An early-warning radar is any radar system used primarily for the long-range detection of its targets, i.e., allowing defences to be alerted as early as possible before the intruder reaches its target, giving the air defences the maximum time in which to operate. This contrasts with systems used primarily for tracking or gun laying , which tend to offer shorter ranges but offer much higher accuracy.
11-580: The AN/MPQ-49 Forward Area Alerting Radar ( FAAR ) is a lightweight early warning radar system consisting of the AN/TPQ-43 radar, AN/TPX-50 Mark XII IFF receiver, a 5 kW generator set, and a Gama Goat providing mobility. FAAR was developed by the US Army in the 1960s to support their field anti-aircraft weapons, the M48 Chaparral and M163 Vulcan Air Defense System , deployed through
22-576: A Gama Goat and set up behind the front lines . The generator is towed behind the Gama Goat's own trailer, and then detached and operated at a distance from the trailer. The entire system is easily air-transportable. Early warning radar EW radars tend to share a number of design features that improve their performance in the role. For instance, EW radar typically operates at lower frequencies, and thus longer wavelengths, than other types. This greatly reduces their interaction with rain and snow in
33-444: Is greatly extended. This allows the radar to use high-frequency signals, offering high resolution, while still offering long range. A major exception to this rule are radars intended to warn of ballistic missile attacks, like BMEWS , as the high-altitude exo-atmospheric trajectory of these weapons allows them to be seen at great ranges even from ground-based radars. Shortwave radio Too Many Requests If you report this error to
44-472: The 1970s and 80's, and retired from active service in 1991. FAAR units have been used for drug trafficking surveillance in Palm Beach , and since September 1991, offered for sale to foreign users. The AN/TPQ-43 radar was mounted on a boom that extended upward from the rear of the Gama Goat's trailer. It is a pulse doppler radar that operates in the D band and has a range of about 20 km. Data from
55-545: The 50 MW range by the 1960s. Since then, improvements in receiver electronics has greatly reduced the amount of signal needed to produce an accurate image, and in modern examples the transmitted power is much less; the AN/FPS-117 offers 250 nautical miles (460 km; 290 mi) range from 25 kW. EW radars are also highly susceptible to radar jamming and often include advanced frequency hopping systems to reduce this problem. The first early-warning radars were
66-755: The British Chain Home , the German Freya , the US CXAM (Navy) and SCR-270 (Army), and the Soviet Union RUS-2 [ ru ] . By modern standards these were quite short range, typically about 100 to 150 miles (160 to 240 km). This "short" distance is a side effect of radio propagation at the long wavelengths being used at the time, which were generally limited to line-of-sight. Although techniques for long-range propagation were known and widely used for shortwave radio ,
77-620: The ability to process the complex return signal was simply not possible at the time. To counter the threat of Soviet bombers flying over the Arctic, the U.S. and Canada developed the DEW Line . Other examples ( Pinetree Line ) have since been built with even better performance. An alternative early warning design was the Mid-Canada Line , which provided "line breaking" indication across the middle of Canada , with no provision to identify
88-427: The air, and therefore improves their performance in the long-range role where their coverage area will often include precipitation. This also has the side-effect of lowering their optical resolution , but this is not important in this role. Likewise, EW radars often use much lower pulse repetition frequency to maximize their range, at the cost of signal strength, and offset this with long pulse widths , which increases
99-516: The radar was generally not used at the radar site itself, but broadcast over FM radio to the "Target Alerting Data Display Set" (TADDS), a small battery-powered receiver and display unit. Field units, including the Chaparral, Vulcan and FIM-43 Redeye units, used the TADDS as an early-warning display, aiming their optically-guided weapons in the general direction it provided. FAAR is transported by
110-459: The signal at the cost of lowering range resolution. The canonical EW radar is the British Chain Home system, which entered full-time service in 1938. It used a very low pulse repetition of 25 pps and very powerful transmissions (for the era) reaching 1 MW in late-war upgrades. The German Freya and US CXAM (Navy) and SCR-270 (Army) were similar. Post-war models moved to the microwave range in ever-increasingly powerful models that reached
121-401: The target's exact location or direction of travel. Starting in the 1950s, a number of over-the-horizon radars were developed that greatly extended detection ranges, generally by bouncing the signal off the ionosphere . Today the early warning role has been supplanted to a large degree by airborne early warning platforms. By placing the radar on an aircraft, the line-of-sight to the horizon
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