STK Communications and STK Radar Plugin Points

STK Communications provides the following plugin points:

STK Radar provides the following plugin points:

Transmitter Model

Input Arguments

The Transmitter Model plugin point has the following available inputs:

Name Representation Units Definition
DateUTC String --- The current date and time.
CbName String --- The scenario central body.
EpochSec Double sec The scenario simulation epoch time.
XmtrPosCBF Double:3 m The transmitter position in Central Body Fixed coordinates. A vector of doubles, of length 3, corresponding to the X, Y and Z values.
XmtrAttitude Double:4 --- The attitude quaternion of the transmitter. A vector of doubles, of length 4.
RcvrPosCBF Double:3 m The position of the receiver to which the transmitter is linking in the current time step, in Central Body Fixed coordinates. A vector of doubles, of length 3, corresponding to the X, Y and Z values.
RcvrAttitude Double:4 --- The attitude quaternion of the receiver to which the transmitter is linking in the current time step. A vector of doubles, of length 4.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
Frequency Double Hz The frequency of the transmitter RF carrier.
Power Double dBW The final output power.
Gain Double dBi The gain of the radiating elements of the antenna.
DataRate Double bits/sec The information bit rate.
Bandwidth Double Hz The bandwidth of the RF spectrum.
Modulation String --- The type of modulation used by the transmitter. This must be one of the STK registered modulation types. However, you can add your own modulation types, and STK will register them.
PostTransmitLoss Double dB A collection of post-transmit losses, e.g. antenna dish coupling or random loss.
PolType Integer --- The type of polarization.
PolRefAxis Integer --- The polarization reference axis used to align transmitter polarization to receiver polarization, with 0, 1 and 2 representing the X, Y and Z axes, respectively.
PolTiltAngle Double deg The polarization tilt angle measured from the reference axis.
PolAxialRatio Real --- The polarization axial ratio.
UseCDMASpreadGain Boolean --- A flag (0 or 1) that specifies whether or not to use the bandwidth spreading gain.
CDMAGain Double dB The CDMA coding processing gain.
UsePSD Boolean --- A flag (0 or 1) that specifies whether or not STK should use PSD. If true, the shape of the PSD is created based on the Modulation output parameter; otherwise, a flat spectrum is utilized.

PolType Values and Polarization Types

The correlation between the integer values of the PolType element and the different polarization types and their required parameters is given in the following table:

Value Polarization Type Required Parameter(s)
0 None None
1 Linear Reference Axis
2 Right Hand Circular None
3 Left Hand Circular None
4 Vertical Reference Axis, Tilt Angle
5 Horizontal Reference Axis, Tilt Angle
6 Elliptical Reference Axis, Tilt Angle, Axial Ratio

Receiver Model

Input Arguments

The Receiver Model plugin point has the following available inputs:

Name Representation Units Definition
DateUTC String --- The current date and time.
CbName String --- The scenario central body.
EpochSec Double sec The scenario simulation epoch time.
XmtrPosCBF Double:3 m The position of the transmitter to which the receiver is linking in the current type step, in Central Body Fixed coordinates. A vector of doubles, of length 3, corresponding to the X, Y and Z values.
XmtrAttitude Double:4 --- The attitude quaternion of the transmitter to which the receiver is linking in the current type step. A vector of doubles, of length 4.
RcvrPosCBF Double:3 m The receiver position in Central Body Fixed coordinates. A vector of doubles, of length 3, corresponding to the X, Y and Z values.
RcvrAttitude Double:4 --- The attitude quaternion of the receiver. A vector of doubles, of length 4.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
Frequency Double Hz The tuned receiver frequency of the RF carrier.
Bandwidth Double Hz The bandwidth of the receiver front end.
Gain Double dBi The gain of the radiating elements of the antenna.
PreReceiveLoss Double dB A collection of pre-receive losses.
PreDemodLoss Double dB A collection of pre-demodulation losses.
UseRainModel Boolean --- A flag (0 or 1) that specifies whether a rain model is to be used.
RainOutagePercent Double % The outage value ( 0 through 100) that can be tolerated by the link.
PolType Integer --- The type of polarization.
PolRefAxis Integer --- The polarization reference axis used to align transmitter polarization to receiver polarization, with 0, 1 and 2 representing the X, Y and Z axes, respectively.
PolTiltAngle Double deg The polarization tilt angle measured from the reference axis.
PolAxialRatio Real --- The polarization axial ratio.
CrossPolLeakage Double dB The performance of the user's system, ranging from -9999.9 dB to 0.0 dB, where -9999.9 dB represents ideal conditions (no leakage).
CalcReceiverNoiseTemp Boolean --- A flag (0 or 1). Set to 0 to use the ConstantNoiseTemp value (below) or to 1 to have STK compute noise temperature.
ConstantNoiseTemp Double K If CalcReceiverNoiseTemp is set to 0, specify the noise temperature.
ReceiverNoiseFigure Double dB The receiver pre-amplifier noise figure.
CableLoss Double dB The cable loss value.
CableNoiseTemp Double K The temperature of the cable.
AntennaNoiseTemp Double K The receiver antenna noise temperature.

Custom Antenna Gain

Input Arguments

The Custom Antenna Gain plugin point has the following available inputs:

Name Representation Units Definition
EpochSec Double sec The scenario simulation epoch time.
DateUTC String --- The current date and time.
CbName String --- The scenario central body.
Frequency Double Hz The current frequency at which antenna gain is desired.
AntennaPosLLA Double:3 rad,
rad,
m
A vector of doubles, of length 3, representing latitude, longitude and altitude of the antenna above the surface of the Earth.
AntennaCoordSystem Boolean -- A flag (0 or 1). Set to 0 for Polar antenna coordinate system and 1 for Rectangular antenna coordinate system.
AzimuthAngle Double rad The azimuth angle measured from the antenna boresight in the antenna coordinate system used by STK. In combination with ElevationAngle, represents the direction of the comm. link where the gain value is required.
ElevationAngle Double rad The elevation angle measured from the antenna boresight in the antenna coordinate system used by STK. In combination with AzimuthAngle, represents the direction of the comm. link where the gain value is required.

The above angles are measured from the boresight of the antenna and are in the antenna Polar Coordinate System used by STK.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
AntennaCoordSystem Boolean -- Values are 0 for Polar antenna coordinate system and 1 for Rectangular antenna coordinate system.
AntennaGain Double dBi The antenna gain value in the direction given by the azimuth and elevation angles of the antenna boresight.
AntennaMaxGain Double dBi The maximum gain of the antenna beam. This value may be at the boresight.
Beamwidth Double rad The 3dB beamwidth of the antenna gain pattern.
IntegratedGain Double --- The antenna integrated gain over a noise source. This value is currently estimated by STK using internal numerical methods. Future versions will use a value supplied by the scripts.
DynamicGain Boolean --- Displays a new 3D volume and 2D contour at each time step. Setting DynamicGain to 1 will incur a greater performance penalty due to increased graphics computations. Valid values are 1 to enable DynamicGain and 0 to disable it.

Absorption Loss Model

Input Arguments

The Absorption Loss Model plugin point has the following available inputs:

Name Representation Units Definition
EpochSec Double sec The scenario simulation epoch time.
DateUTC String --- The current date and time.
CbName String --- The scenario central body.
Frequency Double Hz The Comm link frequency at the current time instant, at which the link budget analysis is being carried out. This would also be the Doppler shifted frequency at the receiver, which is using the frequency to compute propagation losses and noise temperatures to compute its g/T.
XmtrPosCBF Double:3 m The transmitter position in Central Body Fixed coordinates. A vector of doubles, of length 3, corresponding to the X, Y and Z values.
RcvrPosCBF Double:3 m The receiver position in Central Body Fixed coordinates. A vector of doubles, of length 3, corresponding to the X, Y and Z values.
XmtrPath String --- A string representing the complete scenario path of the current transmitter object.
RcvrPath String --- A string representing the complete scenario path of the current receiver object.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
AbsorpLoss Double dB The propagation loss term.
NoiseTemp Double K The noise temperature associated with the propagation loss, used by STK to compute the antenna noise temperature and the receiver g/T values.

Phased Array Direction Provider

This script computes the direction(s) for the beam (or nulls) at each time step. The following fields can be set on the Direction Provider:

Parameter Description
Filename Name of the script file. File type can be Perl, Visual Basic, or MATLAB.
Members

The STK Objects for which information is passed to the script. Members can be any STK Object that has a position. For example, members can be "platforms" such as Aircraft, Satellites, Ground Vehicles, etc. or can be RF "payloads" such as Transmitters, Receivers, and Radars. If the member is an RF "payload" then the script receives the frequency of the object; otherwise, the frequency field is set to -1.

Only objects that do not share the same root ancestry as the phased array's root ancestor are allowed.

Input Arguments

The Direction Provider plugin script will be provided with the following inputs at each time step:

Name Representation Description
ObjectPath char [256] Fully qualified name of the object utilizing this direction provider.
EpochSec double Current simulation epoch seconds.
PosLLA double [3] Position (in LLA) of the object utilizing this direction provider. Latitude and longitude are in degrees and altitude is in meters.
PosCBF double [3] Position (in CBF) of the object utilizing this direction provider. X, Y, and Z are in meters.
MemberPositionFormat double [3] Indicates the coordinate system for the MemberPositions array. Current choices are 1 for relative positions in spherical Az/El/Range (default) or 0 for Cartesian. For Az/El/Range, the azimuth and elevation are in degrees and range is in meters. For Cartesian, X,Y, and Z are in meters.
NumberOfMembers int Number of members in view at this time step. Defines the size of member input fields to follow. Maximum number of members is currently set to 100.
MemberPositions double [3][NumberOfMembers] The positions of each member in view for the current EpochSec. Positions are in the format as specified by MemberPositionFormat
MemberFrequencies double[NumberOfMembers] If the object can emit or sense (Transmitter, Receiver, or Radar), the array element is set to the object's frequency. Otherwise, this array element is set to -1.
MemberPwrs double[NumberOfMembers] If the object can emit (Transmitter or Radar), the array element is set to the object's EIRP. Otherwise, this array element is set to -1e300.
MemberIds int[NumberOfMembers] An integer number that uniquely identifies each member instance, where each ID corresponds to its position in the Direction Provider Members field. The first member has an ID of 0.
MemberCategory int An integer that identifies the type of the object (Aircraft, Facility, GroundVehicle, etc). See Object Type for the different object type indicators.

Output Arguments

STK expects the script output data to be passed back from the script to STK. The outputs of this script are passed as inputs to the Beamformer. See Input Arguments for a description of the inputs to the script. See Output Arguments for a description of the outputs to the script.

The following outputs are expected from the script by STK:

Name Representation Description
IsDynamic

bool

Indicates the script is time dynamic, which causes STK to call the script at each time step.
NumDirections int Number of directions being returned. Currently the Beam script only supports one direction being returned. Currently the Null script can support up to a maximum of 100.
Azimuths double[NumDirections] Azimuths of each steering direction in radians (-pi to pi). See Antenna Coordinate System for more information.
Elevations double[NumDirections] Elevations of each steering direction in radians (-pi/2 to pi/2). See Antenna Coordinate System for more information.

Object Types

Indicator Object Type
1 Aircraft
8 Facility
9 Ground Vehicle
10 Launch Vehicle
13 Missile
15 Planet
16 Radar
17 Receiver
18 Satellite
20 Sensor
21 Ship
22 Star
23 Target
24 Transmitter
30 Submarine

Phased Array Beamformer

This script computes a weight for each element within the Element Configuration at each time step.

The following fields can be set in the Beamformer script.

Parameter Description
Filename Name of the script file. File type can be Perl, Visual Basic, or MATLAB.

Some of the input data includes some of the output data from the Direction Provider. STK expects the script output data to be passed back from the script to STK. See the Input Arguments for script input information. See the Output Arguments for script output information.

Input Arguments

Name Representation Description
EpochSec double Current simulation epoch seconds.
NumberOfElements int Number of antenna elements in the array.
NumberOfBeamDirections int Number of beam directions to follow. Currently, maximum of 1.
BeamDirections double[1][2] Array of Az/El values (rad/rad) representing the direction to steer beam(s) toward.
NumberOfNullDirections int Number of null directions. Maximum of 100.
NullDirections double[100][2] Array of Az/El values (rad/rad) representing the direction to steer null(s) toward.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Description
IsDynamic bool Indicates the script is time dynamic, which causes STK to call the script at each time step.
Weights double[2][NumberOfElements] Complex weight values for each antenna element. Format is a linear array of real and imaginary values (interleaved).

Custom Loss Model

The Custom Loss Model has the same format as the Absorption Loss model plugin script. To develop a custom script from a sample template, select an absorption loss model plugin script, in MATLAB, Perl, or VBScript from \CodeSamples\Extend\PluginScripts.

Rain Loss Model

Input Arguments

The Rain Loss Model plugin point has the following available inputs:

Name Representation Units Definition
EpochSec Double sec The scenario simulation epoch time.
DateUTC String --- The current date and time.
CbName String --- The scenario central body.
Frequency Double Hz The Comm link frequency at the current time instant, at which the link budget analysis is being carried out. This would also be the Doppler shifted frequency at the receiver, which is using the frequency to compute propagation losses and noise temperatures to compute its g/T.
ElevAngle Double rad The communication link path elevation angle from the lower terminal to the higher altitude level terminal.
OutagePercentage Double --- The percent of the time that the communication link can tolerate outage.
RcvrPosLLA Double:3 rad,
rad,
m
A vector of doubles, of length 3, representing latitude, longitude and altitude of the receiver above the surface of the Earth.
XmtrPosLLA Double:3 rad,
rad,
m
A vector of doubles, of length 3, representing latitude, longitude and altitude of the transmitter above the surface of the Earth.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
RainLoss Double dB The loss value due to rain.
RainNoiseTemp Double K The noise temperature associated with the rain loss.

Antenna Multibeam Selection Strategy

Input Arguments

The Antenna Multibeam Selection Strategy plugin point has the following available inputs:

Name Representation Units Definition
EpochSec Double sec The scenario simulation epoch time.
DateUTC String --- The current date and time.
CbName String --- The scenario central body.
AntennaPosLLA Double:3 rad,
rad,
m
A vector of doubles, of length 3, representing latitude, longitude and altitude of the antenna above the surface of the Earth.
BeamIDsArray Char --- A two-dimensional array of characters. The array has a fixed width (number of columns) of 64, and the length of the array (number of rows) is equal to the number of beams available in the multibeam antenna. The array is parsed by the script to obtain the beam IDs. Each row of the character array contains the BeamID of one beam.
NumberOfBeams Integer --- The total number of beams available in the multibeam antenna at each time instant. This also represents the length of arrays that contain the beam characteristic information, e.g. ID, frequency, power, etc.
Frequency Double Hz An array of real values that contains the beam frequency information for each beam. The length of the beam array is equal to the NumberOfBeams element.
Power Double dBW For multibeam antennas attached to transmitters. These will have an additional array containing the power value for each beam. The receiver antenna beam power array contains all zero values.
IsActive Integer --- An array of integers indicating whether each beam is active (1) or inactive (0) in the multibeam model.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
BeamNumber Integer --- The serial number of the beam, in the range 1-n, where n = NumberOfBeams, to be used for link computations.

CommSystem Link Selection Strategy

Input Arguments

The CommSystem Link Selection Strategy plugin point has the following available inputs:

Name Representation Units Definition
DateUTC String --- The current date and time.
EpochSec Double sec The scenario simulation epoch time.
CbName String --- The scenario central body.
CommSysPath String --- The full path and name of the CommSystem in the scenario that defines the interference environment and contains the link selection strategy.
FromIndex Integer --- The index number of the transmitter from the array of transmitters that is currently being used as the link object. Starts at 0.
NumberOfFromObjects Integer --- The total number of transmitters in the transmitter array being passed to the script.
FromObjectsIDArray Char --- The IDs of the transmitters in the array containing information about all the transmitters.
FromObjectIsStatic Boolean --- Flag indicating whether the transmitter object is static, i.e. fixed on the ground in position and attitude.
FromObjectPosCBFArray Double:3 m The positions of the transmitters in the CBF Cartesian coordinate frame. Each element of the array gives position for one transmitter.
FromObjectPosLLAArray Double:3 rad,
rad,
m
The positions of the transmitters in latitude, longitude and altitude. Each element of the array gives position for one transmitter.
FromToRelPosArray Double:3 m The relative positions of the transmitters with respect to the current receiver object in the Cartesian coordinate frame.
FromObjectAttitudeArray Double:4 --- An array of attitude quaternions (vectors of length 4) of the transmitters.
ToIndex Integer --- The index number of the receiver from the array of receivers that is currently being used as the link object. Starts at 0.
NumberOfToObjects Integer --- The total number of receivers in the receiver array being passed to the script.
ToObjectsIDArray Char --- The IDs of the receivers in the array containing information about all the receivers.
ToObjectIsStatic Boolean --- Flag indicating whether the receiver object is static, i.e. fixed on the ground in position and attitude.
ToObjectPosCBFArray Double:3 m The positions of the receivers in the CBF Cartesian coordinate frame. Each element of the array gives position for one receiver.
ToObjectPosLLAArray Double:3 rad,
rad,
m
The positions of the receivers in latitude, longitude and altitude. Each element of the array gives position for one receiver.
ToFromRelPosArray Double:3 m The relative positions of the receivers with respect to the current transmitter object in the Cartesian coordinate frame.
ToObjectAttitudeArray Double:4 --- An array of attitude quaternions (vectors of length 4) of the receivers.

Each transmitter-receiver link pair is identified to the script using index values representing positions in the arrays of transmitters and receivers. Information about the attributes of all transmitters and receivers is passed to the script in the form of arrays. The script is called for each transmitter-receiver link pair available at each time instant. The expected output is a “cost” for the link. After the script is called for all available links for a given time instance, STK will order the costs in ascending order and select the first entry as the selected link.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
SatSelMeritValue Double --- The relative merit value assigned to the link being analyzed. The scale is open-ended.

Satellite Selection Merit Value

Each transmitter-receiver link pair is identified to the script using index values representing positions in the arrays of transmitters and receivers. Information about the attributes of all transmitters and receivers is passed to the script in the form of arrays. The script is called for each transmitter-receiver link pair available at each time instant. The expected output is the rank order of these links on a relative scale. STK then uses the links beginning with the highest ranking.

Modulator

The Modulator has been broken down into two different script output interfaces, a Custom PSD Script, and an Ideal PSD Script. The first script output interface, Custom PSD Script, allows you to dynamically specify the Power Spectral Density as a set of magnitude values over a frequency range. The other interface, Ideal PSD Script, allows you to dynamically select a modulation and encoding, letting STK compute a theoretical PSD rather than you having to specify the points for a theoretical PSD. Both types of scripts have the same input interface. The available inputs for both followed by the outputs for each of the script output interfaces are provided below.

Input Arguments

The Modulator Script plugin point has the following available inputs:

Name Representation Units Definition
DateUTC String --- The current date and time.
CbName String --- The scenario central body.
ObjectPath String --- Path name of the object.
ObjectPosLLA Double-3 rad, rad, m Object position in Lat/Lon/Altitude.
EpochSec Double sec Current simulation time value since epoch.
RFCarrierFreq Double Hz RF carrier frequency.
DataRate Double bits/sec Data rate of the transmitter.

Output Arguments – Custom PSD Script Modulator

The following outputs are expected from the script by STK:

Name Representation Units Definition
IsDynamic Integer ---

Indicates if script is time-dynamic (0,1). If 0 (false), the script is only called once for all times (at EpochSec = 0) and the returned data is utilized for each time step. If 1 (true), the script is called for each time step.

ModulationName String --- Name of the modulation, used by the receiver for proper demodulation.
SpectrumLimitLow Double Hz Lower band limit of output spectrum relative to RF carrier frequency (-100e9 to 0).
SpectrumLimitHi Double Hz Upper band limit of output spectrum relative to RF carrier frequency (0 to 100e9).
UsePSD Integer --- Use signal PSD indicator. If 0 (false), the NumPSDPoints returned is set to 0. (0 to 1)
PSDData Double --- PSD data.
FreqStepSize Double Hz Frequency step size of the PSD data.

Output Arguments - Ideal PSD Script Modulator

The following outputs are expected from the script by STK:

Name Representation Units Definition
IsDynamic Integer ---

Indicates if script is time-dynamic (0,1). If 0 (false), the script is only called once for all times (at EpochSec = 0) and the returned data is utilized for each time step. If 1 (true), the script is called for each time step.

ModulationName String --- Name of the modulation, used by the receiver for proper demodulation.
ModulationEfficiency Double Hz/(bits/sec)

Specifies the spectral efficiency of the user’s modulation prior to any encoding.

This return value is ignored if UsePSD value is set to 1.

CodeRate Double ---

The rate of the encoding scheme. For example, an encoding scheme which takes in 1 information bit and encodes it into 2 encoded bits has a code rate of 0.5.

PSDShape String ---

When UsePSD value is set to 1, this will define the shape of the PSD.

If the value does not match one of the modulation types registered within STK, STK will produce a flat PSD spectra across the specified low/hi spectrum values.

SpectrumLimitLow Double Hz Lower band limit of output spectrum relative to RF carrier frequency (-100e9 to 0).
SpectrumLimitHi Double Hz Upper band limit of output spectrum relative to RF carrier frequency (0 to 100e9).
UsePSD Integer --- Use signal PSD indicator. If 0 (false), the NumPSDPoints returned is set to 0. (0 to 1)
ChipsPerBit Integer --- Number of chips per bit. This return value is ignored if UsePSD value is set to 1.

 

Demodulator

Input Arguments

The Demodulator Script plugin point has the following available inputs:

Name Representation Units Definition
DateUTC String --- The current date and time.
CbName String --- The scenario central body.
ObjectPath String --- Path name of the object.
ObjectPosLLA Double-3 rad, rad, m Object position in Lat/Lon/Altitude.
FunctionName String ---

The FunctionName tells the plugin script whether EbNo or BER needs to be computed.

<String> is {ComputeBER | ComputeEbNo}.

Demodulation process uses these functions to compute BER for a given value of EbNo. When the FunctionName is ComputeBER, SignalEbNo value is set and a corresponding BER value is expected in OutBER.

Link Margin analysis also uses these functions to compute EbNo (as a link margin value) for a given BER. When the FunctionName is ComputeEbNo, SignalBER is set to a value and a corresponding EbNo value is expected in OutEbNo.

EpochSec Double sec Current simulation time value since epoch.
RFFreq Double Hz RF Frequency of the incoming signal.
DataRate Double bits/sec Data rate of the incoming signal.
SpectrumLimitLo Double Hz The lower bandwidth limit for which the incoming signal is defined over. The bandwidth limit is relative to RFFreq value and will be a negative value. The limit is considered to be a sharp cutoff point and the spectrum is zero beyond the limit.
SpectrumLimitHi Double Hz The upper bandwidth limit for which the incoming signal is defined over. The bandwidth limit is relative to RFFreq value and will be a positive value. The limit is considered to be a sharp cutoff point and the spectrum is zero beyond the limit.
SignalModulationName String --- The name of the modulation of the incoming modulated signal.
SignalBER Double --- Used for Link Margin Analysis. When FunctionName is set to {ComputeEbNo} this will be valued with the BER value for which to compute an Eb/No value. The computed Eb/No value should be returned in the script’s output parameters.
SignalEbNo Double dB The computed Eb/No value for which the demodulator should compute a BER value. The computed BER value should be returned in the script’s output parameters.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
IsDynamic Integer ---

Indicates if script is time-dynamic (0,1). If 0 (false), the script is only called once for all times (at EpochSec = 0) and the returned data is utilized for each time step. If 1 (true), the script is called for each time step.

OutBER Double --- BER value when Eb/No is input. See SignalEbNo.
OutEbNo Double dB Eb/No value when BER is input. See SignalBER.

Filter

Input Arguments

The Filter Model plugin point has the following available inputs:

Name Representation Units Definition
DateUTC String --- The current date and time.
CbName String --- The scenario central body.
ObjectPath String --- Scenario path of the object.
ObjectPosLLA Double-3 rad, rad, m Object position in Lat/Lon/Altitude.
EpochSec Double sec Current simulation time value since epoch.
CenterFreq Double Hz Filter’s center frequency.
FreqStepSize Double Hz Filter’s frequency step size.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
IsDynamic Integer --- Indicates if script is time-dynamic (0,1). If 0 (false), the script is only called once for all times (at EpochSec = 0) and the returned data is utilized for each time step. If 1 (true), the script is called for each time step.
LowerBandlimit Double Hz The lower bandwidth limit for which the filter is defined over. The bandwidth limit is relative to the CenterFreq input value and must be a negative value. The limit is considered to be a sharp cutoff point and the filter has complete attenuation beyond the limit.
UpperBandlimit Double Hz The upper bandwidth limit for which the filter is defined over. The bandwidth limit is relative to the CenterFreq input value and must be a positive value. The limit is considered to be a sharp cutoff point and the filter has complete attenuation beyond the limit.
NumPoints Integer --- Number of filter samples being returned in Attenuation.
Attenuation Double dB Array of attenuation values.

Comm Constraint

The following contains information on a plugin that applies Comm link budget criteria to determine whether access exists.

Access Constraint plugin points are also available for Comm objects.

Input Arguments

The Comm Constraint plugin point has the following available inputs:

Name Representation Units Definition
DateUTC String --- The current date and time.
EpochSec Double sec The scenario simulation epoch time.
CbName String --- The scenario central body.
ReceiverPath String --- A string representing the complete scenario path of the current receiver object.
TransmitterPath String --- A string representing the complete scenario path of the current transmitter object.
RcvrPosCBF Double:3 m The receiver position, in Central Body Fixed coordinates. A vector of doubles, of length 3, corresponding to the X, Y and Z values.
RcvrAttitude Double:4 --- The attitude quaternion of the receiver. A vector of doubles, of length 4.
XmtrPosCBF Double:3 m The transmitter position in Central Body Fixed coordinates. A vector of doubles, of length 3, corresponding to the X, Y and Z values.
XmtrAttitude Double:4 --- The attitude quaternion of the transmitter. A vector of doubles, of length 4.
ReceivedFrequency Double Hz The frequency of the signal as seen by the receiver. This value includes any Doppler shift.
DataRate Double bits/sec The information bit rate.
Bandwidth Double Hz The bandwidth of the RF spectrum.
CDMAGainValue Double dB The CDMA coding gain.
ReceiverGain Double dB The antenna gain in the direction of the transmitter.
PolEfficiency Double --- Polarization efficiency is the polarization mismatch loss due to the misalignment of the reference axes of the transmitter and the receiver. It is expressed on a scale of 0 - 1.
PolRelativeAngle Double rad The Polarization Relative angle is the relative angle between the transmitter's polarization reference axis and the receiver's polarization reference axis. The angles are computed after taking into consideration the attitudes of the all of the antenna's parent objects, the orientations of the sensors (if any) and the orientation of the antennas with respect to the transmitter or receiver's body axis.
RIP Double dB(W/m^2) The Received Isotropic Power at the receiver antenna.
FluxDensity Double dB(W/m^2 Hz) The Power flux density at the receiver antenna.
GOverT Double dB/K The receiver gain over the equivalent noise temperature.
CarrierPower Double dBW The Carrier power at the receiver input. This is the power received at the receiver LNA input. It takes into consideration pre-receiver losses, antenna gain, cable losses, etc.
BandwidthOverlap Double --- This is a fraction from 0 to 1 representing the amount of overlap between the transmitted signal and the receiver bandwidths. The amount of power received by the receiver is equal to the transmitted EIRP multiplied by the bandwidth overlap and taking into account any propagation losses.
Cno Double dB The Carrier-to-Noise density at the receiver input.
CNR Double dB The Carrier-to-Noise ratio at the receiver input.
EbNo Double dB The Signal-to-Noise ratio at the receiver.
BER Double --- The Bit Error Rate.

Output Arguments

The following outputs are expected from the script by STK:

Name Representation Units Definition
PluginConstraintValue Double dB The value is compared with the Min and Max values entered on the Communications constraint page to determine whether access exists.

Search/Track Constraint

The Search/Track Constraint plugin extends the Search/Track mode computations. STK interfaces with the plugin script and provides updated object geometry, VGT data and radar performance data 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.

Input Arguments

The following table gives representation (data type) and, where applicable, unit information on each of the input arguments for the Search/Track Constraint plugin point.

Name Representation Units Definition
DateUTC String --- The current date and time.
EpochSec Double sec The scenario simulation epoch time.
CbName String --- The scenario central body.
RadarPath String --- Scenario path for radar object.
TargetPath String --- Scenario path for target object.
RadarTransmitPosCBF Double-3 m Radar transmitter position in CBF (accounts for Light Time Delay).
RadarTransmitAttitudeQuat Double-4 --- Radar transmitter attitude.
RadarReceivePosCBF Double-3 m Radar receiver position in CBF (accounts for Light Time Delay).
RadarReceiveAttitudeQuat Double-4 --- Radar receiver attitude.
TargetPosCBF Double-3 m Target position in CBF (accounts for Light Time Delay).
TargetAttitudeQuat Double-4 --- Target attitude.
RadarTransmitterToTargetVecBF Double-3 m Radar transmitter to target vector in radar body frame.
RadarReceiverToTargetVecBF Double-3 m Radar receiver to target vector in radar body frame.
TargetToRadarReceiverVecBF Double-3 m Target to radar receiver vector in radar body frame.
RadarTransmitterToTargetRange Double m Range from radar transmitter to target.
RadarReceiverToTargetRange Double m Range from target to radar receiver.
AngleRate Double radian/sec Angle rate between target to radar receiver LOS vector and the target to radar receiver velocity vector.
ConeAngle Double rad Angle between radar receiver position vector and velocity vector.
TransmitPropagationTime Double sec Signal propagation time from transmitter to target.
ReceivePropagationTime Double sec Signal propagation time from target to receiver.
TransmitRangeRate Double meters/sec Transmitter side range rate to target.
ReceiveRangeRate Double meters/sec Receiver side range rate to target.
RadarSpeed Double meters/sec Magnitude of radar receiver CBF velocity.
RefractedElevationAngle Double rad Refracted elevation angle if refraction is on.
RadarTransmitFrequency Double Hz Radar transmitter frequency.
DopplerShiftedFrequencyAtTarget Double Hz Doppler shifted frequency at target.
DopplerShiftedFrequencyAtRadarReceiver Double Hz Doppler shifter frequency at radar receiver.
ST_SinglePulseSNR Double dB Single pulse signal-to-noise ratio for the search/track radar. For a CW radar, the single pulse SNR is the SNR resulting from an effective pulse width of 1 second.
ST_IntegratedSNR Double dB Integrated signal-to-noise ratio.
ST_NumIntegratedPulses Double --- Number of signal pulses integrated.
ST_IntegrationTime Double sec Pulse integration time.
ST_DwellTime Double sec The sum of the integration time and RF propagation delays.
ST_TargetRange Double m Ambiguous target range.
ST_TargetVelocity Double meters/sec Ambiguous target velocity.
ST_TargetMLCVelocity Double meters/sec Measured MLC velocity.
ST_TargetInClearDopplerZone Integer --- Target in clear doppler zone.
ST_TargetInMLCFilter Integer --- MLC suppressing target flag.
ST_TargetInSLCFilter Integer --- SLC suppressing target flag.
ST_UnambigRangeFlag Boolean --- The value is set at 0 or 1.
ST_UnambigVelFlag Boolean --- The value is set at 0 or 1.
ST_NoiseBandwidth Double Hz Radar receiver noise bandwidth.
ST_NoisePower Double dBW Radar receiver noise power.
ST_SinglePulseProbDetection Double --- Single pulse probability of detection. The value ranges between 0 and 1.
ST_IntegratedProbDetection Double --- The value ranges between 0 and 1.
ST_NonCFARDetectThreshold Double dB Non-CFAR detection threshold.
ST_CFARThresholdMultiplier Double --- Non-CFAR detection threshold multiplier.
ST_SinglePulseSNRUnderJamming Double dB S/(N+J) for a single pulse.
ST_IntegratedSNRUnderJamming Double dB S/(N+J) integrated over total number of pulses.
ST_SinglePulseProbDetectionUnderJamming Double --- The value ranges between 0 and 1. Single pulse probability of detection under jamming.
ST_IntegratedProbDetectionUnderJamming Double --- The value ranges between 0 and 1. Integrated pulse probability of detection under jamming.
ST_IntegrationTimeUnderJamming Double sec Integrated time under jamming.
ST_NumIntegratedPulsesUnderJamming Double --- Total number of pulses integrated under jamming.
ST_DwellTimeUnderJamming Double sec Dwell time under jamming.
ST_JOverS Double dB Single pulse J/S.
ST_IntegratedJOverS Double dB Integrated J/S.
ST_JammingPower Double dBW Total jamming power.

Output Arguments

The following table gives representation (data type) and, where applicable, unit information on each of the output arguments for the Search/Track Constraint plugin point.

Name Representation Units Definition
Constraint Double --- A value returned by the script to STK Access at this time instant. STK applies the Min and Max constraint criteria and the Exclude Interval flag (if checked) to this value to determine access availability.

SAR Constraint

The SAR Constraint plugin extends the SAR mode computations. STK interfaces with the plugin script and provides updated object geometry, VGT data and radar performance data 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.

Input Arguments

The following table gives representation (data type) and, where applicable, unit information on each of the input arguments for the SAR Constraint plugin point.

Name Representation Units Definition
DateUTC String --- The current date and time.
EpochSec Double sec The scenario simulation epoch time.
CbName String --- The scenario central body.
RadarPath String --- Scenario path for radar object.
TargetPath String --- Scenario path for target object.
RadarTransmitPosCBF Double-3 m Radar transmitter position in CBF.
RadarTransmitAttitudeQuat Double-4 --- Radar transmitter attitude.
RadarReceivePosCBF Double-3 m Radar receiver position in CBF (accounts for Light Time Delay).
RadarReceiveAttitudeQuat Double-4 --- Radar receiver attitude.
TargetPosCBF Double-3 m Target position in CBF.
TargetAttitudeQuat Double-4 --- Target attitude.
RadarTransmitterToTargetVecBF Double-3 m Radar transmitter to target vector in radar body frame.
RadarReceiverToTargetVecBF Double-3 m Radar receiver to target vector in radar body frame.
TargetToRadarReceiverVecBF Double-3 m Target to radar receiver vector in radar body frame.
RadarTransmitterToTargetRange Double m Range from radar transmitter to target.
RadarReceiverToTargetRange Double m Range from target to radar receiver.
AngleRate Double rad/sec Angle rate between target to radar receiver LOS vector and the target to radar receiver velocity vector.
ConeAngle Double rad Angle between radar receiver position vector and velocity vector.
TransmitPropagationTime Double sec Signal propagation time from transmitter to target.
ReceivePropagationTime Double sec Signal propagation time from target to receiver.
TransmitRangeRate Double m/sec Transmitter side range rate to target.
ReceiveRangeRate Double m/sec Receiver side range rate to target.
RadarSpeed Double m/sec Magnitude of radar receiver CBF velocity.
RefractedElevationAngle Double rad Refracted elevation angle if refraction is on.
RadarTransmitFrequency Double Hz Radar transmitter frequency.
DopplerShiftedFrequencyAtTarget Double Hz Doppler shifted frequency at target.
DopplerShiftedFrequencyAtRadarReceiver Double Hz Doppler shifter frequency at radar receiver.
SARTimeAzimuthResolution Double m/sec Azimuth resolution time product.
SARMaxSceneWidth Double m Maximum scene width.
SARIntegrationTime Double sec The fixed integration time or time to achieve the desired azimuth resolution, depending on the setting of the analysis mode when defining the radar. This constraint and the Azimuth Resolution constraint are mutually exclusive.
SARAzimuthResolution Double m The fixed azimuth resolution or the resolution achievable within the desired integration time, depending on the setting of the analysis mode when defining the radar. This constraint and the Integration Time constraint are mutually exclusive.
SARRangeResolution Double m The coverage rate of the SAR. Enter Min and/or Max area rate as the ratio of the selected distance unit squared to the selected time unit.
SARAreaRate Double m2/sec The coverage rate of the SAR. Enter Min and/or Max area rate as the ratio of the selected distance unit squared to the selected time unit.
SARSNR Double dB Signal-to-noise ratio for the SAR radar.
SARSCR Double dB Signal-to-clutter ratio for the SAR radar.
SARCNR Double dB Clutter-to-noise ratio for the SAR radar.
SARPTCR Double dB The point target-to-clutter ratio for the SAR radar.
SAREffectiveNoiseBackScatter Double dB Effective noise backscatter.
SARNoiseBandwidth Double Hz Radar receiver noise bandwidth.
SARNoisePower Double dBw Radar receiver noise power.
SARSNRUnderJamming Double dB Signal to noise ratio under jamming.
SARSCRUnderJamming Double dB Signal to clutter ratio under jamming.
SARCNRUnderJamming Double dB Clutter to noise ratio under jamming.
SARJOverS Double dB Jamming to signal ratio (J/S).
SARJammingPower Double dBw Total jamming power.

Output Arguments

The following table gives representation (data type) and, where applicable, unit information on each of the output arguments for the SAR Constraint plugin point.

Name Representation Units Definition
Constraint Double --- A value returned by the script to STK Access at this time instant. STK applies the Min and Max constraint criteria and the Exclude Interval flag (if checked) to this value to determine access availability.

Radar Cross Section (RCS)

The Radar Cross Section plugin computes the aspect dependent RCS values for each time step in a radar computation.

For more information, see Radar Cross Section Theta/Rho Definitions.

Input Arguments

The following table gives representation (data type) and, where applicable, unit information on each of the input arguments for the Radar Cross Section plugin point.

Name Representation Units Definition
EpochSec Double sec The scenario simulation epoch time.
Frequency Double Hz The doppler shifted receive frequency at the radar target.
IncidentRho Double rad Incident rho angle. The rho angle is defined as the total angle between the target body z-axis and the incident body fixed vector.
IncidentTheta Double rad Incident theta angle. The theta angle is defined as the angle between the target body x axis and the incident body fixed vector projection onto the target body xy plane.
ReflectedRho Double rad Reflected rho angle. The rho angle is defined as the total angle between the target body z-axis and the reflected body fixed vector.
ReflectedTheta Double rad Reflected theta angle. The theta angle is defined as the angle between the target body x axis and the reflected body fixed vector projection onto the target body xy plane.
IncidentBodyFixedVector Double-3 m The incident vector from the transmit radar to the target in the target body fixed coordinate system.
ReflectedBodyFixedVector Double-3 m The reflected vector from the target to the receive radar in the target body fixed coordinate system.

Output Arguments

The following table gives representation (data type) and, where applicable, unit information on each of the output arguments for the Radar Cross Section plugin point.

Name Representation Units Definition
RCSMatrixReal00 Double sqm The real part of the (0,0) value of the 2x2 complex RCS matrix.
RCSMatrixImg00 Double sqm The imaginary part of the (0,0) value of the 2x2 complex RCS matrix.
RCSMatrixReal01 Double sqm The real part of the (0,1) value of the 2x2 complex RCS matrix.
RCSMatrixImg01 Double sqm The imaginary part of the (0,1) value of the 2x2 complex RCS matrix.
RCSMatrixReal10 Double sqm The real part of the (1,0) value of the 2x2 complex RCS matrix.
RCSMatrixImg10 Double sqm The imaginary part of the (1,0) value of the 2x2 complex RCS matrix.
RCSMatrixReal11 Double sqm The real part of the (1,1) value of the 2x2 complex RCS matrix.
RCSMatrixImg11 Double sqm The imaginary part of the (1,1) value of the 2x2 complex RCS matrix.
ScatterMatrixBasis Integer --- RCS scattering basis. Value 0 indicates that the scattering matrix defines the LHC and RHC polarization orthogonal basis. Value 1 indicates that the scattering matrix defines the vertical and horizontal polarization orthogonal basis.

Using the Vector Geometry Tool as an Input Source

All Vector Geometry Tool inputs are also available for all STK Communications and STK Radar plugin scripts. For information on requesting an input from the Vector Geometry Tool, see Vector Geometry Tool Plugin Points.

STK 11.2.1 Programming Interface