Desenvolupament d'un mètode de mesura de senyals transitòries radiades per avaluar la immunitat de sistemes de comunicació digitals.

L'objectiu d'aquest projecte és desenvolupar un mètode per mesurar senyals transitòries interferents. A més a més, una vegada s'hagi realitzat la mesura s'avaluarà l'efecte d'aquestes senyals sobre sistemes de comunicació digitals amb eines de simulació. Per tant, es determinarà el grau de immunitat que tenen els sistemes de comunicació analitzats quan es veuen interferits pels transitoris prèviament mesurats. L'estudi es centrarà en analitzar sistemes de comunicació en temps real,aquests sistemes són vulnerables al senyal interferent del tipus transitori ja que no és possible realitzar retransmissions de la informació i, per tant, els errors són irrecuperables

Radiated transient interferences in digital communication systems

In the Electromagnetic Compatibility research area, an unsolved interference problem is the measurement and evaluation of the distortion produced by radiated transient disturbances on digital communication systems. This impulsive noise, which is generated by switching devices or by sparks, is a broadband interference that covers the spectrum from DC to several hundreds of megahertz or some gigahertz. Additionally, this man-made noise is characterized by its short and random burst parameters, which make really challenging to measure it correctly. During the thesis, we have explained that impulsive noise is not properly measured and evaluated to prevent interference scenarios, when the EMC standard methodologies are applied. Detectors, such as the quasi-peak, frequency sweep measurements or signal-to-noise limiting evaluation described in the harmonized standards of the electromagnetic compatibility do not enable to determine beforehand the influence of transient interferences. Our strategy to overcome the non-profit measurement has been to perform novel measurement and evaluation techniques beyond EMC standards. The measurement technique developed joins the capabilities of EMI receivers and oscilloscope instrumentations to capture accurately the radiated transient interference. To carry out the measurement, the input stage of the EMI receiver is used for filtering and pre-amplifying purposes, conducting the IF output towards the oscilloscope, which is used for triggering and storage. Furthermore, a final post-processing stage is needed to obtain in time-domain the in-phase and quadrature components of the transient interference. Once the radiated transient interference has been measured properly, an accurate evaluation of the distortion produced to a digital communication system can be estimated. To evaluate the impact of the transient interference, a combination of the time-domain measurement with base-band simulation has been proposed to fulfil the thesis goal. The IQ time-domain measurement enables us to characterize the impulsive-noise present at the communication channel and determine the distortion produced to the digital communication system by means of base-band simulation. The procedure to determine the BER using the base-band simulation has been validated with experimental results, comparing the results reached with the developed methodology with the ones obtained when a communication system device is placed under radiated transient. Excellent results have been obtained employing the developed methodology, considering the interference produced by radiated transient to RFID or GSM communication systems Additionally, a new measurement methodology to obtain the amplitude probability diagram (APD) has been developed, offering the possibility to determine the bit-error-rate including limit lines at the APD diagram. This measurement method, based on captures obtained from a general purpose oscilloscope, makes it possible to obtain the APD measurement at any frequency band with the same accuracy provided by an EMI receiver. Furthermore, the post-processing tools using mathematical software produce the APD results rapidly at any bandwidth, and this makes it more powerful than employing an EMI receiver. The successful APD measurement system created is able to obtain the full-spectrum statistical measurement, employing several time-domain captures which can be acquired in practice immediately. In the final chapter of this thesis, the GSM system is interfered by radiated transients produced by sparks. The results provided by the APD diagram including the limit dots have been especially useful due to its fast capacity to interpret and quantify the degradation produced to the GSM system.En el camp de recerca de la compatibilitat electromagnètica, una de les problemàtiques no resoltes és la mesura i avaluació de les interferències produïdes per transitoris radiats sobre els equips de comunicació digitals. Aquest tipus de soroll impulsiu, que es genera per la commutació d' equips electrònics o guspires, és una interferència de banda ampla que ocupa l' espectre radioelèctric fins a diversos centenars de megahertz o algun gigahertz. A més, aquest soroll es caracteritza per la seva curta durada i l'aleatorietat dels seus paràmetres, i això fa que sigui molt complicat mesurar correctament la interferència. Al llarg de la tesi, hem explicat que el soroll impulsiu no es mesura ni s'avalua adequadament per evitar escenaris d'interferències si s'utilitzen les metodologies definides als estàndards d' EMC. Els detectors, com el de quasi-pic, l'escombratge en freqüència o l'avaluació basada en els límits relacionats amb la relació senyal a soroll no són vàlids per anticipar la influència de les interferències transitòries. La nostra estratègia per solucionar els problemes de les mesures normatives ha estat desenvolupar noves tècniques de mesura i avaluació fora dels estàndards d'EMC. La tècnica de mesura desenvolupada combina les capacitats dels receptors EMI i els oscil·loscopis per capturar la interferència transitòria radiada. Per realitzar les mesures, l'etapa d'entrada del receptor EMI s¿utilitza amb la finalitat de filtrar i preamplificar, enviant la sortida IF cap a l'oscil·loscopi, que es fa servir per detectar i emmagatzemar els transitoris. Per últim, en l'etapa de postprocessament, s'obtenen en el domini del temps els components en fase i en quadratura de la interferència transitòria. Una vegada s'ha mesurat adequadament la interferència radiada, es pot estimar correctament la distorsió produïda sobre els sistemes de comunicació digitals. Per avaluar l'impacte de la interferència transitòria i així complir amb l'objectiu de la tesi, s'ha proposat combinar les mesures en el domini del temps amb la simulació en banda base. La mesura IQ en el domini del temps ens permet caracteritzar el soroll impulsiu present al canal de comunicació i així determinar la distorsió produïda al sistema de comunicació digital mitjançant la simulació en banda base. El procediment per determinar el BER fent servir la simulació en banda base ha estat validat amb resultats experimentals, i s'han comparat els resultats obtinguts utilitzant la metodologia desenvolupada amb els resultats proporcionats directament col·locant un dispositiu sota la influència de transitoris radiats. Els excel¿lents resultats obtinguts considerant interferències produïdes sobre sistemes RFID i GSM han estat publicats. D'altra banda, també s'ha desenvolupat un nou mètode de mesura per adquirir el diagrama de probabilitat d¿amplitud (APD), oferint la possibilitat de determinar la probabilitat d'error en el bit incloent límits en el diagrama APD. Aquest mètode de mesura, basat en captures obtingudes mitjançant un oscil·loscopi de propòsit general, fa possible obtenir la mesura APD en qualsevol banda freqüencial amb la mateixa exactitud que proporciona un receptor EMI. A més, amb les eines de postprocessament desenvolupades és possible produir els resultats APD ràpidament i amb qualsevol amplada de banda, i això fa que sigui un mètode de mesura més potent que no pas utilitzar un receptor EMI. L'exitós sistema de mesura creat per obtenir l'APD és capaç d'obtenir la mesura estadística en tot l'espectre radiolèctric utilitzant poques captures en el domini del temps, les quals a la pràctica soón adquirides de forma inmediata. Al capítol final de la tesi, el sistema GMS és interferit per transistors radiats produïts per guspires. El resultat proporcionat pel diagrama APD, incloent-hi els límits, és especialment útil gràcies a la seva rapidesa per interpretar i quantificar la degradació produïda sobre el sistema GSM

Alternative conducted emission measurements on mains without LISNs

Conducted emission tests are always performed by the use of LISNs in laboratories in accordance with CISPR22, CISPR11 and other similar standards. However, it is not always possible to use LISNs because of some limitations. If the EUT (Equipment Under Test) has large dimensions or high currents, it is not, for most of the time, possible to send it to an EMC laboratory or to use LISNs during the test. As a consequence, usage or development of alternative conducted emission test methods is inevitable in industry. In this paper, we made conducted measurements on actual EUTs in alternative environments whose impedances are different from the standard LISN impedance and continued to establish the fundamentals of alternative conducted emission tests based on the impedance measurements of the EUT, supply and used cables. We also established the correlation, on the basis of impedance measurements, between these alternative conducted emission test method and the reference conducted emission test method.Postprint (author's final draft

Benefits of full time-domain EMI measurements for large fixed installation

It is difficult to properly evaluate the electromagnetic disturbances generated by large fixed installations because of, i.e., the background noise, unsteady emissions and transient interferences. Those challenging EMC issues have been recently studied in European research projects on improved test methods in industrial environments. In order to overcome traditional in-situ EMI measurement troubles, a novel time-domain methodology is proposed and used in a real fixed installation with large machinery. Firstly, a comparison between the developed measurement system, using an oscilloscope, and an EMI receiver is done in some test-cases for validation purposes. After verifying the accuracy of the measurements, we proceed with the measurement campaign applying the full time-domain methodology. The main benefits of employing the time-domain system are emphasised through the results. It was observed that the some remarkable advantages of the time-domain approach are: triggering by disturbance events, extremely reduce the capturing time, identify on real time the worst emissions modes of the EUT, avoid changes at the background noise and perform simultaneous multichannel synchronous measurements.Postprint (published version

On-board compact system for full time-domain electromagnetic interference measuraments

Postprint (published version

A single antenna ambient noise cancellation method for in-situ radiated EMI measurements in the time-domain

This paper presents a single antenna ambient noise cancellation method for in-situ radiated emissions measurements performed using an entirely time-domain approach and the sliding window Empirical Mode Decomposition. The method requires a pair of successive measurements, an initial one for characterizing the ambient noise and a final one for the EMI measurement in the presence of ambient noise. The method assumes the spectral content of the ambient noise is stable between both measurements. The measured time-domain EMI is decomposed into a finite set of intrinsic mode functions. Some modes contain the ambient noise signals while other modes contain the actual components of the EMI. A brute-force search algorithm determines which mode, or combination of modes, maximize the absolute difference between the magnitude of their spectrum and the ambient noise levels for every frequency bin in the measurement bandwidth. Experimental results show the effectiveness of this method for attenuating several ambient noise signals in the 30 MHz – 1 GHz band.Postprint (published version

Improved electromagnetic compatibility standards for the interconnected wireless world

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The future is wireless, a world where everything is interconnected. However, the current standards for ensuring the electromagnetic compatibility (EMC) and the coexistence of such wireless systems urge for a major update. It is shown how novel statistical approaches based on the amplitude probability distribution detector and time-domain measurements are better suited for estimating the degradation caused by electromagnetic interferences on digital communication systems than the established practice of determining compliance according to the quasi-peak detector levels using a pass/fail criterion. Therefore, a redefinition of the test methods and of the compliance requirements in terms of EMC standards must be a priority of the international standardization bodies. Finally, a discussion of the fundamental challenges involved in this standardization breakthrough for EMC is delivered.Postprint (author's final draft

Waveform characterization of calibration-pulse generators for EMI measuring receivers

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents the waveform characterization of calibration pulse generators intended to evaluate the response to pulses of the weighting detectors in CISPR 16-1-1 measuring receivers. First, the standard requirements of the reference pulses are described, and the pulse generators calibration methods based on waveform measurements are briefly discussed. Then, high-resolution time domain measurements are used for characterizing the waveforms of a commercial calibration-pulse generator in terms of rise/fall time, pulse width, mean voltage of the upper state, repetition frequency, and area. Moreover, the results above are used for estimating the spectral density of the impulses, their corresponding quasi-peak level, the pulses bandwidth, and the breakpoint frequencies. Finally, the measurement uncertainty is estimated for CISPR bands A, B, and C/D. Results are in good agreement with other calibrations performed during an intercomparison exercise and the uncertainty satisfy the target ±0.5 dB and 1% given in standards for the impulse area and pulse repetition frequency respectively.Postprint (author's final draft

RFID system evaluation against radiated transient noise

In this paper a radiofrequency identification system according to standard ISO/IEC 14443 type-B is evaluated in presence of transient noise. This real time communication system working at 13.56 MHz is interfered in a controlled environment by different transient bursts varying their level, frequency and duration. The transient burst interference is applied in an AC main wire close to the system and the effect over the digital communication system is evaluated using two different methods. The first one is observing directly an RFID equipment in presence of transient signals, and the second one is capturing the interference in time domain an evaluating its effect by means of simulation. The RFID system is affected by these transient noises causing different types of errors. It is shown that it is essential to measure and evaluate in time domain the transient phenomena to ensure that the RFID system do not have susceptibility problems.Peer ReviewedPostprint (published version

Waveform Approach for Assessing Conformity of CISPR 16-1-1 Measuring Receivers

An alternative approach for assessing the conformity of electromagnetic interference measuring receivers with respect to the baseline CISPR 16-1-1 requirements is proposed. The method’s core is based on the generation of digitally synthesized complex waveforms comprising multisine excitation signals and modulated pulses. The superposition of multiple narrowband reference signals populating the standard frequency bands allows for a single-stage evaluation of the receiver’s voltage accuracy and frequency selectivity. Moreover, characterizing the response of the weighting detectors using modulated pulses is more repeatable and less restrictive than the conventional approach. This methodology significantly reduces the amount of time required to complete the verification of the receiver’s baseline magnitudes, because time-domain measurements enable a broadband assessment while the typical calibration methodology follows the time-consuming narrow band frequency sweep scheme. Since the reference signals are generated using arbitrary waveform generators, they can be easily reproduced from a standard numerical vector. For different test receivers, the results of such assessment are presented in the 9 kHz–1 GHz frequency range. Finally, a discussion on the measurement uncertainty of this methodology for assessing measuring receivers is given.Postprint (author's final draft