OVERVIEW: ESM Systems are passive electronic support platforms designed to detect, identify, and analyze radar and communication emissions for situational awareness and threat warning.

GENERAL DESCRIPTION: Typical 1980s ESM systems operate by intercepting electromagnetic signals emitted by radars and radios, extracting key parameters such as frequency, pulse repetition interval, and signal strength to classify and identify emitters. These systems provide early warning and threat assessment for naval, airborne, and ground platforms, supporting tactical decision-making and electronic countermeasures. Processing was primarily analog or early digital, with limited real-time geolocation capabilities.

ROLE SUMMARY:
Category: Electronic Support Measures (ESM)
Primary Use: Radar and communications emitter detection and identification
Function: Passive signal interception and analysis
Platform: Naval vessels, aircraft, ground stations
Integration: Interfaces with EW suites and command systems for threat alerting

See Specific information under [Sensors/EW] section.

SOURCE:
U.S. Navy EW Historical Documents
https://en.wikipedia.org/wiki/Electronic_support_measures