1,721,129 research outputs found
Detection of echoes from multilayer structures by using the wavelet transform
No full textA method, based on echo detection by means of the Wavelet Transform, for measuring unknown thicknesses of multilayer structures is presented. Brief theoretical considerations underlying the method are first reported. They highlight the high performance shown by the Wavelet Transform as a powerful analysis tool of echoes in noisy environment. Then, a suitable operative procedure, for the method validation when a standard multilayer structure is not available, is set up and discussed. To this aim tests on (i) simulated signals and (ii) actual signals back from known thicknesses are carried out. Finally, experimental results obtained by the measurement method application to unknown thicknesses referred to the echo-ophthalmic field, are also reported
A measurement method based on time-frequency representations for testing GSM equipment
No full textA digital method for testing and qualification of GSM equipment is here presented. The method, based on the use of time-frequency representations, shows itself suitable to carry out in a whole most of measurements needed for the characterization both of base stations and mobiles. It is so possible to avoid the employment of different instruments, complex procedures, and qualified users. Some aspects regarding GSM measurements are first presented in order to clearly describe the operative stages of the method. Then, its performance is assessed by analyzing reference signals. Experimental results obtained from the application of the method to actual GSM signals are finally given
Dynamic testing and diagnostics of digitizing signal analyzers
No full textThis paper deals with a new dynamic testing method for effective bit number evaluation of digitizing signal analyzers. This technique is valid when, owing to particular working conditions, only a limited number of the sinewave test signal periods can be collected. In such a case, existing test methodologies can present problems for a correct application. The proposed method is based on a regression algorithm and, by virtue of employing the acquisition of a sinewave test signal for a time interval enclosing only three zero crossings of the sinewave, requires a very short computational time. After a brief summary of existing test methodologies, the performances and limits of the-proposed method are analyzed and highlighted. To illustrate the application field of the described methodology, the preliminary simulated results of several devices and the real data relative to one digitizer are reported
PERFORMANCE ASSESSMENT ACCORDING TO IEC 1083-2 STANDARD OF A WAVELET PACKET TRANSFORM BASED METHOD FOR MEASURING THE PARAMETERS OF HIGH VOLTAGE IMPULSES
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