Characteristics Of Pulse Signal Research Articles

Analysis of Constraints on the Remote Application of Inverse Synthetic Aperture Laser Radar.

In order to achieve the remote application of inverse synthetic aperture laser radar for high resolution spatial situational awareness, it is essential to analyze the main factors that restrict its remote application. This study combines the range equation of inverse synthetic aperture lidar with the stimulated Brillouin threshold power equation to investigate the variation of laser transmitting power with distance. Additionally, by utilizing the excited Brillouin threshold power equation, laser linewidth formula, and pulse width characteristics of pulse signal, we examine the variation law of laser coherence that meets corresponding power requirements at different distances. The results indicate that a detection distance of 22 km and below can be achieved using continuous fiber lasers without compensation. Coherence compensation is necessary for distances between 22 km and 57 km. For distances ranging from 57 km to 3000 km, pulsed solid-state lasers are used to analyze coherence and conclude that imaging non-cooperative targets within this range is feasible. It is observed that coherence compensation is required from 57 km to 2179 km, becoming more challenging after 2000 km. Furthermore, pulsed solid-state lasers can still be utilized for imaging cooperative targets within a range of 2179-3273 km; however, coherence compensation remains necessary and becomes increasingly difficult. Finally, several coherent length compensation schemes are proposed in order to extend the imaging range of inverse synthetic aperture LiDAR to approximately 3000 km.

ON THE FEATURES OF REFLECTION OF SHEAR ELASTIC WAVE PULSES FROM A VERTICAL CRACK

A computer simulation of the characteristics of pulse signals of shear waves reflected from the edge of a vertical crack coming to the surface of the control object and a bottom crack using radiated pulses of various lengths with narrow, medium width and wide spectra was carried out. Within the limits of changing the calculation parameters, a feature of pulse reflection is established – the ratio of the maxima of the envelope pulses when reflected from a crack coming to the surface of the OK and the bottom crack is approximately 3.40 (10.6 dB), which coincides with the corresponding ratio of the maxima of the spectra. Based on the results of calculations of pulse shapes with frequency spectrum of different widths when waves are reflected from a vertical crack, the recommendation is justified not to use long pulses with narrow spectra with reduced beam resolution in the time of flight diffraction method.

Retinal spike train decoder using vector quantization for visual scene reconstruction

AbstractThe retinal impulse signal is the basic carrier of visual information. It records the distribution of light on the retina. However, its direct conversion to a scene image is difficult due to the nonlinear characteristics of its distribution. Therefore, the use of artificial neural network to reconstruct the scene from retinal spikes has become an important research area. This paper proposes the architecture of a neural network based on vector quantization, where the feature vectors of spike trains are extracted, compressed, and stored using a feature extraction and compression network. During the decoding process, the nearest neighbour search method is used to find the nearest feature vector corresponding to each feature vector in the feature map. Finally, a reconstruction network is used to decode a new feature map composed of matching feature vectors to obtain a visual scene. This paper also verifies the impact of vector quantization on the characteristics of pulse signals by comparing experiments and visualizing the characteristics before and after vector quantization. The network delivers promising performance when evaluated on different datasets, demonstrating that this research is of great significance for improving relevant applications in the fields of retinal image processing and artificial intelligence.

АНАЛИЗ РАСПРОСТРАНЕНИЯ ИМПУЛЬСНЫХ СИГНАЛОВ С МАЛЫМ ВРЕМЕНЕМ НАРАСТАНИЯ ФРОНТА С ПОМОЩЬЮ ЧИСЛЕННЫХ МЕТОДОВ

This paper presents the results of studies of transient characteristics of extended cable transmission lines. A technique for obtaining the propagation characteristics of pulse signals with a short rise time of the front based on the numerical reversal of the Laplace transform is considered. Formulas for calculating transient characteristics and reflectograms are presented. An assessment of the accuracy of the formulas used is given. Recommendations for improving the accuracy of the analysis are given. Graphs of characteristics are presented.

A Novel Electromagnetic Compatibility Evaluation Method for Receivers Working under Pulsed Signal Interference Environment

For wireless communication systems, receivers usually work under complex electromagnetic environments and are often susceptible to electromagnetic interference (EMI). With the wide application of pulse signals in various fields, the impact of pulse signals on the receivers of communication system has not been extensively studied. On the one hand, the existing receiver electromagnetic sensitivity (EMS) interference coupling effect is mainly analyzed from the perspective of energy only, without considering of different electromagnetic parameter characteristics of pulse signal, such as pulse width, repetition period, duty cycle and so on. On the other hand, there is a lack of quantitative characterization of typical performance indexes of receiver subject to pulsed interference environment, resulting in insufficient reliability and accuracy of receiver interference degree prediction and electromagnetic compatibility (EMC) evaluation. This paper focuses on the EMS interference coupling effect analysis and EMC evaluation method of receiver under pulsed interference environment. First, based on the analysis of the interference mechanism of the pulse signal on receivers, the formula for the bit error ratio (BER) is derived. Then a system model is proposed to verify the theoretical analysis results through numerical simulation. With the established relationship between the parameters of the pulsed interference and the BER performance of the receiver, a novel EMC evaluation method has been proposed. As a practical application example, the evaluation method is verified via a well-designed experiment on BeiDou Navigation Satellite System (BDS). The experiment shows that the observed phenomena are in good agreement with the conclusions of the proposed evaluation method, proving that the method is applicable to the EMC evaluation of receiver under pulsed signal interference environment.

Evaluation of the parameters of pulse signals applied in electrical stimulation using a new experimental device in the course of Medical and Biological Physics

Objective. To develop an experimental device, an algorithm for visual and analytical evaluation of the parameters of pulse signals used in electrical stimulation for further application in the course of Medical and Biological Physics.Materials and methods. The data obtained with the help of the experimental device were used as research materials. The analysis of the obtained results (characteristics of the pulse signal) was carried out with the analytical and numerical methods.Results. The proposed experimental device for receiving and analyzing pulse signals applied in electrical stimulation in education allows mastering the methods of the determination of the parameters of pulse signals, studying the methods to alter the characteristics of pulse signals used in electrical stimulation.Conclusion. The application of the experimental device makes it possible to acquire skills to evaluate the parameters and characteristics of difference pulse signals through their visualization and analytical evaluation.

STUDY OF THE DIELECTRIC CHARACTERISTICS OF INDUSTRIAL WOOD

In the article, we consider the model of pulse signal distortion in the computer sound card channel. The use of such a model allows expanding the possibilities of using computers in the researches of the wood properties in the form of various dielectric characteristics analysis, in particular using the computer sound card channel. This makes it possible to verify the state of the signal propagation channel during the experiment. This experiment researches samples of wood for the presence of defects. Also is proposed an approach to constructing the distortion model. It allows to expand the possibilities of investigating the parameters of the pulse signal and to verification the state of the channel during the research of the dielectric properties of wood. To research, a sample of wood using a computer sound card is developed a structured scheme that allows you to analyze the characteristics of pulse signals during the measurement process. To determine the dielectric parameters of different types of industrial wood is developed the software in the MATLAB environment. Using it is analyzed complex pulse signals that used during the research. In particular, were taken into account different currents of wood polarization and dielectric characteristics.

Research on adaptive pulse signal extraction algorithm based on fingertip video image

In order to solve the saturation distortion phenomenon of R component in fingertip video image, this paper proposes an iterative threshold segmentation algorithm, which adaptively generates the region to be detected for the R component, and extracts the human pulse signal by calculating the gray mean value of the region to be detected. The original pulse signal has baseline drift and high frequency noise. Combining with the characteristics of pulse signal, a zero phase digital filter is designed to filter out noise interference. Fingertip video images are collected on different smartphones, and the region to be detected is extracted by the algorithm proposed in this paper. Considering that the fingertip's pressure will be different during each measurement, this paper makes a comparative analysis of pulse signals extracted under different pressures. In order to verify the accuracy of the algorithm proposed in this paper in heart rate detection, a comparative experiment of heart rate detection was conducted. The results show that the algorithm proposed in this paper can accurately extract human heart rate information and has certain portability, which provides certain theoretical help for further development of physiological monitoring application on smartphone platform.

Mine-used cable fault location method considering transmission characteristics of pulse signal

Mine-used cable fault location method considering transmission characteristics of pulse signal

Switching performance of bistable membranes activated with integrated piezoelectric thin film transducers

In this paper we report on the fabrication of bistable micro electromechanical systems (MEMS) membranes, which have diameters in the range of 600–800 µm, a total thickness of 3.13 µm and feature integrated low power piezoelectric transducers based on aluminium nitride. To estimate the impact of the membrane asymmetry due to the integrated piezoelectric transducers, an asymmetric constant in the potential energy calculation of the bistable system is introduced, thus enabling a proper theoretical prediction of the membrane behaviour. To switch between the two bistable ground states, rectangular pulses with frequencies in the range of 50–100 kHz and a peak-to-peak voltage of 30 Vpp are applied. Two different actuation schemes were investigated, whereas one shows positive and the other negative pulse amplitudes. With a Laser-Doppler Vibrometer the velocity of the membranes during the bistable switching process is measured and integrated over time to calculate the membrane displacement in the centre. FFT (fast Fourier transform) spectra of an applied broadband white noise signal were determined in both ground states and showed a strongly decreased dominant resonance frequency in the lower ground state. The results also showed, that the asymmetry of the system causes different switching behaviours for each bistable ground state, whereas it requires less energy to switch from the lower to the upper ground state. Furthermore, it was demonstrated that a minimum of two pulses are needed for switching when using positive rectangular pulses of 30 Vpp in contrast to four when applying negative pulses. The pulse frequency causing switching was in the range of 60–110 kHz, strongly depending on the geometry and applied signal scheme. Additionally, a positive voltage offset applied to the pulse signal characteristics resulted in both a wider range of frequencies suitable for switching and in a decrease of the dominant resonance frequency, which is also beneficial for the switching process and indicates the potential for efficient switching of bistable MEMS membranes.

Research of Wireless Transmission Based on Pulse Signal

The system uses dual MCU design to achieve the acquisition and transmission of pulse signal without affecting the users sleeping process. The pulse signal is collected by infrared pulse sensor, and is wireless transferred to the personal computer by JF24C after the process of amplification, baseline correction and so on. Then personal computer analyses the signal using the method of wavelet transform algorithm. With wavelet decomposition, pulse signal can be decomposed into different scales of wavelet coefficients and recomposed according to the low-frequency coefficient of the bottom and high-frequency coefficients of various layers. During the process of wave recomposition , the coefficients related to noise can be rejected while the valuable information in the pulse signal maintained, and all the processes achieve the restoration of pulse signal. What is more, after simulating the wavelet transform algorithm using MATLAB, the consequences of this simulation indicate that multiple interferences can be effectively suppressed while keeping the pulse signal undistorted and it sustains the relevant characteristics of pulse signal.

Partial Discharge Optical Pulse Signal Characteristics for Corona Defect in Oil Immersed Transformer

Using fluorescent fiber sensor in transformer PD detection is a new method, based on the experimental platform for corona PD defect, the study has been carried out in order to show the typical corona PD defect optical pulse signal characteristics, PD single pulse waveform and pulses under industrial frequency cycle were acquired. The test results show that the optical method by using fluorescent fiber is effective in PD detection and corona PD optical pulse signals can accurately reflect the characteristics for this kind defect.

Simulation of Signals Transmitted in a Multichannel Information Speed System and Experimental Check of the Results

Characteristics of pulse signals transmitted in a multichannel information speed system widely used in physical setups of the State Research Center Institute of High-Energy Physics on a 70-GeV accelerator are studied. The simulation is carried out for various configurations of the system, taking into account special design features of the modules. The characteristics of the pulses and values of correcting (damping) components are determined, and the calculated and experimental results are compared.

4647858 Methods for overcoming transient magnetic field inhomogeneity in nuclear magnetic resonance imaging

Methods for overcoming transient magnetic field gradient inhomogeneity in a nuclear magnetic resonance imaging and/or nuclear magnetic resonance spectroscopic imaging system, wherein the inhomogeneities are induced by the pulsed magnetic field gradients utilized in the imaging process itself, provide at least one correction pulse signal during, or after, any application of the desired magnetic field to the sample-to-be-investigated in the system. At least one of the pulse signal characteristics is adjusted to oppose and substantially cancel an error-producing portion of the total magnetic field gradient in a particular direction. The magnetic field gradient correction signal(s) can be applied: during a non-selective RF pulse; immediately subsequent to an initial gradient field application (either alone or coincident with a selective 180° RF pulse); during acquisition of response signal data; or at any time to correct for inter-gradient cross-talk conditions.