Fire-control radar

A fire-control radar (FCR) is a radar that is designed specifically to provide information (mainly target azimuth, elevation, range and range rate) to a fire-control system in order to calculate a firing solution (i.e., information on how to direct weapons such that they hit the target(s)). A typical radar emits a narrow, intense beam of radio waves to ensure accurate tracking information and to minimize the chance of losing track of the target. Some modern radars have a track-while-scan capability, enabling them to function simultaneously as both fire-control radar and search radar. This works either by having the radar switch between sweeping the search sector and sending directed pulses at the target to be tracked, or by using a phased-array antenna to generate multiple simultaneous radar beams that both search and track.

Fire-control radars operate in three different phases:

The performance of a fire-control radar is determined primarily by two factors: radar resolution and atmospheric conditions. Radar resolution is the ability of the radar to differentiate between two targets closely located. The first, and most problematic, is gaining high-range resolution. To do this in a basic fire-control radar system, it must operate at smaller pulse width. Bearing resolution is typically ensured by using a narrow (one or two degree) beam width. Atmospheric conditions, such as moisture lapse, temperature inversion, and dust particles affect radar performance as well. Moisture lapse and temperature inversion often cause ducting, in which RF energy is bent as it passes through hot and cold layers. This can either extend or reduce the radar horizon, depending on which way the RF is bent. Dust particles, as well as water droplets, cause attenuation of the RF energy, resulting in a loss of effective range. In both cases, a lower pulse repetition frequency makes the radar less susceptible to atmospheric conditions.

Most fire-control radars have unique characteristics, such as radio frequency, pulse duration, pulse frequency and power. These can assist in identifying the radar, and therefore the weapon system it is controlling. This can provide valuable tactical information, like the maximum range of the weapon, or flaws that can be exploited, to combatants that are listening for these signs. During the cold war Soviet fire control radars were often named and NATO pilots would be able to identify the threats present by the radar signals they received.

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