STK Tutorial

STK Tutorial

Analyt ical Graphics, Inc. www.agi.com [email protected] 610.981.8000 800.220.4785

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This document and the software described in it are the proprietary and trade-secret information of Analytical Graphics, Incorporated. They are provided under, and are subject to, the terms and conditions of a written software license agreement between Analytical Graphics, Incorporated and its customer, and may not be transferred, disclosed or otherwise provided to third parties, unless otherwise permitted by that agreement. Use, reproduction or publication of any portion of this material without the prior written authorization of Analytical Graphics, Incorporated is prohibited. While reasonable efforts have been taken in the preparation of this manual to ensure accuracy, Analytical Graphics, Incorporated assumes no liability resulting from any errors or omissions in this manual, or from the use of the information contained herein.

Copyright 2010 Analytical Graphics, Incorporated.

All Rights Reserved.

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Contents CREATING THE STKTUTORIAL SCENARIO .................................................... 4 SETTING THE STKTUTORIAL ENVIRONMENT ................................................ 5

Setting Application Properties ............................................................. 5 SAVING THE SCENARIO........................................................................... 6 CREATING FACILITIES............................................................................. 6

Defining Facilities ......................................................................... 6 The Facility Database ...................................................................... 7 Setting 2D Graphics Attributes ............................................................ 8

CREATING A TARGET ............................................................................. 9 CREATING A SHIP .................................................................................. 9 DISPLAYING AND MODIFYING A MODEL.................................................... 10 CREATING SATELLITES ......................................................................... 11

Using the Orbit Wizard .................................................................. 11 Using the Satellite Database............................................................. 12 Defining Orbital Parameters ............................................................. 13 2D Graphics Properties .................................................................. 17

MAP PROJECTIONS .............................................................................. 18 Creating a New 2D Graphics View...................................................... 18 Sampling Map Projections ............................................................... 19

ADDING AN AREA TARGET..................................................................... 20 USING THE 3D OBJECT EDITOR ............................................................... 21 WORKING WITH THE 3D GRAPHICS TOOLBAR MANAGING VIEWS................... 23 CALCULATING ACCESS ......................................................................... 25 WORKING WITH SENSORS...................................................................... 25

Defining and Pointing Sensors........................................................... 25 Limiting a Sensor's Visibility............................................................ 28

STATIC & DYNAMIC DISPLAY OF DATA ..................................................... 30 Reports & Graphs ........................................................................ 30 Dynamic Displays & Strip Charts ....................................................... 31

SETTING CONSTRAINTS ........................................................................ 33 CREATING A WALKER CONSTELLATION .................................................... 35 CONCLUSION ..................................................................................... 37

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OVERVIEW This tutorial presents exercises that will assist you in developing a solid understanding of the basic functions in STK as well as a brief introduction to some of STKs more advanced features and functions. The tutorial is intended to help you develop a context in which to place the fine details of STK as you begin to work with the program and its modules. Use the demo scenarios shipped with STK and the tutorial that follows to become familiar with the basic structure of STK as well as its functions and features.

Licenses Needed: This tutorial requires that you be licensed for the STK Professional Edition.

Although this tutorial introduces the user to many of the features available in STK, it addresses only a small sampling of STK functionality. For a complete explanation of all STK functions, please consult the STK Online Help system or take one of our extensive training classes.

Creating the STKTutorial Scenario

Note: To ensure that you do not accidentally overwrite your previous work, save each scenario in a separate folder and name the folder with the same name as the scenario.

The scenario is the highest-level object in STK; it includes one or more 2D and 3D Graphics windows and contains all other STK objects (e.g., satellites, facilities, etc.). This section of the tutorial guides you through the process of creating and populating a scenario.

1. Start STK.

2. To create a new scenario, click the (Create a New Scenario) icon in the Welcome to STK! window. The STK: New Scenario Wizard will appear. This is a window designed to help streamline the process of creating, saving, and organizing scenario files.

3. Rename the scenario STKTutorial.

4. You can add a unique description so that you can remember the reason you created this scenario. Enter Learning the basics of STK.

5. Set the Analysis Period Start Time to 1 Jul 2007 12:00:00.000 UTCG.

6. Set the Analysis Period End Time to 2 Jul 2007 12:00:00.000 UTCG.

7. Click OK. A 2D and 3D Graphics window appears. Also the Insert STK Objects window appears.

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Note: For publication purposes, 2D Graphics colors have been reversed. In most instances, the 2D Graphics window is a color-on-black display.

. Tip: To change the size of the 2D or 3D Graphics window, click and hold the mouse

button on any of the corners and drag the window border. When you release the mouse button, the window re-sizes. The aspect ratio of the map projection is preserved automatically by STK, by creating blank space in the window when its size does not fit the correct ratio. Click the (2:1 Aspect Ratio) button on the 2D Graphics toolbar to resize the window to eliminate this blank space.

You are now ready to start building a scenario.

Setting the STKTutorial Environment Before performing any tasks in STK, you need to set parameters that will affect all aspects of your scenario as it is built.

Setting Application Properties First, we will set some application parameters for STK. These high-level parameters affect every object within the application, regardless of the scenario currently open.

1. To set parameters for the STK application, click Edit Preferences on the Insert STK Objects window.

2. In the window that appears, select Save/Load Prefs.

3. In the Ephemeris frame, verify that Save Vehicle Ephemeris is on and Binary Format is off.

4. Verify that Save Accesses is disabled.

5. Verify that Auto Save is on.

6. Verify that Save Period is set to 300 sec (5 min).

7. Click OK to apply any changes and to dismiss the Preferences window.

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Saving the Scenario Before proceeding to the next section, save the STKTutorial scenario. Select Save from the File menu or click the (Save) button. This saves the scenario and all the objects you created and defined for the scenario, including the properties that you entered or selected.

Creating Facilities Now you are ready to populate the scenario with various objects. Start with facilities such as ground stations, launch sites, and tracking stations.

1. Bring up the Insert STK Objects window. If the Insert STK Objects window is not shown, click the Insert STK Objects button ( ) on the default toolbar.

2. Select Facility ( ) in the Scenario Objects field.

3. Select Define Properties.

4. Click Insert This will bring up the properties for the facility.

Defining Facilities

1. Select the Basic Position page.

2. On the Position page, ensure that the Type is set to Geodetic.

3. Set Latitude to 48.0 and Longitude to 55.0. Leave Altitude at its default setting of 0.

4. Select the Basic - Description page.

5. Enter a Short Description, such as "Launch Site."

6. Enter a Long Description, such as "Launch site in Kazakhstan. Also known as Tyuratam."

7. Click OK.

8. Select the Facility in the Object Browser.

9. Click F2 to rename the facility to Baikonur.

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10. Use the procedures described above to add the facilities listed in the following table (don't worry about the Long Description).

Table 1. Settings for Perth & Wallops facilities

Name Latitude Longitude Altitude Short Description

Perth -31.0 116.0 0.0 Australian Tracking Station

Wallops 37.8602 -75.5095 -0.0127878

NASA Launch Site/Tracking Station

11. When you finish defining each facility, click OK.

The Facility Database Now you will use the Facility Database to add two more facilities to the scenario.

1. Bring up the STK Insert STK Objects window.

2. Select Facility ( ) in the Scenario Objects field.

3. Select Select From Facility Database in the Select A Method field.

4. Click Insert This will bring up the Facility Database.

5. Click Advanced

6. Turn on the Network option, and select NASA DSN as the Network.

7. Click OK.

8. Scroll to the bottom of the list in the Facility Database Search Results window and highlight Santiago and WhiteSands. (Select one of them, then hold down the CTRL key and click on the other.)

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9. Click Insert to add the facilities.

10. Click Close on the Facility Database.

11. Open the Basic Properties window for the Santiago facility and select Description.

12. Note that the Long Description field includes position and other data about the facility.

Note: When objects are inserted using any of the databases shipped with STK, descriptions are automatically generated for the objects.

13. Click OK or Cancel.

14. Close the Insert STK Object window.

Setting 2D Graphics Attributes A variety of 2D graphics properties can be set for a facility in STK.

1. Select a facility whose color you would like to changee.g. because it does not show up clearly against the background.

2. Open the facilitys Properties by clicking the Properties button ( ) in the Object Browser toolbar.

3. Select the 2D Graphics - Attributes page.

4. Select the desired color.

5. Click OK.

6. Repeat steps 1-2 for any other facilities whose color you wish to change.

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Creating a Target

The target for this exercise is a glacier field over North America. You are going to insert the target using the Object Catalog.

1. Insert a target ( ) from the Object Catalog ( ).

2. Change the target's name to Iceberg.

3. Open the Icebergs Properties Browser.

4. On the Position page, verify that the Type is set to Geodetic.

5. Enter a Latitude of 74.91 and a Longitude of -74.5.

6. Open the Description page and enter a short description, such as "Only the tip of the Iceberg."

7. Click OK.

Creating a Ship

STK objects include three types of great arc vehiclesaircraft, ships, and ground vehicles. In this exercise you will create a ship.

1. Insert a ship ( ) from the Object Catalog, and change its name to Cruise.

2. Open the Cruises Properties Browser.

3. On the Route page, ensure the Start Time is set to your default scenario start time.

4. Ensure the Propagator is set to GreatArc.

5. Ensure the Route Calculation Method is set to Smooth Rate.

Note: Once you enter a Rate and Start Time for a great arc vehicle, STK automatically calculates the Stop Time and displays it in a read-only field.

6. Enter the waypoint values shown in the following table for the ship in the waypoints table. To insert a line of data, click the Insert Point button.

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Table 2. Ship waypoints

Latitude Longitude Altitude Speed

44.1 deg -8.5 deg 0.0 km .015 km/sec

51.0 deg -26.6 deg 0.0 km .015 km/sec

52.1 deg -40.1 deg 0.0 km .015 km/sec

60.2 deg -55.0 deg 0.0 km .015 km/sec

68.2 deg -65.0 deg 0.0 km .015 km/sec

72.5 deg -70.1 deg 0.0 km .015 km/sec

74.9 deg -74.5 deg 0.0 km .015 km/sec

7. Select the Basic - Attitude page.

8. Ensure ECF velocity alignment with radial constraint is selected.

9. Open the 2D Graphics - Route page.

10. Make certain that Show Turn Markers is turned on and click OK.

11. In the Animation toolbar, click the (Reset) button, and look at the 2D Graphics window.

Displaying and Modifying a Model All objects in STK are represented in the 3D Graphics window by models. There are default models for standard objects, as well as models designated for specific objects that you might import into a scenario, such as the Cruise Liner, which we will be examining in this exercise. For any object in STK, you can change the model to something other than what is initially assigned to it.

1. Open the Properties Browser for the Cruise.

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2. Select 3D Graphics - Model.

3. In the Model frame, verify that Show is enabled, and that Scale is set to 0.0.

4. In the Detail Thresholds frame, disable Use.

5. To change the model, click the ellipsis button in the Model File field.

6. Browse to the model cruise_liner.mdl.

7. Click Open.

8. Click OK.

9. Select the 3D Graphics window.

10. Click View From/To ( ) in the 3D Graphics window toolbar.

11. In the View From field, select the Cruise. The Cruise Liner will also become highlighted in the View To field.

12. Click OK.

13. The Cruise Liner should now appear front and center in the 3D Graphics window.

Creating Satellites

Now you will add a few satellites to the scenario, namely an Earth Resources Satellite (ERS1), a Space Shuttle, and two Tracking & Data Relay (TDRS) satellites.

Using the Orbit Wizard The STK Orbit Wizard provides a quick and easy way to generate a variety of frequently used satellite orbit patterns.

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1. Click the Insert Object ( ) button to bring up the Insert STK Object window.

2. Select Satellite ( ) in the Scenario Object field.

3. Select Orbit Wizard ( ) in the Select A Method field.

4. Click Insert to launch the Orbit Wizard.

5. Select Geosynchronous as the Type.

6. Set the Satellite Name to TDRS.

7. Ensure the Subsatellite point is set to -100 deg.

8. Ensure the Use Scenario Time Period option is on.

9. Click OK on the Orbit Wizard.

Using the Satellite Database STK is shipped with a rich and extensive set of satellite databases, together with an interface to make it easy to find and propagate the satellite of interest. Here you will use the Satellite Database to define a second TDRS satellite for your scenario.

1. Bring up the Insert STK Object window.


3. Select Select from Satellite Database in the Select A Method field.

4. Click Insert

You can quickly generate a list of all TDRS satellites in the database. To do that, use an asterisk (*) as a wild card in the Common Name field. Lets try this.

5. Turn On the Common Name field.

6. Type TDRS* in the text field.

7. Turn Off the SSC Number option.

8. Click Search to perform a search for all active TDRS satellites.

9. In the search results window, select TDRS 3.

10. Click the Time Period button.

11. Ensure the Use Scenario Time Period is selected.

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12. Click OK.

13. Click Insert Satellite.

14. For this step you need an active Internet Connection. If you do not have an internet connection, you need to click the Advanced button in the Satellite Database. Turn On Use Default Satellite Database. Click OK. This will allow you to enter the TDRS_3 satellite into the scenario.

15. Click Close in the Satellite Database window.

16. Close the Insert STK Object Tool.

17. Rename the satellite to TDRS_3.

If the 2D Graphics window does not show your new TDRS satellites, click the (Reset) button.

Note: The ground tracks for both satellites display in the 2D Graphics window as

specks since they are in geostationary orbit.

Defining Orbital Parameters A great variety of satellite orbits can be propagated using the Orbit Wizard and Satellite Database. In addition, STK allows you to define any satellite orbit precisely using a number of propagators and force models. You will now add two satellites to the scenario using the J4 Perturbation propagator, which accounts for secular variations in the orbit elements due to Earth oblateness.

1. Create a new satellite using Insert STK Objects.

2. Select Satellite ( ) in the Scenario Objects field.

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3. Select Define Properties in the Select A Method field.

4. Click Insert to launch the Properties page.

5. Select the Basic Orbit page.

6. Select J4 Perturbation as the Propagator.

7. Enter the orbital parameters for ERS1, found in the following table. Use the down-pointing arrow to change the default RAAN (Right Ascension of the Ascending Node) option to Lon Ascn Node (Longitude of Ascending Node) before entering the values listed in the table.

Table 3. Orbital elements for ERS1

Orbital Element Setting

Start Time Use Scenario Analysis Period

Stop Time Use Scenario Analysis Period

Step Size 60.00

Orbit Epoch Scenario Default Start Time

Coordinate Type Classical

Coordinate System J2000

Semimajor Axis 7163.14 km

Eccentricity 0.0

Inclination 98.50 deg

Argument of Perigee 0.0 deg

Lon Ascn Node 99.38 deg

True Anomaly 0.0 deg

8. When you finish, click Apply, and then click the (Reset) button.

9. Rename your satellite ERS1.

10. Your 2D Graphics window should look like this:

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11. Open the satellites 2D Graphics - Pass page.

12. To display only the descending side of the orbit, change Visible Sides from Both to Descending and click Apply.

13. Observe the change in the 2D Graphics window.

14. When you finish, return the Visible Sides option to Both and click OK.

15. Bring up the Insert STK Objects window.


17. Select Define Properties in the Select A Method field.

18. Click Insert to launch the Properties page.

19. On the Orbit page for the Shuttle, select J4Perturbation as the Propagator.

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20. Use the down-pointing arrow to change the default setting of Semimajor Axis to Apogee Altitude. The default Eccentricity option will automatically change to Perigee Altitude.

21. Use the down-pointing arrow to change the default setting of RAAN to Long Of Ascending Node.

22. Enter the orbital elements for the Shuttle as given in the following table.

Table 4. Orbital elements for the Shuttle

Orbital Element Setting

Start Time Use Scenario Analysis Period

Stop Time Use Scenario Analysis Period

Step Size 60.0 sec

Orbit Epoch Default Start Time

Coordinate Type Classical

Coordinate System J2000

Apogee Altitude 370.4 km

Perigee Altitude 370.4 km

Inclination 28.5 deg

Argument of Perigee 0.0 deg

Long of Ascending Node -151.0 deg

True Anomaly 0.0 deg

23. When you finish, click OK.

24. Rename the new satellite Shuttle.

25. Open the Properties Browser for the Shuttle.

26. Select 3D Graphics - Model.

27. In the Model frame, verify that Show is enabled, and that Scale is set to 0.0.

28. In the Detail Thresholds frame, disable Use.

29. To change the model, click the ellipsis button in the Model File field.

30. Browse to the model shuttle-05.mdl.

31. Click Open.

32. Click OK.

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35. In the View From field, select the Shuttle. The Shuttle will also become highlighted in the View To field.

36. Click OK.

2D Graphics Properties You have already become acquainted with the Pass page of the satellites 2D Graphics properties. Now you will use the Shuttle to experiment with further graphics features.

1. Open the Properties Browser for the Shuttle, and select the 2D Graphics - Attributes page.

2. Change the Line Style to dashed and the Marker Style to Plus, and click Apply.

3. Now select the 2D Graphics - Contours page.

4. Turn On the Show option for Elevation Contours.

5. In the Level Attributes area, click Remove All to remove any existing entries from the Level list.

6. In the Level Adding area, make sure the Add Method is set to Start, Stop, Step, then enter 0, 50 and, 10 for the Start, Stop and Step values, and click Add.

7. In the Level list, highlight the first level (0.00) and turn OFF the ShowLabel field. Change the Color, and/or Line Style, and/or Line Width if you wish.

8. Repeat step 7 for the remaining levels.

9. Click OK.

10. To see the contour levels, click the (Reset) button. Zooming in will provide a better view.

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11. When you finish, zoom out to a normal 2D Graphics view.

Note: To zoom in on a region in the 2D Graphics window, click the (Zoom In) button in the graphics window, place the mouse pointer in one corner of the region of interest, hold down the left mouse button, and drag the pointer to the opposite corner of the selected region. You can do this repeatedly. To restore the full 2D Graphics window view, click the (Zoom Out) button as often as necessary.

Map Projections In this section of the Tutorial you will create a second 2D Graphics window and become acquainted with some of the map projections available with STK.

Creating a New 2D Graphics View

1. From the View menu, select Duplicate 2D Graphics Window 2D Graphics 1 Earth.

2. When the second 2D Graphics window appears, move it so that you can see both 2D Graphics windows at once.

Note: It may be helpful to float one of the 2D Graphics windows so that you can move it out of the workspace. Simply right-click on the windows title bar, select Floating from the choices presented, hold down the CTRL key, and drag the window to the desired location.

3. Select the new 2D Graphics window, and click the button in the 2D Graphics window to launch its 2D Graphics properties window.

4. Open the Projection page.

5. In the Projection Format frame, change the Type to Perspective.

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6. Set the Display Coordinate Frame to ECI.

7. In the Center field, enter Latitude of -3.418 deg.

8. Enter the Longitude of 54.99 deg.

9. Enter 35000 km as the Altitude.

10. Click OK to view the changes in the 2D Graphics window. If the satellite orbits do not appear, click the (Reset) button.

Sampling Map Projections

1. Select the original 2D Graphics window (2D Graphics - Earth), and click the button to display its properties.

2. Move the 2D Graphics properties window into a position where you can see it and the 2D Graphics window simultaneously.

3. Open the Projection page and open the Type list in the Projection Format frame.

4. Select any other projection (such as the Sinusoidal projection shown below), and click Apply to see it in the 2D Graphics window.

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5. Browse through the available projections by repeating Step 4 for each projection listed in the dropdown list.

6. When you finish, restore the first 2D Graphics window to Equidistant Cylindrical, and click OK to dismiss the 2D Graphics properties window.

Adding an Area Target

Area targets are used to define geographical regions of interest on the ground. Lets assume that the Cruise ship has run into the Iceberg. You will now create an area target that defines the search area for survivors.

1. Insert an area target ( ) from the Object Catalog, and name it SearchArea.

2. Launch the area targets Properties Browse, and open the 2D Graphics - Attributes page.

3. Set the Marker Style to None.

4. Turn Off the Inherit from Scenario, Show Label, and Show Centroid options.

5. Open the Basic - Boundary page.

6. Click the Add button to insert a boundary point. Double-click the field under Latitude and enter the value 78.4399. Similarly, double-click the field under Longitude and enter a value of 77.6125.

7. Repeat step 6 until you have entered all of the boundary points in the following table:

Table 5. Area target boundary points

Latitude Longitude

77.7879 -71.1578

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Latitude Longitude

74.5279 -69.0714

71.6591 -69.1316

70.0291 -70.8318

71.9851 -76.3086

8. Click Apply when done.

9. Now open the Basic - Centroid page.

10. Turn off the Auto Compute Centroid option.

11. Set the Position Type to Spherical.

12. Enter 74.9533 as the Latitude, -74.5482 as the Longitude, and 6358.186790 as the Radius.

13. Click OK.

14. Zoom the 2D Graphics window in on the region around the area target; then, when you are finished, zoom out again.

Using the 3D Object Editor Facilities, area targets, and great arc vehicles can have their boundaries or routes edited directly within the 3D Graphics window using the 3D Object Editor. This exercise explores the basics of using the 3D Object Editor.

1. In the View menu, select the Toolbars 3D Object Editing toolbar.


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3. Click Home View on the 3D Graphics Toolbar to set your view to the default position.

Lets zoom in on the region around the area target in the 3D Graphics window.

4. Click and hold the left mouse button, then move your mouse around in the 3D Graphics window to rotate the globe.

5. Click and hold the right mouse button, then move your mouse forward and backward to zoom in and out.

6. Now Zoom In on the region around the area target.

7. In the 3D Object Editing toolbar, select Area Target/SearchArea from the drop-down menu.

8. Click Object Edit Start/Accept to begin editing the SearchArea area target in the 3D Graphics window. The boundary points of the SearchArea area target are now highlighted in the 3D Graphics window.

9. By clicking and dragging with the mouse, expand the SearchArea area targets boundaries to encompass a larger area. Notice that while editing the object, the usual mouse controls for manipulating the view in the 3D Graphics window function normally.

10. Click Object Edit Start/Accept to apply the changes. The area target now has new boundaries.

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Working with the 3D Graphics Toolbar Managing Views In this exercise, you will learn to establish custom views that will be more useful or appealing than the default view. The default view in the 3D Graphics window, called the Home View, is an Earth-centered inertial position and direction. You can change the Home View and add other views in the 3D Graphics window using the 3D Graphics Toolbar. The ability to change the camera position and the view direction or camera reference point can be very helpful in analyzing a scenario. When you create and store a view, the view is a part of the scenario and can be utilized in any number of 3D Graphics windows that you open within the scenario. The following steps will guide you through the basics of setting and storing views in the 3D Graphics window.


2. Click View From/To on the 3D Graphics Toolbar.

3. In the Reference Frame section, select Earth Fixed Axes and click OK.

4. In the 3D Graphics window, rotate the view so that the White Sands facility is roughly centered.

5. Click Stored Views in the 3D Graphics window.

6. Click New to add the current view to the list of stored views.

7. Double-click the new view and rename it Fixed Axes.

8. Click OK.

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9. Animate the scenario again. Notice that this time the camera position remains fixed on the White Sands facility, revolving in sync with the Earth. Using this view we can observe the impact of our scenario on the White Sands facility for the entire period.

10. Reset the animation.


12. In the View From field, select the ERS1 satellite. The ERS1 satellite will also become highlighted in the View To field. Click OK.

13. Manipulate the view in the 3D Graphics window so that the surface of the Earth becomes visible beneath the ERS1 satellite.

14. Click Stored Views on the 3D Graphics Toolbar.

15. Click New to add the current view to the list of stored views.

16. Double-click the new view and rename it ERS1. Click OK.

17. Animate the scenario again. Notice that this time the view follows the ERS1 satellite as it orbits the Earth.


19. Use the Stored Views drop down to cycle through your images.

20. When you are finished cycling through the stored views, click Home View .

21. You can also change the view perspective by holding the shift key and double-clicking on an object on the 3D Graphics window. This will have the same effect as setting the view to and from the object by using the View From/To button.

22. Other important 3D Graphics Toolbar features include:

Viewpoint Control buttons Finer , Coarser , and Toggle . The Finer and Coarser Viewpoint Control buttons adjust mouse sensitivity from the default, while the Toggle Viewpoint Control button resets mouse sensitivity to the default.

View Pilot The View Pilot button launches a small control panel that allows you to make small, incremental adjustments to the view. If this option is not on your

3D Graphics window toolbar, click the Toolbar Options drop down ( ). Select Add or Remove buttons 3D Graphics. You will see the View Pilot option.

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Camera Control The Camera Control button is an advanced animation feature that is not covered in this tutorial.

Calculating Access

Now you will calculate access from the ERS1 satellite to the area target to determine whether the satellite can view any of the wreckage and help in the search efforts.

1. In the Object Browser, highlight ERS1, right-click the mouse, and select Access.

2. When the Access window appears, select SearchArea in the Associated Objects list and click Compute. Portions of the satellite's ground track are highlighted in the 2D Graphics window to indicate periods of access to the area target.

3. Now click Access in the Reports area to view an Access Summary Report. As you can see, there are several periods of access.

4. Close the report.

5. In the Access window, click the Remove Access button. Click Close.

Working with Sensors In this exercise you will first attach sensors to a satellite and experiment with sensor pointing types. Then you will attach a sensor to a ground facility and limit its visibility to objects a certain distance above the horizon.

Defining and Pointing Sensors

1. With the ERS1 satellite selected in the Object Browser, insert a sensor ( ) from the Object Catalog. Name the new sensor Horizon.

2. Launch the sensors Properties Browser, and open the Definition page.

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3. Make sure the Sensor Type is set to Simple Conic and the Cone Angle is 90 deg.

4. Select the Basic - Pointing page of the sensors properties.

5. You want to point the sensor straight down relative to the ERS1 satellite. To do this, verify that the Pointing Type is set to Fixed and Elevation is set to 90 deg.

6. Click OK.

7. Unclutter the 2D Graphics window a bit by removing the Shuttle's contour graphics. Open the 2D Graphics - Contours page for the Shuttle, turn off the Show option for Elevation Contours, and click OK.

8. In the first 2D Graphics window (2D Graphics - Earth), click the (Reset) button, and then click the (Animate Forward) button. Note the graphics representing the Horizon sensor's field of view (shown here zoomed).

9. Stop the animation by clicking (Reset) or (Pause).

10. Launch the sensors Properties Browser, and open the Definition page. Change the Cone Angle to 45 deg.

11. Open the 3D Graphics Attributes page and enable Translucent Lines.

12. Select 3D Graphics - Pulse.

13. In the Parameters frame, turn on the Show option.

14. Ensure the Amplitude is set to 0.5.

15. Set the Pulse Length to 2000 km.

16. Set the Frequency value to Slow.

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17. Set the Value to 0.083 Hz.

18. Click Ok.


20. In the View From field, select the ERS1 satellite. The ERS1 satellite will also become highlighted in the View To field. Click OK.

21. In the 3D Graphics window, adjust the view so that you can get a good look at the satellite in reference to the Earths surface, such as the following image depicts.

22. Animate the scenario and watch the sensors projection as the satellite travels along its orbit.


24. Bring up Horizons Properties.

25. Select the 3D Graphics Pulse page.

26. Disable Show in the Parameters section.

27. Open the Definition page.

28. Set the Cone Angle to 90 deg.

29. Click OK to dismiss Horizons Properties.


31. Add another sensor to the ERS1 satellite and name it Downlink.

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32. Open the new sensor's Definition page.

33. Select Half-Power as the Sensor Type

34. Set the Frequency to 0.85 GHz and the dish Diameter to 1.0 meter. STK computes the half-angle for you.

35. Open the Basic - Pointing page.

36. Change the Pointing Type to Targeted and the Boresight Type to Tracking.

37. Select the Baikonur facility in the Available Targets list.

38. Move ( ) Baikonur to the Assigned Targets list.

39. Repeat Step 15 for each facility until all the facilities appear in the Assigned Targets list.

40. Click OK.

41. Animate the scenario and let the animation run until the ERS1 satellite moves over the Santiago facility (shown here zoomed).

42. Click the (Reset) button to stop the animation.

Limiting a Sensor's Visibility

Now you will attach sensors to a couple of ground facilities and limit their visibility.

1. Attach a sensor to the Wallops facility and name it FiveDegElev.

2. Open the new sensor's Basic - Definition page.

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3. Set the Sensor Type to Complex Conic.

4. Set the Inner Half Angle value to 0 deg.

5. Set the Outer Half Angle value to 85 deg.

6. Set the Minimum Clock Angle to 0 deg.

7. Set and the Maximum Clock Angle to 360 deg.

8. Open the Basic - Pointing page, and make sure that the Pointing Type is set to Fixed and Elevation is set to 90 deg.

9. Open the 2D Graphics Projection page.

10. Set the Maximum Altitude to 785.248 km and the Step Count to 1.

11. Click OK.

12. You can reuse the new sensor. Highlight the FiveDegElev sensor in the Object Browser, and select Copy from the Edit menu.

13. Now highlight the WhiteSands facility in the Object Browser window, and select Paste from the Edit menu.

14. Open the 2D Graphics - Attributes page for the new sensor.

15. Set the Color to the same color of the WhiteSands facility. This will ensure the fields of view of the sensors attached to the WhiteSands and Wallops facilities are more clearly distinguishable.

16. Click OK.

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17. Click the (Reset) button if necessary to display the new color.

Static & Dynamic Display of Data The reporting and graphing capabilities of STK make it easy to display and analyze data developed during a scenario. Also, data that change over the scenario's time period can be displayed dynamically in the course of animation.

Reports & Graphs This exercise illustrates one of the many standard report and graph options that are shipped with STK.

Note: In addition to standard report and graph styles, STK makes it easy to create custom reports and graphs to suit your particular analytical or operational needs.

1. Highlight the ERS1 satellite in the Object Browser, right-click the mouse, and select the Report & Graph Manager.

2. Select Satellite as the Object Type.

3. Select ESR1.

4. Turn Off Show Graphs.

5. Select Solar AER from the Styles list.

6. Click Generate.

7. A report is generated, showing the azimuth, elevation, and range of the Sun with respect to the ERS1 satellite at one-minute intervals throughout the satellite's time period.

8. Close the report, but do not close the Report & Graph Manager.

9. Turn Off Show Reports.

31

10. Turn On Show Graphs.

11. Select Solar AER in the Styles window.

12. Click Generate.

13. The data that were previously presented in a report are now displayed in graph form.

14. To change the color and/or other properties of any of the graph elements, right-click on a graph element.

15. When the Report & Graph context menu appears, select Customization Dialog.

16. In the Customization Dialog window, make any desired changes to Color, Style, or any other graph property.

17. Click OK to dismiss the Customization Dialog window.

18. Close the Report & Graph Manager.

Dynamic Displays & Strip Charts STK provides two ways to display data dynamically while a scenario is animating: a dynamic display of report-style data, or a strip chart presenting data in graph style.

1. Open the Shuttle Properties.

2. Select 3D Graphics Data Display.

3. In the Data Display table, turn On the Show option for LLA Position.

4. Click OK.



7. In the View From field, select the Shuttle. The Shuttle will also become highlighted in the View To field.

8. Click OK.

9. A dynamic display appears, with entries for time, latitude, longitude, altitude, and corresponding rate data.

10. Animate the scenario. The Shuttle's positional and rate values will change as the animation progresses.

32

11. Pause the animation when the Shuttle is at or near its northernmost position in the 3D Graphics window. The displayed value for latitude should be in the vicinity of 28.5 deg. This corresponds to the Inclination that was set for the Shuttle when you defined its Orbit properties.

12. Click the (Reset) button.

13. Bring up the Report & Graph Manager.

14. Select Satellite as the Object Type.

15. Select Shuttle.

16. Ensure the Show Reports option is turned off.

17. Select Solar AER in the Styles Field.

18. Turn On Dynamic Display/Strip Chart.

19. Click Generate.

20. Position the strip chart window so that you can see it and the first 2D Graphics window simultaneously, and animate the scenario.

33

Note: Once the animation starts, graph elements will begin to appear on the graph. These graph elements can be modified by using the same procedure as for the graphs in the preceding section.

21. The strip chart shows azimuth, elevation, and range information from the satellite to the Sun. Note that the range (distance) varies over a span of about 11500 km, representing the difference between the positions in its orbit nearest to and most distant from the Sun.


23. Close the strip chart.

24. Click Close to dismiss the Report & Graph Manager window.

Setting Constraints In this section you will experiment with just two of the many ways in which STK allows you to constrain objects and thereby refine your analysis. In both cases you will impose constraints on the Horizon sensor attached to the ERS1 satellite.

1. Highlight the Horizon sensor (attached to the ERS1 satellite) in the STK Object Browser, right-click the mouse, and select Access Tool.

2. Select the Baikonur facility in the Associated Objects window, and click Compute.

Note: Do not dismiss the Access window.

If you view the 2D Graphics window, you will see the ground track of the ERS1 satellite has been highlighted to indicate periods of access between the ERS1 satellite and the Baikonur facility.

34

3. Now, with the Horizon sensor still highlighted in the Object Browser, launch the sensors Properties Browser, and select the Constraints - Sun page.

4. Turn on the Min(imum) option for Sun Elevation Angle, and set the value to 10 deg.

5. Ensure you have the 2D Graphics window in view so you can see the change immediately.

6. Click Apply, and note the change in access graphics in the 2D Graphics window.

7. Experiment with other values for Sun elevation angle, such as 0 deg, 5 deg, 15 deg, and 20 deg, clicking Apply each time to see the results.

8. Turn off the Min(imum) option for Sun Elevation Angle, and then open the Constraints - Basic page.

9. Turn on the Max(imum) option for Range, and set the value to 2000 km.

10. Click Apply, and observe the impact on access graphics in the 2D Graphics window.

35

11. Experiment with other values for maximum range, such as 1500 km, 1000 km, and 500 km, clicking Apply each time to see the results.

12. When you are finished, turn off the Max(imum) option for Range, and click OK to dismiss the Properties Browser.

13. Click the Remove Access button in the Access window, and then click Close to dismiss the window.

Creating a Walker Constellation Finally, you will become acquainted with a tool that allows you quickly to define and propagate a constellation of systematically spaced satellites with circular orbits having the same inclination and period. We will use the ERS1 satellite as a "seed" to generate the constellation.

1. Select the ERS1 satellite in the Object Browser window, launch its Properties Browser.

2. Open the Basic - Orbit page.

3. Change the Stop Time for the satellite to default start time + six (6) hours.

4. Click OK.

5. With the ERS1 satellite still highlighted, right-click the mouse and select Satellite Walker

6. In the window that appears, make certain that Delta is selected as the Type.

7. Set Number of Planes to 2.

8. Set Number of Sat(ellite)s per Plane to 3.

9. Set the Inter Plane Spacing to 1.

36

10. Ensure that RAAN Spread is set to 360 deg.

11. Ensure the Color by Plane option is turned on.

12. Uncheck Create unique names for sub-objects.

13. Click Create Walker.

14. Six new satellites appear in the Object Browser, each with an automatically generated name based on the name of the seed satellite. Each of the newly created satellites has two sensors with the same properties as those of the sensors attached to the seed satellite.

15. Close the Walker Tool dialog.

16. Click the (Reset) button, and animate the scenario.

17. Observe how the (targeted) Downlink sensor pattern appears in the 2D Graphics window as each satellite passes near a facility.


37

Conclusion This concludes the tutorial. But we barely scraped the surface. As you undoubtedly noticed while working through these exercises, for each properties page you opened, for each menu item you selected, for each option you tried out, and for each tool you used, there were many dozens we had to skip over. So, why not take another voyage through the tutorial, this time exploring some detours and browsing through some of the many properties pages, menus, and tools you find along the way?

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Analytical Graphics, Inc. (AGI) 1 of 11 STK Pro Tutorial

Introduction to the STK Pro tools

Overview

This tutorial will introduce the STK Pro tools by analyzing the line of sight communication links for a

ground survey crew in mountainous terrain.

Note: You will need a valid STK Pro license to complete this tutorial. This tutorial is designed for STK

users only.

Create a New Scenario

1. Launch STK.

2. Click the Create a Scenario button in the Welcome to STK window.

3. In the STK: New Scenario Wizard,

a. Name the scenario ProGroundSurvey.

b. The Description field allows you to provide a short summary of your scenario. That

description can be viewed in STK before loading a scenario. An appropriate description

would be Analyze line of sight links for a survey crew in mountainous terrain.

c. Accept all other defaults, and click OK.

4. STK will load a new scenario. In the foreground is the Insert STK Objects tool. Close it for now; it

will be used later. In the background STK window, the Object Browser is docked to the left side.

At the moment, it contains only the scenario object. Docked to the bottom of the STK window is

the Timeline View. Also displayed are the 3D Globe and 2D Map.

Define the Terrain Environment

Begin by defining characteristics of the local environment for the scenario. In this case, you will be

selecting a file that defines the local terrain geometry. The terrain file will be used by STK to compute

the position of ground based objects (Facilities and GroundVehicles) as well as the obstructions to Line

of Sight Access for all objects. With advanced RF analysis modules (Communications and Radar), terrain

can also be used to determine losses due to diffraction over terrain.

1. On the 3D Window Toolbar, click the Globe Manager button. This will open the Globe

Manager window, docked to the left side of the screen.

2. At the top of the Globe Manager window, click the Add Terrain/Imagery button.

3. From the Path dropdown, select the default STK textures directory:

\AGI\STK 10\STKData\VO\Textures

4. Ctrl-click to select the following two files:

St Helens.jp2 (Image)

St Helens.pdtt (Terrain)

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5. Click Open to load the terrain and imagery. When prompted to Use Terrain for Analysis, click

Yes.

Note: It is possible to use terrain for display only, but for this tutorial we will use terrain for

analysis as well (to define object position and line of sight obstruction).

Note: You may also check the box to Remember my choice and dont ask again so that all

terrain files loaded in the future will also be used for analysis.

6. In the Globe Manager, find the St Helens terrain and image items. Double click on either

entry to zoom to the region.

7. Right click on the St Helens.pdtt item and select Toggle Extents to highlight the region of the

globe covered by that data file. Repeat to remove the highlight.

Note: The Show Extents option is helpful for determining which file covers which region

when using multiple tiles in a single scenario.

Using Terrain to Define Object Properties

The ground survey crew we are modeling will consist of a monitoring station at a fixed location

overlooking the crater and a ground vehicle traveling across the North side of the mountain taking

measurements to send back to the monitoring station. The terrain file previously loaded will be

referenced by STK to define the altitude of these objects.

Insert the Monitoring Station

1. Launch the Insert Object tool to define the objects in the system.

2. From the Insert Object Tool, select the Facility object and Insert Default method. Click

Insert

3. Close the Insert Object Tool.

4. In the Object Browser on the left side of the screen, locate the new facility. Right-click the

facility, and rename it MonitorStation.

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5. Right-click the MonitorStation facility again and select Properties . The MonitorStation

Properties will open to the Basic > Position page. Specify the following position:

a. Latitude: 46.1907 deg

b. Longitude: -122.195 deg

c. Altitude: Check the box to Use terrain data.

Note: This option reads the terrain altitude at that location and inherits the value. If the

object is moved to a new location, the terrain altitude will automatically update.

d. Height Above Ground: 4 m

Note: This value defines the height of the analysis point above ground level. In this case, we

have a communications antenna mounted roughly 2 meters above the ground. This is

important when considering terrain obscuration.

6. Using the tree on the left side of the Properties window, select the 3D Graphics > Model page.

To change the Model file, click the ... button and select omni_directional_antenna.mdl.

7. Go to the 3D Graphics > Offsets page. Under Translational Offset, check the Use checkbox. For Z,

enter 4 m. This way, the 3D model position will reflect the Height Above Ground value set in the

previous steps.

8. Click Apply to accept your changes, then bring the 3D Window to the front.

9. In the Object Browser, right-click MonitorStation and select Zoom To. You may need to zoom in

further (right-click and drag downward on the 3D window) to get a good view of the small

antenna.

Build an Azimuth Elevation Mask

An Azimuth Elevation Mask is an analytical utility that evaluates the minimum elevation at which line of

sight is obscured by terrain in all azimuth directions from a specific location. The mask can then be

applied as a Constraint to limit access availability. This mask can also be visualized in the 3D window to

provide an intuitive understanding of where terrain will block access.

1. In the MonitorStation properties, select the Basic > AzElMask page.

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a. Select Use Terrain Data.

b. Check the box to Use Mask for Access Constraint.

c. Click Apply to accept the changes.

2. Go to the 2D Graphics > AzElMask page.

a. Check the Show box in the At Range section.

b. Number of Steps: 6

c. Minimum Range: 0 km

d. Maximum Range: 5 km

3. Click OK to accept your changes and see the resulting mask drawn in the 3D window.

Insert the Survey Crew

Create a ground vehicle that will traverse the North side of the mountain face (where the rim of the

crater is lowest). After some initial set-up, you will use the 3D Object Editor to quickly add points to a

route. Again, the terrain file will be referenced by STK determine the altitude of the vehicle as it follows

a ground path.

1. From the Insert Object tool, select the Ground Vehicle object and Define Properties

method. Click Insert

2. On the Basic > Route page, in the Altitude Reference section, specify the following to make the

vehicle follow the loaded terrain:

a. Reference: Terrain

b. Granularity: 10 m

c. Interp Method: Terrain Height

3. Go to the Constraints > Basic page and check the box for the Terrain Mask constraint.

4. Click OK to accept the terrain following and masking properties.

5. Rename the ground vehicle MeasurementCrew.

6. To define the route using the 3D Object Editing technique, first locate the 3D Object Editing

toolbar:

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Note: If the 3D Object Editing toolbar is not shown, go to View > Toolbars and select 3D

Object Editing

a. Select the GroundVehicle/MeasurementCrew object from the 3D Object Editing dropdown.

b. Click the Object Edit Start/Accept button.

c. Shift-click on the 3D Globe to add waypoints to the route.

d. Continue to Shift-click in multiple locations, creating a route that has multiple passes across

the North face of the mountain.

e. Click the Object Edit Start/Accept button to save the changes to the route.

Using a Targeted Sensor and Terrain Mask Access Constraint

A sensor object will be used to represent the field of view for a data transmitting antenna on the

MeasurementCrew vehicle. Using this representative field of view, STK will determine the times when

the Ground Crew can transmit data to the Monitor Station and the times when terrain obscures the line

of sight between those objects. With the STK Communications module, an actual antenna gain pattern

can be applied and signal losses computed between a transmitter and receiver to determine access

availability and link budget.

1. From the Insert Object tool, select the Sensor object and Define Properties method.

Click Insert

2. In the Select Object window, choose the MeasurementCrew ground vehicle as the sensors

parent object and click OK.

3. Rename the sensor DataTransmitter.

4. On the Basic > Definition page, specify a Cone Half Angle of 5 deg.

5. On the Basic > Pointing page, change the Pointing Type to Targeted. Under Available Targets,

select the MonitorStation object. Click the right arrow to move it to the Assigned Targets list.

6. Click OK to accept the changes and dismiss the window.

7. In the Object Browser, right click on the DataTransmitter Sensor and select Access

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8. From the Access Tool, select the MonitorStation object, then click the Access button under

Reports.

a. If your report says No Access Found, return to the Insert the Survey Crew section and

add a few more points to your route, focusing on the North face of the mountain.

b. If your report lists Access Intervals, right-click on one of the Start Times in the report. From

the Start Time menu, select Set Animation Time. When you look back at the 3D window,

you will see the animation has advanced to the beginning of the Access interval. Note the

position of the vehicle with respect to the facility terrain mask.

Introducing Constellations and Chains

Now let us suppose that you wish to relay the data collected by the ground crew to other interested

parties across the country. One option for this task is the Globalstar satellite communication system.

The Globalstar network relies on Gateway locations to connect relayed signals to terrestrial

phone/data lines. The closest Globalstar Gateway to Mount St. Helens is in High River, Alberta.

First, we will bring all the new objects into our scenario, then we will integrate those new objects into

our analysis using Constellation and Chain objects. A Constellation is a single STK object that represents

a group of other STK objects in the scenario. Once grouped in a Constellation, the constellation can be

treated as a single object for analysis. This allows the users to perform complex access calculations from

one object to many objects, many objects to many objects, or a series of links (multiple hops between

single objects or groups) required to fulfill a single Access.

Insert the Globalstar Constellation

1. From the Insert Object tool, select the Satellite object and the From Standard Object

Database method. Click Insert

2. Select the Local tab.

Note: The Online tab pulls objects from the AGI Standard Object Database. This is a compilation

of publicly available data about various platforms and their payloadswhich is more

information than we need for this exercise. The Local tab pulls in position data only. If an

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Internet connection is available, it will attempt to pull in the most recent position data available.

Otherwise, it will use locally cached position data.

3. For Common Name, enter Globalstar, then click Search.

4. Shift-click or Ctrl-A to select all results (there should be approximately 50).

5. Check the Create Constellation from Selected Satellites checkbox.

Note: In this example, our MonitorStation only needs a single Globalstar satellite available to

send data, but any satellite from the Globalstar network will suffice. Using a Constellation

object, we can provide that layer of abstraction.

6. In the Name field, enter Globalstar.

7. If you do not have internet Access, click the Modify button, then select the Import from File

radio button, and click OK.

8. Click Insert to import the Constellation of satellites; then click Close.

Insert the High River Ground Station

STK provides a database of city locations for easy importing of a Place object.

1. From the Insert Object tool, select the Place object and the From City Database

method. Click Insert

2. Enter High River for the City Name and click Search.

3. Select the High River, Alberta, Canada result and click Insert.

Build a Communication Chain

The Chain object will evaluate the available communication paths from the ground crew collecting data

to the Globalstar Gateway by first defining, then evaluating each step in this multi-hop system. The

series of links would start with the ground crew, go through the DataTransmitter to the Monitor Station,

then onto the Globalstar constellation (using any available satellite from the collection) and finally to the

Gateway at High River. Taking the entire system into account, the Chain object will evaluate the

availability of each link and report when all links are simultaneously available.

1. From the Insert Object tool, select the Chain object and the Define Properties method.

Click Insert

Note: A Chain object performs the same calculations as Access but allows users to string

together multiple links in a chain or to substitute a single link in the chain with a

Constellation of available objects. The resulting Chain is satisfied only when all individual

links are available.

2. Rename the Chain DataTransmission.

3. On the Basic > Definition page of the DataTransmission Chain properties, select each of the

following objects and right-arrow them into to the Assigned Objects list in this order:

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MeasurementCrew

MonitorStation

Globalstar

High_River

4. Click OK to accept the Chain properties.

5. In the 3D Window, zoom out until you can see all parts of the system: Mount St. Helens, High

River, and the Globalstar satellites. Observe the various lines connecting the St Helens region to

the satellites and then to the High River location these lines indicate all possible

communication paths for the signal.

Note: If you dont see the chain graphics, right-click on the DataTransmission chain, select

Report & Graph Manager, then under Installed Styles, choose Complete Chain Access and

click Generate. This report lists all the times that the chain is completed. Set the animation to

one of those times, and the chain graphics should appear.

6. In the Object Browser, right-click on the DataTransmission Chain and select Report & Graph

Manager

7. From the Installed Styles, select the Individual Strand Access graph and click Generate

a. This graph shows the periods of time where each strand is available. A Strand is a single

path that the signal could travel along. Note that there are many satellites to choose from,

each providing different intervals of coverage for the system.

b. If all the data is bunch up against the left side, the time interval is too large for the data set

that you wish to show. Towards the top of the graph window, where it says Interval, click

the down carat button. Select Replace With Times, then enter +1 hr for the Stop time.

Hit the F5 key or the Refresh button to see the new graph. Continue to adjust the Stop

time until you are satisfied.

8. Go back to the Report & Graph Manager. Generate the Individual Strand Access report.

From this report, you should be able to determine the single Globalstar satellite that provides

the longest duration of communication between the MeasurementCrew and High_River.

9. When you are finished with them, close the graph, report, and the Report & Graph Manager.

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Create a Sensor Mask Using STK Pro Object Tools

Perhaps instead of a ground crew collecting measurements, an Unmanned Ariel Vehicle (UAV) is

collecting data with a forward looking sensor. The Complex Conic sensor type allows users to define

sensor patterns, using Inner and Outer Half Angles to define cone radially, and Clock Angles to carve out

sections of the cone. On top of that, we want to account for any portion of the sensor cone that is

blocked by the body of the UAV itself.

Insert the UAV

1. From the Insert Object tool, select the Aircraft object and Define Properties method.

Click Insert

2. Rename the aircraft Hunter_UAV.

3. In the properties, on the 3D Graphics > Model page, change the model file to rq-

5a_hunter.mdl.

4. Click OK to dismiss the Properties panel.

5. Use the 3D Object Editor to define the path of the Aircraft.

a. From the 3D Object Editor toolbar dropdown, select Aircraft/Hunter_UAV.

b. Click the Object Edit Start/Accept button.

c. Use Shift-click to add waypoints to a route that traverses the region of terrain multiple

times.

d. Click the Object Edit Start/Accept button to save the route.

Model the Sensor

This UAV is equipped with a forward-looking collection sensor that can rotate 70 degrees left or right,

and from 60 degrees downward to 20 degrees upward (relative to the Body Axes of the aircraft).

1. From the Insert Object tool, select the Sensor object and Define Properties method.

Click Insert

2. In the Select Object window, select the Hunter_UAV aircraft as the parent object, and click OK.

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3. Rename the sensor ForwardLooking.

4. On the Basic > Definition page, specify a Sensor Type of Complex Conic with the following

parameters:

Inner Half Angle: 30 deg

Outer Half Angle: 110 deg

Minimum Clock Angle: -70 deg

Maximum Clock Angle: 70 deg

5. On the Constraints > Basic page, under Range, check the Max checkbox. Enter 5 km.

6. The rq-5a_hunter.mdl model has been built with Attach Points that provide a convenient

location to mount a sensor. To use the attach point as the mounting location of the sensor:

a. On the Basic > Location page, set the Location Type to 3D Model.

b. On the 3D Graphics > Vertex Offset page, uncheck the Inherit from Parent Object. Under

Attach Point check the Use checkbox. Select the camera_lens-000000 attach point.

c. Click OK

7. Check the results in the 3D Window by zooming to the Hunter_UAV. Note that the sensor is

attached to the payload location on the aircraft body.

Create a Sensor Mask

With the forward-looking sensor, the landing gear and front portion of the fuselage are within the field

of view. STK provides an Azimuth/Elevation Mask tool that will evaluate the geometry of the 3D model

specified for the parent object of the sensor (in this case, the Hunter UAV model) to create a mask file

(similar to the Terrain mask) that shows where the model geometry obstructs visibility from the sensor.

1. Right click on the ForwardLooking Sensor, choose the Sensor menu item and select the AzEl

Mask tool.

a. From the Obscuring Objects list, select only the Hunter_UAV Aircraft object

b. Next to File, click the button to select a location for the resulting Body Mask File. Enter

ForwardMask as the file name and click Save.

c. Click Compute.

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d. Click Apply and then Close. Also close the Az/El Mask View window that was created.

2. Open the Properties of the ForwardLooking sensor, and go to the Basic > Sensor AzEl Mask page.

a. Set the Use type to MaskFile, then browse to the ForwardMask.bmsk file you just

generated.

b. Check the box to Use Mask for Access Constraint.

c. Click the Apply button.

3. To setup the display of the mask, go to the 2D Graphics > Projection page.

a. In the Field of View section, check the Use Constraints checkbox.

b. From the available constraints, scroll down and select SensorAzElMask.

c. Click OK.

4. Note the changes to the field of view of the ForwardLooking sensor. This masked field of view

will be used for any STK calculations involving the ForwardLooking sensor.

Doing Things With Vectors

CONTENTS INTRODUCTION...................................................................................................... 1 USING VECTORS IN 3D VISUALIZATION..................................................................... 2

Vector Graphics ........................................................................................... 2 Displaying Vectors........................................................................................ 3 Planes........................................................................................................ 5 Creating a New Vector .................................................................................. 7 The Attitude Sphere ................................................................................... 11 Creating & Displaying Angles ....................................................................... 13 Persistent Vector Display............................................................................. 16

Introduction The following exercise is designed to introduce you to some of the ways in which you can use vectors in Satellite Tool Kit (STK) for the 3D visualization of vehicle attitude, sensor pointing and other phenomena of interest. You will learn to configure and use, among other things, the vector-related 3D Graphics properties of a satellite, the Attitude Sphere, the 3D Attitude Graphics window, and the Vector Geometry Tool.

License(s) Needed

The exercise below works best if you are licensed for the STK/Attitude module. However, you can do the exercise without an STK/Attitude license if you are

licensed for the STK Professional Edition. In the latter case, the Attitude Sphere will be unavailable, and you will need to use the 3D Graphics window for

display of vectors.

Create a Scenario, set its Epoch and Start time to 1 Jun 2002 12:00, and set its Stop time to 24 hours later. Click the Reset button to set the animation time to 1 Jun 2002 12:00.

Add a Satellite to the Scenario and, using the Orbit Wizard, define a Molniya orbit. After finishing with the Orbit Wizard, open the Orbit page of the Satellite's Basic properties and change the value for Inclination to 90 deg.1

1 This is a quick way to define a non-circular, polar orbit, which is helpful in illustrating some of the vector relationships discussed below.

2 Doing Things with Vectors

Using Vectors in 3D Visualization It is now time to try out some of STK's features and tools related to the definition and display of vectors. The following exercise demonstrates how you can visualize the differences among vectors defined in different reference frames.

Vector Graphics STK is shipped with a great variety of vectors and related componentsaxes, points, coordinate systems, angles and planesthat can be attached to objects and displayed in 3D. Highlight the Satellite in the Object Browser and open the Vector page of its 3D Graphics properties:

The upper left portion of the page contains a list of vectors and other components that can be displayed with the Satellite. Select the Velocity Vector in the list, check the Show option, check the Show Label option (if it is not already checked), and select a new Color if the current one will not show up well against a black background.

The velocity vector that you have selected is defined in a Central Body Inertial (CBI) reference frame. The above list does not include a velocity vector defined in a Central Body Fixed (CBF) Frame. However, a Velocity(CBF) vector is available. Click the Add button:

Doing Things with Vectors 3

Find the Velocity(CBF) in the Available column in the Add Vector Geometry Components window, select it and click the right arrow to move it to the Selected column (or simply double-click Velocity(CBF) to move it). Click OK to return to the Vector page.

Since you have added the new vector to the list, STK assumes that you want to display it. Therefore, the Show option for the Velocity(CBF) vector is already checked. Change the Color if you wish, and check the Show Label option if it is not already checked.

Click Apply and leave the Vector page open.

Displaying Vectors Now let's take a look at those vectors. Highlight the Satellite in the Object Browser, right-click the mouse, and select Satellite New 3D Attitude Graphics Window.2 The following window will appear:

2 If you are not licensed for STK/Attitude, see the instructions beginning on page 6.


Note

The 3D Attitude Graphics window is shown here with a white background to make it more printer-friendly. The window should look much better on your

computer screen.

Place the mouse pointer in the window, hold down the right mouse button and drag the mouse toward you to zoom in on the satellite. Hold down the left mouse button and move the mouse back and forth to rotate the satellite into the desired perspective:

Now animate the scenario and observe as the two vectors you defined separate, reflecting their differing reference frames (CBF and CBI):


Planes Before learning how to create vectors and other geometric components, lets take a look at another visualization aid that STK provides, namely, planes. Return to the satellites Vector page, and find the BodyXY Plane in the list of available components. Click the Show button to display the plane. Change the Color of the plane if you wish, check the Translucent Plane option and set Translucency to 70. Click Apply and return to the 3D Attitude Graphics window:

Before proceeding to the next section, return to the Vectors page, turn off the Show option for the plane and click OK.


What if I Don't Have an Attitude License? Skip this section if you are licensed for STK/Attitude. If not, you can configure the 3D Graphics window to behave in some respectsbut not all!like a 3D Attitude Graphics window. In the 3D Graphics window, if necessary expose the 3D Graphics Toolbar, and then:

1) Click the (View From/To) button.

2) In the window that appears, select the satellite of interest in the View From and View To columns.

3) Make certain that ICR Axes is selected as the Reference Frame.

4) Click OK.

There are further steps you can take, if you wish, to simplify the view. Click the (Properties) button and make some or all of the following changes: Open the Celestial page and turn off display options for Stars. Open the Grids page and turn off grid display options. To remove the orbit track, open the Pass page of the satellite's 3D Graphics properties, and in the Orbit Track frame, set Lead Type to None, and set Trail Type to None or to Same As Lead.


Note

Even with all this work (which has to be done for each satellite in the scenario that you want to view in this way), you do not achieve the full advantage of having the 3D Attitude Graphics window option available. For example, 3D

Attitude Graphics windows are ideal for making side-by-side comparisons of satellites having identical orbits but differing in attitude. Each satellite appears alone in its 3D Attitude Graphics window. In the 3D Graphics window, on the

other hand, the satellites appear superimposed on each other.

Creating a New Vector The vectors with which you have worked thus far in this tutorial are standard with STK (assuming you are licensed for the appropriate modules). Now let's create a new vector. Highlight the Satellite in the Object Browser, right-click the mouse, and select Utilities Vector Geometry Tool. A Vector Geometry Tool window appears:


If you select a vector or other component in the Components list, its properties are displayed in the right portion of the window.

The new vector you will create will be a velocity vector with the satellite body as its

frame of reference.3 Click the (Create New Vector) button. In the Add Vector window, select Derivative as the Type:

Under the Vector field, click the Select button:

3 Recall that the two vectors already being used in the scenario are also velocity vectors, but with CBI and CBF reference frames.


Highlight Velocity to select it as the reference vector, and click OK to dismiss the Select Reference Vector window. In the Name field of the Add Vector window, enter Velocity(Body), and click OK to dismiss the window. The new vector appears in the Components list in the Vector Geometry Tool window:


Click Close to dismiss the Vector Geometry Tool, and open the Vector page of the satellite's 3D Graphics properties. Click the Add button and add the newly created Velocity(Body) vector, using the procedure you used when you added the Velocity(CBF) vector. On the Vector page, select the new vector, check the Show Label option (the Show option is already checked), change the Color if necessary, and click Apply.

The new vector now appears in the 3D Attitude Graphics window (shown here after zooming and rotating the satellite and animating the scenario):


The Attitude Sphere If you are not licensed for STK/Attitude, proceed to the next section. If you do have an Attitude license, open the Attitude Sphere page of the satellite's 3D Graphics properties:

Check the Show option, click Apply, and look at the 3D Attitude Graphics window:


Now return to the Attitude Sphere page and consider some of the display options presented there:

The Sphere Color and Grid line width options control the appearance of the grid lines defining the sphere.

Use Zero Deg Color and Zero Deg line width to set off the equator and prime meridian lines as desired.4

Label Type and Label Color determine the display of latitude/longitude labels on the sphere.5

The Scale entry is a logarithmic value controlling the size of the sphere. The Frame field lets you select a reference frame for the sphere display.

You may want to take a few minutes and experiment with these and other settings and observe the impact on the display in the 3D Attitude Graphics window.

The Projections area of the Attitude Sphere page lets you control the display of central body limbs (projections), among other things, on the surface of the sphere.

The purpose of this exercise is not to demonstrate the many ways in which the Attitude Sphere might be useful in performing analytical or operational tasks, but merely to point to this capability and encourage you to explore it yourself. Basically, the Attitude Sphere is a representation of your reference frame, which may make it easier at times to understand the velocity, position or attitude of an object.

For example, you can use projections on the Attitude Sphere to help you analyze the velocity of a satellite relative to other bodies, such as the Earth. In the Projections frame, select Earth and check the Volume option. Click Apply. The Earth's projection will now display as a cone in the 3D Attitude Graphics window:

4 Equator and prime meridian (and other latitude/longitude lines) are defined here, of course, with respect to the coordinate system defined by the center of the satellite body and the selected reference axes. 5 See note 4.


If you animate the scenario and then pause it at apogee, the Earth-defined vectors (Velocity and Velocity(CBF)) will appear at approximate right angles to the Earth projection cone, as would be expected:

When you are finished, turn off the Show option on the Attitude Sphere page (near the top), and click Apply.

Creating & Displaying Angles Vectors comprise only one of six available component types that STK makes available. The others are axes, points, coordinate systems, angles and planes. In this exercise you will add some angles to the 3D display.

Return to the Satellites Vector page and click the Add button. The angle you are going to add needs to be created, so click the Launch Vector Geometry Tool button.


In the Vector Geometry Tool window, click the (Create New Angle) button. In the Add Angle window, make certain that Between Vectors is selected as the Type:

Click the Select button under the From Vector field, select the Velocity vector, and click OK. In the same manner, select Velocity(CBF) as the To Vector:


Enter a name in the Name field, and click OK to return to the Vector Geometry Tool window. Dismiss that window by clicking Close.

The newly created angle will appear in the Available column in the Add a Vector/Axes window. Move it to the Selected column, and click OK. On the Satellites Vector page, select the new angle and make certain that the Show Label option is unchecked. Check the Show Angle Value box and, if necessary, change the Color. Click Apply.

Look at the 3D Attitude Graphics window. Animate the scenario and observe the changes in the angle value as the vectors defining it move apart and back together:


Now that you know how to create and display angles, try adding another one: between the Velocity vector and the Velocity(Body) vector. Click the Add button and proceed as you did above. When you finish, click Apply, go to the 3D Attitude Graphics window, and animate:

Persistent Vector Display Before beginning this last exercise, lets simplify the display a bit. On the Vector page, uncheck the Show option for the Velocity(Body) vector and both angles. For the Velocity and Velocity(CBF) vectors:

1) Uncheck the Show Label option.

2) Click the ellipses () button next to the Axes field and select J2000 reference axes.

3) Draw at Point should indicate Satellite Center


4) Check the Show option for Persistence, enter a Duration of 1 day (86400 sec), select Sweep as the Connect option, and check the Fade box.

Click Apply and go to the 3D Attitude Graphics window. If necessary, expose the 3D Graphics Toolbar. Click the (View From/To) button. In the window that appears, in the View From column, open the Vectors folder and select Velocity. Select Inward in the View To column and click OK. Animate the scenario.


Rotate the view as necessary to see a flat disk and a warped disk. The flat disk represents the movement history of the Velocity vector, defined in a CBI frame. The warped disk represents the movement history of the Velocity (CBF) vector. As you may recall, the satellite you created at the beginning of this tutorial has a polar orbit. On the descending side of its orbit its motion relative to the rotating Earth is in the opposite direction to its motion on the ascending side. The motion of a vector defined in a CBF framework will reflect this difference.

Working with the Communications Antenna Object in STK

CONTENTS OVERVIEW................................................................................................................ 2 EMBEDDED ANTENNA VS. LINKED ANTENNA ................................................. 2 SET UP YOUR SCENARIO ....................................................................................... 2

Add a Facility and a Satellite .................................................................................. 3 Adding an Antenna and Receiver to the Facility...................................................... 3 Adding an Antenna to the Satellite.......................................................................... 4

GENERATING A REPORT ....................................................................................... 5 Access Report to Antennas ..................................................................................... 6

Communication Antennas in STK 2

Overview The Communications module has a new antenna object. In previous versions, users had to set receivers and transmitters, and then set antenna parameters on each (receiver or transmitter). This becomes tedious when you have many objects and many antenna objects.

With a new antenna object you can set the antenna properties once and then link to the antenna when it is used by a receiver and transmitter. In this tutorial, you are going to set up a scenario and use the new Communications antenna object. You will also learn the difference between the embedded antenna object and the linked antenna object.

AGI recommends that you go through the Pro Tutorial first. The Pro Tutorial helps you to become familiar with STK and how it works.

Licenses Needed:

This tutorial requires that you be licensed for the STK Professional Edition and STK/Communications.

Embedded Antenna vs. Linked Antenna There are two ways to use antennas in STK: an embedded or linked antenna. The embedded antennas are usually attached to a parent object like a receiver and/or transmitter. These antennas are specific to their parent object. This means that they cannot be used by multiple objects.

The linked antennas are independent of any receiver or transmitter and thus facilitate the sharing of the antenna by several transmitters and receivers. If you have multiple transponders attached to communication GEO satellite, you can create an antenna object and have the transmitters or receivers reference it. This is convenient when you have to change the properties of the antenna, because you only have to change the properties of one antenna, rather than changing the properties of multiple antennas.

Set Up Your Scenario Before you begin analyzing communication antennas, you will need to set up a simple scenario to provide context for your work.

Note: You will notice that when you save the scenario, a separate folder with a name similar to the scenario, is created. This will ensure that you do not accidentally overwrite your previous work.

1. Create a scenario.

2. When the STK: New Scenario Wizard appears, name it CommAntenna.

3. Leave the default scenario time.

4. Click OK.

Communication Anten

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STK Tutorial