An extract on #aksaray
The EPP-III Diesel-Electric Power Plant (EPP) is the power source for the ECS and Radar. The EPP consists of two 150 kilowatt diesel engines with 400 hertz, 3-phase generators that are interconnected through the power distribution unit. The generators are mounted on a modified M977 HEMTT. Each EPP has two 75-gallon (280 L) fuel tanks and a fuel distribution assembly with grounding equipment. Each diesel engine can operate for more than eight hours with a full fuel tank. The EPP delivers its power to the Radar and ECS through cables stored in reels alongside the generators. Additionally, it powers the AMG via a cable routed through the ECS.
Patriot Advanced Capability (PAC-1), known today as the PAC-1 upgrade, was a software-only upgrade. The most significant aspects of this upgrade were changing the way the radar searched and the way the system defended its assets. Instead of searching low to the horizon, the top of the radar's search angle was lifted to near vertical (89 degrees) from the previous angle of 25 degrees. This was done as a counter to the steep parabolic trajectory of inbound ballistic missiles. The search beams of the radar were tightened, and while in "TBM search mode" the "flash", or the speed at which these beams were shot out, was increased significantly. While this increased the radar's detection capability against the ballistic missile threat set, it decreased the system's effectiveness against traditional atmospheric targets, as it reduced the detection range of the radar as well as the number of "flashes" at the horizon. Because of this, it was necessary to retain the search functions for traditional atmospheric threats in a separate search program, which could be easily toggled by the operator based on the expected threat. Additionally, the ballistic missile defense capability changed the way Patriot defended targets. Instead of being used as a system to defend a significant area against enemy air attack, it was now used to defend much smaller "point" targets, which needed to lie within the system's TBM "footprint". The footprint is the area on the ground that Patriot can defend against inbound ballistic missiles.
During the 1980s, Patriot was upgraded in relatively minor ways, mostly to its software. Most significant of these was a special upgrade to discriminate and intercept artillery rockets in the vein of the Multiple rocket launcher, which was seen as a significant threat from North Korea. This feature has not been used in combat and has since been deleted from U.S. Army Patriot systems, though it remains in South Korean systems. Another upgrade the system saw was the introduction of another missile type, designated MIM-104B and called "anti stand-off jammer" (ASOJ) by the Army. This variant is designed to help Patriot engage and destroy ECM aircraft at standoff ranges. It works similar to an anti-radiation missile in that it flies a highly lofted trajectory and then locates, homes in on, and destroys the most significant emitter in an area designated by the operator.