The analog to digital front ends of measuring instruments affect crucially the interpretation of the signals acquired from the real world into the digital domain and their back presentation. The signal processing in the digital domain due to its stability meets usually the requirements on the uncertainty of the measuring instruments easily. ADCs and DACs influence dominantly the accuracy of instruments and limit the signal dynamic and their applicability. The exact error description and standardised testing methods are required by the end user. Moreover, the simplification of the error description by dominant error parameters is a permanent task for metrologist and producers. This paper is aimed at providing a metrological overview of ADC and DAC topics by referring to their: i) architectures, ii) modelling and testing, and iii) standardization.

Operation and effectiveness of most electronic systems is strongly affected by their noise rejection capability. The performance they exhibit in the presence of noise is therefore assessed since the early production stage, as well as routinely during periodical maintenance actions. To carry out appropriate tests suitable noise sources are needed. Actually, only white noise sources are widely available on the market; generators capable of producing colored noise are instead very unusual. In theory, ordinary arbitrary waveform generators could be used, once suitably programmed to serve as noise sources. But, test and measurement technicians charged barely find application notes that support them in taking this step. The paper gives relevant remarks concerning the simulation of colored noise, and proposes an analog generator that exploits an arbitrary waveform generator as noise source. The proposed generator is capable of producing noise signals characterized by structured spectral patterns.

The paper deals with the definition of dynamic performance of Analog-to-Information Converters (AICs). These components allow of overcoming the sampling frequency limits of the Shannon's theorem, by assuming that the observed signal has a sparse representation in a given domain. The paper aims to verify the behavior of standard parameters currently defined for Analog-to-Digital Converters when applied to the AICs. To this aim, several simulations and experimental tests have been carried out to study the influence, in the frequency domain, of quantization noise and nonlinearity on the AIC dynamic parameters.

This paper describes the calibration of pH sensor located at the OBSEA marine observatory. This instrument is based on an industrial pH electrode that is connected to a CTD instrument (Conductivity, Temperature, and Depth). The calibration of the pH sensor has been done using a high precision spectrophotometer pH meter from Institute of Marine Sciences (ICM), and in this way it has been obtained a numerical function for the pH sensor proportional to real pH.

The paper deals with measurement and control aspects of active power filtering in ship systems. A main focus of the paper will be concentrated on the analysis of the ways of improvement of compensating current generation algorithms. Two aspects of improvement will be discussed: a choice of an appropriate algorithm and an assessment of the quality of compensation by analysis of resulting waveform distortions on power supply side.