The Angle-Off-Boresight Format
Use the format in this topic to create an angle-off-boresight pattern to model a sensor's field-of-view limitations. After you create the pattern, you can save it to a pattern file. You can then import the pattern file into STK, which will read the description contained in the pattern file when the file is referenced by a sensor.
As an example for this topic, you could use the angle-off-boresight format to create a sensor with the following specifications:
- The sensor is pointing off the right side of a vehicle with a beam from 40 degrees to 60 degrees off nadir.
- The sensor sweeps forward and aft 30 degrees.
- It is assumed that the vehicle's attitude is such that the vehicle X axis is along the velocity direction, which means that the custom sensor pattern is centered around a vehicle azimuth of 90 degrees.
- The sensor is designed so that the reference direction (boresight) is along nadir and, therefore, is outside of the pattern.
After you create the pattern, you can save it to a pattern file. You can then import the pattern file into STK. STK will read the description contained in the pattern file when the file is referenced by a sensor.
The accuracy of computations performed using custom sensors is directly related to the number of points used to describe the pattern. It is generally better to spend additional time generating a well-defined pattern than to be uncertain of the fidelity of the results.
In the angle-off-boresight format, the custom sensor pattern is defined by the angle between the edge points of the sensor and the boresight direction. The custom pattern can be determined from a polar diagram where the concentric circles are lines of constant angle from the boresight. The angle-off-boresight format is an alternative to the reference plane format and provides for the input of the elevation sweep angles and the forward and aft sweep angles directly.
Polar projection for the angle-off-boresight format
The pattern file is now created using the edge points and making the first and last points the same to close the pattern.
| Field | Description |
|---|---|
| NumberPoints | Enter the total number of data points in the file. |
|
InterpolateAzElPts (optional) |
STK defaults to adding more data points when your existing points are greater than a user-specified angular distance (default of 3 degrees) apart. If this is your choice, you can just leave this field out of the file. To prevent STK from adding interpolated data points, include this field with a value of No. |
| HalfAngleAzimuthData | Provide the angle-off-boresight/azimuth pairs. The first point and the last point must be the same so that the sensor pattern is closed. |
| EndPatternData |
You must have this keyword at the end of the file. |
Angle-off-boresight pattern
stk.v.12.5
NumberPoints 27
HalfAngleAzimuthData
40 60
40 65
40 70
40 75
40 80
40 85
40 90
40 95
40 100
40 105
40 110
40 115
40 120
60 120
60 115
60 110
60 105
60 100
60 95
60 90
60 85
60 80
60 75
60 70
60 65
60 60
40 60
EndPatternData