  The method of measurement of Doppler frequency shift of ionospheric signal -
HF Doppler technique - is one of well-known and widely used methods of
ionosphere research. It allows to research various disturbances in the
ionosphere. There are some sources of disturbances in the ionosphere. These are
geomagnetic storms, solar flashes, metrological effects, atmospheric waves.
This method allows to find out the influence of earthquakes, explosions and
other processes on the ionosphere, which occur near to the Earth. HF Doppler
technique has the high sensitivity to small frequency variations and the high
time resolution, but interpretation of results is difficult. In this work we
make an attempt to use GPS data for Doppler measurements interpretation.
Modeling of Doppler frequency shift variations with use of TEC allows to
separate ionosphere disturbances of medium scale.
