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The IUP Journal of Electrical and Electronics Engineering:
An Analysis of GPS Code Minus Carrier Measurements for GBAS Applications
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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.

 
 

The NAVigation Satellite Timing And Ranging Global Positioning System (NAVSTAR GPS) is an all-weather satellite-based navigation system that facilitates the users equipped with suitable receivers to compute their 3D position and time. GPS was developed by the US Department of Defense (DOD) primarily for military purpose and therefore the access to civil users was limited. It is only when Selective Availability (SA) was eliminated on May 2, 2000, the civilian applications of GPS became more pronounced (Hoffmann

et al., 1994). Today, GPS is used for providing positioning and timing solutions for a large variety of applications in various fields. To determine user position, the GPS receivers acquire the signals from GPS satellites and measure ranges to all the satellites. But the range is corrupted by various error sources including atmospheric errors, satellite-based errors and receiver errors (Misra and Enge, 2001). GPS provides two types of range measurements called the code measurements and carrier measurements. In this paper, the models for the two types of range measurements are presented and an analysis of Code Minus Carrier (CMC) measurement is carried out for Ground-Based Augmentation System (GBAS) applications.

 
 
 

Electrical and Electronics Engineering Journal, Global Positioning System (GPS), Ground-Based Augmentation System (GBAS), Code Minus Carrier (CMC), Ionospheric delay