Dmitry V. Ivanov

Optical fiber as a linear one-dimensional system with frequency dispersion

The paper presents the findings of the research into the effects of material dispersion in an optical fiber link. The general framework of normal and anomalous dispersion of the second and third orders were formulated by means of a principle of equivalence. The approach to the problem is based on a method of transforming a frequency response of an equivalent liner system into its impulse response with the use of a dispersion characteristic. This approach was used to thoroughly consider the effects of chirping, soliton (stable) propagation and collapse of solitons.

Studying the parameters of frequency dispersion for radio links of different length using SDR based sounding system

Methods and software were developed for studying parameters of frequency dispersion for radio links of different length. We used SDR based sounding system for studying a HF radio channel and determining parameters of frequency dispersion. The software component was implemented using licensed software Lab VIEW. The hardware component was implemented using a programmable transceiver USRP N210. We studied the parameters of broadband radio channels (up to 1 MHz) for near-vertical incidence skywave (NVIS) radio path (up to 500 km), as well as the parameters of the regular component of the third order phase dispersion for long-distance radio path (1000–3500 km). We studied parameters of frequency dispersion depending on the time of day, path length as well as the central channel frequency.

Fiber material dispersion effect on a matched compression of an optical pulse with frequency modulation

The paper discusses the questions of creating a mathematical model for studying the extension of a broadband pulse caused by material dispersion of an optical fiber while matched compression is also taken into account. It was shown the dependence of the dispersion widening of optical broadband signal on the optical fiber material dispersion coefficient. It was established that we can neglect dispersion impact in the case when the pulse frequency band is less than the coherence band of an optical fiber.

Optical frequency modulated pulse power losses, caused by optical fiber material dispersion

The equations were obtained to estimate the pulse power losses of broadband light pulses caused by material dispersion in an optical fiber. It was found that the dispersion caused by the extension of a signal bandwidth leads to decreasing a signal base as well as the noise immunity of a system, which uses broadband pulses.

The plotting algorithm of coherence band maps of transionospheric radio channels

The paper presents the algorithm and software for plotting coherence bands maps of transionospheric radio channels using NavGeoKom network stations data. The results of full-scale experiments of mapping for various regions of the Russian Federation are shown.

Determining method of electronic concentration total profile using oblique and transionospheric sounding data

Paper shows a method for plotting the electron concentration profile of the ionosphere on the basis of a joint approach using oblique and transionospheric sounding data. The method of determining the profile up to the global maximum height is based on the reconstruction of oblique sounding ionograms. Above the maximum, an exponential layer model is used, the initial parameters of which are transionospheric sounding data.