IKBFU's Vestnik

2014 Issue №04

Numerical simulation of the ionospheric effects of geomagnetic storm on 2—3 may 2010 at the HF radio wave propagation in the low-latitude region

Abstract

For the first time we used a global three-dimensional theoretical model of the thermosphere-ionosphere system for the description of inhomogeneous anisotropic medium in the simulation of radio wave propagation. It is shown that the results obtained with joint using GSM TIP model and radio wave propagation model adequately describe HF radio paths in the Earth's ionosphere in quiet conditions and at the recovery phase of geomagnetic storm.

Download an article

The features of electron density behavior in the ionosphere-plasmasphere system above equatorial station Jicamarca in the end of September 2011

Abstract

We present the analysis of the ionosonde and incoherent scatter radar (ISR) data of ionospheric parameters over Jicamarca (Peru) in quiet conditions and during geomagnetic storms on 22—29 September 2011. According to ISR data the estimation of the ionospheric contribution to the Total Electron Content (TEC) was carried out. These observation data are compared with GSM TIP model calculation results. The features of the electron density Ne behavior in the equatorial ionosphere and, in particular, F3 layer behavior, were identified. The agreement of the model calculation results and observation data analysis was obtained in quiet conditions and during geomagnetic storms.

Download an article

Application the theory of an optimum detection for a spatial resolution of signals

Abstract

The article deals with application of the theory of optimum detection to the azimuth resolution of two sound sources. This paper compares the solutions based on maximum likelihood method with the classical approach (Rayleigh's approach). Furthermore, the computer model and the testbench (experimental apparatus) have been created for an extensive analysis of the obtained solution. Our experimental and model results demonstrate a significant advantage of the solution obtained by using the theory of optimum detection. The purpose of this study is present the possibilities and advantages of the maximum likelihood method.

Download an article

Way of shortening the inclusion of antennas of the transducer of the impedance shoulder vibrator

Abstract

A method is proposed shortening of vibrator antenna. Capacitive reactance is compensated offset by the inclusion of the extension of the inductance coil in the shoulders vibrator. This interpretation of the short tape antenna gives the opportunity to increase the power of the radiation virtually reducing the efficiency of the antenna system, in a result of losses on the inductive element.

Download an article

The properties of a tunable frequency oscillator with the partial inclusion of the transistor in the circuit

Abstract

The properties of a tunable frequency oscillator with a circuit between the collector and the base of the partial inclusion of the transistor in the circuit were studied using a method based on the presentation of bipolar transistor equivalent active two port circuit with negative conductivity.

Download an article

Building transmitter circuit for the study of parameters of system of secondary emitters

Abstract

Suggest a method for constructing a system of magnetic coils, of the workspace in which excited облучающее sample magnetic field used to study the parameters of the system of secondary emitters. Theoretically formulated and practically implemented model of the feed, providing the creation of a uniform magnetic field on the stage. The measurements of the distribution of magnetic field in облучателе to judge the appropriateness of the use of the system in experimental techniques.

Download an article

Evaluation of error probability in determining of reception time of RZS in the presence of white noise

Abstract

The error origins in determining of reception time of radio probing signal are considered in this article. Also the method of error probability calculation was offered in this work. The analysis of maximum probability of such error was carried out for phase-shift keyed signal on the base of Barker’s code and radio signal without intrapulse modulation.

Download an article

Applying artificial neural networks for prediction of radiowave propagation features

Abstract

Possibility of artificial neural networks application in purpose of propagation loss prediction and defining of statistics parameters: standard deviation of signal level, probability of area coverage and probability of exceeding of threshold is examined. Neural networks were created for prediction of these parameters. Performed accuracy is estimated.

Download an article

Dipolarization of the earth magnetic field and charge particles precipitation from the magnetic flux tube

Abstract

During the expansion phase of the substorm in the nightside magnetosphere enhancement of the magnetic field and decrease the plasma pressure is observed simultaneously. Enhancement of the magnetic field is recorded at first in the tail of the magnetosphere, and then at more closer distances from the Earth. This process takes a few minutes and covers the region in the magnetosphere of 10 Earth radii. One of possible explanations of this phenomenon is associated with cooling magnetic flux tubes caused by the precipitation of the energetic particles in the ionosphere. We have made evaluation of the effectiveness of this mechanism.

Download an article