Define power spectrum filters for transmitters and receivers (Deprecated Command)
Comm <CommObjectPath> Filter {On | Off | Define} [{FilterType} <UpperBandLimit> <LowerBandLimit> <InsertionLoss> {AdditionalParams}]
Note: This command was deprecated in STK 9, it should no longer be used. This command has been replaced by the Receiver and Transmitter commands.
The Comm Connect commands were enhanced in STK 9 to make use of attributes and to simplify the format required to use these commands. For more information on using the new format see Transitioning to the New Transmitter Format and Transitioning to the New Receiver Format.
The Comm Filter command allows you to define the power spectrum filters for transmitters and receivers.
The optional filter parameters are only entered if Define is entered. These parameters are described in the table below.
| Filter Parameters | Description |
|---|---|
| {FilterType} | Valid values are: Bessel, Sinc, Chebyshev, Butterworth, Elliptic, RCLowPass, Rectangular, FIR, FIR_BoxCar, IIR, CosineWindow, GaussianWindow, HammingWindow, External |
| <UpperBandLimit> | This is the upper band limit frequency of the filter. This value is relative to the carrier frequency (the carrier being at zero Hz). The upper limit is considered as a sharp cutoff point and spectrum is zero beyond the limit. This value is entered in Scenario bandwidth units and must be between 0.0 and 1e15 Hz. |
| <LowerBandLimit> | This is the lower band limit frequency of the filter. This value is relative to the carrier frequency. This sets the lower limit with a sharp cutoff point for the spectrum. This value is entered in Scenario bandwidth units and must be between -1e15 and 0.0 Hz. |
| <InsertionLoss> | A fixed signal attenuation in addition to the spectral loss computed by the filter's response characteristics. This value is entered in dB, and must be between 0.0 and 1000 dB. |
The {AdditionalParams} are dependent on the type of Filter being defined. These parameters are described in the table below.
| {FilterType} | {AdditionalParams} | Description |
|---|---|---|
|
N/A | N/A |
|
<FilterOrder> <CutoffFreq> |
<FilterOrder> is the integer value corresponding to the filter order, higher order filters generally have sharper roll-offs at the cut off frequencies. This value should be between 1 and 1000. <CutoffFreq> specifies the -3dB (50 percent) filter attenuation response point. This value is entered in Scenario bandwidth units and should be between 0.0 and 1e15 Hz. |
|
<FilterOrder> <SamplingFreq> |
<FilterOrder> is the integer value corresponding to the filter order, higher order filters generally have sharper roll-offs at the cut off frequencies. This value should be between 1 and 1000. <SamplingFreq> specifies the rate at which the discrete filter is sampling the input. This value is entered in Scenario bandwidth units and should be between 0.0 and 1e15 Hz. |
|
<CutoffFreq> | <CutoffFreq> specifies the -3dB (50 percent) filter attenuation response point. This value is entered in Scenario bandwidth units and should be between 0.0 and 1e15 Hz. |
|
<FilterOrder> <CutoffFreq> <Ripple> |
<FilterOrder> is the integer value corresponding to the filter order, higher order filters generally have sharper roll-offs at the cut off frequencies. This value should be between 1 and 1000. <CutoffFreq> specifies the -3dB (50 percent) filter attenuation response point. This value is entered in Scenario bandwidth units and should be between 0.0 and 1e15 Hz. <Ripple> is the peak-to-peak ripple of the filter expressed in dB, it should be between 0 and 1000 dB. |
|
<SamplingFreq> {RealCoeff | ComplexCoeff} <PolyOrder> <PolyValues> |
<SamplingFreq> specifies the rate at which the discrete filter is sampling the input. This value is entered in Scenario bandwidth units and should be between 0.0 and 1e15 Hz. <PolyValues> are the polynomial coefficient values. In the case of RealCoeff, the number of values supplied must be <PolyOrder> + 1. In the case of ComplexCoeff, the number of values must be (<PolyOrder> + 1) * 2 |
|
<SamplingFreq> {NumPolyType} <NumPolyOrder> <NumPolyValues> {DenomPolyType} <DenomPolyOrder> <DenomPolyValues> |
<SamplingFreq> specifies the rate at which the discrete filter is sampling the input. This value is entered in Scenario bandwidth units and should be between 0.0 and 1e15 Hz. {NumPolyType} <NumPolyOrder> <NumPolyValues> define the numerator. Valid values for {NumPolyType} are RealCoeff or ComplexCoeff. In the case of RealCoeff, the number of NumPolyValues supplied must be <NumPolyOrder> + 1. In the case of ComplexCoeff, the number of NumPolyValues must be (<NumPolyOrder> + 1) * 2 {DenomPolyType} <DenomPolyOrder> <DenomPolyValues> define the denominator. Valid values for {DenomPolyType} are RealCoeff or ComplexCoeff. In the case of RealCoeff, the number of DenomPolyValues supplied must be equal to <DenomPolyOrder>. In the case of ComplexCoeff, the number of DenomPolyValues must be (<DenomPolyOrder> * 2). |
|
"<FilePath>" | Enter the FilePath of the external filter file. If the filter file resides in the scenario directory only the filename itself needs to be supplied. Otherwise, a fully qualified path must be supplied. |
To turn on the filter for Transmitter1:
Comm */Facility/Facility1/Transmitter/Transmitter1 Filter On
To turn off the filter for Transmitter1:
Comm */Facility/Facility1/Transmitter/Transmitter1 Filter Off
To set the filter for Transmitter1 to Butterworth:
Comm */Facility/Facility1/Transmitter/Transmitter1 Filter Define Butterworth 20 -20 0 4 10
To set the filter for Transmitter1 to FIR_BoxCar:
Comm */Facility/Facility1/Transmitter/Transmitter1 Filter Define FIR_BoxCar 10 -10 0 8 20
To set the filter for Transmitter1 to Sinc:
Comm */Facility/Facility1/Transmitter/Transmitter1 Filter Define Sinc 20 -20 0 2
To set the filter for Transmitter1 to Chebyshev:
Comm */Facility/Facility1/Transmitter/Transmitter1 Filter Define Chebyshev 10 -10 0 4 2 1
To define an FIR filter using real coefficients:
Comm */Facility/Facility1/Transmitter/Transmitter1 Filter Define FIR 20 -20 0 10 RealCoeff 5 1.0 1.0 1.0 1.0 1.0 1.0
To define an IIR filter using complex coefficients to define the numerator and real coefficienst to define the denominator for Transmitter1:
Comm */Facility/Facility1/Transmitter/Transmitter1 Filter Define IIR 20 -20 0 10 ComplexCoeff 2 0.0605 0.0 0.121 0.0 0.0605 0.0 RealCoeff 2 1.194 -0.436
To define the filter for Transmitter1 to use an external file:
Comm */Facility/Facility1/Transmitter/Transmitter1 Filter Define External 20 -20 0 "C:\myFilter.filter"
If activated, Connect returns an acknowledgement message.
This command belongs to the following group(s):
9.0
STK Programming Interface 11.0.1