Vigas

Atoll provides several tools to enable you to evaluate the line of sight around a site or between candidate sites.

In this section, the following are explained.

• "Displaying the Line of Sight Area Around One Site" on page 189

• "Analysing the Line of Sight Between Candidate Sites" on page 191

• "Displaying the Terrain Profile Between Candidate Sites" on page 193

• "Displaying the Terrain Profile Between Candidate Sites" on page 193

5.2.2.1 Displaying the Line of Sight Area Around One Site

Atoll allows you to display the line-of-sight area around a site in the map window.

To display the line-of-sight area around a site:

1. Right-click the site either on the map, or in the Sites folder of the explorer window’s Network tab. The context menu appears.

2. Select Visibility > Line of Sight Area from the context menu. The Line of Sight Parameters dialog box appears.

Alternatively, you can create a new site by entering its coordinates and properties as described in "Site Properties" on page 188, by right-clicking the Sites folder and selecting New from the context menu.

If you are creating several sites at the same time, or modifying several existing sites, you can do it quickly by editing or pasting the data directly in the Sites table. You can open the Sites table by right-clicking the Sites folder on the Network tab of the explorer window and selecting Open Table from the context menu. For information on copying and pasting data, see "Copying and Pasting in Tables" on page 65.

3. Under Transmitter, select one of the following options to specify the height of the antenna on the transmitter side and specify a Default height applicable to that option:

• Site support: Select this option to specify a transmitter height that uses the Support height from the site proper-ties.

• Relative to the ground: Select this option to specify a transmitter height above the ground in Default height.

• Relative to clutter: Select this option to specify a transmitter height above the clutter height in Default height.

4. Under Receiver, select one of the following options to specify the height of the antenna on the receiver side and specify a Default height applicable to that option:

• Relative to the ground: Select this option to specify a receiver height above the ground in Default height.

• Relative to clutter: Select this option to specify a receiver height above the clutter height in Default height.

• Per clutter class: Select this option to use the receiver height above the clutter height that is defined per clutter class on the Clutter tab.

5. Define the Maximum distance around the selected site to be considered in the line-of-sight analysis.

6. Define the Resolution.

7. Under Earth curvature factors, define the First k value and the Second k value.

8. Under Penetration condition, define the following parameters:

a. Take clutter into account in diffraction: Select this option to use clutter information when calculating diffraction in the line of sight.

b. Define the type of clearance to calculate by selecting one of the following items:

• Line of sight clearance: Select this option to study the direct line of sight between the transmitter and receiver sites.

• Ellipsoid clearance: Select this option to study the percentage of clearance of the Fresnel ellipsoid. Enter the required percentage of clearance of the lower half of the Fresnel ellipsoid in the Target clearance box. In Frequency band, select the frequency band to use when calculating the line of sight.

9. Click the Clutter tab. On the Clutter tab you can set clutter-related parameters that will be used to calculate the line-of-sight area. The settings on the Clutter tab are independent from any clutter parameters you might have set for the propagation model. For each clutter class, you can set the following:

• Receiver height (m): Specify a receiver height above the the clutter height for each clutter class. This is the value that will be taken into consideration if you selected Per clutter class under Receiver on the Calculation Parame-ters tab.

• Horizontal clearance around transmitter and receiver (m): Specify a clearance around each site for each clutter class. The clearance is used when calculating diffraction. Both ground altitude and clutter height are considered along the whole profile except over a specific distance around the sites (clearance), where Atoll bases its calcula-tions only on the DTM.

10. Click the Display tab. On the Display tab, you can define how the line-of-sight areas will be displayed on the map. You can select one of the following display options:

• One area per site: Select this option to display a of-sight area for each site and then define the colour the line-of-sight areas will be displayed in:

• Automatic colour: If you select this option, Atoll will automatically assign a different colour to each line-of-sight area, and you will be able to distinguish the line-of-line-of-sight areas for each site.

• Unique colour: If you select this option, Atoll will display all line-of-sight areas in the same colour, and the resulting display will show the cumulative line-of-sight areas.

Set the transparency of the displayed line-of-sight area, by moving the slider.

11. Select the Add to legend check box to add the options defined on the Display tab to the Legend. For information on the Legend window, see "Displaying the Map Legend" on page 42.

12. Click OK. Atoll displays results on the map.

To delete the line-of-sight area around a site:

1. Right-click the site either on the map, or in the Sites folder of the explorer window’s Network tab. The context menu appears.

2. Select Visibility > Delete Line of Sight Area from the context menu.

To display the line of sight area around all sites in your Sites folder (or in the computation zone, if any) you should right-click the Sites folder and select Visibility > Overlapping Area instead. See "Tools in Atoll for Finding New Sites" on page 195.

5.2.2.2 Analysing the Line of Sight Between Candidate Sites

In Atoll, you can analyse the line of sight (LOS) between candidate sites for different frequency bands. The analysis can be done for one particular site or for a group of sites.

In the first case, Atoll performs the analysis between the selected site and all sites located within the computation zone. If there is no computation zone, all sites of the Atoll document will be considered as candidates.

When run on a group of sites, both focus and computation zones can be used. Atoll calculates a line of sight between each site located within the focus zone and each site within the computation zone. If no focus zone exists, the analysis will be done between the sites of the computation zone.

For information on the focus zone, see "Focus Zone" on page 50 and for information on the computation zone, see "Compu-tation Zone" on page 49.

To calculate a LOS report for one particular site:

1. Right-click the site either on the map or in the Sites folder of the explorer window’s Network tab. The context menu appears.

2. Select Visibility > Line of Sight Report from the context menu. The Line of Sight Parameters dialog box appears.

3. Click the Calculation Parameters tab.

4. Under Transmitter, select one of the following options to specify the height of the antenna on the transmitter side and specify a Default height applicable to that option:

• Site support: Select this option to specify a transmitter height that uses the Support height from the site proper-ties.

• Relative to the ground: Select this option to specify a transmitter height above the ground in Default height.

• Relative to clutter: Select this option to specify a transmitter height above the clutter height in Default height.

5. Under Receiver, select one of the following options to specify the height of the antenna on the receiver side and specify a Default height applicable to that option:

• Site support: Select this option to specify a receiver height that uses the Support height from the site properties.

• Relative to the ground: Select this option to specify a receiver height above the ground in Default height.

• Relative to clutter: Select this option to specify a receiver height above the clutter height in Default height.

• Per clutter class: Select this option to use the receiver height above the clutter height that is defined per clutter class on the Clutter tab.

6. Define the Maximum distance around the selected site to be considered in the line-of-sight analysis.

7. Define the Resolution.

8. Under Earth curvature factors, define the First k value and the Second k value.

9. Under Penetration condition, define the following parameters:

a. Take clutter into account in diffraction: Select this option to use clutter information when calculating diffraction in the line of sight.

b. Define the type of clearance to calculate by selecting one of the following items:

• Line of sight clearance: Select this option to study the direct line of sight between the transmitter and receiver sites.

• Ellipsoid clearance: Select this option to study the percentage of clearance of the Fresnel ellipsoid. Enter the required percentage of clearance of the lower half of the Fresnel ellipsoid in the Target clearance box. In Frequency band, select the frequency band to use when calculating the line of sight.

10. Click the Clutter tab. On the Clutter tab you can set clutter-related parameters that will be used to calculate the line of sight. The settings on the Clutter tab are independent from any clutter parameters you might have set for the prop-agation model. For each clutter class, you can set the following:

• Receiver height (m): You can define a receiver height for each clutter class. It is not used when calculating the line of sight between existing sites.

• Horizontal clearance around transmitter and receiver (m): If you want, you can define a clearance around each site for each clutter class. The clearance is used when calculating diffraction. Both ground altitude and clutter height are considered along the whole profile except over a specific distance around the sites (clearance), where Atoll bases its calculations only on the DTM.

11. Click the Table tab. On the Table tab you can define the contents of the report. Atoll displays a default set of fields and lets you select other information to be included in the report.

a. Click Add. The Field Selection dialog box appears.

b. In the Field selection dialog box, select the fields that you want to display in the report. You can select contiguous fields by clicking the first field, pressing SHIFT and clicking the last field. You can select non-contiguous fields by pressing CTRL and clicking each field separately.

• To select a field to be included in the report, select the field in the Available fields list and click to move it to the Selected fields list.

• To remove a field from the list of Selected fields, select the field in the Selected fields list and click to remove it.

• To change the order of the fields, select a field and click or to move it up or down in the list. The objects will be displayed in the order of the fields in the Selected Fields list, from top to bottom.

c. Click OK to return to the Table tab.

12. Click OK. Atoll displays the selected results in the Terrain Sections table. As well, Atoll displays a terrain section on the map between each pair of sites.

The Terrain Sections table contains the following default information for each pair of sites, Site1-Site2. Site1 is either the selected site or the studied site within the focus zone or the computation zone if no focus zone is defined. Site2 is a candidate site within the computation zone if available.

• Site1: Site1 is the transmitting site of the pair of sites.

• Site2: Site2 is the receiving site of the pair of sites.

• Frequency (MHz): The mean frequency used to calculate the line of sight between the transmitting site and the receiving site.

• Antenna 1 Height/Ground (m): The height of the transmitting antenna.

• Antenna 2 Height/Ground (m): The height of the receiving antenna.

• Custom heights: The value is False when the antenna heights of the terrain section are those that were calculated by line of sight report. If any of the antenna heights is modified, then it is set to True.

• Line of Sight (k1) (%): The clearance or penetration of the Fresnel ellipsoid in percentage for the first k factor value.

The result can be between -100 and 100%. A value from -100 to 0% corresponds to the percentage of penetration of the upper half of the Fresnel ellipsoid. A value from 0 to 100% corresponds to the percentage of clearance of the lower half of the Fresnel ellipsoid (see Figure 5.2).

• Line of Sight (k2) (%): The clearance or penetration of the Fresnel ellipsoid in percentage for the second k factor value.

• Distance (m): The distance between the sites.

• Direction 1 (°): The angle from Site1 to Site2 in the horizontal plane.

• Direction 2 (°): The angle from Site2 to Site1 in the horizontal plane.

• Tilt 1 (°): The tilt angle from Site1 to Site2 in the vertical plane.

• Tilt 2 (°): The tilt angle from Site2 to Site1 in the vertical plane.

The results provided in the Terrain Sections table are calculated in real time. Therefore, you can modify the frequency or the antenna heights and immediately see the impact of the modifications on the line of sight results.

You can remove the line-of-sight sections by selecting Visibility > Delete Terrain Sections from the site’s context menu.

If necessary, you can also calculate a LOS report for all sites by selecting Visibility > Line of Sight Report from the context menu of the Sites folder. You can remove the terrain sections by selecting Visibility > Delete Terrain Sections from the context menu of the Sites folder.

After you have calculated the LOS report, you can change the terrain section display on the map, analyse the terrain profile of a calculated terrain section, or create links with them:

• "Displaying the Terrain Sections on the Map" on page 192

• "Displaying the Terrain Profile of an Existing Terrain Section" on page 193

• "Creating a Microwave Link with a Terrain Section" on page 194.

5.2.2.2.1 Displaying the Terrain Sections on the Map

The terrain sections displayed on the map are coloured by default according to the percentage of clearance or penetration of the Fresnel zone:

• Green: By default, a terrain section is displayed on the map in green if it is completely unobstructed (i.e., if the visibility is over 100 m.).

Figure 5.2: Line of sight clearance

• Orange: If the terrain section is partially obstructed (i.e., if the visibility is between 0 m. and 100 m.), it is displayed in orange on the map.

• Red: If the terrain section is completely obstructed, it is displayed in red.

You can modify the colours and value intervals in order to make their display properties more meaningful to you.

To colour terrain sections according to the percentage of clearance or penetration of the Fresnel zone 1. Click the Geo tab of the explorer window.

2. Right-click the Terrain Sections folder and select Properties from the context menu. The Terrain Section Properties dialog box appears.

3. Select the Display tab and define the following parameters:

• Under Display Type, select "Value Intervals".

• Under Field, select "Visibility".

• You can change the value intervals and their displayed colour. For information on changing display properties, see

"Setting the Display Properties of Objects" on page 32.

4. Click OK.

5.2.2.2.2 Displaying the Terrain Profile of an Existing Terrain Section

If you have previously calculated a LOS report on a site or a group of sites (see "Analysing the Line of Sight Between Candidate Sites" on page 191), you will already have terrain sections between sites that you can study.

To display the terrain profile of an existing terrain section:

1. On the map, right-click the terrain section you want to analyse. The context menu appears.

2. Select Open Terrain Section. Atoll opens the Terrain Section window.

It displays a Fresnel ellipsoid between both sites, and terrain height and clutter along the profile. In order to calculate the Fresnel ellipsoid, Atoll uses the site heights, the k factor value and the frequency used for the LOS report calcula-tion.

5.2.2.2.3 Creating a Microwave Link with a Terrain Section

You can use a terrain section to create a microwave link.

To create a microwave link from a terrain section:

1. On the map, right-click the terrain section you want to use for a microwave link. The context menu appears.

2. Select Create Link from the context menu. Atoll adds the new microwave link in the Microwave Links folder; its prop-erties are based on the default microwave link template selected in the Microwave Link Planning toolbar.

5.2.2.3 Displaying the Terrain Profile Between Candidate Sites

In Atoll, you can check the terrain profile in the following cases:

• from a site to another site

• from a site to a point on the map

• from a point on the map to a site

• from a point on the map to another point on the map To study the terrain profile between two sites or points on the map:

1. Select how the support height will be defined on both sites of the microwave link by clicking the arrow next to the Terrain Section button ( ) on the toolbar and selecting one of the following:

• Transmitter Heights Defined by Site / Receiver Heights Defined by Site: If you select one of these options, Atoll will use the corresponding support height defined on each site.

• Transmitter Heights Relative to Ground / Receiver Heights Relative to Ground: If you select one of these options, Atoll will use the corresponding support height with respect to ground.

• Transmitter Heights Relative to Clutter / Receiver Heights Relative to Clutter: If you select these options, Atoll will use the corresponding support height with respect to clutter.

• Receiver Height Defined per Clutter Class: If you select this option, Atoll will use the receiver height defined per clutter class on the Clutter tab of the Line of Sight Parameters dialog box.

2. Click the Terrain Section button ( ) on the toolbar.

3. Move the pointer to the site on the map. When the frame appears around the site, indicating it is selected, click to create the first analysis point.

4. Move the pointer to another site on the map. When the frame appears around the site, indicating it is selected, click to create the second analysis point.

A terrain section is created on the map between the sites. The terrain section is coloured according to its visibility (see

"Displaying the Terrain Sections on the Map" on page 192). The profile between both sites appears on the Terrain Section window. The terrain height is displayed along the profile as well as clutter classes and clutter heights. A blue ellipsoid indicates

"Displaying the Terrain Sections on the Map" on page 192). The profile between both sites appears on the Terrain Section window. The terrain height is displayed along the profile as well as clutter classes and clutter heights. A blue ellipsoid indicates

In document Proyecto de estructura de hormigón armado con forjados reticulares para un edificio de uso residencial formado por sótano, planta baja y seis alturas en el municipio de Murcia. (página 165-172)