Читать книгу Introduction to UAV Systems - Mohammad H. Sadraey - Страница 43

The Global Hawk has a wide‐band satellite data link and a line‐of‐sight data link. Data is transferred by: (1) Ku‐band satellite communications, (2) X‐band line‐of‐sight links, and (3) both Satcom and line‐of‐sight links at the UHF‐band. The synthetic aperture radar and ground moving target indicator operates at the X‐band with a 600 MHz bandwidth.

The air traffic control (ATC) and command‐and‐control (C2) of the NASA Global Hawk from the Dryden Flight Research Center is applied in two distinct regions: (1) The line‐of‐sight (LOS) and (2) The beyond line‐of‐sight (BLOS). The communications link used for LOS are through UHF/VHF links. The primary communications links used for BLOS are two Iridium Satcom links. However, an Inmarsat Satcom link provides a backup communications capability.

The NASA Global Hawk payload communications architecture is independent of the communications links utilized to control the aircraft. Four dedicated Iridium SatCom communication links are used for continuous narrow band communications between the ground station and the UAV payloads. Moreover, two additional Iridium links are used to monitor power consumption by individual payloads, and to control features such as lasers and dropsonde. The use of the Iridium system provides a complete global coverage, including the Polar regions.