Radar reconnaissance is a kind of electronic reconnaissance. The task of naval radar reconnaissance is to detect the electromagnetic radiation signal of potential threat radar at sea in peacetime by using various electronic support means and equipment such as radar reconnaissance receivers of naval vessels and carrier aircraft, and find out its radar frequency, azimuth and other technical parameters, so as to provide tactical basis for taking countermeasures and implementing interference in wartime. In wartime, it will assist satellite-borne and airborne electronic support equipment to conduct panoramic surveillance of sea and air, find out the types, quantity, configuration, deployment and changes of various enemy electronic equipment, send out alarms through threat identification, and guide ship-borne anti-radiation missiles to carry out devastating attacks on enemy radars.

Modern electromagnetic environment is extremely complex and dense. For example, during the Gulf War, the U.S. military tested the electromagnetic signals of the theater electronic warfare, and found that the signal environmental density was as high as1.20,000 ~1.50,000 pulses per second. In addition, usually in electromagnetic radiation signals, radar signals are mixed with communication signals and other various electrical signals.

Contemporary naval operations mainly occur in the offshore environment, which is a high clutter environment. The electromagnetic signals emitted offshore include not only friendly or neutral signals, but also various civil and military signals from the ground, sea and air.

The increasingly enhanced electronic anti-reconnaissance and anti-countermeasure characteristics of enemy radar in system and technology increase the complexity and difficulty of naval radar reconnaissance. It will become more difficult for naval radar reconnaissance under the bad weather and propagation conditions in the war zone or when there is enemy electronic interference. Therefore, the naval radar reconnaissance receiver must have high sensitivity, interception probability and strong sorting and processing ability, analyze and identify the real threat signal, and judge its type and threat level; In addition, according to its quantity, work situation and distribution situation, we should determine the nature and action attempt of the target and decide the measures to be taken.

At present, the advanced naval radar reconnaissance receiver in the world has an interception probability as high as 100%, and can intercept electromagnetic waves modulated by complex signals in the frequency range of 0.5 ~ 40 GHz. Its interception distance to the air is greater than the radar detection distance, the interception distance to the sea is greater than the line of sight, and the fastest signal interception time is tens of nanoseconds. Naval radar against naval radar refers to the electronic jamming of the receiving system, display system and automatic tracking system of enemy naval radar by active and passive methods. It includes active interference, passive interference and compound interference.