The Sentinel radar is deployed with forward area air defense units of the US Army and USMC. The radar uses an X-band range-gated, pulse-Doppler system. The antenna uses phase-frequency electronic scanning technology, forming sharp 3D pencil beams covering large surveillance and track volume. The radar automatically detects, tracks, classifies, identifies and reports targets, including cruise missiles, unmanned aerial vehicles, rotary and fixed-wing aircraft. It uses a high scan rate (30 RPM) and offers effective coverage of 40 km. The radar is designed with high resistance to electronic countermeasures (ECM) performs target acquisition, tracking and identification. Mounted on a towed platform, it can be positioned remotely from the rest of the unit, operated autonomously and communicate with the Fire Distribution Center (FDC) via wideband fiber-optic link. Under an ongoing product modernization program, Sentinel is expected operating range to 75 km and offer improved on-board target classification capability.