Software and hardware system of multi-frequency oblique sounding the ionosphere

Background. The ionosphere was and will be the main channel for the propagation of radio waves of various bands (from extremely low to super-high frequencies). A feature of this channel is the dependence of its parameters on the state of space weather. Space weather is formed primarily by processes on the Sun and by processes on Earth (to a lesser extent). High-energy processes of man-made origin can also make a certain contribution to the state of space weather. Means of oblique sounding (OS) have significant opportunities for research in the field of geospace radiophysics, study of the channel of propagation of radio waves and dynamic processes in the geospace. In this case, both own radio transmitting devices and a network of broadcasting stations can be used. With the help of OS, it is possible to cover significant regions of the globe (up to global ones), and thereby study the dynamic processes in the geospace over these regions. The purpose of this work is to briefly describe the multi-frequency multiple-path radio system of the OS ionosphere and to illustrate its performance using the example of studying dynamic processes in the geospace. Techniques and Methodology. A coherent multi-frequency multiple-path oblique sounding radio system of the ionosphere is described. It is intended for radiophysical monitoring of dynamic processes in the geospace caused by variations in space weather, the impact on the ionosphere of high-energy sources of space and terrestrial origin. The complex is capable of receiving radio signals in the low-frequency (LF) and high-frequency (HF) ranges. Original software has been developed, depending on the range of tasks to be solved. The number of radio paths and their orientation depend on the specifics of the tasks being solved. The operation of the complex is based on measurements of the Doppler shift of frequency and amplitude or phase and amplitude of the signal. The autoregressive algorithm provides a Doppler frequency resolution of up to 0.02 Hz and a time resolution of 1 min. After obtaining the time dependences of the Doppler spectra, phases and amplitudes for various radio propagation paths, further processing of the time series is performed. Results. At V. N. Karazin Kharkiv National University, a multi-frequency multi-path radio engineering complex for oblique sounding of the ionosphere has been developed and is operating, designed for radiophysical monitoring of dynamic processes in the geospace caused by variations in space weather, the impact on the ionosphere of high-energy sources of space and terrestrial origin. Conclusions. The successful functioning of the complex is demonstrated by the example of studying the dynamic processes in the geospace caused by the action of various sources of energy release.