Advanced Options for a Chain

The Advanced page for a chain enables you to set the following properties:

Category Option Description
Compute Time Period Use Object Time Periods The Time Period that you set for objects in the chain is used to compute access. For facilities and targets, the scenario Time Period is used.
Use Scenario Time Period The Time Period that you defined for the scenario is used to compute access.
User Specified Time Period Specify the Interval or Start and Stop times for access computation. For more information on the options available for intervals and start and stop times, see Time Options.
Strand Access Intervals File Create If you select this check box, access computations are used to produce an .int file containing the strand access intervals.
Access Automatically Recompute Accesses

If you select this check box, STK automatically recomputes accesses each time that an object on which the chain depends is updated.

Accesses are recomputed when definition changes occur, but not when changes merely involving 2D and 3D graphics occur.

Access Save Mode Don't Save Accesses Access computations are not saved with the chain.
Don't Save, Compute on Load Access computations are not saved with the chain, but they are recalculated each time that the chain is opened in STK.
Save Accesses Access computations are saved with the chain.
Compute Options Use Light Time Delay Enables light time delay.

Setting this option will significantly increase the time it takes to compute access.

Access Options... Click to specify event detection and step size control parameters.
Constellation Constraints Apply constraints across all strands in a constellation

When constellations are used in a chain, apply constraints across valid strands, not individual objects in the constellation.

For example, a chain that contains the following will have valid times when any two of the satellites have visibility to any of the places.

  • a constellation of three satellites with a From constraint of At Least 2

    and

  • a constellation of two place objects with a To constraint of Any of
Apply constraints to each object in a constellation

When constellations are used in a chain, apply constraints to individual objects in the constellation.

For example, a chain that contains the following will have valid times for the chain when any of the satellites have simultaneous visibility to two of any the places.

  • a constellation of three satellites with a From constraint of At Least 2

    and

  • a constellation of two place objects with a To constraint of Any of
Chain as a Coverage Asset Append Grid Object to End of Chain When a chain object is used as a coverage asset, STK adds each grid point to the end of the chain during access computations for that grid point.
Update Grid Object in Chain When a chain object is used as a coverage asset, STK updates the chain's intervals as each grid point is evaluated during access computations for that grid point. The coverage grid instance specified must be an object used in the chain.

If the object's time period is shorter than the time period that you set here, accesses are computed only for the object's time period. STK does not extrapolate beyond the object's time period.