Petar Mostarac

Comparison of RMS Value Measurement Algorithms of Non-coherent Sampled Signals

Comparison of RMS Value Measurement Algorithms of Non-coherent Sampled Signals Uncertainty and bias of RMS measurement of digitally non-coherent sampled signal is dependent on the algorithm used. This paper presents the new Averaging two subsets method for RMS value bias correction of non-coherent sampled signal. Methods for estimating RMS values in the time domain are also compared.

Fall Detection of Patients Using 3-Axis Accelerometer System

Triaxial accelerometers are used as a low cost solution in wide areas of patient care. This paper describes the use of triaxial accelerometer together with ZigBee transceiver to detect fall of patients. The system, including calibration of accelerometers and measurement is explained in detail.

Electrical measurements student laboratory : replacing hands-on with remote and virtual experiments

This paper discusses the problem of transferring knowledge to students of an undergraduate electrical measurement course, and also describes the design of a Web-based measurement laboratory and experimental setup of Web-based experiments at the Faculty of Electrical Engineering and Computing (FER) in Zagreb, Croatia. The suggested design offers the possibility of teaching or presenting high-precision experiments using expensive or sensitive equipment that is unavailable in sufficient quantities to serve large numbers of students.

Precision RMS value measurement of non-coherent sampled signals

Uncertainty and bias of RMS value of digitally non-coherent sampled signal is dependent on algorithm used. This paper presents a new method for RMS value bias correction of non-coherent sampled signal. Methods for estimating RMS values in the time domain are compared.

Novel frequency measurement method with low sampling time

Measurement of time varying frequency is very important in many fields: acoustics, radar signal analysis, seismology, and power quality analysis. In this paper a comparison of several methods for frequency measuring will be performed. The methods were adopted for power quality frequency measuring according to the European standard EN 50160 “Voltage characteristics of electricity supplied by public distribution systems” [1]. The main idea was to measure frequency with as lower as possible sampling time, while trying to observe transients in frequency. The following methods were used for comparison: Interpolated DFT [2], Sine fitting [3], Chirp z-Transform [4] and Hilbert transform [5]. All signals were simulated as thou they are acquired with 16 bit A/D conversion, 50 kS/s, and with range of ± 10 V. The comparison will be in next step repeated on FPGA module with real measurement data.

Use of Triaxial Accelerometers for Posture and Movement Analysis of Patients

Triaxial accelerometers can be used as a low cost solution to wide areas in patient care. This paper describes the measurement system that comprises two triaxial accelerometers together with ZigBee transceivers to measure posture and movement of patients wireless. The system, including calibration of accelerometers and measurement is explained in detail.

Wiener Filtering for Real-Time DSP Compensation of Current Transformers over a Wide Frequency Range

An efficient system for the compensation of current transformers over a wide frequency range is presented. The proposed technique is based on digital signal processing and inverse modeling using the frequency domain approach and Wiener filtering. Since the proposed technique applies finite impulse response filtering, the compensation filter is absolutely stable. The modeling error is reduced using a small time delay in the modeled inverse transfer function, which is unobservable for the human operator. The proposed algorithm is implemented in real time using a PCI eXtensions for Instrumentation system.

Comparison of DMM characterization methods based on RMS noise and standard deviation noise

Analogue to digital converters (ADCs) are very important component of digital multimeters for defining their accuracy. Along with ADCs specifications that are described in this paper, there are also “real” parameters that describe how DMMs and ADCs fare in real world with the presence of noise. Those parameters include, but are not limited to signal-to-noise ratio, effective resolution, effective bits, noise free resolution, etc. The purpose of this paper is to test and compare different DMMs in 6.5–7.5 digit range using the specific formula for effective resolution.

Method for nonlinear fitting and impedance analysis with LCR meter

In this paper new method for nonlinear fitting application is defined, described and tested. The method used the data acquired with LCR meter, nonlinear models of equivalent circuits, nonlinear fitting algorithm and iterative procedure for minimization mean square error between input data and nonlinear impedance model. The low cost LCR meter has been used and adopted to perform frequency range sweep impedance analysis and substitute more expensive impedance analyzer instruments. The method is tested in laboratory with different RLC circuit structures. Presented method for nonlinear fitting and impedance analysis can be applied on data acquired with different instruments according to application needs.

Measurement of resistance ratios with digital voltmeter and DAQ card — A comparison

This paper describes the comparison of the precise digital voltmeters and DAQ cards in measurement of resistance ratios. Recently, 24 bit DAQ cards have emerged as possible measuring instruments that can be used to develop precise measurement methods. They are not as expensive as digital voltmeters, and could replace digital voltmeters in many applications.