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Chapter 3 - Software Features
Given these parameters, the Master Control CCA calculates the required turret line-of-sight pointing angles relative
to the aircraft.
For estimating target location, the following parameters are known:
•
Terrain elevation
•
Aircraft lat/long
•
Aircraft altitude
•
Aircraft orientation
•
Turret line-of-sight pointing angles relative to the aircraft
Given these parameters, the Master Control CCA calculates the target lat/long and slant range.
In both types of calculations, aircraft orientation (pitch, roll and true heading) is used to reference the turret line-of-
sight to the Earth coordinate system.
Target
Altitude
is Zero
IR Digital Video Processing
The IR video processor is a circuit card assembly that interfaces with the IR sensor. The processor performs two
main functions:
•
Optimization of video quality
•
Conversion of a digital to analog signal
The IR sensor outputs raw, thermal image data over a HotLink™ digital interface. The IR video processor optimizes
the raw image data in three phases. To balance the thermal quality of the image, the first optimization applies pixel
uniformity correction – stored in a software Non-Uniformity Correction (NUC) table that is defined by either a 1-Point
or 2-Point calibration of the IR sensor. To provide a complete thermal image, a second optimization interpolates
missing pixels and fills in that data to remove sensor artifacts. To sharpen image edges and set proper exposure,
the IR video processor applies an image sharpening algorithm followed by a histogram equalization to maximize the
dynamic tonal range of the image. As a final conversion step, the optimized digital data is converted into analog
video output that is compliant with a video standard (either NTSC or PAL). The converted video is routed to the
video switch matrix for overlay annotations and final video display output.
October 2007
66
Curvature of
Earth's Surface
Figure 3-6 Aircraft & Target Locations
Slant
Range
Aircraft
Altitude
90
Aircraft
Latitude &
Longitude
TM00358 Rev. A
L-3 WESCAM
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