Hrvoje Hegeduš

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.

Generic System for Remote Testing and Calibration of Measuring Instruments: Security Architecture

Generic System for Remote Testing and Calibration of Measuring Instruments: Security Architecture Testing and calibration of laboratory instruments and reference standards is a routine activity and is a resource and time consuming process. Since many of the modern instruments include some communication interfaces, it is possible to create a remote calibration system. This approach addresses a wide range of possible applications and permits to drive a number of different devices. On the other hand, remote calibration process involves a number of security issues due to recommendations specified in standard ISO/IEC 17025, since it is not under total control of the calibration laboratory personnel who will sign the calibration certificate. This approach implies that the traceability and integrity of the calibration process directly depends on the collected measurement data. The reliable and secure remote control and monitoring of instruments is a crucial aspect of internet-enabled calibration procedure.

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.

Internet-Enabled Calibration Services: Design of a Secure Calibration System

A growing number of measurements in the commercial and industrial sectors need to refer to traceability to national and international standards. Instrument and reference standard calibration is resource and time consuming. Since many available digital instruments are provided with some communication interfaces and Internet-enabled metrology has rapidly been developing in recent years, it is possible to create an actual remote calibration system with remote control capabilities. This approach addresses a wide range of possible applications that can drive many kinds of different devices and can be easily upgraded. This paper focuses on some of the security problems regarding remotely executed Internet-enabled calibration processes.

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.

A nonlinear least-squares graphical tool ('Gaussfit') for educational purposes

This paper describes a computer program that finds a function which closely approximates experimental data using the least-squares method. The program finds parameters of the function as well as their corresponding uncertainties. It also has a subroutine for graphical presentation of the input data and the function. The program is used for educational purposes at undergraduate level for students who are learning least-squares fitting, how to solve systems of linear equations and about computer calculation errors.

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.

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.