http://www.defense-update.com/events/2008/summary/singapore08_nad.htm

In May 2007 Singapore officially confirmed its intention to buy
four Gulfstream G550 special mission business jets, configured for
Airborne Early Warning missions. These aircraft will replace four
Northrop Grumman E-2C Hawkeye aircraft currently in service. The
first aircraft is scheduled for delivery this year According to the
Singapore MOD, the G550 AEW will be capable of flying 9 hours
missions at an altitude of 41,000ft (12,500m). With a longer range
and higher ceiling (up to 51,000 ft), compared to the Hawkeye, the
G550 AEW will provide long-range detection of low-flying targets
and better support long range strike fighters such as the new
F-15SG.
Singapore will receive the first aircraft of this year, and all
four are expected to be operational by 2010. No details were
released about the electronic and radar suite to be installed in
the aircraft, but, it is a known fact that the only system
currently available for this platform is the Israeli IAI/Elta 2085
PHALCON radar, developed for four Israel Air Force G550 AEW
aircraft known as Eitam, currently being delivered by IAI/Elta. The
first aircraft was handed over by Gulfstream on September 2006.
The PHALCON suite includes four sensors - radar, friend or for
identification system (IFF), Electronic Support Measures electronic
intelligence (ESM/ELINT) and Communications Signal Monitoring /
Communications Intelligence (CSM/COMINT) systems. All sensors are
fed through a unique fusion technique, providing continuous
cross-correlation of targets generated by all sensors, providing
automated system-wide tracks of targets detected by each sensor.
The multi-beam, electronically scanning phased array radar utilizes
time-space energy management technique facilitating effective,
multi-mode operations and coverage of 360 degrees using only four
planar sections - two in conformal arrays, and two at the nose cone
and tail sections.
Derivatives of this radar system are operational with the
Chilean Air Force and are under final integration on IL-76 aircraft
for the Indian Air Force. Israel Aerospace Industries developed the
G550 AEW system as part of a broad range of special mission
aircraft, based on Gulfstream's jets. One of these is a SIGNT
platform, developed by IAI's subsidiary Elta Systems, for the
Israel Air Force. For these applications Elta is offering the
EL/I-3001 AISIS – Airborne Integrated SIGINT multi-role Airborne
Integrated Signal Intelligence System (AISIS). The system is
designed to monitor electromagnetic signals (mostly radars) and
communication network environments from long-range, creating an
'electronic order of battle' picture of all relevant threats,
providing up-to-date tactical and strategic intelligence feeding
the nation's intelligence database. AISIS can search, intercept,
measure, locate, analyze, classify and monitor many types of
ground, airborne and naval transmissions, characterized by short
duration, variety of signal types and frequent changes in signals
parameters.
A different special mission aircraft of the Gulfstream 5
platform is IAI's MARS² - a multi-role airborne system designed to
operate as a fast-deployment, all-in-one task force. MARS² enhances
the situational picture available to theater commanders, with real
time radar, imagery, electronic intelligence sensors linked
on-board with command, control and communication (C3) functions
creating intelligence and situational picture for effective battle
command of special mission.
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