Experimental verification of space radiotechnical methods for measuring the parameters of the Earth's gravitational field.

The results of two radiotechnical experiments on measuring the parameters of the Earth's gravitational field using signals from low-orbit spacecraft and global navigation satellite systems are presented. The authors' previously proposed method of measuring the acceleration of gravity using signals from a low-orbit satellite, as well as the method of measuring  the current height of the geoid based on an onboard bistatic radar system, are experimentally verified. In the first experiment, a signal from the low-orbit small spacecraft RS-44 (DOSAAF-85) with a frequency of about 2.3 GHz was used, in the second experiment primary measurement data from a bistatic radar system installed on board a foreign satellite CYGNSS. As a result of processing the measurement results obtained in the first experiment, a difference was established between the measured and model values of the gravitational acceleration of the low-orbit spacecraft with a standard deviation of 6.3 mGal. Currently, gravity acceleration measurements based on mechanical gravimeters on board a satellite are impossible due to weightlessness. In the second experiment, the measured and model values of the geoid height profile differ from each other by 13.3 cm, which meets modern requirements. The method of measuring the current geoid height based on an onboard bistatic radar system, unlike the classical method of satellite radio altimetry, allows for up to 60 reflected signals and measured heights simultaneously. The experimental results can be used to refine the model of the Earth's gravity field in remote territories and water areas, including the Arctic region.

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