AN/APG-73
The AN/APG-73 is the successor multi-mode, digital radar to the AN/APG-65 that flies in U.S. Navy's F/A-18 Hornet strike fighter. It can be used with the Sparrow and Sidewinder missiles and the 20-mm gun for air-to-air combat, and a variety of conventional and guided weapons for ground attack.
The system consists of five line-replaceable units (LRU). Faults are identified by the radar's built-in test (BIT), which also runs pre-flight and in-flight diagnostics. Specified mean time between failures (MBTF) is more than the AN/APG-65 's 106 hours.
In the upgrade, only the antenna and the transmitter remain unchanged in the first phase. The elliptical, flat-plate, planar array antenna has low sidelobes for better electronic countermeasures (ECM) resistance. It is electrically driven.
The gridded travelling wave tube (TWT) transmitter is located behind the antenna and under the other LRU. It is liquid-cooled, which Hughes claims reduces stress on the components and increases reliability and software programmable.
The heart of the APG-73 update is the new receiver/exciter and developing new components that replace the general-purpose radar data processor (RDP) and digital programmable signal processor (PSP). Better resolution, added modes and better ECCM are some of the benefits. For example, the broader rec eiver bandwidth allows the radar to evade ECM and tune in on Marine Corps targeting beacons. Still higher pulse compression improves resolution. The power supply's efficiency rating rises from 72 percent to 85 percent.
Processing speed and power increases are considerable. The PSP's speed jumps from 7.1 million complex operations per second (MCOPS) to 60 million. Spare capacity allows a later increase to 80 million. Use of Fast Fourier Transforms (FFT ) is now general rather than selective.
Programming is written in Jovial, which allows Hughes to borrow coding from the APG-70 and APG-71 systems. Memory capacity expands to one megaword in the PSP and two megawords in the RDP. RDP speed increases to two million instructions per second. The RDP also is more compact and more rugged.
In the radar receiver, an 11-bit analog-to-digital converter using silicon bipolar transistors as in the APG-65, but with improvements. It receives an almost four-fold processing speed increase, which sharpens resolution in air-to-air combat modes. The six-bit, air-to-ground A/D converter runs at 58 MHz -- more than seven times faster than that of the APG-65. Along with faster processing, the increased bandwith makes it possible for the APG-73 to interact with U.S. Marine Corps targeting beacons.
A later phase upgrades synthetic aperture radar (SAR) mode processing and a motion sensor subsystem in the radar itself that counteracts distortions from airframe bending that degrade accuracy in the current inertial reference unit. A third phase would introduce the active array antenna.
The APG-73 has a large variety of air-to-air and air-to- surface modes, including all of those found in the APG-65. Air-to-air modes include range-while-search, track-while-scan (TWS ), velocity search, single-target tracking, raid assessment, three Air-Combat Maneuvering (ACM) and the gun-director mode.
Air-to-ground modes include Doppler beam sharpening, real beam ground mapping, terrain avoidance, sea-surface search, air-to-surface ranging, fixed- or moving-target tracking, precision velocity update and SAR processing.
WEIGHT: 450 lb
DIMENSIONS: Volume <14.8 cu ft (0.42 cu m)
PERFORMANCE:
Source: usni.org