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.

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.

Assignment of the inductance Q-factor is given by the determination of equivalent circuit parameters of the measured inductor or the Q-standard. In case of serial equivalent circuit, values of the inductance LS and the resistance RS have to be evaluated. Conventional precious bridges routine used for inductance and resistance measurements typically work up to some hundreds of kHz. For higher frequency ranges these methods are not available to apply for finding both parameters inductance LS and resistance RS.
This paper describes a method based on utilizing resonance technique for inductance Q-factor measurement. The measured inductor and auxiliary capacitor form the resonance circuit. Impedance of this circuit is measured by means of an impedance analyser in suitable wide frequency range around the desired frequency. Subsequently mathematical data processing is applied to improve results obtained from the impedance analyser. This method has been developed for calibration of Q-standards designed for ultra-acoustic frequency range (typically hundreds of kHz up to tens of MHz).

The paper compares six methods of measurement of the phase difference of low frequency distorted sinusoidal digitized signals corrupted by additive noise. Influence of SNR, THD, signal DC offset, ADC resolution, ADC range use, and number of samples per signal period can be investigated and presented in graphical form by means of the program written in MATLAB environment. The investigated methods are two modifications of classical zero-crossing based measurement, DFT based measurement, usage of phase-sensitive rectifier and two modifications of sine-wave fit algorithm. Selected results of both simulations and measurements are presented.

The paper presents a practical approach to ion selective electrodes (ISE). The behaviour of Pb⁺² ISE (ELIT8231) and Cd⁺² ISE (ELIT8241) for pure (only Cd⁺² or Pb⁺²) and mixed solutions (Cd⁺² and Pb⁺²) in static and dynamic conditions is studied. The pH variation of ISE test solution is considered in order to perform the pH correction of the ISE potentiometric selectivity coefficient determined under static conditions using a neural network processing structure. The dynamic test is performed in order to evaluate sensor’s transient response and time constant as well as ion interference and pH influence on sensor’s output. The experimental set-up is expressed by a multisensor virtual measurement system that acquires the voltage of the sensor channels, controls the ISE dynamic test and performs the data processing using a software implemented in LabVIEW.