Fade Analysis of ORCA Data Beam at NTTR and Pax River

摘要

The DARPA Optical RF Communications Adjunct (ORCA) program was designed to bring high data rate networking to the warfighter via airborne platforms. Preliminary testing of the ORCA free-space optical communication (FSOC) laser beam was performed on May 12, 2009 by the Northrop Grumman Corporation (NGC) at Patuxent (PAX) River Naval Air Base in Maryland. Phase I testing of the ORCA system from/to an aircraft to/from a mountaintop was then conducted by NGC at the Nevada Test and Training Range (NTTR) located on the Nellis Air Force Range near Tonopah, NV. The University of Central Florida (UCF) was separately contracted by DARPA to measure path-averaged values of the refractive-index structure parameter C(2/n), the inner scl(o), and the outer scale of turbulence L0 along the propagation path from the NGC BAC 1-11 aircraft to Antelope Peak during the ORCA testing at NTTR. The testing took place over May 16-18, 2009 and a Report on those measurements was submitted to DARPA in September 2009. Additional tasks assigned to UCF after the NTTR testing included further analysis of the aero-optic effects from the aircraft boundary layer, adaptive-optics (AO) compensation issues, and fade statistics at both PAX River and NTTR. Later, the UCF team was also tasked to analyze the Integrated RF/Optical Networked Tactical Targeting Networking Technologies (IRON-T2) data taken over a 147-km link between two mountains in Hawaii on October 16, 2008. The UCF team took direct measurements of only the beacon beam at NTTR and made no measurements at PAX River or Hawaii. The beacon beam data collected by UCF was used to calculate path-averaged atmospheric parameters and to investigate aero-optic effects. In addition, UCF was provided with some of the power in the fiber (PIF) data taken by NGC on the ORCA data beam at NTTR and at PAX River in order to address the fading statistics associated with the data beam and the benefit of the AO compensation system.