English: This ionogram shows a well-formed F-Layer with a peak ionization at around 220 km. There is also a less obvious E-Layer at an altitude of about 110 km. The ionogram clearly shows how the transmitted digisonde signal splits into reflected ordinary and extraordinary waves. The ionogram chart and the parameter FoF2 in the list on the left side of the chart, show that the highest frequency that will be reflected from the ionosphere for vertical incidence (ie., for a radio wave traveling straight up from the ground) is 4.8 MHz.