New gPs signals aviation grade Chips Off the Block IIF

j u l y / a u g u s t 2 0 1 0 www.insidegnss.com While the GNSS community at large looks forward to the addition of any new generation of navigation satellites, the first Block IIF satellite — launched in May 2010 and designated space vehicle number (SVN) 62 — marks an especially important step forward for the aviation community. Non-aviation applications may take advantage of GNSS receivers that use any and all available ranging sources. However aviation requires signals operating in designated safety-oflife aeronautical radionavigation service (ARNS) bands to avoid interference from overlapping signals. GPS L1 operates in a designated ARNS band, but L2 does not. The new L5 signal — the first operational version of which has begun transmitting on a test basis recently — is also in an ARNS band. And, as with L1, L5 can be used for aviation. Because aviation users must meet rigorous safety-related standards, they need to rely only on signals that meet strict criteria for performance and reliability. This often translates into demands for ensuring robust performance and high availability of service while having fewer ranging sources upon which it can rely. One area of concern is imperfection in the shapes of the broadcast chips that may lead to differential range errors across different receiver types. This article focuses on an evaluation of the new signals’ chip shapes and their potential effect for aviation users. Satellite-based navigation signals used for aviation must originate from well-established and trustworthy sources, such as GPS. Although other satellite navigation systems exist or are under development, none has gained the pedigree that GPS has earned from years of continued operation and dependable performance. New GNSS signals — including GPS L5 — planned for use in aviation New gPs signals aviation grade Chips Off the Block IIF