Claudio Narduzzi

Digital time-of-flight measurement for ultrasonic sensors

Ultrasonic sensor measurements are mostly based on the determination of the time of flight (TOF). The authors present the development of a digital algorithm for pulse-echo measurement applications, based on the use of a cross-correlation function to determine the TOF. Some experimental results are presented, and the possibility of realizing a low-cost real-time measurement system is considered. >

A/D converter performance analysis by a frequency-domain approach

An analysis of the frequency domain approach in the test of analog-to-digital convertors (ADCs) is presented. Following the introduction of a spectral analysis algorithm based on the use of windows with minimum sidelobe energy, expressions are given to determine ADC performance parameters. Corrections are introduced to improve accuracy in practical cases, and simulation results are presented to support the discussion. The approach presented is sufficiently precise in the characterization of a device, even with data records of comparatively small size. Provided the appropriate correction factors are taken into account in some determinations, the accuracy is not dissimilar to that of other test methods, with the advantage that both data acquisition and data processing procedures are fairly simple.<<ETX>>

Performance analysis of Kalman filter-based clock synchronization in IEEE 1588 networks

This paper analyzes the effects on synchronization performances of the accuracy of skew and offset estimates, the short and long-term stability of the unregulated clock, the rate at which timing information is exchanged within the network. The work makes use of a simulated clock based on the state-variable model, for which realistic parameters are obtained from experimental measurements of Allan variance plots for different kinds of clocks.

Dither signal effects on the resolution of nonlinear quantizers

The consequences of dithering on nonlinear quantizers are analyzed. A model of the nonlinear quantizer is considered, and a model of the same quantizer with dither is proposed. The proposed model permits the description of both monotonic and nonmonotonic nonlinear quantizer characteristics. By means of this approach, relationships are given for the total quantization error in the case of discrete binary, uniform, and Gaussian dither signals. >

Investigating WirelessHART coexistence issues through a specifically designed simulator

In this paper, the WirelessHART communication scheme is investigated. The protocol is at first described, in order to underline the key aspects of its design; then, a simulation tool is presented: it enables analysis that accounts for both protocol and physical layers issues. In particular, interference effects on protocol choices can be easily analyzed. The experimental results, obtained from simulations, highlight improvements of WirelessHART with respect to IEEE 802.15.4 standard, concerning the Packet Error Ratio (PER) degradation of interfering networks.

Accuracy of effective bits estimation methods

The basic assumptions of analog-to-digital converter (ADC) effective bit estimation procedures are analyzed and closed-form expressions that link accuracy to the parameters that describe the measurement conditions are derived. It is shown that the achievable accuracy mainly depends on the ratio between the number of acquired samples and the number of ADC quantization levels. Furthermore, the effect of broad-band noise superimposed to the sinewave employed as test input is analyzed. Results useful for the design of the estimation procedure itself are also provided.

Detection of Anomalous Behaviors in Networks from Traffic Measurements

Analysis and monitoring of traffic measurements can provide a useful tool for diagnostics, troubleshooting, and performance analysis in networks. This paper presents a method for traffic analysis based on the theory of extreme values. Numerical time series obtained from traffic measurements are processed to compute statistical indicators and analyze them to detect significant local features, which may point to some critical network behavior.

Resolution Enhancement by Compressive Sensing in Power Quality and Phasor Measurement

Measurement in power systems and, particularly, in smart grids and smart microgrids is often concerned with harmonic analysis of voltage and current waveforms. The use of Fourier-based algorithms is widespread, and the limits following from the fundamental time-versus-frequency tradeoff that relates observation time to frequency resolution are well understood. This paper presents the application of an algorithm based on the principles of compressive sensing that can achieve an order-of-magnitude resolution improvement without significantly extending total observation time. For harmonic analysis in power systems, this means that accurate results can be obtained using shorter observation intervals, which allow to effectively track changes and reduce the effect of transients on measurements. The application of the algorithm to harmonics and interharmonics, as well as to phasor measurement, is considered and analyzed.

A noise model for digitized data

The paper analyzes the overall conversion error of a noisy digitizer affected by Gaussian noise at its input or generated within the digitizer itself. It is shown that, under mild conditions concerning the ratio between the input noise standard deviation and the quantization step, the overall conversion error can be modeled by a Gaussian random variable uncorrelated with the input sequence. The power of the global conversion error is evaluated in closed formulae together with its degree of variability. Numerical simulations support the proposed analysis.

Modeling and Simulation Analysis of PTP Clock Servo

In the paper we present a behavioral simulation of PTP synchronization, based on the OMNeT++ simulator. Node, link and traffic source behavior are represented by statistical source and flow models. This approach, which differs from most approaches to PTP analysis, allows to focus on fundamental aspects of analysis and can be useful to assess the suitability of PTP synchronization in relation to network architecture and operating conditions, as well as for the optimization of clock servo design.