Introduction to RF Channel Modeler for Communications Analysis

For STK, use any of the following: STK Pro, STK Premium (Air), STK Premium (Space), or STK Enterprise. You also need a separate license for the RF Channel Modeler plugin.
You can obtain the necessary licenses for this tutorial by contacting AGI Support at support@agi.com or 1-800-924-7244.

You must install the RF Channel Modeler plugin separately from the installation of STK. The RF Channel Modeler DVD includes the latest version of STK Pro. If you are downloading the software, the RF Channel Modeler plugin is a separate download from STK. To obtain the RF Channel Modeler download, contact AGI Support at support@agi.com or 1-800-924-7244.

Pictures, graphs, and data snippets are used as examples only. The results of the tutorial may vary depending on the user settings and data enabled (online operations, dynamic Earth data, etc.). It is acceptable to have different results.

Capabilities covered

This lesson covers the following STK capabilities:

• STK Pro
• STK Communications (especially the RF Channel Modeler plugin)

Problem statement

You want to determine the signal connection performance of a base station and its antenna system for a wireless network. You have to account for antenna capability, obscurations, moving transceivers, and signal reflections. You want to see how this base station performs when communicating with a mobile transceiver in the presence of a scene contributor, all against the backdrop of buildings and terrain. This exercise gives you the basic capability to then launch your own further study of varying aspects such as base location, transceiver setup, antenna parameters, scene contributors, etc. The cost is high if you try this using real antennas in real scenes, so you need to simulate this instead.

Solution

You can use STK to model all the objects, facets, and antenna placements in your analysis region. You can then employ the RF Channel Modeler plugin inside of STK to design analysis configurations that include analysis extents, antenna types, waveform settings, transceivers, scene contributors, and reflectance materials. Running each analysis configuration produces an HDF5 file that contains high-fidelity scattering parameter antenna-to-antenna coupling data for all of your analysis configurations. By looking at different types of plots of the data, you can determine the performance of each configuration.

Ultimately, you could enhance this exercise to place your base station at different feasible locations and run more RF Channel Modeler analysis configurations. This would help you to find the optimum location for your base station in that area. For this tutorial, you will just look at one base station location.

For more information on setting up analysis configurations, see the RF Channel Modeler Help.

What you will learn

Upon completion of this tutorial, you will be able to:

• Create a basic STK scenario for a wireless network.
• Load in a facets tileset.
• Set up RF Channel Modeler analysis configurations, including the specification of analysis extents, antenna types, waveform settings, transceivers, scene contributors, and reflectance materials.
• Produce several views of the results of the RF Channel Modeler analysis runs, and see the effects of main antenna and reflected beam interactions.

Learning STK

If you are new to STK, consider first walking through the following Level 1 STK tutorials to become familiar with the basic functionality of STK needed for setting up scenarios for the RF Channel Modeler plugin.

Level 1, Part 1: Build Scenarios

Level 1, Part 2: Objects and Properties

Verifying the RF Channel Modeler plugin is installed

Ensure that the RF Channel Modeler is installed on your computer.

1. Open the STK application (). In the initial dialog box, the RF Channel Modeler should be in the list under "Additional Capabilities".



2. Select the check box next to RF Channel Modeler before continuing. Doing so ensures that the plugin is available within the STK application.

See the next section for how to proceed in STK.

Creating a new scenario

You must create an STK scenario. Then you can set up your RF Channel Modeler analyses. You already launched STK and should now see the Welcome to STK dialog box.

1. Click Create a Scenario.
2. Enter "RFCM" as the Name in the STK: New Scenario Wizard and leave everything else as the default values.
3. Click OK when you finish.
4. Click Save () after the scenario loads. STK creates a folder with the same name as your scenario.
5. Verify the scenario name and location in the Save As dialog box.
6. Click Save.

Save () often during this tutorial!

Enabling your GPU in STK

To run an RF Channel Modeler analysis, you need to let STK know the Graphics Processing Units (GPUs) that you have available on your computer to use. You must have at least one available and registered in STK.

1. Go to the Edit menu in STK and select Preferences.
2. Go to the RF Channel Modeler page.
3. Make sure at least one Enabled check box is selected next to an available GPU on the GPU Properties pane.
4. Click OK to accept any changes and close the Preferences dialog box.

Adding a facets tileset to STK

You need to add a facets tileset to STK that at least covers the area of your analyses. This tileset provides 3D modeling of known stationary structures and terrain in the covered area.

1. Go to the 3D Graphics window.
2. Click the Globe manager icon () in the toolbar.
3. Make sure you are in the Hierarchy tab in the Globe Manager window.
4. Click the Add Terrain/Imagery icon ().
5. Select Add 3D Tilesets.
6. Select the check box next to the AGI_Headquarters tileset.
7. Click Add.
8. Click Yes in the Use Tileset for Analysis dialog box.
9. Close the Globe Manager window.

 

Inserting a Place object

For your analyses, you want to have a network base station transceiver. Create a Place object to anchor the location of the base station transceiver.

1. Click the Insert Object icon ().
2. Select Place () on the left and Define Properties () on the right.
3. Click Insert.... You should see the Basic - Position page of the Place1 properties.
4. Change the following property values:

   Property	Value
   Latitude	40.0389 deg
   Longitude	-75.5963 deg
   Height Above Ground	0.02 km

5. Select the Use terrain data check box.
6. Click OK to apply and close the properties.

You now have a base at about 65 feet above the terrain.

Inserting a Sensor object for Place1

Add a sensor and attach it to Place1. You must have a Sensor object in STK as the host for any transceiver in the RF Channel Modeler.

1. Click the Insert Object icon ().
2. Select to insert a Sensor () object using the Define Properties () method.
3. Click Insert.
4. Attach the sensor to Place1 in the Select Object dialog box.
5. Click OK. The Basic - Definition page of the Sensor1 properties should appear.
6. Set Cone Half Angle to 10 degrees.
7. Go to the Basic - Pointing page.
8. Set Azimuth to 0 degrees and Elevation to 90 degrees, so the sensor is pointing directly up.
9. Click OK to apply and close the properties.

Inserting a Ground Vehicle object

You will add a moving transceiver to your analyses. Create a Ground Vehicle object to carry the transceiver and generate the motion using four waypoints that define the span of the analysis interval.

1. Click the Insert Object icon ().
2. Select to insert a Ground Vehicle () object using the Define Properties () method.
3. Click Insert. The Basic - Route page of the GroundVehicle1 properties should appear.

Creating waypoints

Someone is driving GroundVehicle1 () near Place1 (). You can define its course using the Basic - Route properties page. You will assign four waypoints, specifying latitude, longitude, and altitude for each. You do not need to set Speed, Accel, Time, or Turn Radius; just accept the default values for these.

1. Click Insert Point on the Basic - Route page of GroundVehicle1's properties.
2. Set the following for the first waypoint:

Option	Value
Latitude	40.03822 deg
Longitude	-75.59748 deg
Altitude	0.00675 km

3. Click Insert Point.
4. Set the following for the second waypoint:

Option	Value
Latitude	40.0392 deg
Longitude	-75.5982 deg
Altitude	0.00597 km

5. Click Insert Point.
6. Set the following for the third waypoint:

Option	Value
Latitude	40.03976 deg
Longitude	-75.5968 deg
Altitude	0.00599 km

7. Click Insert Point.
8. Set the following for the fourth waypoint:

Option	Value
Latitude	40.03857 deg
Longitude	-75.59596 deg
Altitude	0.00823 km

9. Set Reference to Terrain in the Altitude Reference section of the page.
10. Click OK to accept all changes and close the GroundVehicle1 Properties Browser.

Keep in mind that the center point of the ground vehicle is right on top of the terrain. The object center point, unless changed, is where analysis for the object takes place. Also, terrain undulation could be a factor. The ground vehicle could appear, visually, to dart into and out of terrain, especially when modeling in an area containing rugged terrain. Terrain resolution can be a factor too.

All ground object center points start on the terrain surface.

Inserting a Sensor object for GroundVehicle1

Add a sensor and attach it to GroundVehicle1. This serves as the host for the mobile transceiver.

1. Click the Insert Object icon ().
2. Select to insert a Sensor () object using the Define Properties () method.
3. Click Insert.
4. Attach the sensor to GroundVehicle1 in the Select Object dialog box.
5. Click OK. The Basic - Definition page of the Sensor2 properties should appear.
6. Set Cone Half Angle to 45 degrees.
7. Go to the Basic - Pointing page.
8. Set Azimuth to 0 degrees and Elevation to 90 degrees.
9. Click OK to apply and close the properties.

Creating a Facility object as a scene contributor

Create a facility of sufficient size to use as an RF Channel Modeler scene contributor that will tangibly influence analysis results. In the 3D Graphics window, the facility will look like a cube.

1. Click the Insert Object icon ().
2. Select Facility () on the left and Define Properties () on the right.
3. Click Insert.... You should see the Basic - Position page of the Facility1 properties.
4. Change the following property values:

   Property	Value
   Latitude	40.0395 deg
   Longitude	-75.5963 deg
   Height Above Ground	0 km

5. Select the Use terrain data check box, if not already selected.
6. Go to the 3D Graphics - Model page.
7. Click the ellipsis () next to Model File and browse to and select the Cube.glb file in your install folder at C:\Program Files\AGI\STK 12\Data\Resources\stktraining\samples. This is a cube-shaped building model.
8. Click OK to apply and close the properties.
9. Click Facility1 in the STK Object Browser, right-click, and select Zoom To. In the 3D Grapics window, you can see that Facility1 is very close to Place1, your base station. Ground Vehicle1 will pass between Place1 and Facility1 near the end of its route.

Opening the RF Channel Modeler plugin

You are now ready to use the RF Channel Modeler plugin to analyze your scenario. You will not need the Timeline View area, so delete it to create more space for viewing the plugin UI.

1. Click the deletion "X" near the bottom of the STK UI to delete the Timeline View section.
2. Click the Utilities menu in STK.
3. Select RF Channel Modeler.

You will work in this plugin UI for the remainder of the tutorial.

Adding transceivers

Under the Design tab of the RF Channel Modeler, you will now add transceivers to both sensors in the STK scenario. The transceivers will not appear as STK objects in the STK Object Browser. For each transceiver, you will specify (or accept default) parameters for the transceiver antenna, waveform, and the STK 3D Graphics window display.

Make sure you are working in the Design tab of the RF Channel Modeler before proceeding. The Design tab should list the Place, Ground Vehicle, and Sensor objects in the Object Browser of STK.

Adding a transceiver to Sensor1 on Place1

1. Expand () Place1 in the Design tab.
2. Select Sensor1 and click the down arrow next the Add Transceiver icon () to select Communications type. This creates a Communications transceiver () called Sensor1_TxRx.
3. Click OK in the Add Communications Transceiver dialog box that appears.
4. Expand () Sensor1_TxRx, if necessary, and select Antenna.
5. Set the following Antenna parameters:

   Parameter	Value
   Antenna Type	Far Field Data Pattern
   HFSS Element Export Pattern File	Click Select and choose "3.5GHz_DipoleV.ffd" in your install folder at C:\Program Files\AGI\STK 12\Data\Resources\stktraining\samples.

6. Select Waveform and apply the following parameter values:

   Parameter	Value
   RF Channel Frequency (GHz)	3.5
   Channel Bandwidth (MHz)	100
   Frequency Samples / Sounding	512
   Sounding Interval (msec)	20
   Soundings / Analysis Time Step	10
   Complete Simulation Interval (msec)	Read only
   Unambiguous Channel Delay (msec)	Read only
   Unambiguous Channel Distance (m)	Read only

7. Select Graphics and apply the following parameter values:

   Parameter	Value
   Show Sensor Body Axes	Do not select this check box.
   Enable	Select this check box.
   Max Radius (m)	5
   Display Range (dB)	Select the Auto check box.

 

Adding a transceiver to Sensor2 on GroundVehicle1

1. Expand () GroundVehicle1 and Sensor2 in the Design tab.
2. Select Sensor2 and click the down arrow next the Add Transceiver icon () to select Communications type. This creates a Communications transceiver () called Sensor2_TxRx.
3. Click OK in the Add Communications Transceiver dialog box that appears.
4. Expand () Sensor2_TxRx and select Antenna.
5. Set the following Antenna parameters:

   Parameter	Value
   Antenna Type	Far Field Data Pattern
   HFSS Element Export Pattern File	Click Select and choose "3.5GHz_DipoleV.ffd" in your install folder at C:\Program Files\AGI\STK 12\Data\Resources\stktraining\samples.

6. Select Waveform and apply the following parameter values:

   Parameter	Value
   RF Channel Frequency (GHz)	3.5
   Channel Bandwidth (MHz)	100
   Frequency Samples / Sounding	512
   Sounding Interval (msec)	20
   Soundings / Analysis Time Step	10
   Complete Simulation Interval (msec)	Read only
   Unambiguous Channel Delay (msec)	Read only
   Unambiguous Channel Distance (m)	Read only

7. Select Graphics and apply the following parameter values:

   Parameter	Value
   Show Sensor Body Axes	Do not select this check box.
   Enable	Select this check box.
   Max Radius (m)	5
   Display Range (dB)	Select the Auto check box.

Your Design tab should look like this:

Creating analysis configurations

In the Analysis tab in the RF Channel Modeler, you can create analysis configurations and apply whichever transceivers you wish from the ones you created under the Design tab. You need to add a facet tileset to each analysis configuration. You can add scene contributors from the list of qualifying objects in the STK Object Browser. Adding a scene contributors places a custom item in the analysis that can cause signal reflections, in addition to the reflections from existing objects and terrain in the facets tileset. The RF Channel Modeler will check to assure that any scene contributor object you select has an associated model that provides suface facets, otherwise the analysis computation will fail. The Analysis tab also enables you to specify analysis compute times and designate the results file mode and output folder path. You can then run an analysis configuration from the Analysis tab.

For this section, make sure you are in the Analysis tab of the RF Channel Modeler. You will create two analysis configurations by setting up one and then copying and modifying the copy to generate a second.

Creating an analysis configuration

Create an analysis configuration, which you will specify in the following sections.

1. Click the down arrow next to the Add Configuration icon () at the upper-left corner of the Analysis tab.
2. Select "Communications". The Add Communications Configuration dialog box appears.
3. Enter the name "Mobile_Only" in the Add Communications Configuration dialog box.
4. Click OK.

You now have an analysis configuration available to set up and compute. For Mobile_Only, you will not add any scene contributors.

Choosing transceivers for the analysis configuration

For Mobile_Only, choose the transceivers on Place1 and GroundVehicle1.

1. Select Mobile_Only at the top of the Analysis tab.
2. Click the Add Transceiver Configuration icon () in the Transceivers subtab below. The Add Communications Analysis Configuration Transceivers dialog box will appear.
3. Select the Select check boxes for the following transceivers in the Add Analysis Configuration Transceivers dialog box:
   • Sensor1_TxRx
   • Sensor2_TxRx
4. Click OK.
5. Set the Mode to TransmitOnly for Sensor1_TxRx.
6. Set the Mode to ReceiveOnly for Sensor2_TxRx.

Setting the analysis compute times

Enter specific start and stop times for your analysis. Although the STK scenario covers an entire day, you want to greatly reduce the actual analysis time span due to the significant amount of time it takes to process even a minute or two of a configuration. Since GroundVehicle1 is part of the analysis configuration and only has waypoints to cover about 15.2 seconds of scenario time, the analysis would stop after 15+ seconds. However, you should set the analysis time to make sure that alterations to the configuration do not lengthen the analysis computation time to excessive durations.

You can see the duration of waypoint availability by opening the properties of GroundVehicle1 in the STK Object Browser and looking at the Basic - Route page. For the last waypoint, the Time will show how long the vehicle took to go from the starting waypoint to that ending waypoint.

1. Select Mobile_Only at the top of the Analysis tab.
2. Go to the Analysis Compute Times subtab.
3. Clear the Use Scenario Analysis Interval check box, if necessary.
4. Enter 0.000 (EpSec) for Start Time.
5. Enter 16.000 (EpSec) for Stop Time.
6. Select the Continuous Channel Soundings radio button, if not already selected..

Choosing a facet tileset

Apply the AGI_Headquarters facet tileset to this analysis configuration.

1. Select Mobile_Only at the top of the Analysis tab.
2. Go to the Facet Tileset subtab.
3. Highlight the AGI_Headquarters tileset in the Available Tilesets pane. You might need to scroll down the subtab to see the pane.
4. Click >> to move AGI_Headquarters to the Selected Tilesets list.
5. Click the drop-down arrow under Material and select Asphalt. This is a realistic tileset material designation for the scenario.

Setting analysis extents

Use the Analysis Extent Tool to create a bounded area inside the AGI-Headquarters facet tileset region. The tool enables you to set the northwest and southeast corners.

When you run your analysis, the GPU-SBR+ Solver will only consider objects (stationary and moving) within the extents you set here, not all objects in the entire facet tileset region.

1. Select Mobile_Only at the top of the Analysis tab.
2. Make sure you are still in the Facet Tileset subtab.
3. Click Launch Extent Tool.
4. Enter the following values in the Analysis Extent Tool dialog box:

   Extent parameter	Value
   Northwest Latitude (deg)	40.04013
   Northwest Longitude (deg)	-75.59884
   Southeast Latitude (deg)	40.03788
   Southeast Longitude (deg)	-75.59514

5. Click Apply to save the values and close the dialog box.
6. Select the Show Extent check box in the Analysis Extent Graphics pane. Keep the default settings for the other parameters.
7. Minimize the RF Channel Modeler window and look at your 3D Graphics window in STK. You should be able to see the extents box inside of the tileset. The box should enclose the vehicle path, buildings, facility, and most of the parking area.

Setting the results output

Set the results file mode and the output folder.

1. Go to the Results Output subtab.
2. Click Edit at the bottom of the Analysis Description pane.
3. Write the following sentence in the Analysis Description box: "Configuration 1: Vehicle 1 is moving in the area of the AGI Headquarters in the presence of the Place1 transceiver. There are no scene contributors."
4. Click OK to close the Analysis Description dialog box.
5. Set Results File Mode to Single file if not already set.
6. Look at the bottom of the Analysis tab and make note of the default results folder that the RF Channel modeler will create for you when you start generating output.

Look near the top of the RF Channel Modeler window. Your Mobile_Only analysis configuration should have a status of "Ready to run."

Creating a second analysis configuration

You will create a second analysis configuration by copying the first. This second configuration will be the same as the first, with the difference being the addition of Facility1 as a scene contributor.

1. Select Mobile_Only at the top of the Analysis tab.
2. Click the Duplicate Configuration icon ().
3. Enter "Mobile_and_Facility" as the Name in the Duplicate Configurations Analysis dialog box.
4. Click OK to close the dialog box.

Adding a scene contributor to Mobile_and_Facility

For the Mobile_and_Facility analysis configuration, you will add Facility1 as a scene contributor.

1. Select the Mobile_and_Facility analysis configuration at the top of the Analysis tab.
2. Go to the Scene Contributor Objects subtab.
3. Click the Add Scene Contributor icon ().
4. Select the Select check box for Facility1 in the Add Analysis Configuration Scene Contributors dialog box.
5. Click OK.
6. Make sure "Metal" is the material named in the Material column.

Adjusting the description for Mobile_and_Facility

1. Click the Results Output subtab.
2. Click Edit.
3. Change the Analysis Description box entry to the following: "Configuration 2: Vehicle 1 is moving in the area of AGI Headquarters in the presence of the Place1 transceiver. Facility 1 is a scene contributor with metal construction."
4. Click OK to close the Analysis Description dialog box.

Generating results

Run both analysis configurations to see the resulting data for the 16-second interval.

1. Select Mobile_Only at the top of the Analysis tab.
2. Click Run Analysis at the bottom of the Analysis tab.
3. Repeat steps 1-2 for Mobile_and_Facility.

The results are now in the output folder.

Viewing results from analysis runs

The Results tab enables you to filter for specific data and view different plot types within the analysis runs you already generated. Based on your selection of Analysis (analysis configuration), Results (time stamp), and Link (transceiver connection), the Summary section provides a read-only view of key parameter values. You can use the Plotting Parameters section to choose the plot type and its accompanying parameter values.

After you generate the plot, the right side of the Results tab shows the specific plot. You can then alter the display view (lines, colors, symbols, zoom, etc.), and you have other options available such as save, copy, print, etc.

Plotting Response vs Frequency from the Mobile_Only run results

Generate and view a Response vs Frequency plot of the data from running Mobile_Only.

1. Select the Results tab at the top of the RF Channel Modeler UI.
2. Select the Use analysis output folder as results folder check box, if not already selected, near the top of the Results tab. This tells the RF Channel Modeler to automatically point to the output folder specified in the Analysis tab.
3. Select Mobile_Only for Analysis in the Results Filter section.
4. There should be only one choice for Results.
5. For Link, select Place1-Sensor1-Sensor1_TxRx_to_GroundVehicle1-Sensor2-Sensor2_TxRx.
6. Set the following under Plotting Parameters:

   Extent parameter	Value
   Plot Type	Response vs Frequency
   Transmit Antenna Index	0
   Receive Antenna Index	0
   Channel Sounding Index	0
   Time Sample (EpSec)	4

7. Click Generate Plot.

Viewing the plot display

You can see your selected plot of data on the right. Try out some different ways to view the data.

1. Click the Display Plot Data icon () at the top to show a split screen of the plot and the underlying data. This toggle is not available for waterfall plots because the amount of data is too great.
2. Click again to see just the plot.
3. Right-click the plot and try out the different line, color, symbol, grid and legend settings.
4. Scroll the middle button of your mouse forward to zoom in and out on the plot.
5. Choose an area to zoom in on by holding the left mouse button down and dragging a box around the area to highlight. You should see a closer view of just the boxed area.
6. Go back to the original plot by right-clicking and selecting Undo Zoom.

Viewing the Time vs Frequency Waterfall plot for Mobile_Only

Plots like "Response vs Frequency" and "Response vs Time" give insight for a specific time and frequency, respectively. However, you want to get a broader picture of what is happening in the scenario over the whole time period for a range of frequencies. For this broader view, use waterfall plots. The first one to try is Time vs Frequency Waterfall.

1. Set the following under Plotting Parameters:

   Extent parameter	Value
   Plot Type	Time vs Frequency Waterfall
   Transmit Antenna Index	0
   Receive Antenna Index	0
   Channel Sounding Index	0

2. Click Generate Plot.
3. You will see that, except for a few specific times, the signal strength is weak across all frequencies for the first 11 seconds or so, which is the lower three-fourths of the plot. This is because the buildings are generally blocking the direct line of sight from the Place antenna to the Ground Vehicle antenna. When the Ground Vehicle is in view, the signal strength goes up, as expected.

   

4. Place your cursor over the plot and right-click.
5. Select Decibel from the shortcut list. This changes the plot to a decibel scale, as you can see in the legend on the right.

   

Viewing the Time vs Signal Distance-of-Flight Waterfall plot for Mobile_Only

Now try the Time vs Signal Distance-of-Flight Waterfall plot. This shows the distance traveled by the signal, revealing the direct connection between the Place antenna and the Ground Vehicle antenna as well as the reflected signals.

1. Set the following under Plotting Parameters:

   Extent parameter	Value
   Plot Type	Time vs Signal Distance-of-Flight Waterfall
   Transmit Antenna Index	0
   Receive Antenna Index	0
   Channel Sounding Index	0

2. Click Generate Plot. The plot will be in Decibel scale, since you did not change that setting.
3. The signals of interest are all on the left quarter of the plot, so try to enlarge that area. Click and hold a point on the plot just in the upper-left corner, and then drag the cursor down and to the right to cover just the areas that have some contrast, at about 400 m. When you let go of the left-click button, the plot will refocus to just the area that you outlined.

You will see the main signal path. The two changes in trajectory at about 4.5 and 9.5 seconds represent the vehicle turning corners. After the second corner, the main signal forms essentially a parabolic path as the vehicle makes its closest approach to the Place antenna around the 12.5 second mark and then starts moving away. The lighter signals to the right of the main path represent reflections off of buildings and other tileset items.

Viewing the results for Mobile_and_Facility

Now generate the results from the Mobile_and_Facility analysis configuration. This time, go directly to the Time vs Signal Distance-of-Flight Waterfall plot. You want to see the effect the scene contributor (Facility1) has on the results.

1. Select the Use analysis output folder as results folder check box near the top of the Results tab.
2. Select Mobile_and_Facility for Analysis in the Results Filter section.
3. There should be only one choice for Results.
4. For Link, select Place1-Sensor1-Sensor1_TxRx_to_GroundVehicle1-Sensor2-Sensor2_TxRx.
5. Set the following under Plotting Parameters:

   Extent parameter	Value
   Plot Type	Time vs Signal Distance-of-Flight Waterfall
   Transmit Antenna Index	0
   Receive Antenna Index	0
   Channel Sounding Index	0

6. Click Generate Plot.
7. The signals of interest are all on the left quarter of the plot, so try to enlarge that area. Click and hold a point on the plot just in the upper-left corner, and then drag the cursor down and to the right to cover just the areas that have some contrast, at about 400 m. When you let go of the left-click button, the plot will refocus to just the area that you outlined.

Again, you see the main signal path on the plot. However, this time the reflected signals to the right of the main signal path are different, particularly in the last few seconds (at the top). The vehicle is directly between the Place antenna and the Facility scene contributor at about 13.5 EpSec. Starting at about 12 EpSec, you can see a secondary line starting at the 70 m mark and slanting up and right. This is a secondary signal from the Facility (scene contributor) that was not present in the Time vs Signal Distance of Flight waterfall plot for Mobile_Only.

Changing the scene contributor shape

You can use a different model (building shape)for Facility1 and see what the impact is on your results.

1. Highlight Facility1 in the STK Object Browser and click the Properties icon ().
2. Go to the 3D Graphics - Model page.
3. Click the ellipsis () for Model File.
4. Go to C:\Program Files\AGI\STK 12\STKData\VO\Models\Land and choose the facility.glb file. In the 3D Graphics window, you can see that this facility model is shaped like a golf ball.
5. Click OK to apply the changes and close the Properties Browser.
6. Go back to the RF Channel Modeler Analysis tab and rerun the Mobile_and_Facility analysis configuration.
7. Go to the Results tab.
8. Select the latest Mobile_and_Facility results.
9. Click Generate Plot for Plot Type = Time vs Signal Distance-of-Flight Waterfall.

Notice that the secondary signal line coming from the Facility1 scene contributor is weaker and more spread out because the amount of reflectance off the ball shape is lower and more scattered than the reflectance off the side of the cube.

Save your work

1. Close any reports, graphs, or tools that remain open.
2. Save () your work.

Conclusion

In this exercise, you learned how to use STK and the RF Channel Modeler plugin to do the following:

• Place a base station, model a moving object, and create a stationary facility in STK
• Place sensor objects on STK objects
• Use RF Channel Modeler to add transceivers to sensor objects and apply specific antenna types, waveforms, and graphics properties to the transceivers
• Designate transceivers for analysis configurations
• Include local structures, terrain, and scene contributors in the analysis
• Specify analysis extents
• Generate different plot types to visualize your results data

You saw that a scene contributor can significantly affect your results.

On your own

In this lesson, you set up and ran two analysis configurations, with the only variation being a scene contributor. Take the time to explore possible variations by changing the antenna placements and types, the waveform settings, and the scene contributor objects and characteristics.

You can also explore using STK's Connect commanding capability to perform both the STK scenario setup and the RF Channel Modeler analysis configuring and execution. To do this, you should first complete the STK general tutorial on Connect commanding:

Level 1, Part 5: Introduction to Connect

This will help you on your way toward building the STK scenario. You can then set up and run RF Channel Modeler analysis configurations, perform the runs, and retrieve the results. Use the following Help pages to guide your building of the RF Channel Modeler commanding:

RfChannelModeler - These are the basic commands for setting up and running analysis configurations.

RfChannelModeler_RM - Use these commands to retrieve information from the RF Channel Modeler.

RfChannelModelerGraphics - Use this command to set values for graphics quantities such as antenna boundaries and analysis extents.

RfChannelModelerGraphics_RM - Use this command to retrieve values for graphics attributes.