Access Separation

Access Separation detects periods of time when grid points have two or more access intervals within a specified time range of each other. This topic describes:

how to set access separation parameters
displaying access separation figure of merit (see Displaying Access Separation in a Graphics Window)

Setting access separation parameters

You must specify the requirements for the separation between accesses and as well as the criteria for figure of merit satisfaction. Use the parameters described in the following table:

Required parameters for Access Separation

Option	Description
Minimum	This is the minimum required separation time between coverage intervals. If you specify a nonzero value, the end of the leading interval and start of the trailing interval must be separated by at least this amount for STK to detect a satisfaction event. This applies regardless of your choice for Satisfaction Inteval Type.
Maximum	This is the maximum separation time between when visibility occurs in the leading interval and when visibility occurs in the trailing interval. If the time between the end of the leading interval and start of the trailing interval exceeds this amount, STK cannot derive any satisfaction interval from that pair of access intervals.
Satisfaction Interval Type	Choose the method to use for determining how STK reports figure of merit satisfaction intervals. Select from the following options: Single: Satisfaction is met for all times between the moment within the leading interval when the maximum separation constraint is met until the last moment within the trailing interval when the maximum separation constraint is met. This is inclusive of any gap period between the leading and trailing intervals. STK reports a satisfaction interval for the period of time when these conditions are met. The reported interval contains both leading and trailing visibility periods. Broken: Satisfaction is met starting the moment within the leading interval when the maximum separation constraint is met until the last moment within the trailing interval when the maximum separation constraint is met. This is exclusive of any gap period between the leading and trailing intervals. Required conditions were met at all times during the reported interval. The reported interval contains both leading and trailing visibility periods. Leading: Satisfaction is met at times between the moment within the leading interval when the maximum separation constraint is met until the last moment within the leading interval when the maximum separation constraint is met. Required conditions were met at all times during the reported interval. The reported interval contains only times within the leading visibility period. Trailing: Satisfaction is met at times between the moment within the trailing interval when the maximum separation constraint is met until the last moment within the trailing interval when the maximum separation constraint is met. Required conditions were met at all times during the reported interval. The reported interval contains only times within the trailing visibility period. The selected definition does not affect whether or not STK detects a satisfaction event, but it does affect the interval of time over which STK considers the FOM to be satisfied.

Option

Description

Minimum

This is the minimum required separation time between coverage intervals. If you specify a nonzero value, the end of the leading interval and start of the trailing interval must be separated by at least this amount for STK to detect a satisfaction event. This applies regardless of your choice for Satisfaction Inteval Type.

Maximum

This is the maximum separation time between when visibility occurs in the leading interval and when visibility occurs in the trailing interval. If the time between the end of the leading interval and start of the trailing interval exceeds this amount, STK cannot derive any satisfaction interval from that pair of access intervals.

Satisfaction Interval Type

Choose the method to use for determining how STK reports figure of merit satisfaction intervals. Select from the following options:

Single: Satisfaction is met for all times between the moment within the leading interval when the maximum separation constraint is met until the last moment within the trailing interval when the maximum separation constraint is met. This is inclusive of any gap period between the leading and trailing intervals. STK reports a satisfaction interval for the period of time when these conditions are met. The reported interval contains both leading and trailing visibility periods.
Broken: Satisfaction is met starting the moment within the leading interval when the maximum separation constraint is met until the last moment within the trailing interval when the maximum separation constraint is met. This is exclusive of any gap period between the leading and trailing intervals. Required conditions were met at all times during the reported interval. The reported interval contains both leading and trailing visibility periods.
Leading: Satisfaction is met at times between the moment within the leading interval when the maximum separation constraint is met until the last moment within the leading interval when the maximum separation constraint is met. Required conditions were met at all times during the reported interval. The reported interval contains only times within the leading visibility period.
Trailing: Satisfaction is met at times between the moment within the trailing interval when the maximum separation constraint is met until the last moment within the trailing interval when the maximum separation constraint is met. Required conditions were met at all times during the reported interval. The reported interval contains only times within the trailing visibility period.

The selected definition does not affect whether or not STK detects a satisfaction event, but it does affect the interval of time over which STK considers the FOM to be satisfied.

Access Separation is a logical Figure Of Merit, reporting values of either 1 or 0. The static value of Access Separation is 1 if the separation constraints are met at any time during the coverage interval. The dynamic value is equal to 1 if the constraints are met at the current time.

Here is an example of nonoverlapping leading/trailing access intervals with a 20-minute maximum separation constraint:

Here is an example of an overlapping leading/trailing access intervals with 20-minute maximum separation constraint:

Displaying access separation in a graphics window

Since the concept of satisfaction is implicit in the definition of this Figure Of Merit, you cannot set satisfaction options for this Figure Of Merit type.

The display of static and animation graphics depends on the values entered for the access measuring parameters above.

Static or Animation?	Grid points highlighted if they...
Static	satisfy the access separation criterion at some time during the coverage interval
Animation	currently satisfy the access separation criterion