WSF_OTH_RADAR_SENSOR

sensor WSF_OTH_RADAR_SENSOR

sensor <name> WSF_OTH_RADAR_SENSOR
   ... Platform Part Commands ...
   ... Articulated Part Commands ...
   ... sensor Commands ...

   show_calibration_data
   mode <name>
     ... sensor Common Mode Commands ...
     ... WSF_RADAR_SENSOR Mode Commands ...

      beam 1
         Antenna Commands ...
         transmitter
           ... transmitter commands ...
         end_transmitter
         receiver
           ... receiver commands ...
         end_receiver
         ... WSF_RADAR_SENSOR Beam Commands ...
         ... OTH Beam Commands ...
      end_beam
      beam <n>
         Antenna Commands ...
         transmitter
           ... transmitter commands ...
         end_transmitter
         receiver
           ... receiver commands ...
         end_receiver
         ... WSF_RADAR_SENSOR Beam Commands ...
         ... OTH Beam Commands ...
      end_beam
   end_mode
end_sensor

Overview

WSF_OTH_RADAR_SENSOR provides a baseline Over-The-Horizon Backscatter (OTH-B) Skywave radar implementation. It is capable of using the ionosphere to reflect energy over the visual horizon in an attempt to detect targets. Note to analysts: This implementation is a single-bounce only sensor that is based on the Chapman Ionosphere model. This implementation focuses on a bounce in the F Region of the ionosphere, specifically the F2 Layer. This area has the highest electron density.

The OTH-B radar definition is very similar to that found in the baseline WSF_RADAR_SENSOR. The OTH Mode Commands are identical to the baseline WSF_RADAR_SENSOR Mode Commands. In addition to the baseline WSF_RADAR_SENSOR Beam Commands, new OTH specific Beam commands allow the user to define the ionospheric conditions, the solar characteristics, and the noise environment.

Please refer to WSF_RADAR_SENSOR for the Multiple Beam Considerations, Mode Commands, and Radar Beam Commands. OTH Beam Commands are discussed below.

OTH Beam Commands

noise environment <noise-environment-type>

Controls the computation of galactic noise, atmospheric noise, and man-made noise. The noise is computed and applied ONLY if the noise environment command is used. If it is not present, no additional noise is computed.

Default: quiet_rural

solar_characteristics … end_solar_characteristics

This command allows the initialization of time of day and day of year. These control the solar declination angle and the solar zenith angles used by the routine to determine if an ionospheric bounce can occur.

solar_characteristics
   hour_of_day  <int>
   day_of_year  <int>
end_solar_characteristics

The hour_of_day is based upon the 24 hour clock, and is LOCAL time. If the solar_characteristics data block is not invoked, or if day_of_year and/or hour_of_day are not specified, they each default to 1 and 12, respectively, so January 1st, 1200 hours.

ionosphere_characteristics … end_ionosphere_characteristics

This command allows the initialization of data that will control if and where an ionospheric bounce can occur.

ionosphere_characteristics
   electron_temperature                <double>
   electron_density_at_max             <double>
   electron_height_at_max              <length>
   reflection_height                   <length>
   ionosphere_constrains_minimum_range <bool>
end_ionosphere_characteristics

• electron_temperature is specified in degrees Kelvin. Default is 1540 K.

• electron_density_at_max is the highest electron density measured in electrons per cubic meter. Default is 4.0e11.

• electron_height_at_max corresponds to the height/altitude at which maximum electron density occurs. Default is 250 km.

• reflection_height height/altitude used to compute the geometry for an ionospheric bounce. This is also used to compute minimum detection range (i.e., skip-zone distance). Default is 300 km.

• ionosphere_constrains_minimum_range allows the setting of a computed minimum and maximum range. Default is set to false. If a minimum and/or maximum range is specified by the user, and ionosphere_constrains_minimum_range is set to true, then the user-defined range limits will be ignored and the computed ranges will be used. A warning statement to the user will alert them to this fact.

OTH Reflection Points

The estimated reflection point of the ionosphere can be accessed through the AuxDataDouble method on the tracks provided by the sensor.

Example:

double lat = track.AuxDataDouble("oth_reflection_point_lat");
double lon = track.AuxDataDouble("oth_reflection_point_lon");
double alt = track.AuxDataDouble("oth_reflection_point_alt");