OVERVIEW: The AN/WLR-1 is a U.S. Navy passive electronic support measures (ESM) system used to detect, analyze, and identify radar emissions for threat warning and situational awareness. Installed on a wide range of surface ships and submarines since the 1960s, it supports electronic warfare by cueing defensive systems without active signal emission.

GENERAL DESCRIPTION: The AN/WLR-1 is a passive shipboard Electronic Support Measures (ESM) system used to detect, intercept, and analyze radar emissions. It helps naval vessels identify potential threats by characterizing radar signals such as frequency, direction, and scan patterns without emitting any signals itself. Used primarily for situational awareness and threat warning, it supports electronic warfare operations by cueing jammers or defensive systems and contributes to building the ship’s electronic order of battle. Designed for continuous operation in high-threat environments, it has been a core component of U.S. Navy surface and subsurface platforms since the 1960s 

ROLE SUMMARY:
Category: Electronic Support Measures (ESM) / Radar Warning Receiver (RWR)
Primary Use: Detection, classification, and analysis of radar threats
Function: Passive signal collection and tactical cueing
Platform: Installed on U.S. Navy aircraft carriers, cruisers, destroyers, frigates, and submarines
Export: Used by allied navies through ship transfers or joint programs
Integration: Works in conjunction with onboard radar, fire-control, and electronic countermeasure systems

Type: Shipborne Electronic Support Measures (ESM) / Radar Warning Receiver (RWR)
Platform Types: Carriers, cruisers, destroyers, frigates, submarines (U.S. Navy and allied ships)

See Specific information under [Sensors/EW] section.

SOURCES:
U.S. Navy Fact Files
Military Periscope
GlobalSecurity.org