The AN/APG-77 is a multifunction low probability of intercept radar installed on the F-22 Raptor fighter aircraft. The radar was designed and initially built by Westinghouse and Texas Instruments, and production continued with their respective successors Northrop Grumman and Raytheon after acquisition. It is a solid-state, active electronically scanned array (AESA) radar. Composed of 1,956 transmit/receive modules (TRM), each about the size of a gum stick, it can perform a near-instantaneous beam steering (in the order of tens of nanoseconds). The APG-77 was highly appreciated by pilots transitioning from F-15s upon the F-22's introduction in 2005, providing a massive boost in situational awareness. The APG-77 has an incredibly fast scan time across its 120 degree field of view and could detect aircraft from over 320 mi (515 km) away. The AN/APG-77 system itself exhibits a very low radar cross-section, supporting the F-22's stealthy design. The upgraded APG-77(V)1 may have an even greater range. Much of the technology developed for the APG-77 was used in the AN/APG-81 radar for the F-35 Lightning II, and in turn the technology from the APG-81 was applied to the upgraded APG-77(V)1. The APG-77(V)1 was installed on F-22 Raptors from Lot 5 and on. This provided improved air-to-air performance, full air-to-ground functionality (high-resolution synthetic aperture radar mapping, ground moving target indication and track (GMTI/GMTT), automatic cueing and recognition, combat identification, and many other advanced features).