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

Hang Yin, Yu T. Morton, Mark Carroll, Eric Vinande

Peer Reviewed

Abstract: Ephemeris error is a limiting factor in GPS position accuracy. The newly introduced GPS Civil Navigation (CNAV) broadcast message, an upgraded version of the legacy NAV message, is designed to provide users with more precise satellite orbit and timing parameters. A CNAV broadcast test was conducted in 2013 on the L2C and L5 bands. Since April 2014, pre-operational CNAV started to broadcast to civilian users. Baseband civil GPS signals on L1, L2, and L5 were recorded during the broadcast test and the pre-operational broadcast using wideband software radio front ends. The signals were acquired and tracked, with navigation messages decoded by the conventional Viterbi method and a computationally efficient matrix-based method. GPS ephemerides were extracted from the messages to compute satellite orbit solutions. This paper evaluates the orbit solution of both CNAV and Legacy NAV during the same time period to demonstrate the improvements in the CNAV ephemeris accuracy.
Published in: NAVIGATION: Journal of the Institute of Navigation, Volume 62, Number 2
Pages: 121 - 130
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