Following directly from http://www.f-22raptor.com/
The F-22's avionics and software system is the most
advanced ever integrated into an aircraft. It is the first
aircraft to use integrated avionics, where the weapons
management system, electronic warfare system and the
AN/APG-77 radar work as one, giving the pilot
unprecedented situation awareness.
A joint venture of Northrop Grumman's Electronic Sensors
and Systems Division (ESSD) and Raytheon-Texas Instruments
Inc. is developing the advanced AN/APG-77 radar for F-22.
The AN/APG-77 radar is designed for air-superiority
and strike operations and features a low observable,
active aperture, electronically-scanned array with
multi-target, all-weather capability.
The radar is key to the F-22's integrated avionics and
sensor capabilities. It will provide pilots with detailed
information about multiple threats before the adversary's
radar ever detects the F-22. This is also called BVR, or
Beyond Visual Range capability.
It will give an F-22 pilot the possibility in
air-to-air combat, to track, target and shoot at multiple
threat aircraft before the adversary's radar ever detects
The F-22's Northrop Grumman/Texas Instruments-built
AN/APG-77 radar is an active-element, electronically
scanned (that is, it does not move) array of over 1000
finger-sized transmitter / receiver modules. Each module
weights ca 15g and has a power output of over 4W. The
APG-77 is capable of changing the direction, power and
shape of the radar beam very rapidly, so it can acquire
target data, and in the meantime minimizing the chance
that the radar signal is detected or tracked.
Most of the mechanical parts common to other
radar have been eliminated, thus making the radar
more reliable. This type of antenna, which is
integrated both physically and electro magnetically
with the airframe, provides the frequency agility,
low radar cross-section, and wide bandwidth
necessary to support the F-22's air dominance
One requirement that drove all of the ATF designs
was a wide field of regard for sensors, enabling the
Raptor to acquire and track multiple targets beyond visual
range. The requirement called for a 120-degree radar field
of regard on each side of the nose.
A forward-looking infrared search and track
capability was also desired. Lockheed approached the
field-of-regard requirement for the radar with three radar
arrays placed in the nose of the aircraft (one facing
forward and two facing sideways). Each wing root carried
an infrared search and track system that operated through
The avionics software is to be integrated in three
blocks, each building on the capability of the previous
block. Block 1 is primarily radar capability, but Block 1
does contain more than 50 percent of the avionics suite's
full functionality source lines of code (SLOC) and
provides end-to-end capability for the sensor-to-pilot
This Block 1 software enables the basic operation of the
radar and its initial mode complement, including the
simultaneous operation of search and track modes and
systems health and maintenance or built-in-test modes.
At the Boeing Avionics Integration Laboratory the F-22
radar was integrated with the avionics mission software
and other aircraft avionics sensors such as the electronic
warfare system, and the communications, navigation and
By the first quarter of 1998, the radar was
delivered to The Boeing Company's F-22 Avionics
Integration Laboratory in Seattle, Wash., where engineers
integrated the radar with other F-22 avionics.
Meanwhile, flight testing of a second F-22 radar continued
aboard a modified Boeing 757 testbed aircraft at ESSD. The
test bed consisted of an F-22 forward fuselage installed
on the 757's forward pressure bulkhead. Electronic warfare
(EW) and communication, navigation and identification
(CNI) sensors were mounted directly on the sensor wing,
which was designed to simulate the sensor positioning
found on the F-22's wings.
The cabin had space for 30 software engineers
and technicians who could evaluate avionics and
identify anomalies, in real time. A simulated F-22
cockpit was installed in the cabin of the Flying
Test Bed. It had all primary and secondary F-22
displays, as well as the throttle and stick.
The conducted flight tests successfully demonstrated
the expected levels of performance of the F-22 radar,
including basic search and track functions.
Full-scale production of the F-22 radar is scheduled to
begin in 1999.
Data courtesy of Lockheed, Boeing, testbed image Mike
Casad, Raytheon Systems, Texas Instruments, USAF
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