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Naval signal boxes.

Despite its combat debut during the Second World War, the radar is still a relatively young technology. However, in almost seven decades, it has revolutionised naval warfare, providing an ability to see far beyond a ship's horizon, and a means by which missiles can be directed against maritime and land targets. It is, therefore, no surprise that defence contractors throughout the world have worked to design signals intelligence (or sigint as it now has become known) systems for detecting and identifying hostile radars. In some cases, these sigint systems can activate a collocated electronic countermeasure to jam the radar.

The rationale is to prevent the hostile radar from seeing one's vessel from long range, thus denying it a possible firing solution for an anti-ship missile. Should such a missile be launched, naval sigint equipment has an important role to play, particularly if these missiles are radar-guided, such as the MBDA MM40 Exocet, as the same equipment can be used to identify and classify the missile's radar. The targeted vessel can then take the appropriate action by launching countermeasures and taking defensive manoeuvring.

Furthermore, the ability to identify and track multiple threats is important for naval signals intelligence. Any missile attack on a ship using radar-guided weapons is unlikely to comprise a single round. Instead several weapons will probably be launched to saturate defences and ensure multiple hits. Thus the ability to track multiple radar threats, and initiate electronic countermeasures, becomes a matter of survival.

Pearls of Wisdom

The marketplace for naval self-defence sensors is a crowded one, with several products available to all naval combatants. For example, Rafael of Israel has developed the C-Pearl electronic support measure family to detect and classify hostile radar emissions. This system has been sold to the Israeli Sea Corps and the Royal Australian Navy to equip the latter's Adelaide class frigates. The company notes that one of the attractions of the C-Pearl is that it can be used by vessels of all sizes, from small patrol craft to aircraft carriers.

Joining Rafael, Israel Aerospace Industries' Elta, which produces the EL-8382N 3D. Elta has leveraged technology that it developed for a land-based radar detection system into this sea-based derivative. Like all of the systems surveyed in this article, the EL-8382N includes a threat library of radar emissions that is included in the equipment's mission planning system. New radar signals can be stored in a separate memory to be analysed at a later date, for example when the vessel is back in port. Once analysed, these signals can be loaded into the threat library, allowing the same signals to be monitored in the future as a possible threat. The EL-8382N also comes loaded with a simulation system allowing the operator to be trained in signal analysis using computer-generated scenarios, either when the ship is underway or portside.

Israel's other major electronic systems provider, Elbit, is thought to have sold its Timnex 4 electronic intelligence system to equip some of China's submarines, along with other unidentified surface combatants, and Israel's Dolphin class diesel electric boats. The Timnex 4 covers a frequency range of 2 to 18 GHz. This encompasses S-band, C-band, X-band, and Ku-band radar such as BAE Systems' Sampson (S-band), EADS TRS-3D (C-band) and Terma's Scanter-6000 (X-band). An option is offered to extend coverage to 0.5 to 40 GHz to cover one to two-GHz L-band systems such as the BAE Systems Type-1022 radar as well as systems covering the K-band (18 to 27 GHz) and Ka-band (27 to 40 GHz). In terms of performance, the Timnex 4 can track up to 256 emitters in real time. Elbit has also configured the product to work in a dense electromagnetic environment.

Born in the USA

Meanwhile, ITT has the responsibility for a number of naval electronic self-protection systems. These include the ES-3701, which can detect radar emissions between 2 and 18 GHz, and can be programmed to monitor specific predefined hostile signals, alerting the crew upon detection. The system comprises a pair of omni-directional aerials and direction-finding sensors that cover the two to six-GHz and 6 to 18-GHz frequencies, along with a GPS antenna. The ES-3701 is used on the Hellenic Navy's Elli class frigates and on the Absalon class flexible support ships of the Kongelige Danske Marine (Royal Danish Navy).

Supplementing the ES-3701, ITT also builds the ES-3601 tactical radar electronic support measure and surveillance system, providing a 2 to 18 GHz frequency range coverage over 360[degrees], with the option to extend to wideband coverage between 1 and 40 GHz. The ES-3601 boasts a reaction time of less than one second and can track up to 500 emissions simultaneously, with a library large enough to store over 10,000 emitter records. The company notes that, as well as equipping surface vessels, the ES-3601 makes an ideal fit for submarines and even for land application and uses a Windows-based man-machine interface, with option of a Unix-based system if preferred by the customer. In order to ease training, ITT has added a built-in synthetic simulator allowing prospective ES-3601 operators to be trained directly on the equipment.

ITT's ES-5080 set, of which 55 are on order, is on the other hand particularly well suited for the detection of low-probability-of-intercept radar. Its man-machine interface also uses a Windows-based architecture and can be used as a stand-alone system, or is integrated into a ship's combat management system.

The ES-5060 Electronic Support Measure/Electronic Intelligence system, also from ITT, can listen for radar signals across 0.5 to 18 GHz, although it has the option to be increased to 40 GHz in order to cover the K-band and Ka-bands. Once the CS-5080 has detected a radar emission, its integral SP-103 classification system will measure the emission's frequency, azimuth and amplitude. This will provide the crew with an idea of the type of radar painting their vessel and whether this radar is friendly. The SP-103 achieves this by comparing the emission with a library of radar characteristics. Should that radar be classified as hostile, the crew can then decide what sort of countermeasure to deploy or which evasive action should be taken.

Beneath the waves, one can find ITT's electronic intelligence equipment on a number of submarines. The AR-900 covers the 2 to 18 GHz segment of the spectrum and comprises an antenna array, processing unit and workstation. In total, the AR-900 can monitor up to 500 signals and has a library that can hold over 10,000 radar threat records. For customers requiring extensions to the L and K/Ka-bands, the AR-900 can undergo an optional frequency extension. Vessels outfitted with the AR-900 include the Armada de Chile (Chilean Navy's) Scorpene class diesel electric submarines.

As with the CS-5080, Raytheon's AN/SLQ-32(V) electronic support measure can be linked to a ship's combat management and electronic countermeasures systems. This has been optimised to detect ship-based surveillance radar and radar emissions from anti-ship missiles. Development of the AN/SLQ-32(V) ostensibly began in the early 1970s, reportedly resulting from concerns regarding Soviet anti-ship missile development. In 1967, during the Six Day War, the Israeli Sea Corps' Eilat destroyer was sunk by an MKB Raduga Design Bureau P-15 Termit (or SS-N-2 Styx in Nato parlance) radar-guided anti-ship missile.

The AN/SLQ-32(V), which provides threat direction finding, early warning and target identification for multiple threats, has been produced in several variants over the years. These have included the AN/SLQ-32(V)2, which added improvements to the system's abilities to perform accurate direction finding for radar-guided anti-ship missiles. The third version, the AN/SLQ-32(V)3, had an integral jamming capability for missile radar, while a forth variant, the AN/SLQ-32(V)4 was specifically configured for aircraft carriers. Customising the AN/SLQ-32(V) for specific vessels has continued with the AN/SLQ-32(V)5 being designed to equip the US Navy's Oliver Hazard Perry class frigates.

Several other American companies are providing electronic intelligence sensors for naval vessels. They include Lockheed Martin, which has designed the AN/ALQ-210, scheduled to equip the US Navy's new Sikorsky MH-60R naval helicopters. Outfitting the MH-60R with the AN/ALQ-210 allows a ship to extend its organic sensor range well over the horizon. Like ITT's CS-5080, the AN/ALQ-210 has been designed with a library that can be updated with details of new radar emissions as and when they are discovered.

As well as flying its systems on helicopters, Lockheed Martin has developed electronic support measures for surface ships. These include the company's AN/ALQ-501 Canadian Electronic Warfare System. Its name derives from its selection to outfit the Canadian Halifax class frigates and Iroquois class destroyers. The AN/ALQ-501 is designed to detect L-, C-, S- and X-band ship-based radar and missile emissions and, as now is the norm, features an updateable threat library.

Also part of Lockheed Martin's naval sigint catalogue is the company's AN/BLQ-10(V). This electronic support measure kit was designed to provide both the Los Angeles and Virginia class nuclear-powered attack submarines of the US Navy with a new radar and communication intelligence system. Here, Lockheed Martin has made a widespread use of commercial off-the-shelf technology and non-development items, reaching a proportion of over 90% in hardware and software.

As with many submarine subsystems, details regarding the exact capabilities of this product are sketchy. However, it is thought that the AN/BLQ-10 includes a wideband receiver plus two narrowband radar receivers, both sensors of which are installed on a modular mast. The installation of this equipment will allow these boats to not only detect radar signals, but also HF, VHF and UHF communication traffic, in addition to communication across cell phone networks. The latter capability will be very useful for these submarines when they are performing intelligence gathering in the littoral area. The full installation of the AN/BLQ-10 across both submarine classes is expected by 2012.

The US Navy is now planning the eventual replacement of the AN/SLQ-32(V) seen above as part of its Surface Electronic Warfare Improvement programme. General Dynamics has teamed with BAE Systems to fulfil the Block 2 segment of this requirement. The solution is based on the Sea Lightning surface electronic warfare system. Using open architecture and technology developed by BAE Systems for its Barracuda naval electronic warfare suite, the Sea Lightning will provide radar and missile threat information.

European Systems

BAE System's Passive Radar Identification System (better known as the Prism) has been optimised for smaller-sized vessels and to this end the Prism II was selected in 1994 to equip the Fremantle class offshore patrol craft and Hunt class (the Prism III for the latter) mine warfare ships belonging to the Australian Navy. Like many of the systems discussed in this article, the Prism II can be connected to a ship's electronic countermeasures and combat management systems to provide radar classification and information regarding the hostile emitter's location. Primarily, the Prism series is designed to detect radar emissions in the 2 to 18 GHz range.

Across the Channel Thales has developed electronic support measures optimised for medium and large surface combatants. The company is now responsible for the Sabre, which was developed by Racal in the late 1990s. The Sabre can automatically trigger a response from a vessel's electronic countermeasures, as well as detecting, analysing and classifying the radar threat. The Sabre comprises a mast-mounted electronic support measure antenna, which includes a microwave receiver to detect radar emissions, details of which are then fed to analytical equipment, which then performs the pulse measurement and direction-finding tasks.

The Sabre was sold to the Koninklijke Marine (Royal Dutch Navy) for installation on the De Zeven Provincien class frigates and has also been procured by the Marine Nationale (French Navy). The Sabre covers the 0.5 to 18 GHz frequency range allowing it to detect threats in the lower reaches of the L-band.

Indeed the range of naval electronic support measures produced by Thales is impressive to say the least. The company's DR3000S has been installed on the Barzan fast attack craft operated by the Royal Qatari Navy where it operates alongside the company's Salamandre ARBB-33 radar jammer. Meanwhile, modularity is the watchword for Thales's Vigile family of electronic support measures. The Vigile listens to radar emitting between 2 and 18 GHz (with an optional extension of 0.5 to 40 GHz) and can detect single pulses as well as perform accurate direction finding and, using its digital receiver, can detect low-probability-of-intercept radar. It has been installed on Oman's Khareef ships as well as on Morocco's and Indonesia's Sigma corvettes.

Although Thales dominates the European naval electronic support measures market, other suppliers manufacture similar products. Indra of Spain, for example, has developed the electronic intelligence gathering BLQ-355 used on the country's Galerna class hunter-killer submarines. The BLQ-355 has a so-called 'pop-up' design feature that allows the equipment to be momentarily activated to ascertain if the boat is being painted by hostile radar, before shutting down to avoid detection by hostile electronic counter-countermeasures. In total, the threat library for the BLQ-355 can include up to 3000 emitter modes and 256 different radar signals.

By definition, low-probability-of-intercept radar is of grave concern to the world's navies, particularly when those navies have to operate in today's dense electromagnetic environments. Elettronica of Italy produces the Seal electronic support measures line which is designed to detect exactly these types of threats using both omni-directional and directional aerials to locate the emission and define its frequency. This information is then passed on to the vessel's electronic countermeasures for deception and spoofing.

In Germany, EADS produces naval signals intelligence systems, which include the FL-1800U, outfitting Germany's Type 212 submarines. Comprising four spiral aerials and a radar-warning receiver, the FL-1800U can track radar in the 0.5 to 18 GHz band.

Future Proof?

The continuing development of naval surveillance radar and evolutions in radar-guided anti-ship missiles will ensure that the tireless work of naval signals intelligence sensor designers and engineers will continue. Electronic warfare has always been an exercise in cat-and-mouse development, with every new evolution in radar technology heralding a development in signals intelligence systems, and vice-versa. Looking toward the future, systems like the AN/BLQ-10(V) may be a portent for equipment that not only performs radar transmission intelligence gathering, but also gathers information on communications intelligence.
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Title Annotation:Naval: electronic warfare
Author:Withington, Thomas
Publication:Armada International
Geographic Code:7ISRA
Date:Oct 1, 2010
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