EMC-aware analysis and design of a low-cost receiver circuit under injection locking and pulling

In low-cost receiver applications, the preselect filter is often omitted in order to reduce the footprint of the total system. However, the immunity of the receiver can be severely compromised by this approach. This paper focuses on the effects of co-located sources on the local oscillator (LO), specifically injection locking and pulling. To this end, a low-cost radio receiver (RF) front-end is designed for operation in the 2 : 4 5 GHz industrial, scientific and medical (ISM) radio band. In addition to the effects on the oscillator, the consequences on the receiver's performance are evaluated as well. For the first time in literature, this work demonstrates the critical necessity to take the potentially detrimental effects caused by injection locking and pulling into account during Electromagnetic Compatibility (EMC)-aware design

Electromagnetic compatibility aware design and testing of intermodulation distortion under multiple co-located sources illumination

Current electromagnetic immunity tests mainly rely on single-frequency sources. However, the evolution of electronic systems leads to miniaturisation and low-cost solutions, in which filters are omitted in front of active non-linear components, also for efficiency reasons. As a result, intermodulation products may leak into the band of operation. The authors propose a comprehensive strategy consisting of design and test methodologies to evaluate in-the-band leakage of out-of-band undesired components, using multiple-tone excitation and relying on an anechoic chamber as test facility. The aim of this study is to demonstrate that an anechoic chamber together with a dual-source network analyser represents an optimal facility to investigate signal integrity issues owing to leakage of intermodulation products

Partial Relaxation Approach: An Eigenvalue-Based DOA Estimator Framework

In this paper, the partial relaxation approach is introduced and applied to DOA estimation using spectral search. Unlike existing methods like Capon or MUSIC which can be considered as single source approximations of multi-source estimation criteria, the proposed approach accounts for the existence of multiple sources. At each considered direction, the manifold structure of the remaining interfering signals impinging on the sensor array is relaxed, which results in closed form estimates for the interference parameters. The conventional multidimensional optimization problem reduces, thanks to this relaxation, to a simple spectral search. Following this principle, we propose estimators based on the Deterministic Maximum Likelihood, Weighted Subspace Fitting and covariance fitting methods. To calculate the pseudo-spectra efficiently, an iterative rooting scheme based on the rational function approximation is applied to the partial relaxation methods. Simulation results show that the performance of the proposed estimators is superior to the conventional methods especially in the case of low Signal-to-Noise-Ratio and low number of snapshots, irrespectively of any specific structure of the sensor array while maintaining a comparable computational cost as MUSIC.Comment: This work has been submitted to IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Улучшение точности пеленгатора беспилотного вертолета за счет использования виртуальной антенной решетки

This work is devoted to studying the possibility of applying the theory of "virtual" antenna arrays (VAR) to reduce the direction finder error. The case under consideration refers to the direction finder, which is mounted on an unmanned helicopter (UAV). The analysis is performed in the most problematic resonance region of wave scattering on the analyzed electrodynamic object. Based on the data obtained, conclusions are drawn about the prospects of using the VAR apparatus to improve direction finding accuracy.Данная работа посвящена изучению возможности применения аппарата теории «виртуальных» антенных решеток (ВАР) для уменьшения погрешности пеленгования. Рассматриваемый случай относится к пеленгатору, который установлен на беспилотном вертолете (БПЛА). Анализ производится в наиболее проблемной резонансной области рассеяния волн на анализируемом электродинамическом объекте. По полученным данным сделаны выводы о перспективности применения аппарата ВАР для повышения точности пеленгования.Исследование выполнено за счет гранта Российского научного фонда (проект №19-79-10109)

Evaluation of the Effectiveness of Hands-On Corrosion Control Training Using Metered Resistance Measurements to Assess Sailors\u27 Comprehension

The problem of this study was to evaluate the success of combat systems topside preservation training using a cost effective method to self-assess the efficiency of shipboard corrosion control procedures

Time-domaint emi measurement system for conducted emissions meaurements

Desenvolupament d'un sistema de mesura EMI basat en un osciloscopiIn Electromagnetic Compatibility emission measurements, and particularly the emissions tests, a common problem takes place when equipment producing intermittent disturbances is measured according to standard procedures. In many cases, it is impossible to capture the maximum emission using conventional receivers with only one or several sweeps. This work aims to study and propose a measurement method that provides a solution to this problem A significant measurement improvement is possible when time-domain captures and post-processing implementing fast Fourier transform (FFT) are used to obtain the frequency spectrum. In addition, the proposed time-domain method offers some advantages as the possibility to capture all the spectrum frequency range of one single event and evaluate rapidly all the different functional modes of a complex EUT, the cost and the possibility to do a pre-analysis of the interference before the measurement. In this report, the time-domain method is described and validated for conducted emissions test. For the validation proposes, a multisine signal and other equipment are measured using the developed method and the results are compared with results acquire from an EMI receiver. Finally, after validation, the time-domain method is applied to complex equipment observing the main advantages that the developed method provides

Time-domaint emi measurement system for conducted emissions meaurements

Desenvolupament d'un sistema de mesura EMI basat en un osciloscopiIn Electromagnetic Compatibility emission measurements, and particularly the emissions tests, a common problem takes place when equipment producing intermittent disturbances is measured according to standard procedures. In many cases, it is impossible to capture the maximum emission using conventional receivers with only one or several sweeps. This work aims to study and propose a measurement method that provides a solution to this problem A significant measurement improvement is possible when time-domain captures and post-processing implementing fast Fourier transform (FFT) are used to obtain the frequency spectrum. In addition, the proposed time-domain method offers some advantages as the possibility to capture all the spectrum frequency range of one single event and evaluate rapidly all the different functional modes of a complex EUT, the cost and the possibility to do a pre-analysis of the interference before the measurement. In this report, the time-domain method is described and validated for conducted emissions test. For the validation proposes, a multisine signal and other equipment are measured using the developed method and the results are compared with results acquire from an EMI receiver. Finally, after validation, the time-domain method is applied to complex equipment observing the main advantages that the developed method provides

The direction finder based on the passive multichannel detection of the electromagnetic signal

Пасивно одређивање правца долазећег електромагнетског таласа (passive direction finding - DF) је једна од техничких дисциплина стандардно примењивана у различитим цивилним и војним областима. Типичан пример су пасивни системи за рану детекцију борбене технике која емитује електромагнетско зрачење, као што су летелице или пловила са активираним радарима. У области цивилне примене, употреба DF-а је много разноврснија и масовнија, па се такви системи рутински користе у сврху детекције покретних и стационарних извора зрачења, препознавања и отклањања интерференције у радио-везама, лоцирању неауторизованих предајника, у сигурносним и безбедносним сервисима, итд. Због широке области примене, DF системи могу бити различитих карактеристика, као што су: а) портабилност – могућност интеграције уређаја у мале преносиве системе, или мале покретне системе (беспилотна летелица, лако теренско возило, патролни чамац, и др.); б) рад у реалном времену; в) детекција зрачења на више фреквенцијских канала, итд. Да би се испунили тако специфични захтеви, потребно је системски приступити дизајну, што је главна тема докторске дисертације. Како је за аквизицију било које физичке величине потребан одговарајући сензор, аквизиција електромагнетских таласа, постиже се употребом одговарајућих антена, које су у DF техникама типично интегрисане у одговарајући антенски низ. За примену дефинисану у дисертацији, постоји више типова погодних антена. Са циљем селекције одговарајуће антене направљен је преглед најпогодније класе антена – антене хорн типа, и закључено је да је пирамидални хорн најбоље решење. Циљ метода процесирања сигнала добијених са антенског низа као сензора је одређивање правца долазећег електромагнетског сигнала. Могу да буду реализоване различитим типовима алгоритама, па се сходно томе методи међусобно и разликују. Иако постоје супер-резолуционе технике које дају најбоље резултате по питању резолуције, оне нису ефикасне и погодне за рад у портабилним системима, тако да је за дизајн одабрана једна од класичних техника амплитудског типа. Анализиране су основне технике амплитудског типа и одабрана је најпогоднија са становишта ефикасности хардверске и софтверске реализације, као и са становишта уведеног критеријума – амплитудског динамичког опсега. Одређивање правца електромагнетског сигнала из једног извора, уколико нема додатних нарушавајућих фактора, релативно је лако решив проблем. Озбиљан проблем настаје када се ради о више извора и који су при том физички блиски, па одређивања правца за сваки од њих може да буде у општем случају нерешив. Супер-резолуциони методи, судећи према литератури, могу да реше тај проблем у великом броју случајева, али по цену брзине, величине опреме, потрошње енергије, итд. Ако је потребно портабилно решење онда је тај проблем у основи нерешив. У пракси, физички блиски извори емитују зрачење на различитим фреквенцијским каналима, па је сукцесивном детекцијом по сваком каналу могуће детектовати и све такве изворе. Такав поступак је назван вишеканална детекција. Пошто се антенски низ као сензор користи на више фреквенција, његове карактеристике нису исте за сваки фреквенцијски канал. Уз то елементи антенског низа, у општем случају, немају идентичне карактеристике, без обзира на исту геометрију. Због тога је у дисертацији предложен поступак калибрације по свим антенама, и по свим фреквенцијским каналима, као и формирање одговарајуће табеле претраживања која омогућује касније брзо процесирање података. Теоретски, за дефинисану примену, сваки циркуларни антенски низ са усмереним антенама прилагођеним за дефинисани фреквенцијски опсег, могао би да послужи сврси. Међутим како је у питању портабилна примена, циљ је уклапање у задате димензије, односно минимизација габарита и потребног броја елемента антенског низа. Због тога је дефинисана оригинална процедура пројектовања пирамидалних хорн антена, која редефинише стандардни критеријум оптималности, и уводи додатне критеријуме који оптимизују саме антене по питању електричних и механичких карактеристика, као и комплетан антенски низ по питању броја употребљених елемента. Комплетан DF систем је реализован применом савремене аналогно-дигиталне методологије пројектовања електронских система, као и применом робусних софтверских решења. Сви блокови система, њихова функција и реализација детаљно су описани у дисертацији. За реализовани систем и процењену вероватноћу грешака које се генеришу током рада, израчуната је вероватноћа исправне детекције. Одређене су метролошке карактеристике реализованог DF система, мерењем карактеристика појединих склопова система и целог система у целини. Израчунате су мерне несигурности како за појединачне склопове, тако и за цео систем, чиме је дато виђење употребне вредности система.Passive radio direction finding DF is a technical discipline commonly used in many civil and military applications. Typical applications are passive early warning systems, such are aircrafts and vessels equipped with radars. In area of civil applications, DF usage is much more manifold and widespread: such systems are used for detection of moving or stationary radiation sources, in reconnaissance and cleaning interference in radio communications, localization of non-authorized transmitters, in intelligent and security systems, etc. According to widespread application area, DF systems might have different characteristic, such are: a) portability – ability of integration into small transferable or mobile systems (unmanned aircraft, light infantry vehicle, patrol boat, etc.); b) real time operation; c) different channel signals detection, etc. With an aim to be able to achieve all specific DF features, it is mandatory to perform a systematic design, what is the main topic of this doctoral dissertation. For the acquisition of any physical signal, appropriate sensor is required. For the case of acquisition of the electromagnetic waves in DF techniques, the sensor is based on convenient antenna, typically organized in corresponding antenna array. For the application given in the dissertation, there are several suitable types of antennas. In order to select appropriate antenna, an overview of all suitable antennas types – horn antennas, are given, and the conclusion is that the most suitable selection is the pyramidal horn antenna. The purpose of processing signals obtained from the antenna array as a sensor, is to determine the direction of the incoming electromagnetic signal. The processing can be achieved by several techniques, and accordingly, each differ one to another. Although, there are super-resolution techniques that provides the best results in terms of resolution, they are not efficient and suitable for portable systems applications, thus, the classical techniques with amplitude detection are selected for consideration. Basic amplitude detection techniques are analysed, and one is selected as the most suitable from the point of the software and hardware efficiency and implementation, same as from the point of the introduced criterion - amplitude dynamic range. Determination of an electromagnetic wave Direction, from unique radiation source, with no interfering conditions, is a quite easy task. The problem arises when it comes to presence of multiple, physically very close, radiation sources, so in general, determination of direction, per each of them, might be unsolvable. Super-resolution methods, according to literature, are able to solve such tasks in most of cases, for the price of speed, equipment size, energy consumption, etc. If a portable solution is requested, then this problem is essentially unsolvable. In practice, physically close sources radiate at different frequency channels, so by successive detection on each channel it is possible to detect all possible sources. Such a procedure is called multichannel detection. Since the antenna array, considered as a sensor, is used on multiple frequencies, its characteristics are not the same for each frequency channel. In addition, the elements of an antenna array do not have identical characteristics in general, regardless of the same geometry. Therefore, in the dissertation, a calibration procedure is proposed for all antennas, and at all frequency channels. Accordingly, constitution of lookup table that allows, efficient data processing is proposed. Theoretically, for a defined application, any circular antenna array with directional antennas adapted for the defined frequency range can be applied. However, the portable application is concerned, so the goal is to fit it into the given dimension, that is, minimize dimension and number of antenna array elements. For this reason, an original pyramidal horn antenna design procedure is defined, which redefines the standard optimization criterion, and introduces additional criteria for antenna optimization, in terms of electrical and mechanical characteristics, as well as the antenna array optimization in term of number of elements. The complete DF system was realized using the modern mix-signal electronic systems design methodology, and by applying the robust software solutions. Detail description of all system blocks, their function and realization is given in the dissertation. Using the estimated probability of errors generated during operation, the probability of correct detection is calculated. For the case of designed system, and the estimated probability of errors, the probability of correct detection is evaluated. The metrology characteristics of the realized DF system are determined, by measuring the characteristics of individual system components and the entire system itself. Measurement uncertainty for individual components and entre system are calculated, demonstrating the system quality value

Wideband reconfigurable vector antenna for 3-D direction finding application

Direction finding plays a crucial role in various civilian and military applications, related to either radionavigation or radiolocation. Most of the direction finding antennas operate over a wide frequency band, but only a minority of them enable the direction of arrival estimation of an incoming electromagnetic field over a 3-D angular coverage (i.e., estimation of both azimuth and elevation angles). An original approach to obtain a 3-D angular coverage consists in measuring the six components of the incident electromagnetic field through a so-called vector antenna. The aim of this Ph.D. is to design a passive, compact and wideband vector antenna in order to cover a maximum of applications. Two vector antennas have been designed, manufactured and experimentally characterized. Unlike conventional topology, they enable the measurement of the components of an incoming electromagnetic field thanks to the radiation pattern reconfigurability of an original arrangement of Vivaldi antennas. The first prototype is mounted over a finite metallic support and enables the direction of arrival estimation of vertically-polarized electromagnetic fields over a 1.69:1 bandwidth while the second one can be used regardless of the polarization of the incoming electromagnetic fields over a 8:1 bandwidth. Moreover, the direction finding performances of these vector antennas have been improved in terms of estimation accuracy, sensitivity, robustness to angular ambiguity and polarization mismatch by synthesizing new radiation patterns in the estimation process. A method based on the Cramer-Rao lower bound has been proposed to select efficiently and rapidly the additional radiation pattern