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57-518: The Sea-Based X-band radar ( SBX-1 ) is a floating, self-propelled, mobile active electronically scanned array early-warning radar station designed to operate in high winds and heavy seas. It was developed as part of the United States Department of Defense Missile Defense Agency's (MDA) Ballistic Missile Defense System. The radar is mounted on a fifth generation CS-50 twin-hulled semi-submersible oil platform . Conversion of

114-411: A "limited test support" role, "while also retaining the ability to recall it to an active, operational status if and when it is needed." In April 2012, it was reported that SBX-1 had left Pearl Harbor and was assumed to be being deployed to monitor North Korea's planned Unha-3 missile in the launch window of 12–16 April 2012. The vessel returned to Pearl Harbor on 21 May 2012. It redeployed to monitor

171-501: A flight test on 31 January 2010, designated FTG-06. The test was a simulation of a North Korean or Iranian missile launch. The test failure arose from two factors, the first being that algorithms in the SBX radar software (designed to filter out extraneous information from the target scene) were left disengaged for the test, and the second was a mechanical failure in a thruster on the kill vehicle. During flight test FTG-06a on 15 December 2010,

228-626: A hybrid approach, the benefits of AESA (e.g., multiple independent beams) can be realized at a lower cost compared to pure AESA. Bell Labs proposed replacing the Nike Zeus radars with a phased array system in 1960, and was given the go-ahead for development in June 1961. The result was the Zeus Multi-function Array Radar (ZMAR), an early example of an active electronically steered array radar system. ZMAR became MAR when

285-497: A much simpler radar whose primary purpose was to track the outgoing Sprint missiles before they became visible to the potentially distant MAR. These smaller Missile Site Radars (MSR) were passively scanned, forming only a single beam instead of the MAR's multiple beams. While MAR was ultimately successful, the cost of the system was enormous. When the ABM problem became so complex that even

342-441: A much wider range of frequencies, to the point of changing operating frequency with every pulse sent out. Shrinking the entire assembly (the transmitter, receiver and antenna) into a single "transmitter-receiver module" (TRM) about the size of a carton of milk and arraying these elements produces an AESA. The primary advantage of an AESA over a PESA is the capability of the different modules to operate on different frequencies. Unlike

399-420: A narrow range of frequencies to high power levels. To scan a portion of the sky, the radar antenna must be physically moved to point in different directions. Starting in the 1960s new solid-state devices capable of delaying the transmitter signal in a controlled way were introduced. That led to the first practical large-scale passive electronically scanned array (PESA), or simply phased array radar. PESAs took

456-456: A rotating antenna, or similar passive array using phase or amplitude comparison . Typically RWRs store the detected pulses for a short period of time, and compare their broadcast frequency and pulse repetition frequency against a database of known radars. The direction to the source is normally combined with symbology indicating the likely purpose of the radar – airborne early warning and control , surface-to-air missile , etc. This technique

513-406: A second polarization, totaling 44,000 feed horns. The base is roughly 2/3 populated, with space for installation of additional modules. The current modules are concentrated toward the center to minimize grating lobes. This configuration allows it to support the very-long-range target discrimination and tracking that GMD's midcourse segment requires. The radar is never pointed at land, for the safety of

570-451: A signal and then listening for its echo off distant objects. Each of these paths, to and from the target, is subject to the inverse square law of propagation in both the transmitted signal and the signal reflected back. That means that a radar's received energy drops with the fourth power of the distance, which is why radar systems require high powers, often in the megawatt range, to be effective at long range. The radar signal being sent out

627-415: A signal from a single source, split it into hundreds of paths, selectively delayed some of them, and sent them to individual antennas. The radio signals from the separate antennas overlapped in space, and the interference patterns between the individual signals were controlled to reinforce the signal in certain directions, and mute it in all others. The delays could be easily controlled electronically, allowing

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684-636: A single frequency at a time. The PESA must utilize a Butler matrix if multiple beams are required. The AESA can radiate multiple beams of radio waves at multiple frequencies simultaneously. AESA radars can spread their signal emissions across a wider range of frequencies, which makes them more difficult to detect over background noise , allowing ships and aircraft to radiate powerful radar signals while still remaining stealthy, as well as being more resistant to jamming. Hybrids of AESA and PESA can also be found, consisting of subarrays that individually resemble PESAs, where each subarray has its own RF front end . Using

741-636: A system like MAR could no longer deal with realistic attack scenarios, the Nike-X concept was abandoned in favor of much simpler concepts like the Sentinel program , which did not use MAR. A second example, MAR-II, was abandoned in-place on Kwajalein Atoll . The first Soviet APAR, the 5N65 , was developed in 1963–1965 as a part of the S-225 ABM system. After some modifications in the system concept in 1967 it

798-419: A wide band even in a single pulse, a technique known as a "chirp". In this case, the jamming will be the same frequency as the radar for only a short period, while the rest of the radar pulse is unjammed. AESAs can also be switched to a receive-only mode, and use these powerful jamming signals to track its source, something that required a separate receiver in older platforms. By integrating received signals from

855-460: A wider angle of total coverage. This high off-nose pointing allows the AESA equipped fighter to employ a crossing the T maneuver, often referred to as "beaming" in the context of air-to-air combat, against a mechanically scanned radar that would filter out the low closing speed of the perpendicular flight as ground clutter while the AESA swivels 40 degrees towards the target in order to keep it within

912-411: Is a simple radio signal, and can be received with a simple radio receiver . Military aircraft and ships have defensive receivers, called " radar warning receivers " (RWR), which detect when an enemy radar beam is on them, thus revealing the position of the enemy. Unlike the radar unit, which must send the pulse out and then receive its reflection, the target's receiver does not need the reflection and thus

969-417: Is common on ships, for instance. Unlike the radar, which knows which direction it is sending its signal, the receiver simply gets a pulse of energy and has to interpret it. Since the radio spectrum is filled with noise, the receiver's signal is integrated over a short period of time, making periodic sources like a radar add up and stand out over the random background. The rough direction can be calculated using

1026-625: Is derived from the radar used in the THAAD theater ballistic missile defense system , and is a part of the layered ballistic missile defense system (BMDS) program of the United States Missile Defense Agency (MDA). One important difference from Aegis is the use of X band in the SBX. Aegis uses S band , and Patriot uses the higher-frequency C band . The X band frequency is higher still, so its shorter wavelength enables finer resolution of tracked objects. The radar

1083-454: Is much less useful against a radar with a frequency-agile (solid state) transmitter. Since the AESA (or PESA) can change its frequency with every pulse (except when using doppler filtering), and generally does so using a random sequence, integrating over time does not help pull the signal out of the background noise. Moreover, a radar may be designed to extend the duration of the pulse and lower its peak power. An AESA or modern PESA will often have

1140-448: Is not - the flexible cover is supported by positive air pressure amounting to a few inches of water. The amount of air pressure is variable depending on weather conditions. The radar antenna itself is described as being 384 m (4,130 sq ft). It has 45,000 solid-state transmit-receive modules mounted on an octagonal flat base which can move ±270 degrees in azimuth and 0 to 85 degrees elevation (although software currently limits

1197-434: Is then disconnected and the antenna is connected to a sensitive receiver which amplifies any echos from target objects. By measuring the time it takes for the signal to return, the radar receiver can determine the distance to the object. The receiver then sends the resulting output to a display of some sort . The transmitter elements were typically klystron tubes or magnetrons , which are suitable for amplifying or generating

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1254-412: Is used as the setting for the 2022 action drama film Interceptor . The SBX-1 has become known to locals of Oahu as the " Golf Ball " or the "Pearl of Pearl Harbor" due to its color and shape. Active electronically scanned array The AESA is a more advanced, sophisticated, second-generation of the original PESA phased array technology. PESAs can only emit a single beam of radio waves at

1311-442: Is used. Target motion analysis can estimate these quantities by incorporating many directional measurements over time, along with knowledge of the position of the receiver and constraints on the possible motion of the target. Since each element in an AESA is a powerful radio receiver, active arrays have many roles besides traditional radar. One use is to dedicate several of the elements to reception of common radar signals, eliminating

1368-406: Is why AESAs are also known as low probability of intercept radars . Modern RWRs must be made highly sensitive (small angles and bandwidths for individual antennas, low transmission loss and noise) and add successive pulses through time-frequency processing to achieve useful detection rates. Jamming is likewise much more difficult against an AESA. Traditionally, jammers have operated by determining

1425-740: The IMO number of 8765412. The first such vessel is scheduled to be based in Adak Island , Alaska , part of the Aleutian Islands . From that location it will be able to track missiles launched toward the US from both North Korea and China . Although her homeport is in Alaska, she will be tasked with moving throughout the Pacific Ocean to support her mission. The hull code number given to

1482-492: The 'building blocks' of an AESA radar. The requisite electronics technology was developed in-house via Department of Defense research programs such as MMIC Program. In 2016 the Congress funded a military industry competition to produce new radars for two dozen National Guard fighter aircraft. Radar systems generally work by connecting an antenna to a powerful radio transmitter to emit a short pulse of signal. The transmitter

1539-444: The 1960s, followed by airborne sensors as the electronics shrank. AESAs are the result of further developments in solid-state electronics. In earlier systems the transmitted signal was originally created in a klystron or traveling wave tube or similar device, which are relatively large. Receiver electronics were also large due to the high frequencies that they worked with. The introduction of gallium arsenide microelectronics through

1596-448: The 1980s served to greatly reduce the size of the receiver elements until effective ones could be built at sizes similar to those of handheld radios, only a few cubic centimeters in volume. The introduction of JFETs and MESFETs did the same to the transmitter side of the systems as well. It gave rise to amplifier-transmitters with a low-power solid-state waveform generator feeding an amplifier, allowing any radar so equipped to transmit on

1653-465: The AESA system of a Raptor to act like a WiFi access point, able to transmit data at 548 megabits per second and receive at gigabit speed; this is far faster than the Link 16 system used by US and allied aircraft, which transfers data at just over 1 Mbit/s. To achieve these high data rates requires a highly directional antenna which AESA provides but which precludes reception by other units not within

1710-517: The AESA's 60 degree off-angle limit. With a half wavelength distance between the elements, the maximum beam angle is approximately ± 45 {\displaystyle \pm 45} °. With a shorter element distance, the highest field of view (FOV) for a flat phased array antenna is currently 120° ( ± 60 {\displaystyle \pm 60} °), although this can be combined with mechanical steering as noted above. The first AESA radar employed on an operational warship

1767-498: The PESA, where the signal is generated at single frequencies by a small number of transmitters, in the AESA each module generates and radiates its own independent signal. This allows the AESA to produce numerous simultaneous "sub-beams" that it can recognize due to different frequencies, and actively track a much larger number of targets. AESAs can also produce beams that consist of many different frequencies at once, using post-processing of

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1824-557: The SBX has been on operational deployments in the Pacific, including the waters off Alaska. The ship has not moored at Alaska, in spite of the construction of a $ 26 million, eight-point mooring chain system installed in 2007 in Adak 's Kuluk Bay . On 23 June 2009, the SBX was moved to offshore Hawaii in response to a potential North Korean missile launch. Between 2009 and 2010, the vessel spent 396 continuous days at sea. The SBX failed during

1881-647: The SBX performed as expected, but intercept of the target missile was again not achieved. In May 2011, the SBX-1 entered Vigor Shipyard (formerly the Todd Pacific Shipyard) in Seattle for a $ 27 million upgrade and maintenance work by contractor Boeing. The work was completed in about three months and in August 2011, SBX-1 departed Seattle for deployment. In December 2011, MDA transferred responsibility for

1938-541: The SBX project manager for MDA, said that the "SBX is the only one of its kind and there are no current plans for another one". In July 2011, a Missile Defense Agency spokesman explained that other, smaller radars in the Pacific will "pick up the slack" while SBX is in port with its radar turned off. The SBX deployed in 2006. The ship has spent time for maintenance and repair at Pearl Harbor, Hawaii several times, including 170 days in 2006, 63 days in 2007, 63 days in 2008, 177 days in 2009, and 51 days in 2010. When not at Hawaii,

1995-540: The SBX vessel management and physical security to the U.S. Navy's Military Sealift Command . MDA retains responsibility for communications, the X-band Radar, and for mission integration. In February 2012, the Missile Defense Agency requested only $ 9.7 million per year for Fiscal Years 2013 through 2017, down from $ 176.8 million in fiscal 2012. This reduced amount would be used to maintain SBX in

2052-716: The SBX vessel, "SBX-1", indicates the possibility of further units of the class. In circumstances when a vessel is required to be continually on duty over a long period of time, common naval practice is to have at least three units of the type available to allow for replenishment, repair and overhaul. Three further vessels of the CS-50/Moss Sirius design were under construction or contract at the Severodvinsk Shipyard in Russia as of early 2007, but were configured for oil production. On 11 May 2011, Col. Mark Arn,

2109-523: The Zeus program ended in favor of the Nike-X system in 1963. The MAR (Multi-function Array Radar) was made of a large number of small antennas, each one connected to a separate computer-controlled transmitter or receiver. Using a variety of beamforming and signal processing steps, a single MAR was able to perform long-distance detection, track generation, discrimination of warheads from decoys, and tracking of

2166-454: The antennas beamwidth, whereas like most Wi-Fi designs, Link-16 transmits its signal omni-directionally to ensure all units within range can receive the data. AESAs are also much more reliable than either PESAs or older designs. Since each module operates independently of the others, single failures have little effect on the operation of the system as a whole. Additionally, the modules individually operate at low powers, perhaps 40 to 60 watts, so

2223-496: The beam to be steered very quickly without moving the antenna. A PESA can scan a volume of space much quicker than a traditional mechanical system. Additionally, thanks to progress in electronics, PESAs added the ability to produce several active beams, allowing them to continue scanning the sky while at the same time focusing smaller beams on certain targets for tracking or guiding semi-active radar homing missiles. PESAs quickly became widespread on ships and large fixed emplacements in

2280-429: The capability to alter these parameters during operation. This makes no difference to the total energy reflected by the target but makes the detection of the pulse by an RWR system less likely. Nor does the AESA have any sort of fixed pulse repetition frequency, which can also be varied and thus hide any periodic brightening across the entire spectrum. Older generation RWRs are essentially useless against AESA radars, which

2337-657: The combined signal from a number of TRMs to re-create a display as if there was a single powerful beam being sent. However, this means that the noise present in each frequency is also received and added. AESAs add many capabilities of their own to those of the PESAs. Among these are: the ability to form multiple beams simultaneously, to use groups of TRMs for different roles concurrently, like radar detection, and, more importantly, their multiple simultaneous beams and scanning frequencies create difficulties for traditional, correlation-type radar detectors. Radar systems work by sending out

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2394-413: The identified warheads. Testing has raised doubts about the system's ability to perform these tasks, to deal with multiple targets, and to report accurately to command authorities. The vessel has many small radomes for various communications tasks and a large central dome that encloses a phased-array , 1,800 tonne (4,000,000 pound) X band radar antenna. The small radomes are rigid, but the central dome

2451-441: The inhabitants. In addition to the power consumed by the radar, the thrusters which propel the vessel are electric and require substantial power. The maximum speed is approximately 8 knots (9.2 mph; 15 km/h). To support this and all other electrical equipment, the vessel currently has six 3.6-megawatt generators (12-cylinder Caterpillar diesels). The generators are in two compartments, one port and one starboard. The radar

2508-408: The maximum physical elevation to 80 degrees). The maximum azimuth and elevation velocities are approximately 5-8 degrees per second. In addition to the physical motion of the base, the beam can be electronically steered off bore-sight (details classified). There are currently 22,000 modules installed on the base. Each module has one transmit-receive feed horn and one auxiliary receive feed horn for

2565-562: The need for a large high-voltage power supply is eliminated. Replacing a mechanically scanned array with a fixed AESA mount (such as on the Boeing F/A-18E/F Super Hornet ) can help reduce an aircraft's overall radar cross-section (RCS), but some designs (such as the Eurofighter Typhoon and Gripen NG ) forgo this advantage in order to combine mechanical scanning with electronic scanning and provide

2622-464: The need for a separate radar warning receiver. The same basic concept can be used to provide traditional radio support, and with some elements also broadcasting, form a very high bandwidth data link . The F-35 uses this mechanism to send sensor data between aircraft in order to provide a synthetic picture of higher resolution and range than any one radar could generate. In 2007, tests by Northrop Grumman , Lockheed Martin, and L-3 Communications enabled

2679-404: The next North Korean launch attempt at the end of 2012. In April 2013, it was reported that SBX-1 was being deployed to monitor North Korea. It has never been deployed to Adak. In November 2015, it was moved to Pearl Harbor for repairs and testing. It departed Pearl Harbor November 2017 for North Pacific Ocean waters to monitor North Korea ballistic missile operations. In January 2017 the SBX-1

2736-433: The one to be used to jam. Most radars using modern electronics are capable of changing their operating frequency with every pulse. This can make jamming less effective; although it is possible to send out broadband white noise to conduct barrage jamming against all the possible frequencies, this reduces the amount of jammer energy in any one frequency. An AESA has the additional capability of spreading its frequencies across

2793-472: The operating frequency of the radar and then broadcasting a signal on it to confuse the receiver as to which is the "real" pulse and which is the jammer's. This technique works as long as the radar system cannot easily change its operating frequency. When the transmitters were based on klystron tubes this was generally true, and radars, especially airborne ones, had only a few frequencies to choose among. A jammer could listen to those possible frequencies and select

2850-472: The outbound interceptor missiles. MAR allowed the entire battle over a wide space to be controlled from a single site. Each MAR, and its associated battle center, would process tracks for hundreds of targets. The system would then select the most appropriate battery for each one, and hand off particular targets for them to attack. One battery would normally be associated with the MAR, while others would be distributed around it. Remote batteries were equipped with

2907-477: The signal drops off only as the square of distance. This means that the receiver is always at an advantage [neglecting disparity in antenna size] over the radar in terms of range - it will always be able to detect the signal long before the radar can see the target's echo. Since the position of the radar is extremely useful information in an attack on that platform, this means that radars generally must be turned off for lengthy periods if they are subject to attack; this

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2964-487: The system on a mobile sea-based platform was intended to allow the vessel to be moved to areas where it is needed for enhanced missile defense. Fixed radars provide coverage for a very limited area due to the curvature of the Earth . Even though the same limitation applies to the SBX, its ability to move mitigates this limitation. SBX's primary task is discrimination of enemy warheads from decoys, followed by precision tracking of

3021-530: The targets' own radar along with a lower rate of data from its own broadcasts, a detection system with a precise RWR like an AESA can generate more data with less energy. Some receive beamforming-capable systems, usually ground-based, may even discard a transmitter entirely. However, using a single receiving antenna only gives a direction. Obtaining a range and a target vector requires at least two physically separate passive devices for triangulation to provide instantaneous determinations, unless phase interferometry

3078-860: The vessel was carried out at the AmFELS yard in Brownsville, Texas ; the radar mount was built and mounted on the vessel at the Kiewit yard in Ingleside, Texas . It is nominally based at Adak Island in Alaska , but has spent significant time at Pearl Harbor in test status. SBX-1 is part of the Ground-Based Midcourse Defense (GMD) system under development by the Missile Defense Agency (MDA). The decision to place

3135-583: Was built at Sary Shagan Test Range in 1970–1971 and nicknamed Flat Twin in the West. Four years later another radar of this design was built on Kura Test Range , while the S-225 system was never commissioned. US based manufacturers of the AESA radars used in the F-22 and Super Hornet include Northrop Grumman and Raytheon. These companies also design, develop and manufacture the transmit/receive modules which comprise

3192-577: Was deployed into the Pacific during North Korean threats of ICBM and nuclear attacks on other nations. The radar was able to perform its mission of tracking a target operating at ICBM speeds during the interception of a mock ICBM by a GMD interceptor on 30 May 2017. In May 2019, the SBX-1 docked on the north side of Ford Island in Pearl Harbor, where it underwent maintenance. It departed Pearl Harbor on 26 September 2019. A fictionalized version of SBX-1, armed with "Interceptor" anti-ballistic missiles ,

3249-527: Was described by Lt. Gen Trey Obering (former director of MDA) as being able to track an object the size of a baseball over San Francisco in California from Chesapeake Bay in Virginia, approximately 2,900 miles (4,700 km) away. The radar will guide land-based missiles from Alaska and California , as well as in-theater assets, depending on the mission. The vessel is classed by ABS and has

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