OPS-28 is a Pulse-Doppler radar manufactured by Japan Radio. It is installed as a low-altitude warning / anti-water search radar mainly on the Maritime Self-Defense Force's escort ship. Variations include OPS-28-1, OPS-28B, OPS-28C, OPS-28D, OPS-28E and OPS-28F. The model numbers of the Maritime Self-Defense Force's electronic devices, including this machine, are generally based on the naming rules for military electronic devices of the U.S. military. It is for radar mounted on surface vessels, for detection / distance direction measurement / search.