Open Access
Table 2
Classification of the Ionograms based on the frequency range affected by the TIDs signature.
| Class | Affected frequency range |
|---|---|
| 1. | frange < 0.5 MHz |
| 2. | 0.5 MHz < frange < 1.5 MHz |
| 3. | frange > 1.5 MHz |
| 4. | Most of the F trace is distorted |
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