radar_signature

radar_signature <signature-name> … end_radar_signature
radar_signature <signature-name>
   use_bisector_for_bistatic <boolean-value>
   interpolate_tables <boolean-value>
   interpolation_type [linear | logarithmic]
   state <state-name> | default
      polarization [ horizontal | vertical | slant_45 | slant_135 | left_circular | right_circular | default ]
         frequency_limit <frequency-value>
            ... Azimuth-Elevation Table Definition ...
         frequency_limit <frequency-value>
            ... Azimuth-Elevation Table Definition ...

      polarization ...

      plt_file <file-name> ...

   state ...

end_radar_signature

Overview

radar_signature defines the radar signature for a platform type. The radar signature is used when a radar sensor attempts to detect a platform. The radar signature consists of one or more sets of tables where each set defines the signature (as a function of polarization and frequency) that applies when the platform is in a particular ‘state.’ A ‘state’ represents a condition such as ‘bay-doors-open.’

<signature-name> is the name to be given to the signature. If the name specifies the name of an existing definition then the new definition will replace the current one (i.e. the last occurrence will be used for the simulation.)

Commands

use_bisector_for_bistatic <boolean-value>

Specifies if a bistatic signature will be approximated for bistatic detection attempts.

  • If true, the RCS will be determined using the bisector of the target-to-transmitter and target-to-receiver aspect angles.

  • If false, the RCS will be determined using the target-to-receiver aspect angle.

Default true

interpolate_tables <boolean-value>

Specifies whether to apply interpolation to the defined Azimuth-Elevation Table Definition. The type of interpolation can be either linear or logarithmic (see interpolation_type).

Default true

interpolation_type <linear | logarithmic>

Specifies whether to use linear or logarithmic interpolation when interpolating data in the azimuth elevation tables.

Default linear

state [ <state-name> | default ]

Indicates that the following table definitions will be used when the platform is in the signature state <state-name>.

If default is specified then the subsequent table(s) will be used if the platform is in a signature state that does not match any of the states defined in the signature.

If a state command is not specified, then the signature has one set of tables that applies to all signature states.

polarization [ horizontal | vertical | slant_45 | slant_135 | left_circular | right_circular | default ]

Indicates that the following table(s) (up to the next polarization or state) are to be used when the sensing radar is operating with the specified polarization.

If polarization is omitted then the following table(s) (up to the next state) are applicable to any polarization.

frequency_limit <frequency-value>

Indicates the upper frequency bound to which the following table applies. These must occur in increasing order within a single state/polarization grouping. For a radar is operating with a particular polarization and frequency, the table selected will be the first one with the proper state and polarization where the frequency less than frequency_limit.

If frequency_limit is omitted then the following table applies to all frequencies.

plt_file <file-name> [default <horizontal | vertical>]

Loads a PLT file, in either 3- or 5-column format, that includes multiple Az/El table definitions indexed by polarization and frequency. Because the polarization and frequency are embedded within the file, any previous polarization or frequency_limit command will be ignored. Optionally, a polarization (horizontal or vertical) to be used as the default may be specified. However, since every state must have a default polarization, if this optional argument is omitted, one must be defined explicitly using the polarization command.

Note

Only horizontal and vertical polarizations are currently accepted within the PLT file.

Note

The frequencies specified in plt_files are center frequencies, not frequency limits. For an EM interaction at a specific frequency, the table will be chosen based on a frequency band about the center frequency, not based on frequency limits. For example,consider a a plt_file with frequency-indexed tables at 0.1, 1, and 10 GHz. In this case EM interactions between 0 and 0.55 GHz will use the first table, interactions between 0.55 and 5.5 GHz use the second table, and interactions at 5.5 GHz and above use the third table.

Examples

Inline table:

radar_signature AIRPLANE_RADAR_SIG
  state default
     inline_table dbsm 20 2
               -90.0  90.0
       -180.0    0.0   0.0
       -137.5    0.0   0.0
       -135.0   20.0  20.0
       -132.5    0.0   0.0
        -92.5    0.0   0.0
        -90.0   20.0  20.0
        -87.5    0.0   0.0
        -47.5    0.0   0.0
        -45.0   20.0  20.0
        -42.5    0.0   0.0
         42.5    0.0   0.0
         45.0   20.0  20.0
         47.5    0.0   0.0
         87.5    0.0   0.0
         90.0   20.0  20.0
         92.5    0.0   0.0
        132.5    0.0   0.0
        135.0   20.0  20.0
        137.5    0.0   0.0
        180.0    0.0   0.0
     end_inline_table
end_radar_signature

Bistatic Signature

bistatic_signature … end_bistatic_signature

Defines a bistatic radar signature for a platform type. This signature is used for bistatic interactions (i.e. interactions involving a transmitter and receiver not colocated). This input block is defined within the radar_signature block and defines a separate table to be used for bistatic interactions RCS lookups.

Note

If a ‘bistatic_signature’ is defined then the bistatic signature will override the use_bisector_for_bistatic command.

Note

If a ‘radar_signature’ is not defined and a ‘bistatic_signature’ is then the bistatic signature will be used for monostatic interactions also with the same receive and transmit angles used for lookups.

...
   bistatic_signature
      interpolate_transmitter_angles <boolean-value>
      transmitter_angles_interpolation_type [ linear | logarithmic ]
      state <state-name> | default
         polarization [ horizontal | vertical | left_circular | right_circular | default ]
            frequency_limit <frequency-value>
               azimuth <angle-value>
                  elevation <angle-value>
                     ... Azimuth-Elevation Table Definition ...
                  elevation ...
               azimuth ...
            frequency_limit ...

         polarization ...

         azimuth <angle-value>
            elevation <angle-value>
               plt_file <file-name> ...
            elevation ...
         azimuth <angle-value> ...

      state ...
   end_bistatic_signature
...
interpolate_transmitter_angles <boolean-value>

Specifies whether or not to interpolate between the tables for the specified target->transmitter angles. If ‘false’ then the next lower azimuth/elevation angle table is used for the given target->transmitter azimuth/elevation pair.

Default false

transmitter_angles_interpolation_type <linear | logarithmic>

Specifies whether to use linear or logarithmic interpolation when interpolating target->transmitter angles.

Default linear

azimuth

Specifies the minimum target->transmitter azimuth angle, between [-180.0, 180.0] degrees, for the entered table. Must specify at least two monotonically increasing angles with tables. Tables are a function of the target->receiver angles.

elevation

Specifies the minimum target->transmitter elevation angle, between [-90.0, 90.0] degrees, for the entered table. Must specify at least two monotonically increasing angles. Tables are a function of the target->receiver azimuth/elevation angles.