Demonstration of a high-altitude laser crosslink

The requirement to send ever increasing amounts of tactical military information between sensor aircraft and information processing facilities for command and control purposes has begun to reach the physical limits of present RF data links, even when data compression is employed. Use of laser data links is under consideration by the United States Air Force and development of an airborne laser data link is under way by the United States Air Force Research Laboratory Sensors Directorate (AFRL/SN). This technology development program is being conducted in two phases. The first phase included the design and evaluation of a laser data link ground demonstration. This demonstration was carried out in August and September, 1995 between a laser terminal on Mount (Mt.) Mauna Loa on the island of Hawaii and a similar laser terminal on Mt. Haleakala on the island of Maul located 150 kilometers (km) away. The terminals used in this ground demonstration were capable of 1.1 gigabits per second (GBPS), full duplex communication with bit error rates (BERs) of 10^-6 or better. A motion and vibration base was used to simulate flight conditions, while the terminal instrumentation was used to collect atmospheric effects data. Results of the ground demonstration, including signal acquisition, tracking stability, and scintillation were used to modify the design of the laser terminal for follow-on air-to-air operations. The second phase of the AFRL/SN development program under way is the transition of the ground demonstration results into a refined terminal design for installation into two business class jet aircraft. Flight demonstration of the laser data link between these kinematic aerial platforms will be performed between two T-39A (Sabreliner 40) test aircraft at distances up to 500 km and altitudes up to 40 kft (12.2km). A ground-based field test of these two refined laser terminals is planned for November 1999 between Mt. Palomar in San Diego, CA and a test site 50 km away. The installation of high-bandwidth laser data link terminals for communication between high-altitude aerial platforms provides for two advances. First, the ability to use advanced airborne sensors generating very large amounts of raw data in near real-time. Second, command and control, decisions can be made based on a more timely and comprehensive database of information