The paper presents a comprehensive algorithm to calculate characteristics of backscatter signals (BS) within the waveguide approach. The algorithm input parameters are profiles of electron density and effective frequency of collisions that are calculated from IRI model, electric parameters and the earth surface scattering coefficient. Based on the comprehensive algorithm, one can calculate amplitude characteristics of BS signals, including the signal time base using angular coefficients of radio wave scattering from rough surface. Simulation is performed for given two-way antenna-feeders. We implemented real-time algorithms to determine the BS signal leading edge and the skip zone border. Results of simulating signal characteristics are used to analyze and interpret BS ionograms obtained from the chirp ionosonde of the Institute of Solar-Terrestrial Physics SB RAS.
Algorithm of determining ionospheric parameters from current data of backscatter sounding (BS) with continuous chirp signal is presented. Input parameters are frequency dependences of the signal propagation group path that were obtained after processing and interpretation of BS ionograms. Algorithm of BS signal leading edge inversion to parameters of electron density quasi-parabolic profile is implemented on the basis of comparing experimental and calculated minimum delays of scattered signals, bound to distance to the skip zone border.
The results of operative diagnostics for ionosphere on the base of backscatter sounding received via chirp ionosonde are presented. The results of identification for registered signals and creation of tracks are basic data for determination of maximum usable frequencies and distant-frequency characteristics of one-hop mode 1F2 for oblique propagation on the given grid of ranges, restoration of ionosphere parameters in the direction of sounding. The algorithm for transformation of the received characteristics for oblique sounding to the height-frequency characteristic of vertical sounding with the subsequent restoration of electronic concentration profile is realized.
We present techniques and algorithms for processing and interpretation of backscatter ionosphere sounding ionograms received on chirp ionosonde. The processing of experimental ionograms is carried out on the basis of basic data filtration with the subsequent compression by method of the cellular automaton. The interpretation technique for ionograms is based on use of modeling results for frequency dependences on the minimum group way in the mode of the long-term forecast and results of experimental data processing. We also present the results of operative diagnostics of HF radio channel on the base of current backscatter sounding data.
Under measurement of Doppler shift for signal frequency one define the characteristic average on time or Doppler spectrum. The use of impulses coherent sequence allows to measure Doppler shift of frequency taking into account its small variations caused by non-stationarity of the ionospheric radio channel. In the report we consider the changes of frequency Doppler shift for each beam depending on time under modeling the propagation of impulses coherent sequence through weakly non-stationary ionospheric radio channel.