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UN SINTETIZZATORE DUALE A BANDA LARGA PER LA CARATTERIZZAZIONE DI CAMPIONATORI DI PRECISIONE
No full textSISTEMA DI MISURA DI PRECISIONE DELLA TENSIONE ALTERNATA APPLICABILE ALLA DETERMINAZIONE DI GRANDEZZE ELETTRICHE
No full textPolyharmonic Digital Synthesis for the calibration of phase sensitive measuring systems up to the ultrasonic band
No full textA double output digital polyharmonic synthesizer
suitable for the calibration of phase sensitive measuring systems and harmonics in power analyzers is being developed at INRIM.
Digital-to-analog converters with high resolution and update rate simultaneously synthesize a pair of waveforms with fine trimming
of electric parameters and harmonics. Its bandwidth is up to 100 MHz, verified with a wideband sampling oscilloscope, and the
frequency resolution is 20mHz in the whole bandwidth. The synthesizer has been characterized in terms of amplitude, accuracy,
and stability up to 1MHz by means of a programmable ac/dc
transfer standard. For frequencies up to 100 kHz, a calibrated
precision digitizer, configured as a phase comparator, is used
for its characterization. The measured phase offset and noise at
20 kHz are 5 μrad and 300 nrad, respectively. The same digitizer
has been used for the precise measure of the harmonic spurs
up to 100 kHz. Instead, for the evaluation of the total harmonic
distortion from 100 kHz up to 50 MHz, a wideband spectrum
analyzer has been used. The algorithms employed allow the use of
the synthesizer as a digital phase standard or as a polyharmonic arbitrary synthesizer with independent outputs
Quantum sampling AC standard for electrical power metrology based on programmable Josephson junction series array
Full text linkA digitally-assisted current comparator bridge for impedance scaling at audio frequencies
No full textA current comparator impedance bridge, suitable for the comparison of four terminal-pair impedance standards having similar phase angles (e.g., resistors or capacitors) in the audio frequency range at 1:1 and 10:1 nominal ratios is here presented. The bridge is digitally-assisted: its accuracy is granted by an electromagnetic device, a ferromagnetic-core current comparator, but the voltages and currents needed to achieve both principal and auxiliary equilibria are generated by programming a polyphase direct-digital-synthesis generator. The measurement is semi-automated: after an initial setting, the equilibrium can be achieved in a few minutes. Measurements performed on calculable resistors give a base accuracy of a few parts in 10^7 at kHz frequency, with the potential for further improvement
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