Proposed New L5 Civil GPS Codes

Abstract

: Future generations of GPS space vehicles (SVs) will have three civil signals instead of the present single civil signal at the L1 frequency of 1575.42 MHz. These future-generation GPS SVs will have a second civil signal centered at the L2 frequency of 1227.6 MHz. The largest improvement in civil user performance, however, will be obtained via the third civil signal at the L5 frequency of 1176.45 MHz. This L5 signal is a new higher-performance civil signal having both a data-free component and a quadrature data modulated component. Both components are modulated with separate pseudorandom noise (PN) codes having a PN-chip clock rate of 10.23 Mcps and a period of 10230 chips or 1 ms. This paper describes the proposed new civil codes for the data-free and data channels and their multiple access properties, and presents block diagrams of possible SV modulators and user receivers.