Tracking an Aircraft using Aviator and Radar

  • Required Licenses: Pro, AMM, TIREM, and Radar.
  • TIREM (Terrain Integrated Rough Earth Model) should be installed for realism.

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 acceptible to have different results.

Problem Statement

You are conducting an exercise testing a surveillance radar system against a small UAV which is flying in rugged, mountainous terrain. An experimental aerostat containing a radar jamming package is tethered in a remote mountainous area 10,000 feet above ground level (AGL). Furthermore, you are testing whether or not the radar jammer on-board the aerostat can jam the surveillance radar.

Solution

Use Aviator to create a flight path using the STK Basic UAV model. Build a monostatic surveillance radar and create a custom graph to determine if you can track the UAV. Build a simulated aerostat with an attached radar jam system. Using another custom graph, determine if the aerostat can jam the surveillance radar.

Create a New Scenario

Create a new scenario using the default analysis time period.

  1. Launch STK ().
  2. Create a scenario ().
  3. Keep the default time period.

SAVE OFTEN!

Add Terrain

You need to add analytical terrain. If you have an Internet connection, Microsoft Bing Maps can be used for imagery. However, imagery is not required.

  • If you have previously created a *.pdtt file from the hoquiam-e.dem terrain data file during STK Comprehensive training or other advanced training, enable it for analysis.
  • If you have not already created the *.pdtt file, we have provided one for you.
  1. Launch the Globe Manager ().
  2. Use the Add Terrain/Imagery () option in the Globe Manager () to load your terrain file (*.pdtt) to the globe in the 3D Graphics window.
  3. If you haven't created a terrain file, browse to <STK install folder>/Help/stktraining/imagery and select StHelens_Training.pdtt.
  4. When prompted Use Terrain for Analysis:
    1. If you are using the hoquiam-e.dem terrain data file for analysis, do not enable terrain for analysis.
    2. If you haven't loaded the hoquiam-e.dem terrain data file for analysis, enable terrain for analysis.

Set Scenario Object Properties

Besides analytical terrain, the scenario will require other properties to be set for analysis.

Flight Path Warning

Aviator performs best in the 3D Graphics window when the surface reference of the globe is set to Mean Sea Level. You will receive a warning message when you apply changes or click OK to close the properties window of an Aviator object with the surface reference set to WGS84.

It is highly recommended that you set the surface reference as indicated before working with Aviator.

  1. Open the scenario's () properties ().
  2. Browse to the 3D Graphics - Global Attributes page.
  3. In the Surface At field, under Surface Reference of Earth Globes, select Mean Sea Level from the drop-down menu.
  4. Remain in the scenario's properties browser.

Scenario RF Environment

You will track the UAV in mountainous terrain. Therefore, enable TIREM if it's installed on your PC.

  1. Browse to the RF - Environment page.
  2. Select the Atmospheric Absorption tab.
  3. Enable Use and select the TIREM model.
  4. Leave the scenario's () properties () open.

Radar Cross Section (RCS)

Prior to setting up and constraining a radar system, STK Radar allows you to specify an important property of a potential radar target - its Radar Cross Section (RCS)

Since you'll only have one object that uses an RCS, you can set the properties at the scenario level. If you had multiple objects requiring an RCS that were different, you would insert the RCS at the individual object level.

  1. Browse to the RF - Radar Cross Section page.
  2. In the Band Properties Field, make the following changes:
  3. Option Value
    Swerling Case II
    Constant RCS Value: 4 dBsm
  4. Close the scenario () properties ().

Swerling Case II model fluctuations are more rapid and are assumed to be uncorrelated from pulse to pulse.

RCS Values can be expressed in decibels referenced to a square meter (dBsm). STK can use External Radar Files Since you don't have an external RCS file, use a constant value. A UAV would have a small dBsm.

The UAV Mission

Begin by entering waypoints into the scenario. Then, insert the airport from where the UAV will takeoff and land. Use the 3D Aviator Editing tool to build the mission.

Waypoints

There are multiple ways to design waypoints in STK. For this scenario, the UAV will fly direct to waypoints that can easily be inserted into your scenario using the Place object and the From City Database method and the Search by Address method.

  1. Using the Insert STK Objects tool, insert the following Place () objects using the From City Database method:
    • Eatonville (Washington)
    • Kelso (Washington)
  2. Using the Insert STK Objects tool, insert the following Place () object using the Search by Address method (only available if you have a valid internet connection.):
    • Mount St Helens, WA

    For step 2, if you do not have a valid internet connection, you will need to insert a default Place () object and set the latitude to 46.1913 deg and the longitude to -122.193 deg. Name the Place object "MountStHelens.

  3. To better see all the place objects' labels better, open the 3D Graphics window's properties.
  4. In the Label Declutter field select Enable.

Airport

Insert a local airport. This is where the UAV will begin and end its mission.

  1. Using the Insert STK Objects tool, insert the following Place () object using the Search by Address method:
    • Chehalis-Centralia Airport, WA

If you do not have a valid internet connection, you will need to insert a default Place () object and set the latitude to 46.6729 deg and the longitude to -122.985 deg. Name the Place object ChehalisAirport.

  1. In the Object Browser, select all four place () objects and open their properties ().
  2. Select the Basic - Position page.
  3. Enable the Use terrain data option.

You now have all the required place objects. Build a flight route.

3D Aviator Editing

To quickly add an aircraft to your scenario using the Aviator, you can utilize 3D Object Editing and the 3D Aviator Editing toolbar (3D Object Editing toolbar) to define an aircraft and its procedures directly in the 3D Graphics window. Since you're going to use the Basic UAV model, this procedure will be the fastest way to build your aircraft object.

  1. Insert an Aircraft () object into the scenario using the Insert Default method.
  2. Rename the aircraft, UAV.
  3. Right click to the right of the STK menu area and enable the 3D Aviator Editing tool.
  4. Place the 3D Object Editing and 3D Aviator Editing tools next to each other for easier use.
  5. 3D Object Editing and 3D Aviator Editing tools

  6. Zoom To Chehalis_Centralia_Airport_WA.
  7. If you have an Internet connection, continue with Internet Connection Steps.
  8. If you don't have an Internet connection, move to No Internet Connection Steps.

Internet Connection Steps

  1. Center on the runway.
  2. Centered Runway

  3. Select the Aircraft/UAV from the 3D Object Editing toolbar Object Selection drop-down list.
  4. Click the Object Edit Start/Accept () button to start the 3D Object Editing tool.
  5. Click the Switch to Aviator () button on the 3D Aviator Editing tool.
  6. Click OK when the warning window pops up.

Clicking OK enables the 3D Aviator Editing tool.

Build the Aircraft Procedure

First select the aircraft type. Then, by using 3D Aviator Editing menus and clicking on the 3D Graphics window, you can quickly build your aircraft procedures.

  1. In the 3D Aviator Editing tool, click the Select Aircraft () button.
  2. When the Select Aircraft window pops up, choose the Basic UAV and click OK.
  3. Choose Runway in the Aviator Site pull down window.
  4. Choose Takeoff in the Aviator Procedure pull down window.
  5. Using your mouse, shift-click on the center of the runway.
  6. Scroll out far enough to see one red ball at both ends of the Takeoff procedure.
  7. Place your cursor on the Takeoff @ Runway - WheelsRelease red ball, hold down your left mouse button, and drag and drop the red ball at the runway threshold for runway 16.
  8. Wheels Release

  9. Click the Object Edit Start/Accept () button to accept your changes.
  10. Zoom to the Aircraft object.

Modify the Aircraft's Runway Placement

Depending on how precise your clicks were in the 3D Graphics window, the Aircraft object's model could be above or below the surface of the map. Either way, instruct the Aircraft object to follow the terrain during the takeoff roll. Furthermore, compensate for the wheels to ensure, visually, that the wheels are touching the runway .

  1. Click the Object Edit Start/Accept () button to start the 3D Object Editing tool.
  2. Click the Modify Procedure () button in the 3D Aviator Editing tool.
  3. Make the following changes in the Takeoff Properties pop up window:
  4. Option Value
    Runway Altitude Offset 5 ft
    Use Terrain for Runway Altitude Enabled
  5. Click the Object Edit Start/Accept () button to accept your changes.
  6. Zoom to the Aircraft object.
  7. Once you are satisfied with the UAV's alignment, move to Continue Building the Flight Route.

If required, using the 3D Object Editing tool and the 3D Aviator Editing tool, continue to adjust the takeoff procedure until satisfied with the Aircraft object's alignment.

Aircraft Alignment

No Internet Connection Steps

If you don't have an Internet connection, you can use an airfield model to simulate the runway at Chehalis-Centralia Airport.

  1. Insert a Facility () object using the Insert Default method.
  2. Open the Facility () object's properties ().
  3. On the Basic - Position page, make the following changes:
  4. Option Value
    Latitude 46.677 deg
    Longitude -122.983 deg
    Use terrain data Enabled
  5. Browse to the 3D Graphics - Model page.
  6. Change the Model File to airport.mdl.
  7. Click Apply.

Adjust the Runway Offset

Return to the 3D Graphics window. You can see that the runway model is partially buried in the terrain. Use offsets to move the model to better represent the actual runway at the airport.

  1. Browse to the 3D Graphics - Offsets page.
  2. Enable Rotational Offset - Use, and change Z to 90 deg.
  3. Enable Translational Offset - Use and change Z to -15ft.

Rotational offset visually shifts the runway to a north/south direction which is similar to the actual runway. Translational offset visually raises the runway model up 15 feet which places the model above the terrain.

3D Aviator Editing

Add an Aircraft object to the scenario then edit the aircraft type and ts performance models using the Aviator Editing toolbar. This toolbar allows you to define an aircraft and its procedures directly in the 3D Graphics window. Since you're going to use the Basic UAV model, this procedure will be the fastest way to build the aircraft object.

  1. Using the Insert STK Objects () tool, Insert an Aircraft () object into the scenario using the Insert Default method.
  2. In the Object Browser, rename the Aircraft object "UAV".
  3. Extend the View menu.
  4. Extend the Toolbar menu and select the 3D Aviator Editing toolbar.
  5. Position the 3D Object Editing and 3D Aviator Editing tools beside each other for easier use.
  6. 3D Object Editing and 3D Aviator Editing tools

  7. Zoom To ChehalisAirport.
  8. Center on the runway.
  9. Alternate Runway Centered

    In the above image, the north end of the runway is to the left.

  10. Select the Aircraft from the 3D Object Editing toolbar Object Selection drop-down list.
  11. Click the Object Edit Start/Accept () button to start the 3D Object Editing tool.
  12. Click the Switch to Aviator () button on the 3D Aviator Editing tool.
  13. Click OK when the warning window pops up.

Clicking OK enables the 3D Aviator Editing tool.

Align the Aircraft on the Runway

Line the aircraft up with the runway for the Takeoff Procedure.

You'll be using the 3D Object Editing and 3D Aviator Editing toolbars to create your flight route to include takeoff and landing. STK can utilize DAFIF or the Digital Aeronautical Flight Information Files.

  1. Choose Runway in the Aviator site pull down window.
  2. Choose Takeoff in the Aviator Procedure pull down window.
  3. Using the mouse, shift-click on the center of the runway.
  4. Scroll out far enough to see one red ball at both ends of the Takeoff procedure.
  5. Place the cursor on the Takeoff @ Runway - WheelsRelease red ball, hold down the left mouse button, and drag and drop the red ball at the runway threshold (North End).
  6. Click the Object Edit Start/Accept () button to start the 3D Object Editing tool to accept the your changes.
  7. Zoom to the Aircraft () object.

Modify the Aircraft's Runway Placement

Depending on how precise your clicks were in the 3D Graphics window, the Aircraft object's model could be above or below the surface of the map. Either way, instruct the Aircraft object to follow the terrain during the takeoff roll. Furthermore, compensate for the wheels to ensure, visually, that the wheels are touching the runway.

  1. Click the Object Edit Start/Accept () button to start the 3D Object Editing tool.
  2. Click the Modify Procedure () button in the 3D Aviator Editing tool.
  3. Make the following changes in the Takeoff Properties pop up window:
  4. Option Value
    Runway Altitude Offset 10 ft
    Use Terrain for Runway Altitude Enabled
  5. Click OK.
  6. Click the 3D Object Editing tool's Object Edit Start/Accept () button to start the 3D Object Editing tool to accept the your changes.
  7. Zoom to the Aircraft object.

If required, using the 3D Object Editing tool and the 3D Aviator Editing tool, continue to adjust the takeoff procedure until your satisfied with the Aircraft object's alignment and wheel placement. You may be required to increase or decrease Runway Altitude Offset in the Takeoff Properties window using the Modify Procedure button.

Alternate UAV Alignment

Continue Building the Flight Route

Once satisfied with the takeoff procedure, save the runway you have defined to a catalog. You can use the cataloged runway when you create a landing procedure.

  1. Click the Object Edit Start/Accept () button to start the 3D Object Editing tool.
  2. Click the Modify Site () button in the 3D Aviator Editing tool.
  3. Name the runway Chehalis.
  4. Click Add To Catalog and then select OK to close the Add Successful pop up window.
  5. Adjust your 3D Graphics window view so that you are looking straight down at the map and zoom out far enough so that you can see all your waypoints and the airport.
  6. Select STK Static Object in the Aviator Site pull down menu.
  7. Ensure Basic Point to Point () is selected in the Aviator Procedure window.
  8. Shift-click on the waypoints in the 3D Graphics window in the following order:
    • Kelso
    • Mount_St_Helens_WA (Or MountStHelens)
    • Eatonville

Edit the Aircraft Procedure

  1. Change the Aviator Site to Runway from Catalog and the Aviator Procedure to Landing.
  2. Shift-click on Chehalis_Centralia_Airport_WA (Or ChehalisAirport).
  3. Select the Modify Procedure () button.
  4. In the Landing Properties window, make the following changes if you are using an Internet connection.
  5. Option Value
    Runway Altitude Offset 5 ft
    Use Terrain for Runway Altitude Enabled
    Delay enroute climbs and descents Enabled
  6. If you are using STK's airport model, change Runway Altitude Offset to 10 ft.
  7. Click the Object Edit Start/Accept () button to accept your changes.

Disable Line of Sight Constraint

The aircraft is lined up for a takeoff roll, flies to the selected waypoints, and lands back at the airport. There is one more important step. You are using TIREM so you should turn off line of sight in the Aircraft object's properties.

  1. Zoom to the Aircraft object.
  2. Open the Aircraft's () properties () and browse to the Constraints - Basic page.
  3. Disable Line of Sight.

Surveillance Radar

The surveillance radar is located in a central location of the training area.

  1. Insert a Place () object using the From City Database method.
  2. Enter Mossyrock as the City Name, select Mossyrock Washington and insert it into the scenario.
  3. Open Mossyrock's () properties ().
  4. On the Basic - Position page, enable Use terrain data.
  5. Click OK.
  6. Zoom to Mossyrock.

The radar will be built using specifications from an The Airport Surveillance Radar, Model 11 (ASR-11). However, instead of creating a spinning antenna, you will lock the antenna onto the UAV.

Servomotor

The Radar object's antenna can be bore-sited. However, in STK, if you have an antenna that can track another object, use a Sensor object as the servomotor.

  1. Insert a Sensor () object using the Default method and attach it to Mossyrock.
  2. Open the Sensor's () properties ().
  3. On the Basic - Definition page, in the Simple Conic field, change the Cone Half Angle to 1 deg. You will use the Sensor objects projection for situational awareness (where the antenna is pointing).
  4. Click OK.

Visualize Axes

The Sensor object is attached to the center point of the Place object (its parent). The height of the antenna varies, but in this analysis, the antenna is 50 feet in altitude. It's always a good idea to visualize the parent object's axes. When you know this, it will make it easier to move the child object along the correct axis.

  1. Open Mossyrock's () properties () and browse to the 3D Graphics - Vector page.
  2. In the Axes tab, enable the Show option for the Body Axes option.
  3. In the Common Options field, change the Scale Relative to Model - Scale: to 1.5.
  4. Bring the 3D Graphics window to the front and look at the body axis for Mossyrock.

Reposition the Sensor

Facility, place and target objects have body-fixed coordinate axes, which align the x-axis along local horizontal North direction, the y-axis along local horizontal East direction, and the z-axis along local Nadir direction. Therefore, if you desire to leave the parent object (in the case the Place object) on the ground, but you want to move the child object (in this case the Sensor object) up, you move the child along the parent's axis, not the child's. In this instance, if you want to move the Sensor object up in altitude, you will use the parent's Z body. Since the positive Z points to Nadir (down), you will use a negative value to move the sensor object up along the parent's Z body.

  1. Open the Sensor's () properties ().
  2. Browse to the Basic - Location page.
  3. Change the Location Type to Fixed and enter -50ft for Z:.
  4. Click Apply.
  5. After applying your change, return to the 3D Graphics window. You will see that the Sensor object is elevated in altitude (50 feet).

Target the UAV

As stated earlier, the radar will lock on to the UAV. The Sensor object is acting as a servomotor. Target the sensor which in turn will target the antenna later in the lesson.

  1. Browse to the Basic - Pointing page.
  2. Change the Pointing Type to Targeted and move the UAV to the Assigned Targets list.
  3. Browse to the Constraints - Basic page and disable Line of Sight.

If Line of Sight is checked, access to the object is limited to lines of sight not obstructed by the ground. Although you are using terrain and the distances involved are not all that great, turning off Line of Sight will ensure that the Sensor object always follows the UAV (again, for situational awareness). If you return to the 3D Graphics window, slow down the Time Step to 1.00 sec and click the Start button in the Animation tool. As you watch the Sensor object track the UAV, you will see that, at times, you have unobstructed line of sight. At other times, the UAV dips behind terrain. Both the terrain and distance from the radar site will affect how well your radar can track the UAV.

Model the Radar

For this analysis, you will use a single beam. The Radar object will be a child of the Sensor object. Since the Sensor object is bore sighted towards the UAV, the Radar object, which is pointing along the parent's Z body, will point at the UAV. (Orientation Methods) You'll start with the mode.

  1. Insert a Radar () object using the Insert Default method, and attach the Radar object to the Sensor object (the servomotor).
  2. Open the Radar's () properties ().
  3. On the Basic - Definition page, ensure the Type: is Monostatic.

Radar Mode

  1. In the Waveform tab, change the Pulse Width to 1e-005 sec.
  2. Select the Probability of Detection tab.
  3. Open the Probability of False Alarm: pull down menu and select Format.
  4. In the Notation field, enable Scientific and click OK.
  5. Change the Probability of False Alarm to 1.000000e-006.
  6. Select the Pulse Integration tab.
  7. Open the pull down menu and select Fixed Pulse Number.
  8. Change Pulse Number to 5 (five).
  9. Select the Doppler Filters tab.
  10. Enable Main Lobe Clutter (MLC) and set the Bandwidth to 20 m/s.

Set Antenna Specifications

Select the antenna and change its design to specifications.

  1. Click the Antenna tab.
  2. In the Model Specs tab, change the type to Cosine Squared Aperture Rectangular. (Rectangular Cosine Antenna)
  3. Set the following Antenna Size Options:
Option Value
Use Beamwidth Enabled
X Dim Beamwidth 14 deg
Y Dim Beamwidth 4 deg
Main-lobe Gain Disable Computed and change to 30 dB
Efficiency 55 %

Build the Transmitter

  1. Click the Transmitter tab.
  2. Enable Frequency and change the value to 2.9 GHz.
  3. Change Power to 25 kW.

Enable TIREM

The last step is to ensure that TIREM is used in the analysis.

  1. Browse to the Constraints -  Basic page.
  2. Disable Line of Sight.

You are ready to determine the radar's tracking ability.

Analyze the Radar

The first step is to determine how well your radar can track the UAV.

  1. In the Object Browser, right click on the Radar object () and open the Access () tool.
  2. In the Associated Objects List, select UAV (the Aircraft object) and click the Compute button.
  3. Click the Report & Graph Manager... button.

Create a Custom Graph

For your analysis, you are interested in two report contents, S/T PDet1 (Search/Track Probability of detection) and Range. By creating a custom graph that contains these contents, you can quickly determine the effectiveness of your radar.

  1. Select the My Styles folder and click the Create new graph style button.
  2. Give the graph a name such as "Pdet and Range" and click the Enter key on your keyboard. This will take you to the custom graph's properties.
  3. In the Data Provider window, expand Radar Search Track.
  4. Move S/T PDet1 to the Y Axis window.
  5. Return to the Data Provider and expand AER Data and then Default.
  6. Move Range to the Y2 Axis.
  7. Click OK.
  8. In the Time Properties field, enable Specify Time Properties.
  9. Enable Use step size / time bound.
  10. Set Step Size: to 1 sec.
  11. Generate the graph.

PDet Range Graph

You are looking for a PDet of 0.5 or greater. It's a given that as distance increases, your PDet will decrease. There are instances where your tracking drops well below a PDet of 0.5. Using the Toggle animation time line button, right clicking on the graph, and selecting Set Animation Time, enables you to jump back to the 3D Graphics window to visualize what is occurring. In the following picture, you can see that the UAV is flying behind a mountain based on the time line shown in the PDet Range Graph.

UAV Behind Mountain

Overall, the radar system is able to track the UAV. It's time to see if you can jam the radar.

Radar Jamming

You will simulate an aerostat flying near Mount St. Helens. The aerostat is tethered at 10000 feet AGL.

  1. Insert a Place () object using the Insert Default Method (Jam Site).
  2. Open the Jam Sites () properties ().
  3. On the Basic - Position page, make the following changes:
Option Value
Latitude 46.1173 deg
Longitude -122.315 deg
Use terrain data Enabled
Height Above Ground 10000 ft

You can model the radar jammer by simply reusing the previously built surveillance radar and making a couple of changes. You'll use some specifications from the AN/ALQ-99 Tactical Jamming System (TJS).

The Jammer

As previously stated, you can reuse the surveillance radar that's attached to Mossyrock.

  1. In the Object Browser, copy the Sensor object (Servomotor) and paste it to the Jam Site.
  2. If desired, give the both the Sensor and Radar objects new names.
  3. Open the Jam Site's sensor's () properties ().
  4. Browse to the Basic - Location page and change the Location Type to Center.
  5. Browse to the Basic - Pointing page.
  6. Remove UAV from the Assigned Targets list and replace it with Mossyrock.
  7. Return to the 3D Graphics window.

Define the Jammer

The Jam Site is at 10000 feet AGL. The Sensor object is attached to the Jam Site's center and is targeting Mossyrock (surveillance radar site). Make the required specification changes to the jammer using a couple TJS specifications.

  1. Open the Jam Radar () properties ().
  2. On the Basic - Definition page, select the Antenna tab and change the Type to Square Horn.
  3. Change the Diameter to 1ft (one foot).
  4. Select the Transmitter tab.
  5. Change the Power to 10.8 kW.
  6. Click OK.

Jam the Radar

The next step is to tell the surveillance radar that it's being jammed.

  1. Open the surveillance Radar () properties ().
  2. On the Basic - Definition page, select the Jamming tab.
  3. Enable Use and move the jam Radar object to the Assigned Jammers field.
  4. Click OK.

You are now ready to analyze the jammer's effectiveness against the surveillance radar.

Jam Effectiveness

Create a custom graph that shows only those contents you are interested in for your analysis. You are interested in S/T PDet1 (Search/Track Probability of detection) and S/T PDet1 w/ Jamming (Search/Track Probability of detection with jamming).

  1. In the Object Browser, right click on the surveillance Radar () and open the Access () tool.
  2. In the Associated Objects List, select UAV (the Aircraft object).
  3. Click the Report & Graph Manager... button.
  4. Select the My Styles folder and click the Create new graph style button.
  5. Give the graph a name such as PDet Jamming then click the Enter key on your keyboard.
  6. In the Data Provider window, expand Radar Search Track.
  7. Move S/T PDet1 to the Y Axis window.
  8. Move the S/T PDet1 w/ Jamming to the Y Axis window.
  9. Click OK .
  10. In the Time Properties field, enable Specify Time Properties.
  11. Enable Use step size / time bound.
  12. Set Step Size: to 1 sec.
  13. Generate the graph.

By placing the Pdet and Pdet with jamming on the same axis, it's easier to read the graph. As you can see by looking at the graph, except for some sporadic break through periods, the jammer attached to the aerostat is effectively jamming the surveillance radar.

PDet With Jamming

Don't forget to save your work!