Coverage

In this exercise you will learn to use two objects from the Coverage module - the coverage definition object and the figure of merit - to define and evaluate the coverage of a region, using available coverage assets.

Note: You will need a valid license for STK Professional Edition and STK/Coverage.

Define the Coverage Region and Assign Assets

Define a coverage region in the tropics, and compute its coverage by two satellites:

  1. Create a scenario, and name it Coverage.
  2. Using the Orbit Wizard, create a satellite with a Circular orbit, an Altitude of 400 km, and an inclination of 97.3 deg. Name it PolarSat.
  3. Create another satellite with a Circular orbit, and name it Shuttle. Open its Orbit page, change its RAAN to 340 deg, and click OK.
  4. Double-click the icon in the Object Catalog to add a coverage definition to the scenario. Name it Tropics.
  5. Open the Basic - Grid page for the coverage definition, and set the following options:
  7. Open the Assets page. Multi-select the two satellites, click Assign, make sure that Status is set to Active, and click Apply.

  8. Tip: To multi-select the satellites, click one satellite, hold down the Ctrl key, and click the other satellite.

  9. Open the 2D Graphics - Attributes page, and set the following options:
  11. Click OK, then select the coverage definition in the Object Browser, select Compute Accesses from the CoverageDefinition Tools menu, and observe the results in the 2D and 3D Graphics windows.
  12. Open the Report & Graph Manager for the coverage definition, and create a Coverage by Asset report. Which satellite achieved a higher average coverage of the tropics region?
  13. Create a Coverage by Latitude graph. Was coverage better or worse near the Equator?

Assess the Quality of Coverage with a Figure of Merit

Determine opportunities for dual coverage of the tropics region:

  1. Select the coverage definition in the Object Browser, and double-click the icon in the Object Catalog to add a figure of merit. Name it TwoEyes.
  2. Open the Definition page for the Figure of Merit. Choose N Asset Coverage for the Type, set the Compute field To Maximum, and click OK.
  3. On the 2D Graphics - Attributes page for the coverage definition, uncheck the Show Regions and Show Points options, and click OK.
  4. Open the 2D Graphics - Attributes page for the figure of merit, and set the following options:
  6. Click OK, and animate the scenario. The points that are highlighted at any time during the animation are the points that have access to either or both of the satellites at that time.
  7. Now open the Definition page for the figure of merit again. Enable the Satisfaction option, set Satisfied if to At Least, and set the threshold to 2. Click OK.
  8. The 2D Graphics window will immediately reflect the reduction in the amount of the coverage region that satisfies the 'at least 2' criterion. Animate the scenario, and note that points are highlighted only where the coverage of the two satellites overlaps.
  9. Open the 2D Graphics - Attributes page for the figure of merit. Uncheck the Show option for Static Graphics, and click Apply.
  10. Open the Contours page, set the Contours Type to Animation, and check the Show option. Make certain that Color Method is set to Explicit, then assign colors to each of the two levels in the Level Attributes list. Click OK
  11. Animate the scenario, and note that points are highlighted in one color when they are covered by only one satellite and in another color when they are covered by both satellites.
  12. Open the Report & Graph Manager for the figure of merit, and create a Satisfied by Time report, which summarizes the percentage and true area of the grid that satisfies the figure of merit over time.