Situational awareness of potential hostile targets and of friendly forces is considered to be a key component in obtaining and sustaining military superiority over adversaries. Airborne Early warning and control (AWACS) aircraft provides a real-time picture of friendly, neutral, and hostile air and maritime activity under all kinds of weather and above all kinds of terrain. Information collected by AWACS can be transmitted directly from the aircraft to other users on land, at sea or in the air. In air-to-air combat, AWACS systems can communicate with friendly aircraft, extend their sensor range and give them added stealth, since they no longer need their own active radar to detect threats.The US E3 AWACS has proved to be a key to victory for the United States in the 1991, 2001, and 2003 campaigns.
US Air Force E-3 AWACS plane also participated in destroying Russian Su-24 fighter over Syria, a Russian military expert claimed in an interview with the Russian News Agency Regnum . Specialist Alexei Leonkov said that ambush operation “backstab” was done together with another E-3A AWACS (Airborne Warning and Control System) from Saudi Arabian Air Force. These two planes guided Turkish F-16 to its target together with US Patriot air defence radars and US satellite systems, said Leonkov. Specialist Leonkov explained the technical details of how the US and Saudi AWACS planes guided the Turkish F-16 to a sure missile launch in “target illumination” mode, meaning that the radar was turned off as soon as the missile rocket got into its target.
The UK Ministry of Defence (MoD) has reached a $1.98bn deal to procure a fleet of E-7 early warning radar aircraft from Boeing for the British Royal Air Force (RAF). The MoD will purchase five E-7 aircraft as a replacement for the existing Sentry aircraft. In addition, the new E-7 fleet will ensure the continued delivery of the UK’s Airborne Early Warning and Control (AEW&C) capability. The UK will become the fourth country to buy the aircraft after Australia, South Korea and Turkey. E-7 is known as ‘Wedgetail’ in Australia and has the ability to fly for long periods of time and manage battlespace from the sky. The E-7 is based on a standard Boeing 737-700 airliner modified to carry an advanced radar and 10 state-of-the-art mission crew consoles which can track airborne and maritime targets simultaneously. The RAF has been keen to secure a replacement for its fleet of six Sentry E-3D airborne warning and control system aircraft (AWACS) which have been in operation since 1992, according to the Financial Times.
Saab has rolled out the first GlobalEye Airborne Early Warning & Control (AEW&C) aircraft, an advanced, swing role airborne surveillance system based on a Global 6000 jet aircraft from Bombardier. The development and production contract was awarded at the Dubai Air Show November 2015 by the United Arab Emirates with an initial order for two systems. An additional order by the UAE for a third system was announced in 2017. The GlobalEye solution brings extended detection range, endurance and the ability to perform multiple roles with one solution, including tasks such as search & rescue, border surveillance and military operations.
Russian A-50 has participated in different campaigns over 25 years. For example, the plane was used in the operation to eliminate Dzokhar Dudayev, the leader of terrorists in the First Chechen War, on April 21, 1996. An A-50 detected Dudayev’s location by intercepting his phone call, and seconds later a Su-24 bomber destroyed the terrorist with a Kh-25 missile.
International AWACS systems
E-3 AWACS is the most widely used AWACS system in use today, used by the USAF, NATO, the RAF, French Air Force, Saudi Arabia, and the Japan Air Self-Defence Force. The US Air Force operates 33 AWACS aircraft. NATO has 17 E-3s; the United Kingdom, seven; Saudi Arabia, five; and France, four, for a total of 66. Japan has four new Boeing 767 AWACS aircraft.
NATO operates a fleet of Boeing E-3A ‘Sentry’ Airborne Warning & Control System (AWACS) aircraft equipped with long-range radar and passive sensors capable of detecting air and surface contacts over large distances. It conducts a wide range of missions such as air policing, support to counter-terrorism, evacuation operations, embargo, initial entry and crisis response. NATO AWACS are also deployed in Syria to help out in the fight against the Islamic State of Iraq and the Levant (ISIL), by providing images from its radar and identification friend or foe interrogator to ensure flight safety of coalition aircraft flying over Syria. The AWACS missions are being flown over allied airspace and international waters and providing situational awareness of the airspace over western Syria. RAF Air Cdr Paddy Teakle described the mission as “complicated” because allied and Russian aircraft are sharing the battlefield for the first time. The . A typical sortie lasts about five hours because no air-to-air refueling assets are available.
Saab rolled out its first GlobalEye airborne early warning and control (AEW&C) platform during a ceremony at the company’s Linkoping production facility in Sweden on 23 February 2018. The GlobalEye is built around the Saab Erieye Extended Range (ER) radar, and while the company has kept the external dorsal fin configuration of the original Erieye system, it has fitted it with new and largely undisclosed technology. Saab said the Erieye ER is resistant to jamming, and features a doubling of the radar’s power efficiency compared with previous Erieye iterations. It also comes with all-weather functionality in all domains (air, sea, and land surveillance), and an “extremely high” tracking update rate against targets-of-interest, according to Janes.
The company has previously given a figure of 650 km plus for the radar’s range, but being an active electronically scanned array (AESA) system means that this can be increased dramatically by focusing the energy at a particular area. The system has been said to “take the drama out of stealth” in its ability to detect low observable aircraft, Saab said.
Erieye was SAAB’s earlier AEW&C aircraft with multi-role and multi-mission capabilities for both military and civil needs. The effective surveillance area is over 500,000 sq. km horizontally and over 60,000 ft. vertically. Sea coverage is only limited by the horizon and everything from fighter aircraft, hovering helicopters, cruise missiles and Jet Ski-sized sea targets can be detected and tracked.
Different configurations of the Erieye AEW&C system have been sold to eight countries, making it one of the most widely used AEW&C systems in the world. It is in operational use in countries including Sweden, Greece, Brazil, Mexico, Pakistan, Thailand and the United Arab Emirates.
The radar is based on Active Electronically Scanned Array (AESA) technology, enabling the radar energy to be adjusted according to the situation – it can be used over an extensive area or concentrated within a smaller prioritised area. The radar detects and tracks objects quickly with high precision and a high update rate. S-band technology ensures top performance in all weather conditions
The latest iteration of the Erieye, Known as the GlobalEye swingrole surveillance system (SRSS), allows to move away from a traditional single-mission AEW&C tasking by adding further sensors that permit the platform to undertake a much broader range of missions, including those with civilian and emergency applications.
In terms of sensors, the principal item is the new Erieye ER radar, which employs gallium nitride (GaN) semiconductor technology to enhance its effectiveness over earlier generations by at least 50 per cent. AESA radars offer massively increased simultaneous search, track and targeting capabilities, frequency agility makes it harder for opponents to detect or jam. Furthermore, AESA radars offer the potential to function as high-powered jamming devices and even cyber payload insertion vectors since they are essentially software-limited at present rather than hardware limited, writes Justin Bronk, from the Royal United Services Institute (RUSI) think-tank. Also AESA arrays have a much lower number of moving parts compared to mech-scans and so are in general more reliable assuming mature software.
A FLIR Systems Star Safire 380HD electro-optic turret is installed, and the aircraft has a sensitive electronic support measures (ESM) system for passive detection. IFF and its maritime equivalent, AIS, are also incorporated. In the full-spec GlobalEye SRSS the aircraft also carries a Leonardo Seaspray 7500E AESA maritime radar, which also has overland synthetic aperture/moving target capability. During day-to-day AEW operations the platform can simultaneously carry out maritime or border surveillance duties, removing the need for a separate maritime or border patrol platform. If, for instance, a suspect vessel is detected, the GlobalEye mission commander can order the aircraft down to take a closer look with its electro-optical sensor, or alert and direct other maritime assets.
The United Instrument-Manufacturing Corporation, part of Russia’s state hi-tech corporation Rostec, is planning to deliver the fourth Beriev A-50U airborne warning and control system aircraft to the Defense Ministry before the yearend, the corporation’s spokesman told TASS. According to the spokesman, the A-50U plane features digital equipment. Unlike its predecessor, i.e. the A-50 plane, the upgraded version has an enhanced flight range. The A-50U plane is a full-fledged airborne command post. The A-50U, which made its maiden flight in 2011, is a further derivative of the A-50, which has been in service since 1989.
The plane is meant for detecting and tracking a number of aerial (fighter jets, bombers, ballistic and cruise missiles), ground (tank columns) and surface (above-water vessels) targets, informing command centers about the developments in the air and sea, and directing fighter and strike aviation.The A-50 can spot targets at a distance of 800 kilometers and has an operational range of 7,500 kilometersThe A-50 plane is in essence a giant flying data processing center. It is literally stuffed with equipment which is operated by 10 men. The aircraft can also protect itself by means of electronic warfare. It has an aerial refueling system.
China has over 20 AWACS, including the new KJ-500 ones that can track over 60 aircraft at ranges up to 470km. China already operates AEW&C aircraft, most notably the KJ-2000, which flies with the People’s Liberation Army-Air Force (PLAAF). The PLAAF currently is thought to possess five KJ-2000 AEW&C aircraft.
China has developed new KJ-500 aircraft looks more like the American AWACS (with a round radar dome on top) but is smaller and carried by the Y-9 four engine turboprop aircraft (similar to the U.S. C-130). The KJ-500 will supplement and eventually replace the current eleven KJ-200 (also called the KJ-2000), that has been in service since 2005.
The KJ-200 designs used the smaller Y-8 aircraft and a long box-like radar array on top of the aircraft. The KJ-200 radar has a range of about 300 kilometers, and the computer systems are supposed to be able to handle 5-10 fighters at a time and keep track of several dozen enemy targets. There is also four of the export model (ZDK-03) in Pakistan. Pakistan paid $300 million each for these KJ-200 variants. China had also developed AWACS on Russia, IL-76 (A-50s from Russia, converted to use Chinese KJ-200 radar systems).
Boeing E-7 AEW&C aircraft
E-7 is known as ‘Wedgetail’ in Australia and has the ability to fly for long periods of time and manage battlespace from the sky. UK Defence Secretary Gavin Williamson said: “The E-7 provides a technological edge in an increasingly complex battlespace, allowing our ships and aircraft to track and target adversaries more effectively than ever. This deal also strengthens our vital military partnership with Australia.
“We will operate state-of-the-art F-35 jets and world-class Type-26 warships, and this announcement will help us work even more closely together to tackle the global threats we face.” The aircraft is designed to track multiple airborne and maritime targets simultaneously. It can provide situational awareness and direct other assets such as fighter jets and warships.According to the MoD, the E-7 aircraft is based on the Boeing 737 NG airliner, which was modified to allow integration of a Northrop Grumman multi-role electronically scanned array (MESA) surveillance radar.
With a cruise speed of 530mph, the E-7 has a range of four million square kilometres over a period of ten hours. Other technological features included in the aircraft are multiple high-frequemcy radios, modern electronic support measures (ESM) equipment and electronic warfare self-protection (EWSP).
UK chief of the air staff air chief marshal Sir Stephen Hillier said: “This world-class capability, already proven with our Royal Australian Air Force partners, will significantly enhance our ability to deliver decisive airborne command and control and builds on the reputation of our E3D Sentry Force. “Along with defence’s investment in other cutting-edge aircraft, E-7 will form a core element of the next-generation airforce, able to overcome both current and future complex threats.” The new fleet is anticipated to enter service with the RAF in the early 2020s.
E-3 AWACS systems
The E-3 Sentry is a modified Boeing 707/320 commercial airframe with a rotating radar dome. Under normal circumstances, the aircraft operates for about eight hours, at 30,000 feet (9,150 meters) and covers a surveillance area of more than 120,000 square miles (310,798 square kilometres).
The dome is 30 feet (9.1 meters) in diameter, six feet (1.8 meters) thick, and is held 11 feet (3.3 meters) above the fuselage by two struts. The rotating dome revolves through 360 degrees every 10 seconds and is able to survey, in 10-second intervals, a volume of airspace covering more than 200,000 square miles (500,000 square km) around the AWACS, or greater than 250 miles (400 km) in all directions.
The E-3 Sentry AWACS aircraft’s capabilities include all-altitude/all-weather surveillance of the battle space; early warning of enemy actions; a real-time ability to find, fix, track, and assess airborne or maritime threats; and detection, location, and identification of electronic emitters. It also provides all-weather airborne command and control (C2), and battle-space management capability needed by commanders of U.S. and NATO air defense forces. It contains a radar subsystem that permits surveillance from the Earth’s surface up into the stratosphere, over land or water. AWACS radar has a radar range from between 200 km (for small aircraft or cruise missiles flying close to the ground) to 600 kilometers (for large aircraft flying at high altitude) well out of range of most surface-to-air missiles.
The AWACS played an important role in NATO operations such as in the United States after 9/11, in Libya and in Afghanistan.During Desert Storm, AWACS flew more than 400 missions and logged more than 5,000 hours of on-station time, providing radar surveillance and control for more than 120,000 coalition sorties. In addition to providing senior leadership with time-critical information on the actions of enemy forces, E-3 controllers assisted in 38 of the 40 air-to-air kills recorded during the conflict.
During Operation Unified Protector, the AEW&C Force also performed the crucial function of commanding and controlling all Alliance air assets operating over Libya. This included the issuing of real-time tactical orders and taskings to NATO fighter aircraft, surveillance and reconnaissance aircraft, air-to-air refuellers or unmanned aerial vehicles (UAVs). NATO E-3A aircraft also supported allied ships and submarines enforcing the maritime arms embargo against Libya by providing an aerial maritime surveillance capability.
Also on 11 February 2016, a significant milestone was reached when a NATO AWACS aircraft completed the 1,000th mission in support of NATO reassurance measures. These measures are a series of land, sea and air activities in, on and around the territory of NATO Allies in Central and Eastern Europe, designed to reassure their populations and deter potential aggression. They are taken in response to Russia’s aggressive actions to NATO’s east.
In recent years, it has been deployed on increasingly complex and demanding tactical missions, including support to maritime operations, support to counter-terrorism, close air support (CAS), airspace management, combat search and rescue (CSAR), disaster relief and counter-piracy.
AWACS command and control systems
The main AWACS operations cabin is laid out in equipment bays for communications, data and signal processing, navigation and identification equipment.The radar receivers, processing, and maintenance console are located in the cabin. The cabin equipment consists of two cabinets for the AN/APY-1 radar (digital, and analog) and three cabinets (digital, analog and maritime) for the AN/APY-2. The high power transmitter with Klystron final amplifier is located in the aft cargo section of the aircraft.
Other major subsystems in the E-3 are navigation, communications and computers (data processing). Consoles display computer-processed data in graphic and tabular format on video screens. Console operators perform surveillance, identification, weapons control, battle management and communications functions.
The radar and computer subsystems on the E-3 Sentry can gather and present broad and detailed battlefield information. Data is collected as events occur. This includes position and tracking information on enemy aircraft and ships, and location and status of friendly aircraft and naval vessels.The information can be sent to major command and control centers in rear areas or aboard ships. In time of crisis, this data can be forwarded to the National Command Authorities in the United States.
The radar has a range of more than 200 miles (320 kilometers) for low-flying targets and farther for aerospace vehicles flying at medium to high altitudes. The radar combined with an identification friend or foe subsystem can look down to detect, identify and track enemy and friendly low-flying aircraft by eliminating ground clutter returns that confuse other radar systems.
The radar uses a high Pulse Repetition Frequency (PRF) pulse Doppler waveform to distinguish aircraft targets from clutter returns. The ultra low sidelobe antenna is an important element of technology used to obtain performance over all terrains including urban and mountainous areas. The mechanical rotation of the rotodome scans the antenna beam through 360 degrees of azimuth to cover targets in all directions. Electronic scanning of the antenna beam in elevation is used for measuring target altitude and for stabilization of the beam for proper spatial coverage as the aircraft maneuvers.
The antenna is composed of slotted waveguide radiators, high power precision phase shifters for elevation beam steering and electronics for driving and control of the phase shifters. The antenna beam may be electronically scanned in the vertical dimension to obtain altitude measurements of targets. The antenna features a very high gain narrow antenna beam with ultra low sidelobes that are essential for the ability of the radar to detect small aircraft in the presence of high ground, and weather clutter as well as jamming.
AWACS Bistatic UAV
The AWACS Bistatic UAV Adjunct is a proposed $850M+ acquisition program with prototype in FY08 and completed in 2015. High Altitude Endurance (HAE) Dark Star/Global Hawk UAVs with bistatic receivers for the AWACS radar will expand area coverage of a single E-3 orbit and with the inherent significant signal to interference ratio enhancement provide increased coverage of low RCS targets while operating inside and outside an air defense threat environment.
The inclusion of the Bistatic UAV adjunct to the E-3 would allow reduced E-3 operational tempo in some theaters and the ability to cover two major regional conflicts with fewer E-3s. By only carrying the receiver, IFF interrogator and a JTIDS/JCTN transmitter package, the UAV weight limitations can be met (combat ID systems might also be included if weight and size allows). The bistatic UAV would also be able to serve as an adjunct to the E-2, TPS-75 and other air/ground radars.
Most important, the Bistatic UAV is a key part of the USAF transition from the E-3 to UAVs and Space for the AWACS mission, with the mission crew on the ground. The Bistatic UAV will be able to serve as the receiver using a satellite as the radar transmitter instead of the E-3. The bistatic UAV is a common link to a reduced E-3 fleet and use of Space for surveillance of large to LO/VLO air vehicles (missiles and aircraft) in the battlespace.
US Air Force Launches Massive Upgrade Program for AWACS Fleet
In 2015, US Air Force allocated $60 million upgrading its E-3 Sentry fleet of 32 aircraft. That milestone refers to the Next Generation Identification Friend or Foe (NGIFF) program offices installation of the AN/UPX-40 system.
“This operational installation marks a huge milestone for the AWACS program,” Nick Grudziecki, the deputy program manager, said in a release. “And it’s only the first of many.” “The UPX-40 dramatically improves the detection of weak signals or maneuvering targets at maximum range and improves detection of targets at all ranges,” Grudziecki added.
Next Generation Identification Friend or Foe (NGIFF) Program
The Next Generation Identification Friend or Foe (NGIFF) Program provides AWACS with enhanced IFF interrogator operation to add a more secure Mode 5 capability. NSA declared IFF Mode 4 unsecure and obsolete on 5 Nov 2003. The new Mode 5 interrogation capability extends the effective range of the AWACS interrogator, while helping discriminate against closely spaced cooperative targets. NGIFF will also integrate Mode S, a civilian air traffic control capability residing in the NGIFF hardware, as funding allows.
Coupled with an IFF interrogation system, the radar will be capable of detecting, identifying and tracking enemy and allied low-flying aircraft even in the presence of ground clutter signals.The IFF upgrade program, worth $60 million, is part of a larger AWACS modernization effort called Block 40/45, which includes the replacement of the AWACS’s mission computing and displays with an open system and up-to-date commercial-off-the-shelf hardware and software.
AWACS Modernization: Block 40/45 upgrade
E-3G is the first AWACS outfitted with the Block 40/45 upgrade has been deployed, complete with brand-new overhaul of the cockpit and mission control systems. The aircraft went to war utilizing large-scale upgrades that come at a cost of $2.7 billion for mission computing and communications, to handle a new generation of air warfare.
The Block 40/45 upgrade will improve integration, quality and timeliness of sensor data to the shooter, improve Combat Identification (CID), improve AWACS contribution to Time Critical Targeting via Data Link Infrastructure (DLI), improve electronic support measures processing and enable more effective, faster upgrades via an open-system, Ethernet-based architecture.
The upgrade is like moving from “an Atari to an Xbox” game system, completely modernizing how air battle managers handle sensor data. The aircraft’s systems process information with a much higher capacity and at a faster rate, both simplifying the work onboard and increasing the output.
That means more efficient control on a mission and simplified training at home because the human-machine interface is “so much more intuitive,” Skendziel said. “It takes the same amount of sensor data that was coming into the airplane before the upgrade and it allows the crew to translate that information and then to turn it out and put it out over either the radios or the data links to the joint air component at a much higher capacity and at a much faster rate,” he said. “It has really sped up the tempo on the better battle management that the E-3 crews can now produce.”Part of the Block 40/45 upgrade is replacing the aircraft’s interrogation system and modern Link 16 radios. The upgrades are driven by AWACS’ requirement to keep up with the jets it controls, as the service brings in more fifth generation fighters.
DRAGON Avionics upgrade system
The NATO E-3 fleet on an avionics upgrade system called DRAGON to move to a modern glass cockpit. The $1.4 billion program will replace the aircraft’s 40-yearold avionics with modern digital instrument displays and subsystems that meet requirements from the Federal Aviation Administration and the International Civil Aviation Organization to “keep the airframe viable in all airspaces around the world,” Skendziel said.
These upgrades, with a planned initial operational capability date of 2021, streamline operations enough that it will allow the service to eliminate the navigator position, lowering the required crew size from four to three, according to the Air Force. The cockpit upgrades will also include weather radar that predicts wind shear, an enhanced ground proximity warning system, improved engine warnings, a digital flight deck audio distribution system, and crew alert system, according to the DRAGON program offi ce release at Hanscom.
The DRAGON modifications replace the existing DMS Global Positioning System (GPS) Integrated Navigation System (GINS) with a modern Flight Management System (FMS) that will accommodate new capabilities including Mode 5 IFF and Joint Mission Planning System (JMPS). Also included as part of the modification is the addition of data link communications, voice and data link digital radios, and improved visual displays
Boeing recently completed the first flight of a NATO E-3A Sentry Airborne Warning and Control (AWACS) updated with modernized flight deck and avionics systems, according to a company press release. Testers evaluated five full-color “glass cockpit” displays, each with customizable engine, navigation, and radar data, during the successful two-hour flight flown on the last day of 2014.
The E-3 AWACS is considered the most capable airborne surveillance system in the world. It was designed to meet specific goals and has been optimized to perform its task extremely well. However, advances in technology have made further radar improvements possible. Future modifications will allow AWACS to adapt to evolving missions and threats.
- Detection and tracking of an expanded variety of target types, including slow or maneuvering targets, helicopters, and high speed targets such as missiles
- Improved detection performance and better track quality through processing techniques
- Greater frequency flexibility to operate effectively in the presence of electromagnetic interference
- Improved user interface
- Improved system reliability, maintainability, and availability (RMA)
In addition to its original AEW missions, AWACS is essential to a broad variety of operations, including Peace Support Operations, multi-national coalitions, air control, Homeland Defense, counter-narcotics, Combat Search and Rescue, and more.
In 2005, a major upgrade of the UK Royal Air Force’s Boeing E-3D Sentry fleet, dubbed Project Eagle was launched. Its aim was to transform the airborne radar aircraft into the hub of the UK’s network-centric warfare capability. At the heart of the upgrade, potentially costing $500 million, is the incorporation of the US Network-Centric Collaborative Targeting (NCCT) technology, which compresses the sensor-to-shooter loop by allowing a much wider range of information on ground targets to be inserted into the displays currently used by E-3D crew members to monitor air activity.
Radar System Improvement Program (RSIP)
In order to counter today’s increasing threat sophistication, the AWACS radar has been significantly upgraded under the Radar System Improvement Program (RSIP). The RSIP modifications enhance radar performance characteristics, add new capabilities, improve the user interface, and lower the life-cycle cost of the AWACS radar, while improving reliability.The program provides increased air defense and command and control through significant improvements in: radar sensitivity and electronic counter-counter measures performance; radar performance monitoring and control; and reliability and maintainability.
The improvement in detection performance is accompanied by impressive improvements in range and angular resolution. Range resolution is increased by up to 6 to 1, and azimuth and elevation accuracy by up to 2 to 1.RSIP introduces advanced pulse Doppler waveforms, pulse compression, and new processing algorithms implemented by hardware and software improvements that allow the system to detect and track targets at up to twice the range of the original AWACS.
The radar’s ability to respond to electronic attack is significantly improved as well. This improvement is the result of incorporating the latest technology in clutter rejection, processing, and man machine interface (MMI). RSIP provides multiple radar modes to allow for operational flexibility. Some of these modes are:
- Multi-mode Radar: Flexibility to Watch the Skies
- Pulse Doppler Non Elevation Scan (PDNES): The PDNES mode provides surveillance of aircraft down to the surface by using pulse Doppler radar, with Doppler filters and a sharply defined antenna beam.
- Pulse Doppler Elevation Scan (PDES): Radar operation in the PDES mode is similar to PDNES, but target elevation is derived by an electronic vertical scan of the beam.
- Beyond-the-Horizon (BTH): The BTH mode uses pulse radar – without Doppler – for extended range surveillance where ground clutter is in the horizon shadow.
- Maritime: A very short pulse is used to decrease the sea clutter patch for detection of large and small surface ships in various sea states. An adaptive digital processor automatically adjusts to variations in sea clutter and blanks land returns by means of stored maps of land areas
- Interleaved: PDES and BTH can be used simultaneously with either portion active or passive. PDNES can be used simultaneously with maritime.
- Passive: The radar transmitter can be shut down in selected subsectors while the receivers continue to receive and process data. This is an effective feature in a jammed (ECM) environment. A single accurate line (strobe) passing through the location of each jammer is generated on the display console.