from in the air. The Global Hawk is capable of operating autonomously and "untethered". A military satellite system (X Band Satellite Communication) is used for sending data from the aircraft to the MCE. The common data link can also be used for direct down link of imagery when the UAV is within line-of-sight of compatible ground stations. For dense flight areas the autonomous navigation is switched off and the RQ-4 is remote controlled via the satellite link by pilots on the ground who are supplied with the same instrument data and who carry the same responsibilities as pilots in crewed planes. The ground segment consists of a Mission Control Element (MCE) and Launch and Recovery Element (LRE), provided by Raytheon. The MCE is used for mission planning, command and control, and image processing and dissemination; an LRE for controlling launch and recovery; and associated ground support equipment. The LRE provides precision Differential GPS corrections for navigational accuracy during takeoff and landings, while precision coded GPS supplemented with an inertial navigation system is used during mission execution. By having separable elements in the ground segment, the MCE and the LRE can operate in geographically separate locations, and the MCE can be deployed with the supported command's primary exploitation site. Both ground segments are contained in military shelters with external antennas for line-of-sight and satellite communications with the air vehicles. Sensor packages Radar The Global Hawk carries the Hughes Integrated Surveillance & Reconnaissance (HISAR) sensor system. HISAR is a lower-cost derivative of the ASARS-2 package that Hughes developed for the U-2. It is also fitted to the US Army's de Havilland Canada RC-7B Airborne Reconnaissance Low Multifunction (ARLM) crewed aircraft, and is being sold on the international market. HISAR integrates a SAR-MTI system, along with an optical and a thermography imager. All three sensors are controlled and their outputs filtered by a common processor and transmitted in real time at up to 50 Mbit/s to a ground station. The SAR-MTI system operates in the X band in various operational modes; such as the wide-area MTI mode with a radius of , combined SAR-MTI strip mode provides resolution over wide sections, and a SAR spot mode providing resolution over . In July 2006, the USAF began testing the Global Hawk Block 30 upgrades in the Benefield Anechoic Facility at Edwards AFB. Upgrades include the Advanced Signals Intelligence Payload, an extremely sensitive SIGINT processor.