  The possibility of compensating atmospheric influence in an experiment on
precision measurement of gravitational redshift using the "RadioAstron"
spacecraft (SC) is discussed. When a signal propagates from a ground-based
tracking station to a spacecraft and back, interaction with the ionosphere and
troposphere makes considerable contribution to the frequency shift. A brief
overview of the physical effects determining this contribution is given, and
the principles of calculation and compensation of the corresponding frequency
distortions of radio signals are described. Then these approaches are used to
reduce the atmospheric frequency shift of the "RadioAstron" spacecraft signal.
The spacecraft hardware allows working in two communication modes: "one-way"
and "two-way", in addition, two communication channels at different frequencies
work simultaneously. "One-way" (SC - ground-based tracking station)
communication mode, a signal is synchronized by the on board hydrogen frequency
standard. The "two-way" (SC - ground-based tracking station - SC ) mode is
synchronized by the ground hydrogen standard. The calculations performed allow
us to compare the quality of compensation of atmospheric fluctuations performed
by various methods and choose the optimal one.
