| In 1980, the USAF initiated the Pave Pillar
program. The Pave Pillar
program had the goal of developing an advanced avionics architecture
that could be built out of standard modules containing next generation digital
integrated circuits. This approach would allow navigation, communications, sensors,
weapons systems and management subsystems to interact with each other over a local
area network (LAN). This would allow processed information to be presented to the crew
upon request. Instead of managing complex sensors which can overload the pilot with
data, the pilot could concentrate on flying the plane and achieving the mission. Pilot
workload can be dramatically reduced in this fashion. Luckily, the F-22 will be the
first aircraft to benefit from the Pave Pillar program and increase computer processing
power in leaps and bounds. In fact, the F-22's common internal CIP's (Common Internal
processors) will be as much as 100 times faster than the most modern avionics suite
on the F-15 E Strike Eagle.
Amazingly, the F-22 will come equipped with
two Hughes CIP's, with additional space for a third if necessary. Accommodating
the CIP's will be an increased data
bus bandwidth. The DBB will be able to transfer 50MB per second, in comparison to
the meager 1MB max transfer rate on the F-15 Strike Eagle. Unlike previous generations
of fighter aircraft radar, the F-22's APG-77 radar is not a stand alone system.
The radar antenna will be one of many sensor arrays, including the threat warning
system and the electronic warfare equipment. The information from these sensors
will be processed by the CIP's, and relayed to the pilot via fused, flat, color LCD Multi
Function displays. The F-22 will contain no less than six of the color LCD's, with
only 3 backup analog displays for emergencies. The color MFD's will give the pilot a
"God's eye" view of the battle situation unlike any modern fighter jet.
Mentioned in the above paragraph, the APG-77 radar
is unlike any other fighter radar in the skies. It cannot be rivaled.
The radar antenna is a elliptical, fixed active array which contains 1,500
transmit & receive (TR) modules. A individual TR module is essentially a mini radar in
its own right. In comparison to an object, each TR module
is about the size of an adult finger. A remarkable feature of the APG-77 radar is that
it contains no mechanical linkages. Anotherwards, the actual antenna does not move.
This does not have any effect on the performance be warned! It is able to sweep 120
degrees of airspace maximum, at 6 bar levels (change in altitude) instantaneously! In
comparison to the F-15 Strike Eagle's APG-70 radar, it takes 14 seconds to scan that amount
of airspace. The APG-77 is capable of performing this feat by forming multiple radar beams
to rapidly search the airspace.
The Low Probability of Intercept (LPI) capability is
without a doubt the most impressive feature of the APG-77 radar. With conventional
RWR/ESM systems, it is extremely difficult to detect LPI pulses. This translates
into a advantage for the F-22. The F-22 will be capable of performing an active
radar search on equipped RWR/ESM equipped fighter aircraft without the target knowing he
is being illuminated. The APG-77 does not emit high energy pulses in a narrow frequency band
like conventional radars. Instead, it emits low energy pulses over a wide frequency band.
This is called spread spectrum transmission. The way it works is, when multiple echoes
are sent back to the radar, the radar's signal processor converts the signals together
instead of individual pulses. The amount of energy reflected back to the target is about the
same as a HPI radar, but because each LPI pulse has considerably less amount of energy
and does not necessarily fit the normal frequency pattern, the target will have a difficult
time detecting the F-22. This becomes more evident in a BVR engagement. In fact, the F-22
can launch an AMRAAM missile without even establishing a lock-on. The unfortunate target
won't even receive a missile inbound warning until the missile has activated its own radar
and is on final intercept. By this period, it is almost impossible to evade the missile. The
pilot will have no other choice but to eject.
The F-22 and its APG-77 radar will also be able to employ better Non-Cooperative
Target Recognition (NCTR). This is accomplished by forming incredibly fine beams and
by generating a high resolution image of the target by using Inverse Synthetic Aperture
radar (ISAR) processing. ISAR uses Doppler shifts caused by rotational changes in the targets
position to create a 3D map of the target. The target provides the Doppler
shift and not
the aircraft illuminating the target. SAR is when the aircraft provides the Doppler shift. Thus,
the pilot can compare the target with an actual picture radar image stored in the F-22's data base.
This ingenuitive process is possible courtesy of the F22's CIP's.
And just when you thought it couldn't get any better, listen up. The
F-22 will have the first integrated avionics suite ever flown on a combat aircraft. The
Northrop/Grumman-Texas Instruments APG-77 radar, Lockheed Martin electronic warfare suite and
the TRW communications/navigation/IFF subsystems are all included. Over one million lines
of computer code will comprise the system. The electronics will be liquid cooled, an much
lighter than the old electronics found in fighter a/c such as the F-14, F-15 & F-16. The F-22's
CIP's will process 700 million operations per second, which is roughly equivalent to four
Cray supercomputers. An integrated countermeasures set will be controlled by the CIP's. Rapid
systems programming and upgradeability are available in the time of a crisis. The onboard jammer,
communication, navigation, & IFF antennas, in addition to the RWR is contained on smart skins
on the wings.
Included in the Communications/Navigation/Identification system is an Inter/Intra-Flight Data Link (IFDL) that allows all F-22s in a flight to share target and system data
automatically and without radio calls. One of the original objectives for the
F-22 was to increase the percentage of fighter pilots who make
'kills'.With the IFDL, each pilot is free to operate more autonomously because, for example,
the leader can tell at a glance what his wing man's fuel state is, his weapons
remaining, and even the enemy aircraft has targeted. Classical tactics based on
visual 'tally' (visual identification) and violent formation maneuvers that
reduce the wing man to 'hanging on' may have to be rethought in light of such capabilities. This
link also allows additional F-22 flights to be added to the
net for multi-flight coordinated attack. |
