The Bradley fighting vehicle, which transports U.S. Army infantry
and cavalry troops, operates alongside the Abrams main battle tank
and provides the firepower to support dismounted soldiers or attack
enemy armor and fortifications.
The Army has been working for several years to improve the Bradley
in a series of upgrade programs. The most modern versions of the
Bradley are the M2A3 infantry and M3A3 cavalry fighting vehicles.
Among the capability enhancements found in both the M2A3 and M3A3
vehicles is the "improved Bradley acquisition subsystem,"
or IBAS.
The 2nd Infantry Battalion, 8th Infantry Regiment of the 4th Mechanized
Infantry Division, at Fort Hood, Texas, became the first unit equipped
with the modernized M2A3 Bradley in May.
IBAS uses second-generation forward-looking infrared (Gen II FLIR)
technology to help the Bradley crew acquire and identify targets
in night or day. Under the Army's horizontal technology integration
(HTI) initiative, IBAS shares its Gen II FLIR with other platforms.
The Army plans to modernize about 1,100 Bradleys with IBAS, a commander's
independent viewer (CIV), and Force XXI digital command and control
improvements, including a MIL-STD-1553 databus. DRS Technologies,
based in Parsippany, N.J., received a low-rate, initial-production
contract in January 2000, for the IBAS subsystems. A decision to
transition IBAS to full production in 2001, is expected later this
year.
The Gen II FLIR sensor of the new Bradley sight is packaged in
a B-kit, a working sensor, which is also common to the commander's
independent thermal viewer on the M1A2 Abrams tank and the long-range
advanced scout surveillance system (LRAS3) on the M1025 scout vehicle.
The same B-kit is a candidate to upgrade the Marine Corps' Abrams
tanks and other ground vehicles worldwide.
Seeing Through a Storm
With its second-generation thermal imager, IBAS addresses the shortcomings
of the first-generation common module FLIRs used on the M2A2 Bradley
in Operation Desert Storm. The original Bradley TOW 2 subsystem
(T2SS) has both a thermal imaging FLIR and direct view optics to
aim the TOW 2 (tube launched, optically tracked, wire guided) missile
and the 25mm cannon.
While the first-generation thermal imager sees in the dark, it
has an effective range which is less than the maximum stand-off
range of the missile. The range of the first-generation sight is
cut even more in dense fog, dust or other battlefield obscurants.
The shorter-range targeting sensor puts the Bradley at greater
risk by forcing the vehicle closer to the enemy for target acquisition,
identification and recognition. Even under ideal conditions, the
lack of detail in first-generation FLIR imagery makes it difficult
to distinguish friends from enemies. Command and control is difficult
to optimize without the ability to pass digital information and
imagery between units.
The Army sought the M2A3 Bradley upgrade after assessing the threats
expected for the 21st century battlefield. IBAS integrates Gen II
FLIR with daylight television, direct view optics and an improved
TOW missile control subsystem. It provides the modernized Bradley
with a more sensitive targeting sensor effective under all battlefield
conditions, and one able to see farther than the maximum range of
the TOW missile.
The greater range and sharper picture provided by IBAS improve
the survivability and lethality of the vehicle, boost the probability
of hit for the missile and gun, and reduce the chances of fratricide.
Compared with the first-generation sighting system, the Army calculated
that IBAS with Gen II FLIR increases target detection range by 78
percent at night and 56 percent in daylight.
Once the target is detected, IBAS improves identification capability
by 232 percent at night and 70 percent in daylight. Clear Gen II
FLIR imagery improves recognition of identified targets by 468 percent
at night and 154 percent by day.
The M2A3 makes IBAS imagery available to the vehicle gunner and
commander, and the infantry squad leader on their individual displays.
The squad leader's display enhances the situational awareness of
the foot soldiers before they dismount.
IBAS also generates digital imagery that can be shared with joint
service units and allied forces through the databus, modem and radios
of the Bradley. The 4th Infantry Division is scheduled to become
the Army's first digitized division late this year, and procedures
for transmitting imagery via the single channel ground and airborne
radio system (SINCGARS) and other radios are under development.
On the digital battlefield, forward-positioned M2A3 and M3A3 vehicles
will send real-time Gen II FLIR quality and/or TV imagery with Global
Positioning System location data to supporting ground or air units.
Sharper Eye
Common-module FLIR technology developed in the early 1970s, and
incorporated in the original Bradley sight uses up to 60 individual
infrared detectors to sense thermal contrast. First-generation FLIR
also connects each detector to processing electronics via individual
wires passing through the vacuum dewar assembly, which is a container
used to keep the thermal imager cooled. Image quality is limited
both by the number of detectors and the noise generated by processing
electronics outside the dewar.
By comparison, second-generation FLIR demonstrated in the early
1990s provides more detectors and less noise. The Gen II FLIR in
IBAS contains a 480-by-4 element infrared focal plane array detector
inside the dewar. While the additional detectors enhance the sensitivity
and resolution of the thermal imager, cooled amplifiers boost the
signal-to-noise ratio. Gen II FLIR consequently captures more detail
in distant objects, even those with less thermal contrast. It provides
imagery with television-like clarity that contains more information
for aided target tracking.
IBAS has a 2X and 4X electronic zoom. At the lower magnification,
the Gen II FLIR with its additional detectors provides a 7.5 by
13.3-degree wide field of view, about twice that of first-generation
thermal imagers.
The U.S. Army fielded its first Gen II FLIR based on the SADA II
(standard advanced dewar assembly) technology in TOW ITAS, the improved
target acquisition system used on missile-armed high-mobility multipurpose
wheeled vehicles. While IBAS uses a slightly different GEN II FLIR,
more than 20 percent of IBAS hardware and 35 percent of IBAS software
are common to the earlier ITAS. The improved Bradley acquisition
subsystem integrates more advanced capabilities into the M2A3 and
M3A3 vehicles and shares its B-kit with other platforms.
The TOW missile requires the Bradley gunner to keep the tracking
gate of the sight on the target until impact. IBAS reduces the targeting
timelines and the vulnerability of the launching vehicle with an
aided dual-target tracker that enables the gunner to track simultaneously
two targets in the same field of view. The Bradley gunner uses the
aided tracking function to engage the primary threat while tracking
the next target, and can fire a second missile as soon as the first
TOW round impacts.
The aided target tracker also guides the missile for the first
3.5 seconds of flight, eliminating erratic gunner movements at launch
and decreasing the time needed for the gunner to re-acquire the
target after the "white-out" that accompanies launch.
In addition, IBAS has expansion slots to provide a technological
bridge to next-generation fire-and-forget missiles.
Together, the commander's independent viewer and IBAS give the
modernized Bradley complementary sensors to engage more targets
all around the vehicle. The databus of the new Bradley enables the
vehicle commander to cue the gunner's IBAS image to targets found
by the CIV, and permits the commander to see IBAS imagery and take
control of the weapons system.
Like the early sighting system, IBAS has direct view optics to
give the gunner clear color targeting imagery in daylight. Unlike
the earlier sight, IBAS integrates a charge-coupled device television
camera with daylight (day TV) and near-infrared bands to provide
sharp monochrome imagery under low thermal contrast conditions unfavorable
for FLIRs.
While the TOW missile can be fired only from a stationary vehicle,
the 25mm cannon can be fired on the move. Unlike the early Bradley
sight, IBAS has a two-axis stabilized mirror head that helps fire
accurately on the move. Like the T2SS, IBAS uses the Bradley eye-safe
laser range finder to gauge target distance accurate to within plus
or minus 5 meters. Bradley gunners with accurate range data can
put fire on target without a telltale tracer round to first determine
distance.
Compared with the primitive built-in test capabilities of the TOW
2 sight subsystem, IBAS isolates faults down to the circuit card
or shop replaceable unit to speed troubleshooting and repairs. It
eliminates the regular 180-day verification test required with the
T2SS. The new sighting system also incorporates automatic boresighting
capability to eliminate lengthy boresighting routines and special
equipment. A modular design facilitates repairs and upgrades.
Gen II FLIRs for the modernized Bradley, Abrams and LRAS3 scout
will be supported by a common supply depot and the same specialists
and test equipment. With common B-Kits, about 17 major components
are interchangeable between the sensor systems of the three vehicles.
Joe Hall is IBAS product manager at DRS Optronics, a unit of DRS
Technologies Inc., in Palm Bay, Fla.