An Analysis of GPS Code Minus Carrier Measurements for GBAS Applications

Abstract

GPS provides its users with the advantage of two types of range measurements called code measurements and carrier-phase measurements. The difference between both these measurements is called the GPS Code Minus Carrier (CMC) measurement. In this paper, an analysis of the model of GPS CMC measurement is carried out for Ground-Based Augmentation System (GBAS) applications. The analysis has been carried out for several satellites and the results due to three satellites are presented. It is concluded that CMC measurement consists of two times the ionospheric delay (2I) and multipath plus receiver noise component. As the dual frequency receivers provide precise estimate of ionospheric delay component (I), an estimate of multipath plus receiver noise component can be easily obtained from CMC. This technique finds its application in multipath mitigation techniques in GBAS systems all over the world.

Keywords: Global Positioning System (GPS), Ground-Based Augmentation System (GBAS), Code Minus Carrier (CMC), Ionospheric delay