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An approach for time and frequency measurements based on the use of data acquisition systems equipped with elementary processing capabilities is proposed. The bases of the proposal and its features that, in principle, allow measurements characterized by very fine resolution, are illustrated theoretically; preliminary results are finally given.

An arbitrary waveform generator architecture that exploits multiple DAC cores to increase the sample rate with respect to AWG architectures based on an individual DAC is proposed. The processing operations necessary to distribute the waveform samples between the DAC cores are illustrated. The preliminary results highlighting the performance expected from the proposed architecture are shown.

The scope of the present work is to illustrate the main idea and the realization process at the basis of Flying Outfit for Control of Unsafe Seagulls FOCUS project. The project has been realized by a consortium of companies in collaboration with the University of Naples "Federico II" and CeSMA (Centro Servizi Metrologici e Tecnologici Avanzati) center. The main objective of the research is the definition of a process able to provide a supply of services for the management of coexistence problems between human and unsafe seagulls by means of small remotely piloted aircraft. The main purpose is to overheat the seagull eggs in the nest by means of a microwave device so they are no longer fertile. This is considered as an acceptable way to reduce the risk of unsafe interaction among seagulls and humans. The paper describes the different steps needed for the realization of the mission and the small unmanned aircraft used for the monitoring, operating on the nest, and collecting of gull fecal samples. Finally, the software developed for image detection of seagulls nest is presented.

The paper introduces the conceptual framework of a Distributed Sensor Network for the monitoring of the wooded areas under risk of fire in the so-called “Vesuvius’ red zone”. Main goal is the determination of the OPtimal Evacuation Route for Animals (OPERA) in case of fire, for all the animal species living in the Mount Vesuvius’ surrounding areas, under the perspective of the Disaster Risk Management principles.

In this paper, a classification method for the identification of the characteristic parameters of an unknown Longe Range (LoRa) signal is proposed. In order to reduce the effective sampling rate, the Compressive Sampling, a new acquisition paradigm that promises of exceeding the Nyquist-Shannon theorem, is used. In particular, values of sampling rate lower than 1Msamples/s have been experienced thanks to a proper random sampling strategy and the exploitation of discrete cosine transform (DCT) to achieve a sparse representation of a LoRa signal. Method performance are assessed by means of MATLAB simulations, using LoRa signals acquired with a proper experimental setup. Normal distributed noise vectors were added to each signal in MATLAB for a broad range of signal-to-noise ratio (SNR) values. As result, the obtained percentage of correct classification for each SNR value assures the reliability of the proposed approach in most operating conditions.

A laboratory conceived as a service provider that allows remote clients using sets of instruments, regarded as ‘things of the internet’, is proposed. To assure efficiency and responsiveness, the laboratory controller is programmed as a multithreading system, which can take advantage of multicore processors, now available at accessible costs. The laboratory server relies on TCP /IP communication with clients, and uses GPIB bus to control local instruments. It allows several clients to connect and interact with the specific resources of the laboratory. Thanks to the availability of identical sets of resources, and to the underneath multithreading philosophy, clients requests are processed in parallel rather than according to a classical queuing approach.

Data transfer rates for aggregated video data stream and within data centers nowadays require an electrical bandwidth up to 100 GHz. This poses big challenges for the design of proper test and measurement solutions, notably related to the acquisition of signals with such a wide bandwidth. To grant sufficient bandwidth and related sample rate, modern oscilloscopes have been using techniques based on frequency-interleaving and time-interleaving, respectively. Earlier this year, an alternative technique has been presented in a white paper [1],[2] based on which an oscilloscope that can offer an electrical bandwidth that is two times that of the adopted ADC has been launched. This result is obtained by combining the operations of a couple of time interleaved channels, each one made up of a mixer followed by an ADC. The paper presents a synchronous time interleaving technique, which can be regarded as an extension of the aforementioned technique. In fact, the proposed technique can be implemented through an architecture that includes four channels, each one including a mixer and an ADC, the latter having an input bandwidth equal to just one fourth the electrical bandwidth achieved by the system.

Anywhere a primary electrical source is not available, batteries seem to be the only way to allow the use of stand-alone electrical facilities. Unfortunately, there are some issues related to the use of batteries such as the necessity of regularly checking their charge status and, eventually, proceeding to their replacement, as well as of caring for their treatment as special waste at the end of their lifecycle that have to be faced; actually the delayed replacement of exhausts batteries is the primary cause of unavailability of the services offered by stand-alone devices. Rechargeable batteries just mitigate the aforementioned issues, since they require periodical interventions likewise to perform recharging, that, nonetheless, can be as troublesome as their replacement in several situations. Wireless power transmission approaches smoothly fit batteries recharging applications. In particular, by means of suitable solutions it is possible to recharge batteries without invasive operations, such as removal and reinstallations, but letting the batteries on board of the supplied device. In this paper, a wireless power supply system suitable to recharge general purpose NiMH batteries and Li-ion mobile phones cells, as well as the auxiliary wireless sensor systems, is presented. Details related to an experimental set-up aimed at highlighting the feasibility of the proposed approach are plenty given.

Wireless sensor networks are today more and more widespread. Along with the installation of more and more networks, a number of new standard documents has also been produced to update the regulation concerning data communication between sensors and data collectors. Differently, less attention has been paid to the different modes of powering the local sensors. At present, the energy required for local sensors functioning is essentially battery provided, despite the battery supply is often recognized as a critical aspect of remote sensing. In fact, the periodical battery replacement is sometimes non-strategic and troublesome, especially for those sensors which have to be installed in difficult to reach sites, or are integrated into medical implantable devices. In the abovementioned circumstances, battery-less sensors appear to be attractive, both from a pragmatic point of view, because of the strategic role they can play in critical scenarios, and from an innovation-oriented point of view, because of the novelty that wireless power transmission can add to a new groundbreaking remote sensors technology. Wireless power transmission technologies are capable of supporting battery-less sensor functioning. In this paper, first the main issues related to alternative remote devices powering solutions are plainly discussed, then, a resonant-based induction power transmission system for supplying a sensor network is also presented.

Noise sources are needed for test and validation of noise sensitive electronic systems but only wide band white noise sources are directly available on the market. In this paper a programmable colored noise generator is proposed. The system allows to configure the spectral features of the noise and is implemented with a Field Programmable Gate Array that produces the digital samples of the noise and a Digital to Analog Converter that produces the analogue output. The proposed generator overcomes the state of the art in terms of bandwidth and flexibility and produces a noise sequence whose length is unlimited for practical purposes. Experimental results show that the bandwidth of the generated noise can be selected up to a maximum of 120 MHz while defining the power spectral density with a frequency resolution equal to 0.2 % of the selected bandwidth.

Contactless induction mechanisms represent a valuable solution to recharge battery-powered vehicles when plugging to the mains reveals troublesome or impossible. A relevant example is that of unmanned aerial vehicles (UAV) employed in hostile environments for persistent surveillance and perils reconnaissance. To complete long duration missions, these vehicles have to land on mobile platforms several times to recharge. Specifically, the vehicle has to land on the platform, which is covered by a landing pad with copper contacts, precisely positioning on the contacts otherwise fails to recharge. Also, the recharging platform can be neutralized by dust deposited on the landing pad and corrosion due to chemical causes. A contactless power transfer system that relies on induction mechanisms and permits to improve the reliability of the recharging platform is presented. The ground electronics and the on-board front-end utilized to capture the induction flow and convert the associated power to recharge the batteries are described in detail.

The main issues concerning the development of induction and wireless power transmission technologies aimed at supplying and/or controlling remote electrical equipment are discussed. The attention is mainly paid to critical logistic scenarios and measurement applications. Typical critical logistic scenarios consist in situations in which battery-less instrumentation needs to operate in wastelands or desert zones where connections to the grid are unreliable or missing, or in blocks or buildings where the main grid has been intentionally shut down. Induction and wireless power transmission technologies share large part of the aforementioned field of application. The paper shows the state-of-art of the two technologies and highlights both differences and similarities as well as weak-points and advantages of both of them. Future pilot experiments aimed at enforcing the two technologies are envisaged.

The NeVoCGPS network consists of 30 GPS stations that implement a geodetic surveillance system of the volcanic area surrounding the city of Naples, in the south of Italy. Being deployed over a densely urbanized area, the GPS network is subject to many sources of potential interference, which can make some station unavailable. On the basis of a new experimental campaign and of the analysis of past recorded data, the authors have recently proposed the use of SNR, which is by default calculated by receivers, as a key parameter for the diagnostic of the state of health of GPS stations. The paper presents an efficient online system for monitoring the state of health of GPS stations. The goal of the system is to continuously provide the operators with information on the quality and the trustworthiness of the data gathered by the GPS stations, trigger proper maintenance actions, before an eventual problem arises, and ultimately reduce the unavailability of the stations.

The paper presents an experimental study of the effects of in-channel interference on the performance of a CGPS receiver, which is a node of a large geodetic surveillance system in the Neapolitan volcanic area, in the South of Italy. A suitable reconfigurable experimental setup has been developed, to emit controlled interfering signals chosen on the basis of previous studies and at the same time to evaluate the performance of the GPS receiver. The analysis of the experimental data can help to accomplish two goals: the prediction of the performance of GPS geodetic monitoring systems on the basis of SNR measurements, and the selection of the positions of new continuous GPS stations that are to be put in service to enhance the existing systems.

In order to assess the performance of digital to analog converters (DAC) the attention is generally focused on the integral nonlinearity (INL). Useful diagnostic tools to detect the causes of poor linearity are the linearity and intermodulation errors, which can be evaluated from INL measurements. Linearity and intermodulation errors highlight and quantify erroneous calibration and unwanted interactions between current sources inside the DAC hardware. Unfortunately, their estimates, especially those related to high order intermodulation errors are characterized by high uncertainty. It is thus difficult assessing their relevance on the base of their very uncertain value. It is shown that by means of the analysis of variance (ANOVA) the relevance of intermodulation errors can be assessed from a limited set of INL measurements. ANOVA is in fact capable of distinguishing if the variance in INL measurements has to be addressed to active factors or noise, even if the effect of each factor is widespread upon different elements of the INL array and in different combinations with the other factors.

Performance assessment, based on design of experiments, of a measurement method capable of measuring the typical parameters of wideband signals in the presence of interference is dealt with. Due to the several operating conditions, in terms of signals typology and power level or noise power level, in which the proposed method can be utilized, a complete and fully-comprehensive experimental assessment would entail a longest and unfeasible experimental phase. Thanks to the design of experiment and the development of a suitable experimental plan, it is possible to notably reduce the number of conducted experimental tests and obtaining as much information as possible on the effects of each factor on the performance of the proposed method. In particular, the use of a standard fractional factorial plan, usually referred to as Resolution III, along with a proper data statistic analysis, based on analysis of mean and variance, is suggested. The bias 8 and standard deviation a of measured parameters, such as channel bandwidth and power and carrier frequency, are evaluated as performance indicators.

A novel built-in solution for improving the effective number of bits of data acquisition systems (DASs) in presence of band-pass input signals is presented. The proposed solution takes advantage of the processing capabilities of modern DASs. It allows acquiring a seamless data stream with improved resolution, and imposes very little hardware requirements.

In the paper the problems that arise in the experimental evaluation of DACs dynamic parameters are discussed. Usually, a measurement station for DAC characterization provides the time evolution of the DAC output voltage. A fundamental issue deals, then, with the synchronization between the acquired voltages and the codes sequence at DAC input, in order to shape the DAC characteristic, which associates the output voltage to each input code. Therefore, a timing association procedure, able to furnish the transfer function of the DAC under test during the characterization stage is required.

DACs are frequently utilized to generate non-standard waveforms. In particular any DACs approximate the desired waveform with a piece-constant one, produced by stepping up or down the output voltage of some amount at regular time intervals. The effect of the voltage steps characterizing piece-constant waveforms have been barely investigated in the past years. The paper presents a descriptive model for DACs that takes into account the piece-constant nature of the output waveform as well as non-idealities, such as time-base instability and non-linearity errors. The model describes well the behaviour of real DACs and permits to estimate the spectral features of the generated waveform, avoiding some pitfalls the simulation can be responsible for.

A ground monitoring system that exploits electromagnetic field properties of accounting of both physical and geometrical features of the surrounding medium is proposed. The system is based on TDR tests, assisted by a control and processing unit, and aims at detecting starting cavities underground in the soil. The digital signal processing approach deployed for waveform analysis, which plays a fundamental role in detecting and characterizing underground anomalies, is described.

Assessing the dynamic performance of digital-to-analog converters (DAC) is challenging due to the limited resolution of flash analog-to-digital converters (ADC) that are used for the scope. Current solutions are either difficult to be implemented in practice or suffer from serious limitations due to the uncertainty of the hardware utilized. The paper present an innovative method for testing the dynamic performance of a DAC that uses a low resolution ADC just as the other solutions, but exploits it to digitize an amplified version of the error signal, instead of the DAC output signal. The limitations due to the hardware are thus overcome. The results of a number of simulations confirm the feasibility of the proposed method.

Measurement of phase noise affecting oscillators or clocks is a fundamental practice whenever the need of a reliable time-base is of primary concern. In spite of the number of methods or techniques either available in literature or implemented as personalities in general purpose equipment, very accurate measurement results can be gained only from expensive, dedicated instruments. To offer a cost-effective alternative to dedicated instruments, the authors have already realized a DSP-based phase noise meter, capable of assuring high performance and real-time operation. The meter, however, suffers from a reduced analysis bandwidth (about 250 kHz) and needs an external time-base for input signal digitization. To overcome these drawbacks, the authors propose hereinafter the adoption both of bandpass sampling strategies and internal time-base. After some remarks on the previous version of the meter, key features of the adopted time-base and proposed sampling strategy are described in detail. Results of experimental tests, carried out on sinusoidal signals provided both by function and arbitrary waveform generators, are presented and discussed; evidence of the meter's reliability and efficacy is finally given.

The paper is focused on monitoring operations performed in power systems. The attention is paid to slow variations characterizing frequency and amplitude parameters of sinusoidal components. A suitable digital signal processing method aimed at estimating frequency and amplitude variations characterizing both the fundamental component as well as single harmonics and interharmonics contained in distorted waveforms is presented. To track time-varying frequency the method first detects the phase deviations of the sinusoidal input with respect to the expected linear trend, and then evaluates the time derivative. In parallel, to track amplitude fluctuations the method takes the square root of the quadratic summation of input sinusoidal projections on two orthogonal references. Distributed filtering operations grant the capability of distinguishing and separately analyzing close-to-each-other components; phase unwrapping allows components affected by significant frequency variations to be tracked.

Modeling of digital-to-analogue converters (DAC's) and identification of their chief parameters is here dealt with. The attention is focused on a well-known static model accounting for linearity and intermodulation errors, which are of major concern for DAC functional characterization as well as troubleshooting. Estimation of model's parameters is currently carried out through linear transformations, the application of which is not practical for high resolution DAC's; also, usable relations for assessing the uncertainty on estimated parameters are not given. The authors introduce a new parameter in the model with the aim of proposing an alternative formulation. Complete identification of the DAC under test can thus be pursued through a new fast transformation, characterized by reduced computational burden and suitable for fully in-place implementation

A new digital signal processing method for instantaneous frequency estimation is proposed here. The attention is mainly paid to signals whose instantaneous frequency trajectories exhibit a periodic evolution versus time. Thanks to an optimized use of the warblet transform, the method assures superior accuracy and resolving capability with respect to other solutions already available in the literature, thus showing itself very attractive in the presence of multicomponent signals characterized by instantaneous frequency trajectories extremely similar and very close to one another. Theoretical notes regarding the warblet transform and its optimized use in the framework of the proposed method are first given. Then, the fundamental steps of the method are described in detail with references to a clarifying example. The results of a number of experiments on emulated and actual signals, aimed at assessing the performance of the method, are finally presented.

The modem power converters adopted for adjustable speed drive applications are based on switching devices, such as IGBTs, characterised by very fast commutations and high switching frequencies. With such low switching times (fractions of /spl mu/s), problems have become apparent on the long-term behaviour of the motor insulation. Indeed, the inverter output voltage is not pure sinusoidal but it presents sharp pulses in correspondence with the power devices commutations and it is characterised by a considerable harmonic content. Due to supplementary stresses caused by commutations and to space charge formation inside the insulation, the dielectric strength of the materials decreases as a result of the more intense partial discharge (PD) activity and the life expectancy of the machine is sensibly reduced. Since little is known on the PD behaviour of the insulating material under such distorted voltages, an experimental activity has been carried out by performing Ultra-Wide Band detection of partial discharges on specimen subjected to typical inverter output voltages. The analysis of the detected signals has been carried out by means of a suitable digital signal processing approach, based on the Wavelet Transform, capable of extracting the PD pulses occurring during the overvoltages caused by the commutations of semiconducting devices.

A measurement method for instantaneous frequency estimation is presented in the paper. The method is based on the use of the chirplet transform, a linear time-frequency representation (TFR) allowing additional modifications of each cell on the time-frequency plane with respect to other TFRs. In particular, a modified version of this transform is here proposed; a bending effect can further be imposed on the cells. Thanks both to this feature and a suitable measurement procedure, properly set up by the authors, the method grants both a satisfactory accuracy in reconstructing the instantaneous frequency trajectory of monocomponent signals and an good resolving capability in the analysis of multicomponent signals whose instantaneous frequency trajectories are strongly nonlinear and very close to one another. Details concerning the theory underlying the chirplet transform and the proposed modified version are first given. Then, the measurement procedure for optimizing the values of the parameters of the transform according to the local features of the analyzed signal is described in detail. Finally, the results of several experimental tests conducted both on monocomponent and multicomponent signals are presented; advantages over other solutions are also highlighted.

An analytical model to evaluate the hybrid architecture of a wide bandwidth high-speed digitizer is proposed. The model is based on the robust approach of multi-rate signal processing theory and allows analyzing the effects of the impairments that can affect the digitizer, and consequently evaluating achievable performance. The proposed model can also be used at design stage to identify viable solutions for counteracting the effects of the impairments. More specifically, it can be used to identify the correction filters that provide a digital representation of the input signal that minimizes spurious terms and distortions.