Antonio Cataliotti, Valentina Cosentino, Dario Di Cara, Alessandro Lipari, Salvatore Nuccio, Ciro Spataro
UNCERTAINTY EVALUATION IN POWER MEASUREMENTS WITH COMMERCIAL DATA ACQUISITION BOARDS

The paper deals with the metrological characterization of a digital wattmeter developed by using a personal computer, a shunt, two commercial data acquisition boards and commercial software. The uncertainty of the active power measurements is assessed individually characterizing the voltage channel, the current channel and the phase displacement measurement between the two channels. In particular, the uncertainty on the voltage and current rms measurements is evaluated by using an already proposed approach based on the Monte Carlo method and on the usage of five parameters, while the uncertainty on the phase angle is experimentally estimated. In order to validate the proposed approach for the uncertainty evaluation, various experiments were carried out and a comparison with the Italian National Standard wattmeter was made. The results show that the proposed PC-based solution can be suitable for the development of standard instrumentation, since its accuracy is comparable to the accuracy of much more expensive and sophisticated instrumentation.

Anna Szlachta, Robert Hanus, Adam Kowalczyk
VIRTUAL INSTRUMENT FOR THE ESTIMATION OF THE TIME DELAY USING CONDITIONAL AVERAGING OF RANDOM SIGNALS

The paper presents a virtual instrument (VI) which allows to carry out the simulation and experimental studies of the various statistical methods of random signal time delay measurement including the methods developed by the authors which employ the conditional averaging of signals. The VI includes generators and oscilloscope and also a PC with the DAQ card and the software developed in the LabVIEW environment. The instrument allows to model and generate the stochastic signals with definite statistical parameters, to acquire signals from external sources, and to perform the time delay estimation with the use of several methods. This study describes the principle and properties of the method which employs the conditional average value of the absolute value of delayed signal (CAAV), and some exemplary results of this method with the use of the built instrument are presented. The results obtained with the CAAV method have been compared with the results obtained by the best known and used at the measurements of random signal time delay method of cross correlation (CCF). It has been found that the CAAV method is featured with lower time delay variance than the CCF within the signal-to-noise ratio higher than 0.35.

E. Balestrieri, M. Catelani, L. Ciani, S. Rapuano, A. Zanobini
EFFICIENT ESTIMATION OF THE WORD ERROR RATE OF DIGITIZING WAVEFORM RECORDERS

The paper proposes a new method for Word Error Rate (WER) measurement for digitizing waveform recorders. In particular, a WER estimation procedure, based on Student’s t distribution, is provided to estimate the WER and its confidence interval, minimizing the acquisition record length. The proposed test procedure has been experimentally verified by means of WER measurements on actual digitizing waveform recorders, where the test results have been compared to those achieved by implementing the method described in the IEEE Std.1057. Two measurement set-ups have been adopted in order to prove the validity of the proposed approach.

David Stoppa, Fausto Borghetti, Justin Richardson, Richard Walker, Robert K. Henderson, Marek Gersbach, Edoardo Charbon
ULTRA COMPACT AND LOW-POWER TDC AND TAC ARCHITECTURES FOR HIGHLY-PARALLEL IMPLEMENTATION IN TIME-RESOLVED IMAGE SENSORS

We report on the design and characterization of three different architectures, namely two Time-to- Digital Converters (TDCs) and a Time-to-Amplitude Converter (TAC) with embedded analog-to-digital conversion, implemented in a 130-nm CMOS imaging technology. The proposed circuit solutions are conceived for implementation at pixel-level, in image sensors exploiting Single-Photon Avalanche Diodes as photodetectors. The fabricated 32 × 32 TDCs/TACs arrays have a pitch of 50 µm in both directions while the average power consumption is between 28 mW and 300 mW depending on the architectural choice. The TAC achieves a time resolution of 160 ps on a 20-ns time range with a differential and integral non-linearity (DNL, INL) of 0.7 LSB and 1.9 LSB respectively. The two TDCs have a 10-bit resolution with a minimum time resolution between 50 ps and 119 ps and a worst-case accuracy of ±0.5 LSB DNL and 2.4 LSB INL. An overview of the performance is given together with the analysis of the pros and cons for each architecture.

Marco Ricci, Luca Senni, Pietro Burrascano
VIRTUAL INSTRUMENT FOR AIR-COUPLED ULTRASOUND NDT APPLICATION BASED ON PSUEDO-NOISE SEQUENCES

A Virtual-Instrument for Air-Coupled Ultrasound Non Destructive Testing applications based on Psuedo- Noise Sequences is presented. The instrument is designed by means of the LabView software to manage and synchronise a digital input/output module and a virtual oscilloscope and to implement the digital processing required to fully exploit the characteristics of the coded excitation. The Signal to Noise Ratio enhancement assured by this technique with respect both Additive White Gaussian Noise and Quantization Noise is theoretically analysed and experimental verified.