Zone-based attenuation

Overview

Zone-based attenuation provides the ability to do line-of-sight checks against zones. Zones can be used to represent anything, including clouds, buildings, and vegetation. If a line-of-sight check interacts with a zone, a penetration distance is calculated, which in turn is used to calculate the attenuation of the device doing the line-of-sight check.

Note

Penetration calculations are approximate. Implicit projections using latitude and longitude are employed, so that the farther the attenuation distance is from one (latitude, longitude) point to another through a zone, the more inaccurate the result will be (this is not the case for altitude differences). For that reason, one should be especially careful when implementing zone attenuation for individual zones that span degrees or more of latitude and longitude.

Requirements

In order to use Zone-based attenuation the following are required:

• Either:

  • A zone with modifiers defined that correspond with modifier_categories defined on comms and sensors (comm modifier_category and sensor modifier_category).

  • An ESRI Shape file (.shp) (loaded into WSF as a zone_set), with corresponding input of an attenuation_parameters block.

• At least one sensor or comm device. See documentation for the device you intend to use for instruction on how to set up the attenuation modifier. Multiple devices can be defined, each with separate attenuation modifiers (comm modifier_category and sensor modifier_category)

Examples

sensor los_geo_sensor WSF_GEOMETRIC_SENSOR
    azimuth_field_of_view -180.0 degrees 180.0 degrees
    elevation_field_of_view -90.0 degrees 90.0 degrees
    minimum_range 0 m
    maximum_range 100000 m
    on
    frame_time              0.5 sec
    reports_location
    ...
    modifier_category test_los_category
end_sensor

modifier_category is the keyword necessary to define the attenuation category assigned to this sensor.

test_los_category is the name of the category and will be used in the zone_set block.

comm voice_comm_base WSF_RADIO_TRANSCEIVER
    modifier_category test_comm_category
    network_name patrol_voice_base
    transfer_rate 100 mbits/sec
    transmitter
      ...
    end_transmitter
    receiver
     ...
    end_receiver
 end_comm

modifier_category is the keyword necessary to define the attenuation category assigned to this comm.

test_comm_category is the name of the category and will be used in the zone_set block.

zone_set zoneSetName
   attenuation_parameters
      file buildingShapeFile
      height_parameter ""
      constant_height 50 ft
      comm_modifier  test_comm_category 0.1
      sensor_modifier test_los_category 1.0
      projection geodetic
   end_attenuation_parameters
end_zone_set