Removing multiple reflections from the F2 layer to improve Autoscala performance

This work describes a simple filter able to eliminate the traces caused by second-order reflection from ionograms. This filter is applied to Autoscala in order to smooth out cases in which the autoscaling of the ionogram is mistaken because the second-order F2 layer reflection is identified as first order. A dataset of 32,626 ionograms recorded at the ionospheric observatory of Rome was used to test the filter.