An introduction to the digitalizing conversion of film ionogram
电离层胶片频高图数字化转换分析

The ionograms acquired with the ionospheric vertical sounding method is the oldest data in the history of ionospheric research. Using of modern microelectronics and computer technology to digitalize, analyse and preserve the huge amount of historical film ionogram has become more and more important and urgent. There are more than thirty years data of ionorams in film format at the Wuhan station. It is a very essential work to preserve, protect and utilize these valuable historical data. This paper introduces the progress of our project in using digital image processing technologies to digitalize, correct and repair of film ionograms and convert them in an exchangeable format. An analysis and conversion software has been developed for the film ionogram analysis, and then it utilizes the SAO Explorer program to scale Wuhan film ionogram. Some examples have been presented to show that our method is reliable and the developed software is user friendly. Our work provides a positive solution in digitalization and analysis of huge amount of historical film ionograms. With the on-going of the project, huge amount of ionospheric parameters and electron density data will be available to the ionospheric community.