Will Terrain Obstruct My Ability to Detect a Low-Flying Airborne Platform?
STK Pro, STK Premium (Air), STK Premium (Space), or STK Enterprise
You can obtain the necessary licenses for this tutorial by contacting AGI Support at support@agi.com or 1-800-924-7244.
This tutorial requires STK 12.9 or newer to complete in its entirety. If you have an earlier version of STK, you can view a legacy version of this lesson.
The results of the tutorial may vary depending on the user settings and data enabled (online operations, terrain server, dynamic Earth data, etc.). It is acceptable to have different results.
Capabilities covered
This lesson covers the following STK Capabilities:
- STK Pro
Problem statement
You require a fast and easy way to simulate and test a mobile tracking radar in the Pacific Northwest region of the United States. The planned location is in very mountainous terrain. Technicians are manning the main radar site also known as base camp. Another team of technicians will fly a drone towards the base camp. Technicians at the base camp have access to the drone's flight data. You are working with the base camp team and you need to determine if the current radar location provides ample warning of the drone based on terrain, line of sight, and field of view. You have two additional mobile tracking radars that can be used in the test. Should you consider extending your perimeter by setting up the additional radars in a selected, confined area?
Solution
In this exercise, you will use STK to define and assess a complex, practice scenario, and then model and analyze that problem. You will build an STK scenario that will help you determine the placement of the mobile tracking radars that can search for and track a drone that is headed towards base camp. You will use STK Pro and a terrain file of the area to determine if you can detect the drone using the current radar system's specified field of view, and assess whether additional radar locations would strengthen the system and provide the access coverage that you require.
What you will learn
Upon completion, you will have had the opportunity to practice the following skills:
- Use a local terrain file (*.pdtt) for analysis and visualization.
- Create azimuth-elevation masks.
- Create a custom report.
- Import a previously constructed aircraft ephemeris file to model the drone's flight.
- Assess the feasibility of using your current radar system's location using Place and Sensor objects to detect a low-flying airborne platform.
Creating a new scenario
First, you must create a new STK scenario.
- Launch STK ().
- Click in the Welcome to STK dialog box.
- Enter the following in the STK: New Scenario Wizard:
- Click when you finish.
- Click Save () after the scenario loads. STK creates a folder with the same name as your scenario for you.
- Verify the scenario name and location in the Save As dialog box.
Option | Value |
---|---|
Name | Drone_Detection |
Start | 1 Dec 2023 19:00:00.000 UTCG |
Stop | + 10 min |
Save ( ) often during this lesson!
Turning off STK Terrain Server
Since you'll use a local terrain file for analysis and visualization, turn off STK Terrain Server.
- Right-click Drone_Detection ( ) in the Object Browser.
- Select Properties ( ) in the shortcut menu.
- Select the Basic – Terrain page when the Properties Browser opens.
- Clear Use terrain server for analysis.
- Click to accept your change and to close the Properties Browser.
Turning on a local terrain file
The Pro capability adds realism to system models. Pro introduces more sophisticated modeling through advanced access constraints, flexible sensor shapes, complex visibility links, more object tracks and digital terrain data. Microsoft Bing Maps can be used for imagery. However, imagery is not required.
- Bring the 3D Graphics window to the front.
- Click Globe Manager () in the Globe Manager toolbar.
- Click Add Terrain/Imagery () in the Globe Manager toolbar.
- Select Add Terrain/Imagery... () in the shortcut menu.
- Click the Path ellipsis () in the Globe Manager: Open Terrain and Imagery Data.
- Navigate to <STK Install Folder>\Data\Resources\stktraining\imagery> in the Select Image Directory when the Browse For Folder opens.
- Click .
- Select the StHelens_Training.pdtt check box.
- Click .
- Click when prompted to Use Terrain for Analysis.
Decluttering 3D Graphics window labels
Label Declutter is used to separate the labels on objects that are in close proximity for better identification in small areas.
- Bring the 3D Graphics window to the front.
- Click Properties () in the 3D Windows toolbar.
- Select the Details page.
- Select Enable in the Label Declutter frame.
- Click .
This will make it easier to see the object labels in the 3D Graphics window.
Break it down
Prior to simulating your scenario, you should understand the following:
-
The base camp tracking radar is located in mountainous terrain and is not mobile.
-
The drone team will launch a drone towards the base camp.
-
The drone will employ terrain following with a programmed altitude of 200 meters AGL (height above ground level) and a cruise speed of approximately 500 miles per hour.
-
All mobile radar tracking vehicles must use available roads to include little-used dirt roads.
-
Base camp personnel require a minimum of two minutes of tracking time for the mission to be a success.
Creating a base camp radar site
Use a Place () object to simulate the fixed in place radar at base camp.
- Select Place () in the Insert STK Objects tool.
- Select the Define Properties ( ) method.
- Click .
- Select the Basic - Position page when the Properties Browser opens.
- Set the following in the Position frame:
- Click to accept your changes and to keep the Properties Browser open.
- Right-click Place1 () in the Object Browser.
- Select Rename in the shortcut menu.
- Rename Place1 () to Main_Radar.
Option | Value |
---|---|
Latitude: | 46.2927 deg |
Longitude: | -122.271 deg |
Height Above Ground: | 10 ft |
Setting Height Above Ground to 10 feet simulates the antenna height on the vehicle.
Defining an azimuth-elevation mask
The AzElMask properties enable you to define an azimuth-elevation mask for the radar site.
- Select the Basic - AzElMask page.
- Set the following:
Option Value Use: Terrain Data Use Mask for Access Constraint on - Click .
Constraining the radar site's field of view
Base camp radar is able to track aircraft out to a range of fifty (50) kilometers. You are doing a quick analysis on how the terrain might affect the radar site's field of view, so set the max range constraint to 50 km.
- Select the Constraints - Active page.
- Click Add new constraints () in the Active Constraints toolbar.
- Select Range in the Constraint Name list in the Select Constraints to Add dialog box.
- Click .
- Click to close the Select Constraints to Add dialog box.
- Select the Max: check box in the Range frame.
- Enter 50 km in the Max: field.
- Click .
Range is measured as the distance between the two objects, in this case between the Place () object and the cruise missile. Az-El Mask was added to the Active Constraints list when you turned on the Mask for Access Constraint option in the previous section. The other constraint that is being used is Line of Sight. For a Place () object, Line of Sight models the ground as the ellipsoid passing through its ground position with the same surface normal vector as that of its central body ellipsoid shape. A facility, place, or target configured with nonzero height above ground may look downward from that height to its ground model.
Displaying the azimuth-elevation mask
For situational awareness, you can visualize the azimuth-elevation mask in both the 2D Graphics and 3D Graphics windows.
- Select the 2D Graphics - AzElMask page.
- Select Show in the At Range frame.
- Set the following:
- Click to accept your changes and to close the Properties Browser.
Option | Value |
---|---|
Number of Steps: | 5 |
Minimum Range: | 0 km |
Maximum Range: | 50 km |
Viewing the radar site in the 3D Graphics window
You can see the visual depiction of the radar's field of view in the 3D Graphics window.
- Bring the 3D Graphics window to the front.
- Right-click Main_Radar () in the Object Browser.
- Select Zoom To in the shortcut menu.
- Using your mouse, zoom out until you can see the visual representation of the Azimuth-Elevation Mask.
Main Radar Site Azimuth-Elevation Mask
Each ring represents a ten (10) kilometer range out to fifty (50) kilometers. Around the edge of the view, you can see indications of north (N), south (S), east (E), and west (W). The radar's field of view is poor to the north, east, and southeast.
Enhancing situational awareness with sensors
The visual azimuth-elevation mask for the Place () object gives you a good bottom field of view. Using a Sensor () object can enhance this view by giving you a complete 3D Graphics representation in all directions (X, Y, Z). Analytically it's not required, but visually it'll win you points in a briefing. However, you can use the Sensor () object analytically. Both the Sensor () object and Place () object "see" the same thing. They simply provide different graphical representations.
You need a sensor that covers 360 degrees (basically a round bubble). You will use a Complex Conic sensor. Complex Conic sensor patterns are defined by the inner and outer half angles (vertical) and minimum and maximum clock angles (horizontal) of the sensor's cone.
- Insert a Sensor () object using the Define Properties () method.
- Select Main_Radar () in the Select Object dialog box.
- Click .
- Select the Basic - Definition page in the Properties Browser.
- Set the following:
Option Value Sensor Type Complex Conic Outer - Half Angles 180 deg - Click .
- Rename Sensor1 () to Main_RadarFOV.
Applying the analytical terrain constraint
Since the Sensor () object is subordinate to Main_Radar(), you simply "borrow" Main_Radar's () azimuth-elevation mask and apply it to the Sensor () object.
- Select the Constraints - Active page.
- Click Add new constraints () in the Active Constraints toolbar.
- Select Az-El Mask in the Constraint Name list in the Select Constraints to Add dialog box.
- Click .
- Click to close the Select Constraints to Add dialog box.
Applying the range constraint
Set the Sensor's () max range constraint to 50 km.
- Return to the the Constraints - Active page.
- Click Add new constraints () in the Active Constraints toolbar.
- Select Range in the Constraint Name list in the Select Constraints to Add dialog box.
- Click .
- Click to close the Select Constraints to Add dialog box.
- Select the Max: check box in the Range frame.
- Enter 50 km in the Max: field.
- Click .
Visualizing the Constraints
The Sensor () object is set up analytically. In order to see the constraints, instruct STK to apply them visually.
- Select the 2D Graphics - Projection page.
- Select Use Constraints in the Field of View frame.
- Select AzElMask in the list of constraints.
- Click .
- Select the 3D Graphics - Attributes page.
- Enter 50 in the % Translucency field in the Projection frame.
- Click to accept your changes and to close the Properties Browser.
In STK, making changes to an object's 2D Graphics properties applies the visual changes to both the 2D Graphics and 3D Graphics windows. If you make changes to 3D Graphics properties, they are only applied to the 3D Graphics window.
The "bottom" of the Sensor object conforms to the visual azimuth-elevation mask of Main_Radar. Increasing translucency makes it easier to see through the visual representation of both objects.
Viewing the combined sensor and place fields-of-view in the 3D Graphics window
- Bring the 3D Graphics window to the front.
- Zoom to Main_Radar().
- Using your mouse, zoom out until you can see the visual representation of the Azimuth-Elevation Mask for both the Place () object and the Sensor () object.
Place Object and Sensor Object Situational Awareness
Creating STK ephemeris files
Throughout the exercise, there is a possibility that the drone team may launch drones from different directions. As this data is obtained, you would like to create external ephemeris files that can be quickly used depending on which flight route has been programmed into a particular drone.
The StkExternal Propagator enables you to import the ephemeris for a vehicle directly from a file. You can create vehicle attitude or ephemeris data for all types of vehicles using the Export Ephemeris/Attitude tool. Basically, you create a flight route for an aircraft, export the flight route as an STK Ephemeris file, and save the file. Whenever that flight route is used, you can quickly import the ephemeris data back into STK.
Import a previously constructed Aircraft () object ephemeris file in order to quickly build the drone's flight route.
Importing the drone's flight route
The drone will employ terrain following with a programmed altitude of 200 meters AGL and a cruise speed of approximately 500 miles per hour. You have an ephemeris file containing the flight path of the drone. Apply the ephemeris file to an Aircraft () object to simulate the drone's flight path.
- Insert an Aircraft () object using the Define Properties () method.
- Select the Basic - Route page when the Properties Browser opens.
- Open the Propagator drop-down menu.
- Select StkExternal.
- Click the Filename: ellipsis ().
- Go to <STK Install Folder>\Data\Resources\stktraining\samples>.
- Select Missile_Route.e.
- Click .
- Select the Override the times contained in the file check box.
- Click to accept your changes and close the Properties Browser.
- Rename the Aircraft1 () to Drone.
When an ephemeris file is created during a different time period, pay attention to Overide the times contained in the file. This enables you to specify the time of the first ephemeris point to your current scenario time period. To limit the span of external ephemeris available for analysis, select Limit ephemeris for analysis to the Scenario Interval. The ephemeris file was created on 1 Dec 2018. Your scenario is taking place on a different date.
Change your perspective
- Bring the 3D Graphics window to the front.
- Zoom to Drone ().
drone with Default Model
Using a realistic aircraft model
Drone () is using the generic, default aircraft model (aircraft.glb). Change it to an STK model that mimics a drone.
- Open Drone's () properties ().
- Select the 3D Graphics - Model page when the Properties Browser opens.
- Click the Model File ellipsis () in the Model frame.
- Select uav.glb when the File dialog box opens.
- Click .
- Click to accept your change and to keep the Properties Browser open.
- Bring the 3D Graphics window to the front.
drone with New Model
Adding drop lines
To further enhance situational awareness and enhance visuals that can be used in a briefing, you can better visualize your flight route, following the terrain, as it travels along its trajectory using drop lines. Prior to including drop lines, you'll change the appearance of the air track.
- Return to Drone's () properties ().
- Select the 2D Graphics - Attributes page.
- Select white in the Color drop-down menu
- Select the line with maximum thickness in the Line Width drop-down menu.
- Click to accept your changes and to keep the Properties Browser open.
- Select the 3D Graphics - Droplines page.
- Set the following Terrain options in the From Route frame:
- Click to accept your changes and to close the Properties Browser.
- Bring the 3D Graphics window to the front.
- Use your mouse to arrange the 3D Graphic window so that you can see Drone's () flight route.
Option | Value |
---|---|
Show | Select the check box |
Interval | 1.0 sec |
drone's Drop Lines
Tracking the drone
Main_Radar () appears to have poor visibility in multiple directions. Take a look at Main_Radar () to obtain situational awareness on which direction Drone () is coming from.
- Bring the 3D Graphics window to the front.
- Open the 3D Graphics window's properties ().
- Select the Annotation page when the Properties Browser opens.
- Set the following in the Compass frame:
- Click to accept your changes and to close the Properties Browser.
- Zoom to Main_Radar().
- Mouse around in the 3D Graphics window to get a better view of Main_Radar() and Drone ().
Option | Value |
---|---|
Show | Select the check box |
Y Origin | Top |
Radius | 80 |
Main Radar and drone Comparison
The compass is located in the upper left corner of the 3D Graphics window. The drone appears to be coming from a northerly direction, and it appears that the main radar can see it, but for how long?
Generating an access report
Your visualizations are complete. It's time to do some analysis. If you recall, base camp requires a minimum of two minutes of tracking time for a successful test. Also, the drone is flying at a speed of 500 miles per hour. Use the Access Tool to determine what time you begin tracking the drone, for how long, and other pertinent data such as azimuth, elevation, and range, which are used for tracking purposes.
- Right-click Main_Radar() in the Object Browser.
- Select Access... () in the shortcut menu.
- Select Drone () in the Associated Objects list when the Access Tool opens.
- Click .
- Click in the Reports frame.
- Close the Access report.
Does base camp have the required two (2) minutes to track the drone?
Determining the drone location
You are using STK to make a preliminary analysis of whether or not your radar system can track the drone. The analysis is solely based on a radar system's reported field of view (system specifications) due to the central body, in this case the Earth, and terrain. The access report shows that the radar will track the drone for approximately eight (8) seconds prior reaching the base camp. From which azimuth, elevation, and range does the system first pick up the drone?
- Return to the Access Tool.
- Click the Reports frame.
- Use the AER report to answer the following questions:
- How close to Main_Radar() is Drone () when it can first be tracked?
- Based on this data, will you require more radar sites to possibly help tracking the drone for the required two (2) minutes?
- Close the report and the Access Tool.
Extend your radar coverage
The drone is flying toward base camp from the north. Your location is vulnerable from that direction because terrain interference will allow the drone to fly in virtually undetected. You need more tracking.
The area of operations is very rugged and contains numerous dirt roads that are large enough to support the weight and size of the mobile radar vehicles. Being able to continuously track the drone is the best-case scenario. However, due to limitations on where the radar vehicles can be located, you've found two possible sites. You'll call one site "Radar North" and the second site "Radar West". All three sites are working as a small star topology radar system. Radar North and Radar West are in two-way communications with the Main Radar. Therefore, if one site starts tracking the drone, all three sites will work as a team to track it.
Reusing objects
Radar North and Radar West will be identical to Main Radar except for their positions. Copy the existing site and use it as the model for the two new sites.
- Select Main_Radar() in the Object Browser.
- Click Copy () in the Object Browser toolbar.
- Select Drone_Detection () in the Object Browser.
- Click Paste () in the Object Browser toolbar two (2) times.
You now have three radar sites in your scenario (Main_Radar, Main_Radar1, and Main_Radar2). All three radar sites have the same properties. STK renames objects with a one-up number. You need to reposition and rename the new radar sites. Main_Radar will remain at its original location.
Defining Radar North
- Rename Main_Radar1 () to Radar_North.
- Rename MainRadar_FOV1 () to RadarNorth_FOV.
- Open Radar_North's () properties ().
- Select the Basic - Position page when the Properties Browser opens.
- Set the following in the Position frame:
- Click to accept your changes and to close the Properties Browser.
- Select both Radar_North () and RadarNorth_FOV () in the Object Browser.
- Double-click Radar_North's () color icon.
- Change the color so that it does not match Main_Radar() and MainRadar_FOV ().
Option | Value |
---|---|
Latitude | 46.4071 deg |
Longitude | -122.232 deg |
Color Icons
When multiple items are selected in the Object Browser, clicking one of the color icons will allow you to choose the same color for all of them.
Defining Radar West
- Rename Main_Radar2 () to Radar_West.
- Rename MainRadar_FOV2 () to RadarWest_FOV.
- Open Radar_West's () properties ().
- Select the Basic - Position page when the Properties Browser opens.
- Set the following in the Position frame:
- Click to accept your changes and to close the Properties Browser.
- Select both Radar_West() and RadarWest_FOV () in the Object Browser.
- Double-click one of the color icons and change the color so that it does not match the other two sites.
Option | Value |
---|---|
Latitude | 46.298 deg |
Longitude | -122.492 deg |
View all three radar sites' fields of view
- Bring the 3D Graphics window to the front.
- Zoom to Main_Radar().
- Use your mouse features to zoom out until you can see all three (3) radar sites.
All Radar Sites
With all three radars in such a concentrated area, your 3D Graphics window looks a little cluttered. Since the domes are being used simply to visualize the range of the radar, you can remove them visually so that they don't obstruct your view. If you choose to use them for analysis, they'll still be available.
Removing the Sensor object graphics
You can quickly remove the Sensor () object graphics using the check box located beside the object in the Object Browser.
- Use the Ctrl key and the left mouse button to select all three (3) Sensor () objects in the Object Browser.
- Clear one of the Sensor () object's check box.
- Bring the 3D Graphics window back to the front.
When multiple items are selected in the Object Browser, clicking on one (1) of the check boxes will disable all of them.
radar sites with Azimuth-Elevation Masks
You have a good visual representation of which radar sites "might" see the cruise missile. Don't be fooled by this view. For instance, it would be easy to think that when the cruise missile turns south, Radar_North () can track it until it hits Blue Force base camp. Run further analysis and find out if this is the case.
Grouping the radar sites for analysis
Your radar sites are now ready for analysis. You need to know when these sites can track the cruise missile. You could do individual access calculations from each of your three radar sites, but it will be easier to use a Constellation () object to group the three sites and analyze them as a unit.
- Insert a Constellation () object using the Define Properties () method.
- Select the Basic - Definition page when the Properties Browser opens.
- Select Place () in the Selection filter frame. This will highlight all the Place () objects in the Available list.
- Move () the Place () objects to the Assigned Objects list.
- Click to accept your changes and to close the Properties Browser.
- Rename Constellation1 () to Radars.
Creating a Chain object
A chain is a list of objects (either individual or grouped into constellations) in order of access. In this case, the drone is flying toward the base camp and is being tracked by all three radars.
- Insert a Chain () object using the Define Properties () method.
- Select the Basic - Definition page when the Properties Browser opens.
Choosing your start and end objects
The first step in defining the Chain () object is to choose the start and end objects.
- Click the Start Object ellipsis ().
- Select Radars () in the Select Object dialog box.
- Click to close the Select Object dialog box.
- Click the End Object ellipsis ().
- Select Drone () in the Select Object dialog box.
- Click to close the Select Object dialog box.
Creating connections
The next step is to create your connections. In this scenario, it's very simple. The connection is from Radars () to Drone ().
- Click in the Connections frame.
- Click the From Object ellipsis ().
- Select Radars () in the Select Object dialog box.
- Click to close the Select Object dialog box.
- Click the To Object ellipsis ().
- Select Drone () in the Select Object dialog box.
- Click to close the Select Object dialog box.
- Click to accept your changes and to close the Properties Browser.
- Rename Chain1 () to Radars_To_Drone.
Three is better than one
Main_Radar () did not provide enough tracking time. It is time to see if these two new radar sites added to the main radar site provide more tracking time.
- Right-click Radars_To_Drone () in the Object Browser.
- Select Report & Graph Manager... () in the shortcut menu.
- Select the Complete Chain Access () report in the Installed Styles list when the Report & Graph Manager opens.
- Click .
- Keep the report and the Report & Graph Manager open.
Base camp needs two minutes of tracking time for the simulation to be successful. Based on the report's Total Duration, using all three radars together, they have approximately 2.5 minutes of combined tracking time.
One of the radar sites acquires the cruise missile on 1 Dec 2023 19:04:33. The drone reaches the base camp on 1 Dec 2023 19:08:52. Therefore, the base camp has slightly more than four (4) minutes of tracking time if radar dwell time is taken into account.
Determining which radar tracks the longest
Create a graph that provide a quick view of which radar tracks the drone the longest. The first tracking time is at 1 Dec 2023 19:04:33. The scenario start time is 1 Dec 2023 19:00:00.000 UTCG. If you generate the graph using default analysis times, there will be over four (4) minutes of space in the graph. Remove that space by changing Time Properties. You can copy and paste times from the Complete Chain Access report into the Time Properties section and make some minor time adjustments.
- Return to the Report & Graph Manager.
- Select the Specify Time Properties option in the Time Properties frame.
- Copy the first access time in the report and paste it into Start (e.g., 1 Dec 2023 19:04:33:371).
- Copy the last access time in the report and paste it into Stop: (e.g. 1 Dec 2023 19:08:52:180).
- Select the Use step size / time bound option.
- Enter 1 sec in the Step size field.
- Select the Individual Strand Access () graph in the Installed Styles list.
- Click .
Many users of STK decrease the Step size time when creating graphs. For graphs that have vertical increases and decreases, lowering the Step size usually creates a more rounded view of the graph line. In this instance, since the cruise missile is flying extremely fast, lowering the Step size presents a more detailed view of radar accesses.
Individual Strand Access Graph
Based on the graph, Radar_North () is in the best position to pick up and track Drone ().
Checking azimuth, elevation and range
The Complete Chain Access report provided the required information regarding tracking time. The next step is to know where to look. Time properties are set, so all you have to do is run another report called Access AER.
- Return to the Report & Graph Manager.
- Select the Access AER () report in the Installed Styles list.
- Click .
- Scroll through the report.
You will see positive and negative elevations. Remember, your radar sites are in mountainous terrain. The drone is hugging the terrain. There are times when the drone is above and below the radar sites.
Summary
You performed a simulation of a radar system that tracked a drone along a known flight route. The test took place in mountainous terrain. The drone flew fast and used terrain following techniques. You used Sensor () objects to simulate the known field of view of your tracking radars. The main radar site was fixed in place. Two other radars were mobile and could be moved throughout the test area. The purpose of the test was to determine if the main radar site can track the drone for at least two minutes. You used a local terrain file for analysis. You used a Place () object and placed it at the main radar's location. You restricted it to use the terrain file analytically and restricted its range to 50 kilometers. The first test determined that it couldn't track the drone for the required time needed for a successful test. You placed two more radar systems into the training area in different locations from the main radar. Combining all three radar systems into a Constellation () object, they functioned as a team. Using a Chain () object, you determined that you could track the drone for approximately four minutes.
Save your work
- Close all reports and graphs.
- Close the Report & Graph Manager.
- Save () your work.