Singapore receives Herakles radar while Thales looks forward to FREMM contract
Thales Naval France has disclosed new technical and program me details of its Herakles naval multifunction radar (M FR).
The system, a surveillance- and fire- control radar-in-one that operates in ElF-band (Sband), has been selected by the French defence procurement agency DGA to equip the proposed FREMM (Fregates Europeennes Multi-Mission) multimission frigates of which the French Navy is planned to receive 17 (procured in a collaborative programme with Italy).
For the French FREMM requirement, the Herakles radar had to defeat competition from Germany (the Janus radar offered by EADS Defence Electronics) and Italy (the Empar offered by AMS). A contract is expected by the end of this year (2005).
Six Herakles systems have already been sold to launching custom er Singapore to be used as the primary above-water sensor on six 3,800-tonne Form idable-class (Project Delta) stealth frigates, which are being built by DCN of France (lead ship) and ST Marine of Singapore (ship 2-6).
The first Herakles was installed at the DCN Lorient shipyard on the first-of-class ship, RSS Formidable, in September 2004. The ship has been in a series of sea trials since October 2004 with the Herakles on board and is due to arrive in Singapore soon. Integration within the ship's overall combat system, particularly the federated combat management system that is developed by Singapore's Defence Science and Technology Agency (DST A), will then take place in-country for an in-service date of 2006-07.
The second Herakles radar has been undergoing an extensive series of live testing since July 2004 at the DGA-operated Centre d'Essais de Landes (CEL), a land-based test site in Biscarosse, southwestern France. T he testing here is now focusing on the technical
qualification of the Herakles radar with the M BOA-produced Aster 15 surf ace-to-air missile system. Live firings with instrumented Aster rounds, f or which the Herakles will provide fire control support, including mid-course guidance uplink, are scheduled for later this year.
Herakles three, four, five and six were seen by lOR in various stages of completion during a visit to the Thales-owned radar integration and test facility at Limours, south of Paris, in April 2005. Of these, the third and fourth radar system were fully up and running on the outside pad for far-field testing, with the third about to be shipped to ST Marine in Singapore for installation on the second-of -class ship, RSS Intrepid. T he fifth Herakles and parts of the sixth system were inside the integration hall. T he antenna unit of at least one of the last two was in an anechoic chamber for near-field testing.
The Herakles radars for FREMM are planned to be delivered between 2007-12, and the first frigate in-service date should be in 2009-10, T hales said. The radar is also being offered to several possible ex port customers, one of which being the Danish patrol frigate program me.
According to the com pany, Herakles is a 3-D M FR designed to be either the sole radar on board a frigate-size vessel of 2,800 tonnes or larger, or to be part of an above-water sensor suite working in concert with a long-range radar (such as the T hales SMART-L) that can provide an extended air surveillance picture beyond 400 km.
The Herakles system itself provides a tactical air picture out to 250 k m and can perform target identification and recognition, as well as third-party target designation f or the benefit of other shooter platforms, Thales said.
Thales has already "fully integrated" the Herakles with MBDA's active radar-homing Aster fam ily of surface-to-air missiles, including amid-course guidance uplink functionality. "The radar is accurate enough to work with the US family of semi-active radar-homing missiles [Raytheon Standard Missile SM-2 and Evolved SeaSparrow Missile ESSM] but for these it would be required to add a separate I/J-band [X-band] target iliumination and mid-course guidance uplink capability," Thales said.
The Herakles radar's passive phased-array antenna unit features a circular front array (produced by Thales Nederland and ref erred to by Thales engineers as the 'lens') equipped with 1,761 phase shifter modules, which can be electronically controlled to steer the radar beams. The 'lens' forms the 'lid' on the forward, wider end of a cone-shaped housing. At the aft, narrower end of this cone is what Thales calls the 'retina' of the radar. This is where the radar energy is fed into the antenna unit and where the returned radar energy is gathered and channelled back into the processing cabinets.
Mounted on the rear of the cone and facing aft is the antenna of the identification friend-or foe (I FF) interrogator system. On the topside is an upwards-f acing zenithal horn to provide radar coverage directly overhead the ship.
The Herakles is basically operated as a multibeam radar for surveillance m odes and as a pencil-beam radar for target tracking -- activities that are happening simultaneously as they are interleaved by the radar's space-time management unit. "To cover a volume out to 250 km and up to 80,000 ft; 360° around; up to an elevation of 70°, every second, there has to be a secret, and the secret is that we use the m ultibeam concept," a Thales engineer said.
Doppler processing is used f or clutter rejection, and the radar is claim ed to be capable of initiating most tracks within one second (the first rotation after detection) -- or, in highly stressful cases such as an incom ing sea- skimming missile, within two seconds (the second rotation after detection).
All targets are tracked with a dedicated track ing waveform rather than using the track-whilescan concept. The radar is claimed to be capable of classifying the target type based on the raw radar return (non-co-operativ e target recognition).
Herakles antenna units for Singapore are placed inside a topless pyramid-shaped radome with four lightning deflector aerials mounted on the four top corners. Protection is provided against both indirect and direct lightning strik es of up to 200 kilo-amps.
The entire radom e, with the antenna unit inside, weighs m ore than 3,000 kg but is rotated once every second (60 rpm) by a specially designed electric-powered, water-cooled, direct drive motor. The motor, for which the main parts are supplied by Etel of Switzerland and of which the assembly and tuning is performed by Thales Nederland, drives two rings, each measuring 1.20 m wide and 15 cm high.
Maintenance is limited as the rotation is facilitated by electromagnetic forces, meaning that there is hardly any friction between the rotor and the stator.
The amplification of the power required to drive the motor is provided by two sets of capacitators located in a cabinet one level below the antenna unit - redundancy is provided as only a single channel is sufficient to rotate the antenna unit. T he antenna's rotation speed is kept constant by automatically adapting the current to the outside wind conditions (the higher the current, the higher the torque).
On the French FREM M frigates, the Herak les antenna unit is to be placed without its dedicated radom e inside an integrated single main mast structure. Inside, the antenna unit will rotate but the mast structure will be fixed, so it will be im possible to tell from the outside if the radar is turning or not.
The ElF-band RF energy for the Herakles is generated by a set of 40 solid-state power modules (known as 'power books'). Weighing 16 kg each and cooled by a mix of water and glycol, these provide significant redundancy and maintenance advantages, Thales said. "The loss of one of the 40 modules, or 1/40th of the power, is negligible in term s of radar performance. Even the loss of 50 per cent of the modules will only lead to a 20 per cent reduction of the radar range performance," an engineer said.
He added: 'The reliability is such that within the usual mission duration of around 45 days, we do not normally expect any of the modules to faiL"
According to Thales, it has chosen the ElF-frequency band for Herakles not only because that is "the least sensitive to clutter in the littoral environment" but also because in ElF-band the solid-state transmitter technology is "easily affordable and highly reliable in term s of stability".
Another cabinet hosts the radar signal generator and high-dy namic reception unit, as well as the missile uplink generator needed to generate signals to be transmitted via the radar to own missiles after these have been launched to intercept incoming targets. The radar signal generator is the same as is used in the Thales-built Master family of land-based 3-D air-defence radars - to the development of which Singapore is believed to have contributed. lOR believes that the southeast Asian city state procured a number of these Master radars during the 1990s, although this has never been officially confirmed.
The signal generator is triggered by a space-time management (STM) device that is described by Thales engineers as governing the "heartbeat" of the radar. "It delivers all the triggers to all the com ponents of the radar, at a rate that is measured in a few milliseconds and looking ahead around 10 milliseconds to what the radar needs to be doing then."
In the signal processing cabinet, f our channels for air targets, one channel for surface targets and one sidelobe blank ing channel are handled by a cluster of 200 processors working in parallel. T he processing per channel can be set at norm al-, intermediate- or high-resolution mode. Thales has chosen to not adopt com mercial off-the-shelf (COTS) processing boards but instead uses its in-house developed Camaro family of processing boards, of which three different types are used in Herakles. "If we would have used COTS products we would have needed three times as many processors, because these are not as integrated as our Camaro technology," an engineer claim ed.
Camaro boards are also used in other T hales radars such as the M RR-3D NG naval radar and STAR radars for air-traffic management.
The final electronics cabinet in the Herakles system houses COTS-based (IBM PowerPC) data-processing activities such as radar management, built-in test equipment control, Aster missile fire-control support and the interface unit to the on-board ship's local area network.
The Herakles radar would normally be operated from consoles in the ship's combat information centre (CIC). However, in the Singapore configuration there is also a dedicated local control workstation that is situated in the vicinity of the radar system.
Thales engineers em phasised that "all maintenance activities to keep the Herakles up and running can be performed from inside the mast structure - there is no need to remove the radome at all except during overhaul". Installation on board a ship is "straightf orward," the engineers claimed, stating that it "only takes 64 bolts to attach the system" and that it required the DCN Lorient shipyard "only half a day" to install the first Herakles system on board the RSS Form idable.
