Communication over long distances in an HF channel is established through ionospheric propagation. Ionosphere continuously changes due to both the effect of the sun and also other causes such as geomagnetic storms and drift. Therefore, instantaneous knowledge of the state of ionosphere has an inevitable effect on the link quality. One of the important influences of this change on communication is the Doppler shift.
In this paper, we estimate the Doppler shift in HF communications related to ionosphere by using the real data supplied by a network of GNSS receivers located uniformly over Turkey. Numerical results show that, the magnitude of the Doppler shift for 1 January, 2015 which is chosen as an example day, is around 0.2 – 0.3 Hz for the afternoon, and around 1 Hz in the morning and also the evening.