Ionogram
An ionogram is the representation of the life of a radiated from an ionosonde and reflected from the ionosphere signal over the frequency. They are used to measure the degree of ionization and the height of the ionospheric layers.
Principle
The ionosonde, a working according to the radar principle station transmits a vertically striking the ionosphere signal usually passes through a frequency range of 0.1 to 30 MHz, and measures the travel time of the received echoes from which the magnitude of the reflection is determined.
As the frequency increases, the signal is less sharply broken and thus penetrates more deeply into the ionosphere, before it is reflected. Due to the deeper penetration of the measured height of the layer, which is also called virtual height increases. The probe is situated above the ionosphere ( satellite), reduces the virtual height. When the so-called critical frequency is exceeded, the ionosphere is no longer in a position to reflect the signal.
An ionogram is helpful in determining the best operating frequency for radio communications in the shortwave range.
Readings in Ionogrammen
The International Union of Radio Science ( URSI ) defined or standardized in their of WRPiggott and K.Rawer issued Handbook of ionogram interpretation and reduction the measurable parameters of the ionosphere in the context of evaluation of Ionogrammen. The most important are the following: