range. The properties of the spectrum measured by the TDEMI system influenced by imperfections in the MRADC are analyzed in this paper. Errors are caused by imperfect matching of the offset and gain and phase of the circuits used in parallel input channels typical for the MRADC. For deep analyses of MRADC behavior, a precise mathematical model has been created using the concept of additive error pulses. Furthermore, a dedicated process of the identification of discrepancy parameters from experimental data is proposed. Identified parameters enter the expressions of the model and enable side to side comparison of experimental and theoretical results.

Properties of Silicon Carbide Junction Field Effect Transistor (SiC JFET) such as high switching speed, low forward voltage drop and high temperature operation have attracted the interest of power electronic researchers and technologists, who for many years developed devices based on Silicon (Si). A number of power system Engineers have made efforts to develop more robust equipment including circuits or modules with higher power density. However, it was realized that several available power semiconductor devices were approaching theoretical limits offered by Si material with respect to capability to block high voltage, provide low on-state voltage drop and switch at high frequencies. This paper presents an overview of the current applications of SiC JFET in circuits such as inverters, rectifiers and amplifiers. Other areas of application reviewed include; usage of the SiC JFET in pulse signal circuits and boost converters. Efforts directed toward mitigating the observed increase in electromagnetic interference were also discussed. It also presented some areas for further research, such as having more applications of SiC JFET in harsh, high temperature environment. More work is needed with regards to SiC JFET drivers so as to ensure stable and reliable operation, and reduction in the prices of SiC JFETs through mass production by industries.

A method for separating multisource partial discharges (PDs) in a substation is proposed based on selected bispectra of ultrahigh frequency (UHF) electromagnetic waves. Bispectra are sensitive to Gaussian noises and processes of symmetrical distribution. The phase information contained in bispectra can be useful and important for further signal processing. Bifrequencies where Fisher-like class separability measures between signals’ bispectra achieve their maximums are selected as characteristic parameters of the signals. Then, the selected bispectra are utilized for training the radial basis neural network to separate PD UHF signals in a substation. The method is used to analyze simulated UHF signals mixed with Gaussian white noise and frequency-fixed interference, and to separate PD UHF signals that are collected in a 500 kV substation. In order to prove the validity of the proposed separation method, the localization results are compared with the results calculated by time delay sequence, and the proposed separating algorithm is verified in the interference circumstances of a substation. However, the exact location of PD sources cannot be calculated according to the time delay sequence when the PD sources in a substation are close to each other or there are fewer than four antennas for receiving signals.

Power line communication (PLC) is increasingly emerging as an important communication technology for the smart-grid environment. As PLC systems use the existing infrastructure, they are always exposed to conducted electromagnetic interference (EMI) from switching mode power converters, which need to be tightly controlled to meet EMC regulations and to ensure the proper operation of the PLC system. For this purpose, spread-spectrum modulation (SSM) techniques are widely adopted to decrease the amplitude of the generated EMI from the power converters so as to comply with EMC regulations. In this paper, the influence of a spread-spectrum-modulated SiC-based buck converter on the G3-PLC channel performance is described in terms of channel capacity reduction using the Shannon–Hartley equation. The experimental setup was implemented to emulate a specific coupling path between the power and communication circuits and the channel capacity reduction was evaluated by the Shannon–Hartley equation in several operating scenarios and compared with the measured frame error rate. Based on the obtained results, SSM provides the EMI spectral peak amplitude reduction required to pass the electromagnetic compatibility (EMC) tests, but results in increased EMI-induced channel capacity degradation and increased transmission error rate in PLC systems.

Multiresolution analog-to-digital converters (MRADC) are usually used in Time Domain ElectroMagnetic Interference (TDEMI) measuring systems for very fast signal sampling with a sufficient dynamic range. The properties of the spectrum measured by the TDEMI system influenced by imperfections in the MRADC are analyzed in this paper. Errors are caused by imperfect matching of the offset and gain and phase of the circuits used in parallel input channels typical for the MRADC. For deep analyses of MRADC behavior, a precise mathematical model has been created using the concept of additive error pulses. Furthermore, a dedicated process of the identification of discrepancy parameters from experimental data is proposed. Identified parameters enter the expressions of the model and enable side to side comparison of experimental and theoretical results.Novel, multi-path, time-interleaved digital sigma-delta modulators that can operate at any arbitrary frequency from DC to Nyquist are designed, analysed and synthesized in this study. Dual- and quadruple-path fourth-order Butterworth, Chebyshev, Inverse Chebyshev and Elliptical based digital sigma-delta modulators, which offer designers the flexibility of specifying the centre-frequency, pass-band/stop-band attenuation as well as the signal bandwidth are presented. These topologies are compared in terms of their signal-to-noise ratios, hardware complexity, stability, tonality and sensitivity to non-idealities. Detailed simulations performed at the behavioural-level in MATLAB are compared with the experimental results of the FPGA implementation of the designed modulators. The signal-to-noise ratios between the simulated and empirical results are shown to be different by not more than 3-5 dBs. Furthermore, this paper presents the mathematical modelling and evaluation of the tones caused by the finite wordlengths of these digital multi-path sigma-delta modulators when excited by sinusoidal input signals.

This paper presents the experimental implementation of a buck converter with quasi-sliding mode control combined with a loss estimator function. An online loss estimator is developed to estimate, in real time, the parasitic resistances of the converter and variations of the resistance in the load. The estimated loss resistance and the resistance of the load are embedded, in real time, into the model equations of the controller using Zero Average Dynamics and Fixed Point Induction Control techniques (ZAD-FPIC) to improve the control robustness to resistive parameter variations. Details of the experimental setup are presented to show developed electrical and electronic circuits, and experimental techniques are described to ensure the successful digital implementation of closed-loop control of the buck power converter. The proper shielding of electrical wiring in power electronics allows improvement to the quality of the measures by removing noise induced by electromagnetic interference. A trigger signal is used to implement the Pulse-Width Modulation (PWM) with centered pulse and to synchronize the sampling of analogical signals from the buck converter. Such synchronization allows the use of a lower sampling frequency and ensures the measurements at the right instant in time. Experimental results are in good agreement with numerical simulations, showing the effectiveness of the control approach.

Analysis of structural construction of existing three-dimensional accelerometers is carried out, in which due to the opposite direction of sensitivity vectors and direction of measured inertial force, they allow to measure only linear inertia and accelerations varying in relatively small limits. On the other hand, due to the presence of elements in them that create electromagnetic fields, their construction is somewhat complicated. In addition, in known accel-erometers, due to the absence of a measurement object position sensor and an electronic control circuit, the func-tionality of the accelerometer is limited, Due to lack of integrator for acceleration integration, speed measurement is not provided, Due to rigid attachment of piezoelectric sensing elements through their bases, during measurement they generate interference signals, The amplitude of which exceeds the amplitude of the useful signal, which does not ensure reliability of the measured acceleration or speed and due to the presence of sensitive piezoelectric ele-ments, Having higher rigidity and requiring relatively large mechanical forces for generation of signals during mo-tion of acceleration and speed measurement object in automatic mode, which reduces sensitivity of accelerometer. Invention proposes new design and control scheme of three-dimensional piezoelectric accelerometer for measure-ment of dynamic parameters of moving objects in automatic mode. Wherein providing the position sensor of the moving measurement object with a three-axis signal detection unit to determine a direction of motion with meas-urement of acceleration or linear velocity when the measurement object moves along the coordinate axis; With the help of differential operational amplifiers through pulse generators and integrators, Speed measurement is provided by damping piezoelectric elements when the measurement object moves along one of the coordinate axes; Across the other two axes, the generated interference signals by amplitude are significantly reduced by their redemption; Having a piezoelectric element in the structure in the form of two-layer flat plates with an excitation section and a sensor section; Which generates signals at fast-changing acceleration and speed of moving object, amplitude of signal and sensitivity increases in 4-5 due to generation of signal by sensitive elements in vibration excitation mode created in accelerometer. Mathematical basis for accelerometer control circuits, mathematical model of its functioning is developed, applica-tion of which increases sensitivity of measurement of linear accelerations and speeds of moving objects and expands functional capabilities.

Abstract With the number of connected-devices increasing tremendously, communication data rates are projected to be at least 10–100X in the 5G/mm-wave (MMW) technology - much higher than the existing 4G LTE connections.[1], [2] To catch up with the trend, novel packaging technology in the MMW frequency range is required, which will address fundamental MMW technical challenges such as high dielectric loss, degradation of quality factors in passives, increased parasitic, dramatically-enhanced electromagnetic interference, and the reduced radiation efficiency of antenna arrays. State-of-the-art approaches being pursued include organic-core substrates that have a low dielectric constant (Dk) and low dissipation factor (Df) such as fluorine based or liquid-crystal polymer (LCP) substrates in order to achieve enhanced antenna performance and low signal dissipations. These organic-based substrate technologies, however, can neither miniaturize packages nor handle precision signal routings that enable high density packages. To address these challenges, attention is focused on Fan-Out Wafer Level Package (FOWLP) technologies, like eWLB, InFO, and SWIFT, where integrated circuits (ICs) are embedded in epoxy molding compound. [3]–[6] Recently, glass-panel embedding (GPE) technology is emerging as an ideal packaging methodology that enables superior performance along with small form factor, ultra-low-loss, high density, ultra-short interconnects, and low cost. [7] These benefits stem from the advantages of using glass which has excellent properties such as ultra-smooth surface for precision redistribution layer (RDL), exceptional dimensional stability for panel-scalability and tailorability of CTE that allow direct board-attach for improved system performance. In addition, utilizing the epoxy molding compounds as encapsulation material allows the GPE package to be thinner and more robust package with small farm factor. Molding of glass cavity panels also helps with the handling of ultra-thin glass which is seen as a bottleneck towards glass based packaging solutions in production. These facilitates enhanced throughput by allowing more cavity cut outs (more coupons) per panel. This paper presents the first demonstration of ultra-thin GPE with sheet type epoxy molding compound (SMC) for 5G/mm-wave applications. First part of this paper discusses the process-flow used in glass-panel embedding with laminated SMC, including chip placement in glass cavities, lamination of SMC, and the reliability of the package architecture. This paper reports on such a demonstration in 60 μm glass substrates with 40 μm thickness SMC. The second part of this paper focuses on low-loss interconnects for 5G/mm-wave applications and presents the process development of signal routings such as transmission lines and microvias in RDLs as well as through-package vias (TPVs) with via-in-via process. The results suggest that the ultra-thin GPE architecture is a promising packaging technology solution for a variety of applications including high-frequency communications and high-performance computing.

AbstractHearing loss can lead to isolation and social withdrawal. The telephone oftentimes connects persons with hearing loss to society; however, telephone use is impeded by narrow bandwidth, loss of visual cues, electromagnetic interference, and inherent phone-line noise. In the past, research assessing telephone communication has consistently reported that switching from the microphone to a telecoil will typically result in the acoustic signal being discernibly softer. Properly used telecoils improve the signal-to-noise ratio (SNR), decrease the chance for acoustic feedback, and overcome the impact of distance and reverberation creating an opportunity for clearer telephone communication. Little research, however, has examined matching the telecoil frequency response to the prescribed target of the microphone frequency response (National Acoustics Laboratories, Non-Linear, version 1 [NAL-NL1]).The primary goal of this study was to determine if differences exist in speech recognition for sentences (AZ-BIO) and consonant–vowel nucleus-consonant monosyllabic words (CNC) between two telecoil conditions (default and programmed). A secondary goal was to determine if differences exist in speech recognition for sentences between male and female talkers.A single-blinded randomized controlled trial.Twenty experienced adult hearing aid users with bilateral symmetric slight to severe sensorineural hearing loss were recruited from Washington University in St. Louis School of Medicine. In addition, ten normal-hearing participants were recruited to determine the presentation level of the speech stimuli for the hearing aid participants.Participants underwent real-ear measures to program the microphone frequency response of a receiver-in-the-canal hearing aid to NAL-NL1. Using the manufacturer software, one telecoil program remained as the manufacturer default and a second telecoil program was programmed so the sound pressure level for an inductive telephone simulator frequency response matching the microphone’s frequency response to obtain as close to a 0 dB relative simulated equivalent telephone sensitivity value as possible. Participants then completed speech recognition measures including AZ-BIO sentences (male and female talkers) and CNC monosyllabic words and phonemes, using both telecoil programs. A mixed model analysis was performed to examine if significant differences in speech recognition exist between the two conditions and speech stimuli.Results revealed significant improvement in overall speech recognition for the programmed telecoil performance compared with default telecoil performance (p < 0.001). Also, improved performance in the programmed telecoil was reported with a male talker (p < 0.001) and performance for sentences compared with monosyllabic words (p < 0.001) or phonemes (p < 0.001).The programmed telecoil condition revealed significant improvement in speech recognition for all speech stimuli conditions compared with the default telecoil (sentences, monosyllables, and phonemes). Additional improvement was observed in both telecoil conditions when the talker was male.

Measuring systems based on a pair of optical fiber transmitter-receivers are used in medium-voltage testing laboratories wherein the environment of high electromagnetic interference (EMI) is a limitation for using conventional cabling. Nonlinear compensation techniques have been used to limit the voltage range at the input of optical fiber links. However, nonlinear compensation introduces gain and linearity errors caused by thermal drift. This paper presents a method of thermal compensation for the nonlinear circuit used to improve transient signal handling capabilities in measuring system while maintaining low errors in gain and linearity caused by thermal drift.

Background: The electrocardiogram(ECG) has the considerable diagnostic significance, and applications of ECG monitoring are diverse and in wide use. Noises that commonly disturb the basic electrocardiogram are power line interference(PLI), instrumentation noise, external electromagnetic field interference, noise due to random body movements and respiration movements. These noises can be classified according to their frequency content. It is essential to reduce these disturbances in ECG signal to improve accuracy and reliability. The bandwidth of the noise overlaps that of wanted signals, so that simple filtering cannot sufficiently enhance the signal to noise ratio. It is difficult to apply filters with fixed filter co-efficients to reduce these noise. Adaptive filter technique is required to overcome this problem as the filter coefficients can be varied to track the dynamic variations of the signals. Adaptive filter based on the least mean square (LMS) algorithm and recursive least squares (RLS) algorithm are applied to noisy ECG to reduce 50 Hz power line noise and motion artifact noise. Method: ECG signal is taken from physionet database. A ECG signal (without noise) was mixed with constant 0.1 mVp-p 50 Hz interference and motion artifact noise processed with Adaptive filter based on the least mean square (LMS) algorithm and recursive least squares (RLS) algorithm. Simulation results are also shown. Performance of filters are analyzed based on SNR and MSE.

Control of gene expression is crucial for several biotechnological applications, especially for implementing predictable and controllable genetic circuits. Such circuits are often implemented with a transcriptional regulator activated by a specific signal. These regulators should work independently of the host machinery, with low gratuitous induction or crosstalk with host components. Moreover, the signal should also be orthogonal, recognized only by the regulator with minimal interference with the host operation. In this context, transcriptional regulators activated by plant metabolites as flavonoids emerge as candidates to control gene expression in bacteria. However, engineering novel circuits requires the characterization of the genetic parts (e.g., genes, promoters, ribosome binding sites, and terminators) in the host of interest. Therefore, we decomposed the QdoR regulatory system of B. subtilis, responsive to the flavonoid quercetin, and reassembled its parts into genetic circuits programmed to have different levels of gene expression and noise dependent on the concentration of quercetin. We showed that only one of the promoters regulated by QdoR worked well in E. coli, enabling the construction of other circuits induced by quercetin. The QdoR expression was modulated with constitutive promoters of different transcriptional strengths, leading to low expression levels when QdoR was highly expressed and vice versa. E. coli strains expressing high and low levels of QdoR were mixed and induced with the same quercetin concentration, resulting in two stable populations expressing different levels of their gene reporters. Besides, we demonstrated that the level of QdoR repression generated different noise levels in gene expression dependent on the concentration of quercetin. The circuits presented here can be exploited in applications requiring adjustment of gene expression and noise using a highly available and natural inducer as quercetin.

Abstract We numerically demonstrate two types of metasurface absorbers to efficiently absorb digital signals. First, we show that the digital waveforms used in this study contain not only a fundamental wave but also nonnegligible harmonic waves, which limits the absorption performance of a conventional metasurface absorber operating in only a single, finite frequency band. The first type of the proposed absorbers is designed using two kinds of unit cells, each of which absorbs either a fundamental frequency or third harmonic of an incident digital waveform. This dual-band metasurface absorber exhibits absorption performance exceeding that of the conventional metasurface absorber and more strongly dissipates the energy of a digital waveform. In addition, the second type of absorber exploits the concept of nonlinear analogous circuits to convert an incoming wave to a different waveform, specifically, a triangular waveform that has a larger magnitude at a fundamental frequency. Therefore, the incoming waveform is more effectively absorbed by this waveform-conversion metasurface absorber as well. Although still there remain some issues to put these digital signal absorbers into practice, including experimental validation, our results contribute to mitigating electromagnetic interference issues caused by digital noise and realising physically smaller, lighter digital signal processing products for the next generation.

One of the key directions in the development of modern society is the formation of an integrated information space based on the latest information technologies. The widespread use of information technologies and infocommunication networks for the transmission, reception, processing and storage of information in various fields of activity, on the one hand, contributes to an increase in the efficiency of this activity, and on the other hand, it causes the emergence of threats of information leakage through technical channels, which are understood as the uncontrolled dissemination of information signal from its source through the physical environment to a technical means that intercepts information. In the list of threats, an important place is occupied by threats of information leakage through channels of compromising electromagnetic emanations, as well as a result of interference of information signals in power lines of technical means of information processing, connecting lines of auxiliary technical means and systems, ground circuits and extraneous conductors. To protect information from its leakage due to compromising electromagnetic emanations through communications connecting the system blocks of computing facilities with peripheral devices, it is important to analyze the formation of these signals and emissions. The article presents the results of the study of compromising electromagnetic emanations of the USB 2.0 interface, carried out to solve the problems of assessing the security of information at the objects of information activity. The processes of formation of technical channels of information leakage by compromising electromagnetic emanations at use of the USB-interface in structure of control system of information and communication networks are considered. The images of the signal levels of the compromising electromagnetic emanations of the USB 2.0 interface obtained with the spectrum analyzer ROHDE & SCHWARZ FSW 13 (Signal & Spectrum Analyzer) using the R & S Active Dipole Antenna HE527 are shown. As a result of the analysis of the form and spectrum of signals in the USB cable (test mode is off, test mode is on) it is established that in the USB interface there is a constant transmission of service packets to support the interface. When the test mode is turned on, additional pulse sequences appear on the spectrogram. The frequency of the first harmonic for the USB 2.0 interface is in the region of 240 MHz.

Introduction In this article, I explore the phenomenon of augmentation by questioning its representational nature and analyzing aesthetic modes of our interrelationship with the environment. How can senses be augmented and how do they serve as mechanisms of enhancing the feeling of presence? Media art practices offer particularly valuable scenarios of activating such mechanisms, as the employment of digital technology allows them to operate on a more subtle level of perception. Given that these practices are continuously evolving, this analysis cannot claim to be a comprehensive one, but rather aims to introduce aspects of the specific relations between augmentation, sense of proprioception, technology, and art. Proprioception is one of the least detectable and trackable human senses because it involves our intuitive sense of positionality, which suggests a subtle equilibrium between a center (our individual bodies) and the periphery (our immediate environments). Yet, as any sense, proprioception implies a communicational chain, a network of signals traveling and exchanging information within the body-mind complex. The technological augmentation of this dynamic process produces an interference in our understanding of the structure and elements, the information sent/received. One way to understand the operations of the senses is to think about them as images that the mind creates for itself. Artistic intervention (usually) builds upon exactly this logic: representation of images generated in mind, supplementing or even supplanting the existing collection of inner images with new, created ones. Yet, in case of proprioception the only means to interfere with and augment these inner images is on bodily level. Hence, the question of communication through images (or representations) should be extended towards a more complex theory of embodied perception. Drawing on phenomenology, cognitive science, and techno-cultural studies, I focus on the potential of biofeedback technologies to challenge and transform our self-perception by conditioning new pathways of apprehension (sometimes by creating mechanisms of direct stimulation of neural activity). I am particularly interested in how the awareness of the self (grounded in the felt relationality of our body parts) is most significantly activated at the moments of disturbance of balance, in situations of perplexity and disorientation. Projects by Marco Donnarumma, Sean Montgomery, and other artists working with biofeedback aesthetically validate and instantiate current research about neuro-plasticity, with technologically mediated sensory augmentation as one catalyst of this process. Augmentation as Representation: Proprioception and Proprioceptive Media Representation has been one of the key ways to comprehend reality. But representation also constitutes a spatial relation of distancing and separation: the spectator encounters an object placed in front of him, external to him. Thus, representation is associated more with an analytical, rather than synthetic, methodology because it implies detachment and division into parts. Both methods involve relation, yet in the case of representation there is a more distinct element of distance between the representing subject and represented object. Representation is always a form of augmentation: it extends our abilities to see the "other", otherwise invisible sides and qualities of the objects of reality. Representation is key to both science and art, yet in case of the latter, what is represented is not a (claimed) "objective" scheme of reality, but rather images of the imaginary, inner reality (even figurative painting always presents a particular optical and psychological perspective, to say nothing about forms of abstract art). There are certain kinds of art (visual arts, music, dance, etc.) that deal with different senses and thus, build their specific representational structures. Proprioception is one of the senses that occupies relatively marginal position in artistic production (which is exactly because of the specificity of its representational nature and because it does not create a sense of an external object. The term "proprioception" comes from Latin propius, or "one's own", "individual", and capio, cepi – "to receive", "to perceive". It implies a sense of one's self felt as a relational unity of parts of the body most vividly discovered in movement and in effort employed in it. The loss of proprioception usually means loss of bodily orientation and a feeling of one's body (Sacks 43-54). On the other hand, in case of additional stimulation and training of this sense (not only via classical cyber-devices, like cyber-helmets, gloves, etc. that set a different optics, but also techniques of different kinds of altered states of mind, e.g. through psychotropics, but also through architecture of virtual space and acoustics) a sense of disorientation that appears at first changes towards some analogue of reactions of enthusiasm, excitement discovery, and emotion of approaching new horizons. What changes is not only perception of external reality, but a sense of one's self: the self is felt as fluid, flexible, with penetrable borders. Proprioception implies initial co-existence of the inner and outer space on the basis of originary difference and individuality/specificity of the occupied position. Yet, because they are related, the "external" and "other" already feels as "one's own", and this is exactly what causes the sense of presence. Among the many possible connections that the body, in its sense of proprioception, is always already ready for, only a certain amount gets activated. The result of proprioception is a special kind of meta-stable internal image. This image may not coincide with the optical, auditory, or haptic image. According to Brian Massumi, proprioception translates the exertions and ease of the body's encounters with objects into a muscular memory of relationality. This is the cumulative memory of skill, habit, posture. At the same time as proprioception folds tactility in, it draws out the subject's reactions to the qualities of the objects it perceives through all five senses, bringing them into the motor realm of externalizable response. (59) This internal image is not mediated by anything, though it depends directly on the relations between the parts. It cannot be grasped because it is by definition fluid and dynamic. The position in one point is replaced here by a position-in-movement (point-in-movement). "Movement is not indexed by position. Rather, the position is born in movement, from the relation of movement towards itself" (Massumi 179). Philosopher of "extended mind" Andy Clark notes that we should distinguish between a real body schema (non-conscious configuration) and a body image (conscious construct) (Clark). It is the former that is important to understand, and yet is the most challenging. Due to its fluidity and self-referentiality, proprioception is not presentable to consciousness (the unstable internal image that it creates resides in consciousness but cannot be grasped and thus re-presented). A feeling/sense, it is not bound by sensible forms that would serve as means of objectification and externalization. As Barbara Montero observes, while the objects of vision and hearing, i.e. the most popular senses involved in the arts, are beyond one's body, sense of proprioception relates directly to the bodily sensation, it does not represent any external objects, but the sensory itself (231). These characteristics of proprioception help to reframe the question of augmentation as mediation: in the case of proprioception, the medium of sensation is the very relational structure of the body itself, irrespective of the "exteroceptive" (tactile) or "interoceptive" (visceral) dimensions of sensibility. The body is understood, then, as the "body without image,” and its proprioceptive effect can then be described as "the sensibility proper to the muscles and ligaments" (Massumi 58). Proprioception in (Media) Art One of the most convincing ways of externalization and (re)presentation of the data of proprioception is through re-production of its structure and its artificial enhancement with the help of technology. This can be achieved in at least two ways: by setting up situations and environments that emphasize self-perspective and awareness of perception, and by presenting measurements of bio-data and inviting into dialogue with them. The first strategy may be connected to disorientation and shifted perspective that are created in immersive virtual environments that make the role of otherwise un-trackable, fluid sense of proprioception actually felt and cognized. These effects are closely related to the nuances of perception of space, for instance, to spatial illusion. Practice of spatial illusion in the arts traces its history as far back as Roman frescos, trompe l’oeil, as well as phantasmagorias, like magic lantern. Geometrically, the system of the 360º image is still the most effective in producing a sense of full immersion—either in spaces from panoramas, Stereopticon, Cinéorama to CAVE (Computer Augmented Virtual Environments), or in devices for an individual spectator’s usage, like a stereoscope, Sensorama and more recent Head Mounted Displays (HMD). All these devices provide a sense of hermetic enclosure and bodily engagement with its scenes (realistic or often fantastical). Their images are frameless and thus immeasurable (lack of the sense of proportion provokes feeling of disorientation), image apparatus and the image itself converge here into an almost inseparable total unity: field of vision is filled, and the medium becomes invisible (Grau 198-202; 248-255). Yet, the constructed image is even more frameless and more peculiarly ‘mental’ in environments created on the basis of objectless or "immaterial" media, like light or sound; or in installations prioritizing haptic sensation and in responsive architectures, i.e. environments that transform physically in reaction to their inhabitants. The examples may include works by Olafur Eliasson that are centered around the issues of conscious perception and employ various optical and other apparata (mirrors, curved surfaces, coloured glass, water systems) to shift the habitual perspective and make one conscious of the subtle changes in the environment depending on one's position in space (there have been instances of spectators in Eliasson's installations falling down after trying to lean against an apparent wall that turned out to be a mere optical construct.). Figure 1: Olafur Eliasson, Take Your Time, 2008. © Olafur Eliasson Studio. In his classic H2OExpo project for Delta Expo in 1997, the Dutch architect Lars Spuybroek experimented with the perception of instability. There is no horizontal surface in the pavilion; floors, composed of interconnected elliptical volumes, transform into walls and walls into ceilings, promoting a sense of fluidity and making people respond by falling, leaning, tilting and "experiencing the vector of one’s own weight, and becoming sensitized to the effects of gravity" (Schwartzman 63). Along the way, specially installed sensors detect the behaviour of the ‘walker’ and send signals to the system to contribute further to the agenda of imbalance and confusion by changing light, image projection, and sound.Figure 2: Lars Spuybroek, H2OExpo, 1994-1997. © NOX/ Lars Spuybroek. Philip Beesley’s Hylozoic Ground (2010) is also a responsive environment filled by a dense organic network of delicate illuminated acrylic tendrils that can extend out to touch the visitor, triggering an uncanny mixture of delight and discomfort. The motif of pulsating movement was inspired by fluctuations in coral reefs and recreated via the system of precise sensors and microprocessors. This reference to an unfamiliar and unpredictable natural environment, which often makes us feel cautious and ultra-attentive, is a reminder of our innate ability of proprioception (a deeply ingrained survival instinct) and its potential for a more nuanced, intimate, emphatic and bodily rooted communication. Figure 3: Philip Beesley, Hylozoic Ground, 2010. © Philip Beesley Architect Inc. Works of this kind stimulate awareness of both the environment and one's own response to it. Inviting participants to actively engage with the space, they evoke reactions of self-reflexivity, i.e. the self becomes the object of its own exploration and (potentially) transformation. Another strategy of revealing the processes of the "body without image" is through representing various kinds of bio-data, bodily affective reactions to certain stimuli. Biosignal monitoring technologies most often employed include EEG (Electroencephalogram), EMG (Electromyogram), GSR (Galvanic Skin Response), ECG (Electrocardiogram), HRV (Heart Rate Variability) and others. Previously available only in medical settings and research labs, many types of sensors (bio and environmental) now become increasingly available (bio-enabled products ranging from cardio watches—an instance of the "quantified self" trend—to brain wave-controlled video games). As the representatives of the DIY makers community put it: "By monitoring some phenomena (biofeedback) you can train yourself to modulate them, possibly improving your emotional state. Biosensing lets you interact more naturally with digital systems, creating cyborg-like extensions of your body that overcome disabilities or provide new abilities. You can also share your bio-signals, if you choose, to participate in new forms of communication" (Montgomery). What is it about these technologies besides understanding more accurately the unconscious and invisible signals? The critical question in relation to biofeedback data is about the adequacy of the transference of the initial signal, about the "new" brought by the medium, as well as the ontological status of the resulting representation. These data are reflections of something real, yet themselves have a different weight, also providing the ground for all sorts of simulative methods and creation of mixed realities. External representations, unlike internal, are often attributed a prosthetic nature that is treated as extensions of existing skills. Besides serving their direct purpose (for instance, maps give detailed picture of a distant location), these extensions provide certain psychological effects, such as disorientation, displacement, a shift in a sense of self and enhancement of the sense of presence. Artistic experiments with bio-data started in the 1960s most famously with employing the method of sonification. Among the pioneers were the composers Alvin Lucier, Richard Teitelbaum, David Rosenblum, Erkki Kurenemi, Pierre Henry, and others. Today's versions of biophysical performance may include not only acoustic, but also visual interpretation, as well as subtle narrative scenarios. An example can be Marco Donnarumma's Hypo Chrysos, a piece that translates visceral strain in sound and moving images. The title refers to the type of a punishing trial in one of the circles of hell in Dante's Divine Comedy: the eternal task of carrying heavy rocks is imitated by the artist-performer, while the audience can feel the bodily tension enhanced by sound and imagery. The state of the inner body is, thus, amplified, or augmented. The sense of proprioception experienced by the performer is translated into media perceivable by others. In this externalized form it can also be shared, i.e. released into a space of inter-subjectivity, where it receives other, collective qualities and is not perceived negatively, in terms of pressure. Figure 4: Marco Donnarumma, Hypo Chrysos, 2011. © Marco Donnarumma. Another example can be an installation Telephone Rewired by the artist-neuroscientist Sean Montgomery. Brainwave signals are measured from each visitor upon the entrance to the installation site. These individual data then become part of the collective archive of the brainwaves of all the participants. In the second room, the viewer is engulfed by pulsing light and sound that mimic endogenous brain waveforms of the previous viewers. As in the experience of Donnarumma's performance, this process encourages tuning in to the inner state of the other and finding resonating states in one's own body. It becomes a tool for self-exploration, self-knowledge, and self-control, as well as for developing skills of collective being, of shared body-mind topologies. Synchronization of mental and bodily states of multiple people serves here a broader and deeper goal of training collaborative and empathic abilities. An immersive experience, it triggers deep embodied neural circuits, reaching towards the most authentic reactions not mediated by conscious procedures and judgment. Figure 5: Sean Montgomery, Telephone Rewired, 2013. © Sean Montgomery. Conclusion The potential of biofeedback as a strategy for art projects is a rich area that artists have only begun to explore. The layer of the imaginary and the fictional (which makes art special and different from, for instance, science) can add a critical dimension to understanding the processes of augmentation and mediation. As the described examples demonstrate, art is an investigative journey that can be engaging, surprising, and awakening towards the more subtle and acute forms of thinking and feeling. This astuteness and percipience are especially needed as media and technologies penetrate and affect our very abilities to apprehend reality. We need new tools to make independent and individual judgment. The sense of proprioception establishes a productive challenge not only for science, but also for the arts, inviting a search for new mechanisms of representing the un-presentable and making shareable and communicable what is, by definition, individual, fluid, and ungraspable. Collaborative cognition emerging from the augmentation of proprioception that is enabled by biofeedback technologies holds distinct promise for exploration of not only subjective, but also inter-subjective states and aesthetic strategies of inducing them. References Beesley, Philip. Hylozoic Ground. 2010. Venice Biennale, Venice. Clark, Andy, and David J. Chalmers. “The Extended Mind.” Analysis 58.1 (1998):7-19. Donnarumma, Marco. Hypo Chrysos: Action Art for Vexed Body and Biophysical Media. 2011. Xth Sense Biosensing Wearable Technology. MADATAC Festival, Madrid. Eliasson, Olafur. Take Your Time, 2008. P.S.1 Contemporary Art Centre; Museum of Modern Art, New York. Grau, Oliver. Virtual Art: From Illusion to Immersion. Cambridge, Mass.: MIT Press, 2003. Massumi, Brian. Parables of the Virtual: Movement, Affect, Sensation. Durham: Duke University Press, 2002. Montero, Barbara. "Proprioception as an Aesthetic Sense." Journal of Aesthetics and Art Criticism 64.2 (2006): 231-242. Montgomery, Sean, and Ira Laefsky. "Biosensing: Track Your Body's Signals and Brain Waves and Use Them to Control Things." Make 26. 1 Oct. 2013 ‹http://www.make-digital.com/make/vol26?pg=104#pg104›. Sacks, Oliver. "The Disembodied Lady". The Man Who Mistook His Wife for a Hat and Other Clinical Tales. Philippines: Summit Books, 1985. Schwartzman, Madeline, See Yourself Sensing. Redefining Human Perception. London: Black Dog Publishing, 2011. Spuybroek, Lars. Waterland. 1994-1997. H2O Expo, Zeeland, NL.