Spurious Emissions Research Articles

A Functional Failure Analysis Method of Identifying and Mitigating Spurious System Emissions From a System of Interest in a System of Systems

Abstract Increasingly tight coupling and heavy connectedness in system of systems (SoS) present new problems for systems’ designers and engineers. While the failure of one system within a loosely coupled SoS may produce little collateral damage beyond a loss in SoS capability, a highly interconnected SoS can experience significant damage when one member system fails in an unanticipated way. It is therefore important to develop systems that are “good neighbors” with the other systems in an SoS by failing in ways that do not further degrade an SoS’s ability to complete its mission. This paper presents a method to (1) analyze a system of interest (SoI) for potentially harmful spurious system emissions (failure flows that exit the SoI’s system boundary and may cause failure initiating events in other systems within the SoS) and (2) choose mitigation strategies that provide the best return on investment for the SoS. The method is intended for use during the system architecture phase of the system design process when functional architectures are being developed, and analysis of alternatives and trade-off studies are being conducted2.

A Mixed-Signal Adaptive Ripple Canceler for Switching Regulators Providing 18 dB-24 dB of Ripple Rejection up to 1 MHz

A mixed-signal adaptive ripple canceller for reducing switching noise and spurious emissions in switching regulators is presented. The proposed mixed-signal ripple suppression technique tracks and cancels the switching noise by utilizing two schemes: A primary mixed-signal adaptive ripple canceller that provides large signal ripple cancellation up to 20 dB, and an auxiliary linear amplifier-based ripple canceller that minimizes the residual ripple content, achieving a combined ripple rejection of 24 dB. Proposed approach operates without the need for external components, reducing overall printed circuit board area without loss of efficiency. The adaptive ripple canceller is designed and fabricated in a 250 nm CMOS process with four levels of metal. The ripple-canceller is integrated with an on-chip buck regulator to characterize its rejection effectiveness. The ripple canceller can also be utilized as a stand-alone ripple cleaner module with an external commercial-off-the-shelf (COTS) switching regulator. The proposed ripple canceller can track and cancel power supply ripple up to 1 MHz with 24 dB rejection and reduces ripple content up to fourth harmonic by at least 20 dB while supporting dc loads up to 1 A and ripple currents up to 350 mApk-pk. The proposed approach achieves 30% lower quiescent current than using a linear low-dropout regulator without the need for any external components.

Dust emission and transport in Northwest China: WRF-Chem simulation and comparisons with multi-sensor observations

In this study, the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is employed to simulate a dust process in Northwest China during May 2018. The model's ability to simulate the dust process in Northwest China is firstly evaluated using various satellite-retrieved and observational data, including satellite-retrieved aerosol optical depth (AOD), extinction coefficient and dust index, as well as observational wind field, precipitation and particulate matter with particle size below 10 mic (PM10) mass concentration at surface. The four-dimensional assimilation method is also used to optimize meteorological data and effectively improve the simulation of the dust process. The comparisons between the simulations based on five dust emission schemes within WRF-Chem and the observations show that, the Shao01 scheme overall has good performance in simulating the emission flux, the spatial pattern of source region, as well as the spatiotemporal variation of dust mass concentration, during this dust process. In comparison to Shao01, the GOCART AFWA and Shao04 schemes can also produce quite similar spatial pattern of dust source region, but tend to overestimate or underestimate dust emission and mass concentration. The Shao11 scheme fails to simulate the dust process since the importance of the fully disturbed particle size distribution is omitted. It is also noted that the GOCART scheme can well reproduce dust emission processes under weak wind erosion but underestimate dust emission flux under strong wind erosion. In addition, the GOCART scheme has produced some spurious emissions and thus blurred the distribution of dust source region. The Shao01 simulation was found to reasonably reproduce the spatial distribution and magnitude of the satellite-retrieved AOD and vertical profile of extinction coefficient, as well as the PM10 mass concentration at surface. Northwest China is covered by mountains, basins, deserts and other landforms, thus the complex terrain is one of the key factors to influence the dust process over the region. Our study shows that after being emitted, the airborne dust transported toward the east and west. The dust to the east was diffused rapidly, but the portion toward the west was blocked and accumulated at the edges of the mountains and thus produced dust weather characterized by high dust concentration and long lifetime. The dust accumulated at the edges of the mountains could reach an altitude of more than 6 km due to wind and thermal effect, and finally arrive at Tibetan Plateau and eastern China.

Development and performance of high voltage electrodes for the LZ experiment

LZ is a next-generation dark matter search experiment designed to significantly extend our sensitivity to WIMP dark matter candidates. At the core of the LZ detector is a dual-phase xenon time projection chamber (TPC) with a 7-ton active mass. To observe signals from low-energy nuclear recoils, including WIMP-xenon scatters, four custom-woven wire-mesh grids of 1.5m diameter establish strong electric fields in the TPC to drift ionization electrons across the volume and extract them from the liquid surface. As a result of the high electric fields, dielectric breakdown between high voltage surfaces and spurious electron emission from regions of high surface fields are major concerns. To mitigate these risks, an R&D program exploring design geometry in high field regions, cleanliness procedures, and surface treatments has been carried out using a comprehensive suite of three mid-scale dual- and single-phase xenon detectors. These proceedings will summarize the design and construction of the LZ grids, and several aspects of the high voltage performance seen in the testing program.

RESULTS OF MODELING, DESIGNING AND DEVELOPMENT OF BAND-PASS ELECTRIC FILTER WITH CROSS-LINKS IN WIDE RANGE OF ULTRA HIGH FREQUENCY BANDS

The provided analysis shows the need to ensure non-interference operation of radio electronic facilities (REFs) by eliminating the incompatible radio technologies in the adjacent frequency bands or by minimizing interference as far as possible. A presented example based on the cellular communication systems suggests that one of the factors influencing the size of a guard interval is the need to ‘filter-out’ nearby radio technologies operating in opposite directions of transmission. In such instances, filters shall be used to avoid interference. Filters will allow, in the first place, to create necessary attenuation in the reception band of BS of nearby radio technology to suppress out- of-band and spurious emissions, furnishing by BS own transmitter; and in the second place, to create attenuation in the transmission band of nearby radio technology in order to reduce signals coming from BS transmitters of nearby radio technology at the input of own BS receiver. Additional high slope AFR filters may be required for both the BS transmitters and BS receivers in some frequency ranges in Ukraine. There is one more precondition for usage of high slope AFR filters having the ability to suppress main emission of transmitters by values of 30-40 dB as follows: appropriate radio frequency control and regulatory authorities are required to apply the measuring equipment within dynamic range of 80 dB. The simplified 3D filter models on 9 coaxial resonators with high Q factor which are described in the article are prepared with the help of AWR Microwave office and CST Studio Suite software tools. The simulation of AFR and frequency response for such parameter as filter reflection coefficient is also described in the article. The results of design and research concerning band-pass electric filters that have been obtained on the basis of application of the low-frequency filter prototype method are presented in the article. Prototype models of band-pass electric filters with cross-links in wide range of UHF bands (820–843 MHz and 890–915 MHz, 1920–1980 MHz and 2510–2570 MHz) are designed and produced. As a result of measurements of AFR and frequency response for the filter reflection coefficient, the attenuation within the pass-band frequency range of these filters equals to 1.5–2.0 dB; the attenuation of input signals referring to out-of-band emissions equals to 30–75 dB; the filter reflection coefficient is within minus 13 dB.

DESIGN AND MODELING OF BAND-PASS FILTERS ON COAXIAL RESONATORS FOR THE CELLULAR COMMUNICATION SYSTEMS

The provided analysis shows the need to ensure non-interference operation of radio electronic facilities (REF) by eliminating the incompatible radio technologies in the adjacent frequency bands or by minimizing interference as far as possible. A presented example based on the cellular communication systems suggests that one of the factors influencing the size of a guard interval is the need to 'filter-out' nearby radio technologies operating in opposite directions of transmission. In such instances, filters shall be used to avoid interference. Filters will allow, in the first place, to create necessary attenuation in the reception band of the base station (BS) of nearby radio technology to suppress out-of-band and spurious emissions, furnishing by BS own transmitter; and in the second place, to create attenuation in the transmission band of nearby radio technology to reduce signals coming from BS transmitters of nearby radio technology at the input of own BS receiver. Additional high slope AFR filters may be required for both the BS transmitters and BS receivers in some frequency ranges in Ukraine. This article contains the results of modeling, designing, experimental research and testing of the band-pass electric filter with cross-links in a wide range of UHF bands (820-843 MHz and 890-915 MHz, 1920-1980 MHz and 2510-2570 MHz) using the low-frequency filter prototype method.

Функциональные модели защиты информации от утечки за счет побочных электромагнитных излучений объектов информатизации

Функциональные модели защиты информации от утечки за счет побочных электромагнитных излучений объектов информатизации

Performance Evaluation of Digital Pre-Distortion Technique using Low-Complexity and Low-Precision ADC

This paper analyzes the Digital Pre-Distortion linearization technique using a low-precision Analog-to-Digital Converter (ADC). The output of a power amplifier exhibits various spurious emissions, spectral regrowth and intermodulation distortion (IMD) products due to its non-linear behavior. So, to preserve the performance of power amplifier, linearization becomes mandatory. Digital Pre-Distortion does the training on the output of the power amplifier (distorted signal) and generates exactly the inverse characteristics to that of power amplifier. Their cascading results into a linear response. In practical systems, the output of power amplifier has to go through an analog-to-digital converter for digital processing and a low-resolution ADC results in the degradation of the signal and affects the DPD performance. But a low-resolution ADC not only reduces the computational complexity in the digital processing but it also provides lower power consumption and costs less because less hardware would be required. In this work, the aim is to find the precision up to which ADC resolution can be reduced without affecting the DPD performance in a significant manner. This paper evaluates the performance of two DPD systems - Full-band DPD and Sub-band DPD and from simulations, it is observed that for a full-band DPD, 1-bit ADC can be reliably used and for a sub-band DPD, single bit to 4-bits ADC can be used.

Nonintrusive Load Monitoring Based on Complementary Features of Spurious Emissions

In this paper, a novel method that utilizes the fractional correlation-based algorithm and the B-spline curve fitting-based algorithm is proposed to extract the complementary features for detecting the operating states of appliances. The identification of appliance operating states is one of the key parts for nonintrusive load monitoring (NILM). Considering the individual spurious emissions generated because of nonlinear components in each electronic device, the spurious emissions from the power cord can be picked up to solve the problem of data storage. Five types of common household appliances are considered in this study. The fractional correlation-based algorithm and B-spline curve fitting-based algorithm are used to extract two groups of complementary features from the spurious emissions of those five types of appliances. The experimental results show that the feature vectors extracted using the proposed method are obviously distinguishable. In addition, the features extracted show a good long-time stability, which is verified through a five-day experiment. Finally, based on support vector machine (SVM) and Dempster–Shafer (D-S) evidence theory, the identification accuracy reaches 85.5% using a combining classifier incorporated with the features extracted from the proposed methods.

Influence of the Method of Colors on Levels of Electromagnetic Emissions From Video Standards

Every electronic device that processes information becomes a source of spurious emissions. These emissions can be used in the process of electromagnetic eavesdropping, resulting in the possibility of obtaining information in a non-invasive manner. The graphic tracks of information systems are particularly sensitive sources of such emissions. This paper analyzes the levels of electromagnetic interference from two graphic standards: video grafics array (VGA) and digital video interface (DVI). The DVI standard, due to the assumptions made by the Digital Display Working Group, was to replace the analog VGA standard and increase the electromagnetic safety of transmitted graphic data. However, the reality and ongoing research did not confirm this. The DVI digital standard, as a source of spurious emissions, must be protected in the same way as the VGA standard. This paper analyzes the impact of the color method on levels of electromagnetic interference for the two considered graphic standards. The color method (the right color for the background and text) is one of the solutions that can counteract the process of electromagnetic eavesdropping. The proper selection of colors can limit the level of electromagnetic interference but only in the case of the VGA standard (change in the amplitude of the voltage of the electrical signal). The DVI standard, due to a different way of color coding (the value of voltage amplitude of the electrical signal is constant; the shape of the signal changes), does not show any relation between the choice of background colors and text or the level of generated electromagnetic interference. Very often, this interference has the characteristics of information being processed and becomes valuable in the process of electromagnetic infiltration. That is why, the analog VGA standard is still widely used in information systems, where the most important aspect is the protection of information against electromagnetic penetration.

Adaptive Cancellation of Digital Power Amplifier Receive Band Noise for FDD Transceivers

In frequency division duplex systems, spurious emission from transmitter (TX) can fall into receive band and lead to significant receiver desensitization. In this paper, a DSP-based solution that relies on a linear auxiliary receiver to cancel receive band noise (RxBN) from the received signal is demonstrated. This technique allows reduction of duplexer rejection requirements in the receiver band, and associated reduction of insertion loss in the TX band, thus resulting in high-power amplifier (PA) efficiency and small duplexer footprint. The PA architectures that inherently have high RxBN (such as envelope tracking and the digitally modulated PAs) can substantially benefit from this technique. Experimental results based on off-the-shelf system implementation are demonstrated using a digital PA, and more than 22 dB cancellation is achieved to reduce RxBN below thermal noise floor at 836 MHz with 45 MHz duplex spacing.

Токоперехватывающие сетки из анизотропного пиролитического графита в электронных пушках с металлопористым катодом

Presented the results of experimental researches of anisotropic pyrolitic graphite application as a grid structure in high-power devices with the dispenser cathode. The emission characteristics of molybdenum, hafnium and anisotropic pyrolitic graphite in diodes and electron guns versus high-power electron flow, dissipated on test specimen and cathode temperature are given in the article. Also the grid structures made of anisotropic pyrolitic graphite are able to dissipate power of the electron flow 20 times more than grids made of molybdenum and 9 times more than grids made of hafnium without occurrence of spurious thermionic emission are shown in the article.

Characterization of non-intentional emissions from distributed energy resources up to 500 kHz: A case study in Spain

Narrow Band Power Line Communications (NB-PLC) systems are currently used for smart metering and power quality monitoring as a part of the Smart Grid (SG) concept. However, non-intentional emissions generated by the devices connected to the grid may sometimes disturb the communications and isolate metering equipment. Though some research works have been recently developed to characterize these emissions, most of them have been limited to frequencies below 150 kHz and they are mainly focused on in-house electronic appliances and lightning devices. As NB-PLC can also be allocated in higher frequencies up to 500 kHz, there is still a lack of analysis in this frequency range, especially for emissions from Distributed Energy Resources (DERs). The identification and characterization of the emissions is essential to develop solutions that avoid a negative impact on the proper performance of NB-PLC.In this work, the non-intentional emissions of different types of DERs composing a representative microgrid have been measured in the 35–500 kHz frequency range and analyzed both in time and frequency domains. Different working conditions and coupling and commutation procedures to mains are considered in the analysis. Results are then compared to the limits recommended by regulatory bodies for spurious emissions from communication systems in this frequency band, as no specific limits for DERs have been established. Field measurements show clear differences in the characteristics of non-intentional emissions for different devices, working conditions and coupling procedures and for frequencies below and above 150 kHz. Results of this study demonstrate that a further characterization of the potential emissions from the different types of DERs connected to the grid is required in order to guarantee current and future applications based on NB-PLC.

Study and mitigation of spurious electron emission from cathodic wires in noble liquid time projection chambers

Noble liquid radiation detectors have long been afflicted by spurious electron emission from their cathodic electrodes. This phenomenon must be understood and mitigated in the next generation of liquid xenon (LXe) experiments searching for WIMP dark matter or neutrinoless double beta decay, and in the large liquid argon (LAr) detectors for the long-baseline neutrino programmes. We present a systematic study of this spurious emission involving a series of slow voltage-ramping tests on fine metal wires immersed in a two-phase xenon time projection chamber with single electron sensitivity. Emission currents as low as 10−18 A can thus be detected by electron counting, a vast improvement over previous dedicated measurements. Emission episodes were recorded at surface fields as low as ∼ 10 kV/cm in some wires and observed to have complex emission patterns, with average rates of 10–200 counts per second (c/s) and outbreaks as high as ∼ 106 c/s. A fainter, less variable type of emission was also present in all untreated samples. There is evidence of a partial conditioning effect, with subsequent tests yielding on average fewer emitters occurring at different fields for the same wire. We find no evidence for an intrinsic threshold particular to the metal-LXe interface which might have limited previous experiments up to fields of at least 160 kV/cm. The general phenomenology is not consistent with enhanced field emission from microscopic filaments, but it appears instead to be related to the quality of the wire surface in terms of corrosion and the nature of its oxide layer. This study concludes that some surface treatments, in particular nitric acid cleaning applied to stainless steel wires, can bring about at least order-of-magnitude improvements in overall electron emission rates, and this should help the next generation of detectors achieve the required electrostatic performance.

Fully-digital transmitter architectures and circuits for the next generation of wireless communications

The rapidly evolving trend for increased data rates in today’s and future cellular communication systems poses extreme difficulties for developers of cellular transceivers. A multitude of standards ranging from legacy 2G to the upcoming, yet to be defined, 5G needs to be supported across a broad but fragmented frequency spectrum. Higher data throughput necessitates higher bandwidths, increased number of aggregated carriers, and more complex of modulation schemes. Capable transmitters must exhibit highest in-band performance, e.g. linearity and error vector magnitude. Simultaneously, out-of-band performance, like noise and spurious emissions, is crucial to co-exist with other wireless channels, such as the transceiver’s receivers and other participants. While a “more of everything” is expected, competitive solutions for the wireless market require a constant decrease in silicon area, bill of materials, and especially power consumption. This paper presents the evolution of integrated transmitter architectures facing the above challenges: From conventional analog direct conversion transmitters to fully-digital direct modulation RF transmitters, challenges and benefits are highlighted, presenting modern architectures that benefit from the most advanced technology nodes while supporting upcoming 5G cellular wireless communications.

Анализ утечек информации на основе побочных электромагнитных излучений

Анализ утечек информации на основе побочных электромагнитных излучений

A Single-Ended Modified Class-E PA With HD2 Rejection for Low-Power RF Applications

This letter presents a fully integrated single-ended power amplifier for ultralow-power applications. The single-ended configuration is possible due to a choke-inductor less output network capable of rejecting the second-harmonic emission. A switching duty-ratio lower than 50% avoids the impedance transformation output network traditionally required for proper class-E operation. At 2.45 GHz, the PA (including the driver) delivers 1.4 dBm to a $50~ {\Omega }$ load and achieves an overall efficiency of 51% while complying with the spurious emission regulation. The prototype was fabricated in $0.13~ {\mu }\text{m}$ CMOS.

Low-complexity, Multi Sub-band Digital Predistortion

The nonlinearities of power amplifiers combined with non-contiguous transmissions found in modern, frequency-agile, wireless standards create undesirable spurious emissions through the nearby spectrum of data carriers. Digital predistortion (DPD) is an effective way of combating spurious emission violations without the need for a significant power reduction in the transmitter leading to better power efficiency and network coverage. In this paper, an iterative, multi sub-band version of the sub-band DPD, proposed earlier by the authors, is presented. The DPD learning is iterated over intermodulation distortion (IMD) sub-bands until a satisfactory performance is achieved for each of them. A sequential DPD learning procedure is also presented to reduce the hardware complexity when higher order nonlinearities are incorporated in the DPD learning. Improvements in the convergence speed of the adaptive DPD learning are also achieved via incorporating a variable learning rate and interpolation of previously trained DPD coefficients. A WarpLab implementation of the proposed DPD is also shown with excellent suppression of the targeted spurious emissions.

Compact substrate integrated waveguide mono-pulse antenna array

A compact monopulse antenna array based on substrate integrated waveguide technology is presented through this article. The design is fabricated on Printed Circuit Board (PCB) technology consisting of a double-layered 8-cell array antenna with a slot in the middle-ground metal used for aperture-coupling excitation and reducing unwanted spurious emissions from feed network. The Impedance bandwidth and AR bandwidth are enhanced due to optimal feed network, including Rat-Race coupler to generate sum and difference patterns for mono-pulse applications operating at 10 GHz. The prototype of the proposed antenna with the size of 124*25 mm2 is fabricated and tested. Measured results compared very well to simulation results obtained by CST microwave studio and show −10-dB impedance bandwidth of 4% and −22 dB null-depth in difference mode.

Parallel Digital Predistortion Design on Mobile GPU and Embedded Multicore CPU for Mobile Transmitters

Digital predistortion (DPD) is a widely adopted baseband processing technique in current radio transmitters. While DPD can effectively suppress unwanted spurious spectrum emissions stemming from imperfections of analog RF and baseband electronics, it also introduces extra processing complexity and poses challenges on efficient and flexible implementations, especially for mobile cellular transmitters, considering their limited computing power compared to basestations. In this paper, we present high data rate implementations of broadband DPD on modern embedded processors, such as mobile GPU and multicore CPU, by taking advantage of emerging parallel computing techniques for exploiting their computing resources. We further verify the suppression effect of DPD experimentally on real radio hardware platforms. Performance evaluation results of our DPD design demonstrate the high efficacy of modern general purpose mobile processors on accelerating DPD processing for a mobile transmitter.