ATP-3-09-12 Field Artillery Counterfire and Weapons Locating Radar Operations Download
Page 129 of 150
AN/TPQ-36 Weapons Locating Radar Systems Characteristics and Employment 26 October 2021 ATP 3-09.12 J-15 registration point expressed up to the next 10 meters. The radar must be able to observe this point and begin tracking the trajectory of the round at least 350 meters before the burst. This ensures the AN/TPQ-36 can track the round to the burst point. If the radar cannot observe the orienting point, the radar operator will be notified by an error message. J-61. The radar section chief must then coordinate with the firing unit to select a new high-burst altitude (or orienting point for the WLR) that meets the technical tracking criteria of the radar. The radar operator passes the grid coordinates and altitude of each observed burst to the firing unit. The firing unit must then determine registration corrections as it would for a regular high-burst registration. IMPACT-PREDICT REGISTRATION J-62. In an impact-predict mission, the WLR uses friendly fire mode to track the round on its descending trajectory toward the registration point and to predict where the round will impact without actually observing the ground burst. To provide data, the WLR must track the round along its trajectory for a sufficient distance above the radar's screening crest. If the WLR cannot track the round far enough along its trajectory, it will notify the operator that it has limited track coverage. J-63. Coordination must then be made with the firing unit to end the mission or to continue it by selecting a new registration point. The predicted burst locations are reported to the fire direction center, which then averages them as "did hit" data and compares them to the fired "should hit" data of the registration point to obtain the mean POI registration corrections. DATUM-PLANE REGISTRATION J-64. The datum-plane registration is a lesser-used capability of WLRs. A datum (geodetic) is a reference surface consisting of five quantities: the latitude and longitude of an initial point, the azimuth of a line from that point, and the parameters of the reference ellipsoid (JP 2-03). During a datum-plane registration, the fire direction center selects a registration point, for example, a grid intersection. The altitude for the datum-plane registration is the altitude of a selected horizontal datum plane above the registration point through which all rounds will pass. The WLR must be able to observe the rounds in flight as they pass through this altitude. In calculating firing data, the fire direction center uses the altitude of the datum plane as the altitude of the registration point. If the WLR cannot track along the trajectory for a sufficient distance to its datum-plane orienting point, the same error messages will be displayed to the operator as for a high-burst registration. J-65. The firing unit must then adjust the altitude of the target. When the WLR observes the registration rounds, the coordinates reported to fire direction center are those of each penetration or intersection point of the datum plane at the datum plane altitude rather than the predicted location of impact. The fire direction center corrects the "should hit" data by the altitude difference between the datum plane and the actual registration point. The fire direction center must then compute registration corrections in the same way it would to obtain "did hit" data for a mean POI registration. Procedures for manually recording fire mission data are provided and outlined under the friendly fire log.