Subsystem location, orientation, slewing and scanning¶
Overview¶
The following subcommands are common to the definitions of communication, sensor, and weapon subsystems. They define the location, orientation, slewing and scanning limits, and field-of-view of the object with respect to the host platform.
Defining the nominal subsystem location and orientation¶
These commands define the subsystem coordinate frame (i.e., the coordinate frame about which the sensor can slew or scan).
location <x> <y> <z> <length-units>
yaw <angle>
pitch <angle>
roll <angle>
Defining the slewing mode and limits¶
The slewing mode (and the corresponding limits) defines the ability of a subsystem to respond to cue. If a system is not cued then it is oriented in the direction specified by yaw, pitch, and roll.
slew_mode [ fixed | azimuth | elevation | both ]
Indicates how the subsystem can respond in response to a cue:
fixed The system cannot be cued. This is the default.
azimuth The system can be cued only in azimuth.
elevation The system can be cued only in elevation.
both The system in both azimuth and elevation.
Default: fixed
azimuth_slew_limits <min-angle-value> <max-angle-value>
Specify the minimum and maximum angle about which the subsystem can be slewed in azimuth. These values are applicable only if slew_mode is azimuth or both. The limits are specified in the subsystem coordinate frame.Default: -180.0 degrees to 180 degrees
elevation_slew_limits <min-angle-value> <max-angle-value>
Specify the minimum and maximum angle about which the subsystem can be slewed in elevation. These values are applicable only if slew_mode is elevation or both. The limits are specified in the system coordinate frame.Default: -90.0 degrees to 90 degrees
Define the scanning mode and limits¶
Scanning is the process of systematically searching about the current cue (or the nominal subsystem coordinate frame if no cue is defined).
scan_mode [ fixed | azimuth | elevation | both ]
Indicates how the subsystem scans in respect to the current cue:
fixed The subsystem does not move. This is the default.
azimuth The subsystem scans only in azimuth.
elevation The subsystem scans only in elevation.
both The subsystem scans in both azimuth and elevation.
Default: fixed
azimuth_scan_limits <min-angle-value> <max-angle-value>
Specify the minimum and maximum angle about which the subsystem can scan in azimuth. These values are applicable only if scan_mode is azimuth or both. The limits are with respect to the current cue.Default: -180.0 degrees to 180 degrees.
elevation_scan_limits <min-angle-value> <max-angle-value>
Specify the minimum and maximum angle about which the subsystem can be scan in elevation. These values are applicable only if scan_mode is elevation or both. The limits are with respect to the current cue.Default: -90.0 degrees to 90 degrees
Defining the field-of-view¶
The field of view definition (azimuth, elevation, and range) is totally optional. If the target object is outside the field of view then the remainder of the computations for the communication, jamming or sensing opportunity can be bypassed.
azimuth_field_of_view <min-angle-value> <max-angle-value>
Specify the minimum and maximum angle about which the subsystem can see in azimuth. The limits are with respect to the current cue. In general these values should be greater than or equal to the azimuth_scan_limits (possibly accounting for the width of the beam when the subsystem is positioned to its scan limit).Default: -180.0 degrees to 180 degrees.Note: This value is only used for initial screening to determine if the object can potentially interact with another object.
elevation_field_of_view <min-angle-value> <max-angle-value>
Specifies the minimum and maximum angle about which the subsystem can see in elevation. The limits are with respect to the current. In general these values should be greater than or equal to the azimuth_scan_limits (possibly accounting for the width of the beam when the subsystem is positioned to its scan limit).Default: -90.0 degrees to 90 degrees.Note: This value is only used for initial screening to determine if the subsystem can potentially interact with another object.
minimum_range <length-value>
Specify the minimum range at which the system can interact with another object.Default: 0 meters.Note: This value is only used for initial screening to determine if the subsystem can potentially interact with another object.
maximum_range <length-value>
Specifies the maximum range at which the subsystem can interact with another object.Default: infinity.Note: This value is only used for initial screening to determine if the subsystem can potentially interact with another object.
Examples¶
The interaction of these subcommands can be confusing. This section will attempt to provide some hints and examples.
A mechanically-scanned ground-based early warning radar¶
A system of this type typically just rotates round and round. It does not respond to a cue, so slew_mode is fixed.
# The z coordinate gives the antenna height
location 0 0 -10 meters
# The antenna is tilted up 5 degrees from the scan plane
# Do NOT use the "pitch' command for this as it will tilt the scan plane!
antenna_tilt 5 degrees
slew_mode fixed
scan_mode azimuth
azimuth_scan_limits -180 degrees 180 degrees
A height-finding system¶
Systems of this type are typically cued to a specific azimuth and then it “nods’ up and down.
slew_mode azimuth
azimuth_slew_limits -180 degrees 180 degrees
scan_mode elevation
elevation_scan_limits 0 deg 50 deg
An acquisition system¶
A system of this type is cued to an azimuth and elevation and then searches a small volume.
slew_mode both
azimuth_slew_limits -180 degrees 180 degrees
elevation_slew_limits 0 degrees 40 degrees
scan_mode both
azimuth_scan_limits -2 degrees 2 degrees
elevation_scan_limits -2 degrees 2 degrees
A tracking system¶
This type of system is constantly being re-cued in response to a track.
slew_mode both
azimuth_slew_limits -180 degrees 180 degrees
elevation_slew_limits 0 80 degrees
scan_mode fixed
