The primary target detection sensor of the F-16A/B is the Westinghouse AN/APG-66 pulsed-Doppler radar. Pulse-Dopper radars operate by measuring the frequency shift that is created by target velocity in order to discriminate between a genuine aircraft and ground clutter. The APG-66 has a medium pulse repetition frequency or PRF for short (typically 10 to 15 kHz). It operates in the I/J band and has a flat-plate planar array antenna. Sixteen operating frequencies are available within the I/J band, and the pilot can select between any four of them.
The APG-66 reduces the radar data to digital form and presents the pilot with a synthetically-generated image made up of a set of predefined symbols. The display is free from clutter and is much easier to read than previous displays, but the ability to discriminate between real and false targets depends entirely on the quality of the software used to control the signal processing equipment.
Radar operating modes may be selected by the pilot by using either the throttle, the sidestick controller, or knobs on the radar control panel. The primary air-to-air search mode is Downlook, which provides clutter-free indication of low- flying targets. Fighter-sized aircraft can be detected at ranges of up to 35 miles. In the Uplook mode, there is no need for the filtering out of spurious responses from the ground, and the pilot can detect targets at ranges of up to 50 miles.
Four modes are available for air-to-air combat. In the Dogfight mode, the radar automatically scans a 20-degree by 20-degree field in the forward direction. If the pilot can see the the target in his HUD, and the range is less than ten miles, the radar will automatically lock on. If high-g maneuvers are to be carried out, the area to be searched can be altered to a 40-degree by 10-degree pattern. If multiple targets are present, the pilot can press the Designate button on his sidestick controller. The radar will then operate in a slim narrow-beam mode, and by maneuvering his aircraft, the pilot can place the beam onto the required target. When he releases the designate button, the radar will acquire and track the chosen target. A Slewable air-combat mode can be used to allow the scan pattern to be moved in anticipation of target maneuvers.
Seven different modes are available for air-to-surface attacks. The first of these is Air-to-Ground Ranging, which is automatically selected during continuously-computed impact point (CCIP) and dive-toss attacks. CCIP attacks use a ground mapping mode, which gives a plan position indicator display at 10, 20, 40, or 80 nm range, and scan widths of plus or minus 10, 30 , or 60 degrees. There are dedicated sea-surface search modes, which are designed to eliminate the clutter caused by spurious reflections from ocean waves. There is a Beacon mode which can be used in conjunction with ground-located radar beacons to take navigational fixes or to carry out offset weapons delivery. In the air-to-air role, this mode is used by the radar to locate flight refuelling tankers by interrogating their beacons. There is a Freeze mode in which the radar carries out a quick scan, and the image is held on the display while the radar transmitter is shut off. A moving symbol on the display continues to simulate aircraft motion. There is a special Doppler beam sharpened mode which is capable of achieving a higher definition of ground features. This mode relies on the processing of Doppler shift information, and is available only at angles between 15 degrees and 60 degrees off the aircraft's velocity vector. If the aircraft should happen to bring the area being viewed to within 15 degrees of the aircraft's centerline, the radar will automatically switch to the normal ground mapping mode.
Integration of the F-16 avionics makes extensive use of the MIL-STD-1553 databus.
In 1980, Westinghouse was awarded a contract to develop a programmable signal processor and a dual mode transmitter for the APG-66. The dual-mode transmitter would use low PRFs for air-to-ground work, and medium to high PRFs for air-to-air combat. These modifications were intended to match the performance to the AMRAAM missile and to improve the air-to-ground capability.
F-16C and D Block 25 aircraft introduced the improved Hughes APG-68 radar with new dual-mode traveling wave tube technology to provide low, medium, and high PRFs. A Programmable Signal Processor (PSP) is fitted which is based on VHSIC technology. The APG-68 has a longer range and can handle radar-guided missiles at BVR, including the AIM-120A AMRAAM "fire-and-forget" missile. The improved data processing capability of the APG-68 enables the set to operate in a track-while-scan mode, which makes it possible to follow multiple targets at the same time and rank them in order of priority. Higher-resolution mapping modes are also available. A raid cluster resolution mode is available with the APG-68 which allows the pilot to distinguish between the individual aircraft flying in a tight formation at long range. The set also has an ACM (air combat maneuvering) mode which allows the radar to follow hard-maneuvering targets at short ranges.
Data from the radar and navigation systems are displayed to the pilot on either a heads-up or heads-down displays. The HUD is built by Marconi Avionics (now known as GEC Avionics). Marconi was a pioneer in the development of HUD technology, and built the first HUD to enter service on a production aircraft, applied to the Hawker Siddeley Buccaneer in 1960. If the canopy happens to be shattered by the impact of a particularly large bird, the HUD is robust enough to act as a temporary windshield to protect the pilot. The field of view of the HUD of the F-16A/B is 15.5 degrees in azimuth and 9 degrees in elevation. In the LANTIRN-equipped later models of the F-16C or D, the field of view of the HUD is 30 by 20 degrees.
The basic communications installations in the F-16A and B consists of Collins ARC-186 VHF AM/FM and Magnavox ARC-164 UHF tranceivers, a Magnavox KY-58 secure voice system, and an interference blanker by Novatronics.
Between 1984 and 1986, the USAF F-16 force was equipped with the JTIDS jam-resistant command, control, and communication system.
The basic radar warning system (RWR) carried by the F-16 is the Itek ALR-69. It was based on the earlier ALR-46. It has five general purpose surveillance receivers plus a sixth frequency-selective receiver. The USAF has been reluctant to export the ALR-69 to foreign air forces. The ALR-74 is scheduled to replace the ALR-69. The F-16C/D Block 50/52 carries the Loral ALR-56M radar warning receiver.
The F-16 can carry the ALQ-119 or the more modern Westinghouse ALQ-131 electronic countermeasures pod on the fuselage centerline point. The Westinghouse ALQ-131 is a 573-pound modular pod-mounted system capable of coping with a wide range of threats. By selecting individual modules for inclusion in the pod, the user can configure the pod to handle threats spread over one to five frequency bands. Modules are available to cope with all frequencies used by current anti-aircraft missile systems, and both noise and deception-jamming modes are available. The pod has its own digital computer which can be reprogrammed on the flightline before takeoff to match the threat to be encountered on the mission.
Block 50/52 F-16s initially used the more reliable Northrop Grumman APG-68(V)5 radar, with a 30 percent greater air-to-air detection range and a synthetic aperture radar mode for high-resolution mapping and target detection and recognition. In August of 2004 Northrop Grumman were contracted to upgrade the APG-68 radars of Block 40/42/50/52 aircraft to the (V)10 standard, which provided all-weather autonomous detection and targeting for GPS-aided precision weapons, SAR mapping and terrain- following radar modes, as well as interweaving of all modes.
The F-16E/F is outfitted with Northrop Grumman's AN-APG-80 active electronically scanned array (AESA) radar. Northrop Grumman developed the latest AESA radar upgrade for the F-16 (selected for USAF and Taiwan Air Force F-16 upgrades), In July 2007, Raytheon announced that it was developing a Next Generation Radar (RANGR) based on its earlier AN/APG-79 AESA radar as a competitor to Northrop Grumman's AN/APG-68 and AN/APG-80 for the F-16.[