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Page 146 of 977 Results 1451 - 1460 of 9762

Antonio Moschitta, Antonella Comuniello, Alessio De Angelis, F. Santoni, Paolo Carbone
Effect of noise and partial synchronization on amplitude measurement of multiple Chirp Spread Spectrum signals

In this paper, simultaneous amplitude measurement of multiple Chirp Spread Spectrum (CSS) signals is discussed. CSS signals are assumed to be generated by digital devices whose clocks are not fully synchronized. The effects of incomplete synchronization and noise at the receiver side are investigated and discussed, assuming that the signals amplitudes are estimated using correlation techniques.

Gu Yi
Waveform recovery technique based on differential localization algorithm

During the measurement of transmission delay time in Automatic Test System, influenced by the boundary condition, the echo was partially lost, which directly affected the measurement result. By using differential positioning algorithm and implementing a supplementary measurement, the lost echo signal can be recovered,and the result of transmission delay time measurement can be accurately given. Through experiments, this paper proved that the differential positioning algorithm is feasible, and the results are accurate.

Sioma Baltianski
Low Frequency Bias-Induced Impedance

The paper presents the previously unreported properties of current-carrying conductors in the low frequency region utilizing impedance spectroscopy. The studied objects have an additional low frequency impedance during the passage of an electric current. The bias-induced impedance (ZBI) is noticeably manifested in the range of 0.01 - 100 Hz and has either capacitive or inductive nature or both types, depending on the bias level (current density) and material types. The experiments in this work were done using wires made of pure metals, alloys, and non-metal conductors, such as graphite rods. These objects showed the ZBI-effect that distinguishes them from other objects, such as standard resistors of the same rating, in which this phenomenon does not occur. The ZBI-effect was modeled by equivalent circuits. Understanding the nature of this effect can give impetus to the development of a new type of instruments in various fields.

Ding Chao
Study on the magnetic decoupling method of magnetic levitation support for interference spectrometers

Interferometer spectrometer can change the optical path difference of lensby the constant motion of moving mirror, and optical path difference is used for qualitative and quantitative analysis of the function, so keeping uniform velocity and stability in the motion of the moving mirror has a great influence on accuracy and resolution of the spectrometer. In this paper, magnetic levitation device is used as the supporting system of the moving mirror, the motor of the voice coil is the driving system of the moving mirror and we studied the coupling between the two systems of controling the moving mirror. We support a method to analyze the magnetic field in moving mirror system, and decouple the current in the supporting system and driving system. The results show that the control current obtained by this method can effectively control the motion of the moving mirror and keep the moving mirror in a constants peed and stably during the movement.

Luca De Vito, Francesco Picariello, Sergio Rapuano, Ioan Tudosa
Compressive sampling–based vector signal analysis for distributed spectrum monitoring

This paper investigates the application of Compressive Sampling (CS) for the realization of a Vector Signal Analyzer (VSA) node for distributed spectrum monitoring. Herein, the non-uniform sampling approach is proposed for the signal acquisition section of the node, under the assumption of sparsity of the acquired signal in the frequency domain. A simulation analysis has been conducted to assess several figures of merit, characterizing the performance in the frequency and modulation domains. The obtained results demonstrate that the CS could reduce the amount of acquired samples by a factor greater than 10, while still complying with the accuracy required by spectrum monitoring applications.

Valentyn Isaiev, Oleh Velychko
Precise Low-Cost Method for Checking Accuracy of Current Transformers Calibration Unit

The paper presents a method for checking the accuracy of the commercial AC comparators used to calibrate current transformers. This method is simple and convenient and requires no special means of minimizing measurement uncertainty. Only conventional measuring instruments are used making this method cheaper for large amounts of laboratories. The analysis of the currents interrelation of a calibrated transformer and working standard allowed us to derive mathematical models of errors. The obtained models of the ratio error and phase displacement allow simulating different ratios of secondary currents. With the help of the proposed scheme, one can investigate the correctness of comparator readout. The obtained expressions of sensitivity coefficients made it possible to estimate the measurement uncertainty of the simulated reference values. The results of simulating errors from 1 to 1200 ppm for ratio error and phase displacement are presented. Reference values were compared with those obtained using a commercial comparator.

Marjan Urekar, Platon Sovilj, Ivan Gutai, Dragan Pejic, Bojan Vujicic, Djordje Novakovic
Low Power Stochastic Sensor in IoT, IIoT and Industry 4.0 Environments

The low-power stochastic sensor is proposed, and its suitability for operation in Internet of Things and Industrial Internet of Things for Industry 4.0 environments is emphasized. Unlike typical digital sensors, instead of a digitizing module, this sensor has a digital stochastic measurement module that enables low-power yet fast and accurate measurements. Assessment model includes test signal generator, the standard calibrator and the sensor prototype. Multi-channel and large sensor network applications in Industry 4.0 are considered, as well as cost-effective upgrades of the existing sensor networks and adaptability to changing requirements.

Luca De Vito, Francesco Picariello, Ioan Tudosa
A novel measurement method for DAC frequency response characterization

The paper proposes a novel measurement method for frequency response characterization of Digital-to-Analog Converters (DACs). The method uses a Compressive Sampling (CS) technique which exploits the sparsity of the DAC impulse response in the time domain. The mathematical formulation of the method and its preliminary simulation analyses are presented. The obtained results demonstrate that the proposed measurement method based on CS could benefit from a significant sampling rate reduction respect to the Nyquist one.

Karsten Leitis, Tommy Halim
A Novel Recursive Analog to Digital Conversion Method

This paper presents a novel scheme for conversion of analog to digital signals. Applying a native conversion resolution of just one bit with only one comparator the converter is able to increase the resolution as it can be the case with dual slope or ΔΣ converters. The new concept is based on a recursive operation. Therefore the converter is named rADC - recursive ADC. By processing ten recursive cycles a 10 Bit 1 MSa/s test result has been achieved by simulation of a 180 nm CMOS test circuit. The rADC components of the CMOS test circuit are a comparator, a S/H circuit, some gates, transmission gates and two resistors. By the means of a digital control sequence the upper and lower converter reference voltages are redefined in each cycle. As a result the number of cycles or iterations, respectively, determine the resolution of the recursive ADC.

Valentyn Isaiev, Oleh Velychko
Evaluating Uncertainty of Alternating Current Reproduction Using National Standard

The research work was aimed at improvement of metrological service of Ukraine, i.e., to solve a problem of metrological support of the production and operation of the thermoelectric converters, precision meters and sources of alternating current. A method of comparing alternating current with equivalent direct current using the precision thermal converter and shunts was selected to build the standard, and the composition of the standard was established. A functional diagram of the standard was developed to disseminate an alternating current unit. The main sources of measurement uncertainty of this unit are a combination of Type B standard uncertainty of both a thermoelectric converter and a precision shunt. A contribution to combined measurement uncertainty of both the set of measures of electrical resistance and the meters of an output voltage of both a measure of electrical resistance and a thermal converter was analyzed.

Page 146 of 977 Results 1451 - 1460 of 9762