Ionogram

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Example ionogram with parameters and explanations
Radar principle: Depending on the frequency, the signals penetrate the ionosphere to different depths (that of the left signal is higher than that of the right).

An ionogram is the representation of the time of flight of a signal emitted by an ion probe and reflected by the ionosphere over frequency . They are used to measure the degree of ionization and the height of the ionospheric layers.

principle

The ion probe, a measuring station that works according to the radar principle, sends a signal that hits the ionosphere perpendicularly, which usually runs through a frequency range of 0.1 to 30 MHz, and measures the transit time of the received echo, from which the height of the reflection is determined .

With increasing frequency, the signal is broken back less strongly and penetrates deeper into the ionosphere before it is reflected. The deeper penetration increases the measured height of the layer, which is also called the virtual height. If the probe is above the ionosphere (satellite), the virtual height is reduced. When the so-called critical frequency is exceeded , the ionosphere is no longer able to reflect the signal.

An ionogram is helpful in determining the most favorable operating frequency for radio links in the shortwave range .

Measured values ​​in ionograms

The International Union of Radio Science (URSI) defines or standardizes the measurable parameters of the ionosphere in the context of the evaluation of ionograms in its Handbook of Ionogram Interpretation and Reduction published by WRPiggott and K.Rawer . The main ones are as follows:

Glossary of ionospheric parameters
abbreviation meaning abbreviation meaning
foF2 critical (maximum) frequency of the F 2 layer h'F the minimum, virtual height of the F-layer as a whole
foF1 critical (maximum) frequency of the F 1 layer h'F2 the minimum, virtual height of the charge maximum of the F-layer
foE critical (maximum) frequency of the E-layer h'E the minimum, virtual height of the E-layer as a whole
fxI Spread F Index hmF2 Height of the maximum of the F 2 layer
fmin minimum frequency from which a reflection occurs hmF1 Height of the maximum of the F 1 layer
hmE Height of the maximum of the E-layer

More ionograms

Web links

Individual evidence

  1. a b URSI Handbook of Ionogram Interpretation and Reduction, Second Edition (1972), Chapter 1: Fundamental Considerations and Definitions, page 19ff, [1] [2] (PDF; 3.1 MB)