Table of Contents
Advertisement
TM00358 Rev. A
3.4 SOFTWARE FEATURES
3.4.1
Interpretation of Operator Control
Firmware within the system interprets input command feed as operator control functions. When no thumb pressure
is applied, the slew transducer may have a significant output offset voltage. Unless compensated for, this could
make manual tracking difficult with narrow fields of view. Therefore, an Auto Null function is provided to optimize the
manual track performance.
When an auto null command is received, the Master Control firmware reads the current slew transducer signal as
zero-thumb-pressure. This reading is used as an offset that is to be applied for slew calculations. A non-linear
scaling of the slew transducer signals is implemented to assist in manual tracking. An additional aid for manual
tracking is the zoom multiplier function. When enabled, the zoom multiplier function scales the maximum angular
rate inversely with the focal length of the Video In Control. The reference focal length for zoom multiplier scaling is
40 mm on the EOW sensor.
Note: Do not enable the zoom multiplier when attempting to manually track a high crossing rate target with a long
focal length.
3.4.2
Functions Related to Target Geographic Location
The target geo-location functions assume a spherical Earth with radius of 6366.7 km (3956.1 mi). The target geo-
location functions include an approximate model of the refraction of light through the atmosphere. The model makes
the error due to bending of the light negligible relative to the other errors in the system (Turret pointing accuracy,
INS accuracy, etc.). The geo-location functions point the turret line-of-sight to a location and estimates the location
of the turret line-of-sight.
The system performs two functions involving target geographic location:
•
The turret line-of-sight is pointed to a target geographic location.
•
The geographic location of the turret line-of-sight.
For pointing to a target location, the following parameters are given:
•
Target lat/long
•
Terrain elevation
•
Aircraft lat/long
•
Aircraft altitude
•
Aircraft orientation
L-3 WESCAM
All Rights Reserved
A
Slew Transducer Force
Figure 3-5 Slew Force Interpretation
Chapter 3 - Software Features
October 2007
65
Advertisement
Table of Contents
