Chains
Configure a chain object or computes access for a chain
Syntax
Chains <ObjectPath> {ChainOption} [<Parameters>]
Related commands
Description
The Chains command configures a chain.
Wildcards can be used in truncated paths that are passed into Connect.
{ChainOption} can be:
| {ChainOption} | <Parameters> | Description |
|---|---|---|
| Connections | <ConnectionOptions> | Sets the start object, end object, and connection options for the chain. |
| OptimalPath | <OptStrandOptions> | Sets the optimal strand options for the chain. |
| Compute | [ParallelCompute] | Computes access for the chain. Optionally, include the keyword ParallelCompute to compute the chain accesses in parallel, if available. |
| AutoRecompute | On | Automatically recompute access for the chain when a change occurs to any object in the chain.
This option applies only to changes made via the GUI. |
| Off | Do not automatically recompute access. | |
| SetComputeTime | {TimeOption} | Define the time period used to calculate accesses. See table below for valid {TimeOption} values. |
| ClearAccesses | N/A | Remove all chain accesses. |
| AccessIntervalsFile | {On | Off | "<Filename>"} | Specify a file into which Chain strand access intervals will be saved. If On is specified a Filename must already be defined or the command will Nack. |
| AdvComputeOptions | {AdvOptions} | Turn on or off and set parameters for light time delay and event detection and step size control in access calculations. See following table for details of {AdvOptions}. |
When modifying a Chain via Connect the Chain will not automatically recompute. The Chains Compute command must be used to recompute following any sequence of Connections, SetComputeTime or AdvComputeOptions commands.
Connections {ConnectionOptions}
{ConnectionOptions} can be:
| {ConnectionOption} | <Parameters> |
|---|---|
| SetStartInst | <TruncObjectPath> |
| SetEndInst | <TruncObjectPath> |
| SetStrandMaxDepth | <Value> |
| Add | {AddConnectionOptions} |
| Remove | {RemoveConnectionOptions} |
Connections Add {AddConnectionOptions}
{AddConnectionOptions} can be:
| {AddConnectionOption} | <Parameters> |
|---|---|
| From | <TruncObjectPath> |
| To | <TruncObjectPath> |
| MinNumHops | <Value> |
| MaxNumHops | <Value> |
If the new connection being added already exists in the set of connections, the new connection settings for min and max hops overwrites the old values in the set of connections.
Connections Remove {RemoveConnectionOptions}
{RemoveConnectionOptions} can be:
| {RemoveConnectionOption} | <Parameters> | Description |
|---|---|---|
| From | <TruncObjectPath> | All | Set the From object for the connection to be removed. If “All” is specified all Connections will be removed. Exactly one From object must be specified. |
| To | <TruncObjectPath> | Set the To object for the connection to be removed. If “All” is specified, all connections with the specified From Ob will be removed. This option must be specified at least once if the From option is not set to All. It can be specified multiple times to remove multiple connections for the same From object. |
SetComputeTime {TimeOption}
{TimeOption} can be:
| {TimeOption} | Description |
|---|---|
| UseObjects | The time period set for the objects in the chain is used to compute access. For facilities, places and targets, the time is the scenario time period. |
| UseScenario | The scenario time period is used to calculate accesses. |
| UserSpecified {TimeInterval} | Specify the Start and Stop times used for access calculations.
For valid {TimeInterval} values see Time Options. |
AdvComputeOptions {AdvOptions}
The following table describes the options for event detection and step size control. Any or all options can be included on the command line.
| {AdvOptions} | <Parameters> | Description |
|---|---|---|
| UseLightTimeDelay | {On | Off} | Turn on or off the use of light time delay in access calculations. |
| EventsBasedOnSamples | {On | Off} | Turn EventsBasedOnSamples On to determine access intervals simply based on the samples without doing any extra sub-sampling. |
| TimeConvergence | <Value> | Set the time tolerance used during event detection. Event times will be determined to within this specified tolerance. <Value> is entered in Connect Time units and must be between 1.0e-9 and 315576000.0 seconds.
EventsBasedOnSamples must be set to Off for this value to have any effect. |
| AbsValueConvergence | <Value> | Set the criterion used for convergence for values near 0. <Value> must be between 1e-30 and 1e30
EventsBasedOnSamples must be set to Off for this value to have any effect. |
| RelValueConvergence | <Value> | An event is said to be detected when a constraint value's relative difference compared to the previous sample is within this tolerance. <Value> must be between 0.0 and 1.0
EventsBasedOnSamples must be set to Off for this value to have any effect. |
| MaxStepSize | <Value> | Sets the maximum sampling step size used in access computations when computing the chain. <Value> is entered in Connect Time units and must be between 1.0e-5 and 315576000.0 seconds.
When this value is entered Step Size Control will be set to use a variable step to choose samples. |
| MinStepSize | <Value> | Sets the minimum sampling step size used in access computations when computing the chain. <Value> is entered in Connect Time units and must be between 1.0e-5 and 315576000.0 seconds.
When this value is entered Step Size Control will be set to use a variable step to choose samples. |
| FixedSampleStep | <Value> | Enter a step size value to control the step size used in Access sampling. <Value> is entered in Connect time units and must be between 1.0e-5 and 315576000.0 seconds.
When this value is entered Step Size Control will be set to use a fixed step to choose samples. |
| FixedStepTimeBound | <Value> | Enter a value control the alignment of samples with a UTC time grid. <Value> is entered in Connect time units and must be between 0.0 and 86400.0 seconds.
When this value is entered Step Size Control will be set to use a fixed step to choose samples. |
| MaxGoodLTDelay | <Value> | Set the allowable light time delay for the chain strands. <Value> is entered in Connect Time units and must be greater than 0.0001 seconds. |
| ConstellationConstraintMode | {Strand | Object} | Set the Constellation Constraints mode. |
OptimalStrand {OptStrandOptions}
{OptStrandOptions} can be:
| {OptStrandOptions} | <Parameters> | Description |
|---|---|---|
| Compute | {On | Off} | Enable or disable the computation of optimal strands. |
| Metric | {Distance | ProcessingDelay | ScalarCalculationName | ScalarCalculationFile } | Set the metric type used when computing optimal strands. |
| LinkCompareType | {Min | Max | Sum} | Set the method used to combine access pair metric values when computing the value of a strand. |
| StrandCompareType | {Min | Max} | Set the method used to compare strand metric values when determining the best strands. |
| ScalarCalculation | "access Calculation Scalar name" | Set the name of the Scalar Calculation used as the metric when the metric type is set to ScalarCalculationName. |
| ScalarCalculationFile | ".awb filepath" | Set the AWB file (.awb) for the Scalar Calculation used as the metric when the metric type is set to ScalarCalculationFile. |
| MaxSampleTimeStep | <Value> | Optimal strand sample times, specified in Connect time units. |
| IncludeAccessEdgeTimeInSamples | {On | Off} | Include start and stop times for all valid strand access intervals into the optimal strands sample times if enabled. |
| NumBestStrandsToStore | <Value> | Maximum number of optimal strands to store. |
Examples
To set the start instance for the chain ChainTest for the Place1 place:
Chains */Chain/ChainTest Connections SetStartInst Place/Place1
To set the end instance for the chain ChainTest for the Place2 place:
Chains */Chain/ChainTest Connections SetEndInst Place/Place2
To add a connection from the Place1 place to the Shuttle satellite to the chain ChainTest:
Chains */Chain/ChainTest Connections Add from Place/Place1 to Satellite/Shuttle
To add a connection from the Shuttle satellite to Place2 place to the chain ChainTest:
Chains */Chain/ChainTest Connections Add From Satellite/Shuttle to Place/Place2
To add a multi-hop connection for the Constellation1 constellation with two possible hops to the chain ChainTest:
Chains */Chain/ChainTest Connections Add From Constellation/Constellation1 To Constellation/Constellation1 MaxNumHops 2
To add a multi-hop connection for all satellites in SatelliteCollection1 with three possible hops to the chain ChainTest:
Chains */Chain/ChainTest Connections Add From SatelliteCollection/SatelliteCollection1/Subset/AllSatellites To SatelliteCollection/SatelliteCollection1/Subset/AllSatellites MaxNumHops 3
To remove the connection from the Shuttle satellite to the Place2 place for the chain ChainTest:
Chains */Chain/ChainTest Connections Remove From Satellite/Shuttle To Place/Place2
To remove all connections from Place1 place for the chain ChainTest:
Chains */Chain/ChainTest Connections Remove From Satellite/Shuttle To All
To remove all connection for the chain ChainTest:
Chains */Chain/ChainTest Connections Remove From All
To use Chain1's time period for access calculations:
Chains */Chain/Chain1 SetComputeTime UseObjects
To use the scenario time period for chain access calculations:
Chains */Chain/Chain1 SetComputeTime UseScenario
To consider only the specified portion of Chain1's time period for access calculations:
Chains */Chain/Chain1 SetComputeTime UserSpecified "14 Oct 2003 02:00:00.000" "14 Oct 2003 06:30:00.000"
To save strand accesses for RtChain chain to the file AccessChain1.int:
Chains */Chain/RtChain AccessIntervalsFile "c:/STKUser/AccessChain1.int"
To no longer save the RtChain chain strand accesses to a file:
Chains */Chain/RtChain AdvComputeOptions EventsBasedOnSamples Off TimeConvergence 0.55
To compute accesses for the chain:
Chains */Chain/RtChain Compute
To compute accesses for the Chain in parallel mode:
Chains */Chain/RtChain Compute ParallelCompute
To set the constellation constraints mode:
Chains */Chain/Chain1 ConstellationConstraintMode Object
To set the OptimalStrand metric calculation to use distance:
Chains */Chain/Chain1 OptimalStrand Metric Distance
To set the OptimalStrand sampling time:
Chains */Chain/Chain1 OptimalStrand MaxSampleTimeStep 60.0
To set the OptimalStrand number of strands to store:
Chains */Chain/Chain1 OptimalStrand NumBestStrandsToStore 3
To set the OptimalStrand strand comparison type:
Chains */Chain/Chain1 OptimalStrand StrandCompareType Min
To enable the computation of optimal strands:
Chains */Chain/Chain1 OptimalStrand Compute On
To set the OptimalStrand metric calculation to use processing delay:
Chains */Chain/Chain1 OptimalStrand Metric ProcessingDelay
To set the OptimalStrand scalar calculation metric name:
Chains */Chain/Chain1 OptimalStrand ScalarCalculationName “From-To-AER(Body).Cartesian.Magnitude”
To set the OptimalStrand metric calculation to use a built-in calculation scalar:
Chains */Chain/Chain1 OptimalStrand Metric ScalarCalculationName
To set the OptimalStrand scalar calculation metric file:
Chains */Chain/Chain1 OptimalStrand ScalarCalculationFile “C:\temp\myCalcScalar.awb”
To set the OptimalStrand metric calculation to use a calculation scalar file:
Chains */Chain/Chain1 OptimalStrand Metric ScalarCalculationFile
To set the OptimalStrand scalar calculation metric link comparison type:
Chains */Chain/Chain1 OptimalStrand LinkCompareType Sum
Return message
Group membership
This command belongs to the following group(s):
Version
12.8