With production beginning in 1984, the AN/APQ-164 radar is a phased array navigation and fire control radar developed by Northrop Grumman for the US Air Force to be used onboard the B-1B aircraft. The AN/APQ-164 system is composed of a two axis electrically scanned phased array antenna, a radar receiver transmitter, a programmable signal processor, dual mode transmitter and a video signal processor. Originally called AN/APG-164, this radar provides the B-1B with a Monopulse Ground Map (MGM) for an all weather area navigation aid. It also provides a precise all-weather automatic Terrain Following (TF) and Terrain Avoidance (TA) capability for the B-1B.
The AN/APQ-164 also functions as a high resolution Synthetic Aperture Radar (SAR) for navigation and targeting nuclear and strategic weapons in all weather conditions. The radar can be modified with a Multitarget Track (MTT) software mode for Advanced Medium Range Air-to-Air Missile (AMRAAM) deployment. This radar system was the first ever, passive element phased array with a beam steering controller and a real time processor that allowed simultaneous Scanning Aperture Radar (SAR) and Terrain Following (TF) imagery. The APQ-164 was first flown on a B-52 in 1977. The HELRATS system was used to simultaneously track two missiles and then feed the signal via fiber-optic cable to a system that used the data for targeting.
With more than 120 units delivered, the AN/APQ-164 is highly regarded by B-1B combat crews for effectiveness and reliability. In April 2006 the Boeing Company received a $180 million contract to upgrade the APQ-164 radar system on the US Air Force fleet of 67 B-1B long-range bomber aircraft. This upgrade focused on replacement of the radar's transmitter/receiver and the processor under the Reliability and Maintainability Improvement Program (RMIP). The APQ-164 radar upgrade is expected to begin in 2011 and complete by 2014 with Northrop Grumman supplying the RMIP kits and a new software package.