TABLE OF CONTENTS GPS signal carries with it data from the satellite that the user receiver needs to solve for position, velocity, and time. This chapter describes these GPS navigation data in some detail and gives the background analysis useful in understanding their functions. The data formats correspond to the ICD-GPS-200. [1] The first section gives a complete overview of the entire navigation data format and overall frame structure. The second section describes in some detail the format and algorithms of ICD-GPS-200 for each of the subframes. The final sections present some of the physical and mathematical bases for the algorithms of Sec. II. Detailed discussion of the effects of relativity, the ionosphere, and troposphere is reserved for later chapters. A table of physical constants used in this chapter and elsewhere is given in the Appendix.
The 50 bits/s datastream provides the user with several key sets of data required to obtain a satisfactory navigation, geodetic survey, or time transfer solution. These navigation data are uploaded to each satellite by the GPS Control Segment (CS) for later broadcast to the user. Uploads occur once per day, or more often, if needed to keep the user range error (URE) within specification. The navigation data provide the information shown in Table 1. The form of the information is also described in the table.
