Inversion of HF backscatter ionograms using elevation scans

Accuracy in target location by over-the-horizon radar (OTHR) can be improved when the propagation channel is known. An inversion method able to provide an equivalent electron density profile of the ionosphere from backscatter ionograms is presented in this paper. The method uses the measurements realized by the radar during elevation scans. One difficulty when using measured data is the presence of outliers and, moreover, the lack of data for low elevation and for high elevation angle. The method presented here tries to overcome these difficulties. At the end, the inversion provides parameters of an equivalent ionosphere that can be used to characterize the propagation and to convert group path into ground range.