ATP-3-09-12 Field Artillery Counterfire and Weapons Locating Radar Operations Download
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Appendix D D-2 ATP 3-09.12 26 October 2021 TRACK VOLUME D-2. The amount of track volume is determined by the vertical scan of the WLR and the amount of vertical scan that is lost because of the terrain contour, or screening crest in front of the WLR. From any WLR position, the altitude of the screening crest along the terrain contour in front of the position will vary across the WLR's sector of search. This varying screening crest altitude results in varying mask angles along the terrain contour. The variance between the smallest mask angle and the largest mask angle reduces the WLR's vertical scan. D-3. Sometimes this reduction is enough that the available scan coverage is less than the 50 mils track volume required by the WLR to extrapolate weapon locations. When the track volume is reduced below 50 mils, the radar section leader must compensate by artificially adjusting the low mask angle, narrowing the search sector, or by moving the WLR to a new position that provides adequate track volume. D-4. Whenever possible, an aiming circle or other accurate measuring device should be used to determine mask angles along the terrain contour. These measured mask angles are entered in the computer to depict the terrain contour. Otherwise, the WLR will radiate into hill masses that are higher than the flat mask default in the radar computer. Automatic terrain following can be used when digital terrain is available for the WLR site. Radar terrain following is used when the radar does not have digital terrain. Radar terrain following is a process of the WLR radiating in each sector to determine the mask angle. This capability allows the radar section leader to compute mask angles before occupying a radar site. TRACK VOLUME CALCULATION AND SUBSEQUENT ACTIONS D-5. The WLR search fence starts at the lowest mask angle entered in the radar computer (or at the flat mask default value if no lowest mask angle is entered) and goes to the highest point of the vertical scan. The first step in calculating track volume for the WLR site and search sector is to subtract the low mask angle from the high mask angle. This difference must then be subtracted from the vertical scan of the WLR. The result is the track volume for the WLR site. Figure D-2, on page D-3, shows the procedure for calculating track volume.