9762 papers found
The growth of the Internet and its impact on other communication technologies is nothing new today. One of the issues is the migration of voice traffic from Public Switched Telephone Network (PSTN) to packet networks. In this paper we will show the impact of that migration on the occurrence of echo, and the use of solutions that are implemented in the VoIP network.
The incoming technologies allowing for a massive use of remote driven instruments could improve the quality of the experiments in laboratory sessions, especially for what concerns the very specific high level classes. Moreover, taking into account the large number of students, the availability of the lab can be greatly extended. In order to give flexibility and high performances to the educational tool a user friendly virtual instrument has been realised allowing distance learning. Some basic experiments can be performed by the user, namely the analysis of both the RC and the RLC circuits,...
The paper describes an algorithm for fast and precise tracking of sinusoidal signals. The implementation is designed for a system where the acquisition and processing of the input signal samples are performed in real time. Few instructions are required at every step, so the algorithm can be applied to signals having a relative high frequency.
Instrument transformer accuracy testing by the method based on integration of DFT and virtual instrument concept, composed of standard hardware (osciloscope, PC) and specific software is outlined. The structure of the realized virtual instrument for accuracy test of current transformer by DFT method is shown. The method has experimentally verified and compared with measurements made with the classical complex Hohle compensator.
This paper describes architecture a new pure digital frequency synthesizer based on generators, counters and a register. The technique described here is much simpler then other method. Presented synthesizer is the most suitable for the design of VLSI architectures or for programmable Large Scale Integration. On the other hand, this synthesizer has a disadvantage in low output frequency, but this can be overcome by using this synthesizer together with phase locked lop.
The goal of this paper is to provide analysis of Universal Serial Bus, multipurpose communication interface, in application to laboratory measurement systems. This interface is compared with others, established measurement interface standards, especially IEEE-488, in a view of requirements in this specific application. The current market offer and trends in software and hardware design are reviewed. Obstacles to common use of USB in measurements are pointed out and projections to the future use are made.
This paper presents the results of vibration measurement during several specific tests of 35 MVA hydro-generator.
Object based universal software system for ADC testing which enables an easy programmer’s access and expansion (update) is introduced in this paper. The basic idea of the object oriented design and some aspects of the software solution of the ADC testing are described.
Time-scheduled oil changes in internalcombustion engines are often performed well before the oil starts to significantly lose its lubricating properties. A check of oil properties using laboratory analysis methods is expensive. Using the same techniques during service would be extremely difficult. Consequently, oil is seldom analyzed before substitution, which results in oil wasting. This paper shows that in the low frequency range, the temperature coefficient of the dielectric constant of lubricating oils depends on whether the oil is fresh or it has been used. Hence, the change in...
In conventional applications of the remote field eddy current technique, a probe with low frequency sinusoidal excitation is used for measurement of ferromagnetic tube wall thickness. An additional probe with high frequency excitation is required for measurement of the tube inner diameter (electrical caliper). In this paper, this is illustrated with results of finite element analysis. However, the waveform of the pulse driving current and shorter probe length potentially allow the measurement of the inner diameter and the wall thickness with the same probe. We present results of our...