Additional Radar Constraints

Custom Plugins for Radar Search/Track and SAR Constraints

The user plugin options on the Radar's Search/Track and Radar SAR Constraints pages extend the Search/Track and SAR computations. You can develop a data model in a MATLAB or VB script. STK interfaces with the script and updates the following at each time step of the scenario execution:

The script uses the STK-supplied data to compute a new parameter and return the value to STK.

For information on required inputs and outputs, see STK Radar Plugin Points.

For additional ways to extend the Search/Track and SAR analysis, see Additional Analyses Available.

To access additional STK scripting information, see Engine Plugin Scripts. For instructions on the setup and use of plugin points, see Plugin Scripts. To develop a custom script from a sample template, select the appropriate sample plugin script, in MATLAB or VBScript, from <STK install folder>\CodeSamples\Extend\PluginScripts.

STK radar object geometry data

Radar object geometry computations track light-speed signal propagation. The object's positions, velocities, accelerations, orientations, and rate of attitude changes all account for signal delays. The radar transmitter's geometry data corresponds to the times when the signal originated from the transmitter antenna. The target's geometry data is computed at the time when the signal arrives at the target. Similarly, the reflected signal from the target is received at the radar's receiver antenna and the signal arrival time is used to compute radar receiver geometry data.

The accounting for light speed propagation helps compute true object behavior. Due to the dynamics of the radar's parent object the signal transmission position, velocity and attitude can be different from the signal receive position, velocity and attitude. The impact may be more pronounced, especially for space applications. The light speed delay can range from a few milliseconds to the order of several minutes.

You can disable light-speed propagation delay computations by going to the Edit menu, selecting Preferences... > Access Defaults, and clearing the Use Light Time Delay check box. All signal propagation is then considered instantaneous; that is, the light speed is infinite. STK computes the radar, transmitter, target, and receiver-side geometry data exactly at the same time.

To obtain a detailed list of the radar target's object data, select the computed access from the Report & Graph Manager and bring up its associated "Radar Search/Track" data provider.

Vector Geometry Tool (VGT) data

The plugin script also has a connection to the VGT data interface. The script can refer to vectors, axes, points, angles, planes, and the coordinate systems. This provides access to additional objects in the scenario. For example, the angle between the radar receive-to-target vector and the receiver-to-sun vector could help detect Sun noise issues.

Similarly, you can define custom VGT data on top of the predefined VGT entities available in STK. The data regarding the custom defined VGT entities may be accessed by the plugin script just like the existing VGT items. For example, the radar can turn off if a jammer is too close.

Radar performance data

The following elements in the "Constraint Data" data provider are used to report plugin constraint performance data:

    For the access From object:

    • FromSARConstrPlugin
    • FromSrchTrkConstrPlugin

    For the access To object

    • ToSARConstrPlugin
    • ToSrchTrkConstrPlugin

You can configure a custom report style to add these elements to the Search/Track or the SAR data provider report styles. Once the elements are added to the report style, the values are reported like any other STK report parameter.

You can also add these elements to graph styles to graph the values.

For additional information on data providers and report styles for the SAR and Search/Track plugin constraints, see Radar Reports & Graphs.

Additional analyses available

You can also perform the following analyses with Radar Search/Track and SAR plugin constraints:

  • Figure of Merit (FOM) on Coverage. The Radar Search/Track and Radar SAR plugin constraints are also available as a figure of merit (FOM) value for FOM analysis.
  • Coverage Contour Graphics. Coverage graphics enable contouring of an FOM value on the 2D Graphics or 3D Graphics windows. The graphics can be static or dynamic, depending on the type of objects in the scenario.
  • Attitude Coverage Grid. Attitude coverage is a powerful tool for radar performance analysis. A figure-of-merit contour plot on the attitude sphere shows the FOM high and low points for optimizing the radar operation. For example, a C/(N+I) contour plot on the attitude sphere will clearly show the worst jamming directions. The radar operator may be able to steer antenna nulls to minimize the impact of jamming.