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.
