摘要(英) |
The main objective of this thesis is developing the prediction of maximum usable frequencies and field strengths in the ionosphere on the HF band. Using Over-The-Horizon communication, we have the stable and secret information and do not broadcast by commercial satellites. It has low cost of terminal equipment, low power requirements and adequate signal strengths on the HF band. To communicate with the receiver, It provide the reliable quality of communication that estimate the accuracy of the broadcast.
There are four steps of the field strengths prediction on the HF band. First, to use McNish-Lincole method predicts the smoothed sunspot numbers. Comparing with the NOAA prediction, ours are close to the observation of smoothed sunspot numbers. Second, the forecast of the critical frequencies in the F2 layer of the ionosphere refers to the prediction method of the I.R.I. model. When the Kp value is smaller than three, the major prediction error is lower than 20%. Third, compute the maximum usable frequencies on the HF band. According to 0 and 4000 km of the maximum usable frequencies, we estimate the receiver distance of the maximum usable frequency by the experience formulas. Fourth, we get the forecast of field strength. Propagating the tunnel in the ionosphere, we compute the total loss on the HF band. The advantage of this prediction model is to communicate with anywhere, but the system loss is an important point. It is not a complete prediction model, because the properties of systems are different. Believe it that this is a piece of the knowledge on HF band for the researchers. |
參考文獻 |
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