OBSERVATIONS of GEO and LEO SATELLITES: RADIO ENGINEERING MEANS of the MYKOLAIV ASTRONOMICAL OBSERVATORY

The radio engineering means of the RI “Mykolaiv Astronomical Observatory” are fully passive. To track satellites, they use radio signals emitted by the satellites themselves. Thus, the following means were developed and put into operation: 1) Simple INTerferometer NETwork (SintNet) for monitoring the orbital position of geostationary (GEO) satellites; 2) Doppler station for clarifying the orbital elements of low Earth orbit (LEO) satellites. Two SintNets operate now: European and Chinese. The European SintNet consists of 10 stations and tracks three co-located satellites simultaneously. The Chinese SintNet consists of four stations and tracks one satellite. The positional error (standard deviation) of satellites is about 200 m. The Doppler station operates in the frequency range 430…440 MHz. Signal spectrum analysis is used to determine the frequency F(t) of the radio signal emitted by an LEO satellite and received by the station at time t. The SGP4/SDP4 analytical model of the satellite motion is applied to analyze F(t) and to clarify the elements of the satellite orbit. Errors in measuring the Doppler frequency shift and time are 4 sm/s and 30 ms, respectively.