Search results for: Bruno Audone
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Spectrograms are useful diagnotic tools because they allow to improve our understanding of unwanted transient disturbances and in general of the so called sophisticated signals which include frequency-modulated pulses, coded groups, phase-modulated signals, etc. Unlike the limits specified by EMC standards which usually make reference to graphs of amplitude versus time or amplitude versus frequency,...
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Statistical signal processing can be successfully used to detect the immunity degradations of equipment by comparing the results of conducted or radiated immunity tests performed on devices complying with reference standards. A typical example is the verification of the effectiveness degradations of shielding enclosures, where modifications due to aging or introduced for functional reasons affect...
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Extreme Value Theory (EVT) can be adopted successfully to process the data of EMC test results when one wants to determine the maximum electric field generated in the environment where the equipment under test (EUT) is going to be installed. Two methods are illustrated: the peak over threshold (POT) method and the block maxima (BM) method. These methods, which are widel used in financial analysis...
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Conformai mapping is used to investigate conducted immunity tests performed on power supply lines, taking into account the characteristics of the coupling/decoupling networks (CDN) specified by EMC standards. Both test reproducibility and repeatability issues due to their impedance constraints at the equipment under test (EUT) terminals are discussed. Some simulation results are illustrated to show...
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By means of simulation software the substitution and the field strength test methods to measure radiated spurious emissions are investigated to get a better insight into their relevant advantages and disadvantages. The equipment under test (EUT) is a LCX (leaky coaxial cable) antenna driven by a signal generator; this antenna is commonly used in Wi-Fi and Bluetooth applications. The radiation patterns...
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The calibration requirements of radiated immunity tests performed in semi-anechoic chambers and fully anechoic rooms are analyzed by means of electromagnetic computational tools to verify the severity of the allowed tolerance requirements of their anechoic environments. Some proposals of alternative figures of merit directly related to the electric field distribution in the test area or volume are...
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Median filters can be successfully used to eliminate impulsive interference and noise on signal lines overcoming the difficulties of linear filters, which are not suitable to address this problem. Median and median type filters have been popular for the last forty years; they found their main applications in image and speech processing. Unfortunately they are rather unknown to the EMC community. The...
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Conformal mapping is used to investigate the uncertainties of conducted emission tests on power supply lines, taking into account the requirements of test components specified by most EMC standards. Unfortunately, there is no clear common approach in the definition of the coupling devices located between the EUT (equipment under test) and the EMI receiver. Therefore, test reproducibility may be affected...
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In this paper various types of median filters are illustrated to show how efficiently can be used to suppress interference on signal lines. These filters have become popular in digital speech and image processing because they are of easy implementation. After a brief explanation of the standard median filter (SMF) performance characteristics other types of median filters such as the n-th ranked order...
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The EET (Extra Element Theorem) is a useful tool to investigate the impact of mismatch problems at the input and output ports of three port networks such as the Artificial Mains Network (AMN) used in conducted emission tests. The conformal mapping of the input/output transfer function allows to understand the implications of mismatches of the AMN at the EUT port and at the 50 ohm receiver port. The...
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The need of detecting susceptibilities at their onset is a fundamental issue if one wants to perform meaningful immunity tests on equipment and systems. Susceptibilities are often obscured by noise and in many cases it is difficult to discriminate situations of actual malfunction with the minimum risk of making detection errors. This paper tries to give an answer to this problem with a procedure commonly...
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In most cases the results of susceptibility tests based upon pass/fail criteria are purely qualitative; because of this reason it is impossible to define the susceptibility safety margin defined as the difference between the 50% probability of malfunction and the probability of the most critical test conditions. With the help of Logistic Regression one can give a quantitative interpretation also to...
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The phase retrieval problem consisting of estimating the phase of a transfer function from measurement of its magnitude has been around for several years in the EMC community. In the first part of the paper instead of the direct application of the Hilbert integral, two alternative approaches are briefly illustrated: the cepstrum algorithm and the iterative method. They are used in the signal processing...
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One of the most critical problems in immunity testing is to detect the malfunctions of the equipment under test (EUT) when the susceptibility signals are injected into it. In most EMC specifications it is left to the test operator to decide whether the EUT is susceptible on the basis of examination of qualitative output parameters; even if quantitative data is available the pass/fail decision is still...
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The calibration of EMC antenna has always been a frustrating subject for most EMC laboratories. On the other hand in many cases EMC antennas are recalibrated when it is not strictly necessary. This paper proposes a procedure to establish when EMI antennas shall be calibrated on the basis of technical considerations without making reference to abstract quality assurance rules. It seems more correct...
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The need of detecting susceptibilities at their onset is a fundamental issue if one wants to perform meaningful immunity tests on equipment and systems. Susceptibilities are often obscured by noise and in many cases it becomes difficult to discriminate situations of actual malfunction with the minimum risk of making detection errors. This paper tries to give an answer to this problem with a procedure...
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The calibration of EMC antenna has always been a frustrating subject for most EMC laboratories for various reasons. On the other hand in many cases EMC antennas are recalibrated when it is not strictly necessary. This paper proposes a procedure to establish when EMI antennas shall be calibrated on the basis of technical considerations without making reference to abstract quality assurance rules.
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The spectral analysis of random digital signals represents an important issue to understand the EMC performance of equipment and systems. Wold's theorem allows to get a better insight into the spectral structure of the emitted signal. On the basis of the basic principles of this theorem the spectral components of the random digitals are calculated and identified. Using the properties of adaptive filters...
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The present definition of Uniform Field Area (UFA) specified by EN 61000-4-3 does not provide constraints sufficient to guarantee reproducibility. It may be useful to establish a standard adequate for test repeatability when tests are performed in the same test site. On the other hand one is induced to believe that meeting the radiated test uncertainty calculated on the basis of the test equipment...
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IEEE Transactions on Electromagnetic Compatibility > 1980 > EMC-22 > 2 > 130 - 135
Susceptibility testing is generally performed using manual methods which result in the following disadvantages and limitations: tests are time consuming, frequency and amplitude accuracy may not be satisfactory, operator errors can easily occur, and test setup inaccuracies are seldom taken into account and compensated. A new and low-cost method of performing susceptibility testing automatically is...
