This propagation model is fully described in Recommendation ITU-R P.1546-5. Only the land terrain profiles are implemented in SEAMCAT. The ranges of application are the same as for the ITU-R P.1546-4, except for the Tx-Rx horizontal distances that can be smaller than 1 km. In the section about Algorithm description, only the parts of Recommendation ITU-R P.1546-5 that are different from Recommendation ITU-R P.1546-4 are listed.
It must be emphasised that the measurements and modelling in this Recommendation intrinsically include the effect of terminal clutter, so it would be inappropriate to add a calculation of clutter separately.
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Figure 478: SEAMCAT Interface to the ITU-R P.1546-5 propagation model
Table 89: ITU-R Recommendation P.1546-4 propagation model
Description | Symbol | Type | Unit | Comments |
Variations |
|
|
| Variation in basic transmission loss |
Time Percentage | p | D | % | Time variability for which the field strength value is exceeded: 1% - 50% |
General environment around the Rx |
|
|
| Environment of the propagation around the Rx with representative values of clutter height in m: rural (10), suburban (10), urban (20), dense urban (30) |
Representative clutter height around the Rx | R2 | S | m | User-specified clutter height at the Rx which overwrites any predefined value when selected |
General environment around the Tx |
|
|
| Environment of the propagation around the Tx with representative values of clutter height in m: rural (10), suburban (10), urban (20), dense urban (30) |
Representative clutter height around the Tx | R1 | S | m | User-specified clutter height at the Tx which overwrites any predefined value when selected |
Location probability | q | D | % | Location variability: 1% - 99% (default value: 50%) |
User specified standard deviation |
| S | dB | User-specified standard deviation value which overwrites any predefined value when selected |
Area of location variability |
|
|
| 500x500 m, < 2 km radius, < 50 km radius |
System |
|
|
| Mobile, broadcasting digital and broadcasting analogue |
Average profile height around the Rx |
| S | m | The average level of the terrain height between distances of 3 and 15 km from the Rx antenna in the direction of the Tx antenna. If Tx-Rx distance d is less than 15 km, then the terrain height is averaged between distances 0.2 d and d km. |
Average profile height around the Tx |
| S | m | The average level of the terrain height between distances of 3 and 15 km from the Tx antenna in the direction of the Rx antenna. If Tx-Rx distance d is less than 15 km, then the terrain height is averaged between distances 0.2 d and d km. |
Terrain clearance angle (at the Rx) | qtca | S | deg | The h2 terminal's clearance angle as calculated in Section 11, noting that this is the elevation angle relative to the local horizontal
|
Terrain clearance angle (at the Tx) | qeff1 | S | deg | The h1 terminal’s terrain clearance angle calculated using the method in Paragraph 4.3 case a), whether or not h1 is negative |
Terrain height above sea level at the Rx | S | m | Terrain height in meters above sea level at the receiver/mobile. This parameter is used in combination with the antenna height (from the Rx local environment) and the average profile height around the Rx to compute the effective antenna height. | |
Terrain height above sea level at the Tx | S | m | Terrain height in meters above sea level at the transmitter/base. This parameter is used in combination with the antenna height (from the Tx local environment) and the average profile height around the Tx to compute the effective antenna height. | |
Terminal designations |
|
|
| When selected the algorithm will consider the option a), b) and c) of ITU-R. 1546-5 Annex 5 §1.1. By default it is selected. |