Andrew Henry, Francis Labrique, Christian Eugène
CONTROLLING THE OSCILLATIONS OF A SWINGING BELL BY USING THE DRIVING INDUCTION MOTOR AS A SENSOR

Swinging bells deliver the best sound quality when the swinging angle is kept to a specific value proper to each system. The aim of our paper is to propose an original method for controlling this swinging angle without any external sensor, by using the driving motor (actually a threephase induction machine) as a sensor when it is not active as a motor. In the sensor mode, we control the maximum speed of the bell, which is related to the swinging angle by a timeinvariant mechanical coefficient specific to each bell system. The main advantage of the proposed solution is that the speed information is practically insensitive to the motor parameters variations. This solution, well adapted to the problem of concern, establishes a close interrelation between the motoring, sensoring and regulating aspects. The pertinence of our solution is deduced from theoretical developments and confirmed both by simulations and experimental observations on a real swinging bell system.

Pekko Vehviläinen, Kimmo Hätönen, Pekka Kumpulainen
DATA MINING IN QUALITY ANALYSIS OF DIGITAL MOBILE TELECOMMUNICATIONS NETWORK

Quality analysis of a digital mobile telecommunications network can be a daunting task. For monitoring and operating purposes hundreds of measurements are constantly collected from a complex network. From the measurements the operating personnel of the network should be able to detect the hanges that affect the service quality that the subscriber expects. Data mining methods can be used to ease the operating staff’s task.

Arkadiusz Szewczyk, Ludwik Spiralski, Gérard Ghibaudo, Gilles Reimbold, J. A. Chroboczek
PROGRAMABLE SYSTEM FOR LOW FREQUENCY NOISE MEASUREMENTS IN MICROELECTRONICS DEVICES CONTACTED BY POINT PROBES

A novel system for low frequency noise, LFN, wafer-level (point probe) measurements and a method of the system calibration with the thermal noise of resistances are discussed. We also present some LFN data on MOSFETs as an example of implementing the LFN measurement technique for the device quality diagnostics.

Sergiej Taranow, Andrzej Olencki, Yuri Tesik
THE USE OF TEST SIGNAL FOR MINIMIZATION OF PULSE AND WIDE BAND AMPLIFIERS MULTIPLICATION ERROR

Pulse amplifiers are widely used in radio engineering. The first requirement to these amplifiers is to provide minimal distortion of rectangular pulse shape. The second is provision minimal multiplication error, which is important for measurements. The standard method, grounded on the usage of negative feedback, may be used for wide band periodical signals and unacceptable for amplification pulse signals due to a signal delete in the forward and backward branches. It is proposed to use for this problem solution, borrowed from cybernetic engineering, the adaptive method with small test signal for calibration. The paper illustrates the mechanism of acting, dynamic and static analysis, based on proposed the Method of Linearization by the Describing Functions.

Janusz Smulko, Kazimierz Darowicki, Artur Zieliñski
ELECTROCHEMICAL NOISE ANALYSIS OF UNIFORM CORROSION IN WATER SUPPLY SYSTEM

The results of electrochemical noise measurements and their analysis for evaluation of corrosion intensity in the water supply system are presented. The polarization resistance Rp is calculated for corrosion evaluation, estimated by applying the proposed method of noise analysis. The method includes trend removal and impedance calculation by dividing power spectral densities of the detrended voltage and current fluctuations. The estimated impedance at low frequencies is used for Rp value calculation. The applied algorithm of electrochemical noise detrending is based on its decomposition and after trend removal reconstruction using wavelet transform.