Compute Accesses Tool

The ultimate goal of coverage is to analyze accesses to an area using assigned assets and applying necessary limitations upon those accesses. Several tools are available to the coverage definition object () that will assist you in computing, reloading, clearing, and exporting access calculations. Accesses can only be computed for a coverage definition; figures of merit are extensions of the coverage definition object and, as a result, obtain their access information from their parent coverage definition. The Compute Accesses tool allows you to compute accesses between the grid points and the assigned assets.

To open the Compute Accesses tool, highlight the coverage definition object in the Object Browser and select Compute Accesses from the CoverageDefinition menu.

The menu item Compute Accesses in Parallel displayed in the CoverageDefinition menu. More information on computing accesses in parallel can be found in the STK Parallel Computing Help.

You can set STK so that the status of the access computations displays in the 2D Graphics window while accesses are being calculated. Regardless of whether progress graphics display in the 2D Graphics window, a progress indicator, which allows you to interrupt access computations, displays. If you interrupt access calculations (by clicking the Interrupt button on the Progress indicator) or add a new asset to the coverage area, use the Compute Accesses tool again to complete the access calculations and account for any changes in the coverage definition.

You can also use the Interrupt function to evaluate partial results based on the data accumulated up through the last completed grid level. This is a time-saving feature that can be valuable when there are a large number of assets.

If the Automatically Recompute Accesses option is selected on the Advanced page, accesses are recomputed every time changes are made that affect assets or the definition of the coverage grid.

Performance

Follow these steps to speed up coverage computations for a satellite by transforming the inertial coordinates to fixed before performing the coverage computation:

1. Export the satellite's ephemeris, using the fixed coordinate system for the appropriate central body. (The Export->Ephemeris/Attitude tool is available from the Utilities menu.)
2. Change the satellite's propagator to StkExternal, and use the ephemeris file you just exported.
3. Compute coverage by selecting Compute Accesses from the CoverageDefinition menu.