Performance Analysis of L2 and L5 CNAV Broadcast Ephemeris for Orbit Calculation

摘要

GPS ephemeris error is a limiting factor in GPS position solution precision. The newly introduced GPS Civil Navigation (CNAV) broadcast message, an upgraded version of the legacy NAV message on the GPS L1 signal, is designed to provide users with more precise satellite orbit and timing parameters in GPS ephemeris. A CNAV message broadcast test was conducted from June 15th to 29th, 2013 on the L2C and L5 bands. Baseband civil GPS signals on L1, L2, and L5 were recorded during the test using wideband software radio front ends. The signals were acquired and tracked, and the navigation messages were decoded by the conventional Viterbi method and a more computationally efficient matrix-based method. GPS ephemerides were extracted from the CNAV messages to compute satellite orbit solutions. In this paper, the orbit solution accuracy is compared with that computed from Legacy NAV messages during the same time period to demonstrate the improvements in the CNAV ephemeris precision.