The AN/APG-76 radar is a pulse Doppler Ku band multi-mode radar developed and manufactured by Northrop Grumman. AN/APQ-92 The first radar of the radar family AN/APG-76 belongs to is AN/APQ-92, which equipped A-6A. AN/APQ-92 is a search and navigational radar, with function called search radar terrain clearance (SRTC) to generate a synthetic terrain display on the pilot's Vertical Display Indicator (VDI), which is a large cathode ray tube (CRT) display in the center of the pilot's console, right under the gun sight. The display showed vertical terrain development in a 53 degree x 26 degree window about the projected flight path. If the Intruder was heading for a valley between two hills, the pilot would see return generally in the shape of two hills (one on either side of the display), with a curving "V" notch in the center between them. The limitation of SRTC is in its inability to detect smaller artificial features - like cables suspend across a valley. AN/APQ-92 is part of DIANE (Digital Integrated Attack/Navigation Devices), which consists of multiple radars: the Norden AN/APQ-92 search and navigation radar, the separate AN/APQ-88 for tracking/attacking, AN/APN-141 radar altimeter, & AN/APN-122 navigational radar to provide position updates to the AN/ASN-31 inertial navigation system. AN/APQ-103 AN/APQ-103 is the successor of AN/APQ-92, and it is used in conjunction with AN/APN-153 Doppler navigational radar that replaced earlier AN/APN-122, and AN/APQ-112 radar replaced AN/APQ-88. The APQ-103/APN-153/APQ-112 upgrade is part of the improvement of DIANE installed on A-6B. AN/APQ-112 AN/APQ-112 is a tracking radar that replaced earlier AN/APQ-88 radar developed by Naval Avionics. While the AN/APQ-88 could only track moving targets, the APQ-112 could track stationary targets as well, and it had slightly better resolution and greater reliability than AN/APQ-88. AN/APQ-112 not only could perform all functions of AN/APQ-88, but was also capable of performing some functions of AN/APQ-103. As more advanced version of AN/APQ-112 was developed, it replaced AN/APQ-103. However, the attempt to replace two separate radars failed at the time due to increased mission requirement, and a separate dedicated fire control radar was needed. As a result, the vastly improved Sperry Corporation AN/APQ-127 was adopted, while AN/APN-186 navigational radar replacing earlier AN/APN-153 in earlier A-6B. APN-186/APQ-112/APQ-127 suit is designed as part of A-6C specially dedicated for night attack missions against the Ho Chi Minh Trail in Vietnam. AN/APQ-129 AN/APQ-129 is a derivative of AN/APQ-112 for EA-6A, allowing EA-6A to fire AGM-45 Shrike