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 training by contacting AGI Support at support@agi.com or 1-800-924-7244.

This lesson requires an Internet connection and STK 12.8 or newer to complete.

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.

Video Guidance

Watch the following video. Then follow the steps below, which incorporate the systems and missions you work on (sample inputs provided).

Creating a New Scenario

First, you must create a new STK scenario; then build from there.

Launch STK ().
Click Create a Scenario in the Welcome to STK dialog box.
Enter the following in the STK: New Scenario Wizard:

Option	Value
Name:	Drone_Detection
Start:	1 Dec 2023 19:00:00.000 UTCG
Stop:	+ 10 min

Click OK 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.

Save ( ) often during this lesson!

Turn Off STK Terrain Server

Since you'll use a local terrain file for analysis and visualization, turn off STK Terrain Server.

Right click on Open Drone_Detection ( ) in the Object Browser.
Select Properties ( ) in the shortcut menu.
Select the Basic – Terrain page when the Properties Browser opens.
Clear the Use terrain server for analysis check box.
Click OK to accept your change and to close the Properties Browser.

Turn 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 when Globe Manager opens.
Select Add Terrain/Imagery... () in the shortcut menu.
Click the Path: ellipsis () when the Globe Manager: Open Terrain and Imagery Data dialog box opens.
Browse to <STK Install Folder>\Data\Resources\stktraining\imagery> in the Select Image Directory when the Browse For Folder opens
Click OK.
Select the StHelens_Training.pdtt check box.
Click Add.
Click Yes when prompted to Use Terrain for Analysis.

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.

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 Insert... .
Select the Basic - Position page when the Properties Browser opens.
Set the following in the Position frame:

Option	Value
Latitude:	46.2927 deg
Longitude:	-122.271 deg
Height Above Ground:	10 ft (simulates the antenna height on the vehicle)

Click Apply.

Define 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	Select the check box

Click Apply.

Constrain 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.

Select the Constraints - Basic page.
Select the Max: check box in the Range frame.
Enter 50 km in the Max: field.
Click Apply.

Range is measured as the distance between the two objects (in this case between the Place () object and the cruise missile). 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 non-zero height above ground may look downward from that height to its ground model.

Display 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 the Show check box in the At Range frame.
Set the following:

Option	Value
Number of Steps:	5
Minimum Range:	0 km
Maximum Range:	50 km

Click OK to accept your changes and to close the Properties Browser.
Right click on Place1 () in the Object Browser.
Select Rename in the shortcut menu.
Rename Place1 () to Main_Radar.

View 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.
Click Properties ( ) in the 3D Window Defaults toolbar.
Select the Details page when the Properties Browser opens.
Select the Enable check box in the Label Declutter frame. This will make it easier to see the object labels in the 3D Graphics window.
Click OK to accept your change and to close the Properties Browser.
Right-click on 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.

Enhance 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, the Sensor () object can be used analytically. Both the Sensor () object and Place () object "see" the same thing. They simply provide different graphical representations.

Insert a Sensor () object using the Define Properties () method.
Select Main_Radar () when the Select Object dialog box opens.
Click OK.

Sensor Type

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.

Select the Basic - Definition page when the Properties Browser opens.
Open the Sensor Type: shortcut menu.
Select Complex Conic.
Enter 180 deg in the Half Angles Outer: field in the Complex Conic frame.
Click Apply.

Apply Analytical Terrain and Range Constraints

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 - Basic page.
Select the use check box in the Az-El Mask frame.
Select the Max: check box in the Range frame.
Enter 50 km in the Max: field.
Click Apply.

Visualize 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 the Use Constraints check box in the Field of View frame.
Select AzElMask in the list of constraints.
Click Apply.

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.

Select the 3D Graphics - Attributes page.
Enter 50 in the % Translucency: field in the Projection frame.
Click OK to accept your changes and to close the Properties Browser.

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.

Rename Sensor1 () to Main_RadarFOV.

View the combined sensor and place fields-of-view in the 3D Graphics window

Bring the 3D Graphics window to the front.
Right-click on 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 for both the Place () object and the Sensor () object.

Place Object and Sensor Object Situational Awareness

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: shortcut menu.
Select StkExternal.
Click the Filename: ellipsis ().
Browse to <STK Install Folder>\Data\Resources\stktraining\samples>.
Select Missile_Route.e.
Click Open.

When an ephemeris file is created during a different time period, pay attention to Overide the times contained in the file. This allows 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.

Select the Override the times contained in the file check box.
Click OK to accept your changes and to close the Properties Browser.
Rename the Aircraft1 () to Drone.

Change Your Perspective

Bring the 3D Graphics window to the front.
Right click on Drone () in the Object Browser.
Select Zoom To.

drone with Default Model

Using a realistic object model

Drone () is using the generic, default, aircraft model (aircraft.glb). Change it to a 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.mdl when the File dialog box opens.
Click Open.
Click Apply to accept your change and to keep the Properties Browser open.
Bring the 3D Graphics window to the front.

drone with New Model

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.
Open the Color: shortcut menu
Select white.
Open the Line Width: shortcut menu.
Select the line with maximum thickness
Click Apply 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:

Option	Value
Show	Select the check box
Interval	1.0 sec

Click OK 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.

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:

Option	Value
Show	Select the check box
Y Origin:	Top
Radius:	80

Click OK to accept your changes and to close the Properties Browser.
Right click on Main_Radar() in the Object Browser.
Select Zoom To.
Mouse around in the 3D Graphics window to get a better view of Main_Radar() and Drone ().

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, but it appears that the main radar can see it. However, for how long?

Access Analysis

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 on 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 Access... in the Reports frame.

Does base camp have the required two (2) minutes to track the drone?

Close the Access report.

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 AER... 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 towards 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.

Reuse 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.

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:

Option	Value
Latitude:	46.4071 deg
Longitude:	-122.232 deg

Click OK 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.

Color Icons

Change the color so that it does not match Main_Radar() and MainRadar_FOV ().

When multiple items are selected in the Object Browser, clicking on one of the color icons will allow you to choose the same color for all of them.

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:

Option	Value
Latitude:	46.298 deg
Longitude:	-122.492 deg

Click OK 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.
Right click on Main_Radar() in the Object Browser.
Select Zoom To.
Bring the 3D Graphics window to the front.
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.

When multiple items are selected in the Object Browser, clicking on one (1) of the check boxes will disable all of them.

Bring the 3D Graphics window back to the front.

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
Move () the Place () objects to the Assigned Objects list.
Click OK 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 towards 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 Drone () in the Select Object dialog box.
Click OK to close the Select Object dialog box.
Click the End Object: ellipsis ().
Select Radars () in the Select Object dialog box.
Click OK to close the Select Object dialog box.
Click Apply to accept your changes and to keep the Properties Browser open.

Creating connections

The next step is to create your connections. In this scenario, it's very simple. The connection is from Drone () to Radars ().

Click Add in the Connections frame.
Click the From Object: ellipsis ().
Select Drone () in the Select Object dialog box.
Click OK to close the Select Object dialog box.
Click the To Object: ellipsis ().
Select Radars () in the Select Object dialog box.
Click OK to close the Select Object dialog box.
Click OK to accept your changes and to close the Properties Browser.
Rename Chain1 () to Drone_To_Radars.

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 on Drone_To_Radars () 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 Generate... .

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.

Keep the report and the Report & Graph Manager open.

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).
Change the last three numbers to 000 (e.g. 1 Dec 2023 19:04:33:000).
Copy the last access time in the report and paste it into Stop: (e.g. 1 Dec 2023 19:08:52:180).
Change the last three numbers to 000 (e.g. 1 Dec 2023 19:08:52:000).
Select the Use step size / time bound option.
Enter 1 sec in the Step size: field.

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.

Select the Individual Strand Access () graph in the Installed Styles list.
Click Generate... .

Individual Strand Access Graph

Based on the graph, Radar_North () is in the best position to pick up and track Drone ().

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 Generate... .
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 which will track a drone along a known flight route. The test is taking place in mountainous terrain. The drone is flying fast and is using terrain following techniques. You used Sensor () objects to simulate the known field-of-view of your tracking radars. The main radar site is fixed in place. Two other radars are mobile and can 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.