East-Siberian Center for the Earth's Ionosphere Research (SDC ESCEIR)

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Mathematical modelling and information support subdivision

VS data on-line diagnostics

The real-time radiosignals characteristics calculation algorithm from current VS data is carried out according to the following scheme (V.P.Grozov,G.V.Kotovitch,V.E.Nosov,S.N.Ponomartvhuk, S.V.Pushkarev,L.P.Sergeeva,V.V.Khakhinov. Real time decameters radio systems characteristics calculation by ionosphere vertical sounding data. //Radiophisica i electronica : problemy nauki i obutcheniya. Irkutsk, 1995. P.63-66). We carry out VS ionograms processings in order to pick out signals with significant amplitude. After that, we eliminate the refleceted signal with multiples greater than one, carry out the identification, and build traces. By building traces we mean "binding" separated marked ionogram points to continuous lines. After trace building we calculate ionospheric parameters: critical frequencies and minimum reflection heights for every ionospheric layer. If we can correctly identify all layers, then we can carry out a automatic oblique propagation characteristics calculation from the given traces.

In the figure we present the program package functional diagram for automatic selection of connected radioline optimum working frequencies from chirp signal ionosphere vertical sounding. The integral span - program "manager" can perform the following set of functions:

• Database servicing;
• radioline selection;
• ionogram and calculation results display on monitor;
• VS ionogram interpretation and processing program initiation;
• Radiosignal characteristics calculation program initiation;
• SW radiochannel characteristics calculation from given technical parameters.

We assume that the VS experimental ionogram after a preprocessing will be stored in the ionogram database (ionogram catalogue and ionograms on hard drive). In the dialog mode the operator can set radioline parameters: radioline geometry , chirp ionosonde and connected system technical parameters. After the VS ionogram processing from amplitude reliefs, building height-frequncy characteristic (HFC) traces and HFC processing (binding points along layers) we can perform a radiosignals characteristics calculation. By tracing into account energetic relation between the signal level and the noise level we can determine optimum working frequencies (Uryadov V.P. Optimal working frequencies selection for wide and short-band connected signal by continuous chirp signal ionospheric sounding. NIRFI Preprint N374. Nizhni Novgorod, 1993. 12 p.).