Abstract: In this paper an experiment to measure the frequency changes in an ionospheric channal by HFbackscatter techniques are described. The method of the digital spectra analysis are used, the variations of the Doppler frequency shifts and frequency spread versus time of the day are discussed. By comparing with the land echo spectra and response echo spectra, the results show that in HFbackscatter the contribution of the land to Doppler frequency shifts does not exist, but it affects the spectra width.