1. Coverage and Propagation Models
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2. Coverage
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3. Link budget
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4. Propagation Models Ten propagation models are supported:
- ITU-R P (Detailed terrain)
- DETVAG 90/FOA (Detailed terrain)
- ITU-R P.370-7
- Longley-Rice
- Okumura-Hata/COST Hata
- COST Walfish - Ikegami
- ITU-R P.452-9
- ITU-R P.619
- Free Space
- CRC (Detailed terrain), by special licensing only
Attenuation due to atmospheric gases can be included (ITU-R P for terrestrial, P for space)
HF Planning with ITS HF software:
-VOACAP/ICEPAC/REC533 (point-to-point)
-VOAAREA/ICEAREA/RECAREA (point-to-area)
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5. Propagation mechanisms
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6. Propagation Models Model Frequency range Terrain dependence
Antenna height above ground
Calculation speed
Free space
No frequency limitation
No terrain dependence. Gives the same transmission loss in all directions.
The model assumes no ground influence.
Very fast
Longley-Rice
20 MHz to 40 GHz
No terrain dependence. Terrain influence is given as a terrain roughness parameter to the model, entered by the operator. Gives the same transmission loss in all directions.
0.5 – 3000 m. The 3000 m above ground level antenna height limitation does not significantly reduce accuracy for higher antenna heights.
ITU-R P.370-7
30 – 1000 MHz
Terrain information is taken from the ITU Digitized World Map to determine the path lengths over land and over sea. The operator can enter a terrain roughness parameter. Gives the same transmission loss in all directions, if the path is wholly over land or sea.
One antenna in the interval 1.5 –
40 m and the other antenna 37.5 – 1200 m above ground.
Okumura-Hata/COST-231-Hata
150 – 2000 MHz (no hard limit at 2000 MHz – can be used for 2 GHz cellular applications)
No terrain dependence. The operator can enter a type of environment (urban, suburban, rural etc.). Gives the same transmission loss in all directions. The distance is limited to 1 – 20 km.
One antenna in the interval 30 –
200 m and the other antenna 1 – 10 m above ground.
COST-231 – Walfish-Ikegami
800 – 2000 MHz (no hard limit at 2000 MHz – can be used for 2 GHz cellular appli­cations)
No terrain dependence. The operator can enter the type of environment and parameters describing the buildings and streets. Gives the same transmission loss in all directions. The distance is limited to 0.02 – 5 km.
One antenna in the interval 4 – 50 m and the other antenna 1 – 3 m above ground.
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7. Propagation Models Model Frequency range Terrain dependence
Antenna height above ground
Calculation speed
ITU-R P.526-6
From about 500 MHz to above 100 GHz. For situations where one or both of the antennas are high above ground (such as in ground-to-air and air-to-air links) it can be used from 100 MHz.
Terrain information taken from the height and terrain classification databases. Gives fully terrain dependent transmission loss, however neglecting the electrical characteristics of the ground and ground reflections.
Valid for all antenna heights.
Fast
Detvag-90/FOI
10 kHz to above 100 GHz. Ionosphere propagation is not considered.
Terrain information taken from the height and terrain classification databases. Gives fully terrain dependent transmission loss.
Note that Detvag includes a number of selectable models and can be set to be non-terrain dependent as well. This is however not the normal use.
The fast methods (non-GR ground wave) have limitations on the maximum antenna height:
Frequency Height 30 MHz 300 m
Note that for most practical cases the influence of the ground (apart from diffraction) can be neglected above 1 GHz even at low antenna heights. The default methods of Detvag (“Quick” settings) therefore do not have the above limitations above 1 GHz.
Fast-to-medium for most settings. Very slow when used with the GR methods (for ground wave below about 30 MHz)
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8. Propagation Models Model Frequency range Terrain dependence
Antenna height above ground
Calculation speed
CRC
30 MHz to above 100 GHz
Terrain information taken from the height and terrain classification databases. Gives fully terrain dependent transmission loss.
Valid for all antenna heights.
Slow
ITU-R P.452-9
0.7 GHz to above 100 GHz
Diffraction calculations are performed using the P.526 method, giving terrain dependence. Rain scatter parameters are read from the ITU Digitized World Map. Otherwise the model is not terrain dependent.
The model is intended for stations on the surface of the earth. Antenna heights should be less than a few hundred metres.
Fast for most settings. Slow for very long distances.
ITU-R P.619-1
From about 300 MHz to above 20 GHz. The lower limit is due to neglecting of ionospheric scintillation. The upper limit is due to the modelling of tropospheric scintillation.
No terrain dependence, apart from consideration to shadowing by the earth considered as a sphere.
The model is applicable for earth-space paths, with the space station being at non-geostationary orbit height or above and the earth station being on the surface of the earth, with antenna height less than a few hundred metres.
Very fast
ITU-R P and P.618-6
1 – 350 GHz.
P for space paths does not include the oxygen gap consideration at 60 GHz.
Not applicable. The transmission loss calculated by the atmospheric attenuation models is added to the loss calculated by the selected propagation model.
No antenna height dependence is included (apart from the satellite height for the space path model). This limits the applicability to heights up to a few thousand metres for terrestrial paths.
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9. Frequency range and Accuracy
Propagation Models
Table 4.1: Default settings for Detvag-90/FOI propagation model (Quick tab, Low/High accuracy)
Method 
Frequency range and Accuracy
Below 30 MHz
30 – 1000 MHz
Above 1000 MHz
Low
High
Spherical earth
GR Start
GR Millington extended
Old with conductivity
None
Diffraction
No. of obstacles -
Giovaneli 3
GTD 7
Urban
Add cover height
Vegetation
Effective antenna height
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10. Propagation Models Application Frequency Recommended propagation model
Ground-to-ground
<30 MHz, ground wave
Detvag-90/FOI. Quick/Low if terrain data is not available; otherwise Quick/High. Start with very low resolution in Coverage calculations to check the calculation speed before making detailed calculations.
>30 MHz
Terrain data available:
Detvag-90/FOI, Quick/Low if antenna height conditions are fulfilled. Otherwise Detvag-90/FOI, Advanced, GTD. CRC (if available) is applicable irrespective of antenna heights.
No terrain data available:
Longley-Rice.
For specific services: Broadcast: ITU-R P.370 Cellular: Okumura-Hata/COST-231-Hata or COST-231 – Walfish-Ikegami
Ground-to-air
Detvag-90/FOI. Quick/High.
30 – 100 MHz
Terrain data available: Detvag-90/FOI, Advanced, GTD. CRC (if available) is applicable irrespective of antenna heights.
No terrain data available: Longley-Rice
>100 MHz
Terrain data available: ITU-R P.526 is the first choice due to its fast calculation speed.
Detvag-90/FOI, Advanced, GTD. CRC (if available) is applicable irrespective of antenna heights. These should also be used if there is specific need to account for ground reflections to show occurrence of areas of increased transmission loss due to cancellation between the direct ray and ground reflected rays (normally only relevant over water).
Air-to-air
>30 MHz (lower frequencies usually of little interest)
Longley-Rice as an overall method at heights where terrain obstructions are not important
ITU-R P.526 for cases where the terrain influence due to obstructions are of interest
Earth-to-space
>50 MHz
ITU-R P.619. Make sure to select the Space paths atmospheric attenuation model.
Space-to-space
All frequencies
Free space. Note that Class of Station should be set to Space station for both stations if the calculation is to account for shadowing by the Earth.
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11. Coverage Single transmitter coverage or Multiple transmitter coverage
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12. Selectable calculations (Single station)
Field strength [dBµV/m]
Power flux density [dBW/m2]
Signal strength [dBµV]
Received power [dBm]
Transmission loss [dB]
Clearance [%]
S/I [dB]
Required antenna height [m]
Terrain clearance angle [º]
Neighbour cells, noise & interference limited
Adjacent cell coverage
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13. Selectable calculations (Multiple stations)
Field strength [dBµV/m]
Power flux density [dBW/m2]
Signal strength [dBµV]
Received power [dBm]
Best server, noise limited or interference limited
No of servers, noise limited or interference limited
Maximum clearance, minimum clearance [%]
Maximum required antenna height, minimum required antenna height [m]
Composite coverage, S/I [dB]
Number of interferers
Worst interferer
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14. Best server Best Server, noise limited
maximum signal of all stations in the calculation
signal greater than or equal to the receiver sensitivity plus margin
Best Server, interference limited
maximum SIR of all stations in the calculation
SIR greater than or equal to the receiver required SIR plus margin
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15. Number of servers Number of Servers, noise limited
signal greater than or equal to the receiver sensitivity plus margin
Number of Servers, interference limited
SIR greater than or equal to the receiver required SIR plus margin
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16. Clearance
Maximum clearance calculates the clearance from all stations to the antenna at each point and then displays the value which fulfils the criterion for one of the stations. [%]
Minimum clearance calculates the clearance from all stations to the antenna at each point and then displays the value which fulfils the criterion for all of the stations.[%]
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17. Required antenna height
Minimum required antenna height gives the required antenna height to fulfil the clearance criterion from all of the involved stations
Maximum required antenna height gives the required antenna height to fulfil the clearance criterion from one of the involved stations
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18. Probability calculations
Normally the calculation results are the local mean values, which are the direct output from most of the propagation models. If the Probability check box is checked, the result is adjusted based on the assumption that the signal has a log-normal probability density function. All probability calculations are performed for the contour probability (and not the area probability).
Standard deviation can be fixed or set by the software (normally 8.3 dB)
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19. Probability calculations
Fixed level
Calculation of the probability that a user-defined level achieves. The result can be plotted for different percentages but the level is fixed.
Fixed probability
Calculation of the result levels for a given probability. The result is then plotted for different levels but with fixed probability.
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20. Result Presentation A three-level result Long-Lat grid
Relief background
Radio station
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21. Resolution Resolution Number of terrain raster points
Number of calculation points for Area
Number of calculation points for Line
Very Low Resolution
200x200 =
25x25 = 625. For very rough estimates or calculations involving an extremely large number of transmitters in a smaller area.
25 points on line
Low Resolution
400x400 =
50x50 = For rough estimates.
50 points on line
Average Resolution
800x800 =
100x100 = Default setting which is adequate for most purposes. This gives a good visual appearance on screen and printouts, without requiring excessive calculation times.
100 points on line
High Resolution
1600x1600 =
200x200 = For very detailed calculations.
200 points on line
Very High Resolution
3200x3200 =
400x400 = For extremely detailed calculations.
400 points on line
User defined
The resolution given in meters is be entered by the user.
The resolution given in meters is be entered by the user. The same resolution is used in both directions.
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22. Interference limited coverage
It is possible to select different propagation models for the wanted and interfering signal
Applies for the following calculations
S/I (single station)
Interference limited best server (multi-station)
Interference limited No. of servers (multi-station)
Composite S/I (multi-station)
Number of interferers (multi-station)
Worst interferer (multi-station)
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23. Population coverage The total
number of population that is covered with a certain field strength, received power level etc.
percentage coverage of the total population in a defined calculation area can be calculated.
Requires a database in the appropriate format, with information on the number of inhabitants within a certain square area.
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24. Coverage calculation results: Post calculations
Description (single RESULT marked)
Description (multiple RESULTS marked)
Best server…
Not applicable.
Identifies the best server by comparing the result values from all marked results. All the results must be of the same calculation type and based on a calculation for a single station. The results must be of the calculation type Field strength, Signal strength, Received power or S/I. Probability calculations are also possible.
In order to be a best server at a certain location the station must fulfil:
• Maximum signal of all stations in the calculation
• Signal greater than or equal to a user defined planning level.
Upon executing this command the user is prompted by a dialogue to set/accept the planning level threshold.
Composite
Calculates the composite coverage with the highest value of the selected results as the result. All the results must be of the same calculation type. Single station results and multiple stations results can be used together. The results must be of the calculation type Field strength, Signal strength, Received power or S/I. Probability calculations are also possible.
For single station results Transmission loss results also can be used. The lowest value is presented as the result.
Number of servers…
Identifies the number of servers by comparing the result values from all marked results. All the results must be of the same calculation type and based on a calculation for a single station. The results must be of the calculation type Field strength, Signal strength, Received power or S/I. Probability calculations are also possible.
In order to be accepted as a server the station must have a value exceeding the planning level. Upon executing this command the user is prompted by a dialogue to set/accept the planning level threshold.
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