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This function is evaluated by calling a particular propagation model selected for the concerned path (VLT-VLR, ILT-ILR, ILT-VLR and ILT-VLT) in the scenario. The in-built SEAMCAT models do not take into account any path-specific topographic considerations (i.e. no terrain).
Guidance on selecting the propagation model
You can select any propagation model(s) depending on the scenario and purposes of your simulation, e.g. type of radio systems and environment considered in the scenario.
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Model Frequency Range Distance Range Typical Application Area ITU-R P.1546 model (ITU-R Rec.P.1546-1 and ITU-R Rec.P.1546-4 available in SEAMCAT) 30 MHz - 3 GHz 1-1000 km Broadcasting and other terrestrial services, typically considered in cases with high mounted transmitter anttena (e.g. above 50-60 m). Note that ITU-R Rec.P.1546-4 proposes a solution where values of distances less than 1 km may occur and where short-range propagation model is not practicable and a simple means is required to converge towards free-space field strengths for arbitrarily short distances (see section 14 of ITU-R Rec.P.1546-4). Extended Hata model 30 MHz - 3 GHz Up to 40 km Mobile services and other services working in non-LOS/cluttered environment . Note that in theory, the model can go up to 100 km since the curvature of the earth is included, but in practice it is recommended to use it up to 40 km. Extended Hata-SRD model 30 MHz - 3 GHz Up to 300 m Short range links under direct-LOS assumption, important: antenna heights up to 3 m Spherical diffraction (ITU-R P.452) model Above 3 GHz Up to and beyond radio horizon Interference on terrestrial paths in predominantly open (e.g. rural) areas Free space loss model Above 30 MHz LOS-limited Fixed links and other systems/paths were direct-LOS could be assumed ITU-R P.452-14 model about 0.7 GHz to 50 GHz up to a distance limit of 10 000 km Prediction method for the evaluation of interference between stations on the surface of the Earth at frequencies above about 0.1 GHz, accounting for both clear-air and hydrometeor scattering interference propagation mechanisms. User-defined model (Propagation plug-in) model specific model specific model specific
Testing the propagation model
YOu can test the the selected propagation model separately, i.e. without setting complete scenario and running full EGE simulations. You can use the Test Propagation Models function. It is available using menu option Tools thenTest Propagation Models or directly with CTRL+SHIfT+M.
Note: It is highly recommended that user tests the newly selected propagation model before proceeding to simulations, and in particular any user-developed propagation model plugin should be tested before employing it''
Additional notes on using the Extended Hata vs. P.1546 models
The most usually used SEAMCAT in-built propagation models in typical SEAMCAT scenarios are the Extended Hata model and the ITU-R Rec. P.1546 model. Therefore, when choosing between those two models, you should be aware of their similarities and differences:
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